Merge pull request 'The mesh makes the bus's certificate itself' (#145 ) from fix/the-mesh-makes-its-own-bus-certificate into main

The mesh makes the bus's certificate itself
novox/hq 04-ISSUES/146. The foundation made it by running openssl inside the broker's image, which worked while the broker was one that carried it and stopped the day the bus changed: the new one has a shell and no openssl, so the step exited 127 and no mesh could be raised. No other image the bundle names has it either, so there was nothing to substitute. broker certificate --into <dir> writes the pair, --check is the step's verify. Self-signed on purpose — a host pins this server's exact certificate (ADR 0004) and at genesis there is no authority to ask — and made once, because a second certificate is one every host that pinned the first no longer believes. The key is written before the certificate, so an interruption never leaves something that looks finished.
2026-09-29 14:06:31 +00:00 · 2026-09-29 15:42:51 +02:00 · 2026-09-29 15:07:33 +02:00 · 2026-09-29 11:30:34 +00:00 · 2026-09-29 13:30:32 +02:00 · 2026-09-29 10:30:32 +00:00
164 changed files with 16075 additions and 2427 deletions
@@ -86,13 +86,19 @@ proxy-image:

 # The whole gate. Raises a database, runs everything against it, and takes it down again --
 # including when the tests fail, which is why the teardown is not conditional.
+#
+# **One package at a time (-p 1), and it is not about speed.** The live tests reach one bus, and on
+# it they assert, read and remove the mesh's own objects -- streams and consumers with fixed names,
+# because those names are the mesh's and a test cannot choose others. Two packages doing that at once
+# is one deleting a consumer the other is reading through, and the failure lands in whichever test
+# was reading, as "no response from stream". That reads as a bug in the code under test.
 check: fmt vet postgres
-	@go test ./... ; status=$$? ; $(MAKE) postgres-stop ; exit $$status
+	@go test -p 1 ./... ; status=$$? ; $(MAKE) postgres-stop ; exit $$status

 # Without a database the live tests skip rather than fail, so this is the honest subset and not
-# the gate.
+# the gate. Serialised for the same reason check is: a bus may be configured even when a store is not.
 test:
-	go test ./...
+	go test -p 1 ./...

 vet:
 	go vet ./...
@@ -17,22 +17,15 @@ package main

 import (
 	"context"
-	"crypto/sha256"
-	"crypto/tls"
-	"crypto/x509"
-	"encoding/hex"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"net/url"
 	"os"
 	"os/signal"
 	"strings"
 	"syscall"
-	"time"
-
-	amqp "github.com/rabbitmq/amqp091-go"

+	"github.com/novox/mesh-controller/internal/broker"
 	"github.com/novox/mesh-controller/internal/builder"
 	"github.com/novox/mesh-controller/internal/link"
 )
@@ -52,7 +45,6 @@ const usage = `mesh-builder — builds modules for the mesh
 It consumes build requests and answers with what it made. Nothing is listened on and nothing
 is dialled except the broker.

-  MESH_BROKER_AMQP   where the broker is, with this builder's own credential
  MESH_BROKER_FILE   a file the mesh sealed to this machine holding the same
  MESH_REGISTRY      host:port to publish artifacts to, when the mesh has not said
  MESH_BINDING       a file the mesh wrote saying where the artifact store is
@@ -115,72 +107,48 @@ func run() error {
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer stop()

-	conn, err := dial(credential)
-	if err != nil {
-		// Not quoted back: the URL carries this builder's broker password.
-		return fmt.Errorf("cannot reach the broker: %w", err)
-	}
-	defer conn.Close()
-	channel, err := conn.Channel()
-	if err != nil {
-		return err
-	}
-	defer channel.Close()
-
-	if _, err := channel.QueueDeclare(link.BuildQueue, true, false, false, false, nil); err != nil {
-		return err
-	}
-	// One at a time. A build machine that took five requests at once would run five container
-	// builds against one runtime and finish all of them slower than it would have finished the
-	// first — and the queue is what shares work between machines, so nothing is lost by it.
-	if err := channel.Qos(1, 0, false); err != nil {
-		return err
-	}
-
-	// Not auto-acknowledged. A request acknowledged on arrival is a build that vanishes if this
-	// process dies mid-way, with nobody waiting on it ever hearing why.
-	requests, err := channel.ConsumeWithContext(ctx, link.BuildQueue, "mesh-builder",
-		false, false, false, false, nil)
+	machine, err := takeWorkFrom(credential, on)
 	if err != nil {
 		return err
 	}
+	defer machine.Close()

 	fmt.Fprintf(os.Stderr, "building for the mesh, publishing to %s\n", registry)
 	publisher := builder.Registry{Address: registry, Run: builder.Command}

-	for {
-		select {
-		case <-ctx.Done():
-			fmt.Println("stopping")
-			return nil
-		case delivery, ok := <-requests:
-			if !ok {
-				return fmt.Errorf("the broker closed the connection")
-			}
-			answer(ctx, channel, publisher, on, workspace, delivery)
-		}
+	return machine.Take(ctx, func(ctx context.Context, work link.Build) {
+		answer(ctx, publisher, on, workspace, work)
+	})
+}
+
+// takeWorkFrom opens this machine's link to whichever bus the mesh is on.
+//
+// **One place chooses**, as everywhere else the bus change went (novox/hq ADR 0116 step 5): a build
+// machine told about both would take work from one and answer on the other, and every log line would
+// say it was fine.
+func takeWorkFrom(credential Credential, on string) (link.BuildMachine, error) {
+	// **The credential names the bus, and there is one** (novox/hq ADR 0131, design 28 task 5.5).
+	// A credential for the mesh's bus carries user, password and fingerprint beside the address,
+	// and that is enough to dial it, pinned.
+	if !credential.onTheNewBus() {
+		return nil, fmt.Errorf("the credential at hand names %q, which is not the mesh's bus", credential.URL)
 	}
+	js, err := broker.DialPinned(credential.natsURL(), credential.Fingerprint)
+	if err != nil {
+		return nil, err
+	}
+	return link.MachineOverNATS(js, on), nil
 }

 // answer does one build and says what happened, whichever way it went.
-func answer(ctx context.Context, channel *amqp.Channel, publisher builder.Publisher,
-	on, workspace string, delivery amqp.Delivery) {
+func answer(ctx context.Context, publisher builder.Publisher, on, workspace string, work link.Build) {
+	request := work.Request()

-	// **First thing, and to stdout.** A build request that arrives and produces no visible line
-	// until it either finishes or fails is indistinguishable from one that never arrived — which
-	// cost a long diagnosis against a running mesh, chasing "the handler never fired" when the
-	// truth was only that the handler said nothing until the end.
-	fmt.Fprintf(os.Stderr, "a build request arrived (%d bytes)\n", len(delivery.Body))
-
-	var request link.BuildRequest
-	if err := json.Unmarshal(delivery.Body, &request); err != nil {
-		// Unreadable. Acknowledged and dropped rather than requeued: a message this builder
-		// cannot parse will not become parseable by being delivered again, and requeueing it
-		// would put it in front of every real request for ever.
-		fmt.Fprintf(os.Stderr, "a request could not be read and was dropped: %v\n", err)
-		_ = delivery.Ack(false)
-		return
-	}
+	// **First thing, and to stdout.** A build request that arrives and produces no visible line until
+	// it either finishes or fails is indistinguishable from one that never arrived — which cost a long
+	// diagnosis against a running mesh, chasing "the handler never fired" when the truth was only that
+	// the handler said nothing until the end.
+	fmt.Fprintf(os.Stderr, "a build request arrived for %s\n", request.Repository)

 	result := link.BuildResult{
 		ID: request.ID, Repository: request.Repository, Path: request.Path,
@@ -199,8 +167,8 @@ func answer(ctx context.Context, channel *amqp.Channel, publisher builder.Publis
 	var built builder.Result
 	if err == nil {
 		// The package-registry credential is a build input, so it is resolved before the clone: a
-		// build that could not have resolved its dependencies is refused in front of the reason,
-		// not after a clone that then fails at npm ci.
+		// build that could not have resolved its dependencies is refused in front of the reason, not
+		// after a clone that then fails at npm ci.
 		built, err = builder.Build(ctx, builder.Command, publisher,
 			request.Repository, request.Path, request.Ref, workspace, request.Held, npmrc,
 			forgeFrom(),
@@ -226,71 +194,26 @@ func answer(ctx context.Context, channel *amqp.Channel, publisher builder.Publis
 				})
 			}
 			result.Against = built.Against
+			for _, r := range built.Read {
+				result.Read = append(result.Read, link.ReadRepository{Repository: r.Repository, Ref: r.Ref})
+			}
 			fmt.Fprintf(os.Stderr, "  built %s from %s\n", built.Manifest.Module, short(built.Commit))
 		}
 	}

-	body, err := json.Marshal(result)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "cannot report a build: %v\n", err)
-		_ = delivery.Ack(false)
+	if err := work.Announce(ctx, result); err != nil {
+		// Said, not fatal: the build happened. A build reported as failed because announcing it
+		// failed is a lie about work that was done — and the request stays unsettled below only if
+		// nothing was said at all, so another machine can try.
+		fmt.Fprintf(os.Stderr, "cannot say what came of a build: %v\n", err)
 		return
 	}

-	// Always through the exchange, whether or not somebody is waiting.
-	//
-	// **Never the default exchange.** Permission there is granted per exchange rather than per
-	// queue, so a builder allowed to use it could publish into any node's queue — the privilege a
-	// build machine most obviously should not have. An asker binds its own reply queue to this
-	// key and filters by correlation; a control plane that records builds is bound to it too, so
-	// a result nobody asked for is still kept rather than reported into the void.
-	publishCtx, cancel := context.WithTimeout(ctx, 30*time.Second)
-	defer cancel()
-	if err := channel.PublishWithContext(publishCtx, link.Exchange, link.KeyBuilt, false, false,
-		amqp.Publishing{
-			ContentType:   "application/json",
-			CorrelationId: result.ID,
-			Body:          body,
-		}); err != nil {
-		fmt.Fprintf(os.Stderr, "cannot answer a build request: %v\n", err)
+	// Settled only once the outcome is away, so a machine that dies before answering leaves the work
+	// for another rather than losing it.
+	if err := work.Done(); err != nil {
+		fmt.Fprintf(os.Stderr, "the outcome is away and the request could not be settled: %v\n", err)
 	}
-	// **And announced, which is a different act from answering.** The reply goes to whoever asked
-	// and is correlated to their request; this says to the whole mesh that a module now exists at
-	// a commit, and the catalogue places it in the module graph (novox/hq ADR 0072). A build
-	// nobody asked for still has to be announced, or the graph knows less than the registry does.
-	//
-	// Only on success: a failed build produced no module-version, and announcing one would put
-	// something in the graph that was never made.
-	if result.Failed == "" && result.Commit != "" {
-		announced := map[string]any{
-			"module": moduleOf(result.Manifest), "commit": result.Commit,
-			"repository": result.Repository, "path": result.Path, "ref": result.Ref,
-			"manifest": json.RawMessage(result.Manifest), "against": result.Against,
-			"made": result.Made,
-		}
-		if err := link.EmitEvent(publishCtx, channel, link.KeyModuleBuilt, "builder", on, announced); err != nil {
-			// Said, not fatal: the build happened and was answered. A module the catalogue has not
-			// heard of is a gap somebody can close; a build reported as failed because announcing
-			// it failed is a lie about work that was done.
-			fmt.Fprintf(os.Stderr, "  built, but could not announce it: %v\n", err)
-		}
-	}
-
-	// Acknowledged only once the answer is away, so a builder that dies before answering leaves
-	// the request for another machine rather than losing it.
-	_ = delivery.Ack(false)
-}
-
-// moduleOf reads the module's name out of the manifest it just built, which is the only place it is
-// authoritative — the request named a repository and a path, not a module.
-func moduleOf(manifest json.RawMessage) string {
-	var named struct {
-		Module string `json:"module"`
-	}
-	if err := json.Unmarshal(manifest, &named); err != nil {
-		return ""
-	}
-	return named.Module
 }

 // packagesFrom is where a build resolves the mesh's own published packages — the SDK above all
@@ -499,13 +422,8 @@ func brokerFrom() (Credential, error) {
 		// broker is then verified against whatever this machine already trusts.
 		return Credential{URL: said}, nil
 	}
-	url := strings.TrimSpace(os.Getenv("MESH_BROKER_AMQP"))
-	if url == "" {
-		return Credential{}, fmt.Errorf(
-			"neither MESH_BROKER_FILE nor MESH_BROKER_AMQP: a builder with no broker has " +
-				"nothing to build")
-	}
-	return Credential{URL: url}, nil
+	return Credential{}, fmt.Errorf(
+		"no MESH_BROKER_FILE: a build machine with no credential for the bus has nothing to build")
 }

 // Credential is what a build machine is given so it can reach the broker.
@@ -517,48 +435,24 @@ func brokerFrom() (Credential, error) {
 // **The same shape a node gets, for the same reason** (novox/hq ADR 0004): the fingerprint travels
 // out of band — here, sealed with the credential — and the endpoint is verified once at connect.
 type Credential struct {
-	URL string `json:"url"`
-	// Fingerprint is SHA-256 over the broker certificate's DER bytes, or empty to verify the
-	// ordinary way.
+	URL         string `json:"url"`
 	Fingerprint string `json:"fingerprint,omitempty"`
+	// User and Password ride beside the address on the bus being built (design 25): a credential
+	// embedded in a URL leaks into every log line that prints a connection, so the mesh seals them
+	// as two fields and this machine joins them once, here, to dial.
+	User     string `json:"user,omitempty"`
+	Password string `json:"password,omitempty"`
 }

-// dial opens the connection, pinning the broker's certificate when there is one to pin.
-func dial(held Credential) (*amqp.Connection, error) {
-	if held.Fingerprint == "" {
-		return amqp.Dial(held.URL)
-	}
-	return amqp.DialTLS(held.URL, pinning(held.Fingerprint))
-}
+// onTheNewBus is whether a credential is for the bus being built: its address says so, and the
+// mesh only ever seals such a credential with the user and password beside it.
+func (c Credential) onTheNewBus() bool { return strings.HasPrefix(strings.TrimSpace(c.URL), "nats://") }

-// pinning is a TLS configuration that trusts exactly one certificate.
-//
-// InsecureSkipVerify with a VerifyPeerCertificate is **pinning, not skipping**: the standard chain
-// check is replaced, not removed, and what replaces it is stricter — one certificate is accepted
-// rather than every certificate a public authority would sign.
-//
-// Its own function so a test can drive it against a real handshake. A pin check that is only ever
-// exercised through a broker is a pin check nothing tests.
-func pinning(fingerprint string) *tls.Config {
-	return &tls.Config{
-		InsecureSkipVerify: true,
-		VerifyPeerCertificate: func(raw [][]byte, _ [][]*x509.Certificate) error {
-			if len(raw) == 0 {
-				return errors.New("the broker presented no certificate")
-			}
-			// The leaf, and in the same spelling the mesh writes it — `sha256:` and 64 hex
-			// characters. Comparing a bare digest against a written fingerprint never matches,
-			// and the failure is indistinguishable from being pointed at the wrong broker.
-			sum := sha256.Sum256(raw[0])
-			got := "sha256:" + hex.EncodeToString(sum[:])
-			if got != fingerprint {
-				return fmt.Errorf(
-					"this is not the broker this builder was told about\n  expected %s\n  "+
-						"got      %s\nEither this mesh's broker was replaced, or this builder is "+
-						"being pointed at something else. Retrying will not help",
-					fingerprint, got)
-			}
-			return nil
-		},
+// natsURL is the address with this machine's credential in it, for the one dial that needs it.
+func (c Credential) natsURL() string {
+	rest := strings.TrimPrefix(strings.TrimSpace(c.URL), "nats://")
+	if c.User == "" {
+		return "nats://" + rest
 	}
+	return "nats://" + c.User + ":" + c.Password + "@" + rest
 }
@@ -106,6 +106,9 @@ func buildOnce(ctx context.Context, args []string) error {
 		Manifest:   built.Manifest,
 		Against:    built.Against,
 	}
+	for _, r := range built.Read {
+		out.Read = append(out.Read, readRepository{Repository: r.Repository, Ref: r.Ref})
+	}
 	for _, made := range built.Built {
 		out.Made = append(out.Made, madeArtifact{Name: made.Name, Kind: made.Kind, Reference: made.Reference})
 	}
@@ -123,14 +126,21 @@ func buildOnce(ctx context.Context, args []string) error {
 // The same fields the mesh records for a build, so a reader comparing a genesis build against an
 // ordinary one is comparing the same thing said the same way.
 type onceResult struct {
-	Module     string         `json:"module"`
-	Commit     string         `json:"commit"`
-	Repository string         `json:"repository"`
-	Path       string         `json:"path,omitempty"`
-	Ref        string         `json:"ref,omitempty"`
-	Manifest   any            `json:"manifest"`
-	Made       []madeArtifact `json:"made"`
-	Against    []string       `json:"against,omitempty"`
+	Module     string           `json:"module"`
+	Commit     string           `json:"commit"`
+	Repository string           `json:"repository"`
+	Path       string           `json:"path,omitempty"`
+	Ref        string           `json:"ref,omitempty"`
+	Manifest   any              `json:"manifest"`
+	Made       []madeArtifact   `json:"made"`
+	Against    []string         `json:"against,omitempty"`
+	Read       []readRepository `json:"read,omitempty"`
+}
+
+// readRepository is a repository this build read source from besides the module's own.
+type readRepository struct {
+	Repository string `json:"repository"`
+	Ref        string `json:"ref,omitempty"`
 }

 type madeArtifact struct {
@@ -14,8 +14,8 @@ func TestBuilderDiagnosticsStayOffStdout(t *testing.T) {
 	allowed := map[string]bool{
 		"string(body)": true, // once.go: the result JSON, which IS stdout
 		"version)":     true, // --version
-		`"stopping")`: true,  // the loop.s shutdown line
-		"usage)":       true,  // --help text, for a human
+		`"stopping")`:  true, // the loop.s shutdown line
+		"usage)":       true, // --help text, for a human
 	}
 	for _, file := range []string{"once.go", "main.go"} {
 		src, err := os.ReadFile(file)
@@ -15,6 +15,8 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	"github.com/novox/mesh-controller/internal/broker"
 )

 // Where a builder publishes.
@@ -193,9 +195,9 @@ func TestThePinIsComparedInTheSpellingTheMeshWritesIt(t *testing.T) {
 	}
 }

-// handshakeWith runs the builder's own pin check against an address.
+// handshakeWith runs the pin check the builder dials with against an address.
 func handshakeWith(address, pin string) error {
-	conn, err := tls.Dial("tcp", address, pinning(pin))
+	conn, err := tls.Dial("tcp", address, broker.PinnedToFingerprint(pin))
 	if err != nil {
 		return err
 	}
@@ -17,8 +17,8 @@ import (

 var aDigest = "sha256:" + strings.Repeat("e", 64)

-// **A build is recorded by digest and path**, whatever address the builder pushed to — and only
-// what the build made is rewritten: an image the module runs from elsewhere is left where it says.
+// **A build is recorded by digest and path**, whatever address the builder pushed to — what it
+// made and what it stood on both; an image the module runs from elsewhere is left where it says.
 func TestABuildIsRecordedWithoutTheStoresAddress(t *testing.T) {
 	manifest, _ := json.Marshal(map[string]any{
 		"module": "gitea", "version": "1",
@@ -65,8 +65,11 @@ func TestABuildIsRecordedWithoutTheStoresAddress(t *testing.T) {
 	if strings.Contains(string(kept.Manifest), "anchor.internal:5100") {
 		t.Errorf("the recorded manifest still carries the store's address:\n%s", kept.Manifest)
 	}
-	if kept.Against[0] != "anchor.internal:5100/mesh-tools/runtime@"+aDigest {
-		t.Errorf("what the build stood on was rewritten: %v", kept.Against)
+	// What the build stood on is an edge to another module's artifact, and it is recorded the way
+	// that artifact is: by path in the store, so the edge still names the same thing when the
+	// store answers at another address.
+	if kept.Against[0] != catalogue.ArtifactStoreScheme+"mesh-tools/runtime@"+aDigest {
+		t.Errorf("what the build stood on was recorded by address: %v", kept.Against)
 	}
 }

@@ -88,7 +88,7 @@ func reportsReaching(t *testing.T, open *stores, reachable []link.Reach, held ..
 	if err := open.inventory.RecordSent(ctx, record.ID, digestOf(body)); err != nil {
 		t.Fatal(err)
 	}
-	if err := (link.Enrolment{Inventory: open.inventory}).Heard(ctx, link.Report{
+	if _, err := (link.Enrolment{Inventory: open.inventory}).Heard(ctx, link.Report{
 		Node: "anchor", Applied: []string{"hello-web.x"}, Declared: digestOf(body),
 		Firewall: "ufw", Held: held, Reachable: reachable,
 	}); err != nil {
@@ -309,7 +309,7 @@ func converge(ctx context.Context, open *stores, node string, yes bool, digest s
 		return "", err
 	}
 	derived := derivedFilter{rules: rules, foundation: with.Foundation, mesh: with.Mesh,
-		outward: plan.PublicDomain != ""}
+		outward: plan.PublicDomain != "", outwardLinks: with.OutwardLinks}
 	preview, saw := previewOf(node, reported, derived, plan, taken, filter, runs[filter])
 	preview += "\n\n  preview " + saw
 	if !yes {
@@ -414,6 +414,18 @@ func previewOf(node string, reported inventory.Adoption, derived derivedFilter,
 	b.WriteString("    not previewed: traffic the machine routes that is not a published port " +
 		"(a tunnel, NAT in the found firewall) — the derived filter drops it unless a module " +
 		"declares it\n")
+	// Which links the filter constrains, said rather than left to the sentence above (novox/hq ADR
+	// 0140). Everything arriving anywhere else is this machine's own guest and keeps working — which
+	// is what a reader most wants to know, because the previous shape of this filter cut a machine's
+	// guests off at the flip without saying so, and that is how this was found.
+	if len(derived.outwardLinks) > 0 {
+		b.WriteString(fmt.Sprintf("    it filters what arrives on: %s, and on the private network "+
+			"— everything its own guests send keeps working\n",
+			strings.Join(derived.outwardLinks, ", ")))
+	} else {
+		b.WriteString("    it has reported no link facing outside, so no filter can be composed " +
+			"for it — the flip is refused until it reports one\n")
+	}

 	isTaken := map[string]bool{}
 	for _, m := range taken {
@@ -473,6 +485,10 @@ type derivedFilter struct {
 	// mesh is every address on the private network; outward says the machine faces outside.
 	mesh    []string
 	outward bool
+	// outwardLinks is the links this machine reported as facing outside it (novox/hq ADR 0140).
+	// The filter constrains what arrives on them; everything arriving elsewhere is this machine's
+	// own guest and is not filtered.
+	outwardLinks []string
 }

 // closesOutside is what a narrowing from everywhere to the private network is called: it closes.
@@ -498,6 +514,12 @@ func (d derivedFilter) fate(r inventory.Reach) string {
 			return "stays open — the mesh's own, from anywhere"
 		}
 	}
+	// This machine's own guests ask it for an address and for names, and those two arrive here
+	// (novox/hq ADR 0140). Admitted by the link they arrive on, so a listener bound anywhere but an
+	// outward link keeps answering them.
+	if (r.Protocol == "udp" && (r.Port == 53 || r.Port == 67)) || (r.Protocol == "tcp" && r.Port == 53) {
+		return "stays open — this machine's own guests asking it for an address and for names"
+	}
 	for _, rule := range d.rules {
 		if rule.Port != r.Port || rule.Protocol != r.Protocol {
 			continue
@@ -37,13 +37,13 @@ func askCommand(ctx context.Context, args []string) error {
 		arguments = json.RawMessage(positionals[2])
 	}

-	server, err := link.Connect(nil, nil)
+	server, err := connectLink(ctx, nil, nil, nil)
 	if err != nil {
 		return err
 	}
 	defer server.Close()

-	answer, err := link.Ask(ctx, server.Channel(), module, tool, arguments, *wait)
+	answer, err := link.Ask(ctx, server.Bus(), module, tool, arguments, *wait)
 	if err != nil {
 		return err
 	}
@@ -2,8 +2,6 @@ package main

 import (
 	"context"
-	"crypto/rand"
-	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"flag"
@@ -31,6 +29,51 @@ import (
 // control plane may send a machine is bounded by the declaration language. This is the shape the
 // builder module will take when it is given work over the broker; today a person runs it, and the
 // mesh records the result the same way either way.
+// buildOn rebuilds every module the mesh holds that stands on the named module's artifacts — the
+// rebuild a changed base needs, which nothing else asks for: their sources did not move, and
+// "behind" does not see a base that did (novox/hq 04-ISSUES/131). Bases first among them too.
+func buildOn(ctx context.Context, base string, wait time.Duration) error {
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+	held, err := open.inventory.Catalogued(ctx)
+	if err != nil {
+		return err
+	}
+	against, err := open.inventory.BuiltAgainst(ctx)
+	if err != nil {
+		return err
+	}
+	var on []inventory.Entry
+	for _, e := range held {
+		if standsOnModule(e, base, against) {
+			on = append(on, e)
+		}
+	}
+	if len(on) == 0 {
+		fmt.Printf("nothing the mesh holds stands on %s\n", base)
+		return nil
+	}
+	on = orderByBases(on, against)
+	fmt.Printf("%d module(s) stand on %s:\n", len(on), base)
+	var failed []string
+	for _, e := range on {
+		fmt.Printf("--- %s\n", e.Manifest.Module)
+		source := buildSource{Repository: e.Source.Repository, Seat: e.Source.Seat}
+		if err := buildOne(ctx, source, e.Source.Path, e.Source.Ref, wait); err != nil {
+			fmt.Printf("  %v\n", err)
+			failed = append(failed, e.Manifest.Module)
+		}
+	}
+	if len(failed) > 0 {
+		return fmt.Errorf("%d of %d could not be built: %s", len(failed), len(on), strings.Join(failed, ", "))
+	}
+	fmt.Printf("\n%d module(s) rebuilt on %s. `push --behind` sends them on\n", len(on), base)
+	return nil
+}
+
 func buildCommand(ctx context.Context, args []string) error {
 	set := flag.NewFlagSet("build", flag.ContinueOnError)
 	ref := set.String("ref", "", "the branch, tag or commit to build")
@@ -46,6 +89,7 @@ func buildCommand(ctx context.Context, args []string) error {
 	// retype each repository is asking them to be the loop. Naming a repository and asking which
 	// ones need building are different requests, so they are not combined.
 	behind := set.Bool("behind", false, "every module the mesh holds older than its source has")
+	on := set.String("on", "", "rebuild every module that stands on this module's artifacts — the rebuild a changed base needs")
 	// A repository on the mesh's own forge, named by its path there (novox/hq ADR 0111). Without it
 	// the repository is external, cloned exactly as given — see source.go.
 	self := set.Bool("self", false, "the repository is a path on the forge holding the git seat")
@@ -53,6 +97,13 @@ func buildCommand(ctx context.Context, args []string) error {
 	if err != nil {
 		return err
 	}
+	if *on != "" {
+		if len(positionals) != 0 || *behind || *self {
+			return errors.New("build --on <module> names a base and nothing else")
+		}
+		return buildOn(ctx, *on, *wait)
+	}
+
 	if *behind {
 		if len(positionals) != 0 || *self {
 			return errors.New("build <repository> or build --behind, not both: one names a " +
@@ -61,7 +112,7 @@ func buildCommand(ctx context.Context, args []string) error {
 		return buildBehind(ctx, *wait)
 	}
 	if len(positionals) != 1 {
-		return errors.New("build <repository> [--self] [--path P] [--ref R] [--wait D] [--dry-run]")
+		return errors.New("build <repository> [--self] [--path P] [--ref R] [--wait D] [--dry-run]  |  build --behind  |  build --on <module>")
 	}
 	source := buildSource{Repository: positionals[0]}
 	if *self {
@@ -81,8 +132,9 @@ func buildCommand(ctx context.Context, args []string) error {
 //
 // **By digest and path, never by where it was pushed** (novox/hq 04-ISSUES/102). The builder
 // says `<registry>:<port>/<module>/<artifact>@sha256:…`; the mesh records the artifact-store
-// reference and composes the store's address back in where a reference is used. `against` is kept
-// as announced: it is what the build stood on as the builder saw it, and the catalogue's edge.
+// reference and composes the store's address back in where a reference is used. `against` — what
+// the build stood on, the catalogue's edge — is recorded the same way, so an edge names a module's
+// artifact and not the machine it was pulled from.
 func buildFrom(result link.BuildResult) inventory.Build {
 	kept := inventory.Build{
 		ID: result.ID, Repository: result.Repository, Ref: result.Ref,
@@ -92,7 +144,13 @@ func buildFrom(result link.BuildResult) inventory.Build {
 		// edges, and it is not always listening when a build happens — on a fresh mesh it cannot
 		// be, for exactly the modules it needs most. Keeping them is what makes a replay able to
 		// rebuild the graph rather than a list of names.
-		Path: result.Path, Against: result.Against,
+		Path: result.Path,
+	}
+	for _, ref := range result.Against {
+		kept.Against = append(kept.Against, catalogue.Recorded(ref))
+	}
+	for _, r := range result.Read {
+		kept.Read = append(kept.Read, inventory.ReadRepository{Repository: r.Repository, Ref: r.Ref})
 	}
 	var announced []inventory.Artifact
 	for _, made := range result.Made {
@@ -206,85 +264,45 @@ func builderCommand(ctx context.Context, args []string) error {
 	}
 	name := positionals[1]

-	management, err := broker.ManagementFromEnvironment()
+	// **The build machine's credential is a module's credential** (novox/hq ADR 0131, design 28
+	// task 5.5): minted into the mesh's records and sealed to the machine as the builder module's
+	// broker secret, usable at the next push — the same act `module issue` performs, and the same
+	// account the composed user list carries. Nothing is created on a server; the bus reads the list.
+	open, err := openStores(ctx)
 	if err != nil {
 		return err
 	}
-
-	// The same shape of secret a token carries: enough entropy that guessing is not a strategy,
-	// and safe to put in a URL because that is where it goes.
-	raw := make([]byte, 32)
-	if _, err := rand.Read(raw); err != nil {
+	defer open.Close()
+	inv := open.inventory
+	shelf, err := inv.Catalogue(ctx)
+	if err != nil {
 		return err
 	}
-	password := base64.RawURLEncoding.EncodeToString(raw)
-	if err := management.CreateBuilderAccount(ctx, name, password); err != nil {
+	m, known := shelf[*module]
+	if !known {
+		return fmt.Errorf("%s is not in the catalogue; `module add` it first", *module)
+	}
+	fmt.Printf("build machine %s: ", name)
+	node := *forNode
+	if node == "" {
+		entries, err := inv.Catalogued(ctx)
+		if err != nil {
+			return err
+		}
+		for _, e := range entries {
+			if e.Manifest.Module == *module && len(e.On) > 0 {
+				node = e.On[0]
+			}
+		}
+	}
+	if node == "" {
+		return fmt.Errorf("%s is assigned nowhere; `assign <machine> %s` first, or say --node", *module, *module)
+	}
+	address, err := broker.BusAddress()
+	if err != nil {
 		return err
 	}
-
-	fmt.Printf("broker account %s created, scoped to the %s queue and the %s exchange\n\n",
-		name, link.BuildQueue, link.Exchange)
-
-	if *forNode != "" {
-		known, err := broker.FromEnvironment()
-		if err != nil {
-			return fmt.Errorf("cannot deliver a credential without knowing where the broker is: %w", err)
-		}
-		inv, err := openInventory(ctx)
-		if err != nil {
-			return err
-		}
-		defer inv.Close()
-
-		brokerAddr, err := brokerReachableAt(ctx, inv, known, *forNode)
-		if err != nil {
-			return err
-		}
-
-		// The URL and what verifies the broker, together. A mesh's broker presents a certificate
-		// of the mesh's own, which is in no public trust store — so a URL on its own reaches only
-		// a broker somebody else vouches for, and the connection fails at TLS with an error about
-		// an unknown authority rather than about a missing pin.
-		//
-		// **The same two facts a node's token carries** (novox/hq ADR 0004), delivered the same
-		// way: out of band relative to the broker, so what is trusted does not come from the thing
-		// being trusted.
-		held, err := json.Marshal(struct {
-			URL         string `json:"url"`
-			Fingerprint string `json:"fingerprint,omitempty"`
-		}{
-			URL:         fmt.Sprintf("amqps://%s:%s@%s/", name, password, brokerAddr),
-			Fingerprint: known.Fingerprint,
-		})
-		if err != nil {
-			return err
-		}
-		if err := inv.AcceptSecretForModule(ctx, *forNode, *module, "broker", string(held)); err != nil {
-			return err
-		}
-		// Not printed. It is sealed to that machine and the mesh cannot read it back, which is
-		// the whole point — printing it here would put the one copy that matters on a terminal.
-		fmt.Printf("  sealed to %s, for the %s module. It arrives with the next push.\n",
-			*forNode, *module)
-		fmt.Printf("  run `push %s` to send it\n", *forNode)
-		return nil
-	}
-
-	// The whole line only when the address is known. A URL with a placeholder where the host
-	// should be is a URL somebody pastes and then debugs, and the placeholder is the last thing
-	// they look at.
-	if known, err := broker.FromEnvironment(); err == nil {
-		fmt.Printf("  MESH_BROKER_AMQP=amqps://%s:%s@%s/\n\n", name, password, known.Address)
-	} else {
-		fmt.Printf("  the password is %s\n\n", password)
-		fmt.Printf("  This control plane has no %s, so it cannot say where the broker is.\n"+
-			"  Put the password in MESH_BROKER_AMQP on the build machine.\n\n",
-			broker.AddressVar)
-	}
-	// Shown once, like a token, and for the same reason: what is stored is the broker's own hash
-	// of it, and a control plane that could show it back would be a control plane that holds it.
-	fmt.Println("This is the only time it is shown.")
-	return nil
+	return issueOnTheNewBus(ctx, inv, m, node, address)
 }

 // buildBehind builds every module the mesh holds older than its source has.
@@ -329,6 +347,14 @@ func buildBehind(ctx context.Context, wait time.Duration) error {
 	}
 	fmt.Println()

+	// Bases first: a module built before the module it stands on is built against the old one
+	// and reports success (novox/hq 04-ISSUES/131).
+	against, err := inv.BuiltAgainst(ctx)
+	if err != nil {
+		return err
+	}
+	stale = orderByBases(stale, against)
+
 	var failed []string
 	for _, e := range stale {
 		fmt.Printf("--- %s\n", e.Manifest.Module)
@@ -368,7 +394,7 @@ func buildOne(ctx context.Context, source buildSource, path, ref string, wait ti
 	}
 	defer ident.Close()

-	server, err := link.Connect(nil, nil)
+	server, err := connectLink(ctx, nil, nil, nil)
 	if err != nil {
 		return err
 	}
@@ -395,7 +421,13 @@ func buildOne(ctx context.Context, source buildSource, path, ref string, wait ti
 	}
 	fmt.Println()

-	result, err := link.RequestBuild(ctx, server.Channel(), request, wait)
+	ask, err := askOver(server)
+	if err != nil {
+		return err
+	}
+	defer ask.Close()
+
+	result, err := ask.Submit(ctx, request, wait)
 	if err != nil {
 		return err
 	}
@@ -466,13 +498,19 @@ func buildAndShow(ctx context.Context, source buildSource, path, ref string, wai
 		return err
 	}
 	defer ident.Close()
-	server, err := link.Connect(nil, nil)
+	server, err := connectLink(ctx, nil, nil, nil)
 	if err != nil {
 		return err
 	}
 	defer server.Close()

-	result, err := link.RequestBuild(ctx, server.Channel(), link.BuildRequest{
+	ask, err := askOver(server)
+	if err != nil {
+		return err
+	}
+	defer ask.Close()
+
+	result, err := ask.Submit(ctx, link.BuildRequest{
 		ID:         fmt.Sprintf("%s-%d", "build", time.Now().UnixNano()),
 		Repository: repository, Path: path, Ref: ref,
 		Held: heldBy(ctx),
@@ -557,3 +595,16 @@ func heldBy(ctx context.Context) map[string]string {
 	}
 	return routed
 }
+
+// askOver opens the way a build is asked for, on whichever bus the mesh is on.
+//
+// **One place chooses**, as everywhere else the bus change went (novox/hq ADR 0116 step 5). On the bus
+// the mesh runs on today this needs the controller's own connection, so it is handed one; on the bus
+// being built it dials, because a build request is a one-shot and holds nothing else.
+func askOver(_ *link.Server) (link.Builders, error) {
+	address, err := broker.BusAddress()
+	if err != nil {
+		return nil, err
+	}
+	return link.BuildsOverNATS(address)
+}
@@ -0,0 +1,171 @@
+package main
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"math/big"
+	"net"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+// The bus's own certificate, made by the mesh rather than borrowed from an image.
+//
+// **The foundation asked a third-party image for a tool it never said must be there** (novox/hq
+// 04-ISSUES/146). The bootstrap made this certificate by running `openssl` inside the broker's
+// image, which worked while the broker was one that happened to carry it and stopped the day the
+// bus changed: the new one has a shell and no openssl, so the step exited 127 and no mesh could be
+// raised. Substituting another image the bundle names does not help — none of them carry it
+// either.
+//
+// So the program that needs a certificate makes one. It is the mesh's own binary, already on the
+// machine at this point in the bootstrap (the schema step ran it), and it needs nothing from the
+// image it writes into but a mounted directory.
+//
+// **Self-signed, and that is the design** — a host pins this server's exact certificate and
+// authenticates with a password (novox/hq ADR 0004). There is no authority above it to ask, and at
+// this moment in a bootstrap there is no mesh to ask one of.
+//
+// Idempotent, because the step is applied again on every reconcile and a second certificate would
+// be one the hosts that pinned the first no longer believe.
+
+// busCertificateNames is what the bus is reached by: the container name on a mesh network, and the
+// loopback address the machine's own foundation dials.
+var busCertificateNames = []string{"mesh-broker"}
+
+const busCertificateLife = 10 * 365 * 24 * time.Hour
+
+// busCertificate makes the bus's certificate in a directory, or says whether one is there.
+//
+//	broker certificate --into /tls           make it if it is not there
+//	broker certificate --check --into /tls   exit non-zero unless a usable pair is
+func busCertificate(args []string) error {
+	into, check := "", false
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--check":
+			check = true
+		case "--into":
+			if i+1 >= len(args) {
+				return errors.New("--into needs a directory")
+			}
+			into = args[i+1]
+			i++
+		default:
+			return fmt.Errorf("broker certificate [--check] --into <directory>: %q", args[i])
+		}
+	}
+	if into == "" {
+		return errors.New("broker certificate [--check] --into <directory>")
+	}
+	crt, key := filepath.Join(into, "tls.crt"), filepath.Join(into, "tls.key")
+
+	if usable, err := busCertificateUsable(crt, key); err != nil {
+		return err
+	} else if usable {
+		fmt.Printf("the bus already has a certificate at %s, and it was left alone\n", crt)
+		return nil
+	}
+	if check {
+		// Said as a failure, because that is what the caller asked: a bootstrap's verify runs
+		// this and a false answer is what makes the step run.
+		return fmt.Errorf("no usable certificate and key at %s", into)
+	}
+	return writeBusCertificate(crt, key)
+}
+
+// busCertificateUsable says whether a certificate and its key are both there and parse.
+//
+// Both, and parsed rather than stat'ed: a half-written pair is the state a bootstrap interrupted
+// between the two files leaves behind, and a step that treated it as done would hand the server a
+// certificate with no key and report success.
+func busCertificateUsable(crt, key string) (bool, error) {
+	certPEM, err := os.ReadFile(crt)
+	if errors.Is(err, os.ErrNotExist) {
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	keyPEM, err := os.ReadFile(key)
+	if errors.Is(err, os.ErrNotExist) {
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	if _, err := tlsPairParses(certPEM, keyPEM); err != nil {
+		return false, nil
+	}
+	return true, nil
+}
+
+func tlsPairParses(certPEM, keyPEM []byte) (*x509.Certificate, error) {
+	block, _ := pem.Decode(certPEM)
+	if block == nil || block.Type != "CERTIFICATE" {
+		return nil, errors.New("not a certificate")
+	}
+	certificate, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		return nil, err
+	}
+	keyBlock, _ := pem.Decode(keyPEM)
+	if keyBlock == nil {
+		return nil, errors.New("not a key")
+	}
+	if _, err := x509.ParsePKCS8PrivateKey(keyBlock.Bytes); err != nil {
+		if _, err := x509.ParsePKCS1PrivateKey(keyBlock.Bytes); err != nil {
+			return nil, err
+		}
+	}
+	return certificate, nil
+}
+
+func writeBusCertificate(crt, key string) error {
+	private, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		return err
+	}
+	serial, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	if err != nil {
+		return err
+	}
+	template := &x509.Certificate{
+		SerialNumber:          serial,
+		Subject:               pkix.Name{CommonName: busCertificateNames[0]},
+		DNSNames:              busCertificateNames,
+		IPAddresses:           []net.IP{net.ParseIP("127.0.0.1")},
+		NotBefore:             time.Now().Add(-time.Hour),
+		NotAfter:              time.Now().Add(busCertificateLife),
+		KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+	}
+	der, err := x509.CreateCertificate(rand.Reader, template, template, &private.PublicKey, private)
+	if err != nil {
+		return err
+	}
+	pkcs8, err := x509.MarshalPKCS8PrivateKey(private)
+	if err != nil {
+		return err
+	}
+
+	// **The key first, and only then the certificate**, so the pair a reader finds is never a
+	// certificate whose key has not been written yet — the one order in which an interruption
+	// leaves something that looks finished (novox/hq 04-ISSUES/014, a key present and unusable).
+	if err := os.WriteFile(key, pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: pkcs8}), 0o600); err != nil {
+		return err
+	}
+	if err := os.WriteFile(crt, pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der}), 0o644); err != nil {
+		return err
+	}
+	fmt.Printf("made the bus a certificate for %v, valid until %s\n  %s\n  %s\n",
+		busCertificateNames, template.NotAfter.Format(time.RFC3339), crt, key)
+	return nil
+}
@@ -0,0 +1,121 @@
+package main
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// novox/hq 04-ISSUES/146. The bootstrap could not make the bus a certificate: it asked an image for
+// `openssl` and the image it asks has none. What replaces it is this command, so what is checked is
+// what the bootstrap needs from it — a pair a TLS server can actually load, made once and only once.
+
+func TestTheBusCertificateLoadsAsAServersWould(t *testing.T) {
+	into := t.TempDir()
+	if err := busCertificate([]string{"--into", into}); err != nil {
+		t.Fatalf("the bus could not be given a certificate: %v", err)
+	}
+
+	// The check a cheaper test would not make. The key was present and valid and the server could
+	// not start, once, because nothing loaded the pair the way a server loads it
+	// (novox/hq 04-ISSUES/014).
+	pair, err := tls.LoadX509KeyPair(filepath.Join(into, "tls.crt"), filepath.Join(into, "tls.key"))
+	if err != nil {
+		t.Fatalf("a TLS server cannot load what was written: %v", err)
+	}
+	leaf := pair.Leaf
+	if leaf == nil {
+		if leaf, err = x509.ParseCertificate(pair.Certificate[0]); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := leaf.VerifyHostname("mesh-broker"); err != nil {
+		t.Errorf("the certificate is not for the name the bus is reached by: %v", err)
+	}
+	if len(leaf.IPAddresses) == 0 || leaf.IPAddresses[0].String() != "127.0.0.1" {
+		t.Errorf("the certificate does not cover the loopback address the foundation dials: %v", leaf.IPAddresses)
+	}
+
+	// The key is not readable by anything else on the machine; the certificate is public and is.
+	key, err := os.Stat(filepath.Join(into, "tls.key"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if key.Mode().Perm() != 0o600 {
+		t.Errorf("the key is %v", key.Mode().Perm())
+	}
+	crt, err := os.Stat(filepath.Join(into, "tls.crt"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if crt.Mode().Perm() != 0o644 {
+		t.Errorf("the certificate is %v, which the server runs as another user cannot read", crt.Mode().Perm())
+	}
+}
+
+// **Made once.** The step is applied again on every reconcile, and a second certificate is one the
+// hosts that pinned the first no longer believe (novox/hq ADR 0004).
+func TestTheBusCertificateIsMadeOnce(t *testing.T) {
+	into := t.TempDir()
+	if err := busCertificate([]string{"--into", into}); err != nil {
+		t.Fatal(err)
+	}
+	first, err := os.ReadFile(filepath.Join(into, "tls.crt"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := busCertificate([]string{"--into", into}); err != nil {
+		t.Fatal(err)
+	}
+	again, err := os.ReadFile(filepath.Join(into, "tls.crt"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(first) != string(again) {
+		t.Fatal("running it twice replaced the certificate every host had pinned")
+	}
+}
+
+// The verify half: false before, true after, which is what makes the bootstrap run the step at all.
+func TestTheCheckIsFalseUntilThereIsAPair(t *testing.T) {
+	into := t.TempDir()
+	if err := busCertificate([]string{"--check", "--into", into}); err == nil {
+		t.Fatal("an empty directory reported a usable certificate")
+	}
+	if err := busCertificate([]string{"--into", into}); err != nil {
+		t.Fatal(err)
+	}
+	if err := busCertificate([]string{"--check", "--into", into}); err != nil {
+		t.Fatalf("the certificate it just made does not satisfy its own check: %v", err)
+	}
+}
+
+// A half-written pair is not a pair. An interrupted bootstrap leaves exactly this, and a step that
+// called it done would hand the server a certificate with no key and report success.
+func TestACertificateWithoutItsKeyIsNotUsable(t *testing.T) {
+	into := t.TempDir()
+	if err := busCertificate([]string{"--into", into}); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Remove(filepath.Join(into, "tls.key")); err != nil {
+		t.Fatal(err)
+	}
+	if err := busCertificate([]string{"--check", "--into", into}); err == nil {
+		t.Fatal("a certificate with no key passed the check")
+	}
+	if err := busCertificate([]string{"--into", into}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := tls.LoadX509KeyPair(filepath.Join(into, "tls.crt"), filepath.Join(into, "tls.key")); err != nil {
+		t.Fatalf("it did not replace the unusable pair: %v", err)
+	}
+}
+
+func TestWhereToWriteIsRequired(t *testing.T) {
+	if err := busCertificate(nil); err == nil || !strings.Contains(err.Error(), "--into") {
+		t.Fatalf("it did not ask where to write: %v", err)
+	}
+}
@@ -76,7 +76,10 @@ func run() error {
 		return pinCommand(ctx, args[1:], true)
 	case "unpin":
 		return pinCommand(ctx, args[1:], false)
-	case "migrate":
+	// `prepare` is how the mesh asks any module to bring its state to the shape this version needs
+	// (novox/hq ADR 0135), and the control plane answers it the same way as everything else — its
+	// own schema is not a special case. `migrate` remains the word a person types.
+	case "prepare", "migrate":
 		return migrate(ctx)
 	case "node":
 		return nodeCommand(ctx, args[1:])
@@ -114,8 +117,12 @@ func run() error {
 		return planCommand(ctx, args[1:])
 	case "push":
 		return pushCommand(ctx, args[1:])
+	case "rollout":
+		return rolloutCommand(ctx, args[1:])
 	case "seats":
 		return seatsCommand(ctx, args[1:])
+	case "seat":
+		return seatCommand(ctx, args[1:])
 	case "status":
 		return statusCommand(ctx, args[1:])
 	case "version":
@@ -134,12 +141,16 @@ func usage() {
 	fmt.Fprint(os.Stderr, `mesh-controller — the control plane

  migrate                        bring each context's schema up to date
+  prepare                        the same, asked the way the mesh asks any module (ADR 0135)
  node add <name> [--adopted]    create a node record; --adopted: the machine is in use
  node list                      the nodes this mesh knows about
  node show <name>               what one machine reported it can do, and why
  node public-domain <name>      the domain it composes its routed names under
  node public-domain <name> <d>  ...set it to d
  node public-domain <name> --clear   ...it faces the outside no longer
+  node networks <name>           the networks it routes for what it hosts
+  node networks <name> <cidr>... ...set them; its filter forwards these too
+  node networks <name> --clear   ...only the container runtime's own
  token issue --node <name>      a one-time right to join, for an existing record
  token issue --new <name>       create the record and issue for it
  token issue ... --adopted      ...for a machine in use, which joins adopted
@@ -180,6 +191,7 @@ func usage() {
  operator key show                         the operator key, and what it can recover
  build <repository> [--ref R]   have a build machine build it, and record what came out
  build --behind                 build every module the mesh holds older than its source
+  build --on <module>            rebuild every module that stands on this module's artifacts, bases first
  builds [<module>]              what has been built lately, and what came of it
  builder issue <name>           a broker account for a build machine, scoped to build work,
                                 delivered as the builder module's broker secret (module add it first)
@@ -2,8 +2,6 @@ package main

 import (
 	"context"
-	"crypto/rand"
-	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"flag"
@@ -71,12 +69,20 @@ func moduleCommand(ctx context.Context, args []string) error {
 		repo := set.String("source", "", "where this module comes from")
 		ref := set.String("ref", "", "the branch followed there")
 		commit := set.String("commit", "", "the commit this manifest was read at")
+		// **Where inside the repository the module is** (novox/hq ADR 0069). A module is a
+		// repository *and* a directory, and a record that carries only the repository names a
+		// module.json at its root — so every later build of it looks in the wrong place and fails
+		// with "no module.json at its root". Nine modules on this mesh were registered that way
+		// and none of them could be rebuilt (2026-09-28).
+		path := set.String("path", "", "the module's directory inside that repository")
+		self := set.Bool("self", false, "the source is a path on the forge holding the git seat")
 		positionals, err := parseAround(set, args[1:])
 		if err != nil {
 			return err
 		}
 		if len(positionals) != 1 {
-			return errors.New("module add <manifest.json> [--source <repo> --ref <branch> --commit <sha>]")
+			return errors.New("module add <manifest.json> [--source <repo> [--self] [--path P] " +
+				"--ref <branch> --commit <sha>]")
 		}
 		raw, err := os.ReadFile(positionals[0])
 		if err != nil {
@@ -86,23 +92,24 @@ func moduleCommand(ctx context.Context, args []string) error {
 		if err != nil {
 			return err
 		}
-		// Provenance together or not at all. A source with no commit cannot be compared against
-		// anything, so it would record where the module came from and still never be able to say
-		// the mesh is behind it — which is the one thing recording it is for.
-		if (*repo == "") != (*commit == "") {
-			return errors.New("--source and --commit go together: a source with no commit " +
-				"cannot be compared against anything, and a commit with no source has nothing " +
-				"to be compared with")
+		from, err := whereItComesFrom(*repo, *ref, *commit, *path, *self)
+		if err != nil {
+			return err
 		}
-		if err := inv.RegisterModule(ctx, m, inventory.Source{
-			Repository: *repo, Ref: *ref, BuiltFrom: *commit,
-		}); err != nil {
+		if err := inv.RegisterModule(ctx, m, from); err != nil {
 			return err
 		}
 		fmt.Printf("%s registered", m.Module)
 		if *commit != "" {
 			fmt.Printf(" from %s", short(*commit))
 		}
+		if *repo != "" && *path == "" {
+			// Said, not refused: a module really at the root is the ordinary case for a repository
+			// of its own. But a repository holding many modules and a record naming none of them is
+			// a module nothing can rebuild, and the person adding it is the one who knows which.
+			fmt.Printf("\n  no directory inside %s, so it is built from that repository's root — "+
+				"`--path` if the module lives in a directory there", *repo)
+		}
 		if len(m.Provides) > 0 {
 			fmt.Printf(", providing %s", describeOffers(m.Provides))
 		}
@@ -257,66 +264,15 @@ func moduleCommand(ctx context.Context, args []string) error {
 			return err
 		}

-		management, err := broker.ManagementFromEnvironment()
+		// Which bus this mesh is on. A module gets a credential for exactly one, and the two are
+		// made in entirely different ways: on the bus the mesh runs on today an account is a
+		// management call, and on the bus being built it is a row the next composition writes into
+		// the server's user list (novox/hq design 25 §4).
+		busAddress, err := broker.BusAddress()
 		if err != nil {
 			return err
 		}
-		// The foundation owns the bus; make sure it exists before a module binds onto it.
-		if err := management.EnsureEventExchanges(ctx); err != nil {
-			return err
-		}
-
-		secret := make([]byte, 32)
-		if _, err := rand.Read(secret); err != nil {
-			return err
-		}
-		password := base64.RawURLEncoding.EncodeToString(secret)
-		account, err := management.CreateModuleAccount(ctx, *forNode, module, password, m.Emits, m.Consumes)
-		if err != nil {
-			return err
-		}
-		// A consumer's queue, with its dead-letter, is the foundation's to declare — its own account
-		// may not (ADR 0043). Made now, so it exists before the module binds onto it.
-		if len(m.Consumes) > 0 {
-			if err := management.EnsureModuleQueue(ctx, *forNode, module); err != nil {
-				return err
-			}
-		}
-
-		known, err := broker.FromEnvironment()
-		if err != nil {
-			return fmt.Errorf("cannot deliver a credential without knowing where the broker is: %w", err)
-		}
-		brokerAddr, err := brokerReachableAt(ctx, inv, known, *forNode)
-		if err != nil {
-			return err
-		}
-		// The URL and what verifies the broker, together — a mesh's broker presents its own
-		// certificate, in no public trust store, so a URL alone fails at TLS (as `builder issue`).
-		held, err := json.Marshal(struct {
-			URL         string `json:"url"`
-			Fingerprint string `json:"fingerprint,omitempty"`
-			Node        string `json:"node"`
-			Module      string `json:"module"`
-		}{
-			URL:         fmt.Sprintf("amqps://%s:%s@%s/", account, password, brokerAddr),
-			Fingerprint: known.Fingerprint,
-			// The node and module the account is for, so the runtime names its queue as the mesh
-			// scoped it (<node>.<module>.events) without a manifest having to interpolate a node.
-			Node:   *forNode,
-			Module: module,
-		})
-		if err != nil {
-			return err
-		}
-		if err := inv.AcceptSecretForModule(ctx, *forNode, module, "broker", string(held)); err != nil {
-			return err
-		}
-		fmt.Printf("broker account %s created for %s, scoped to what it emits and consumes\n",
-			account, module)
-		fmt.Printf("  sealed to %s. It arrives with the next push — `push %s` to send it\n",
-			*forNode, *forNode)
-		return nil
+		return issueOnTheNewBus(ctx, inv, m, *forNode, busAddress)

 	default:
 		return fmt.Errorf("module has no %q; it has add, list, moved, forget and issue", args[0])
@@ -567,3 +523,125 @@ func mayIssue(m catalogue.Manifest) error {
 	}
 	return nil
 }
+
+// issueOnTheNewBus gives an assigned module its credential on the bus being built.
+//
+// **Three things differ from a management call, and each is the point of the move.** The credential
+// is minted into the mesh's records and becomes usable at the next composition, so there is no
+// server to be reachable for this to work. The password travels beside the address rather than inside
+// it, because the runtime's contract already separates them and a credential embedded in a URL is one
+// that leaks into every log line that prints a connection. And the module's durable consumer is
+// derived from what it declared rather than declared by name, so a module cannot ask for delivery of
+// something it did not say it consumes.
+func issueOnTheNewBus(ctx context.Context, inv *inventory.Inventory, m catalogue.Manifest,
+	node, busAddress string) error {
+
+	user := broker.Principal{Kind: broker.KindModule, Node: node, Module: m.Module}.Username()
+	password, err := inv.MintBusPassword(ctx, inventory.BusUser{
+		Username: user, Kind: inventory.BusModule, Node: node, Module: m.Module,
+	})
+	if err != nil {
+		return err
+	}
+
+	// Where the module is told to find the bus, and what certificate it must present. The same pair
+	// a node is told, for the same reason: a mesh's bus presents its own certificate, in no public
+	// trust store, so an address alone fails at TLS.
+	known, err := broker.FromEnvironment()
+	if err != nil {
+		return fmt.Errorf("cannot deliver a credential without knowing where the bus is: %w", err)
+	}
+	reachable, err := brokerReachableAt(ctx, inv, known, node)
+	if err != nil {
+		return err
+	}
+	return issueWith(ctx, inv, m, node, busAddress, known, reachable, user, password)
+}
+
+// issueWith is the delivery half: the minted password sealed to the machine as the module's broker
+// secret, and the module's consumer created where the bus can be reached. Split from the minting
+// so the move can issue every module against a bus whose address it worked out itself
+// (`rollout mint`, design 28 task 5.2) rather than the one in this process's environment.
+func issueWith(ctx context.Context, inv *inventory.Inventory, m catalogue.Manifest,
+	node, busAddress string, known broker.Broker, reachable, user, password string) error {
+	held, err := json.Marshal(struct {
+		URL         string `json:"url"`
+		Fingerprint string `json:"fingerprint,omitempty"`
+		Node        string `json:"node"`
+		Module      string `json:"module"`
+		User        string `json:"user"`
+		Password    string `json:"password"`
+	}{
+		URL: "nats://" + reachable, Fingerprint: known.Fingerprint,
+		Node: node, Module: m.Module, User: user, Password: password,
+	})
+	if err != nil {
+		return err
+	}
+	if err := inv.AcceptSecretForModule(ctx, node, m.Module, "broker", string(held)); err != nil {
+		return err
+	}
+
+	// And how it hears what it consumes. Derived from its declaration, and only when it declared
+	// something: a module that consumes nothing needs no consumer, and creating one would be a
+	// durable subscription nobody reads.
+	if consumer, needed := broker.ConsumerFor(broker.Principal{
+		Kind: broker.KindModule, Node: node, Module: m.Module,
+		Emits: m.Emits, Consumes: m.Consumes, Serves: m.Tools,
+	}); needed {
+		if busAddress == "" {
+			fmt.Printf("  %s consumes; its consumer is created when the bus is reachable (`push`, then "+
+				"`rollout mint` again is harmless)\n", m.Module)
+		} else {
+			js, err := broker.Dial(busAddress)
+			if err != nil {
+				return fmt.Errorf("the credential is minted and the mesh cannot reach the bus to create "+
+					"how %s hears what it consumes: %w", m.Module, err)
+			}
+			defer js.Close()
+			if err := js.EnsureConsumer(consumer); err != nil {
+				return err
+			}
+		}
+	}
+
+	fmt.Printf("bus user %s minted for %s, scoped to what it emits and consumes\n", user, m.Module)
+	fmt.Printf("  sealed to %s. It arrives with the next push — `push %s` to send it\n", node, node)
+	fmt.Printf("  and it works once the bus has been told: the user list is composed into the " +
+		"machine holding mesh-broker\n")
+	return nil
+}
+
+// whereItComesFrom is the provenance a module handed over by hand records, and what a record must
+// say to be worth anything later.
+//
+// **A module is a repository and a directory inside it** (novox/hq ADR 0069). A record carrying only
+// the repository names a module.json at its root, so every later build of it looks in the wrong
+// place — nine modules on this mesh were registered that way and none of them could be rebuilt
+// (2026-09-28). The directory cannot be checked from here, because the control plane does not clone;
+// what can be checked is that the record is whole.
+func whereItComesFrom(repository, ref, commit, path string, self bool) (inventory.Source, error) {
+	// Provenance together or not at all. A source with no commit cannot be compared against
+	// anything, so it would record where the module came from and still never be able to say the
+	// mesh is behind it — which is the one thing recording it is for.
+	if (repository == "") != (commit == "") {
+		return inventory.Source{}, errors.New("--source and --commit go together: a source with " +
+			"no commit cannot be compared against anything, and a commit with no source has " +
+			"nothing to be compared with")
+	}
+	// A directory or a forge with no repository is half a location, and the half it keeps is the
+	// half nothing can be found with.
+	if repository == "" && (path != "" || self) {
+		return inventory.Source{}, errors.New("--path and --self say where inside a source and " +
+			"which forge holds it, so they need --source: without one there is nothing for them " +
+			"to be part of")
+	}
+	from := inventory.Source{Repository: repository, Ref: ref, BuiltFrom: commit, Path: path}
+	if self {
+		if err := onASeat(repository); err != nil {
+			return inventory.Source{}, err
+		}
+		from.Seat = gitSeat
+	}
+	return from, nil
+}
@@ -256,7 +256,7 @@ func network(ctx context.Context, inv *inventory.Inventory, on map[string]bool,
 					"Re-place it — `overlay place %s --hub --endpoint <host>:%d …` — and push again; "+
 					"nothing was composed", p.Name, t.Interface, wrong, p.Name, t.Port)
 			}
-			n.TakesOver = &overlay.TakeOver{Interface: t.Interface, Unit: t.Unit, Config: t.Config, Port: t.Port}
+			n.TakesOver = &overlay.TakeOver{Interface: t.Interface, Unit: t.Unit, Config: t.Config, Port: t.Port, MTU: t.MTU}
 		}
 		if p.Hub {
 			for _, c := range carried {
@@ -537,6 +537,15 @@ func onTheNetwork(ctx context.Context, inv *inventory.Inventory,
 	if err != nil {
 		return nil, err
 	}
+	// **With the seat holders on record**, or a machine running the next holder of a seat beside
+	// the current one resolves as two holders, is refused, and drops out of the map — taking the
+	// address every other machine composes for what it offers (novox/hq ADR 0131). Found live:
+	// the control node vanished from the private network the moment the new bus was assigned
+	// beside the old one.
+	holdings, err := inv.Holdings(ctx)
+	if err != nil {
+		return nil, err
+	}
 	var out []inventory.Overlay
 	for _, p := range places {
 		if p.Address == "" {
@@ -549,7 +558,7 @@ func onTheNetwork(ctx context.Context, inv *inventory.Inventory,
 		caps, _ := inv.ProfileOf(ctx, p.Name)
 		got, err := catalogue.Resolve(shelf, assigned,
 			catalogue.Node{Name: p.Name, Site: p.Site, Capabilities: caps},
-			catalogue.World{Unchecked: true})
+			catalogue.World{Unchecked: true, Holdings: holdings})
 		if err != nil {
 			continue
 		}
@@ -10,7 +10,6 @@ import (

 	"github.com/novox/mesh-controller/internal/broker"
 	"github.com/novox/mesh-controller/internal/inventory"
-	"github.com/novox/mesh-controller/internal/link"
 	"github.com/novox/mesh-controller/internal/token"
 )

@@ -67,8 +66,26 @@ func nodeCommand(ctx context.Context, args []string) error {
 		// because the damage is already done by the time it prints.
 		return publicDomain(ctx, inv, args[1:])

+	case "networks":
+		// Removed by novox/hq ADR 0140, which superseded the record that added it. The filter no
+		// longer names any network: it constrains what arrives from outside the machine and says
+		// nothing about what did not, so there is no list to keep. Answered rather than met with
+		// "unknown command", because this was the documented way to stop a flip cutting a machine's
+		// containers off and somebody will reasonably still type it.
+		return errors.New("`node networks` is gone (novox/hq ADR 0140). The filter constrains what " +
+			"arrives from outside this machine and says nothing about traffic that did not, so no " +
+			"network is named anywhere and nothing needs to be said to keep a machine's own " +
+			"containers reaching outward. The machine reports which of its links face outside; see " +
+			"`node show <name>`")
+
+	case "account":
+		// The operator's login on this machine (novox/hq to-be 29): what a home-scoped file is
+		// owned by and which account `ssh <node>` uses. Reports with no argument; sets with one;
+		// an optional second argument is the home when it is not /home/<account>.
+		return nodeAccount(ctx, inv, args[1:])
+
 	default:
-		return fmt.Errorf("node has no %q; it has add, list, show and public-domain", args[0])
+		return fmt.Errorf("node has no %q; it has add, list, show, public-domain and account", args[0])
 	}
 }

@@ -106,6 +123,39 @@ func modeOf(n inventory.Node) string {
 }

 // publicDomainUsage is the one description of the three forms, so a refusal and the help agree.
+// nodeAccount reports or sets a node's operator account (novox/hq to-be 29). Read-shaped with no
+// argument, like public-domain: `node account novox` answers, it does not change anything.
+func nodeAccount(ctx context.Context, inv *inventory.Inventory, positionals []string) error {
+	if len(positionals) == 0 || len(positionals) > 3 {
+		return errors.New("node account <name> — what it is now; " +
+			"node account <name> <account> [home] — set it (home defaults to /home/<account>)")
+	}
+	node := positionals[0]
+	if len(positionals) == 1 {
+		who, err := inv.NodeByName(ctx, node)
+		if err != nil {
+			return err
+		}
+		if who.Account == "" {
+			fmt.Printf("%s has no operator account known\n", node)
+			fmt.Printf("  `node account %s <account>` sets it\n", node)
+			return nil
+		}
+		fmt.Printf("%s logs a person in as %s (home %s)\n", node, who.Account, who.Home())
+		return nil
+	}
+	home := ""
+	if len(positionals) == 3 {
+		home = positionals[2]
+	}
+	if err := inv.SetAccount(ctx, node, positionals[1], home); err != nil {
+		return err
+	}
+	fmt.Printf("%s logs a person in as %s\n", node, positionals[1])
+	fmt.Printf("  run `push %s` once ssh-client is assigned, to send its operator config\n", node)
+	return nil
+}
+
 const publicDomainUsage = "node public-domain <name> — what it is now; " +
 	"<name> <domain> to set it; <name> --clear to take it away"

@@ -219,15 +269,6 @@ func tokenCommand(ctx context.Context, args []string) error {
 	// chicken-and-egg entirely: the mesh runs the broker, so a joining node's credentials can
 	// exist before it does. The one-time secret IS the password, so a node's first connection is
 	// already authenticated and enrolment is what happens over it.
-	if management, err := broker.ManagementFromEnvironment(); err == nil {
-		if err := management.CreateNodeAccount(ctx, issued.Node.Name, issued.Secret); err != nil {
-			return err
-		}
-		fmt.Printf("broker account %s created, scoped to %s and the %s exchange\n\n",
-			issued.Node.Name, link.QueueFor(issued.Node.Name), link.Exchange)
-	} else if !errors.Is(err, broker.ErrNotConfigured) {
-		return err
-	}

 	made := token.Token{Node: issued.Node.Name, Signer: key.Public, Secret: issued.Secret,
 		Adopted: issued.Node.Adopted}
@@ -323,8 +364,11 @@ func identityCommand(ctx context.Context, args []string) error {
 }

 func brokerCommand(args []string) error {
+	if len(args) > 0 && args[0] == "certificate" {
+		return busCertificate(args[1:])
+	}
 	if len(args) == 0 || args[0] != "show" {
-		return errors.New("broker show")
+		return errors.New("broker show | broker certificate [--check] --into <directory>")
 	}
 	known, err := broker.FromEnvironment()
 	if errors.Is(err, broker.ErrNotConfigured) {
@@ -2,12 +2,15 @@ package main

 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"flag"
 	"fmt"
 	"os"
 	"strings"

+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/inventory"
 	"github.com/novox/mesh-controller/internal/secrets"
 )

@@ -26,9 +29,25 @@ import (
 //	operator key make [--out <file>]    make a keypair: private half to the file, public half printed
 //	operator key set <public>           tell the mesh which key to seal to
 //	operator key show                   the public key, its fingerprint, and what it can recover
-const operatorUsage = "operator key make [--out <file>] | operator key set <public> [--replace] | operator key show"
+const operatorUsage = "operator key make [--out <file>] | operator key set <public> [--replace] | " +
+	"operator key show | operator issue <name> --invokes <tool,tool|*> | operator revoke <name> | " +
+	"operator list"

 func operatorCommand(ctx context.Context, args []string) error {
+	if len(args) == 0 {
+		return errors.New(operatorUsage)
+	}
+	// The people who may reach the mesh's tools (design 25 §7). Beside the operator's key because
+	// both answer "who, other than a machine, may do something here" — and a person reading this
+	// command's usage is asking exactly that.
+	switch args[0] {
+	case "issue":
+		return personIssue(ctx, args[1:])
+	case "revoke":
+		return personRevoke(ctx, args[1:])
+	case "list":
+		return personList(ctx)
+	}
 	if len(args) < 2 || args[0] != "key" {
 		return errors.New(operatorUsage)
 	}
@@ -160,3 +179,129 @@ func readPrivateKey(path string) (string, error) {
 	}
 	return strings.TrimSpace(string(raw)), nil
 }
+
+// personIssue gives somebody a credential for the mesh's tools, and prints it once.
+//
+// **Printed, not stored.** The mesh keeps a hash and nothing else, so this is the only moment the
+// credential exists anywhere but on the workstation that will use it — the same contract a token has,
+// and for the same reason: a credential recoverable from the mesh's store has the store's blast
+// radius.
+func personIssue(ctx context.Context, args []string) error {
+	set := flag.NewFlagSet("operator issue", flag.ContinueOnError)
+	invokes := set.String("invokes", "", "the tools this person may call, comma-separated, or * for every one")
+	// Flags on either side of the name, because the usage this command prints puts them after it —
+	// and the standard parser stops at the first thing that is not a flag, so the order the command
+	// documents was the one order it refused (2026-09-28).
+	positionals, err := parseAround(set, args)
+	if err != nil {
+		return err
+	}
+	if len(positionals) != 1 {
+		return errors.New("operator issue <name> --invokes <tool,tool|*>")
+	}
+	name := positionals[0]
+	if *invokes == "" {
+		return errors.New(
+			"say what this person may call: --invokes mesh-catalog.catalog_tools,gitea.repo_create, " +
+				"or --invokes '*' for an administrator")
+	}
+	var tools []string
+	for _, t := range strings.Split(*invokes, ",") {
+		if t = strings.TrimSpace(t); t != "" {
+			tools = append(tools, t)
+		}
+	}
+
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+	inv := open.inventory
+
+	if err := inv.RecordPerson(ctx, inventory.Person{Name: name, Invokes: tools}); err != nil {
+		return err
+	}
+	// Refused here rather than at the next composition, where it would stop the whole file being
+	// written for everybody. A name that cannot be part of a subject is one the server would read as
+	// a wider permission than anybody granted.
+	if _, err := broker.PermissionsFor(broker.Principal{
+		Kind: broker.KindPerson, Module: name, Invokes: tools, PasswordHash: "x",
+	}); err != nil {
+		return err
+	}
+
+	user := broker.Principal{Kind: broker.KindPerson, Module: name}.Username()
+	password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: user, Kind: inventory.BusPerson})
+	if err != nil {
+		return err
+	}
+
+	where, err := broker.FromEnvironment()
+	if err != nil && !errors.Is(err, broker.ErrNotConfigured) {
+		return err
+	}
+	held, err := json.Marshal(struct {
+		URL         string   `json:"url"`
+		Fingerprint string   `json:"fingerprint,omitempty"`
+		User        string   `json:"user"`
+		Password    string   `json:"password"`
+		Person      string   `json:"person"`
+		Invokes     []string `json:"invokes"`
+	}{
+		URL: "nats://" + where.Address, Fingerprint: where.Fingerprint,
+		User: user, Password: password, Person: name, Invokes: tools,
+	})
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("issued %s, who may call %s\n", name, strings.Join(tools, ", "))
+	fmt.Println("  this is the only time the credential is printed; the mesh keeps a hash")
+	fmt.Println("  it works once the bus has been told, which is the next push to the machine holding mesh-broker")
+	fmt.Println()
+	fmt.Println(string(held))
+	return nil
+}
+
+func personRevoke(ctx context.Context, args []string) error {
+	if len(args) != 1 {
+		return errors.New("operator revoke <name>")
+	}
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+
+	if err := open.inventory.ForgetPerson(ctx, args[0]); err != nil {
+		return err
+	}
+	// **Revoked at the next composition, not now.** The bus's users are a file, so a credential stops
+	// working when the file no longer names it. Said plainly, because "revoked" that still works for
+	// another minute is worth knowing about.
+	fmt.Printf("%s is forgotten, and their credential stops working at the next composition — "+
+		"push the machine holding mesh-broker to make it so\n", args[0])
+	return nil
+}
+
+func personList(ctx context.Context) error {
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+
+	people, err := open.inventory.People(ctx)
+	if err != nil {
+		return err
+	}
+	if len(people) == 0 {
+		fmt.Println("nobody but machines reaches this mesh")
+		return nil
+	}
+	for _, p := range people {
+		fmt.Printf("%-20s %s\n", p.Name, strings.Join(p.Invokes, ", "))
+	}
+	return nil
+}
@@ -0,0 +1,212 @@
+package main
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/inventory"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// entry is a module as the catalogue holds it: built, so its manifest carries no `build` any more.
+func entry(module string, _ ...string) inventory.Entry {
+	return inventory.Entry{Manifest: catalogue.Manifest{Module: module}}
+}
+
+// stoodOn is what each module's newest build recorded it was handed.
+func stoodOn(edges map[string][]string) map[string][]string {
+	out := map[string][]string{}
+	for module, bases := range edges {
+		for _, b := range bases {
+			out[module] = append(out[module], catalogue.ArtifactStoreScheme+b+"/runtime@sha256:"+strings.Repeat("0", 64))
+		}
+	}
+	return out
+}
+
+// A module built before the module it stands on is built against the old one and reports success
+// (novox/hq 04-ISSUES/131). So bases come first, however the set arrived.
+func TestBasesAreBuiltBeforeWhatStandsOnThem(t *testing.T) {
+	in := []inventory.Entry{entry("app"), entry("runtime"), entry("other"), entry("base")}
+	edges := stoodOn(map[string][]string{"app": {"runtime"}, "runtime": {"base"}})
+	got := orderByBases(in, edges)
+	pos := map[string]int{}
+	for i, e := range got {
+		pos[e.Manifest.Module] = i
+	}
+	if !(pos["base"] < pos["runtime"] && pos["runtime"] < pos["app"]) {
+		t.Fatalf("bases not first: %v", pos)
+	}
+	if len(got) != 4 {
+		t.Fatalf("an entry was lost or doubled: %d", len(got))
+	}
+	// A base outside the set is not waited for: it is not being rebuilt.
+	got = orderByBases([]inventory.Entry{entry("app")}, stoodOn(map[string][]string{"app": {"elsewhere"}}))
+	if len(got) != 1 {
+		t.Fatalf("a dependency outside the set changed the set: %v", got)
+	}
+}
+
+// A module registered from its manifest and never built still names its bases there; once built,
+// the recorded edge is what says so. Both are read, and a module never stands on itself.
+func TestWhatStandsOnAModuleIsReadFromItsBuildOrItsManifest(t *testing.T) {
+	built := entry("gitea")
+	edges := stoodOn(map[string][]string{"gitea": {"mesh-tools"}})
+	if !standsOnModule(built, "mesh-tools", edges) {
+		t.Fatal("a recorded edge was not read")
+	}
+	if standsOnModule(built, "gitea", edges) || standsOnModule(built, "postgres", edges) {
+		t.Fatal("an edge was invented")
+	}
+	fresh := inventory.Entry{Manifest: catalogue.Manifest{Module: "plex", Build: &catalogue.Build{
+		On: []catalogue.BuildsOn{{Arg: "RUNTIME_BASE", Module: "mesh-tools", Artifact: "runtime"}},
+	}}}
+	if !standsOnModule(fresh, "mesh-tools", nil) {
+		t.Fatal("a manifest's own base was not read")
+	}
+}
+
+// A merge names a repository the way the forge does; a source is recorded the way a build was
+// asked for. The two meet on owner/repo and branch, whichever form the record took.
+func TestAMergeMatchesTheSourcesBuiltFromIt(t *testing.T) {
+	m := link.SourceMoved{Owner: "novox", Repo: "mesh-controller", Base: "main",
+		CloneURL: "http://forge.internal:20000/novox/mesh-controller.git"}
+	for _, s := range []inventory.Source{
+		{Repository: "http://forge.internal:20000/novox/mesh-controller.git", Ref: "main"},
+		{Repository: "novox/mesh-controller", Seat: "git", Ref: ""},
+		{Repository: "https://elsewhere.example/novox/mesh-controller", Ref: "main"},
+	} {
+		if !sourceIs(s, m) {
+			t.Errorf("%+v was not matched by the merge", s)
+		}
+	}
+	for _, s := range []inventory.Source{
+		{Repository: "novox/mesh-host", Seat: "git"},
+		{Repository: "http://forge.internal:20000/novox/mesh-controller.git", Ref: "release"},
+	} {
+		if sourceIs(s, m) {
+			t.Errorf("%+v was matched by a merge that is not its", s)
+		}
+	}
+}
+
+// A merge made before the source was last seen is history: it does not move the source, and a
+// merge that says nothing about when it was made is taken as news.
+func TestAMergeOlderThanTheLastLookIsHistory(t *testing.T) {
+	seen := time.Date(2026, 9, 28, 3, 0, 0, 0, time.UTC)
+	if !isHistory("2026-09-28T02:00:00Z", seen) {
+		t.Fatal("an older merge was taken as news")
+	}
+	if isHistory("2026-09-28T04:00:00Z", seen) {
+		t.Fatal("a newer merge was taken as history")
+	}
+	if isHistory("", seen) || isHistory("2026-09-28T02:00:00Z", time.Time{}) {
+		t.Fatal("a merge or a source with no time on it was refused")
+	}
+}
+
+// A module as the catalogue holds it: built from a repository, at a directory inside it.
+func fromRepo(module, repository, path string) inventory.Entry {
+	return inventory.Entry{
+		Manifest: catalogue.Manifest{Module: module},
+		Source:   inventory.Source{Repository: repository, Path: path, Ref: "main"},
+	}
+}
+
+// A merge rebuilds the modules whose own directories it changed, and everything when what it changed
+// is shared. One repository holding many modules is the ordinary case here, and rebuilding all of
+// them for a change to one is what exhausted a registry's pull limit the first night this ran.
+func TestAMergeRebuildsTheModulesItChanged(t *testing.T) {
+	const repo = "http://forge.internal:20000/novox/mesh-catalog.git"
+	gitea := fromRepo("gitea", repo, "modules/gitea")
+	keycloak := fromRepo("keycloak", repo, "modules/keycloak")
+	known := []inventory.Entry{gitea, keycloak, fromRepo("plex", repo, "modules/plex")}
+	candidates := []inventory.Entry{gitea, keycloak}
+	merge := func(paths []string, truncated bool) link.SourceMoved {
+		return link.SourceMoved{Owner: "novox", Repo: "mesh-catalog", Base: "main",
+			Paths: paths, PathsTruncated: truncated}
+	}
+	named := func(entries []inventory.Entry) string {
+		var names []string
+		for _, e := range entries {
+			names = append(names, e.Manifest.Module)
+		}
+		return strings.Join(names, ",")
+	}
+	for _, c := range []struct {
+		what string
+		m    link.SourceMoved
+		want string
+	}{
+		{"one module's own files", merge([]string{"modules/gitea/index.ts", "modules/gitea/client.ts"}, false), "gitea"},
+		{"two modules' files", merge([]string{"modules/gitea/index.ts", "modules/keycloak/module.json"}, false), "gitea,keycloak"},
+		{"a file they share", merge([]string{"tsconfig.json"}, false), "gitea,keycloak"},
+		{"a module the mesh does not hold", merge([]string{"modules/plex/index.ts"}, false), ""},
+		{"nothing said about the files", merge(nil, false), "gitea,keycloak"},
+		{"more files than were listed", merge([]string{"modules/gitea/index.ts"}, true), "gitea,keycloak"},
+	} {
+		if got := named(whatTheMergeTouched(candidates, known, c.m)); got != c.want {
+			t.Errorf("%s: rebuilt %q, wanted %q", c.what, got, c.want)
+		}
+	}
+}
+
+// A module whose recipe packages source from another repository is affected when that repository
+// moves — the manifest the mesh keeps says nothing about it, so the record of what the build read is
+// the only thing that can say so.
+func TestAModuleIsAffectedByTheRepositoryItPackages(t *testing.T) {
+	m := link.SourceMoved{Owner: "novox", Repo: "mesh-controller", Base: "main",
+		CloneURL: "http://forge.internal:20000/novox/mesh-controller.git"}
+	for _, read := range [][]inventory.ReadRepository{
+		{{Repository: "http://forge.internal:20000/novox/mesh-controller.git", Ref: "main"}},
+		{{Repository: "novox/mesh-controller"}},
+		{{Repository: "https://elsewhere.example/novox/other"}, {Repository: "novox/mesh-controller.git", Ref: "main"}},
+	} {
+		if !readsFrom(read, m) {
+			t.Errorf("%+v was not matched by the merge", read)
+		}
+	}
+	for _, read := range [][]inventory.ReadRepository{
+		nil,
+		{{Repository: "novox/mesh-host", Ref: "main"}},
+		{{Repository: "novox/mesh-controller", Ref: "release"}},
+	} {
+		if readsFrom(read, m) {
+			t.Errorf("%+v was matched by a merge that is not its", read)
+		}
+	}
+}
+
+// What a module handed over by hand records about where it came from, and what is refused.
+func TestWhatAHandedOverModuleRecordsAboutItsSource(t *testing.T) {
+	// The whole location: a repository on the mesh's own forge, the directory inside it, the branch
+	// and the commit the manifest was read at.
+	from, err := whereItComesFrom("novox/mesh-catalog", "main", "c0ffee", "modules/gitea", true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if from.Path != "modules/gitea" || from.Seat != "git" || from.Repository != "novox/mesh-catalog" {
+		t.Fatalf("the source records as %+v", from)
+	}
+	// A manifest with no provenance at all is legitimate: fixing something in a hurry.
+	if from, err := whereItComesFrom("", "", "", "", false); err != nil || from != (inventory.Source{}) {
+		t.Fatalf("a manifest handed over with no provenance was refused: %+v, %v", from, err)
+	}
+	for _, c := range []struct {
+		what                          string
+		repository, ref, commit, path string
+		self                          bool
+	}{
+		{what: "a source with no commit", repository: "novox/mesh-catalog", commit: ""},
+		{what: "a commit with no source", commit: "c0ffee"},
+		{what: "a directory inside nothing", path: "modules/gitea"},
+		{what: "a forge holding nothing", self: true},
+		{what: "an address given as a path on the forge", repository: "http://forge.internal:20000/novox/x.git", commit: "c0ffee", self: true},
+	} {
+		if _, err := whereItComesFrom(c.repository, c.ref, c.commit, c.path, c.self); err == nil {
+			t.Errorf("%s was recorded as a source", c.what)
+		}
+	}
+}
@@ -83,9 +83,17 @@ func planFor(ctx context.Context, open *stores, nodeName string) (catalogue.Reso
 		return catalogue.Resolution{}, nil, err
 	}

+	// The operator account this node logs a person in as, and where its home is (novox/hq to-be
+	// 29) — carried so a home-scoped file's owner and path resolve for this machine.
+	who, err := inv.NodeByName(ctx, nodeName)
+	if err != nil {
+		return catalogue.Resolution{}, nil, err
+	}
+
 	resolved, err := catalogue.Resolve(shelf, assigned,
 		catalogue.Node{Name: nodeName, Site: site, Capabilities: capabilities,
-			At: onNetwork[nodeName], PublicDomain: publicDomain}, world)
+			At: onNetwork[nodeName], PublicDomain: publicDomain,
+			Account: who.Account, AccountHome: who.AccountHome}, world)
 	if err != nil {
 		return catalogue.Resolution{}, nil, err
 	}
@@ -177,6 +185,15 @@ func theRestOfTheMesh(ctx context.Context, inv *inventory.Inventory,

 	// Every node, not only the placed ones. A machine that was never put on the private network
 	// still runs modules, still holds claims, and still offers whatever it offers.
+	// **Who holds each seat on record, before anything is resolved** (novox/hq ADR 0131). Both
+	// passes below need it: without it, the assignment standing beside a seat's holder — the next
+	// holder, waiting for the handover — is refused as a second holder, and its node's whole set
+	// with it.
+	holdings, err := inv.Holdings(ctx)
+	if err != nil {
+		return catalogue.World{}, err
+	}
+
 	nodes, err := inv.Nodes(ctx)
 	if err != nil {
 		return catalogue.World{}, err
@@ -219,7 +236,7 @@ func theRestOfTheMesh(ctx context.Context, inv *inventory.Inventory,
 	offered := map[string][]catalogue.Provider{}
 	var firstHeld []catalogue.Held
 	for _, o := range others {
-		got, err := catalogue.Resolve(shelf, o.assigned, o.node, catalogue.World{Unchecked: true})
+		got, err := catalogue.Resolve(shelf, o.assigned, o.node, catalogue.World{Unchecked: true, Holdings: holdings})
 		if err != nil {
 			// Their set does not resolve for some other reason. Not this node's problem to
 			// report, and nothing of theirs is running, so it offers nothing.
@@ -250,7 +267,7 @@ func theRestOfTheMesh(ctx context.Context, inv *inventory.Inventory,
 	// with several providers (novox/hq ADR 0110), so a node consuming one resolves only once the
 	// holder is known. Without them its set is refused here, and a refused node's own claims drop
 	// out of what the mesh holds — so a second holder of one of its seats would pass unrefused.
-	world := catalogue.World{Offered: offered, Held: firstHeld}
+	world := catalogue.World{Offered: offered, Held: firstHeld, Holdings: holdings}
 	var held []catalogue.Held
 	for _, o := range others {
 		got, err := catalogue.Resolve(shelf, o.assigned, o.node, world)
@@ -488,6 +505,13 @@ func renderingFor(ctx context.Context, open *stores, node string,
 	if err != nil {
 		return catalogue.Rendering{}, inventory.Node{}, err
 	}
+	// The private network's range, offered to a module as ${machine:mesh-range} — a module that must
+	// name the whole mesh (an intrusion filter that must never ban a tunnel peer) names it here
+	// rather than hardcoding a value it cannot know.
+	meshRange, err := overlayRange(ctx, inv)
+	if err != nil {
+		return catalogue.Rendering{}, inventory.Node{}, err
+	}

 	// The artifact store as this node reaches it now — the address every image and archive the
 	// mesh built is fetched through, composed here and recorded nowhere — with what the mesh has
@@ -513,6 +537,19 @@ func renderingFor(ctx context.Context, open *stores, node string,
 		return catalogue.Rendering{}, inventory.Node{}, err
 	}

+	// Each machine's operator account, so an ssh Host block can name the login for every node
+	// (novox/hq to-be 29). Keyed by the bare node name, which entriesFrom falls back to.
+	allNodes, err := inv.Nodes(ctx)
+	if err != nil {
+		return catalogue.Rendering{}, inventory.Node{}, err
+	}
+	accounts := map[string]string{}
+	for _, n := range allNodes {
+		if n.Account != "" {
+			accounts[n.Name] = n.Account
+		}
+	}
+
 	// And every routed name → the node that serves it (novox/hq ADR 0066). Alongside the
 	// `<node>.internal` names above, so a container — or an internal ACME validator — resolves a
 	// routed name to the proxy that serves it, mesh-wide. The mesh publishes the names it was told
@@ -593,12 +630,31 @@ func renderingFor(ctx context.Context, open *stores, node string,
 	if err != nil {
 		return catalogue.Rendering{}, inventory.Node{}, err
 	}
+	// The bus's user list, for the machine that runs the bus. Composed per push rather than kept,
+	// because it is a function of the mesh's records and a kept copy could disagree with them.
+	busUsers, err := composeBusUsers(ctx, inv, plan.Modules)
+	if err != nil {
+		return catalogue.Rendering{}, inventory.Node{}, err
+	}
+	memberships, err := inv.BusMemberships(ctx)
+	if err != nil {
+		return catalogue.Rendering{}, inventory.Node{}, err
+	}
+	// Which of this machine's links face outside, which is what the derived filter is written
+	// around (novox/hq ADR 0140). Reported by the machine, never set.
+	outwardLinks, err := inv.OutwardLinksOf(ctx, node)
+	if err != nil {
+		return catalogue.Rendering{}, inventory.Node{}, err
+	}
 	return catalogue.Rendering{
-		Settings: settings, Generators: gens, Grants: grants, Needed: needed, Ports: ports,
+		BusMembership: memberships[node],
+		Settings:      settings, Generators: gens, Grants: grants, Needed: needed, Ports: ports,
 		Certificate: certificate, Authority: authority, Mesh: private, Names: names,
 		Machines: machines,
-		Suffix:   overlay.Suffix(), Foundation: foundation, Kept: kept, Adopted: record.Adopted,
+		Suffix:   overlay.Suffix(), MeshRange: meshRange, TunnelInterface: overlay.Interface, Accounts: accounts, Foundation: foundation,
+		Kept: kept, Adopted: record.Adopted, OutwardLinks: outwardLinks,
 		Given: given, Taken: taken, Seats: seats, ArtifactStore: artifactStore, Built: built,
+		BusUsers: busUsers,
 	}, record, nil
 }

@@ -923,12 +979,26 @@ func planCommand(ctx context.Context, args []string) error {
 			if !ok {
 				continue
 			}
-			fmt.Printf("\n--- %v  %v ---\n%s", r["id"], r["path"], content)
+			fmt.Printf("\n--- %s ---\n%s", shownAs(r), content)
 		}
 	}
 	return nil
 }

+// shownAs is the heading `plan --show` puts over a resource's content.
+//
+// **A file written into says so.** Its content is the mesh's part of a file that is otherwise the
+// machine's — the keys of a JSON document (novox/hq ADR 0102), the region of a hosts file (issue
+// 128). Shown under a bare path it reads as the whole file, and a person checking what a take
+// replaces would see a hosts file of a dozen lines where the machine keeps thirty.
+func shownAs(r map[string]any) string {
+	heading := fmt.Sprintf("%v  %v", r["id"], r["path"])
+	if into, ok := r["into"].(string); ok && into != "" {
+		heading += fmt.Sprintf(" (written into, %s)", into)
+	}
+	return heading
+}
+
 // licencesFor is what this node can be answered with by record, and what it was put on.
 //
 // A mesh with no licences at all is the ordinary case and must not be an error: every existing
@@ -1144,6 +1214,76 @@ func portsOn(
 	return out, nil
 }

+// composeBusUsers is the bus's user list, for a push to the machine that runs the bus.
+//
+// Empty for every other machine, and for every machine while the mesh is on the bus it runs on
+// today — where accounts are a management call and there is no file to write.
+//
+// **Composed on each push, never kept.** The list is a function of the mesh's records (who exists,
+// what runs where, what each declares), and a stored copy would be a second account of who may reach
+// the bus, able to disagree with the records while both looked internally consistent (ADR 0043).
+//
+// A user the mesh has never minted a password for is **left out and said**, not written as a user
+// without one — the composer refuses that, because a user with no password is a user anybody is. That
+// is an ordinary situation with an obvious remedy (`module issue`, or enrolling), so the push carries
+// the rest rather than failing: a bus that is missing one module's user is a mesh where that module
+// cannot connect, and a bus with no file at all is a mesh where nothing can.
+func composeBusUsers(ctx context.Context, inv *inventory.Inventory,
+	onThisNode []catalogue.Manifest) (string, error) {
+
+	// **Not gated on which bus the controller is on, and that was a bug.** It read "compose this only
+	// once the mesh is on the new bus" — which cannot work, because the server needs its user list
+	// *before* anything moves onto it. Step 2 of the change is exactly that: the server stands in the
+	// mesh carrying nothing, on its own ports, while every node is still on the old bus (novox/hq
+	// ADR 0116). Under the old gating that step could not happen: the module would come up, find no
+	// accounts file, and its entrypoint would wait for one the controller had decided not to write.
+	//
+	// So the question is only whether this machine runs the module that asked for the file. A mesh
+	// that never moves has written a user list nothing reads, which costs a few hundred bytes on one
+	// node; the reverse cost a step that cannot be taken.
+	//
+	// Asked of what this push resolves to rather than of the seat's holder mesh-wide: the file is a
+	// resource of that module, so the question is whether it is here.
+	holdsTheBus := false
+	for _, m := range onThisNode {
+		if m.BusUsers != "" && m.ClaimsSeat("mesh-broker") {
+			holdsTheBus = true
+		}
+	}
+	if !holdsTheBus {
+		return "", nil
+	}
+
+	records, err := inv.BusRecords(ctx)
+	if err != nil {
+		return "", err
+	}
+	users, err := broker.Users(records)
+	if err != nil {
+		return "", err
+	}
+	kept, err := inv.BusUsers(ctx)
+	if err != nil {
+		return "", err
+	}
+	hashes := make(map[string]string, len(kept))
+	for name, u := range kept {
+		hashes[name] = u.PasswordHash
+	}
+	filled, missing := broker.WithPasswords(users, hashes)
+	if len(missing) > 0 {
+		fmt.Printf("the bus's user list leaves out %d user(s) the mesh has minted no credential "+
+			"for: %s. Each is a user that cannot connect until one is issued\n",
+			len(missing), strings.Join(missing, ", "))
+	}
+	if len(filled) == 0 {
+		return "", fmt.Errorf(
+			"this machine runs the bus and not one user has a credential, so the composed list " +
+				"would refuse every connection in the mesh")
+	}
+	return broker.ComposeAccounts(filled)
+}
+
 // foundationPortsFor is the broker port, kept only when a module resolved onto this node listens
 // on it (novox/hq issue: the broker opening leaked onto every node). The foundation opening
 // exists to WIDEN the broker's `from: mesh` port to from-anywhere, because a machine enrolling is
@@ -35,3 +35,17 @@ func TestListensLinesAreEmptyForAModuleWithNothingToListenOn(t *testing.T) {
 		t.Errorf("a module with no listens should print nothing, got %v", got)
 	}
 }
+
+// `plan --show` says when a file is written into rather than over (novox/hq issue 128), or the
+// mesh's region of a hosts file reads as the whole file.
+func TestAFileWrittenIntoIsShownAsSuch(t *testing.T) {
+	region := shownAs(map[string]any{
+		"id": "mesh-wireguard.fact-node-names", "path": "/etc/hosts", "into": "block"})
+	if region != "mesh-wireguard.fact-node-names  /etc/hosts (written into, block)" {
+		t.Errorf("the region is shown as %q", region)
+	}
+	whole := shownAs(map[string]any{"id": "dnsmasq.fact-node-zones", "path": "/etc/mesh-resolver/nodes.conf"})
+	if strings.Contains(whole, "written into") {
+		t.Errorf("a whole file is shown as written into: %q", whole)
+	}
+}
@@ -38,6 +38,27 @@ func reportUnhostable(node string, plan catalogue.Resolution) {
 // nothing in it was wrong, and no one edit was the one that should have been a new file.

 // serve is the control plane running: one connection to the broker, one queue, one consumer.
+// connectLink opens the controller's link over whichever bus this process is on (design 25: one
+// variable moves it). The streams and this controller's consumers are raised first on the new bus,
+// so nothing served here finds them missing.
+func connectLink(ctx context.Context, inv *inventory.Inventory, enroller link.Enroller, listener link.Listener) (*link.Server, error) {
+	busAddress, err := broker.BusAddress()
+	if err != nil {
+		return nil, err
+	}
+	if inv != nil {
+		if err := raiseTheBus(ctx, inv, busAddress); err != nil {
+			return nil, err
+		}
+	}
+	js, err := broker.Dial(busAddress)
+	if err != nil {
+		return nil, fmt.Errorf("the mesh is on the bus at %s and this control plane cannot reach it: %w",
+			broker.BareAddress(busAddress), err)
+	}
+	return link.ConnectNats(js, enroller, listener), nil
+}
+
 func serve(ctx context.Context) error {
 	open, err := openStores(ctx)
 	if err != nil {
@@ -61,11 +82,6 @@ func serve(ctx context.Context) error {
 	}
 	fmt.Printf("signing as %s\n", key.Fingerprint()[:16])

-	management, err := broker.ManagementFromEnvironment()
-	if err != nil && !errors.Is(err, broker.ErrNotConfigured) {
-		return err
-	}
-
 	// Where the broker is and what to expect there, so a node can be told how to come back
 	// without a person and a new token.
 	known, err := broker.FromEnvironment()
@@ -77,12 +93,22 @@ func serve(ctx context.Context) error {
 			"reconnect. Set %s and %s.\n", broker.AddressVar, broker.CertificateVar)
 	}

-	work := link.Enrolment{Inventory: inv, Identity: ident, Management: management, Broker: known}
-	server, err := link.Connect(work, work)
+	// **Which bus this mesh is on, read once** (novox/hq ADR 0116 step 5). Both clients ship; both
+	// being live is refused, because a mesh half on each is one where a declaration goes out on one
+	// and the report comes back on the other, and every component logs success while it happens.
+
+	work := link.Enrolment{Inventory: inv, Identity: ident, Broker: known,
+		OnNATS: true}
+	server, err := connectLink(ctx, inv, work, work)
 	if err != nil {
 		return err
 	}
 	defer server.Close()
+
+	// The bus's own objects, asserted on every start. **Not created once at genesis**: a stream
+	// somebody deleted, a mesh raised from a restored backup, or a bus whose data directory was
+	// replaced all have records and no objects — and a node whose consumer is missing hears nothing
+	// while everything else about it looks correct.
 	// And build results nobody was waiting for. A build triggered any other way than `build`
 	// would otherwise be reported into the void, which is the same as not reporting it.
 	server.Records(builds{inv})
@@ -136,13 +162,19 @@ func declare(ctx context.Context, args []string) error {
 		return err
 	}

-	server, err := link.Connect(nil, nil)
+	// **With the inventory, so the bus is raised** (novox/hq ADR 0134, design 30). A module's
+	// declaration and how it hears what it consumes move together: its consumer is derived from the
+	// same records this declaration is composed from. Raised only when the control plane started
+	// serving, a module that gained a `consumes` was sent a declaration it could act on and a
+	// consumer that never delivered the event — and nothing anywhere said the two disagreed
+	// (found on review, 2026-09-28). Everything the raise does is idempotent.
+	server, err := connectLink(ctx, inv, nil, nil)
 	if err != nil {
 		return err
 	}
 	defer server.Close()

-	if err := link.Declare(ctx, server.Channel(), ident, node, raw, 15*time.Second); err != nil {
+	if err := link.Declare(ctx, server.Bus(), ident, node, raw, 15*time.Second); err != nil {
 		return err
 	}
 	fmt.Printf("sent %s a signed declaration (%d bytes)\n", node, len(raw))
@@ -249,7 +281,7 @@ func pushCommand(ctx context.Context, args []string) error {
 		return err
 	}

-	server, err := link.Connect(nil, nil)
+	server, err := connectLink(ctx, nil, nil, nil)
 	if err != nil {
 		return err
 	}
@@ -310,7 +342,7 @@ func pushCommand(ctx context.Context, args []string) error {
 		if err != nil {
 			return err
 		}
-		if err := link.Declare(ctx, server.Channel(), ident, s.node, body, 15*time.Second); err != nil {
+		if err := link.Declare(ctx, server.Bus(), ident, s.node, body, 15*time.Second); err != nil {
 			return err
 		}
 		// After it is away, not before. A digest recorded for something that failed to send would
@@ -393,7 +425,7 @@ func pushCommand(ctx context.Context, args []string) error {
 					return declarationWith(held, open, node, plan, settings, gens, Allocating)
 				},
 				func(s readyNode, body []byte) error {
-					if err := link.Declare(ctx, server.Channel(), ident, s.node, body,
+					if err := link.Declare(ctx, server.Bus(), ident, s.node, body,
 						15*time.Second); err != nil {
 						return err
 					}
@@ -502,8 +534,14 @@ func composeEach(names []string,
 			continue
 		}
 		if len(declared.Resources) == 0 {
-			fmt.Printf("%s is assigned nothing — skipped\n", name)
-			continue
+			// Sent, not skipped (novox/hq issue 127). A node whose declaration composes to
+			// nothing may have HELD something before — the broker opening a placement gave it,
+			// say — and skipping the empty declaration leaves that last resource in force
+			// forever, re-applied by the node's own heartbeat, with no way for the mesh to say
+			// it is gone. An empty declaration is the correction: the host drops what the mesh
+			// owned and keeps what it found (the adoption envelope still rides along). A node
+			// that never held anything applies it as the no-op it is.
+			fmt.Printf("%s owns nothing now — sent so it drops what it last held\n", name)
 		}
 		sending = append(sending, readyNode{name, declared})
 	}
@@ -600,7 +638,7 @@ func sendTo(ctx context.Context, open *stores, names []string) error {
 			len(refusals), strings.Join(refusals, "\n\n"))
 	}

-	server, err := link.Connect(nil, nil)
+	server, err := connectLink(ctx, nil, nil, nil)
 	if err != nil {
 		return err
 	}
@@ -611,7 +649,7 @@ func sendTo(ctx context.Context, open *stores, names []string) error {
 		if err != nil {
 			return err
 		}
-		if err := link.Declare(ctx, server.Channel(), ident, s.node, body, 15*time.Second); err != nil {
+		if err := link.Declare(ctx, server.Bus(), ident, s.node, body, 15*time.Second); err != nil {
 			return err
 		}
 		record, err := inv.NodeByName(ctx, s.node)
@@ -664,3 +702,122 @@ func wouldSend(ctx context.Context, open *stores,
 	}
 	return out, nil
 }
+
+// raiseTheBus asserts the streams and consumers the mesh's own traffic needs.
+//
+// **Every start, and it says what it did.** The objects are the mesh's, created by nothing else —
+// the controller is their only writer (design 25 §3) — so a mesh that came up without them is one
+// where nodes connect, authenticate, and hear nothing. Said rather than silent for the reason the
+// first line of `serve` is said: a log that is quiet on success and loud on failure reads as broken
+// when it is working.
+func raiseTheBus(ctx context.Context, inv *inventory.Inventory, address string) error {
+	js, err := broker.Dial(address)
+	if err != nil {
+		return fmt.Errorf("the mesh is on the bus at %s and this control plane cannot reach it: %w",
+			broker.BareAddress(address), err)
+	}
+	defer js.Close()
+
+	// **Its own user, before anything else.** The controller's account is created by the installer at
+	// a bootstrap password, before there is a controller to mint one — so nothing recorded a hash for
+	// it, and the first composition would leave the writer out of the file it was writing. Recorded
+	// only if absent: a credential the mesh minted since is the one that counts.
+	// **Its own user, before anything else it does here.** The controller's account is created by the
+	// installer at a bootstrap password, before there is a controller to mint one — so nothing
+	// recorded a hash for it, and the first composition would leave the writer out of the file it was
+	// writing: a bus nothing can connect to, produced by the thing connected to it. Recorded only if
+	// absent, so a restart cannot put the bootstrap credential back over a rotated one.
+	if user, password, _ := broker.CredentialIn(address); user != "" && password != "" {
+		if err := inv.SeedBusUser(ctx, inventory.BusUser{
+			Username: user, Kind: inventory.BusController,
+		}, password); err != nil {
+			return fmt.Errorf("cannot record the credential this control plane is using: %w", err)
+		}
+	}
+
+	nodes, err := inv.Nodes(ctx)
+	if err != nil {
+		return err
+	}
+	names := make([]string, 0, len(nodes))
+	for _, n := range nodes {
+		names = append(names, n.Name)
+	}
+	if err := broker.Raise(js, names); err != nil {
+		return err
+	}
+	// The work queues of the mesh's own roles (novox/hq ADR 0121). The queue before the holder,
+	// deliberately: work queues until somebody arrives to do it, so assigning a build machine a week
+	// after something started asking for builds flushes the backlog instead of having lost it.
+	// With the seats' holders, so each role's work queue gets the consumer its holder takes
+	// work from. Passed as nil until the first live raise, which left the build machine bound to a
+	// consumer nothing had created (2026-09-28).
+	holders, err := seatHolders(ctx, inv)
+	if err != nil {
+		return err
+	}
+	if err := broker.RaiseSeats(js, inventory.MeshSeats(), holders); err != nil {
+		return err
+	}
+	// And how every module hears what it consumes. Derived from the same records the user list is
+	// composed from, so a module the mesh grants a consumer's subjects has that consumer waiting.
+	// Done on every raise, not only when a credential is issued: every module moved onto this bus
+	// by the rollout was issued on the old one, and came up with nothing to bind to (2026-09-28).
+	records, err := inv.BusRecords(ctx)
+	if err != nil {
+		return err
+	}
+	users, err := broker.Users(records)
+	if err != nil {
+		return err
+	}
+	hearing := 0
+	for _, p := range users {
+		consumer, needed := broker.ConsumerFor(p)
+		if !needed {
+			continue
+		}
+		if err := js.EnsureConsumer(consumer); err != nil {
+			return fmt.Errorf("how %s on %s hears what it consumes: %w", p.Module, p.Node, err)
+		}
+		hearing++
+	}
+	fmt.Printf("the bus at %s has its streams, %d machine(s) can hear a declaration, and %d module(s) "+
+		"can hear what they consume\n", broker.BareAddress(address), len(names), hearing)
+	return nil
+}
+
+// seatHolders is who holds each of the mesh's seats, by seat name: the record where a handover
+// wrote one, and the assigned module claiming the seat otherwise — the same derivation the
+// resolver makes, read from the catalogue rather than re-resolved.
+func seatHolders(ctx context.Context, inv *inventory.Inventory) (map[string]broker.Holder, error) {
+	out := map[string]broker.Holder{}
+	entries, err := inv.Catalogued(ctx)
+	if err != nil {
+		return nil, err
+	}
+	for _, e := range entries {
+		if len(e.On) == 0 {
+			continue
+		}
+		for _, c := range e.Manifest.Claims {
+			seat, known := catalogue.SeatNamed(c.Name)
+			if !known {
+				continue
+			}
+			if _, taken := out[seat.Name]; !taken {
+				out[seat.Name] = broker.Holder{Node: e.On[0], Module: e.Manifest.Module}
+			}
+		}
+	}
+	recorded, err := inv.Holdings(ctx)
+	if err != nil {
+		return nil, err
+	}
+	for _, h := range recorded {
+		if seat, known := catalogue.SeatNamed(h.Claim); known {
+			out[seat.Name] = broker.Holder{Node: h.Node, Module: h.Module}
+		}
+	}
+	return out, nil
+}
@@ -39,12 +39,14 @@ func TestOneUnresolvableNodeStillLetsTheRestBeSent(t *testing.T) {
 	}
 }

-// And a machine assigned nothing is neither sent nor a refusal — it is nothing to say.
-func TestAMachineAssignedNothingIsNotARefusal(t *testing.T) {
+// A machine whose declaration composes to nothing is SENT the empty declaration, not skipped
+// (novox/hq issue 127): it may have held something before, and only sending the empty
+// declaration tells it to drop what the mesh owned. It is never a refusal.
+func TestAnEmptyDeclarationIsSentSoTheNodeDropsWhatItHeld(t *testing.T) {
 	sending, refusals := composeEach([]string{"spare"},
 		func(string) (sendable, error) { return sendable{}, nil })
-	if len(sending) != 0 || len(refusals) != 0 {
-		t.Errorf("a machine assigned nothing was treated as something: %v / %v", sending, refusals)
+	if len(sending) != 1 || len(refusals) != 0 {
+		t.Errorf("an empty declaration must be sent, not skipped or refused: %v / %v", sending, refusals)
 	}
 }

@@ -0,0 +1,455 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/nats-io/nats.go"
+
+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/inventory"
+	"github.com/novox/mesh-controller/internal/secrets"
+)
+
+// Moving the mesh's own traffic to the bus being built (novox/hq ADR 0116 step 5).
+//
+// **The whole mesh moves at once, so there is nothing to inspect afterwards.** Every seam ships both
+// transports and every one of them chooses by a single fact; this is the step that flips it. That
+// shape is deliberate — steps 1 to 4 leave every node where it is, so the cost of being wrong stays
+// bounded until here — and it means the useful work is almost all in the checking.
+//
+// So `rollout check` is the command that matters and the one that can be run any number of times
+// against a mesh that is serving. It answers from records: what is missing, and what would happen.
+// `rollout` itself refuses unless the check is clean.
+//
+// **The old broker goes with the move, and goes last** (novox/hq ADR 0131): AMQP is not a provision,
+// so once every machine reports on the new bus its module is unassigned. Only the mesh's own traffic
+// is what moves, which is why this is survivable at all: what breaks if it goes wrong is the mesh's
+// ability to change things, not the services its modules are serving — measured on 2026-09-27, when
+// a seat emptied mid-change and the control plane looped for two hours while every service stayed up.
+
+const rolloutUsage = "rollout check | rollout mint [--again] | rollout hand <node> | rollout --confirm"
+
+func rolloutCommand(ctx context.Context, args []string) error {
+	switch {
+	case len(args) == 1 && args[0] == "check":
+		return rolloutCheck(ctx)
+	case len(args) == 1 && args[0] == "mint":
+		return rolloutMint(ctx, false)
+	case len(args) == 2 && args[0] == "hand":
+		return rolloutHand(ctx, args[1])
+	case len(args) == 2 && args[0] == "mint" && args[1] == "--again":
+		// Every credential minted afresh, whether or not one exists — for a mint that was wrong
+		// before anything was pushed. Afterwards nothing that received the old one still works,
+		// which is fine exactly when nothing received it.
+		return rolloutMint(ctx, true)
+	case len(args) == 1 && args[0] == "--confirm":
+		return errors.New(
+			"the rollout itself is not built yet: `rollout check` answers whether it could run, and " +
+				"what is missing. Moving every node at once is the one step with nothing to inspect " +
+				"afterwards, so it is not being written before the check it depends on has been run " +
+				"against a real mesh")
+	default:
+		return errors.New(rolloutUsage)
+	}
+}
+
+// rolloutCheck says whether the mesh could move, and what would happen if it did.
+func rolloutCheck(ctx context.Context) error {
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+	inv := open.inventory
+
+	state, err := readinessOf(ctx, inv)
+	if err != nil {
+		return err
+	}
+
+	fmt.Println("the bus this mesh would move to")
+	if state.TheBus == "" {
+		fmt.Printf("  nothing names one (%s is unset)\n", broker.NATSVar)
+	} else {
+		standing := "not answering"
+		if state.ServerStanding {
+			standing = "answering"
+		}
+		fmt.Printf("  %s — %s\n", state.TheBus, standing)
+	}
+	fmt.Println()
+
+	fmt.Println("what would move")
+	for _, step := range broker.WhatMoves(state) {
+		fmt.Printf("  %s\n", step)
+	}
+	fmt.Println()
+
+	why := notReadyOf(state)
+	if len(why) == 0 {
+		fmt.Println("nothing is missing: this mesh could move its bus.")
+		fmt.Println()
+		fmt.Println("Read `what would move` above once more before running it. Every node moves at the")
+		fmt.Println("same moment and there is no half-moved state to look at afterwards.")
+		return nil
+	}
+	fmt.Printf("not ready — %d thing(s) to do first:\n", len(why))
+	for i, w := range why {
+		fmt.Printf("  %d. %s\n", i+1, w)
+	}
+	return nil
+}
+
+// readinessOf gathers what the mesh knows about its own ability to move.
+//
+// Reads and one dial, and nothing is written. Safe to run on a mesh that is serving, which is the
+// point: the answer is only useful if it can be had without committing to anything.
+func readinessOf(ctx context.Context, inv *inventory.Inventory) (broker.Readiness, error) {
+	state := broker.Readiness{
+		Credentialled:       map[string]bool{},
+		ModuleCredentialled: map[string]bool{},
+		// The old broker keeps its other clients on this installation, and saying so is how the plan
+		// stops reading as a retirement.
+	}
+
+	address, _, err := broker.OnNATS()
+	if err != nil {
+		return state, err
+	}
+	state.TheBus = address
+	if address != "" {
+		// One dial, briefly. "Is it answering" is the one fact records cannot hold, and a mesh about
+		// to move onto a server that is not there should hear it here rather than afterwards.
+		//
+		// **Dialled the way the mesh dials it** — credential and pin — because a bare connect to a
+		// bus that requires TLS and a user fails at the handshake, and the check then reported a
+		// standing server as absent (seen live, 2026-09-28).
+		if js, err := broker.Dial(address, nats.Timeout(5*time.Second)); err == nil {
+			state.ServerStanding = true
+			js.Close()
+		}
+	}
+
+	nodes, err := inv.Nodes(ctx)
+	if err != nil {
+		return state, err
+	}
+	kept, err := inv.BusUsers(ctx)
+	if err != nil {
+		return state, err
+	}
+	shelf, err := inv.Catalogue(ctx)
+	if err != nil {
+		return state, err
+	}
+
+	for _, n := range nodes {
+		state.Nodes = append(state.Nodes, n.Name)
+		_, has := kept[broker.Principal{Kind: broker.KindNode, Node: n.Name}.Username()]
+		state.Credentialled[n.Name] = has
+
+		assigned, err := inv.Assigned(ctx, n.Name)
+		if err != nil {
+			return state, err
+		}
+		for _, module := range assigned {
+			m, known := shelf[module]
+			if !known {
+				continue
+			}
+			// The machine that holds the bus seat is the one that would be sent the user list.
+			if m.BusUsers != "" && m.ClaimsSeat("mesh-broker") {
+				state.Holder = n.Name
+				state.AccountsComposed = wasSentTheUserList(ctx, inv, n.Name)
+			}
+			// A module that never speaks needs no credential, so it is not counted as missing one.
+			if !speaksOnTheBus(m) {
+				continue
+			}
+			named := n.Name + "/" + module
+			state.Modules = append(state.Modules, named)
+			_, hasOne := kept[broker.Principal{
+				Kind: broker.KindModule, Node: n.Name, Module: module,
+			}.Username()]
+			state.ModuleCredentialled[named] = hasOne
+		}
+	}
+	return state, nil
+}
+
+// speaksOnTheBus says whether a module reaches the bus at all.
+//
+// A third of the catalogue never does (novox/hq ADR 0120), and counting those as missing a credential
+// would bury the ones that matter under a list nobody can act on.
+func speaksOnTheBus(m catalogue.Manifest) bool {
+	return len(m.Emits) > 0 || len(m.Consumes) > 0 || len(m.Tools) > 0 ||
+		len(m.DefinesSeats) > 0 || len(m.Uses) > 0 || len(m.Claims) > 0
+}
+
+// wasSentTheUserList says whether the machine holding the bus has had a declaration since the user
+// list became part of one.
+//
+// Read from what the mesh recorded sending rather than asked of the machine: a machine that is away
+// has still been sent it, and this question is about whether the mesh did its part.
+func wasSentTheUserList(ctx context.Context, inv *inventory.Inventory, node string) bool {
+	digest, err := inv.Outstanding(ctx, node)
+	return err == nil && strings.TrimSpace(digest) != ""
+}
+
+// notReadyOf is the readiness reasoning, named here so a test can reach it without the command's
+// printing. The reasoning itself is the broker package's, where it is pure.
+func notReadyOf(state broker.Readiness) []string { return broker.NotReady(state) }
+
+// rolloutMint gives every principal the new bus will have a credential it does not yet have, and
+// puts each where its owner reads it (novox/hq design 28, task 5.2): a machine's as a membership
+// sealed into its declaration, a module's as its broker secret, the control plane's own as its
+// `bus` secret. Idempotent: what already has a hash is left alone, so running it again is harmless.
+//
+// **Before anything moves, and it is what makes moving possible.** A machine moved without a
+// credential cannot come back, and afterwards there is no bus to tell it anything over — which is
+// why `rollout check` refuses until this has run. The bus's address is worked out here, from where
+// the module that provides it is assigned, rather than read from this process's environment: this
+// process is still on the old bus when this runs, and must be.
+func rolloutMint(ctx context.Context, again bool) error {
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+	inv := open.inventory
+
+	known, err := broker.FromEnvironment()
+	if err != nil {
+		return fmt.Errorf("the bus's certificate is not known to this process, and every membership "+
+			"must carry its fingerprint: %w", err)
+	}
+	shelf, err := inv.Catalogue(ctx)
+	if err != nil {
+		return err
+	}
+	entries, err := inv.Catalogued(ctx)
+	if err != nil {
+		return err
+	}
+	var busNode, controllerNode string
+	for _, e := range entries {
+		switch {
+		case e.Manifest.ClaimsSeat("mesh-broker") && providesBus(e.Manifest) && len(e.On) > 0:
+			busNode = e.On[0]
+		case e.Manifest.Module == "mesh-controller" && len(e.On) > 0:
+			controllerNode = e.On[0]
+		}
+	}
+	if busNode == "" {
+		return errors.New("no assigned module provides mesh-bus and claims mesh-broker, so there is no " +
+			"bus to mint credentials for — register and assign it first")
+	}
+	onNetwork, err := whereEveryoneIs(ctx, inv, shelf)
+	if err != nil {
+		return err
+	}
+	busHost := onNetwork[busNode]
+	if busHost == "" {
+		// **The hub is not in that map.** The machine that took over the tunnel is where the current
+		// bus already answers, and every machine dials it at the address the mesh handed them — so
+		// when the new bus runs on the same machine, that address is the one to tell them, with the
+		// new port. Found live: the control node is the hub, and the map lists the machines placed
+		// around it.
+		// The host alone: no scheme (BareAddress adds one where none was, which is the wrong
+		// direction here — every URL built below adds its own) and no port.
+		_, _, host := broker.CredentialIn(known.Address)
+		if host == "" {
+			host = known.Address
+		}
+		if _, after, hasScheme := strings.Cut(host, "://"); hasScheme {
+			host = after
+		}
+		host = strings.TrimSpace(host)
+		if i := strings.LastIndex(host, ":"); i > 0 && !strings.Contains(host[i:], "]") {
+			host = host[:i]
+		}
+		if host == "" {
+			return fmt.Errorf("%s runs the new bus and has no address on the private network, and the "+
+				"current bus's address is unknown too, so no machine could be told where it is", busNode)
+		}
+		busHost = host
+	}
+	busAddress := busHost + ":4222"
+
+	records, err := inv.BusRecords(ctx)
+	if err != nil {
+		return err
+	}
+	users, err := broker.Users(records)
+	if err != nil {
+		return err
+	}
+	kept, err := inv.BusUsers(ctx)
+	if err != nil {
+		return err
+	}
+	hashes := make(map[string]string, len(kept))
+	for name, u := range kept {
+		hashes[name] = u.PasswordHash
+	}
+	_, missing := broker.WithPasswords(users, hashes)
+	wanted := map[string]bool{}
+	for _, m := range missing {
+		wanted[m] = true
+	}
+
+	var machines, modules, skipped int
+	for _, p := range users {
+		if !again && !wanted[p.Username()] {
+			continue
+		}
+		switch p.Kind {
+		case broker.KindController:
+			if controllerNode == "" {
+				return errors.New("the control plane is not assigned anywhere, so its credential has nowhere to go")
+			}
+			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: inventory.BusController})
+			if err != nil {
+				return err
+			}
+			url := "nats://" + p.Username() + ":" + password + "@" + busAddress
+			if err := inv.AcceptSecretForModule(ctx, controllerNode, "mesh-controller", "bus", url); err != nil {
+				return fmt.Errorf("the control plane's credential is minted and could not be sealed to %s: %w", controllerNode, err)
+			}
+			fmt.Printf("control plane: credential minted, sealed to %s as its `bus` secret\n", controllerNode)
+
+		case broker.KindNode:
+			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: inventory.BusNode, Node: p.Node})
+			if err != nil {
+				return err
+			}
+			membership, _ := json.Marshal(map[string]string{
+				"broker": busAddress, "fingerprint": known.Fingerprint, "password": password, "transport": "nats",
+			})
+			key, err := inv.SealingKeyOf(ctx, p.Node)
+			if err != nil {
+				return fmt.Errorf("%s has no sealing key, so its membership cannot be sealed to it: %w", p.Node, err)
+			}
+			sealed, err := secrets.Seal(key, membership)
+			if err != nil {
+				return err
+			}
+			if err := inv.PutBusMembership(ctx, p.Node, sealed); err != nil {
+				return err
+			}
+			machines++
+
+		case broker.KindModule:
+			if p.Module == "mesh-controller" {
+				// The control plane is a module too, and its `broker` secret is the old bus's
+				// credential it is still using while this runs. Writing the new bus's blob there
+				// cut the mesh off from its own old bus mid-move (2026-09-28). Its new-bus credential
+				// is the controller principal's `bus` secret above; nothing else is needed here.
+				skipped++
+				continue
+			}
+			m, inShelf := shelf[p.Module]
+			if !inShelf {
+				skipped++
+				continue
+			}
+			if _, reads := m.OwnSecrets["broker"]; !reads {
+				fmt.Printf("  %s on %s speaks on the bus but declares no `broker` secret to receive a credential in; skipped\n", p.Module, p.Node)
+				skipped++
+				continue
+			}
+			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: inventory.BusModule, Node: p.Node, Module: p.Module})
+			if err != nil {
+				return err
+			}
+			if err := issueWith(ctx, inv, m, p.Node, "", known, busAddress, p.Username(), password); err != nil {
+				return err
+			}
+			modules++
+
+		default:
+			skipped++
+		}
+	}
+	fmt.Printf("minted for %d machine(s) and %d module runtime(s); %d skipped; the bus is at %s\n",
+		machines, modules, skipped, busAddress)
+	fmt.Println("  each machine's membership and each module's credential arrive with the next push of its machine;")
+	fmt.Println("  push the machine running the bus first, so the bus stands with its user list before anything dials it")
+	return nil
+}
+
+// providesBus is whether a manifest provides the mesh's bus.
+func providesBus(m catalogue.Manifest) bool {
+	for _, o := range m.Provides {
+		if o.Name == "mesh-bus" {
+			return true
+		}
+	}
+	return false
+}
+
+// rolloutHand mints a machine its credential for the new bus afresh and prints its membership
+// once, for an operator to carry by hand — the rescue for a machine that cannot be reached over
+// any bus: rotated while it still held the old password, or reachable only by ssh. The plaintext
+// exists on this terminal and then only where it is written; the store keeps the hash, and the
+// sealed copy in the machine's declaration is replaced too, so the next push says the same.
+func rolloutHand(ctx context.Context, node string) error {
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+	inv := open.inventory
+
+	known, err := broker.FromEnvironment()
+	if err != nil {
+		return fmt.Errorf("the bus's certificate is not known to this process: %w", err)
+	}
+	busAddress, _, err := broker.OnNATS()
+	if err != nil {
+		return err
+	}
+	if busAddress == "" {
+		return errors.New("this control plane is not on the new bus, so there is no membership to hand out")
+	}
+	_, _, bare := broker.CredentialIn(busAddress)
+	if _, after, has := strings.Cut(bare, "://"); has {
+		bare = after
+	}
+	if _, err := inv.NodeByName(ctx, node); err != nil {
+		return err
+	}
+	p := broker.Principal{Kind: broker.KindNode, Node: node}
+	password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: inventory.BusNode, Node: node})
+	if err != nil {
+		return err
+	}
+	membership, _ := json.Marshal(map[string]string{
+		"broker": bare, "fingerprint": known.Fingerprint, "password": password, "transport": "nats",
+	})
+	key, err := inv.SealingKeyOf(ctx, node)
+	if err != nil {
+		return err
+	}
+	sealed, err := secrets.Seal(key, membership)
+	if err != nil {
+		return err
+	}
+	if err := inv.PutBusMembership(ctx, node, sealed); err != nil {
+		return err
+	}
+	// The one line of output is the membership itself, so it can be piped to the machine without
+	// being read on the way. Everything else goes to stderr.
+	fmt.Fprintf(os.Stderr, "%s's credential is minted afresh. Write this to %s on it and restart its host; "+
+		"then push the machine running the bus so the user list carries the new hash.\n",
+		node, catalogue.BusMembershipPath)
+	fmt.Println(string(membership))
+	return nil
+}
@@ -0,0 +1,93 @@
+package main
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// Whether a mesh could move its bus, read from a real store.
+//
+// The readiness reasoning has its own tests; this is about the gathering — that the question is
+// answered from what the mesh actually holds, on a store with machines and modules in it, without
+// writing anything.
+
+func TestReadinessIsGatheredFromWhatTheMeshHolds(t *testing.T) {
+	inv := inventory.ForTest(t)
+	ctx := context.Background()
+
+	// A mesh mid-change: two machines, the bus module on one of them, a module that speaks and a
+	// module that never does.
+	for _, m := range []catalogue.Manifest{
+		{Module: "nats", Version: "1", BusUsers: "/var/lib/nats-module/conf/accounts.conf",
+			Claims: []catalogue.Claim{{Name: "mesh-broker", Scope: catalogue.ScopeMesh}}},
+		{Module: "gitea", Version: "1", Tools: []string{"repo_create"}},
+		{Module: "wallpaper", Version: "1"},
+	} {
+		if err := inv.RegisterModule(ctx, m, inventory.Source{Repository: "/r"}); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, n := range []string{"anchor", "laptop"} {
+		if _, err := inv.AddNode(ctx, n); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, a := range [][2]string{{"anchor", "nats"}, {"anchor", "gitea"}, {"laptop", "wallpaper"}} {
+		if _, err := inv.Assign(ctx, a[0], a[1]); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	state, err := readinessOf(ctx, inv)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if state.Holder != "anchor" {
+		t.Errorf("the machine holding the bus reads as %q", state.Holder)
+	}
+	if len(state.Nodes) != 2 {
+		t.Errorf("machines read as %v", state.Nodes)
+	}
+	// **A module that never speaks is not counted as missing a credential.** A third of the catalogue
+	// never reaches the bus, and listing those would bury the ones that matter.
+	for _, m := range state.Modules {
+		if strings.HasSuffix(m, "/wallpaper") {
+			t.Errorf("a module that never speaks was counted: %v", state.Modules)
+		}
+	}
+	if len(state.Modules) != 2 {
+		t.Errorf("modules that speak read as %v; expected the bus module and the one with a tool",
+			state.Modules)
+	}
+
+	// Nothing has been minted, so it is not ready — and it says so about each machine by name.
+	why := notReadyOf(state)
+	if len(why) == 0 {
+		t.Fatal("a mesh where nothing has a credential was reported ready to move")
+	}
+	said := strings.Join(why, "\n")
+	for _, name := range []string{"anchor", "laptop"} {
+		if !strings.Contains(said, name) {
+			t.Errorf("the refusal does not name %s: %s", name, said)
+		}
+	}
+
+	// Mint for one machine and it drops out of the complaint, which is how somebody works through it.
+	if _, err := inv.MintBusPassword(ctx, inventory.BusUser{
+		Username: "node.laptop", Kind: inventory.BusNode, Node: "laptop",
+	}); err != nil {
+		t.Fatal(err)
+	}
+	state, err = readinessOf(ctx, inv)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !state.Credentialled["laptop"] {
+		t.Error("a machine that was minted a credential still reads as having none")
+	}
+}
@@ -6,6 +6,7 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"slices"
 	"sort"
 	"strings"
 	"text/tabwriter"
@@ -43,15 +44,16 @@ type seatRow struct {
 // overview would make the one thing the overview is for — what does this mesh have — quietly
 // incomplete.
 func seatsHeld(seats []catalogue.Seat, held []catalogue.Held) ([]seatRow, []catalogue.Held) {
-	defined := map[string]bool{}
 	rows := make([]seatRow, 0, len(seats))
 	for _, s := range seats {
-		defined[s.Name] = true
 		row := seatRow{Seat: s.Name, Scope: s.Scope, Delivers: s.Delivers, Decision: s.Decision,
 			Holders: []seatHolder{}}
 		seen := map[seatHolder]bool{}
 		for _, h := range held {
-			if h.Claim != s.Name || h.Scope != s.Scope {
+			// Resolve the held claim to a seat rather than comparing names, so a record naming a
+			// seat's former name groups under it after a rename (novox/hq ADR 0122).
+			hs, ok := catalogue.SeatNamed(h.Claim)
+			if !ok || hs.Name != s.Name || h.Scope != s.Scope {
 				continue
 			}
 			holder := seatHolder{Node: h.Node, Module: h.Module}
@@ -70,7 +72,8 @@ func seatsHeld(seats []catalogue.Seat, held []catalogue.Held) ([]seatRow, []cata
 	}
 	var outside []catalogue.Held
 	for _, h := range held {
-		if !defined[h.Claim] {
+		// Outside the set only if it resolves to no seat at all — a former name still resolves.
+		if _, ok := catalogue.SeatNamed(h.Claim); !ok {
 			outside = append(outside, h)
 		}
 	}
@@ -83,6 +86,120 @@ func seatsHeld(seats []catalogue.Seat, held []catalogue.Held) ([]seatRow, []cata
 	return rows, outside
 }

+// seatCommand changes the set — the whole point of it being data (novox/hq ADR 0122) — and, since
+// ADR 0131, changes who holds a seat.
+func seatCommand(ctx context.Context, args []string) error {
+	if len(args) == 3 && args[0] == "rename" {
+		from, to := args[1], args[2]
+		open, err := openStores(ctx)
+		if err != nil {
+			return err
+		}
+		defer open.Close()
+		if err := open.inventory.RenameSeat(ctx, from, to); err != nil {
+			return err
+		}
+		fmt.Printf("%s is now %s — its former name still resolves, so nothing is rebuilt, "+
+			"re-registered or frozen (novox/hq ADR 0122)\n", from, to)
+		return nil
+	}
+	if len(args) == 3 && args[1] == "--to" {
+		return handOver(ctx, args[0], args[2])
+	}
+	return fmt.Errorf("seat rename <from> <to>  |  seat <name> --to <node>/<module>")
+}
+
+// handOver makes one assignment the holder of a seat, as one act, so the seat is never without a
+// holder in between (novox/hq ADR 0131, design 28 task 5.3). The control plane finds its own bus
+// through one of these seats; the day it was left empty mid-change is why this exists.
+//
+// Everything that could make the new holder wrong is refused here, before the row is written: the
+// seat must exist, the assignment must exist, and the module must be able to hold the seat —
+// claim it at its scope and provide what it delivers, judged against the store's row. What is
+// **not** checked is whether the module is running yet: that is what `push` confirms afterwards,
+// and refusing to record a handover to a module the node has not started would make the handover
+// impossible to do before the switch instead of as the switch.
+func handOver(ctx context.Context, seatName, to string) error {
+	nodeName, module, ok := strings.Cut(to, "/")
+	if !ok || nodeName == "" || module == "" {
+		return fmt.Errorf("the new holder is named <node>/<module>, not %q", to)
+	}
+	open, err := openStores(ctx)
+	if err != nil {
+		return err
+	}
+	defer open.Close()
+	inv := open.inventory
+
+	seat, known := catalogue.SeatNamed(seatName)
+	if !known {
+		return fmt.Errorf("%q is not a seat this mesh defines — `seats` lists them", seatName)
+	}
+	assigned, err := inv.Assigned(ctx, nodeName)
+	if err != nil {
+		return err
+	}
+	if !slices.Contains(assigned, module) {
+		return fmt.Errorf("%s is not assigned to %s, so it cannot hold anything there — "+
+			"`assign %s %s` first", module, nodeName, nodeName, module)
+	}
+	entries, err := inv.Catalogued(ctx)
+	if err != nil {
+		return err
+	}
+	var m *catalogue.Manifest
+	for i := range entries {
+		if entries[i].Manifest.Module == module {
+			m = &entries[i].Manifest
+		}
+	}
+	if m == nil {
+		return fmt.Errorf("%s is assigned but not in the catalogue, which should not happen", module)
+	}
+	var was string
+	holdings, err := inv.Holdings(ctx)
+	if err != nil {
+		return err
+	}
+	for _, h := range holdings {
+		if hs, ok := catalogue.SeatNamed(h.Claim); ok && hs.Name == seat.Name {
+			was = h.Node
+		}
+	}
+
+	// **Recording who already holds the seat is not making a new holder, and is not judged like
+	// one.** On a mesh that predates the record, the first handover has to begin by writing down
+	// the standing holder — otherwise the next holder cannot be assigned beside it, because two
+	// eligible claimants with nothing on record are refused. That standing holder may no longer
+	// satisfy what the seat delivers (the row moved under it, on purpose, as ADR 0131's first step),
+	// and it holds regardless: derivation never read that column. So when nothing is on record and
+	// the named assignment is the one holding by derivation, only the claim itself is checked here.
+	// Every *change* of holder is judged in full.
+	claimsIt := false
+	for _, c := range m.Claims {
+		if cs, ok := catalogue.SeatNamed(c.Name); ok && cs.Name == seat.Name && c.At() == seat.Scope {
+			claimsIt = true
+		}
+	}
+	if was == "" && claimsIt {
+		fmt.Printf("nothing was on record for %s; recording %s on %s as its standing holder\n",
+			seat.Name, module, nodeName)
+	} else if err := catalogue.CanHold(*m, seat); err != nil {
+		return fmt.Errorf("%s cannot hold %s: %w", module, seat.Name, err)
+	}
+	if err := inv.HoldSeat(ctx, seat.Name, seat.Scope, nodeName, module); err != nil {
+		return err
+	}
+	fmt.Printf("%s is held by %s on %s\n", seat.Name, module, nodeName)
+	if was != "" && was != nodeName {
+		fmt.Printf("  `push %s` and `push %s` send both machines what changed\n", was, nodeName)
+	} else {
+		fmt.Printf("  `push %s` sends the machine what changed; every other machine that reads the "+
+			"seat is re-declared by `push --behind`\n", nodeName)
+	}
+	return nil
+}
+
 func seatsCommand(ctx context.Context, args []string) error {
 	set := flag.NewFlagSet("seats", flag.ContinueOnError)
 	asJSON := set.Bool("json", false, "the same, as JSON")
@@ -35,13 +35,13 @@ func TestEverySeatIsListedIncludingTheOnesNobodyHolds(t *testing.T) {

 func TestANodeSeatListsEveryMachineHoldingIt(t *testing.T) {
 	rows, _ := seatsHeld(catalogue.Seats(), []catalogue.Held{
-		{Claim: "the-packet-filter", Scope: catalogue.ScopeNode, Node: "node2", Module: "nftables"},
-		{Claim: "the-packet-filter", Scope: catalogue.ScopeNode, Node: "anchor", Module: "nftables"},
+		{Claim: "node-packet-filter", Scope: catalogue.ScopeNode, Node: "node2", Module: "nftables"},
+		{Claim: "node-packet-filter", Scope: catalogue.ScopeNode, Node: "anchor", Module: "nftables"},
 		// Resolved twice, reported once: a machine is one holder however many passes saw it.
-		{Claim: "the-packet-filter", Scope: catalogue.ScopeNode, Node: "anchor", Module: "nftables"},
+		{Claim: "node-packet-filter", Scope: catalogue.ScopeNode, Node: "anchor", Module: "nftables"},
 	})
 	for _, r := range rows {
-		if r.Seat != "the-packet-filter" {
+		if r.Seat != "node-packet-filter" {
 			continue
 		}
 		if len(r.Holders) != 2 || r.Holders[0].Node != "anchor" || r.Holders[1].Node != "node2" {
@@ -38,6 +38,12 @@ func (s sendable) Body() ([]byte, error) {
 	if s.Adoption != nil {
 		envelope["adoption"] = s.Adoption
 	}
+	// An empty declaration is deliberate here — the node owns nothing the mesh put there
+	// (novox/hq issue 127) — and the host refuses an empty body unless it is told the emptiness
+	// is meant, so a truncated or mis-composed body is never mistaken for "own nothing".
+	if len(s.Resources) == 0 {
+		envelope["owns_nothing"] = true
+	}
 	return json.Marshal(envelope)
 }

@@ -355,3 +355,25 @@ func TestTheMachineSideOfAMappingIsMovedEverywhereTheNumberIsUsed(t *testing.T)
 		t.Fatalf("the consumer is told the forge answers on %v", told)
 	}
 }
+
+func TestAnEmptyDeclarationSaysOwnsNothing(t *testing.T) {
+	// The host refuses an empty body unless told the emptiness is meant (novox/hq issue 127).
+	body, err := sendable{}.Body()
+	if err != nil {
+		t.Fatal(err)
+	}
+	var env map[string]any
+	if err := json.Unmarshal(body, &env); err != nil {
+		t.Fatal(err)
+	}
+	if env["owns_nothing"] != true {
+		t.Fatalf("an empty declaration must mark owns_nothing; got %v", env)
+	}
+	// A declaration with resources does not carry the marker.
+	body, _ = sendable{Resources: []map[string]any{{"id": "x"}}}.Body()
+	var env2 map[string]any
+	_ = json.Unmarshal(body, &env2)
+	if _, present := env2["owns_nothing"]; present {
+		t.Fatalf("a non-empty declaration must not mark owns_nothing; got %v", env)
+	}
+}
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"time"

+	"github.com/novox/mesh-controller/internal/catalogue"
 	"github.com/novox/mesh-controller/internal/identity"
 	"github.com/novox/mesh-controller/internal/inventory"
 	"github.com/novox/mesh-controller/internal/licences"
@@ -72,6 +73,14 @@ func migrate(ctx context.Context) error {
 		}
 		fmt.Printf("provided %s\n", m.Module)
 	}
+	// The seats the mesh ships with, into the table that now holds the set (novox/hq ADR 0122).
+	// Idempotent: fills an empty table on first boot, adds a seat a release ships, and leaves an
+	// operator's changes in the table as they are.
+	added, err := inv.SeedSeats(ctx, catalogue.DefaultSeats())
+	if err != nil {
+		return err
+	}
+	fmt.Printf("seeded %d seat(s)\n", added)
 	return nil
 }

@@ -85,6 +94,18 @@ func openInventory(ctx context.Context) (*inventory.Inventory, error) {
 		inv.Close()
 		return nil, err
 	}
+	// Load the seat set from the store, so the control plane reads the set as data rather than as
+	// the slice it was compiled with (novox/hq ADR 0122). A store not yet seeded — or one whose
+	// seat table a migration has not reached — returns nothing, and UseSeats leaves the compiled
+	// defaults in force: the set is never emptied by a read that found nothing, which would refuse
+	// every claim. So this can only ever replace the defaults with what the mesh actually holds.
+	if seats, err := inv.Seats(ctx); err == nil {
+		catalogue.UseSeats(seats)
+	}
+	// And the former names, so a reference to a seat's old name resolves after a rename (ADR 0122).
+	if aliases, err := inv.Aliases(ctx); err == nil {
+		catalogue.UseAliases(aliases)
+	}
 	return inv, nil
 }

@@ -6,7 +6,9 @@ import (
 	"flag"
 	"fmt"
 	"strings"
+	"time"

+	"github.com/novox/mesh-controller/internal/catalogue"
 	"github.com/novox/mesh-controller/internal/inventory"
 	"github.com/novox/mesh-controller/internal/link"
 )
@@ -218,3 +220,305 @@ func notNow(err error) error {
 	}
 	return err
 }
+
+// SourceMoved is the forge announcing a merge: every module recorded as built from that
+// repository and branch is marked as moved to the merge commit, and built — bases first, so a
+// module that stands on another's artifact is built after it and not against the old one
+// (novox/hq 04-ISSUES/131). Nothing is pushed here: what a finished build does to the machines
+// running the module is the upgrade's decision, taken when the catalogue announces it.
+func (f following) SourceMoved(ctx context.Context, m link.SourceMoved) error {
+	inv := f.open.inventory
+	entries, err := inv.Catalogued(ctx)
+	if err != nil {
+		return notNow(err)
+	}
+	read, err := inv.ReadRepositories(ctx)
+	if err != nil {
+		return notNow(err)
+	}
+
+	// Two kinds of module are affected by one merge, and they are affected differently.
+	//
+	// A module **built from** this repository and branch has moved: the mesh records the new commit
+	// as what its source now has, and only what the merge actually changed is rebuilt. A module that
+	// only **packages source from** it has not moved — its own source is somewhere else, at the
+	// commit it already records — so it is rebuilt and its record left alone. Writing this commit as
+	// its source would make it permanently behind a repository its manifest does not come from.
+	var from, packaging []inventory.Entry
+	already := 0
+	for _, e := range entries {
+		switch {
+		case sourceIs(e.Source, m):
+			if e.Source.BuiltFrom == m.Commit {
+				already++
+				continue
+			}
+			// **A merge older than the last look at the source is history, not a move.** The forge
+			// announces what it finds merged, and an old merge surfacing late would otherwise move
+			// the recorded head backwards and rebuild everything built from that repository, once
+			// per old merge (2026-09-28).
+			if isHistory(m.MergedAt, e.Source.Seen) {
+				continue
+			}
+			from = append(from, e)
+		case readsFrom(read[e.Manifest.Module], m):
+			packaging = append(packaging, e)
+		}
+	}
+	if len(from) == 0 && len(packaging) == 0 {
+		// "Already built from it" and "nothing reads it" are different facts, and reading the first
+		// as the second sends somebody looking for a broken trigger when the mesh is up to date.
+		if already > 0 {
+			fmt.Printf("%s/%s merged into %s (%.8s); %d module(s) the mesh holds are already built "+
+				"from it\n", m.Owner, m.Repo, m.Base, m.Commit, already)
+			return nil
+		}
+		fmt.Printf("%s/%s merged into %s (%.8s); nothing the mesh holds reads it\n",
+			m.Owner, m.Repo, m.Base, m.Commit)
+		return nil
+	}
+	// The same judgement for the packaging kind, against the newest look at that repository by
+	// anything built from it: they keep no record of it themselves, and a replayed old merge should
+	// not rebuild them either.
+	if isHistory(m.MergedAt, lastLookAt(entries, m)) {
+		packaging = nil
+	}
+	touched := whatTheMergeTouched(from, entries, m)
+	for _, e := range touched {
+		if err := inv.SourceMoved(ctx, e.Manifest.Module, m.Commit); err != nil {
+			return notNow(err)
+		}
+	}
+	moved := append(append([]inventory.Entry{}, touched...), packaging...)
+	if len(moved) == 0 {
+		fmt.Printf("%s/%s merged into %s (%.8s); it changed nothing any module the mesh holds is "+
+			"built from\n", m.Owner, m.Repo, m.Base, m.Commit)
+		return nil
+	}
+	against, err := inv.BuiltAgainst(ctx)
+	if err != nil {
+		return notNow(err)
+	}
+	ordered := orderByBases(moved, against)
+	names := make([]string, 0, len(ordered))
+	for _, e := range ordered {
+		names = append(names, e.Manifest.Module)
+	}
+	fmt.Printf("%s/%s merged into %s (%.8s); building %s\n",
+		m.Owner, m.Repo, m.Base, m.Commit, strings.Join(names, ", "))
+	if len(packaging) > 0 {
+		var also []string
+		for _, e := range packaging {
+			also = append(also, e.Manifest.Module)
+		}
+		fmt.Printf("  %s package source from it, so they are rebuilt and their own source record "+
+			"is left where it is\n", strings.Join(also, ", "))
+	}
+	var failed []string
+	for _, e := range ordered {
+		source := buildSource{Repository: e.Source.Repository, Seat: e.Source.Seat}
+		if err := buildOne(ctx, source, e.Source.Path, e.Source.Ref, 20*time.Minute); err != nil {
+			fmt.Printf("  %s: %v\n", e.Manifest.Module, err)
+			failed = append(failed, e.Manifest.Module)
+			// A base that failed is a reason to stop: what stands on it would be built against
+			// the old one, and report success (novox/hq 04-ISSUES/131).
+			if standsOn(ordered, e.Manifest.Module, against) {
+				fmt.Printf("  stopping: %s is a base of what was still to build\n", e.Manifest.Module)
+				break
+			}
+		}
+	}
+	if len(failed) > 0 {
+		fmt.Printf("%d of %d not built: %s\n", len(failed), len(ordered), strings.Join(failed, ", "))
+	}
+	return nil
+}
+
+// sourceIs is whether a recorded source is the repository and branch a merge announced. A source on
+// the git seat is recorded as its path on the forge; one elsewhere as the URL it was cloned from.
+// An empty recorded ref is the repository's default branch, which is what a merge into the base
+// branch of the forge's default means.
+func sourceIs(s inventory.Source, m link.SourceMoved) bool {
+	if !sameRepository(s.Repository, m) {
+		return false
+	}
+	return s.Ref == "" || s.Ref == m.Base
+}
+
+// sameRepository is whether a recorded repository is the one a merge names, in either spelling it
+// may have been recorded in: a path on the git seat, or the URL it was cloned from.
+func sameRepository(repository string, m link.SourceMoved) bool {
+	want := strings.ToLower(m.Owner + "/" + m.Repo)
+	repo := strings.ToLower(strings.TrimSuffix(repository, ".git"))
+	return repo == want || strings.HasSuffix(repo, "/"+want) ||
+		(m.CloneURL != "" && repo == strings.ToLower(strings.TrimSuffix(m.CloneURL, ".git")))
+}
+
+// readsFrom is whether a module's build read the repository a merge names: the second repository its
+// recipe packages source from. Its ref must be the branch that moved, or unset — the same rule a
+// module's own source follows.
+func readsFrom(read []inventory.ReadRepository, m link.SourceMoved) bool {
+	for _, r := range read {
+		if sameRepository(r.Repository, m) && (r.Ref == "" || r.Ref == m.Base) {
+			return true
+		}
+	}
+	return false
+}
+
+// lastLookAt is the most recent look at this repository by anything built from it.
+func lastLookAt(entries []inventory.Entry, m link.SourceMoved) time.Time {
+	var newest time.Time
+	for _, e := range entries {
+		if sameRepository(e.Source.Repository, m) && e.Source.Seen.After(newest) {
+			newest = e.Source.Seen
+		}
+	}
+	return newest
+}
+
+// whatTheMergeTouched narrows the modules built from a repository to the ones the merge changed.
+//
+// **A change inside no module's own directory is a change to what they share.** The forge lists the
+// files a merge changed; a module is affected when one of them is inside its own directory, when it
+// is built from the repository's root — everything there is its source — or when some changed file
+// belongs to no module's directory at all, which is how a shared file, a build recipe or a
+// dependency at the root rebuilds everything built from that repository.
+//
+// A change inside *another* module's directory is that module's business and not this one's, even
+// when the mesh does not hold that module: `known` is every module this repository is known to hold,
+// whatever branch it was registered from. That is also the limit of this — a repository whose shared
+// code sits inside a directory the mesh has never seen a module in reads as shared, and everything
+// is rebuilt. Rebuilding too much is the safe direction: the fault this whole path exists for is a
+// mesh that believes it is current and is not (novox/hq 04-ISSUES/131).
+func whatTheMergeTouched(candidates, known []inventory.Entry, m link.SourceMoved) []inventory.Entry {
+	// Nothing said about the files, or not all of them said: everything built from it is affected.
+	if len(m.Paths) == 0 || m.PathsTruncated {
+		return candidates
+	}
+	var dirs []string
+	for _, e := range known {
+		if e.Source.Path != "" && sameRepository(e.Source.Repository, m) {
+			dirs = append(dirs, e.Source.Path)
+		}
+	}
+	for _, p := range m.Paths {
+		if !insideAny(p, dirs) {
+			return candidates
+		}
+	}
+	var out []inventory.Entry
+	for _, e := range candidates {
+		if e.Source.Path == "" || anyInside(m.Paths, e.Source.Path) {
+			out = append(out, e)
+		}
+	}
+	return out
+}
+
+// inside is whether a changed file is in a directory: that directory itself, or under it.
+func inside(path, dir string) bool {
+	dir = strings.Trim(dir, "/")
+	path = strings.TrimPrefix(path, "/")
+	return path == dir || strings.HasPrefix(path, dir+"/")
+}
+
+// insideAny is whether a changed file is in any of these directories.
+func insideAny(path string, dirs []string) bool {
+	for _, dir := range dirs {
+		if inside(path, dir) {
+			return true
+		}
+	}
+	return false
+}
+
+// anyInside is whether any of these changed files is in a directory.
+func anyInside(paths []string, dir string) bool {
+	for _, p := range paths {
+		if inside(p, dir) {
+			return true
+		}
+	}
+	return false
+}
+
+// orderByBases is the entries with every base before what stands on it: a module whose build stood
+// on another's artifact comes after that module. Entries outside the set are not waited for — they
+// are not being rebuilt. Stable for what has no order between it.
+//
+// `against` is what each module's newest build stood on (inventory.BuiltAgainst): the edges are
+// derived from builds, not declared, because a recorded manifest no longer carries `build.on`.
+func orderByBases(entries []inventory.Entry, against map[string][]string) []inventory.Entry {
+	inSet := map[string]bool{}
+	for _, e := range entries {
+		inSet[e.Manifest.Module] = true
+	}
+	var out []inventory.Entry
+	placed := map[string]bool{}
+	var place func(e inventory.Entry, seen map[string]bool)
+	place = func(e inventory.Entry, seen map[string]bool) {
+		name := e.Manifest.Module
+		if placed[name] || seen[name] {
+			return
+		}
+		seen[name] = true
+		for _, base := range entries {
+			if base.Manifest.Module != name && inSet[base.Manifest.Module] && standsOnModule(e, base.Manifest.Module, against) {
+				place(base, seen)
+			}
+		}
+		placed[name] = true
+		out = append(out, e)
+	}
+	for _, e := range entries {
+		place(e, map[string]bool{})
+	}
+	return out
+}
+
+// standsOn is whether anything in the set is built on the named module's artifacts.
+func standsOn(entries []inventory.Entry, module string, against map[string][]string) bool {
+	for _, e := range entries {
+		if standsOnModule(e, module, against) {
+			return true
+		}
+	}
+	return false
+}
+
+// standsOnModule is whether an entry's build stood on the named module: by what its newest build
+// recorded it was handed (`artifact-store://<module>/<artifact>@…`, the module's own artifact), or
+// — for a module registered from a manifest and not yet built — by the base its manifest names.
+func standsOnModule(e inventory.Entry, module string, against map[string][]string) bool {
+	if e.Manifest.Module == module {
+		return false
+	}
+	if e.Manifest.Build != nil {
+		for _, on := range e.Manifest.Build.On {
+			if on.Module == module {
+				return true
+			}
+		}
+	}
+	prefix := catalogue.ArtifactStoreScheme + module + "/"
+	for _, ref := range against[e.Manifest.Module] {
+		if strings.HasPrefix(ref, prefix) {
+			return true
+		}
+	}
+	return false
+}
+
+// isHistory is whether a merge made at mergedAt predates the last time the source was seen. A merge
+// with no time on it is taken as news: refusing it would silence a forge that says less.
+func isHistory(mergedAt string, seen time.Time) bool {
+	if mergedAt == "" || seen.IsZero() {
+		return false
+	}
+	at, err := time.Parse(time.RFC3339, mergedAt)
+	if err != nil {
+		return false
+	}
+	return at.Before(seen)
+}
@@ -1,19 +1,22 @@
 module github.com/novox/mesh-controller

-go 1.25.0
+go 1.26.0

 require (
 	github.com/jackc/pgx/v5 v5.10.0
-	github.com/rabbitmq/amqp091-go v1.14.0
-	golang.org/x/crypto v0.55.0
+	github.com/nats-io/nats.go v1.54.0
+	golang.org/x/crypto v0.57.0
 )

 require (
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
-	golang.org/x/net v0.57.0 // indirect
-	golang.org/x/sync v0.22.0 // indirect
-	golang.org/x/sys v0.47.0 // indirect
-	golang.org/x/text v0.41.0 // indirect
+	github.com/klauspost/compress v1.20.0 // indirect
+	github.com/nats-io/nkeys v0.4.16 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
+	golang.org/x/net v0.58.0 // indirect
+	golang.org/x/sync v0.23.0 // indirect
+	golang.org/x/sys v0.48.0 // indirect
+	golang.org/x/text v0.42.0 // indirect
 )
@@ -9,27 +9,31 @@ github.com/jackc/pgx/v5 v5.10.0 h1:VhSvgU2jSli8o3AqIEOTJr7rZwAEUVo4E4XhR94Zfr0=
 github.com/jackc/pgx/v5 v5.10.0/go.mod h1:mal1tBGAFfLHvZzaYh77YS/eC6IX9OWbRV1QIIM0Jn4=
 github.com/jackc/puddle/v2 v2.2.2 h1:PR8nw+E/1w0GLuRFSmiioY6UooMp6KJv0/61nB7icHo=
 github.com/jackc/puddle/v2 v2.2.2/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
+github.com/klauspost/compress v1.20.0 h1:a3C1ke2ohxFymNlb2HWAHjDeKCI90scRskErZkR0ezA=
+github.com/klauspost/compress v1.20.0/go.mod h1:LUdAzn7YLVvxLpc7y3V1m40wESHTgc1422pwwBSKYuI=
+github.com/nats-io/nats.go v1.54.0 h1:vsXoOxjHp/GmPUN+EcI7uOf/uB+iAP+kEsAFNQN0yzA=
+github.com/nats-io/nats.go v1.54.0/go.mod h1:y+DZoD1oBOYfZTU681eTUiUjI0vbqYGixNVFHcjHJ0k=
+github.com/nats-io/nkeys v0.4.16 h1:rd5oAuLOb8mnAycB0xleuEBNS1pVVnN0fv/FF34Eypg=
+github.com/nats-io/nkeys v0.4.16/go.mod h1:llLgWoI0o4z/Q57q2R1kHfmocyhGV6VG/U18Glg1Afs=
+github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
+github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/rabbitmq/amqp091-go v1.14.0 h1:RSaT7aOKt/OrkVUyswPDW29lnRz9psuGmfZFBmLqLek=
-github.com/rabbitmq/amqp091-go v1.14.0/go.mod h1:Hy4jKW5kQART1u+JkDTF9YYOQUHXqMuhrgxOEeS7G4o=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
-go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
-go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
-golang.org/x/crypto v0.55.0 h1:+KWHjbgOaAQ66dh/YlkZKHlz9ZUlq61AFirAR9ntP8M=
-golang.org/x/crypto v0.55.0/go.mod h1:uq0V9dE/fzQuJtbnL+2EhWOE63vo164FY8xqEnV9xis=
-golang.org/x/net v0.57.0 h1:K5+3DljvIuDG9/Jv9rvyMywYNFCQ9RSUY6OOTTkT+tE=
-golang.org/x/net v0.57.0/go.mod h1:KpXc8iv+r3XplLAG/f7Jsf9RPszJzdR0f58q9vGOuEU=
-golang.org/x/sync v0.22.0 h1:SZjpbeLmrCk4xhRSZFNZW5gFUeCeFgjekvI/+gfScek=
-golang.org/x/sync v0.22.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
-golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
-golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
-golang.org/x/text v0.41.0 h1:vz/seA0lnX87Othu2f/0L24RcgrXD9/YFTSuGjj3rH8=
-golang.org/x/text v0.41.0/go.mod h1:jvf1O8ajNzZqhSrQBPbutR/EB83Cc0CFrezNQIwbb5M=
+golang.org/x/crypto v0.57.0 h1:3ZVCjf8Ggz7zneR/EHRVx68Ctf+2pmIMP2UFhh9cC6M=
+golang.org/x/crypto v0.57.0/go.mod h1:Fdz0i5U6CoizGwLda9DttjSk6qlZo25zYNtR+ycvuZA=
+golang.org/x/net v0.58.0 h1:ynWG7rqYi4ccpTEuPZ2QGWHktVEM9DMCj9yzDE0Q7To=
+golang.org/x/net v0.58.0/go.mod h1:YwCddHnFlT7eLQqVprV19OnhLGtc5xOKgE0RyqgfWAU=
+golang.org/x/sync v0.23.0 h1:KameEIfc1IkluZyXWLn39Wd4tURc6GbCiISGiZm2bQk=
+golang.org/x/sync v0.23.0/go.mod h1:sUUOizhqBxiL6pEWpqNLUiaJn1ShEbZ6BBqskPbjZm0=
+golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
+golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
+golang.org/x/text v0.42.0 h1:JbOZXgfeCPU9gacVtYliJqOhD+zhrEqK4LfdpmlUZqI=
+golang.org/x/text v0.42.0/go.mod h1:ojzP1Z+2QtioaF8DTtO8K5q7JWVVYwZKenzujK0Zd0E=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
@@ -0,0 +1,125 @@
+package broker
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// Do the emitters and the consumers of a catalogue agree?
+//
+// **The check that was missing** (novox/hq 04-ISSUES/127). Every manifest was individually
+// well-formed and every derivation individually correct, and no cross-module subscription in the
+// mesh matched anything: a consumer's declaration derived into a namespace nobody publishes to.
+// Nothing failed, because a subscription that matches nothing is not an error — it is silence.
+//
+// The comparison has to be over the whole catalogue, because the two halves live in different
+// manifests, and it cannot simply demand that every consumed event have a live emitter: a module
+// may be installed long before the one whose events it wants. So the rule is narrower and still
+// catches this: **where the emitter is present, it must emit what the consumer asked for.**
+
+// AConsumer is one module's interest in another's events, as this check needs it.
+type AConsumer struct {
+	Module   string
+	Consumes []string
+}
+
+// AnEmitter is one module's events.
+type AnEmitter struct {
+	Module string
+	Emits  []string
+}
+
+// Disagreements are the consumed events whose emitter is in the catalogue and does not emit them.
+//
+// Returned as sentences rather than as structs: every one of them is read by a person deciding
+// whether a manifest or a catalogue is wrong, and a pair of names without the reason is a puzzle.
+func Disagreements(emitters []AnEmitter, consumers []AConsumer, seats []DeclaredSeat) []string {
+	emits := map[string]map[string]bool{}
+	for _, e := range emitters {
+		if emits[e.Module] == nil {
+			emits[e.Module] = map[string]bool{}
+		}
+		for _, name := range e.Emits {
+			emits[e.Module][name] = true
+		}
+	}
+	// A seat's events are published by its holder under the seat's name, so a consumer naming the
+	// seat is naming something real even though no module declares it as its own.
+	for _, s := range seats {
+		if len(s.Emits) == 0 {
+			continue
+		}
+		if emits[s.Name] == nil {
+			emits[s.Name] = map[string]bool{}
+		}
+		for _, name := range s.Emits {
+			emits[s.Name][name] = true
+		}
+	}
+
+	var out []string
+	for _, c := range consumers {
+		for _, pattern := range c.Consumes {
+			emitter, event, named := strings.Cut(pattern, ".")
+			// Every event from everyone, or every event from one module: both are deliberate and
+			// neither names a particular event to check.
+			if !named || emitter == "*" || emitter == catalogueTheRest || event == catalogueTheRest {
+				continue
+			}
+			known, present := emits[emitter]
+			if !present {
+				// Not installed here, which is ordinary: a module lives in its own repository and
+				// may be registered later. Nothing to compare, so nothing to say.
+				continue
+			}
+			if matchesAny(event, known) {
+				continue
+			}
+			out = append(out, fmt.Sprintf(
+				"%s consumes %q and %s emits %s — so that subscription would match nothing, and "+
+					"nothing would report it",
+				c.Module, pattern, emitter, listOf(known)))
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// matchesAny says whether one of an emitter's event names satisfies a consumer's pattern.
+func matchesAny(pattern string, emitted map[string]bool) bool {
+	want := strings.Split(pattern, ".")
+	for name := range emitted {
+		if matches(want, strings.Split(name, ".")) {
+			return true
+		}
+	}
+	return false
+}
+
+func matches(pattern, name []string) bool {
+	for i, part := range pattern {
+		if part == catalogueTheRest {
+			return i < len(name)
+		}
+		if i >= len(name) {
+			return false
+		}
+		if part != "*" && part != name[i] {
+			return false
+		}
+	}
+	return len(pattern) == len(name)
+}
+
+func listOf(names map[string]bool) string {
+	if len(names) == 0 {
+		return "nothing"
+	}
+	out := make([]string, 0, len(names))
+	for n := range names {
+		out = append(out, n)
+	}
+	sort.Strings(out)
+	return strings.Join(out, ", ")
+}
@@ -0,0 +1,236 @@
+package broker
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// **Do the catalogue's emitters and consumers agree?**
+//
+// This is the check whose absence let issue 127 stand: every manifest was individually well-formed,
+// every derivation individually correct, and no cross-module subscription in the mesh matched
+// anything. A subscription that matches nothing is not an error — it is silence — so nothing
+// anywhere reported it.
+//
+// It compares what one manifest asks to hear against what another says it emits. It cannot demand
+// that every consumed event have a live emitter, because a module lives in its own repository and
+// may be registered long before the one whose events it wants. Where the emitter *is* here, it must
+// emit what the consumer asked for.
+func TestTheCataloguesEmittersAndConsumersAgree(t *testing.T) {
+	emitters, consumers, seats := theCataloguesEvents(t)
+
+	if bad := Disagreements(emitters, consumers, seats); len(bad) > 0 {
+		t.Fatalf("%d subscription(s) in the catalogue would match nothing:\n  %s",
+			len(bad), strings.Join(bad, "\n  "))
+	}
+}
+
+// And the check itself catches the thing it exists for, so it cannot pass by doing nothing.
+func TestTheAgreementCheckCatchesASubscriptionThatMatchesNothing(t *testing.T) {
+	bad := Disagreements(
+		[]AnEmitter{{Module: "builder", Emits: []string{"built"}}},
+		[]AConsumer{{Module: "mesh-catalog", Consumes: []string{"builder.finished"}}},
+		nil)
+	if len(bad) != 1 {
+		t.Fatalf("a consumer asking for an event its emitter does not emit was not caught: %v", bad)
+	}
+	if !strings.Contains(bad[0], "builder.finished") || !strings.Contains(bad[0], "built") {
+		t.Fatalf("the report names neither what was asked for nor what is emitted: %s", bad[0])
+	}
+
+	// A module that is not here is not a disagreement: it may be registered later.
+	if bad := Disagreements(nil,
+		[]AConsumer{{Module: "plex", Consumes: []string{"sonarr.download.completed"}}}, nil); len(bad) != 0 {
+		t.Fatalf("a consumer whose emitter is not installed was reported: %v", bad)
+	}
+
+	// A wildcard over emitters is deliberate and names no particular event to check.
+	if bad := Disagreements([]AnEmitter{{Module: "sonarr", Emits: []string{"download.completed"}}},
+		[]AConsumer{{Module: "plex", Consumes: []string{"*.download.completed"}}}, nil); len(bad) != 0 {
+		t.Fatalf("a wildcard over emitters was reported: %v", bad)
+	}
+
+	// A consumer of a role's event whose role does not emit it is caught, which is what stops the
+	// catalogue check above from passing by knowing nothing about roles.
+	if bad := Disagreements(nil,
+		[]AConsumer{{Module: "mesh-catalog", Consumes: []string{"mesh-build-machine.finished"}}},
+		[]DeclaredSeat{{Name: "mesh-build-machine", Emits: []string{"built"}}}); len(bad) != 1 {
+		t.Fatalf("a consumer of a role event the role does not emit was not caught: %v", bad)
+	}
+
+	// An event published under a seat's name is real even though no module declares it as its own.
+	if bad := Disagreements(nil,
+		[]AConsumer{{Module: "watcher", Consumes: []string{"mesh-artifact-store.image.pushed"}}},
+		[]DeclaredSeat{{Name: "the-artifact-store", Emits: []string{"image.pushed"}}}); len(bad) != 0 {
+		t.Fatalf("an event a seat emits was reported as matching nothing: %v", bad)
+	}
+}
+
+func theCataloguesEvents(t *testing.T) ([]AnEmitter, []AConsumer, []DeclaredSeat) {
+	t.Helper()
+	root := filepath.Join("..", "..", "..", "mesh-catalog", "modules")
+	entries, err := os.ReadDir(root)
+	if err != nil {
+		t.Skipf("catalogue sibling not present: %v", err)
+	}
+	var emitters []AnEmitter
+	var consumers []AConsumer
+	// The mesh's own roles, which emit under the seat's name rather than any module's (novox/hq
+	// ADR 0121). Without these the check skips every consumer of a role's event as "the emitter is
+	// not installed" — which is how it passed vacuously the first time one existed.
+	var seats []DeclaredSeat
+	for _, own := range catalogue.SeatsWithAProtocol() {
+		seats = append(seats, DeclaredSeat{Name: own.Name, Accepts: own.Accepts, Emits: own.Emits})
+	}
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		raw, err := os.ReadFile(filepath.Join(root, e.Name(), "module.json"))
+		if err != nil {
+			continue
+		}
+		var m struct {
+			Module   string   `json:"module"`
+			Emits    []string `json:"emits"`
+			Consumes []string `json:"consumes"`
+			Seats    []struct {
+				Name  string   `json:"name"`
+				Emits []string `json:"emits"`
+			} `json:"seats"`
+		}
+		if err := json.Unmarshal(raw, &m); err != nil {
+			t.Fatalf("%s: %v", e.Name(), err)
+		}
+		if len(m.Emits) > 0 {
+			emitters = append(emitters, AnEmitter{Module: m.Module, Emits: m.Emits})
+		}
+		if len(m.Consumes) > 0 {
+			consumers = append(consumers, AConsumer{Module: m.Module, Consumes: m.Consumes})
+		}
+		for _, s := range m.Seats {
+			seats = append(seats, DeclaredSeat{Name: s.Name, Emits: s.Emits})
+		}
+	}
+	if len(emitters) == 0 {
+		t.Skip("no manifests found beside this checkout")
+	}
+	return emitters, consumers, seats
+}
+
+// **Do the derived subjects meet, not just the names?**
+//
+// The check above compares what a consumer asks for against what an emitter says it emits, by name. It
+// passed while the catalogue's subscription pointed at `mesh.mod.mesh-build-machine.event.built` — a
+// module namespace for a role's event, which no emitter owns. The names agreed; the subjects did not,
+// and the graph stayed empty.
+//
+// So this compares the thing that actually has to match: the subject a consumer subscribes against the
+// subject an emitter publishes. It is the last place the two halves can be held together, because
+// after this the server is the only thing that knows and it says nothing — a subscription that matches
+// nothing is silence.
+func TestTheCataloguesDerivedSubjectsMeet(t *testing.T) {
+	emitters, consumers, seats := theCataloguesEvents(t)
+
+	// Every subject something publishes: a module's own events, and the events of every role.
+	published := map[string]bool{}
+	for _, e := range emitters {
+		for _, name := range e.Emits {
+			published["mesh.mod."+e.Module+".event."+name] = true
+		}
+	}
+	for _, s := range seats {
+		for _, name := range s.Emits {
+			published["mesh.seat."+s.Name+".event."+name] = true
+		}
+	}
+
+	byName := map[string]DeclaredSeat{}
+	for _, s := range seats {
+		byName[s.Name] = s
+	}
+
+	var lonely []string
+	for _, c := range consumers {
+		principal := Principal{Kind: KindModule, Node: "one", Module: c.Module, PasswordHash: "x"}
+		for _, want := range c.Consumes {
+			emitter, event, named := strings.Cut(want, ".")
+			if named {
+				if s, isASeat := byName[emitter]; isASeat {
+					principal.Watches = append(principal.Watches,
+						Seat{Name: s.Name, Emits: []string{event}})
+					continue
+				}
+			}
+			principal.Consumes = append(principal.Consumes, want)
+		}
+		perms, err := PermissionsFor(principal)
+		if err != nil {
+			t.Fatalf("%s: %v", c.Module, err)
+		}
+		for _, subject := range perms.Subscribe {
+			if !strings.Contains(subject, ".event.") {
+				continue
+			}
+			if reaches(subject, published) {
+				continue
+			}
+			// A wildcard over emitters reaches whatever arrives later, and an emitter that is not
+			// installed is ordinary — both are already excused by the check above, so only a subject
+			// that can never match anything gets here.
+			if strings.Contains(subject, "*") || strings.Contains(subject, ">") {
+				continue
+			}
+			lonely = append(lonely, c.Module+" subscribes "+subject+", which nothing publishes")
+		}
+	}
+	if len(lonely) > 0 {
+		sort.Strings(lonely)
+		t.Fatalf("%d subscription(s) derive to a subject no emitter owns:\n  %s",
+			len(lonely), strings.Join(lonely, "\n  "))
+	}
+}
+
+// And it catches the thing it exists for: a role's event read as a module's.
+func TestTheDerivedSubjectCheckCatchesARolesEventReadAsAModules(t *testing.T) {
+	published := map[string]bool{"mesh.seat.mesh-build-machine.event.built": true}
+	// What the derivation produced before a consumed seat name was resolved as one.
+	if reaches("mesh.mod.mesh-build-machine.event.built", published) {
+		t.Fatal("a module namespace was treated as reaching a role's event, which is the bug")
+	}
+	// And the corrected one does reach it.
+	if !reaches("mesh.seat.mesh-build-machine.event.built", published) {
+		t.Fatal("the role's own subject does not reach the role's event")
+	}
+}
+
+// reaches says whether a subscribed subject admits any published one.
+func reaches(subject string, published map[string]bool) bool {
+	for p := range published {
+		if admitsSubject(strings.Split(subject, "."), strings.Split(p, ".")) {
+			return true
+		}
+	}
+	return false
+}
+
+func admitsSubject(pattern, subject []string) bool {
+	for i, token := range pattern {
+		if token == ">" {
+			return i < len(subject)
+		}
+		if i >= len(subject) {
+			return false
+		}
+		if token != "*" && token != subject[i] {
+			return false
+		}
+	}
+	return len(pattern) == len(subject)
+}
@@ -1,67 +0,0 @@
-package broker_test
-
-import (
-	"regexp"
-	"testing"
-
-	"github.com/novox/mesh-controller/internal/broker"
-	"github.com/novox/mesh-controller/internal/link"
-)
-
-// The names are written twice, so a test keeps them agreeing.
-//
-// `link` imports `broker`, so `broker` cannot import `link` — the queue and exchange names
-// therefore exist in both. A scoped account naming a queue nothing publishes to produces a
-// builder that takes no work and says nothing about why, which is the worst kind of silence.
-//
-// An external test package, because it may import both without either importing the other.
-func TestTheNamesTheBrokerScopesAreTheNamesTheLinkUses(t *testing.T) {
-	for _, agreed := range []struct {
-		what     string
-		scoped   string
-		actually string
-	}{
-		{"the build queue", broker.BuildQueueName, link.BuildQueue},
-		{"the exchange", broker.ExchangeName, link.Exchange},
-		{"a node's queue", broker.QueueFor("somewhere"), link.QueueFor("somewhere")},
-	} {
-		if agreed.scoped != agreed.actually {
-			t.Errorf("%s: the broker scopes %q and the link uses %q",
-				agreed.what, agreed.scoped, agreed.actually)
-		}
-	}
-}
-
-func TestABuilderMayWriteToAReplyQueueAndReadNoNodesDeclarations(t *testing.T) {
-	// The scoping, checked as patterns rather than by connecting: what it may write must include
-	// the queue an asker actually waits on, and what it may read must not include any node's.
-	//
-	// This exists because the first version scoped writes to `amq.gen-*` — the name one broker
-	// happens to generate — and the builder built, could not answer, and the connection simply
-	// closed saying only "not allowed to publish to exchange \'\'". Answering through the
-	// exchange is what removed the need for any of that.
-	write := regexp.MustCompile("^" + regexp.QuoteMeta(broker.ExchangeName) + "$")
-	if !write.MatchString(broker.ExchangeName) {
-		t.Error("a builder may not write to the exchange, so it can take work and never answer")
-	}
-	// And not the default exchange, where permission is per exchange rather than per queue — a
-	// builder allowed to use it could publish into any node's queue.
-	//
-	// Confirmed against a real broker as well, and worth recording how that nearly went wrong:
-	// an unconfirmed publish is asynchronous, so a refusal arrives as a channel close afterwards
-	// and a naive check reports success. With publisher confirms the broker's refusal is
-	// immediate. **A negative security assertion made against an asynchronous call is not an
-	// assertion.**
-	if write.MatchString("") {
-		t.Error("a builder may publish to the default exchange, and so into any node's queue")
-	}
-
-	read := regexp.MustCompile("^" + regexp.QuoteMeta(broker.BuildQueueName) + "$")
-	if !read.MatchString(broker.BuildQueueName) {
-		t.Error("a builder may not read the build queue")
-	}
-	if read.MatchString(link.QueueFor("someone-else")) {
-		// A build machine is not a node, and a node's queue carries its declarations.
-		t.Error("a builder may read another machine's declarations")
-	}
-}
@@ -66,6 +66,19 @@ func FromEnvironment() (Broker, error) {
 	if err != nil {
 		return Broker{}, err
 	}
+	// **One bus, one address** (novox/hq ADR 0131). Everything the mesh hands out — a token, a
+	// machine's membership, a person's credential — must name the bus the control plane itself is
+	// connected to; the setting above predates the move and, on a mesh that has moved, still names
+	// the broker it moved from. The first person issued after the move was handed the retired
+	// broker's port and could not connect to anything (2026-09-28).
+	//
+	// Read from the credential rather than from a second setting somebody keeps in step: the
+	// control plane cannot be wrong about where it is connected.
+	if bus, on, err := OnNATS(); err == nil && on {
+		if where := strings.TrimPrefix(BareAddress(bus), "nats://"); where != "" {
+			address = where
+		}
+	}
 	return Broker{Address: address, Fingerprint: fingerprint}, nil
 }

@@ -194,16 +194,3 @@ func TestTheAddressPortFollowsThePortTwin(t *testing.T) {
 		t.Fatalf("the address is %q; the node put the bus on 5679", b.Address)
 	}
 }
-
-func TestTheManagementPortFollowsThePortTwin(t *testing.T) {
-	t.Setenv(ManagementVar, "http://guest:guest@127.0.0.1:15672")
-	t.Setenv(ManagementVar+"_FILE", "")
-	t.Setenv(ManagementVar+"_PORT", "15673")
-	m, err := ManagementFromEnvironment()
-	if err != nil {
-		t.Fatal(err)
-	}
-	if m.base.Host != "127.0.0.1:15673" {
-		t.Fatalf("the management API is at %q; the node put it on 15673", m.base.Host)
-	}
-}
@@ -0,0 +1,237 @@
+package broker
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// Streams and consumers derived from what modules declare.
+//
+// The mesh's own four exist before any module does (streams.go). Everything here is the other
+// half: a seat's stream comes into being when the module declaring it is **registered**, and a
+// consumer when a module is **assigned** — which is why ADR 0116's task 1.4 had to be narrowed to
+// the foundation set. Neither has happened at genesis.
+//
+// All of it is a pure function of declarations. The controller is still the only writer; this is
+// only what it writes.
+
+// A Consumer is a durable subscription the controller creates on a module's behalf. A module
+// declares what it reacts to, never how delivery works, so it does not name these and cannot
+// misconfigure them.
+type Consumer struct {
+	Name   string
+	Stream string
+	// Filters are the subjects this consumer receives. One consumer per module with several
+	// filters, rather than one per consumed event: its ack subject is derived from its name, and
+	// a module with five consumers would need five ack permissions to ack its own deliveries.
+	Filters []string
+	// Queue is the queue group, set for a seat's worker so that "exactly one holder" survives a
+	// seat later being relaxed to several. Authority and delivery are kept separate on purpose.
+	Queue string
+	// Push asks the server to deliver to a subject rather than wait to be pulled.
+	//
+	// For the mesh's own consumer, where the controller wants every message to arrive in the one
+	// loop it already runs: pulling would mean a second goroutine fetching batches and handing
+	// them over, and a loop that acts on one message at a time is the property the store window
+	// depends on. A queue group implies this, because a group has nothing to pull from.
+	Push bool
+	// AckWaitSeconds before an unacknowledged delivery is redelivered.
+	AckWaitSeconds int
+	// MaxDeliver before the message is dead-lettered; zero for the mesh's default.
+	MaxDeliver int
+	Why        string
+}
+
+// seatStreamName is the stream holding a seat's inbound work. Named after the seat rather than
+// the module holding it, because the holder can change and the queued work must not care — which
+// is the whole reason a caller addresses a seat instead of a module.
+func seatStreamName(seat string) string { return "SEAT_" + upperSnake(seat) }
+
+// SeatStreams is one work queue per declared seat, created when the declaring module is
+// registered rather than when it is assigned.
+//
+// **The stream exists before anyone holds the seat, and that is the point.** Work queues until a
+// holder appears, so installing the telegram module a week after something started sending to it
+// flushes the backlog instead of having lost it. A stream created at assignment would make "the
+// holder is not here yet" mean "your messages are gone".
+func SeatStreams(seats []DeclaredSeat) []Stream {
+	sorted := append([]DeclaredSeat(nil), seats...)
+	sort.Slice(sorted, func(i, j int) bool { return sorted[i].Name < sorted[j].Name })
+
+	var out []Stream
+	for _, s := range sorted {
+		if len(s.Accepts) == 0 {
+			// A seat that only emits and serves needs no stream: its events ride EVENTS and its
+			// tools are core request/reply, which is never persisted.
+			continue
+		}
+		retain := s.RetainSeconds
+		if retain == 0 {
+			retain = 7 * 24 * 60 * 60
+		}
+		out = append(out, Stream{
+			Name:      seatStreamName(s.Name),
+			Subjects:  []string{"mesh.seat." + s.Name + ".accept.>"},
+			Retention: RetentionWorkQueue,
+			MaxAge:    retain,
+			Why: fmt.Sprintf("work submitted to the %s seat; one holder consumes it, and it "+
+				"queues while nobody does", s.Name),
+		})
+	}
+	return out
+}
+
+// A DeclaredSeat is a seat as the catalogue knows it. Mirrored here rather than imported so this
+// package stays free of the catalogue's own types — the same reason the host mirrors the
+// contracts instead of importing the sdk.
+type DeclaredSeat struct {
+	Name    string
+	Accepts []string
+	// Emits are the verbs the seat's holder publishes under the seat's own name. An event about a
+	// role belongs here rather than in the holder's namespace, because the name then outlives
+	// whoever fills it (novox/hq ADR 0121, 04-ISSUES/127).
+	Emits []string
+	// Serves are the verbs the holder answers, request and reply.
+	Serves        []string
+	RetainSeconds int
+}
+
+// ConsumerFor is the durable consumer a module's declarations imply, or false when it subscribes
+// to nothing and needs none.
+//
+// One per module, with every consumed subject as a filter, because its ack permission is derived
+// from its name: a module with a consumer per event would need an ack permission per consumer,
+// and the permission list would stop being derivable from the declaration.
+func ConsumerFor(p Principal) (Consumer, bool) {
+	// A module that reacts to anything — a module's events or a role's (novox/hq ADR 0121). Watching
+	// a role was missing here, so the one module that does it got no consumer at all: it started,
+	// connected, and its graph stayed empty with nothing anywhere reporting why.
+	if p.Kind != KindModule || (len(p.Consumes) == 0 && len(p.Watches) == 0) {
+		return Consumer{}, false
+	}
+	perms, err := PermissionsFor(p)
+	if err != nil {
+		return Consumer{}, false
+	}
+	// Events, wherever they live: a module's own namespace, and the namespace of any role it watches
+	// (novox/hq ADR 0121). Tool subjects and inboxes are subscribed directly and are not a consumer's
+	// business, which is why this is a filter and not the whole list.
+	var filters []string
+	for _, s := range perms.Subscribe {
+		if strings.Contains(s, ".event.") {
+			filters = append(filters, s)
+		}
+	}
+	if len(filters) == 0 {
+		return Consumer{}, false
+	}
+	sort.Strings(filters)
+	return Consumer{
+		Name:           consumerDurable(p),
+		Stream:         consumerStream(p),
+		Filters:        filters,
+		AckWaitSeconds: 30,
+		MaxDeliver:     5,
+		Why:            "what " + p.Module + " declared it consumes; after max-deliver it dead-letters",
+	}, true
+}
+
+// HolderConsumerFor is the worker a seat's holder gets on that seat's work queue.
+//
+// **A queue group even though the seat guarantees one holder.** The seat is *authority* — who may
+// be the telegram sender — and the queue group is *delivery*. Tie delivery to the seat and the
+// day somebody allows two holders for throughput, every message is processed twice with nothing
+// reporting it. Kept separate, relaxing one changes nothing about the other.
+func HolderConsumerFor(node, module string, seat DeclaredSeat) (Consumer, bool) {
+	if len(seat.Accepts) == 0 {
+		return Consumer{}, false
+	}
+	return Consumer{
+		Name:           "SEAT_" + upperSnake(seat.Name) + "_worker",
+		Stream:         seatStreamName(seat.Name),
+		Filters:        []string{"mesh.seat." + seat.Name + ".accept.>"},
+		Queue:          "holders",
+		AckWaitSeconds: 60,
+		MaxDeliver:     5,
+		Why: fmt.Sprintf("%s on %s holds %s; it acknowledges after the work is done, so a "+
+			"crash mid-work redelivers rather than loses", module, node, seat.Name),
+	}, true
+}
+
+// NodeConsumer is the durable consumer a node reads its own declaration through.
+//
+// **Derived from a node existing, and created by the controller, because a host cannot create it.**
+// A host's account may subscribe its own declaration subject and publish its own ack subject, and
+// reaches no part of the JetStream API — which is correct (the controller is the only writer of
+// consumer definitions, design 25 §3) and means the consumer must be waiting before the host binds
+// to it. Named after the node, because the node's ack grant is `$JS.ACK.NODES.<node>.>` and a
+// consumer named anything else is one the host cannot acknowledge a delivery from.
+//
+// **No max-deliver, and a long ack wait.** A declaration is settled only after the node has applied
+// it and reported, which is minutes on a machine pulling images; and a declaration the mesh cannot
+// get a node to accept is not one to dead-letter, because the stream keeps only the newest per node
+// anyway — so there is exactly one message per node to redeliver, for as long as that node is away.
+func NodeConsumer(node string) Consumer {
+	return Consumer{
+		Name:           node,
+		Stream:         "NODES",
+		Filters:        []string{"mesh.node." + node + ".declare"},
+		Push:           true,
+		AckWaitSeconds: 300,
+		Why: "how " + node + " hears what it should be; last-per-subject, so a node that was away " +
+			"gets exactly the current declaration and nothing older",
+	}
+}
+
+// AssertNodeConsumers brings every known node's declaration consumer into being.
+//
+// Asserted on start as well as created at enrolment, for the reason the streams are: a mesh raised
+// from a restored backup, or one whose bus was recreated, has node records and no consumers, and a
+// node whose consumer is missing hears nothing while everything else about it looks correct.
+func AssertNodeConsumers(e Ensurer, nodes []string) error {
+	for _, n := range nodes {
+		if err := e.EnsureConsumer(NodeConsumer(n)); err != nil {
+			return fmt.Errorf("asserting how %s hears its declaration: %w", n, err)
+		}
+	}
+	return nil
+}
+
+// AllOverlaps reports subject filters claimed by more than one stream, across the mesh's own and
+// every derived one.
+//
+// NATS refuses an overlapping stream rather than merging it (verified against nats-server 2.10:
+// "subjects overlap with an existing stream"), so this is not a subtle divergence — it is a
+// registration that fails. Catching it here names both streams, before a half-applied mesh does.
+func AllOverlaps(seats []DeclaredSeat) []string {
+	all := append(MeshStreams(), SeatStreams(seats)...)
+	seen := map[string]string{}
+	var clashes []string
+	for _, s := range all {
+		for _, subject := range s.Subjects {
+			if first, ok := seen[subject]; ok {
+				clashes = append(clashes, fmt.Sprintf("%s and %s both claim %s", first, s.Name, subject))
+				continue
+			}
+			seen[subject] = s.Name
+		}
+	}
+	sort.Strings(clashes)
+	return clashes
+}
+
+// upperSnake makes a stream name from a seat name. NATS stream names may not contain a dot,
+// a space or a wildcard, and a hyphen is legal but reads badly beside the mesh's own.
+func upperSnake(s string) string {
+	out := []rune(s)
+	for i, r := range out {
+		switch {
+		case r >= 'a' && r <= 'z':
+			out[i] = r - 32
+		case r == '-' || r == '.':
+			out[i] = '_'
+		}
+	}
+	return string(out)
+}
@@ -0,0 +1,155 @@
+package broker
+
+import (
+	"strings"
+	"testing"
+)
+
+func telegramSeat() DeclaredSeat {
+	return DeclaredSeat{Name: "telegram-sender", Accepts: []string{"send"}}
+}
+
+// The stream exists from registration, not assignment: work queues until a holder appears, so
+// installing the module a week later flushes the backlog rather than having lost it.
+func TestASeatGetsAWorkQueueOfItsOwn(t *testing.T) {
+	got := SeatStreams([]DeclaredSeat{telegramSeat()})
+	if len(got) != 1 {
+		t.Fatalf("expected one stream, got %d", len(got))
+	}
+	s := got[0]
+	if s.Retention != RetentionWorkQueue {
+		t.Fatalf("a seat's inbound queue retains as %q; one holder must take each message once", s.Retention)
+	}
+	if s.Subjects[0] != "mesh.seat.telegram-sender.accept.>" {
+		t.Fatalf("filters on %v", s.Subjects)
+	}
+}
+
+// A seat that only emits and serves needs no stream: its events ride EVENTS and its tools are
+// core request/reply, which is never persisted.
+func TestASeatThatAcceptsNothingGetsNoStream(t *testing.T) {
+	if got := SeatStreams([]DeclaredSeat{{Name: "announcer"}}); len(got) != 0 {
+		t.Fatalf("a seat with no inbound work got %d stream(s)", len(got))
+	}
+}
+
+// Retention belongs to whoever owns the namespace, and a seat owns its own.
+func TestASeatsRetentionIsItsOwn(t *testing.T) {
+	s := SeatStreams([]DeclaredSeat{{Name: "slow", Accepts: []string{"work"}, RetainSeconds: 30 * 24 * 60 * 60}})
+	if s[0].MaxAge != 30*24*60*60 {
+		t.Fatalf("the seat's declared retention was not used: %d", s[0].MaxAge)
+	}
+	d := SeatStreams([]DeclaredSeat{telegramSeat()})
+	if d[0].MaxAge == 0 {
+		t.Fatal("a seat that declares no retention got an unbounded queue")
+	}
+}
+
+// NATS refuses an overlapping stream outright, so a clash here is a registration that fails.
+func TestNoDerivedStreamOverlapsTheMeshsOwn(t *testing.T) {
+	seats := []DeclaredSeat{telegramSeat(), {Name: "licensing-master", Accepts: []string{"report"}}}
+	if c := AllOverlaps(seats); len(c) != 0 {
+		t.Fatalf("overlapping filters: %v", c)
+	}
+}
+
+// One consumer per module, with every consumed subject as a filter — because its ack permission
+// is derived from its name, and a consumer per event would need an ack permission per consumer.
+func TestAModuleGetsOneConsumerCarryingEveryFilter(t *testing.T) {
+	c, ok := ConsumerFor(Principal{Kind: KindModule, Node: "one", Module: "audit",
+		Consumes: []string{"shop.order.placed", "billing.invoice.sent"}, PasswordHash: "x"})
+	if !ok {
+		t.Fatal("a module that consumes got no consumer")
+	}
+	if len(c.Filters) != 2 {
+		t.Fatalf("expected both subjects as filters, got %v", c.Filters)
+	}
+	perms, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "audit",
+		Consumes: []string{"shop.order.placed"}, PasswordHash: "x"})
+	ack := "$JS.ACK." + c.Stream + "." + c.Name + ".>"
+	found := false
+	for _, p := range perms.Publish {
+		if p == ack {
+			found = true
+		}
+	}
+	if !found {
+		t.Fatalf("the consumer is named %q but the ack permission is %v; a module could not ack "+
+			"its own deliveries", c.Name, perms.Publish)
+	}
+}
+
+// A module that subscribes to nothing needs no consumer, and creating one would leave an object
+// nothing reads and everything has to maintain.
+func TestAModuleThatConsumesNothingGetsNoConsumer(t *testing.T) {
+	if _, ok := ConsumerFor(Principal{Kind: KindModule, Node: "one", Module: "shop",
+		Emits: []string{"order.placed"}, PasswordHash: "x"}); ok {
+		t.Fatal("a pure emitter got a consumer")
+	}
+}
+
+// The seat is authority and the queue group is delivery. Tie them together and the day somebody
+// allows two holders, every message is processed twice with nothing reporting it.
+func TestAHoldersWorkerUsesAQueueGroupAnyway(t *testing.T) {
+	c, ok := HolderConsumerFor("one", "telegram", telegramSeat())
+	if !ok {
+		t.Fatal("the holder of a seat with inbound work got no worker")
+	}
+	if c.Queue == "" {
+		t.Fatal("the worker is not in a queue group, so a second holder would double-process")
+	}
+	if c.Stream != "SEAT_TELEGRAM_SENDER" {
+		t.Fatalf("the worker reads %q, not the seat's own stream", c.Stream)
+	}
+	if c.MaxDeliver == 0 {
+		t.Fatal("a failing worker would redeliver forever rather than dead-letter")
+	}
+}
+
+// The stream is named after the seat, not its holder: the holder can change and the queued work
+// must not care.
+func TestASeatsStreamIsNamedAfterTheSeat(t *testing.T) {
+	name := seatStreamName("telegram-sender")
+	if strings.Contains(name, "telegram-sender") {
+		t.Fatalf("%q keeps characters a stream name may not hold", name)
+	}
+	if name != "SEAT_TELEGRAM_SENDER" {
+		t.Fatalf("unexpected stream name %q", name)
+	}
+}
+
+// A node hears its declaration through a consumer only the controller can make.
+//
+// The three things that would each break it silently: a name other than the node's is one the host
+// cannot acknowledge a delivery from, because its ack grant is derived from the node's name; a
+// filter other than its own declaration subject is a node reading another's; and a pull consumer is
+// one the host cannot bind a channel to without creating something, which it has no authority for.
+func TestANodesDeclarationConsumerIsWhatItsOwnGrantAllows(t *testing.T) {
+	c := NodeConsumer("anchor")
+	if c.Name != "anchor" {
+		t.Fatalf("named %q, so the node cannot ack from it: its grant is $JS.ACK.NODES.anchor.>", c.Name)
+	}
+	if c.Stream != "NODES" {
+		t.Fatalf("on stream %q rather than the one declarations live in", c.Stream)
+	}
+	if len(c.Filters) != 1 || c.Filters[0] != "mesh.node.anchor.declare" {
+		t.Fatalf("filters %v, which is not this node's own declaration and nothing else", c.Filters)
+	}
+	if !c.Push {
+		t.Fatal("pulled, which a host cannot do: pulling needs the JetStream API and a host reaches none of it")
+	}
+	if c.MaxDeliver != 0 {
+		t.Fatalf("max-deliver %d: a declaration a node has not taken yet is not one to dead-letter, "+
+			"because the stream holds exactly one per node", c.MaxDeliver)
+	}
+
+	// And the grant the node actually gets has to match, or none of the above matters.
+	perms, err := PermissionsFor(Principal{Kind: KindNode, Node: "anchor"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Without the ack grant every declaration a node receives is redelivered for ever; without the
+	// subscribe grant its consumer delivers to nobody.
+	has(t, perms.Publish, "$JS.ACK.NODES."+c.Name+".>")
+	has(t, perms.Subscribe, c.Filters[0])
+}
@@ -0,0 +1,126 @@
+package broker
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strings"
+	"testing"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+// **The first user list the installer carries must be the one the controller would compose.**
+//
+// At genesis there is no mesh to write the bus's user list, so the installer carries one: the
+// controller's own account, at a bootstrap password, the way the store is reached at
+// `postgres:bootstrap` (novox/hq design 25 §4, task 1.7). It is written by hand in a template and
+// derived in code here, which is two statements of one fact — so this compares them.
+//
+// Getting it wrong is the worst kind of silent: a controller whose carried permissions are narrower
+// than the ones it derives comes up, connects, and is refused on the first thing it tries, with an
+// authorisation error that names a subject and not the template that forgot it. And a mesh cannot be
+// raised twice to find out.
+func TestTheInstallersFirstUserListIsWhatTheControllerWouldCompose(t *testing.T) {
+	accounts := theCarriedAccounts(t)
+
+	want, err := PermissionsFor(Principal{Kind: KindController, PasswordHash: "x"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	carriedPub := subjectsIn(accounts, "publish")
+	carriedSub := subjectsIn(accounts, "subscribe")
+
+	if diff := missing(want.Publish, carriedPub); len(diff) > 0 {
+		t.Errorf("the installer's user list does not let the controller publish %v — it would come up "+
+			"and be refused on the first thing it tried", diff)
+	}
+	if diff := missing(want.Subscribe, carriedSub); len(diff) > 0 {
+		t.Errorf("the installer's user list does not let the controller subscribe %v", diff)
+	}
+	// And nothing wider than what it derives, or genesis quietly grants a privilege the composition
+	// takes away again on the first push.
+	if diff := missing(carriedPub, want.Publish); len(diff) > 0 {
+		t.Errorf("the installer's user list lets the controller publish %v, which it does not derive", diff)
+	}
+	if diff := missing(carriedSub, want.Subscribe); len(diff) > 0 {
+		t.Errorf("the installer's user list lets the controller subscribe %v, which it does not derive", diff)
+	}
+
+	// The credential is the bootstrap one and the hash really is of it, because a hash of something
+	// else is a controller that cannot log in to the bus it was just given.
+	hash := regexp.MustCompile(`\$2[aby]?\$[0-9]+\$[A-Za-z0-9./]{53}`).FindString(accounts)
+	if hash == "" {
+		t.Fatal("the installer's user list carries no password hash")
+	}
+	if err := bcrypt.CompareHashAndPassword([]byte(hash), []byte("bootstrap")); err != nil {
+		t.Fatalf("the carried hash does not verify the bootstrap credential the template also carries: %v", err)
+	}
+}
+
+// theCarriedAccounts is the accounts file the installer's template writes at genesis.
+func theCarriedAccounts(t *testing.T) string {
+	t.Helper()
+	path := filepath.Join("..", "..", "..", "mesh-host", "examples", "foundation-first-node-nats.lock")
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		t.Skipf("the host's checkout is not beside this one: %v", err)
+	}
+	// The template is JSON with line comments, which is how every one of them is written.
+	var lines []string
+	for _, l := range strings.Split(string(raw), "\n") {
+		if !strings.HasPrefix(strings.TrimSpace(l), "//") {
+			lines = append(lines, l)
+		}
+	}
+	var bundle struct {
+		Resources []map[string]any `json:"resources"`
+	}
+	if err := json.Unmarshal([]byte(strings.Join(lines, "\n")), &bundle); err != nil {
+		t.Fatalf("the template is not readable: %v", err)
+	}
+	for _, r := range bundle.Resources {
+		if r["id"] == "bus-accounts" {
+			content, _ := r["content"].(string)
+			if content == "" {
+				t.Fatal("the template's accounts file is empty, so the bus would refuse every connection")
+			}
+			return content
+		}
+	}
+	t.Fatal("the template carries no accounts file, so a mesh raised from it has a bus nobody may use")
+	return ""
+}
+
+// subjectsIn reads one allow-list out of a composed accounts file.
+func subjectsIn(accounts, which string) []string {
+	found := regexp.MustCompile(which + `: \{ allow: \[([^\]]*)\]`).FindStringSubmatch(accounts)
+	if len(found) != 2 {
+		return nil
+	}
+	var out []string
+	for _, part := range strings.Split(found[1], ",") {
+		if s := strings.Trim(strings.TrimSpace(part), `"`); s != "" {
+			out = append(out, s)
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// missing is what is in want and not in got.
+func missing(want, got []string) []string {
+	have := map[string]bool{}
+	for _, g := range got {
+		have[g] = true
+	}
+	var out []string
+	for _, w := range want {
+		if !have[w] {
+			out = append(out, w)
+		}
+	}
+	return out
+}
@@ -0,0 +1,213 @@
+package broker
+
+import (
+	"crypto/sha256"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/nats-io/nats.go"
+)
+
+// The JetStream side of the controller: the one place the mesh's streams and consumers are
+// actually created.
+//
+// Everything that decides *what* they are is pure and lives beside this (streams.go, derived.go).
+// This is only the part that talks to a server, kept small on purpose: a bug in a subject filter
+// should be findable in a unit test, and only a bug in "did the server accept it" should need one
+// running.
+
+// A JetStream is a connection to the bus, as the controller uses it.
+type JetStream struct {
+	conn *nats.Conn
+	js   nats.JetStreamContext
+}
+
+// Dial connects and returns the controller's JetStream handle.
+func Dial(url string, opts ...nats.Option) (*JetStream, error) {
+	opts = append(opts, nats.Name("mesh-controller"), nats.Timeout(10*time.Second))
+	// **Pinned, not named.** The bus presents the mesh's own certificate, which names nothing a
+	// public verifier would accept (design 25 §4: a host pins the server's exact certificate and
+	// checks nothing else, and so does this). Without this, the first connection failed with
+	// "certificate is not valid for any names" against a bus that was answering (2026-09-28).
+	if path := strings.TrimSpace(os.Getenv(CertificateVar)); path != "" {
+		pinned, err := pinnedTo(path)
+		if err != nil {
+			return nil, err
+		}
+		opts = append(opts, nats.Secure(pinned))
+	}
+	// **Its own inbox, and nothing wider.** Every principal is granted `_INBOX.<its user>.>` and
+	// no other inbox; the client's default prefix is random, and the server refused the first
+	// subscription to it (2026-09-28). The user is in the URL, so the prefix follows from it.
+	if user, _, _ := CredentialIn(url); user != "" {
+		opts = append(opts, nats.CustomInboxPrefix("_INBOX."+user))
+	}
+	// The address in an error is the address alone. The URL carries this controller's password,
+	// and an error here is written on the assumption it will be logged.
+	where := BareAddress(url)
+	conn, err := nats.Connect(url, opts...)
+	if err != nil {
+		return nil, fmt.Errorf("connecting to the bus at %s: %w", where, err)
+	}
+	js, err := conn.JetStream()
+	if err != nil {
+		conn.Close()
+		return nil, fmt.Errorf("the bus at %s has no JetStream: %w", where, err)
+	}
+	return &JetStream{conn: conn, js: js}, nil
+}
+
+// pinnedTo is a TLS configuration that accepts exactly the certificate in the file and no other:
+// the leaf's SHA-256, compared on every handshake, with the name and the chain deliberately not
+// consulted — a self-signed certificate with no names is the ordinary case for a mesh's bus.
+func pinnedTo(path string) (*tls.Config, error) {
+	want, err := FingerprintOf(path)
+	if err != nil {
+		return nil, err
+	}
+	return PinnedToFingerprint(want), nil
+}
+
+// DialPinned is Dial with the server's certificate pinned by a fingerprint the caller already holds
+// — a module or a build machine that was handed one beside its credential, and has no file.
+func DialPinned(url, fingerprint string, opts ...nats.Option) (*JetStream, error) {
+	if strings.TrimSpace(fingerprint) != "" {
+		opts = append(opts, nats.Secure(PinnedToFingerprint(fingerprint)))
+	}
+	return Dial(url, opts...)
+}
+
+// PinnedToFingerprint accepts exactly the certificate with this SHA-256 and no other.
+func PinnedToFingerprint(want string) *tls.Config {
+	return &tls.Config{
+		InsecureSkipVerify: true, //nolint:gosec // replaced by the pin below, which is stricter
+		MinVersion:         tls.VersionTLS12,
+		VerifyPeerCertificate: func(rawCerts [][]byte, _ [][]*x509.Certificate) error {
+			if len(rawCerts) == 0 {
+				return errors.New("the bus presented no certificate")
+			}
+			sum := sha256.Sum256(rawCerts[0])
+			got := "sha256:" + hex.EncodeToString(sum[:])
+			if got != want {
+				return fmt.Errorf("the bus presented a certificate this mesh does not know (%s…), expected %s…", got[:23], want[:23])
+			}
+			return nil
+		},
+	}
+}
+
+// Conn is the connection itself, for what the mesh keeps off JetStream on purpose — a heartbeat,
+// a tool call — where a lost message is answered by the next one or by a timeout the caller
+// already handles (design 25 §3).
+func (j *JetStream) Conn() *nats.Conn { return j.conn }
+
+// Context is the JetStream handle, for subscribing to what the consumers above define.
+func (j *JetStream) Context() nats.JetStreamContext { return j.js }
+
+func (j *JetStream) Close() {
+	if j.conn != nil {
+		j.conn.Close()
+	}
+}
+
+// EnsureStream creates the stream if it is absent and brings it to match if it is present.
+//
+// **Idempotent, because the controller asserts on every start** rather than creating once at
+// genesis: a stream somebody deleted, or a mesh raised from a restored backup, has to converge
+// rather than run without the guarantee its messages assume.
+//
+// An update, not a delete and recreate. Recreating would discard every message the stream holds
+// and every consumer's position in it — which for CONTROL means the pushes being held through a
+// store restart, exactly the guarantee the stream exists for.
+func (j *JetStream) EnsureStream(s Stream) error {
+	want := &nats.StreamConfig{
+		Name:              s.Name,
+		Subjects:          s.Subjects,
+		Retention:         retentionOf(s.Retention),
+		MaxAge:            time.Duration(s.MaxAge) * time.Second,
+		MaxMsgsPerSubject: int64(s.MaxMsgsPerSubject),
+		Description:       s.Why,
+	}
+	if s.Retention == RetentionLastPerSubject {
+		// Last-per-subject is a limits stream with one message kept per subject, not a
+		// retention policy of its own — the state shape, spelled the way the server spells it.
+		want.Retention = nats.LimitsPolicy
+		want.MaxMsgsPerSubject = 1
+		want.MaxAge = 0
+	}
+
+	switch _, err := j.js.StreamInfo(s.Name); {
+	case err == nil:
+		if _, err := j.js.UpdateStream(want); err != nil {
+			return fmt.Errorf("bringing stream %s to match: %w", s.Name, err)
+		}
+		return nil
+	case errors.Is(err, nats.ErrStreamNotFound):
+		if _, err := j.js.AddStream(want); err != nil {
+			return fmt.Errorf("creating stream %s: %w", s.Name, err)
+		}
+		return nil
+	default:
+		return fmt.Errorf("asking about stream %s: %w", s.Name, err)
+	}
+}
+
+// EnsureConsumer creates or updates one durable consumer.
+//
+// Explicit acknowledgement throughout: a consumer that acknowledges on delivery cannot redeliver
+// work its holder died in the middle of, which is the whole difference between a queue and a
+// firehose.
+func (j *JetStream) EnsureConsumer(c Consumer) error {
+	want := &nats.ConsumerConfig{
+		Durable:        c.Name,
+		AckPolicy:      nats.AckExplicitPolicy,
+		AckWait:        time.Duration(c.AckWaitSeconds) * time.Second,
+		MaxDeliver:     c.MaxDeliver,
+		DeliverGroup:   c.Queue,
+		DeliverSubject: "",
+		Description:    c.Why,
+	}
+	switch len(c.Filters) {
+	case 0:
+	case 1:
+		want.FilterSubject = c.Filters[0]
+	default:
+		want.FilterSubjects = c.Filters
+	}
+	// A queue group needs a delivery subject: a pull consumer has no group, and declaring one
+	// without the other is refused by the server with a message that does not say which half is
+	// missing.
+	if c.Queue != "" || c.Push {
+		want.DeliverSubject = "_DELIVER." + c.Name
+	}
+
+	switch _, err := j.js.ConsumerInfo(c.Stream, c.Name); {
+	case err == nil:
+		if _, err := j.js.UpdateConsumer(c.Stream, want); err != nil {
+			return fmt.Errorf("bringing consumer %s on %s to match: %w", c.Name, c.Stream, err)
+		}
+		return nil
+	case errors.Is(err, nats.ErrConsumerNotFound):
+		if _, err := j.js.AddConsumer(c.Stream, want); err != nil {
+			return fmt.Errorf("creating consumer %s on %s: %w", c.Name, c.Stream, err)
+		}
+		return nil
+	default:
+		return fmt.Errorf("asking about consumer %s on %s: %w", c.Name, c.Stream, err)
+	}
+}
+
+func retentionOf(r Retention) nats.RetentionPolicy {
+	switch r {
+	case RetentionWorkQueue:
+		return nats.WorkQueuePolicy
+	default:
+		return nats.LimitsPolicy
+	}
+}
@@ -0,0 +1,71 @@
+package broker
+
+import (
+	"os"
+	"testing"
+)
+
+// Against a real server, because the questions here are all "does the server accept this" —
+// which a mock would answer by agreeing with whatever this file already believes.
+//
+// Skipped unless MESH_TEST_NATS names one, so the ordinary suite stays fast and offline:
+//
+//	docker run -d --rm --name t -p 14222:4222 nats:2.10-alpine -js
+//	MESH_TEST_NATS=nats://127.0.0.1:14222 go test ./internal/broker/ -run TestAgainstARealServer
+func TestAgainstARealServer(t *testing.T) {
+	url := os.Getenv("MESH_TEST_NATS")
+	if url == "" {
+		t.Skip("MESH_TEST_NATS unset")
+	}
+	js, err := Dial(url)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer js.Close()
+
+	t.Run("the mesh's own streams are accepted", func(t *testing.T) {
+		if err := AssertMeshStreams(js); err != nil {
+			t.Fatal(err)
+		}
+	})
+
+	t.Run("asserting again changes nothing and fails nothing", func(t *testing.T) {
+		if err := AssertMeshStreams(js); err != nil {
+			t.Fatalf("the second assertion failed, so the controller cannot restart: %v", err)
+		}
+	})
+
+	t.Run("a seat's work queue is accepted beside them", func(t *testing.T) {
+		seats := []DeclaredSeat{{Name: "telegram-sender", Accepts: []string{"send"}}}
+		for _, s := range SeatStreams(seats) {
+			if err := js.EnsureStream(s); err != nil {
+				t.Fatal(err)
+			}
+		}
+		if c := AllOverlaps(seats); len(c) != 0 {
+			t.Fatalf("overlaps the server would refuse: %v", c)
+		}
+	})
+
+	t.Run("a module's consumer is accepted and is idempotent", func(t *testing.T) {
+		c, ok := ConsumerFor(Principal{Kind: KindModule, Node: "one", Module: "audit",
+			Consumes: []string{"shop.order.placed", "billing.invoice.sent"}, PasswordHash: "x"})
+		if !ok {
+			t.Fatal("no consumer derived")
+		}
+		if err := js.EnsureConsumer(c); err != nil {
+			t.Fatal(err)
+		}
+		if err := js.EnsureConsumer(c); err != nil {
+			t.Fatalf("the second assertion failed: %v", err)
+		}
+	})
+
+	t.Run("a holder's worker is accepted with its queue group", func(t *testing.T) {
+		c, _ := HolderConsumerFor("one", "telegram",
+			DeclaredSeat{Name: "telegram-sender", Accepts: []string{"send"}})
+		if err := js.EnsureConsumer(c); err != nil {
+			t.Fatal(err)
+		}
+	})
+}
@@ -1,366 +0,0 @@
-package broker
-
-import (
-	"bytes"
-	"context"
-	"encoding/json"
-	"fmt"
-	"github.com/novox/mesh-controller/internal/envfile"
-	"io"
-	"net/http"
-	"net/url"
-	"regexp"
-	"strings"
-	"time"
-)
-
-// The mesh runs the broker, so there is no chicken-and-egg in a node needing an account before it
-// can connect: the account is created when the token is issued, and the one-time secret in that
-// token IS the password. A node's first connection is already authenticated, and enrolment is
-// what happens over it.
-//
-// novox/hq ADR 0004's *a node holds its own identity and nothing else* is why the account is per
-// node rather than shared. A shared enrolment account would let any node consume another's queue,
-// which is the shared-credential fault that record exists to remove, reappearing at the transport.
-
-// ManagementVar holds the broker's management API, credentials included.
-const ManagementVar = "MESH_BROKER_MANAGEMENT"
-
-// safeName is what a node may be called at the broker.
-//
-// The name goes into a URL path and into permission patterns, which are regular expressions. A
-// name carrying a `.` or a `*` would silently widen what that node may reach — so it is
-// constrained here rather than escaped later, because an escape that is forgotten once is a node
-// reading everybody's queues.
-var safeName = regexp.MustCompile(`^[a-z0-9][a-z0-9-]{0,62}$`)
-
-// Management is the broker's administrative interface.
-type Management struct {
-	base   *url.URL
-	client *http.Client
-}
-
-// ManagementFromEnvironment reads where the management API is, if it is configured.
-//
-// On the port MESH_BROKER_MANAGEMENT_PORT names when the node moved it (novox/hq 04-ISSUES/102);
-// the URL's own port otherwise.
-func ManagementFromEnvironment() (*Management, error) {
-	raw, err := envfile.Placed(ManagementVar)
-	if err != nil {
-		return nil, err
-	}
-	if raw == "" {
-		return nil, ErrNotConfigured
-	}
-	base, err := url.Parse(raw)
-	if err != nil || base.Host == "" {
-		// The value carries a password, so it is not quoted back.
-		return nil, fmt.Errorf("%s is not a usable URL", ManagementVar)
-	}
-	return &Management{base: base, client: &http.Client{Timeout: 15 * time.Second}}, nil
-}
-
-// QueueFor is the queue a node consumes from. One per node, named after it.
-func QueueFor(node string) string { return "node." + node }
-
-// ExchangeName is where nodes publish what they have to say. One exchange, and the control plane
-// is the only consumer behind it (novox/hq ADR 0006 — one consumer, so two cannot silently split
-// the traffic between them).
-const ExchangeName = "mesh"
-
-// BuildQueueName is where build work waits. Duplicated from `link` rather than imported, for the
-// same reason QueueFor above is: this package must not depend on the one that uses it, and a
-// constant that differed would be caught by the test that asserts they agree.
-const BuildQueueName = "builds"
-
-// The events bus (novox/hq ADR 0042): one topic exchange every event rides, a second for tool
-// RPC kept apart, and a dead-letter home for a poison event. The foundation owns these — a module's
-// account cannot declare them, only bind its own queue to the events one.
-const (
-	EventsExchangeName = "mesh.events"
-	RPCExchangeName    = "mesh.rpc"
-	DeadExchangeName   = "mesh.events.dead"
-)
-
-// ModuleQueueFor is the durable queue a module consumes its events from — one per module per node
-// (novox/hq ADR 0042), named so the account that may read it is exactly this module's.
-func ModuleQueueFor(node, module string) string { return node + "." + module + ".events" }
-
-// modulePermissions is a module's authority on the bus, derived from its manifest (novox/hq
-// ADR 0043): what it consumes and what it emits, and nothing else. Pure, so the scope is tested as
-// patterns without a broker — the way a builder's is.
-//
-// A note on the limit: the broker's write permission is per exchange, not per routing key (LavinMQ
-// has no topic permissions), so an emitting module is granted the events exchange whole. ADR 0042's
-// origin reservation — a module publishes only under `module.<self>.*` — is stamped by the sdk, not
-// enforced here; that gap is the broker's, and is recorded rather than hidden. A pure consumer like
-// the audit logger is unaffected: it is granted no write to the exchange at all.
-func modulePermissions(node, module string, emits, consumes []string) (configure, write, read string) {
-	queue := regexp.QuoteMeta(ModuleQueueFor(node, module))
-	events := regexp.QuoteMeta(EventsExchangeName)
-	rpc := regexp.QuoteMeta(RPCExchangeName)
-	// A module serves each of its tools on its own queue, namespaced by the module (novox/hq
-	// ADR 0047) — serve.<module>.<tool> — so the account may declare, bind and read exactly its own,
-	// and no other module's.
-	serve := "serve\\." + regexp.QuoteMeta(module) + "\\..*"
-
-	// Declare its own events queue and its own tool serve queues.
-	configure = "^(" + queue + "|" + serve + ")$"
-
-	// Write to bind its queue and serve queues (binding is a write on the queue), and to the RPC
-	// exchange to publish replies (ADR 0047: replies ride mesh.rpc, never the default exchange, which
-	// would let it publish into any queue). To the events exchange only if it emits.
-	writes := []string{queue, serve, rpc}
-	if len(emits) > 0 {
-		writes = append(writes, events)
-	}
-	write = "^(" + strings.Join(writes, "|") + ")$"
-
-	// Read its own queue and serve queues to consume them, and the RPC exchange to bind its serve
-	// queues onto. The events exchange to bind onto only if it consumes.
-	reads := []string{queue, serve, rpc}
-	if len(consumes) > 0 {
-		reads = append(reads, events)
-	}
-	read = "^(" + strings.Join(reads, "|") + ")$"
-	return configure, write, read
-}
-
-// CreateModuleAccount gives an assigned module its own broker account, scoped by what it emits and
-// consumes (novox/hq ADR 0043). The account name carries the node so the same module on two machines
-// holds two accounts, each sealed to its own; the permissions carry the module so one module cannot
-// read another's queue. Generic — the builder is one instance of this rule, not a separate kind.
-func (m *Management) CreateModuleAccount(ctx context.Context, node, module, password string, emits, consumes []string) (string, error) {
-	if !safeName.MatchString(node) {
-		return "", fmt.Errorf("%q cannot be part of a broker account: it is a permission pattern", node)
-	}
-	if !safeName.MatchString(module) {
-		return "", fmt.Errorf("%q cannot be part of a broker account: it is a permission pattern", module)
-	}
-	account := node + "-" + module
-	if !safeName.MatchString(account) {
-		return "", fmt.Errorf("%q is not a usable broker account name", account)
-	}
-
-	if err := m.put(ctx, "/api/users/"+url.PathEscape(account),
-		map[string]string{"password": password, "tags": ""}); err != nil {
-		return "", fmt.Errorf("cannot create the broker account for %s on %s: %w", module, node, err)
-	}
-
-	configure, write, read := modulePermissions(node, module, emits, consumes)
-	if err := m.put(ctx, "/api/permissions/%2f/"+url.PathEscape(account), map[string]string{
-		"configure": configure, "write": write, "read": read,
-	}); err != nil {
-		return "", fmt.Errorf("cannot scope the broker account for %s on %s: %w", module, node, err)
-	}
-	return account, nil
-}
-
-// EnsureModuleQueue declares a consuming module's queue with its dead-letter exchange, idempotently.
-// The foundation declares it because a scoped module account may not: the broker refuses a queue with
-// a dead-letter exchange to a non-administrator (novox/hq ADR 0043), so a consumer passively checks
-// the queue the mesh made rather than declaring its own.
-func (m *Management) EnsureModuleQueue(ctx context.Context, node, module string) error {
-	queue := ModuleQueueFor(node, module)
-	if err := m.put(ctx, "/api/queues/%2f/"+url.PathEscape(queue), map[string]any{
-		"durable":   true,
-		"arguments": map[string]any{"x-dead-letter-exchange": DeadExchangeName},
-	}); err != nil {
-		return fmt.Errorf("cannot declare the queue for %s on %s: %w", module, node, err)
-	}
-	return nil
-}
-
-// EnsureEventExchanges declares the bus's exchanges and the dead-letter home, idempotently. The
-// foundation owns them (a module's account may not declare an exchange), and a dead-letter exchange
-// with no queue behind it drops what it receives — so a durable queue bound to `#` retains a poison
-// event for inspection, which is the whole reason the trail exists.
-func (m *Management) EnsureEventExchanges(ctx context.Context) error {
-	for _, exchange := range []string{EventsExchangeName, RPCExchangeName, DeadExchangeName} {
-		if err := m.put(ctx, "/api/exchanges/%2f/"+url.PathEscape(exchange),
-			map[string]any{"type": "topic", "durable": true}); err != nil {
-			return fmt.Errorf("cannot declare the %s exchange: %w", exchange, err)
-		}
-	}
-	if err := m.put(ctx, "/api/queues/%2f/"+url.PathEscape(DeadExchangeName),
-		map[string]any{"durable": true}); err != nil {
-		return fmt.Errorf("cannot declare the dead-letter queue: %w", err)
-	}
-	if err := m.post(ctx, "/api/bindings/%2f/e/"+url.PathEscape(DeadExchangeName)+
-		"/q/"+url.PathEscape(DeadExchangeName), map[string]string{"routing_key": "#"}); err != nil {
-		return fmt.Errorf("cannot bind the dead-letter queue: %w", err)
-	}
-	return nil
-}
-
-// CreateNodeAccount gives a node its own broker account, with the token's secret as the password.
-//
-// Scoped so a node can reach its own queue and the one exchange, and nothing else. The patterns
-// are anchored: a node called `laptop` must not be able to read `laptop-of-somebody-else`.
-func (m *Management) CreateNodeAccount(ctx context.Context, node, password string) error {
-	if !safeName.MatchString(node) {
-		return fmt.Errorf(
-			"%q cannot be a broker account name: it becomes part of a permission pattern, so it "+
-				"is lower-case letters, digits and dashes", node)
-	}
-
-	if err := m.put(ctx, "/api/users/"+url.PathEscape(node),
-		map[string]string{"password": password, "tags": ""}); err != nil {
-		return fmt.Errorf("cannot create the broker account for %s: %w", node, err)
-	}
-
-	queue := regexp.QuoteMeta(QueueFor(node))
-	if err := m.put(ctx, "/api/permissions/%2f/"+url.PathEscape(node), map[string]string{
-		"configure": "^" + queue + "$",
-		"write":     "^(" + regexp.QuoteMeta(ExchangeName) + "|" + queue + ")$",
-		"read":      "^" + queue + "$",
-	}); err != nil {
-		return fmt.Errorf("cannot scope the broker account for %s: %w", node, err)
-	}
-	return nil
-}
-
-// CreateBuilderAccount scopes an account to taking build work and answering it.
-//
-// **A build machine is not a node**, and giving it a node's account would let it read another
-// machine's declarations. What it needs is narrower and different: read the build queue, and
-// write to the exchange and to whatever temporary queue an asker is waiting on.
-//
-// The reply queues are the reason `write` is not simply the exchange. `RequestBuild` declares an
-// exclusive queue with a generated name and waits on it, so a builder that could not write to it
-// could take work and never answer — which is the failure that looks like a builder that is not
-// running.
-func (m *Management) CreateBuilderAccount(ctx context.Context, name, password string) error {
-	if !safeName.MatchString(name) {
-		return fmt.Errorf(
-			"%q cannot be a broker account name: it becomes part of a permission pattern, so it "+
-				"is lower-case letters, digits and dashes", name)
-	}
-
-	if err := m.put(ctx, "/api/users/"+url.PathEscape(name),
-		map[string]string{"password": password, "tags": ""}); err != nil {
-		return fmt.Errorf("cannot create the broker account for %s: %w", name, err)
-	}
-
-	builds := regexp.QuoteMeta(BuildQueueName)
-	if err := m.put(ctx, "/api/permissions/%2f/"+url.PathEscape(name), map[string]string{
-		// It declares the build queue, because whichever builder starts first must be able to —
-		// and a queue nobody may declare is a queue that exists only if the control plane has
-		// already run, which makes the order they start in matter.
-		"configure": "^" + builds + "$",
-		// Two exchanges, and nothing else. **Not the default exchange**: permission there is
-		// granted per exchange rather than per queue, so a builder allowed to use it could
-		// publish into any node's queue — the privilege a build machine most obviously should
-		// not have. Answers go through the node exchange; announcing what was built goes through
-		// the events exchange, which is a different act with a different audience (novox/hq
-		// ADR 0072). A builder that could answer and not announce would leave the module graph
-		// knowing less than the registry does.
-		"write": "^(" + regexp.QuoteMeta(ExchangeName) + "|" + regexp.QuoteMeta(EventsExchangeName) + ")$",
-		// The build queue and nothing else. Not another machine's declarations.
-		"read": "^" + builds + "$",
-	}); err != nil {
-		return fmt.Errorf("cannot scope the broker account for %s: %w", name, err)
-	}
-	return nil
-}
-
-// RemoveNodeAccount withdraws a node's access.
-func (m *Management) RemoveNodeAccount(ctx context.Context, node string) error {
-	if !safeName.MatchString(node) {
-		return fmt.Errorf("%q is not a broker account name", node)
-	}
-	return m.do(ctx, http.MethodDelete, "/api/users/"+url.PathEscape(node), nil)
-}
-
-// Accounts lists the broker's users, so a picture can be read from the system rather than assumed
-// (novox/hq ADR 0018).
-func (m *Management) Accounts(ctx context.Context) ([]string, error) {
-	body, err := m.get(ctx, "/api/users")
-	if err != nil {
-		return nil, err
-	}
-	var users []struct {
-		Name string `json:"name"`
-	}
-	if err := json.Unmarshal(body, &users); err != nil {
-		return nil, err
-	}
-	names := make([]string, 0, len(users))
-	for _, u := range users {
-		names = append(names, u.Name)
-	}
-	return names, nil
-}
-
-func (m *Management) put(ctx context.Context, path string, body any) error {
-	return m.do(ctx, http.MethodPut, path, body)
-}
-
-func (m *Management) post(ctx context.Context, path string, body any) error {
-	return m.do(ctx, http.MethodPost, path, body)
-}
-
-func (m *Management) get(ctx context.Context, path string) ([]byte, error) {
-	request, err := m.request(ctx, http.MethodGet, path, nil)
-	if err != nil {
-		return nil, err
-	}
-	response, err := m.client.Do(request)
-	if err != nil {
-		return nil, err
-	}
-	defer response.Body.Close()
-	if response.StatusCode >= 300 {
-		return nil, fmt.Errorf("the broker's management API answered %s to GET %s",
-			response.Status, path)
-	}
-	return io.ReadAll(io.LimitReader(response.Body, 1<<20))
-}
-
-func (m *Management) do(ctx context.Context, method, path string, body any) error {
-	request, err := m.request(ctx, method, path, body)
-	if err != nil {
-		return err
-	}
-	response, err := m.client.Do(request)
-	if err != nil {
-		return err
-	}
-	defer response.Body.Close()
-	if response.StatusCode >= 300 {
-		detail, _ := io.ReadAll(io.LimitReader(response.Body, 4096))
-		return fmt.Errorf("the broker's management API answered %s to %s %s: %s",
-			response.Status, method, path, strings.TrimSpace(string(detail)))
-	}
-	return nil
-}
-
-func (m *Management) request(ctx context.Context, method, path string, body any) (*http.Request, error) {
-	var payload io.Reader
-	if body != nil {
-		raw, err := json.Marshal(body)
-		if err != nil {
-			return nil, err
-		}
-		payload = bytes.NewReader(raw)
-	}
-
-	// Path joined by hand rather than through url.Parse: %2f is the default vhost and must reach
-	// the broker still encoded. Parsing would decode it to a slash and address a different route.
-	target := strings.TrimSuffix(m.base.String(), "/")
-	if user := m.base.User; user != nil {
-		target = strings.TrimSuffix(m.base.Scheme+"://"+m.base.Host, "/")
-	}
-	request, err := http.NewRequestWithContext(ctx, method, target+path, payload)
-	if err != nil {
-		return nil, err
-	}
-	if user := m.base.User; user != nil {
-		password, _ := user.Password()
-		request.SetBasicAuth(user.Username(), password)
-	}
-	if body != nil {
-		request.Header.Set("Content-Type", "application/json")
-	}
-	return request, nil
-}
@@ -1,96 +0,0 @@
-package broker_test
-
-import (
-	"context"
-	"encoding/json"
-	"net/http"
-	"net/http/httptest"
-	"regexp"
-	"strings"
-	"testing"
-
-	"github.com/novox/mesh-controller/internal/broker"
-)
-
-// The audit logger consumes everything and emits nothing. Its account must let it declare and read
-// its own queue and read the events exchange to bind onto — and must not reach another module's
-// queue, nor grant any write to the events exchange (novox/hq ADR 0043).
-func TestAConsumerReadsItsOwnQueueAndTheEventsExchangeAndNoOthers(t *testing.T) {
-	// Rebuilt through CreateModuleAccount's own path by asking for the same scope it would apply.
-	// The queue this module reads:
-	mine := broker.ModuleQueueFor("anchor", "audit-logger")
-	other := broker.ModuleQueueFor("anchor", "plex")
-
-	read := scope(t, "read", "anchor", "audit-logger", nil, []string{"#"})
-	if !read.MatchString(mine) {
-		t.Error("the audit logger may not read its own queue, so it consumes nothing")
-	}
-	if !read.MatchString(broker.EventsExchangeName) {
-		t.Error("the audit logger may not read the events exchange, so it cannot bind onto it")
-	}
-	if read.MatchString(other) {
-		t.Error("the audit logger may read another module's queue")
-	}
-
-	// It emits nothing, so it is granted no write to the events exchange — only its own queue, to bind.
-	write := scope(t, "write", "anchor", "audit-logger", nil, []string{"#"})
-	if write.MatchString(broker.EventsExchangeName) {
-		t.Error("a pure consumer was granted write to the events exchange")
-	}
-	if !write.MatchString(mine) {
-		t.Error("the audit logger may not write to its own queue, so it cannot bind it")
-	}
-}
-
-// An emitter is granted the events exchange to write; a consumer is not.
-func TestAnEmitterMayWriteTheEventsExchangeAndAConsumerMayNot(t *testing.T) {
-	emitter := scope(t, "write", "anchor", "umami", []string{"module.umami.site.created"}, nil)
-	if !emitter.MatchString(broker.EventsExchangeName) {
-		t.Error("an emitting module may not write the events exchange, so it cannot emit")
-	}
-}
-
-// scope reconstructs one of the three permission patterns CreateModuleAccount would apply, by
-// reading it back from a captured request against a stub management API.
-func scope(t *testing.T, which, node, module string, emits, consumes []string) *regexp.Regexp {
-	t.Helper()
-	pat := capturePermission(t, which, node, module, emits, consumes)
-	re, err := regexp.Compile(pat)
-	if err != nil {
-		t.Fatalf("the %s pattern does not compile: %v", which, err)
-	}
-	return re
-}
-
-// capturePermission runs CreateModuleAccount against a stub management API and returns the pattern
-// it set for `which` ("configure"/"write"/"read"). The scope is tested where it is applied, not
-// reconstructed by the test — so a change to the mapping cannot pass a test that hard-codes the old
-// one.
-func capturePermission(t *testing.T, which, node, module string, emits, consumes []string) string {
-	t.Helper()
-	var captured map[string]string
-	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if strings.HasPrefix(r.URL.Path, "/api/permissions/") {
-			_ = json.NewDecoder(r.Body).Decode(&captured)
-		}
-		w.WriteHeader(http.StatusNoContent)
-	}))
-	defer server.Close()
-
-	t.Setenv(broker.ManagementVar, server.URL)
-	m, err := broker.ManagementFromEnvironment()
-	if err != nil {
-		t.Fatalf("stub management not usable: %v", err)
-	}
-	if _, err := m.CreateModuleAccount(context.Background(), node, module, "pw", emits, consumes); err != nil {
-		t.Fatalf("CreateModuleAccount: %v", err)
-	}
-	if captured == nil {
-		t.Fatal("no permissions were set")
-	}
-	pattern, ok := captured[which]
-	if !ok {
-		t.Fatalf("no %s permission was set; got %v", which, captured)
-	}
-	return pattern
-}
@@ -0,0 +1,597 @@
+// Composing the bus's own configuration.
+//
+// An account is *composed*, never called for: the controller writes accounts, users and
+// per-subject permissions into one file the host keeps current, and the server reloads it in
+// place (novox/hq ADR 0106 — never through a management API; design 25 §4).
+//
+// Everything here is pure. Given the principals, it returns the file's text — so the whole of the
+// mesh's authority model is testable as strings, with no server.
+//
+// **Permissions are per subject, so a module's own name is the server's to enforce.** ADR 0042
+// reserves a module's origin — it publishes only under its own name — and here that is a refusal
+// rather than something a library promises.
+package broker
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+	"sort"
+	"strings"
+)
+
+// A Kind is what a principal is, which decides the shape of its authority rather than its
+// contents: a module's comes from its declaration, a host's from its node, and the controller's
+// and the enrolment user's are fixed.
+type Kind string
+
+const (
+	KindModule     Kind = "module"
+	KindNode       Kind = "node"
+	KindController Kind = "controller"
+	KindEnrolment  Kind = "enrolment"
+	// KindPerson is somebody reaching the mesh's tools from a workstation (design 25 §7). Its
+	// authority is a list of tools and nothing else — not control, not declarations, not builds,
+	// and no ability to answer anything, because a person asks.
+	KindPerson Kind = "person"
+)
+
+// Seat is a role on the bus as a principal relates to it: the subjects it accepts, and those it
+// emits (novox/hq ADR 0118, design 29 §5).
+type Seat struct {
+	Name     string
+	Accepts  []string
+	Emits    []string
+	Serves   []string
+	Versions []string // protocol versions served beside the current one; empty for v1 only
+}
+
+// A Principal is one user of the bus. Its permissions are derived from what it declares and
+// nothing else (novox/hq ADR 0043), over the three namespaces of design 29 §2: its own, the seats
+// it holds, and the seats it uses.
+type Principal struct {
+	Kind   Kind
+	Node   string
+	Module string
+
+	Emits    []string
+	Consumes []string
+	Serves   []string
+
+	Holds []Seat
+	Uses  []Seat
+	// Watches are seats whose events this principal consumes. Separate from Consumes because a
+	// role's event lives under the seat's namespace and not a module's, and this package cannot tell
+	// a seat's name from a module's by looking at it — whoever resolved the declaration can, and
+	// does (novox/hq ADR 0121).
+	//
+	// **Found by a consumer reading nothing.** The catalogue consumes the build machine's outcome;
+	// with that name read as a module's, its subscription pointed at `mesh.mod.mesh-build-machine.…`,
+	// a namespace no such module owns. Every service started and the graph stayed empty.
+	Watches []Seat
+
+	// Invokes are the tools a person may call, as `<module>.<tool>`; a single `*` is every tool,
+	// for an administrator. Only meaningful for KindPerson.
+	//
+	// **A list, not a role.** A person is not a module and holds no seat: nothing is addressed
+	// to them, nothing is delivered to them, and they have no durable consumer to acknowledge.
+	// What they have is permission to ask.
+	Invokes []string
+
+	// PasswordHash is the bcrypt hash the mesh minted. The plaintext is sealed to the principal
+	// and never appears here: this file is written to a node's disk and read by a server, and a
+	// secret that can be read from a configuration file is a secret with a wider blast radius
+	// than the one it protects (novox/hq design 29 §10).
+	PasswordHash string
+}
+
+// meshSeatsTheControllerUses are the roles the mesh's own flows submit work to. Named rather than
+// derived from the seat set: the controller is not a module and declares no `uses`, so its side of a
+// seat has to be stated, and a list is what makes "which roles does the mesh itself talk to" answerable.
+var meshSeatsTheControllerUses = []string{"mesh-build-machine"}
+
+// enrolmentPrefix is the space every enrolling node's user and inbox live under, so the one place the
+// controller may answer an enrolment is derived from the same constant the user is named from.
+const enrolmentPrefix = "enrol"
+
+// safeSubject refuses anything that would change the meaning of a subject rather than sit inside
+// one. A name carrying a dot would silently widen a permission by adding a token; a name carrying
+// `>` or `*` would widen it to a wildcard, which is the whole authority model gone.
+var safeSubject = regexp.MustCompile(`^[A-Za-z0-9_-]+$`)
+
+// Username is how a principal is named to the server. The node is part of it, so the same module
+// on two machines holds two users, each sealed to its own — the rule management.go already
+// applies, kept.
+func (p Principal) Username() string {
+	switch p.Kind {
+	case KindPerson:
+		return "person." + p.Module
+	case KindModule:
+		return p.Node + "." + p.Module
+	case KindNode:
+		return "node." + p.Node
+	case KindController:
+		return "controller"
+	case KindEnrolment:
+		// Per token, not one shared user. **The inbox is the reason**: with a single `enrolment`
+		// user every machine enrolling at once could read every other's answer, and an answer
+		// carries that node's credentials sealed to it. Design 25 §6 says the inbox a token
+		// derives, and a permission belongs to a user, so the user is per token.
+		//
+		// Named after the node, which **is** the token's id: a token is issued for a node record,
+		// the mesh holds one live claim per record, and the node's name is the one identifier both
+		// sides already have before anything else is agreed. It is also exactly what the other
+		// transport does, where the account is named after the node and the secret is its password.
+		return enrolmentPrefix + "." + p.Node
+	}
+	return ""
+}
+
+// inbox is a principal's own reply space. No user is ever granted a bare `_INBOX.>` (design 25
+// §4): with one account, inbox privacy is the permission list or it is nothing, so each user's
+// inbox is derived from its own identity and its permissions name that prefix and no other.
+func (p Principal) inbox() string { return "_INBOX." + p.Username() + ".>" }
+
+// Permissions is what a principal may publish and subscribe, and whether it may answer.
+type Permissions struct {
+	Publish   []string
+	Subscribe []string
+	// AllowResponses lets a principal reply to a request it received, on the reply subject that
+	// request carried, once.
+	//
+	// **This is what makes scoped inboxes possible at all**, and design 25 §4 did not say it. If
+	// every user's inbox is private to it, a module serving a tool cannot publish the answer —
+	// the answer goes to the *caller's* inbox, which the responder has no permission for. The two
+	// ways out are granting responders `_INBOX.>`, which is precisely the blanket grant §4
+	// refuses, or this: the server itself permits one reply to the subject of a message the user
+	// actually received, and nothing else. The authority is bounded by having been asked.
+	AllowResponses bool
+}
+
+// PermissionsFor derives a principal's authority. Pure, and the only place authority is decided:
+// a permission that cannot be derived from a declaration is a permission nobody can explain.
+func PermissionsFor(p Principal) (Permissions, error) {
+	for _, part := range []struct{ what, value string }{
+		{"node", p.Node}, {"module", p.Module},
+	} {
+		if part.value == "" {
+			continue
+		}
+		if !safeSubject.MatchString(part.value) {
+			return Permissions{}, fmt.Errorf(
+				"%q cannot be part of a subject: a permission is a subject pattern, and this would widen it", part.value)
+		}
+	}
+
+	var pub, sub []string
+	switch p.Kind {
+	case KindController:
+		// The controller owns the mesh's own traffic and the streams. It is the only writer of
+		// stream definitions (design 25 §3), so it alone reaches the JetStream API.
+		pub = []string{"mesh.control.>", "mesh.node.>", "$JS.API.>"}
+		// **And where its consumers deliver.** A push consumer delivers on `_DELIVER.<its name>`,
+		// and a client bound to it subscribes exactly that; the server refused it for every
+		// principal the first time one bound a consumer (2026-09-28). Each kind below is granted
+		// its own consumers' delivery subjects and no other's.
+		sub = []string{"mesh.control.>", "$JS.API.>", "_DELIVER." + ControllerName, "_DELIVER." + ControllerName + ".>"}
+
+		// Work the mesh's own flows submit to a role, and the outcomes they wait on (ADR 0121). A
+		// build is the one today: the controller asks, and reads the answer from the seat's event
+		// like the catalogue does — which is why no holder needs to publish into anybody's inbox.
+		for _, seat := range meshSeatsTheControllerUses {
+			pub = append(pub, "mesh.seat."+seat+".accept.>")
+		}
+		// **And what the mesh says it did** (novox/hq ADR 0134). The control plane states its own
+		// facts under the seat it holds, because a role's events belong to the role and keep their
+		// address while the holder is replaced. Named one by one rather than as a whole namespace:
+		// least authority, and a fact nothing states is authority nobody uses.
+		for _, event := range ControllerStates {
+			pub = append(pub, seatEventSubject(ControllerSeat, event))
+		}
+
+		// Every module's tools: **the control plane is the way in** (novox/hq ADR 0095). A person
+		// or an agent asks through it and every question passes one process where an audit
+		// belongs — so it, alone among principals, may call any tool by name. The first `ask` on
+		// the new bus was refused the publish (2026-09-28).
+		pub = append(pub, "mesh.mod.*.tool.>")
+
+		// The two events it reacts to, and its ack subject on the stream they arrive from
+		// (streams.go). **Each named, not a pattern**: `mesh.mod.*.event.>` would make the
+		// controller a subscriber to every event in the mesh, and its permission list would stop
+		// saying what it is for. The ack grant below is scoped per stream because the controller's
+		// consumer name is the same on both and `$JS.ACK.CONTROL.controller.>` does not cover a
+		// delivery from EVENTS — a consumer that cannot ack has every message redelivered for
+		// ever, refused by the list it already has.
+		sub = append(sub, ControllerFollows...)
+		pub = append(pub, "$JS.ACK.EVENTS."+ControllerName+".>")
+
+		// **Where an enrolment's answer goes**, and `allow_responses` does not cover it. That
+		// permits one reply to the reply subject of a message the user received — and a message a
+		// JetStream consumer delivers has had that field claimed for the consumer's own ack address
+		// (design 25 §2), so the address the controller actually answers is the one the request
+		// carried in its payload, which is not a reply subject as the server understands it.
+		//
+		// Verified against a real server before this line existed: the answer was refused with
+		// "Permissions Violation for Publish to _INBOX.enrol.anchor…", and every enrolment on the
+		// mesh would have timed out while the controller logged success.
+		//
+		// **The enrolment inbox space, not a blanket `_INBOX.>`.** Design 25 §4 refuses that, and
+		// this is not it: nothing but an enrolling node ever subscribes under this prefix, each
+		// scoped to its own token's, so the controller publishing here is the mesh answering
+		// enrolments and can reach nothing else.
+		pub = append(pub, "_INBOX."+enrolmentPrefix+".>")
+
+	case KindPerson:
+		// Tools, and nothing else. Every subject a person may publish is a tool call; a person
+		// who could publish an event would be able to claim a module said something.
+		for _, t := range p.Invokes {
+			if t == "*" {
+				pub = append(pub, "mesh.mod.*.tool.>")
+				continue
+			}
+			module, tool, ok := strings.Cut(t, ".")
+			if !ok {
+				return Permissions{}, fmt.Errorf(
+					"%q does not name a tool: a person invokes <module>.<tool>, or * for every one", t)
+			}
+			pub = append(pub, "mesh.mod."+module+".tool."+tool)
+		}
+
+	case KindEnrolment:
+		// A leaked token is useless for anything but enrolling: it cannot read a declaration, hear
+		// an event, or subscribe any inbox but the one its own token derives (design 25 §6).
+		//
+		// **The inbox was missing and the handshake could not have completed without it.** An
+		// enrolling node publishes its request and waits on an address it states in the payload;
+		// with nothing to subscribe it waits out its timeout against a mesh that answered. Its own
+		// and no wider: `_INBOX.enrol.<node>.>`, so what is sealed to one machine cannot be read by
+		// another enrolling beside it.
+		if p.Node == "" {
+			// Refused rather than composed into `_INBOX.enrol..>`, which is a subject with an empty
+			// token in it — and worse, one every nameless enrolment user would share. A shared
+			// enrolment inbox is one machine able to read the credentials sealed to another.
+			return Permissions{}, errors.New(
+				"an enrolment user names no node, so its inbox would be shared with every other " +
+					"enrolment: a token is issued for a node record, and that record's name is " +
+					"the token's id")
+		}
+		pub = []string{"mesh.control.enrol"}
+		sub = []string{p.inbox()}
+
+	case KindNode:
+		// A host publishes its own node's control traffic and subscribes its own declaration —
+		// and nothing of any other node's.
+		// And binding to its consumer, which asks the server about it (CONSUMER.INFO) — the one
+		// thing the host does that nothing granted. Found the first time a machine dialled a
+		// permissioned server: "this node cannot read its declarations" (2026-09-28). The ack and
+		// the inbox are granted below with every principal's.
+		pub = []string{
+			"mesh.control." + p.Node + ".>",
+			"$JS.API.CONSUMER.INFO.NODES." + p.Node,
+		}
+		sub = []string{"mesh.node." + p.Node + ".declare", "_DELIVER." + p.Node}
+
+	case KindModule:
+		// 1. Its own namespace: it publishes its events there and serves its tools there. Nothing
+		//    else may publish into it, so an event's source is a fact the server enforces rather
+		//    than a claim in the body (design 29 §2).
+		own := "mesh.mod." + p.Module
+		for _, e := range p.Emits {
+			pub = append(pub, own+".event."+e)
+		}
+		// Every tool under its own name, not a list: the tools a module serves are what its code
+		// answers, and a second copy of that list in the manifest would be a second source of
+		// truth for the mesh to keep in step (2026-09-28: every module that served a tool was
+		// refused the subscription, because none had written the list twice). Nothing is given
+		// away — no other principal may subscribe this namespace, and a caller's authority is
+		// still granted per tool, by name, on the publish side.
+		sub = append(sub, own+".tool.>")
+
+		// 2. What it consumes, by the emitter's own subject — an event is addressed to its
+		//    emitter, because the emitter's identity is the meaning (ADR 0118).
+		for _, c := range p.Consumes {
+			subject, err := consumedSubject(c)
+			if err != nil {
+				return Permissions{}, err
+			}
+			sub = append(sub, subject)
+		}
+
+		// 2b. Events of a role it watches, under the seat's own namespace. Subscribe only: watching a
+		//     role is hearing what it announced, not taking part in it.
+		for _, w := range p.Watches {
+			for _, e := range w.Emits {
+				sub = append(sub, seatSubject(w, "event", e))
+			}
+		}
+
+		// 2c. Its own consumer, which it **pulls**: the runtime asks for the next message and is
+		//     answered on its own inbox, so what it needs is to ask about the consumer and to ask it
+		//     for messages — its own consumer's name, and no other's. Pulled rather than pushed
+		//     because that is the one shape a runtime's client binds without creating anything; the
+		//     controller and the hosts are pushed to. Named here rather than through ConsumerFor,
+		//     which asks for these permissions to build the consumer and would ask forever. A
+		//     subject for a consumer that turns out not to exist grants nothing anybody can use.
+		pub = append(pub,
+			"$JS.API.CONSUMER.INFO."+consumerStream(p)+"."+consumerDurable(p),
+			"$JS.API.CONSUMER.MSG.NEXT."+consumerStream(p)+"."+consumerDurable(p))
+
+		// 3. Seats it holds: full participation.
+		for _, s := range p.Holds {
+			// Taking work from the role's queue: the worker consumer it binds (asked about,
+			// delivered on, acknowledged), each on the seat's own stream. The first machine to
+			// take work over the new bus was refused the asking (2026-09-28).
+			worker := "SEAT_" + upperSnake(s.Name) + "_worker"
+			stream := seatStreamName(s.Name)
+			sub = append(sub, "_DELIVER."+worker)
+			pub = append(pub, "$JS.API.CONSUMER.INFO."+stream+"."+worker, "$JS.ACK."+stream+"."+worker+".>")
+			for _, a := range s.Accepts {
+				sub = append(sub, seatSubject(s, "accept", a))
+			}
+			for _, e := range s.Emits {
+				pub = append(pub, seatSubject(s, "event", e))
+			}
+			for _, t := range s.Serves {
+				sub = append(sub, seatSubject(s, "tool", t))
+			}
+		}
+
+		// 4. Seats it uses: publish only, and only the accepts half. A caller cannot subscribe a
+		//    seat's inbound subject and watch other modules' traffic, nor publish its outbound
+		//    events and lie about outcomes (design 29 §2).
+		for _, s := range p.Uses {
+			for _, a := range s.Accepts {
+				pub = append(pub, seatSubject(s, "accept", a))
+			}
+			for _, t := range s.Serves {
+				pub = append(pub, seatSubject(s, "tool", t))
+			}
+		}
+	}
+
+	if p.Kind == KindPerson {
+		// An inbox to hear answers in, and nothing else. No ack subject: a person has no durable
+		// consumer, because nothing is delivered to a person — they ask and are answered.
+		sub = append(sub, p.inbox())
+	}
+
+	if p.Kind == KindModule || p.Kind == KindNode || p.Kind == KindController {
+		// Its own reply space, and nothing wider.
+		sub = append(sub, p.inbox())
+
+		// Acking a JetStream delivery is a publish to that consumer's own ack address — a
+		// different subject from anything the consumer subscribes. Without it every message a
+		// module received would be redelivered forever, refused by the permission list it already
+		// has (design 25 §4). Scoped to this principal's own consumer name, so it can ack its own
+		// deliveries and no other's.
+		pub = append(pub, "$JS.ACK."+consumerStream(p)+"."+consumerDurable(p)+".>")
+	}
+
+	sort.Strings(pub)
+	sort.Strings(sub)
+	return Permissions{
+		Publish:   pub,
+		Subscribe: sub,
+		// A module answers what it was asked — a tool call reaches it on its own namespace, so the
+		// authority is bounded by having been asked — and so does the controller. A node and a
+		// person are never asked anything, and are granted nothing here.
+		AllowResponses: p.Kind == KindModule || p.Kind == KindController,
+	}, nil
+}
+
+// seatSubject places a seat's verb under the kind of traffic it is.
+//
+// **The kind token is load-bearing, not decoration.** A stream is defined by a subject filter, so
+// without it a stream over a seat or a module's namespace would capture that namespace's *tool*
+// traffic too — and a tool call must never be persisted (design 25 §3: tools stay on core NATS).
+// Found while defining the streams: the first draft of design 29 had one namespace per module
+// with no kind, which reads well and cannot be filtered.
+//
+// A seat serving more than its current protocol version carries the version as a token
+// (design 29 §8): the seat stays one role, and v1 and v2 run beside each other until nothing is
+// bound to the old one.
+func seatSubject(s Seat, kind, verb string) string {
+	return "mesh.seat." + s.Name + "." + kind + "." + verb
+}
+
+// consumerStream and consumerDurable are the two halves of a consumer's identity, and they are
+// two functions because conflating them was a real bug.
+//
+// **A durable name may not contain a dot; an ack subject is built from two names that do.** The
+// server acknowledges on `$JS.ACK.<stream>.<consumer>.…`, so a single string "EVENTS.one_audit"
+// reads correctly inside the permission and is rejected as a consumer name — *nats: invalid
+// consumer name*. Caught against a running server, and worth the comment because the shape of
+// the failure if it had not been is the one design 25 §4 warns about: a consumer that cannot ack
+// has every message redelivered forever, and its permission list looks right while it happens.
+//
+// They are derived here, beside the permission that must match them, because two places deriving
+// the same name is how a module ends up unable to ack its own deliveries.
+// consumedSubject is where a consumed event lands, from the local pattern a module declared.
+//
+// **The mesh's wildcards become this transport's** (design 29 §1): `*` is one name on both, and `**`
+// — the rest — is `>` here. A module writes neither transport's spelling, so a manifest stays correct
+// when the wire changes, which is the whole reason names are local.
+//
+// `**` on its own is every event from every module: the emitter is any, the event is anything. An
+// audit logger wants exactly that and says so in one token.
+func consumedSubject(pattern string) (string, error) {
+	if pattern == catalogueTheRest {
+		return "mesh.mod.*.event.>", nil
+	}
+	emitter, event, named := strings.Cut(pattern, ".")
+	if !named || emitter == "" || event == "" {
+		return "", fmt.Errorf(
+			"%q does not name an emitter and an event: a consumed event is <emitter>.<event>, or "+
+				"%q for every event", pattern, catalogueTheRest)
+	}
+	if emitter == catalogueTheRest {
+		return "", fmt.Errorf("%q stands for the rest of a name, so it cannot name the emitter", catalogueTheRest)
+	}
+	// Each name is checked before it becomes a subject: a name carrying a dot would add a token and
+	// silently widen the permission, which is the whole reason safeSubject exists.
+	var out []string
+	for _, part := range strings.Split(event, ".") {
+		switch part {
+		case catalogueTheRest:
+			out = append(out, ">")
+		case "*":
+			out = append(out, "*")
+		default:
+			if !safeSubject.MatchString(part) {
+				return "", fmt.Errorf("%q cannot be part of a subject: it would widen the permission", part)
+			}
+			out = append(out, part)
+		}
+	}
+	if emitter != "*" && !safeSubject.MatchString(emitter) {
+		return "", fmt.Errorf("%q cannot name an emitter: it would widen the permission", emitter)
+	}
+	return "mesh.mod." + emitter + ".event." + strings.Join(out, "."), nil
+}
+
+// catalogueTheRest is the mesh's wildcard for "the rest of a name", duplicated from the catalogue
+// package for the one direction of dependency the build queue's name is duplicated for.
+const catalogueTheRest = "**"
+
+func consumerStream(p Principal) string {
+	switch p.Kind {
+	case KindModule:
+		return "EVENTS"
+	case KindNode:
+		return "NODES"
+	case KindController:
+		return "CONTROL"
+	}
+	return ""
+}
+
+func consumerDurable(p Principal) string {
+	switch p.Kind {
+	case KindModule:
+		return p.Node + "_" + p.Module
+	case KindNode:
+		return p.Node
+	case KindController:
+		return "controller"
+	}
+	return ""
+}
+
+// Server is everything the composed file needs that is not a principal.
+type Server struct {
+	// ClientPort carries TLS itself. There is no plaintext port beside it: a bus reachable
+	// without TLS is one a module can reach without TLS by mistake.
+	ClientPort     int
+	MonitoringPort int
+	TLSCert        string
+	TLSKey         string
+	TLSCA          string
+	// StoreDir is a host directory bind, not a named volume — issue 115 is resolved and converted
+	// four modules away from named volumes; the bus's own data is not the place to bring one back.
+	StoreDir string
+}
+
+// Compose renders the server's whole configuration. The order is stable and the output is
+// deterministic, because the file's digest is what the module's entrypoint watches to decide
+// whether to reload: a composer that reordered a map on each run would signal a reload every time
+// the controller restarted, for a file that had not changed.
+func Compose(s Server, principals []Principal) (string, error) {
+	sorted := append([]Principal(nil), principals...)
+	sort.Slice(sorted, func(i, j int) bool { return sorted[i].Username() < sorted[j].Username() })
+
+	var b strings.Builder
+	b.WriteString("# Composed by the mesh controller. Do not edit: the next composition overwrites it.\n")
+	b.WriteString("# Accounts and permissions are derived from what each module declares and nothing\n")
+	b.WriteString("# else (novox/hq ADR 0043, design 29 §2).\n\n")
+
+	fmt.Fprintf(&b, "port: %d\n", s.ClientPort)
+	fmt.Fprintf(&b, "http: 127.0.0.1:%d\n\n", s.MonitoringPort)
+
+	// **No `verify`, and it said `verify: true` until this configuration was run.** That setting
+	// makes the server demand a *client* certificate, and nothing in the mesh presents one: a host
+	// pins this server's exact certificate and authenticates with the password the mesh minted
+	// (ADR 0004, design 25 §4), and so does a module's runtime. With it on, every connection in the
+	// mesh is refused at the TLS handshake before any password is looked at, and the error —
+	// "client didn't provide a certificate" — reads as a fault in the client.
+	//
+	// TLS is still required: the block is what requires it, and verify only decides whether client
+	// certificates are checked.
+	b.WriteString("tls {\n")
+	fmt.Fprintf(&b, "  cert_file: %q\n", s.TLSCert)
+	fmt.Fprintf(&b, "  key_file: %q\n", s.TLSKey)
+	fmt.Fprintf(&b, "  ca_file: %q\n", s.TLSCA)
+	b.WriteString("}\n\n")
+
+	b.WriteString("jetstream {\n")
+	fmt.Fprintf(&b, "  store_dir: %q\n", s.StoreDir)
+	b.WriteString("}\n\n")
+
+	accounts, err := ComposeAccounts(sorted)
+	if err != nil {
+		return "", err
+	}
+	b.WriteString(accounts)
+	return b.String(), nil
+}
+
+// ComposeAccounts is the accounts block alone — every user, and nothing about the server.
+//
+// **This is the only part of the configuration the mesh writes, and the split is deliberate.** A
+// server's ports, its TLS paths and its store directory are properties of the container the module
+// raises: they live in its image and its mounts, and they change when it does. The controller has no
+// business knowing them, and a controller that did would have to be kept in step with a Dockerfile
+// it never sees. What only the mesh knows is *who may connect*, so that is what it writes, and the
+// module's own configuration includes it.
+//
+// Four things checked against a running server before this shape was committed to: a user in an
+// included file authenticates; an unknown user is refused, so the include is the whole authority
+// rather than an addition to something; a publish outside a user's grant is refused; and rewriting
+// this file alone and signalling a reload makes a new user appear **without dropping the connection
+// the mesh already has** — which is what makes every later account, permission or person change cost
+// nothing (task 1.2's payoff).
+func ComposeAccounts(principals []Principal) (string, error) {
+	sorted := append([]Principal(nil), principals...)
+	sort.Slice(sorted, func(i, j int) bool { return sorted[i].Username() < sorted[j].Username() })
+
+	var b strings.Builder
+	b.WriteString("# The mesh's users, composed by the controller. Do not edit: the next\n")
+	b.WriteString("# composition overwrites it. Permissions are derived from what each module\n")
+	b.WriteString("# declares and nothing else (novox/hq ADR 0043, design 29 §2).\n\n")
+
+	// One account for the mesh: accounts in NATS isolate subject spaces entirely, and the mesh is
+	// one space (design 25 §4). The cost of that — that permissions are the only isolation — is
+	// paid in the scoping of every inbox and every ack subject.
+	// JetStream is enabled per account once accounts exist at all: with only the global block set,
+	// a user in MESH is told "JetStream not enabled for account" the first time it binds a
+	// consumer, which is the first thing every host does (2026-09-28).
+	b.WriteString("accounts {\n  MESH {\n    jetstream: enabled\n    users = [\n")
+	for _, p := range sorted {
+		perms, err := PermissionsFor(p)
+		if err != nil {
+			return "", err
+		}
+		if p.PasswordHash == "" {
+			return "", fmt.Errorf("%s has no password hash: a user without one is a user anybody is", p.Username())
+		}
+		fmt.Fprintf(&b, "      { user: %q, password: %q, permissions: {\n", p.Username(), p.PasswordHash)
+		fmt.Fprintf(&b, "        publish: { allow: [%s] }\n", quoted(perms.Publish))
+		fmt.Fprintf(&b, "        subscribe: { allow: [%s] }\n", quoted(perms.Subscribe))
+		if perms.AllowResponses {
+			b.WriteString("        allow_responses: { max: 1, ttl: \"1m\" }\n")
+		}
+		b.WriteString("      } }\n")
+	}
+	b.WriteString("    ]\n  }\n}\n")
+	return b.String(), nil
+}
+
+func quoted(values []string) string {
+	if len(values) == 0 {
+		return ""
+	}
+	out := make([]string, len(values))
+	for i, v := range values {
+		out[i] = fmt.Sprintf("%q", v)
+	}
+	return strings.Join(out, ", ")
+}
@@ -0,0 +1,49 @@
+package broker
+
+import (
+	"flag"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+var update = flag.Bool("update", false, "rewrite the golden composition")
+
+// The composed file is the mesh's whole authority model, so a change to it should be visible in a
+// review rather than inferred from a diff of Go. The fixture is also the exact text checked
+// against the real server's parser (`nats-server -t`), which is what says this syntax is the
+// server's and not one we invented.
+func TestTheComposedConfigMatchesTheGolden(t *testing.T) {
+	seat := Seat{Name: "telegram-sender", Accepts: []string{"send"}, Emits: []string{"delivered", "failed"}}
+	got, err := Compose(
+		Server{ClientPort: 4222, MonitoringPort: 8222, StoreDir: "/data",
+			TLSCert: "/tls/tls.crt", TLSKey: "/tls/tls.key", TLSCA: "/tls/ca.crt"},
+		[]Principal{
+			{Kind: KindController, PasswordHash: "$2a$11$cccccccccccccccccccccc"},
+			{Kind: KindEnrolment, Node: "one", PasswordHash: "$2a$11$eeeeeeeeeeeeeeeeeeeeee"},
+			{Kind: KindNode, Node: "one", PasswordHash: "$2a$11$nnnnnnnnnnnnnnnnnnnnnn"},
+			{Kind: KindModule, Node: "one", Module: "telegram", Holds: []Seat{seat},
+				Serves: []string{"status"}, PasswordHash: "$2a$11$tttttttttttttttttttttt"},
+			{Kind: KindModule, Node: "two", Module: "shop", Uses: []Seat{seat},
+				Emits: []string{"order.placed"}, PasswordHash: "$2a$11$ssssssssssssssssssssss"},
+			{Kind: KindModule, Node: "two", Module: "audit",
+				Consumes: []string{"shop.order.placed"}, PasswordHash: "$2a$11$aaaaaaaaaaaaaaaaaaaaaa"},
+		})
+	if err != nil {
+		t.Fatal(err)
+	}
+	golden := filepath.Join("testdata", "composed.conf")
+	if *update {
+		if err := os.WriteFile(golden, []byte(got), 0o644); err != nil {
+			t.Fatal(err)
+		}
+		return
+	}
+	want, err := os.ReadFile(golden)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != string(want) {
+		t.Errorf("composition changed; re-run with -update and read the diff:\n%s", got)
+	}
+}
@@ -0,0 +1,361 @@
+package broker
+
+import (
+	"slices"
+	"strings"
+	"testing"
+)
+
+func has(t *testing.T, subjects []string, want string) {
+	t.Helper()
+	for _, s := range subjects {
+		if s == want {
+			return
+		}
+	}
+	t.Fatalf("expected %q among %v", want, subjects)
+}
+
+func hasNot(t *testing.T, subjects []string, unwanted string) {
+	t.Helper()
+	for _, s := range subjects {
+		if s == unwanted {
+			t.Fatalf("did not expect %q among %v", unwanted, subjects)
+		}
+	}
+}
+
+// A module's authority comes from its declaration and nothing else (novox/hq ADR 0043).
+func TestAModulePublishesOnlyWhatItEmits(t *testing.T) {
+	p := Principal{Kind: KindModule, Node: "one", Module: "billing",
+		Emits: []string{"order.placed"}, PasswordHash: "x"}
+	perms, err := PermissionsFor(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	has(t, perms.Publish, "mesh.mod.billing.event.order.placed")
+	hasNot(t, perms.Publish, "mesh.mod.billing.>")
+	hasNot(t, perms.Publish, "mesh.mod.shipping.event.order.placed")
+}
+
+// The gap AMQP left open — an emitter granted the events exchange whole — is closed by per-subject
+// permissions. A module cannot publish under another module's name.
+func TestAModuleCannotPublishUnderAnothersName(t *testing.T) {
+	perms, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "billing",
+		Emits: []string{"order.placed"}, PasswordHash: "x"})
+	for _, p := range perms.Publish {
+		if strings.HasPrefix(p, "mesh.mod.") && !strings.HasPrefix(p, "mesh.mod.billing.") {
+			t.Fatalf("billing may publish %q, which is not its own namespace", p)
+		}
+	}
+}
+
+// A caller of a seat may publish what the seat accepts, and nothing else of it: not its outbound
+// events, and not a subscription to its inbound queue (design 29 §2).
+func TestUsingASeatIsPublishOnlyAndInboundOnly(t *testing.T) {
+	seat := Seat{Name: "telegram-sender", Accepts: []string{"send"}, Emits: []string{"delivered", "failed"}}
+	perms, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "shop",
+		Uses: []Seat{seat}, PasswordHash: "x"})
+	has(t, perms.Publish, "mesh.seat.telegram-sender.accept.send")
+	hasNot(t, perms.Publish, "mesh.seat.telegram-sender.event.delivered")
+	hasNot(t, perms.Subscribe, "mesh.seat.telegram-sender.accept.send")
+}
+
+// The holder is the mirror image: it consumes what the seat accepts and publishes what it emits.
+func TestHoldingASeatIsTheMirrorOfUsingIt(t *testing.T) {
+	seat := Seat{Name: "telegram-sender", Accepts: []string{"send"}, Emits: []string{"delivered", "failed"}}
+	perms, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "telegram",
+		Holds: []Seat{seat}, PasswordHash: "x"})
+	has(t, perms.Subscribe, "mesh.seat.telegram-sender.accept.send")
+	has(t, perms.Publish, "mesh.seat.telegram-sender.event.delivered")
+	hasNot(t, perms.Publish, "mesh.seat.telegram-sender.accept.send")
+}
+
+// Without an ack permission a durable consumer never really consumes: every message it receives is
+// redelivered forever, refused by the permission list it already has (design 25 §4).
+func TestAModuleMayAckItsOwnDeliveriesAndNoOthers(t *testing.T) {
+	perms, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "billing",
+		Consumes: []string{"shop.order.placed"}, PasswordHash: "x"})
+	has(t, perms.Publish, "$JS.ACK.EVENTS.one_billing.>")
+	hasNot(t, perms.Publish, "$JS.ACK.>")
+	hasNot(t, perms.Publish, "$JS.ACK.EVENTS.one_shop.>")
+}
+
+// With one account, inbox privacy is the permission list or it is nothing.
+func TestAnInboxIsScopedToItsOwner(t *testing.T) {
+	perms, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "billing", PasswordHash: "x"})
+	has(t, perms.Subscribe, "_INBOX.one.billing.>")
+	hasNot(t, perms.Subscribe, "_INBOX.>")
+	hasNot(t, perms.Subscribe, "_INBOX.one.shop.>")
+}
+
+// A responder answers on the caller's inbox, which it has no permission for. allow_responses is
+// what makes a scoped inbox workable at all — the authority is bounded by having been asked. A
+// module is asked on its own namespace and may answer; a node and a person are never asked.
+func TestOnlyWhatCanBeAskedMayAnswer(t *testing.T) {
+	module, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "audit",
+		Consumes: []string{"shop.order.placed"}, PasswordHash: "x"})
+	if !module.AllowResponses {
+		t.Fatal("a module cannot answer a tool call on its own namespace")
+	}
+	node, _ := PermissionsFor(Principal{Kind: KindNode, Node: "one", PasswordHash: "x"})
+	if node.AllowResponses {
+		t.Fatal("a node was granted the right to answer, and nothing asks a node anything")
+	}
+}
+
+// A module serves every tool under its own name, and no other module's.
+func TestAModuleServesItsOwnNamespaceAndNoOthers(t *testing.T) {
+	p, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "gitea", PasswordHash: "x"})
+	if !slices.Contains(p.Subscribe, "mesh.mod.gitea.tool.>") {
+		t.Fatalf("a module may not serve its own tools: %v", p.Subscribe)
+	}
+	for _, s := range p.Subscribe {
+		if strings.HasPrefix(s, "mesh.mod.") && !strings.HasPrefix(s, "mesh.mod.gitea.") {
+			t.Fatalf("a module may subscribe another's namespace: %s", s)
+		}
+	}
+}
+
+// A host reaches its own node's control traffic and its own declaration, and nothing of any
+// other node's.
+func TestAHostIsConfinedToItsOwnNode(t *testing.T) {
+	perms, _ := PermissionsFor(Principal{Kind: KindNode, Node: "one", PasswordHash: "x"})
+	has(t, perms.Publish, "mesh.control.one.>")
+	has(t, perms.Subscribe, "mesh.node.one.declare")
+	hasNot(t, perms.Subscribe, "mesh.node.two.declare")
+	hasNot(t, perms.Subscribe, "mesh.node.>")
+}
+
+// A leaked enrolment token is useless for anything but enrolling (design 25 §6).
+func TestTheEnrolmentUserCanOnlyEnrol(t *testing.T) {
+	perms, err := PermissionsFor(Principal{Kind: KindEnrolment, Node: "anchor", PasswordHash: "x"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(perms.Publish) != 1 || perms.Publish[0] != "mesh.control.enrol" {
+		t.Fatalf("enrolment may publish %v", perms.Publish)
+	}
+	// Its own inbox and nothing else. **Nothing else** is the point: no declaration, no event, and
+	// no other machine's answer — and the inbox itself is needed, because a node that cannot
+	// subscribe one waits out its timeout against a mesh that answered.
+	if len(perms.Subscribe) != 1 || perms.Subscribe[0] != "_INBOX.enrol.anchor.>" {
+		t.Fatalf("enrolment may subscribe %v, which is not its own inbox alone", perms.Subscribe)
+	}
+}
+
+// An enrolment user that names no node is refused: its inbox would be an empty subject token, and
+// one that every nameless enrolment user shared — which is one machine reading the credentials
+// sealed to another.
+func TestAnEnrolmentUserWithoutANodeIsRefused(t *testing.T) {
+	if _, err := PermissionsFor(Principal{Kind: KindEnrolment, PasswordHash: "x"}); err == nil {
+		t.Fatal("an enrolment user with no node was composed, so its inbox is shared")
+	}
+}
+
+// A name that would widen a permission is refused rather than quietly stretching one.
+func TestANameThatWouldWidenAPermissionIsRefused(t *testing.T) {
+	for _, bad := range []string{"bill.ing", "billing.>", "*", "bil>ling"} {
+		if _, err := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: bad, PasswordHash: "x"}); err == nil {
+			t.Fatalf("%q was accepted as part of a subject", bad)
+		}
+	}
+}
+
+// The entrypoint reloads on the file's digest changing, so an unchanged mesh must compose an
+// identical file — otherwise every controller restart signals a reload of the whole bus.
+func TestComposingTwiceGivesTheSameBytes(t *testing.T) {
+	s := Server{ClientPort: 4222, MonitoringPort: 8222, StoreDir: "/data",
+		TLSCert: "/tls/tls.crt", TLSKey: "/tls/tls.key", TLSCA: "/tls/ca.crt"}
+	ps := []Principal{
+		{Kind: KindModule, Node: "two", Module: "shop", Emits: []string{"order.placed"}, PasswordHash: "b"},
+		{Kind: KindController, PasswordHash: "c"},
+		{Kind: KindModule, Node: "one", Module: "billing", Consumes: []string{"shop.order.placed"}, PasswordHash: "a"},
+	}
+	first, err := Compose(s, ps)
+	if err != nil {
+		t.Fatal(err)
+	}
+	shuffled := []Principal{ps[2], ps[0], ps[1]}
+	second, err := Compose(s, shuffled)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if first != second {
+		t.Fatal("composition is order-dependent; every controller restart would reload the bus")
+	}
+}
+
+// A user without a password is a user anybody is.
+func TestAUserWithoutAPasswordIsRefused(t *testing.T) {
+	_, err := Compose(Server{ClientPort: 4222}, []Principal{{Kind: KindController}})
+	if err == nil {
+		t.Fatal("composed a user with no password hash")
+	}
+}
+
+// A person reaches the mesh's tools from a workstation (design 25 §7). Their authority is a list
+// of tools and nothing else.
+func TestAPersonMayAskOnlyTheToolsTheyWereGiven(t *testing.T) {
+	perms, err := PermissionsFor(Principal{Kind: KindPerson, Module: "jo",
+		Invokes: []string{"shop.price", "telegram.status"}, PasswordHash: "x"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	has(t, perms.Publish, "mesh.mod.shop.tool.price")
+	has(t, perms.Publish, "mesh.mod.telegram.tool.status")
+	hasNot(t, perms.Publish, "mesh.mod.shop.tool.refund")
+	hasNot(t, perms.Publish, "mesh.mod.*.tool.>")
+}
+
+// An administrator gets every tool, which is a different grant and looks like one.
+func TestAnAdministratorMayAskAnyTool(t *testing.T) {
+	perms, _ := PermissionsFor(Principal{Kind: KindPerson, Module: "jo",
+		Invokes: []string{"*"}, PasswordHash: "x"})
+	has(t, perms.Publish, "mesh.mod.*.tool.>")
+}
+
+// **Nothing but tools.** A person who could publish an event would be able to claim a module
+// said something; one who could publish control traffic would be a second controller.
+func TestAPersonReachesNothingButTools(t *testing.T) {
+	perms, _ := PermissionsFor(Principal{Kind: KindPerson, Module: "jo",
+		Invokes: []string{"*"}, PasswordHash: "x"})
+	for _, p := range perms.Publish {
+		if !strings.Contains(p, ".tool.") {
+			t.Errorf("a person may publish %q, which is not a tool call", p)
+		}
+	}
+	for _, s := range perms.Subscribe {
+		if !strings.HasPrefix(s, "_INBOX.person.") {
+			t.Errorf("a person may subscribe %q; only their own inbox should be reachable", s)
+		}
+	}
+}
+
+// A person has no durable consumer, because nothing is delivered to a person — so no ack
+// subject, and an ack permission would be authority over something that does not exist.
+func TestAPersonHasNoAckSubject(t *testing.T) {
+	perms, _ := PermissionsFor(Principal{Kind: KindPerson, Module: "jo",
+		Invokes: []string{"*"}, PasswordHash: "x"})
+	for _, p := range perms.Publish {
+		if strings.HasPrefix(p, "$JS.ACK") {
+			t.Errorf("a person was granted %q, and has no consumer to acknowledge", p)
+		}
+	}
+}
+
+// A person asks and is answered; they never answer. allow_responses would let a person reply to
+// a request — which, on a bus where anyone may serve a tool, is somebody impersonating a module.
+func TestAPersonMayNotAnswer(t *testing.T) {
+	perms, _ := PermissionsFor(Principal{Kind: KindPerson, Module: "jo",
+		Invokes: []string{"*"}, PasswordHash: "x"})
+	if perms.AllowResponses {
+		t.Fatal("a person may answer a request, which is impersonating a module")
+	}
+}
+
+// Two people do not share an inbox, or one would read the other's answers.
+func TestTwoPeopleDoNotShareAnInbox(t *testing.T) {
+	a, _ := PermissionsFor(Principal{Kind: KindPerson, Module: "jo", Invokes: []string{"*"}, PasswordHash: "x"})
+	b, _ := PermissionsFor(Principal{Kind: KindPerson, Module: "sam", Invokes: []string{"*"}, PasswordHash: "x"})
+	if a.Subscribe[0] == b.Subscribe[0] {
+		t.Fatalf("both read %s", a.Subscribe[0])
+	}
+}
+
+// A malformed grant is refused rather than widened into something that happens to parse.
+func TestAToolGrantThatNamesNoToolIsRefused(t *testing.T) {
+	if _, err := PermissionsFor(Principal{Kind: KindPerson, Module: "jo",
+		Invokes: []string{"shop"}, PasswordHash: "x"}); err == nil {
+		t.Fatal("a grant naming a module but no tool was accepted")
+	}
+}
+
+// The controller can answer an enrolment, and reach no other inbox.
+//
+// **`allow_responses` does not cover this and that is the trap.** It permits one reply to the reply
+// subject of a message the user received — and a message a JetStream consumer delivers has had that
+// field claimed for the consumer's own ack address, so the address the controller actually answers is
+// the one the request carried in its payload, which the server does not recognise as a reply subject
+// at all.
+//
+// Found against a real server, after a live test on an *unpermissioned* one had passed: every
+// enrolment on the mesh would have timed out while the controller logged success.
+func TestTheControllerCanAnswerAnEnrolmentAndReachNoOtherInbox(t *testing.T) {
+	ctl, err := PermissionsFor(Principal{Kind: KindController, PasswordHash: "x"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	enrolling, err := PermissionsFor(Principal{Kind: KindEnrolment, Node: "anchor", PasswordHash: "x"})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Whatever the enrolling node waits on, the controller must be able to publish to.
+	if len(enrolling.Subscribe) != 1 {
+		t.Fatalf("an enrolling node subscribes %v, and this test knows only how to check one",
+			enrolling.Subscribe)
+	}
+	waitsOn := enrolling.Subscribe[0]
+	if !covers(ctl.Publish, waitsOn) {
+		t.Fatalf("the controller may publish %v, none of which reaches %s — so every enrolment on "+
+			"the mesh times out while the controller logs success", ctl.Publish, waitsOn)
+	}
+
+	// And nothing wider. A node's own inbox and a module's are not the controller's to write into:
+	// that is the blanket grant design 25 §4 refuses.
+	for _, other := range []string{"_INBOX.node.anchor.x", "_INBOX.one.shop.x", "_INBOX.person.ada.x"} {
+		if covers(ctl.Publish, other) {
+			t.Errorf("the controller can publish to %s, which is an inbox privacy the permission "+
+				"list is the only thing protecting", other)
+		}
+	}
+}
+
+// covers says whether any granted subject pattern admits one concrete subject, with NATS's own
+// wildcard meanings: `*` is one token, `>` is the rest.
+func covers(granted []string, subject string) bool {
+	want := strings.Split(subject, ".")
+	for _, pattern := range granted {
+		if admits(strings.Split(pattern, "."), want) {
+			return true
+		}
+	}
+	return false
+}
+
+func admits(pattern, subject []string) bool {
+	for i, token := range pattern {
+		if token == ">" {
+			return i < len(subject)
+		}
+		if i >= len(subject) {
+			return false
+		}
+		if token != "*" && token != subject[i] {
+			return false
+		}
+	}
+	return len(pattern) == len(subject)
+}
+
+// A module pulls its own consumer — asks about it, asks it for messages — and no other module's.
+func TestAModulePullsItsOwnConsumerAndNoOthers(t *testing.T) {
+	p, _ := PermissionsFor(Principal{Kind: KindModule, Node: "one", Module: "audit",
+		Consumes: []string{"shop.order.placed"}, PasswordHash: "x"})
+	for _, want := range []string{"$JS.API.CONSUMER.INFO.EVENTS.one_audit", "$JS.API.CONSUMER.MSG.NEXT.EVENTS.one_audit"} {
+		if !slices.Contains(p.Publish, want) {
+			t.Errorf("a module cannot bind its own consumer: %v lacks %s", p.Publish, want)
+		}
+	}
+	for _, s := range p.Publish {
+		if strings.Contains(s, "CONSUMER.") && !strings.HasSuffix(s, ".one_audit") {
+			t.Errorf("a module may reach another consumer: %s", s)
+		}
+	}
+	for _, s := range p.Subscribe {
+		if strings.HasPrefix(s, "_DELIVER.") {
+			t.Errorf("a module is granted a push delivery it never binds: %s", s)
+		}
+	}
+}
@@ -0,0 +1,83 @@
+package broker
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/novox/mesh-controller/internal/envfile"
+)
+
+// Whether this mesh's own traffic is on the bus being built.
+//
+// **One switch, read in one place** (novox/hq ADR 0116 step 5). Every seam the bus change went
+// behind ships both implementations, and until the rollout every one of them chooses the bus the
+// mesh runs on today. This is what the rollout flips, and it is deliberately a single fact rather
+// than a fact per component: a controller whose outbound is on one bus and whose inbound is on the
+// other is a mesh that hears nothing, and no test of either half would catch it.
+
+// NATSVar is where the controller finds the bus being built. Unset is the ordinary case and means
+// the mesh runs on the bus it has always run on.
+const NATSVar = "MESH_BUS_NATS"
+
+// OnNATS is the address of the bus being built, and whether the mesh is on it.
+//
+// Read from the node's own settings rather than baked in, for the reason the broker's address is
+// (novox/hq 04-ISSUES/102): an address recorded once does not follow a node's ports.
+func OnNATS() (address string, on bool, err error) {
+	address, err = envfile.Placed(NATSVar)
+	if err != nil {
+		return "", false, err
+	}
+	address = strings.TrimSpace(address)
+	if address == "" {
+		return "", false, nil
+	}
+	return address, true, nil
+}
+
+// CredentialIn reads the user and password out of a bus address, and the address without them.
+//
+// The controller's own credential arrives in its address, the way the old bus's does. Split out so the
+// controller can record a hash of what it is actually using: its user is created by the installer at a
+// bootstrap password, before the controller exists to mint one, and a composition that left itself out
+// would produce a bus the writer cannot connect to.
+func CredentialIn(address string) (user, password, bare string) {
+	at := strings.LastIndex(address, "@")
+	if at < 0 {
+		return "", "", address
+	}
+	scheme := ""
+	rest := address[:at]
+	if i := strings.Index(rest, "://"); i >= 0 {
+		scheme, rest = rest[:i+3], rest[i+3:]
+	}
+	user, password, _ = strings.Cut(rest, ":")
+	return user, password, scheme + address[at+1:]
+}
+
+// BareAddress is a bus address with any credential stripped, for something that only needs to know
+// whether a server is answering there.
+func BareAddress(address string) string {
+	_, _, bare := CredentialIn(address)
+	if bare == "" {
+		return address
+	}
+	if strings.Contains(bare, "://") {
+		return bare
+	}
+	return "nats://" + bare
+}
+
+// BusAddress is where the mesh's bus is, with this process's credential, and refuses to be empty:
+// there is one bus, and a control plane without it can hold records and answer nothing (novox/hq
+// ADR 0131, design 28 task 5.5).
+func BusAddress() (string, error) {
+	address, _, err := OnNATS()
+	if err != nil {
+		return "", err
+	}
+	if address == "" {
+		return "", fmt.Errorf("this control plane has no %s, so it cannot reach the mesh's bus", NATSVar)
+	}
+	return address, nil
+}
@@ -0,0 +1,28 @@
+package broker
+
+import (
+	"testing"
+)
+
+// Which bus the mesh is on is one fact, and being told about both is refused.
+//
+
+// The controller's own credential arrives in its address, and has to be readable out of it — its user
+// is created by the installer at a bootstrap password, before the controller exists to mint one.
+func TestACredentialIsReadOutOfABusAddress(t *testing.T) {
+	for _, c := range []struct{ in, user, password, bare string }{
+		{"nats://controller:secret@127.0.0.1:4222", "controller", "secret", "nats://127.0.0.1:4222"},
+		{"controller:secret@127.0.0.1:4222", "controller", "secret", "127.0.0.1:4222"},
+		{"nats://127.0.0.1:4222", "", "", "nats://127.0.0.1:4222"},
+		{"127.0.0.1:4222", "", "", "127.0.0.1:4222"},
+		// A password containing an at-sign: split on the last one, or the address becomes part of the
+		// credential and the connection goes somewhere nobody named.
+		{"nats://controller:a@b@127.0.0.1:4222", "controller", "a@b", "nats://127.0.0.1:4222"},
+	} {
+		user, password, bare := CredentialIn(c.in)
+		if user != c.user || password != c.password || bare != c.bare {
+			t.Errorf("%q read as %q/%q at %q; wanted %q/%q at %q",
+				c.in, user, password, bare, c.user, c.password, c.bare)
+		}
+	}
+}
@@ -0,0 +1,73 @@
+package broker
+
+import "fmt"
+
+// Bringing the bus's own objects into being, in the one order that works.
+//
+// **Asserted on every start rather than created once at genesis.** A stream somebody deleted, a mesh
+// raised from a restored backup, or a bus whose data directory was replaced all have records and no
+// objects — and a node whose consumer is missing hears nothing while everything else about it looks
+// correct. Idempotence is the whole requirement, and the parts are already idempotent; this is the
+// order they have to be asked in.
+
+// Raiser is everything asserting the bus's objects needs of a connection to it.
+type Raiser interface {
+	Asserter
+	Ensurer
+}
+
+// Raise asserts the mesh's streams, the controller's own consumers, and one consumer per node.
+//
+// **The order is not a preference.** A consumer on a stream that does not exist is refused, and the
+// refusal names the stream rather than the order — so somebody reading it goes looking for a deleted
+// stream instead of a reversed pair of lines. Nodes last, because the one a node reads lives on a
+// stream the mesh's own set defines.
+func Raise(r Raiser, nodes []string) error {
+	if err := AssertMeshStreams(r); err != nil {
+		return err
+	}
+	if err := AssertMeshConsumers(r); err != nil {
+		return err
+	}
+	if err := AssertNodeConsumers(r, nodes); err != nil {
+		return err
+	}
+	return nil
+}
+
+// RaiseSeats asserts one work queue per declared seat, and the worker of whoever holds it.
+//
+// Separate from Raise because it is answered by a different question: the mesh's own objects exist
+// because the mesh does, and a seat's exist because a module declaring one was registered. Kept
+// beside it so the order is visible — a holder's worker needs the seat's stream, and a seat's stream
+// needs nothing.
+func RaiseSeats(r Raiser, seats []DeclaredSeat, holders map[string]Holder) error {
+	for _, s := range SeatStreams(seats) {
+		if err := r.EnsureStream(s); err != nil {
+			return fmt.Errorf("asserting the work queue for %s: %w", s.Name, err)
+		}
+	}
+	for _, s := range seats {
+		h, held := holders[s.Name]
+		if !held {
+			// **The stream exists and the consumer does not, on purpose.** Work queues until a
+			// holder appears, so installing the module a week after something started sending to it
+			// flushes the backlog instead of having lost it.
+			continue
+		}
+		c, needed := HolderConsumerFor(h.Node, h.Module, s)
+		if !needed {
+			continue
+		}
+		if err := r.EnsureConsumer(c); err != nil {
+			return fmt.Errorf("asserting how %s on %s works %s: %w", h.Module, h.Node, s.Name, err)
+		}
+	}
+	return nil
+}
+
+// Holder is which module on which machine holds a seat.
+type Holder struct {
+	Node   string
+	Module string
+}
@@ -0,0 +1,196 @@
+package broker
+
+import (
+	"os"
+	"testing"
+
+	"github.com/nats-io/nats.go"
+)
+
+// Raising the bus's objects against a real server.
+//
+// The pure tests above say what is asked for and in what order. Only a server can say whether it
+// accepts them — and two of these are claims about the server's own behaviour that nothing else
+// could answer: that asserting twice changes nothing, and that a consumer really is bound to the one
+// subject its node is allowed to read.
+//
+//	docker run -d --rm --name t -p 14227:4222 nats:2.10-alpine -js
+//	MESH_TEST_NATS=nats://127.0.0.1:14227 go test ./internal/broker/ -run TestRaising
+
+func aLiveBus(t *testing.T) *JetStream {
+	t.Helper()
+	url := os.Getenv("MESH_TEST_NATS")
+	if url == "" {
+		t.Skip("MESH_TEST_NATS unset")
+	}
+	js, err := Dial(url)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(js.Close)
+	// **Nothing is deleted here, deliberately.** These objects are the mesh's own and every live
+	// test in every package shares one server: a test that deleted a stream to get a clean slate
+	// took it out from under whatever was running beside it, and the failure landed in the other
+	// test as "stream not found" — which reads as a bug in the code under test. Raise is idempotent
+	// by requirement, so asserting against whatever is already there is both safe and the realistic
+	// case.
+	return js
+}
+
+// Every object the mesh's own traffic needs, accepted by a real server, and asserting again changes
+// nothing — which is the whole requirement, because this runs on every start.
+func TestRaisingTheBusIsAcceptedAndIdempotent(t *testing.T) {
+	js := aLiveBus(t)
+
+	if err := Raise(js, []string{"anchor", "laptop"}); err != nil {
+		t.Fatalf("a real server refused the mesh's own objects: %v", err)
+	}
+	// Twice, with nothing in between. A start that failed the second time is a controller that
+	// cannot restart.
+	if err := Raise(js, []string{"anchor", "laptop"}); err != nil {
+		t.Fatalf("asserting the bus's objects a second time failed, so a restart would: %v", err)
+	}
+	// And again with a machine that was not there before, which is what enrolling one is.
+	if err := Raise(js, []string{"anchor", "laptop", "workstation"}); err != nil {
+		t.Fatalf("a machine joining an already-raised bus was refused: %v", err)
+	}
+
+	for _, s := range MeshStreams() {
+		if _, err := js.Context().StreamInfo(s.Name); err != nil {
+			t.Errorf("stream %s is not there: %v", s.Name, err)
+		}
+	}
+	for _, c := range MeshConsumers() {
+		if _, err := js.Context().ConsumerInfo(c.Stream, c.Name); err != nil {
+			t.Errorf("the controller's consumer on %s is not there: %v", c.Stream, err)
+		}
+	}
+	for _, node := range []string{"anchor", "laptop", "workstation"} {
+		info, err := js.Context().ConsumerInfo("NODES", node)
+		if err != nil {
+			t.Errorf("%s has no way to hear its declaration: %v", node, err)
+			continue
+		}
+		// **Its own subject and no other node's.** A consumer filtered on anything wider is a node
+		// reading another machine's declaration, and its own ack grant would not cover it either.
+		if info.Config.FilterSubject != "mesh.node."+node+".declare" {
+			t.Errorf("%s's consumer reads %q", node, info.Config.FilterSubject)
+		}
+		if info.Config.AckPolicy != nats.AckExplicitPolicy {
+			t.Errorf("%s's consumer acknowledges on delivery, so a declaration it died applying is "+
+				"never sent again", node)
+		}
+	}
+}
+
+// The store window needs unlimited redelivery on CONTROL: the bound belongs to the controller, and a
+// server that dead-lettered first would discard the push the stream exists to protect.
+func TestTheControlConsumerDoesNotDeadLetterBeforeTheControllerGivesUp(t *testing.T) {
+	js := aLiveBus(t)
+	if err := Raise(js, nil); err != nil {
+		t.Fatal(err)
+	}
+	info, err := js.Context().ConsumerInfo("CONTROL", ControllerName)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if info.Config.MaxDeliver > 0 {
+		t.Fatalf("max-deliver is %d: a push held through a store restart would be dead-lettered "+
+			"before the controller finished deciding about it", info.Config.MaxDeliver)
+	}
+}
+
+// A role's work queue exists before anybody holds it, against a real server.
+//
+// **The queue before the holder is the point** (novox/hq ADR 0121): work queues until somebody arrives
+// to do it, so assigning a build machine a week after something started asking for builds flushes the
+// backlog instead of having lost it. A stream created at assignment would make "the holder is not here
+// yet" mean "your requests are gone".
+func TestRaisingAMeshRolesWorkQueue(t *testing.T) {
+	js := aLiveBus(t)
+	seats := []DeclaredSeat{{Name: "mesh-build-machine", Accepts: []string{"build"},
+		Emits: []string{"built"}}}
+	t.Cleanup(func() { _ = js.Context().DeleteStream("SEAT_MESH_BUILD_MACHINE") })
+
+	if err := RaiseSeats(js, seats, nil); err != nil {
+		t.Fatalf("a real server refused a role's work queue: %v", err)
+	}
+	info, err := js.Context().StreamInfo("SEAT_MESH_BUILD_MACHINE")
+	if err != nil {
+		t.Fatalf("the role has no work queue: %v", err)
+	}
+	if info.Config.Retention != nats.WorkQueuePolicy {
+		t.Errorf("the queue retains as %v: work a holder took must leave it, or the next holder does "+
+			"it again", info.Config.Retention)
+	}
+	if len(info.Config.Subjects) != 1 || info.Config.Subjects[0] != "mesh.seat.mesh-build-machine.accept.>" {
+		t.Errorf("it carries %v rather than the role's own inbound subjects", info.Config.Subjects)
+	}
+	// Nobody holds it, so there is no worker — and asserting again changes nothing, because this runs
+	// on every start.
+	if err := RaiseSeats(js, seats, nil); err != nil {
+		t.Fatalf("asserting a role's queue a second time failed, so a restart would: %v", err)
+	}
+
+	// And once somebody holds it, the worker appears on that same queue.
+	if err := RaiseSeats(js, seats, map[string]Holder{
+		"mesh-build-machine": {Node: "anchor", Module: "builder"},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := js.Context().ConsumerInfo("SEAT_MESH_BUILD_MACHINE",
+		"SEAT_MESH_BUILD_MACHINE_worker"); err != nil {
+		t.Fatalf("the holder got no worker on the role's queue: %v", err)
+	}
+}
+
+// **A consumer created after the fact still sees what came before it**, which is why the mesh needs no
+// catch-up at all on this bus (novox/hq 04-ISSUES/050).
+//
+// On the bus the mesh runs on today a queue receives only what is published after it is bound, so
+// everything built before the catalogue existed was announced to nobody — and on a fresh mesh that is
+// always the foundation, because those are the things the catalogue needed in order to exist. A whole
+// mechanism was built for it: the catalogue asks, the controller re-publishes.
+//
+// A stream is a log and a consumer is a position in it. A consumer created later starts at the
+// beginning by default, so the builds are simply there. Asked of a real server rather than assumed,
+// because the whole decision about whether to keep that mechanism rests on it.
+func TestAConsumerCreatedAfterwardsStillSeesWhatCameBefore(t *testing.T) {
+	js := aLiveBus(t)
+	if err := AssertMeshStreams(js); err != nil {
+		t.Fatal(err)
+	}
+	if err := js.Context().PurgeStream("EVENTS"); err != nil {
+		t.Fatal(err)
+	}
+
+	// Genesis: things are built before anything is listening.
+	built := []string{"base", "store", "mesh-catalog"}
+	for _, m := range built {
+		if _, err := js.Context().Publish("mesh.seat.mesh-build-machine.event.built",
+			[]byte(`{"module":"`+m+`"}`)); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	// Now the catalogue is installed and the controller creates its consumer.
+	c, ok := ConsumerFor(Principal{Kind: KindModule, Node: "one", Module: "mesh-catalog",
+		Watches: []Seat{{Name: "mesh-build-machine", Emits: []string{"built"}}}, PasswordHash: "x"})
+	if !ok {
+		t.Fatal("a module that watches a role got no consumer")
+	}
+	t.Cleanup(func() { _ = js.Context().DeleteConsumer(c.Stream, c.Name) })
+	if err := js.EnsureConsumer(c); err != nil {
+		t.Fatal(err)
+	}
+
+	info, err := js.Context().ConsumerInfo(c.Stream, c.Name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if info.NumPending != uint64(len(built)) {
+		t.Fatalf("a consumer created after %d builds has %d waiting for it — if this is 0 the mesh "+
+			"does need a catch-up after all, and the reasoning for deleting it is wrong",
+			len(built), info.NumPending)
+	}
+}
@@ -0,0 +1,139 @@
+package broker
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// Whether a mesh could move its bus, and what is missing if not.
+//
+// **Asked before anything moves, and answerable from records alone.** The rollout moves every node at
+// once (novox/hq ADR 0116 step 5), so there is no partial state to inspect afterwards and no half to
+// roll back: either the mesh was ready or it was not. That makes a readiness question the most
+// valuable thing here — it costs nothing, it can be asked of a running mesh any number of times, and
+// every answer is a thing somebody can go and fix.
+//
+// Deliberately pure. It is handed what the mesh knows and returns sentences; nothing here connects to
+// anything, so it can be asked on a workstation about a mesh it has never reached.
+
+// Readiness is what the mesh knows about its own ability to move.
+type Readiness struct {
+	// TheBus is the address the mesh's own traffic would move to, empty when nothing names one.
+	TheBus string
+	// ServerStanding is whether a bus is reachable at that address, as somebody checked.
+	ServerStanding bool
+	// Holder is the node running the module that holds the bus seat, empty when nothing does.
+	Holder string
+	// AccountsComposed is whether that node has been sent the composed user list.
+	AccountsComposed bool
+	// Nodes is every machine the mesh knows.
+	Nodes []string
+	// Credentialled is which of them has a credential for the new bus.
+	Credentialled map[string]bool
+	// Modules is every assigned module, as `<node>/<module>`.
+	Modules []string
+	// ModuleCredentialled is which of those has one.
+	ModuleCredentialled map[string]bool
+}
+
+// NotReady is every reason this mesh cannot move its bus yet, in the order somebody would fix them.
+//
+// Empty means ready. **Each entry names one thing and what to do about it**, because a readiness check
+// that says "not ready" is a check nobody can act on — and this is read at the point where the next
+// step is irreversible.
+func NotReady(r Readiness) []string {
+	var why []string
+
+	if strings.TrimSpace(r.TheBus) == "" {
+		why = append(why, "nothing names the bus to move to: set "+NATSVar+" on the control node "+
+			"to the address the new server answers on")
+	}
+	if !r.ServerStanding {
+		why = append(why, "no bus is answering at that address. Step 2 of the change raises it beside "+
+			"the one the mesh is on, carrying nothing — assign the module that holds "+
+			"mesh-broker and push the machine that runs it")
+	}
+	if r.Holder == "" {
+		why = append(why, "no machine holds mesh-broker, so nothing would compose the bus's user "+
+			"list. Assign the module that claims it")
+	} else if !r.AccountsComposed {
+		why = append(why, fmt.Sprintf(
+			"%s holds mesh-broker and has not been sent the composed user list, so the bus would "+
+				"refuse every connection. `push %s`", r.Holder, r.Holder))
+	}
+
+	// A node with no credential cannot come back after the move, and a node that cannot come back is
+	// a machine the mesh has lost until somebody goes to it.
+	var missing []string
+	for _, n := range r.Nodes {
+		if !r.Credentialled[n] {
+			missing = append(missing, n)
+		}
+	}
+	sort.Strings(missing)
+	if len(missing) > 0 {
+		why = append(why, fmt.Sprintf(
+			"%d machine(s) have no credential for the new bus and would not come back: %s. Each needs "+
+				"one minted before the move, not after — after, there is no bus to ask over",
+			len(missing), strings.Join(missing, ", ")))
+	}
+
+	// A module without one keeps running and stops being reachable, which is a smaller fault and still
+	// one somebody should choose rather than discover.
+	var quiet []string
+	for _, m := range r.Modules {
+		if !r.ModuleCredentialled[m] {
+			quiet = append(quiet, m)
+		}
+	}
+	sort.Strings(quiet)
+	if len(quiet) > 0 {
+		why = append(why, fmt.Sprintf(
+			"%d module(s) have no credential for the new bus: %s. Each keeps serving and stops "+
+				"answering tools and hearing events until it is issued one",
+			len(quiet), strings.Join(quiet, ", ")))
+	}
+
+	return why
+}
+
+// WhatMoves is what the rollout would do, in order, for somebody reading before they commit.
+//
+// **Written out rather than summarised.** This is the one step with nothing to inspect afterwards, so
+// the last useful moment to disagree with it is while reading this.
+func WhatMoves(r Readiness) []string {
+	out := []string{
+		fmt.Sprintf("compose the bus's user list and send it to %s", holderOr(r.Holder)),
+		fmt.Sprintf("move this control plane to %s, and confirm it is heard", busOr(r.TheBus)),
+	}
+	nodes := append([]string(nil), r.Nodes...)
+	sort.Strings(nodes)
+	for _, n := range nodes {
+		out = append(out, fmt.Sprintf("move %s, and confirm it reports", n))
+	}
+	if len(r.Modules) > 0 {
+		out = append(out, fmt.Sprintf("move %d module runtime(s), and confirm each answers",
+			len(r.Modules)))
+	}
+	// **The old broker goes, and it goes last** (novox/hq ADR 0131). AMQP is not a provision, so once
+	// every machine reports on the new bus nothing of the mesh is left speaking to it, and its module
+	// is unassigned. Said as a step so nobody reads the move as leaving a second bus behind.
+	out = append(out, "then unassign the old broker's module: AMQP is not a provision (ADR 0131), and "+
+		"once every machine reports on the new bus nothing of the mesh speaks to it")
+	return out
+}
+
+func holderOr(node string) string {
+	if node == "" {
+		return "whichever machine holds mesh-broker"
+	}
+	return node
+}
+
+func busOr(address string) string {
+	if address == "" {
+		return "the new bus"
+	}
+	return address
+}
@@ -0,0 +1,98 @@
+package broker
+
+import (
+	"strings"
+	"testing"
+)
+
+// Whether a mesh could move its bus.
+//
+// Every case here is a way of moving that leaves something behind, and the one that matters most is a
+// machine with no credential: after the move there is no bus to ask it over, so it is lost until
+// somebody walks to it.
+
+func aMeshReadyToMove() Readiness {
+	return Readiness{
+		TheBus: "nats://127.0.0.1:5671", ServerStanding: true,
+		Holder: "anchor", AccountsComposed: true,
+		Nodes:               []string{"anchor", "laptop"},
+		Credentialled:       map[string]bool{"anchor": true, "laptop": true},
+		Modules:             []string{"anchor/gitea"},
+		ModuleCredentialled: map[string]bool{"anchor/gitea": true},
+	}
+}
+
+func TestAMeshWithEverythingInPlaceIsReady(t *testing.T) {
+	if why := NotReady(aMeshReadyToMove()); len(why) != 0 {
+		t.Fatalf("a mesh with everything in place was refused: %v", why)
+	}
+}
+
+// **A machine with no credential is the one that must stop this.** It keeps running and cannot come
+// back, and there is no bus left to tell it anything over — so the remedy has to happen before, and
+// the message says so.
+func TestAMachineWithNoCredentialStopsTheMove(t *testing.T) {
+	r := aMeshReadyToMove()
+	r.Credentialled = map[string]bool{"anchor": true}
+
+	why := NotReady(r)
+	if len(why) == 0 {
+		t.Fatal("a machine that could not come back did not stop the move")
+	}
+	said := strings.Join(why, "\n")
+	if !strings.Contains(said, "laptop") {
+		t.Errorf("the refusal does not name the machine: %s", said)
+	}
+	if !strings.Contains(said, "before the move") {
+		t.Errorf("the refusal does not say the remedy comes first: %s", said)
+	}
+}
+
+// A bus nobody has raised, a seat nobody holds, and a user list nobody has been sent: each stops it,
+// and each names its own next step, because "not ready" that cannot be acted on is not an answer.
+func TestEachThingMissingNamesItsOwnRemedy(t *testing.T) {
+	for _, c := range []struct {
+		what   string
+		break_ func(*Readiness)
+		says   string
+	}{
+		{"no address", func(r *Readiness) { r.TheBus = "" }, NATSVar},
+		{"no server", func(r *Readiness) { r.ServerStanding = false }, "carrying nothing"},
+		{"no holder", func(r *Readiness) { r.Holder = "" }, "mesh-broker"},
+		{"no user list", func(r *Readiness) { r.AccountsComposed = false }, "push anchor"},
+		{"a module with none", func(r *Readiness) {
+			r.ModuleCredentialled = map[string]bool{}
+		}, "anchor/gitea"},
+	} {
+		r := aMeshReadyToMove()
+		c.break_(&r)
+		why := NotReady(r)
+		if len(why) == 0 {
+			t.Errorf("%s did not stop the move", c.what)
+			continue
+		}
+		if !strings.Contains(strings.Join(why, "\n"), c.says) {
+			t.Errorf("%s: the refusal does not mention %q: %v", c.what, c.says, why)
+		}
+	}
+}
+
+// What the move would do is written out rather than summarised, because this is the one step with
+// nothing to inspect afterwards — so reading it is the last chance to disagree.
+func TestWhatMovesNamesEveryMachineAndEndsWithTheOldBrokerGoing(t *testing.T) {
+	r := aMeshReadyToMove()
+	steps := strings.Join(WhatMoves(r), "\n")
+
+	for _, want := range []string{"anchor", "laptop", "user list", "module runtime"} {
+		if !strings.Contains(steps, want) {
+			t.Errorf("the plan does not mention %q:\n%s", want, steps)
+		}
+	}
+	// Said explicitly, and last: AMQP is not a provision (novox/hq ADR 0131), so the move ends with
+	// the old broker's module unassigned, not left behind as a second bus. An earlier version of this
+	// test pinned the opposite, under a record 0131 superseded.
+	lines := WhatMoves(r)
+	if last := lines[len(lines)-1]; !strings.Contains(last, "unassign the old broker") {
+		t.Errorf("the plan does not end with the old broker going:\n%s", steps)
+	}
+}
@@ -0,0 +1,44 @@
+package broker_test
+
+import (
+	"slices"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/broker"
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// The facts the control plane states are named twice — in the grant that permits them and in the code
+// that states them — because `link` imports `broker` and the dependency cannot go the other way. So a
+// test keeps them agreeing: a subject the grant omits is refused at the moment the mesh has something
+// to say, and one the grant adds that nothing states is authority nobody uses.
+//
+// An external test package, because it may import both while neither imports the other.
+func TestTheFactsTheGrantPermitsAreTheFactsTheMeshStates(t *testing.T) {
+	if broker.ControllerSeat != link.MeshControllerSeat {
+		t.Fatalf("the grant is written for the %q seat and the mesh states its facts under %q",
+			broker.ControllerSeat, link.MeshControllerSeat)
+	}
+	for _, event := range []string{link.KeyApplied, link.KeyRefused, link.KeyBuiltBefore} {
+		if !slices.Contains(broker.ControllerStates, event) {
+			t.Errorf("the mesh states %q and its account may not publish it", event)
+		}
+	}
+	if len(broker.ControllerStates) != 3 {
+		t.Errorf("the grant permits %v, which is more than the mesh states", broker.ControllerStates)
+	}
+	// **And the seat says it.** A seat carries the protocol of its role (novox/hq ADR 0129), so the
+	// facts the control plane states are the seat's `emits` — which is what lets anything else declare
+	// that it consumes them, and what the subject-agreement check reads to know they have an owner.
+	var declared []string
+	for _, seat := range catalogue.SeatsWithAProtocol() {
+		if seat.Name == broker.ControllerSeat {
+			declared = seat.Emits
+		}
+	}
+	if !slices.Equal(declared, broker.ControllerStates) {
+		t.Errorf("the %s seat emits %v and the grant permits %v", broker.ControllerSeat,
+			declared, broker.ControllerStates)
+	}
+}
@@ -0,0 +1,252 @@
+package broker
+
+import (
+	"fmt"
+	"sort"
+)
+
+// The mesh's own streams.
+//
+// **These four and no more** (novox/hq ADR 0116 task 1.4, as revised by ADR 0118). An earlier
+// reading had the controller create *every* stream at genesis, from a fixed set. That is only the
+// mesh's own half: a seat's streams are created when the module declaring it is registered, and a
+// module's durable consumers when it is assigned — neither of which has happened at genesis. What
+// is here is the foundation, which exists before any module does.
+//
+// The controller is the only writer of stream definitions (design 25 §3). A module declares
+// nothing about them and cannot reach the JetStream API to make one.
+
+// Retention is how a stream decides what to keep, which is the whole of what distinguishes the
+// mesh's four relationships on the wire (design 29 §4).
+type Retention string
+
+const (
+	// RetentionWorkQueue: a message is removed once a consumer acknowledges it. Exactly one
+	// worker does the work, and a worker that dies has its message redelivered.
+	RetentionWorkQueue Retention = "workqueue"
+	// RetentionLastPerSubject: only the newest message on each subject survives. This is the
+	// state shape — a node that was away gets exactly the current declaration and nothing older.
+	RetentionLastPerSubject Retention = "last_per_subject"
+	// RetentionLimits: kept until it ages or the stream fills. Events, where a subscriber that
+	// was down catches up and nobody is obliged to act.
+	RetentionLimits Retention = "limits"
+)
+
+// A Stream is one of the mesh's own, as the controller asserts it.
+type Stream struct {
+	Name      string
+	Subjects  []string
+	Retention Retention
+	// MaxAge in seconds, zero for unbounded. Per stream — JetStream has no per-subject age,
+	// which is why differing retention between modules would mean a stream each.
+	MaxAge int
+	// MaxMsgsPerSubject caps each subject independently, so one noisy emitter cannot push
+	// another's events out of a shared stream. Verified: with a cap of 3, ten messages on one
+	// subject and one on another leave four in the stream, not three.
+	MaxMsgsPerSubject int
+	// Why is carried into the assertion so an operator reading the server's own state finds the
+	// reason there, rather than only in a repository they may not have.
+	Why string
+}
+
+// MeshStreams is the foundation set, in the order a person reads it.
+//
+// **CONTROL names its subjects rather than taking `mesh.control.>`**, because heartbeats live
+// under that prefix and must not be persisted: a lost heartbeat is the next heartbeat, and a
+// stream of them is a stream of the least valuable messages the mesh sends, competing for the
+// same retention as the ones that matter.
+//
+// **EVENTS filters on the `event` token**, which is the reason that token exists. A module's
+// namespace carries both its events and its tool calls; a filter of `mesh.mod.*.>` would persist
+// every tool invocation in the mesh, and a tool call must never be persisted (design 25 §3 keeps
+// tools on core NATS, where a lost call is a timeout the caller already handles).
+func MeshStreams() []Stream {
+	return []Stream{
+		{
+			Name: "CONTROL",
+			// A build's outcome is no longer here: it is the build-machine seat's own event, so one
+			// publish reaches whoever asked, the controller and the catalogue (novox/hq ADR 0121).
+			Subjects:  []string{"mesh.control.*.report", "mesh.control.enrol"},
+			Retention: RetentionWorkQueue,
+			Why: "the store-window guarantee (ADR 0083): the controller naks with a delay while its " +
+				"store is away and the message is redelivered; nothing is dropped",
+		},
+		{
+			Name:      "NODES",
+			Subjects:  []string{"mesh.node.*.declare"},
+			Retention: RetentionLastPerSubject,
+			Why: "one declaration per node, always the newest; a node that sees sequence n refuses " +
+				"n-1 by construction (issue 107)",
+		},
+		{
+			Name: "EVENTS",
+			// A seat's own events ride here too: they are 1:many like any event, and the
+			// `event` token keeps them clear of both the seat's work queue (`accept`) and its
+			// tools (`tool`), which must not be persisted.
+			Subjects:          []string{"mesh.mod.*.event.>", "mesh.seat.*.event.>"},
+			Retention:         RetentionLimits,
+			MaxAge:            7 * 24 * 60 * 60,
+			MaxMsgsPerSubject: 10000,
+			Why: "a subscriber that was down catches up; tool traffic under the same prefix is " +
+				"excluded by the event token; per-subject caps keep a noisy emitter from " +
+				"evicting a quiet one without splitting the stream",
+		},
+	}
+}
+
+// An Asserter is the part of a JetStream connection stream assertion needs. Narrow on purpose: it
+// keeps this testable without a server, and keeps the client library out of everything that only
+// wants to know what the streams are.
+type Asserter interface {
+	// EnsureStream creates the stream if absent and updates it to match if present. It must be
+	// idempotent: the controller asserts on every start, not only at genesis.
+	EnsureStream(s Stream) error
+}
+
+// AssertMeshStreams brings the foundation set into being, in order, and says which one failed
+// rather than that something did.
+//
+// Asserted on every start rather than created once at genesis, because a stream that was deleted,
+// or a mesh raised from a restored backup, must converge rather than run without the guarantee
+// its messages assume. Idempotence is the whole requirement.
+func AssertMeshStreams(a Asserter) error {
+	for _, s := range MeshStreams() {
+		if err := a.EnsureStream(s); err != nil {
+			return fmt.Errorf("asserting stream %s: %w", s.Name, err)
+		}
+	}
+	return nil
+}
+
+// Overlaps reports subject filters claimed by more than one stream.
+//
+// **Corrected against the server**: an earlier version of this comment said NATS accepts
+// overlapping streams and stores the message twice. It does not — it refuses the second stream
+// with "subjects overlap with an existing stream" (verified against nats-server 2.10). The check
+// still earns its place, for a different reason: the server's refusal arrives when the controller
+// is applying, naming one stream, at a moment when the mesh is half-configured. This one arrives
+// where the set is written, names both, and cannot reach a running mesh.
+//
+// It also decides a design question. Because overlap is refused rather than merged, a shared
+// EVENTS stream and a per-module stream cannot coexist — the module's would be refused — so
+// "one stream for most, its own for a module that wants different retention" is not an option
+// the server allows. It is all of one or all of the other.
+func Overlaps() []string {
+	seen := map[string]string{}
+	var clashes []string
+	for _, s := range MeshStreams() {
+		for _, subject := range s.Subjects {
+			if first, ok := seen[subject]; ok {
+				clashes = append(clashes, fmt.Sprintf("%s and %s both claim %s", first, s.Name, subject))
+				continue
+			}
+			seen[subject] = s.Name
+		}
+	}
+	sort.Strings(clashes)
+	return clashes
+}
+
+// The mesh's own consumers.
+//
+// A seat's streams and a module's consumers are derived from declarations (derived.go). These two
+// are not: **the controller is not a module and files no manifest**, so its authority and its
+// subscriptions cannot come from a declaration that does not exist. They are named here, where the
+// mesh's own streams are named, and narrowly — a controller subscribing `mesh.mod.*.event.>` would
+// hear every event in the mesh, which it has no business doing and which would make its permission
+// list stop explaining anything.
+
+// ControllerName is the controller's durable consumer on each stream it reads, and the name its
+// ack subject is derived from (nats.go: `$JS.ACK.<stream>.controller.>`).
+const ControllerName = "controller"
+
+// ControllerSeat is the role the control plane holds, and ControllerStates are the facts it states
+// under it (novox/hq ADR 0134).
+//
+// **Written here as well as in `link`, and a test keeps them agreeing.** `link` imports `broker`, so
+// `broker` cannot import `link`; a grant naming a subject the controller never publishes is authority
+// nobody uses, and a controller publishing one the grant omits is refused at the moment it has
+// something to say.
+const ControllerSeat = "mesh-controller"
+
+var ControllerStates = []string{"applied", "refused", "built-before"}
+
+// ControllerFollows are the events the controller reacts to: the catalogue saying a module's
+// current version moved, and a catalogue that has just started saying it may have missed builds.
+//
+// **Derived the same way a module's subscription is**, from the emitter and the bare local event
+// name, rather than written out. They were written out while the catalogue still spelled its events
+// as the old bus's routing keys, and the moment those were converted (novox/hq 04-ISSUES/127) a
+// hard-coded pair became a controller listening to a subject nothing publishes — the same fault, from
+// the other side. Deriving them means the conversion could not leave these behind.
+var ControllerFollows = []string{
+	moduleEventSubject("mesh-catalog", "upgraded"),
+	moduleEventSubject("mesh-catalog", "catching-up"),
+	// A build's outcome, which is the build-machine role's own event now (ADR 0121) rather than a
+	// message on the control branch. Same three audiences, one publish: whoever asked, this, and the
+	// catalogue.
+	seatEventSubject("mesh-build-machine", "built"),
+	// The forge's merges: what moved a source, so the mesh builds what that source produces
+	// without anybody telling it (novox/hq 04-ISSUES/131). Appended, because the index is a name.
+	moduleEventSubject("gitea", "pull.merged"),
+}
+
+// moduleEventSubject is where one module's event lands. The same derivation PermissionsFor uses, so
+// what the controller subscribes and what the emitter is permitted to publish cannot drift apart.
+func moduleEventSubject(module, event string) string {
+	return "mesh.mod." + module + ".event." + event
+}
+
+// seatEventSubject is where a role's own event lands, derived the same way a holder's permission is.
+func seatEventSubject(seat, verb string) string {
+	return "mesh.seat." + seat + ".event." + verb
+}
+
+// MeshConsumers is what the controller consumes, in the order a person reads it.
+//
+// **Unlimited redelivery on CONTROL, deliberately.** The store window's bound is the controller's,
+// not the server's (window.go): a message is held with a nak-and-delay until the controller either
+// takes it or gives up and says so. A max-deliver here would dead-letter a push that was being
+// held through a store restart — the exact message the stream exists to protect — some minutes
+// before the controller had finished deciding about it.
+func MeshConsumers() []Consumer {
+	return []Consumer{
+		{
+			Name:           ControllerName,
+			Stream:         "CONTROL",
+			Push:           true,
+			AckWaitSeconds: 30,
+			Why: "the controller is the single consumer of what nodes say; explicit ack and no " +
+				"max-deliver, because the store window's bound is the controller's own",
+		},
+		{
+			Name:           ControllerName,
+			Stream:         "EVENTS",
+			Filters:        ControllerFollows,
+			Push:           true,
+			AckWaitSeconds: 30,
+			MaxDeliver:     5,
+			Why: "the two events the mesh's own controller reacts to; after max-deliver it " +
+				"dead-letters, because an announcement it cannot act on will not become actionable",
+		},
+	}
+}
+
+// Ensurer is the part of a JetStream connection consumer assertion needs, narrow for the reason
+// Asserter is.
+type Ensurer interface {
+	EnsureConsumer(c Consumer) error
+}
+
+// AssertMeshConsumers brings the controller's own consumers into being, and says which one failed.
+//
+// After the streams, necessarily: a consumer on a stream that does not exist is refused, and the
+// refusal names the stream rather than the order.
+func AssertMeshConsumers(e Ensurer) error {
+	for _, c := range MeshConsumers() {
+		if err := e.EnsureConsumer(c); err != nil {
+			return fmt.Errorf("asserting consumer %s on %s: %w", c.Name, c.Stream, err)
+		}
+	}
+	return nil
+}
@@ -0,0 +1,235 @@
+package broker
+
+import (
+	"errors"
+	"strings"
+	"testing"
+)
+
+type recorder struct {
+	seen []Stream
+	fail string
+}
+
+func (r *recorder) EnsureStream(s Stream) error {
+	if s.Name == r.fail {
+		return errors.New("refused")
+	}
+	r.seen = append(r.seen, s)
+	return nil
+}
+
+// The controller asserts on every start, not only at genesis: a stream that was deleted, or a mesh
+// raised from a backup, must converge rather than run without the guarantee its messages assume.
+func TestAssertingTwiceIsTheSameAsOnce(t *testing.T) {
+	a, b := &recorder{}, &recorder{}
+	if err := AssertMeshStreams(a); err != nil {
+		t.Fatal(err)
+	}
+	if err := AssertMeshStreams(a); err != nil {
+		t.Fatal(err)
+	}
+	if err := AssertMeshStreams(b); err != nil {
+		t.Fatal(err)
+	}
+	if len(a.seen) != 2*len(b.seen) {
+		t.Fatalf("asserted %d then %d; assertion is not repeatable", len(a.seen), len(b.seen))
+	}
+}
+
+func TestAFailedAssertionNamesItsStream(t *testing.T) {
+	err := AssertMeshStreams(&recorder{fail: "NODES"})
+	if err == nil || !strings.Contains(err.Error(), "NODES") {
+		t.Fatalf("got %v, which does not say which stream failed", err)
+	}
+}
+
+// Two streams matching one subject is accepted by NATS and stores the message twice under two
+// retentions. Nothing reports that, so it is refused where the set is written.
+func TestNoTwoStreamsClaimTheSameSubject(t *testing.T) {
+	if clashes := Overlaps(); len(clashes) != 0 {
+		t.Fatalf("overlapping subject filters: %v", clashes)
+	}
+}
+
+// A heartbeat under mesh.control.> must not be persisted: a lost one is the next one, and a
+// stream of them competes for retention with the messages that matter.
+func TestHeartbeatsAreNotInTheControlStream(t *testing.T) {
+	for _, s := range MeshStreams() {
+		for _, subject := range s.Subjects {
+			if subject == "mesh.control.>" || strings.Contains(subject, "alive") {
+				t.Fatalf("stream %s claims %q, which captures heartbeats", s.Name, subject)
+			}
+		}
+	}
+}
+
+// The reason the kind token exists: a filter over a module's whole namespace would persist every
+// tool call in the mesh.
+func TestTheEventsStreamDoesNotCaptureToolCalls(t *testing.T) {
+	var events Stream
+	for _, s := range MeshStreams() {
+		if s.Name == "EVENTS" {
+			events = s
+		}
+	}
+	// Nothing a tool call rides may match any of the filters — a module's or a seat's.
+	for _, tool := range []string{
+		"mesh.mod.billing.tool.status",
+		"mesh.seat.telegram-sender.tool.status",
+		"mesh.seat.telegram-sender.accept.send", // work, not an event: its own stream
+	} {
+		for _, f := range events.Subjects {
+			if subjectMatches(f, tool) {
+				t.Fatalf("%q matches the events filter %q, so it would be persisted here", tool, f)
+			}
+		}
+	}
+	// And both kinds of event do match.
+	for _, event := range []string{
+		"mesh.mod.billing.event.order.placed",
+		"mesh.seat.telegram-sender.event.delivered",
+	} {
+		matched := false
+		for _, f := range events.Subjects {
+			if subjectMatches(f, event) {
+				matched = true
+			}
+		}
+		if !matched {
+			t.Fatalf("%q matches no events filter, so nothing would keep it", event)
+		}
+	}
+}
+
+// subjectMatches is NATS subject matching, enough for these filters: `*` is one token, `>` is the
+// rest.
+func subjectMatches(filter, subject string) bool {
+	f, s := strings.Split(filter, "."), strings.Split(subject, ".")
+	for i, tok := range f {
+		if tok == ">" {
+			return i <= len(s)
+		}
+		if i >= len(s) {
+			return false
+		}
+		if tok != "*" && tok != s[i] {
+			return false
+		}
+	}
+	return len(f) == len(s)
+}
+
+// Each relationship's retention is the thing that makes it what it is (design 29 §4).
+func TestEachStreamCarriesTheRetentionItsShapeNeeds(t *testing.T) {
+	want := map[string]Retention{
+		"CONTROL": RetentionWorkQueue,
+		"NODES":   RetentionLastPerSubject,
+		"EVENTS":  RetentionLimits,
+	}
+	got := map[string]Retention{}
+	for _, s := range MeshStreams() {
+		got[s.Name] = s.Retention
+		if s.Why == "" {
+			t.Errorf("stream %s says no reason it exists", s.Name)
+		}
+	}
+	if len(got) != len(want) {
+		t.Fatalf("the foundation set is %v", got)
+	}
+	for name, r := range want {
+		if got[name] != r {
+			t.Errorf("%s retains as %q, expected %q", name, got[name], r)
+		}
+	}
+}
+
+// The order the bus's objects are asserted in, because getting it wrong is a refusal that names the
+// wrong thing: a consumer on a stream that does not exist is refused naming the *stream*, so
+// somebody reading it goes looking for a deletion instead of a reversed pair of lines.
+func TestTheBusesObjectsAreAssertedStreamsBeforeConsumers(t *testing.T) {
+	r := &recording{}
+	if err := Raise(r, []string{"anchor", "laptop"}); err != nil {
+		t.Fatal(err)
+	}
+
+	// Every stream before every consumer.
+	firstConsumer := -1
+	for i, step := range r.steps {
+		if strings.HasPrefix(step, "consumer ") && firstConsumer < 0 {
+			firstConsumer = i
+		}
+		if strings.HasPrefix(step, "stream ") && firstConsumer >= 0 {
+			t.Fatalf("a stream was asserted after a consumer: %v", r.steps)
+		}
+	}
+	if firstConsumer < 0 {
+		t.Fatalf("no consumer was asserted: %v", r.steps)
+	}
+
+	// And every node got one, named after it — without which that node hears nothing while
+	// everything else about it looks correct.
+	for _, node := range []string{"anchor", "laptop"} {
+		if !containsStep(r.steps, "consumer NODES/"+node) {
+			t.Errorf("%s was given no way to hear its declaration: %v", node, r.steps)
+		}
+	}
+	// And the controller its own, on both streams it reads.
+	for _, want := range []string{"consumer CONTROL/controller", "consumer EVENTS/controller"} {
+		if !containsStep(r.steps, want) {
+			t.Errorf("the controller is missing %s: %v", want, r.steps)
+		}
+	}
+}
+
+// A seat's work queue is asserted whether or not anybody holds it; the holder's worker only when
+// somebody does. **The stream without the consumer is the point**: work queues until a holder
+// appears, so installing the module later flushes the backlog instead of having lost it.
+func TestASeatsQueueExistsBeforeItsHolderDoes(t *testing.T) {
+	seats := []DeclaredSeat{{Name: "telegram-sender", Accepts: []string{"send"}}}
+
+	unheld := &recording{}
+	if err := RaiseSeats(unheld, seats, nil); err != nil {
+		t.Fatal(err)
+	}
+	if !containsStep(unheld.steps, "stream SEAT_TELEGRAM_SENDER") {
+		t.Fatalf("a declared seat got no work queue: %v", unheld.steps)
+	}
+	for _, step := range unheld.steps {
+		if strings.HasPrefix(step, "consumer ") {
+			t.Fatalf("a seat nobody holds got a worker: %v", unheld.steps)
+		}
+	}
+
+	held := &recording{}
+	if err := RaiseSeats(held, seats, map[string]Holder{
+		"telegram-sender": {Node: "anchor", Module: "telegram"},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	if !containsStep(held.steps, "consumer SEAT_TELEGRAM_SENDER/SEAT_TELEGRAM_SENDER_worker") {
+		t.Fatalf("the seat's holder got no worker: %v", held.steps)
+	}
+}
+
+// recording is a connection to the bus that writes down what it was asked for.
+type recording struct{ steps []string }
+
+func (r *recording) EnsureStream(s Stream) error {
+	r.steps = append(r.steps, "stream "+s.Name)
+	return nil
+}
+
+func (r *recording) EnsureConsumer(c Consumer) error {
+	r.steps = append(r.steps, "consumer "+c.Stream+"/"+c.Name)
+	return nil
+}
+
+func containsStep(steps []string, want string) bool {
+	for _, s := range steps {
+		if s == want {
+			return true
+		}
+	}
+	return false
+}
@@ -0,0 +1,56 @@
+# Composed by the mesh controller. Do not edit: the next composition overwrites it.
+# Accounts and permissions are derived from what each module declares and nothing
+# else (novox/hq ADR 0043, design 29 §2).
+
+port: 4222
+http: 127.0.0.1:8222
+
+tls {
+  cert_file: "/tls/tls.crt"
+  key_file: "/tls/tls.key"
+  ca_file: "/tls/ca.crt"
+}
+
+jetstream {
+  store_dir: "/data"
+}
+
+# The mesh's users, composed by the controller. Do not edit: the next
+# composition overwrites it. Permissions are derived from what each module
+# declares and nothing else (novox/hq ADR 0043, design 29 §2).
+
+accounts {
+  MESH {
+    jetstream: enabled
+    users = [
+      { user: "controller", password: "$2a$11$cccccccccccccccccccccc", permissions: {
+        publish: { allow: ["$JS.ACK.CONTROL.controller.>", "$JS.ACK.EVENTS.controller.>", "$JS.API.>", "_INBOX.enrol.>", "mesh.control.>", "mesh.mod.*.tool.>", "mesh.node.>", "mesh.seat.mesh-build-machine.accept.>", "mesh.seat.mesh-controller.event.applied", "mesh.seat.mesh-controller.event.built-before", "mesh.seat.mesh-controller.event.refused"] }
+        subscribe: { allow: ["$JS.API.>", "_DELIVER.controller", "_DELIVER.controller.>", "_INBOX.controller.>", "mesh.control.>", "mesh.mod.gitea.event.pull.merged", "mesh.mod.mesh-catalog.event.catching-up", "mesh.mod.mesh-catalog.event.upgraded", "mesh.seat.mesh-build-machine.event.built"] }
+        allow_responses: { max: 1, ttl: "1m" }
+      } }
+      { user: "enrol.one", password: "$2a$11$eeeeeeeeeeeeeeeeeeeeee", permissions: {
+        publish: { allow: ["mesh.control.enrol"] }
+        subscribe: { allow: ["_INBOX.enrol.one.>"] }
+      } }
+      { user: "node.one", password: "$2a$11$nnnnnnnnnnnnnnnnnnnnnn", permissions: {
+        publish: { allow: ["$JS.ACK.NODES.one.>", "$JS.API.CONSUMER.INFO.NODES.one", "mesh.control.one.>"] }
+        subscribe: { allow: ["_DELIVER.one", "_INBOX.node.one.>", "mesh.node.one.declare"] }
+      } }
+      { user: "one.telegram", password: "$2a$11$tttttttttttttttttttttt", permissions: {
+        publish: { allow: ["$JS.ACK.EVENTS.one_telegram.>", "$JS.ACK.SEAT_TELEGRAM_SENDER.SEAT_TELEGRAM_SENDER_worker.>", "$JS.API.CONSUMER.INFO.EVENTS.one_telegram", "$JS.API.CONSUMER.INFO.SEAT_TELEGRAM_SENDER.SEAT_TELEGRAM_SENDER_worker", "$JS.API.CONSUMER.MSG.NEXT.EVENTS.one_telegram", "mesh.seat.telegram-sender.event.delivered", "mesh.seat.telegram-sender.event.failed"] }
+        subscribe: { allow: ["_DELIVER.SEAT_TELEGRAM_SENDER_worker", "_INBOX.one.telegram.>", "mesh.mod.telegram.tool.>", "mesh.seat.telegram-sender.accept.send"] }
+        allow_responses: { max: 1, ttl: "1m" }
+      } }
+      { user: "two.audit", password: "$2a$11$aaaaaaaaaaaaaaaaaaaaaa", permissions: {
+        publish: { allow: ["$JS.ACK.EVENTS.two_audit.>", "$JS.API.CONSUMER.INFO.EVENTS.two_audit", "$JS.API.CONSUMER.MSG.NEXT.EVENTS.two_audit"] }
+        subscribe: { allow: ["_INBOX.two.audit.>", "mesh.mod.audit.tool.>", "mesh.mod.shop.event.order.placed"] }
+        allow_responses: { max: 1, ttl: "1m" }
+      } }
+      { user: "two.shop", password: "$2a$11$ssssssssssssssssssssss", permissions: {
+        publish: { allow: ["$JS.ACK.EVENTS.two_shop.>", "$JS.API.CONSUMER.INFO.EVENTS.two_shop", "$JS.API.CONSUMER.MSG.NEXT.EVENTS.two_shop", "mesh.mod.shop.event.order.placed", "mesh.seat.telegram-sender.accept.send"] }
+        subscribe: { allow: ["_INBOX.two.shop.>", "mesh.mod.shop.tool.>"] }
+        allow_responses: { max: 1, ttl: "1m" }
+      } }
+    ]
+  }
+}
@@ -0,0 +1,127 @@
+package broker
+
+import (
+	"fmt"
+	"sort"
+)
+
+// Every user the composed file should contain, derived from what the mesh knows.
+//
+// **The list is derived, never kept.** A stored user list would be a second account of who may
+// reach the bus, able to disagree with the records it came from — and the disagreement would be
+// invisible, because both would look internally consistent. So this is a pure function of the
+// mesh's records, run again every time the file is written.
+//
+// Records are mirrored into this package's own types rather than imported from the catalogue, for
+// the reason DeclaredSeat is: composing authority is a different job from parsing a manifest, and
+// this package stays free of the other's types so a change to a manifest field cannot quietly widen
+// a permission.
+
+// Declared is one module on one node, as composing its authority needs it.
+type Declared struct {
+	Module   string
+	Emits    []string
+	Consumes []string
+	Serves   []string
+	// Holds are the seats this module claims, with the protocol each seat declares. A seat the
+	// mesh defines for itself declares no protocol, so holding one grants nothing on the bus —
+	// which is right: those seats are about who does a job, not about who may say what.
+	Holds []Seat
+	// Uses are the seats this module sends to.
+	Uses []Seat
+	// Watches are the seats whose events it consumes.
+	Watches []Seat
+}
+
+// Records is what composing a user list needs to know about the mesh, and nothing more.
+type Records struct {
+	// Nodes is every machine the mesh knows. Each gets a host user.
+	Nodes []string
+	// Assigned is the modules on each node, as they declare themselves.
+	Assigned map[string][]Declared
+	// Enrolling is every node with a live token — one enrolment user each, because the inbox an
+	// answer goes to is scoped to the token and a shared one is one machine reading another's
+	// sealed credentials (design 25 §6).
+	Enrolling []string
+	// People is each person's name against the tools they may invoke, `*` for an administrator.
+	People map[string][]string
+}
+
+// Users is every user the composed file should contain, in the order it will be written.
+//
+// The controller is always first and always present: a mesh whose own controller is not in the file
+// is a mesh that cannot be told anything, and there is no state of the records in which that is
+// correct.
+func Users(r Records) ([]Principal, error) {
+	out := []Principal{{Kind: KindController}}
+
+	for _, node := range sortedCopy(r.Nodes) {
+		out = append(out, Principal{Kind: KindNode, Node: node})
+		for _, d := range r.Assigned[node] {
+			out = append(out, Principal{
+				Kind: KindModule, Node: node, Module: d.Module,
+				Emits: d.Emits, Consumes: d.Consumes, Serves: d.Serves,
+				Holds: d.Holds, Uses: d.Uses, Watches: d.Watches,
+			})
+		}
+	}
+	for _, node := range sortedCopy(r.Enrolling) {
+		out = append(out, Principal{Kind: KindEnrolment, Node: node})
+	}
+	for _, person := range sortedNames(r.People) {
+		out = append(out, Principal{Kind: KindPerson, Module: person, Invokes: r.People[person]})
+	}
+
+	// Refused here rather than discovered by the server. Two users with one name is a file the
+	// server reads as one of them, and which one depends on the order — so a module assigned to a
+	// node twice, or a person named after nothing, is a composition that must not be written.
+	seen := map[string]string{}
+	for _, p := range out {
+		name := p.Username()
+		if name == "" || name == "." {
+			return nil, fmt.Errorf("a %s user has no name, so nothing could authenticate as it", p.Kind)
+		}
+		if first, already := seen[name]; already {
+			return nil, fmt.Errorf(
+				"two users would be called %q (a %s and a %s): the server would read the file as "+
+					"one of them, and which one depends on the order", name, first, p.Kind)
+		}
+		seen[name] = string(p.Kind)
+	}
+	return out, nil
+}
+
+// WithPasswords fills each user's hash from what the mesh minted, and says which users have none.
+//
+// **Separated from Users because they fail differently.** A user missing from the records is a bug
+// in deriving them; a user with no password is a step that has not happened yet — a module assigned
+// but never given a credential, a node enrolled before this existed. The second is ordinary and its
+// remedy is to mint one, so it is named rather than returned as an error, and the caller decides
+// whether a partial composition is worth writing.
+func WithPasswords(principals []Principal, hashes map[string]string) (filled []Principal, missing []string) {
+	for _, p := range principals {
+		hash, ok := hashes[p.Username()]
+		if !ok || hash == "" {
+			missing = append(missing, p.Username())
+			continue
+		}
+		p.PasswordHash = hash
+		filled = append(filled, p)
+	}
+	return filled, missing
+}
+
+func sortedCopy(in []string) []string {
+	out := append([]string(nil), in...)
+	sort.Strings(out)
+	return out
+}
+
+func sortedNames(in map[string][]string) []string {
+	out := make([]string, 0, len(in))
+	for k := range in {
+		out = append(out, k)
+	}
+	sort.Strings(out)
+	return out
+}
@@ -0,0 +1,247 @@
+package broker
+
+import (
+	"strings"
+	"testing"
+)
+
+// Deriving the bus's user list from the mesh's records.
+//
+// Every test here is about a way the list could be wrong that the server would not tell anybody
+// about: a user missing, a user named twice, a user with authority it did not declare.
+
+func someRecords() Records {
+	return Records{
+		Nodes: []string{"two", "one"},
+		Assigned: map[string][]Declared{
+			"one": {{Module: "telegram", Serves: []string{"status"}}},
+			"two": {{Module: "shop", Emits: []string{"order.placed"}}},
+		},
+		Enrolling: []string{"three"},
+		People:    map[string][]string{"ada": {"mesh-catalog.catalog_tools"}},
+	}
+}
+
+func namesOf(t *testing.T, r Records) []string {
+	t.Helper()
+	users, err := Users(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+	out := make([]string, 0, len(users))
+	for _, u := range users {
+		out = append(out, u.Username())
+	}
+	return out
+}
+
+// The controller is always there. A mesh whose own controller is not in the file is a mesh that
+// cannot be told anything, and there is no state of the records in which that is correct.
+func TestTheControllerIsAlwaysInTheList(t *testing.T) {
+	for _, r := range []Records{{}, someRecords()} {
+		names := namesOf(t, r)
+		if len(names) == 0 || names[0] != "controller" {
+			t.Fatalf("the controller is not first in %v", names)
+		}
+	}
+}
+
+// One user per node, one per module per node, one per live token and one per person — and nothing
+// else, because a user nobody derived is a user nobody can explain.
+func TestEveryRecordBecomesExactlyOneUser(t *testing.T) {
+	names := namesOf(t, someRecords())
+	want := []string{
+		"controller",
+		"node.one", "one.telegram",
+		"node.two", "two.shop",
+		"enrol.three",
+		"person.ada",
+	}
+	if strings.Join(names, ",") != strings.Join(want, ",") {
+		t.Fatalf("derived %v\n    want %v", names, want)
+	}
+}
+
+// Two users with one name is a file the server reads as one of them, and which one depends on the
+// order. Refused here, where both can be named, rather than left to be whichever the server picked.
+func TestTwoUsersWithOneNameAreRefused(t *testing.T) {
+	r := someRecords()
+	r.Assigned["one"] = append(r.Assigned["one"], Declared{Module: "telegram"})
+	_, err := Users(r)
+	if err == nil {
+		t.Fatal("a module assigned twice to one node composed two users with one name")
+	}
+	if !strings.Contains(err.Error(), "one.telegram") {
+		t.Fatalf("the refusal does not name the user: %v", err)
+	}
+}
+
+// A module's authority is what it declared and nothing more, carried through the derivation intact —
+// because this is the step where a mistake would grant something no manifest asked for.
+func TestAModulesAuthorityIsWhatItDeclared(t *testing.T) {
+	seat := Seat{Name: "telegram-sender", Accepts: []string{"send"}, Emits: []string{"delivered"}}
+	users, err := Users(Records{
+		Nodes: []string{"one"},
+		Assigned: map[string][]Declared{"one": {{
+			Module: "shop", Emits: []string{"order.placed"}, Uses: []Seat{seat},
+		}}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	perms, err := PermissionsFor(users[len(users)-1])
+	if err != nil {
+		t.Fatal(err)
+	}
+	has(t, perms.Publish, "mesh.mod.shop.event.order.placed")
+	has(t, perms.Publish, "mesh.seat.telegram-sender.accept.send")
+	// A seat it uses, not one it holds: it may submit work and may not publish the seat's own
+	// events, or it could lie about outcomes on a role somebody else fills.
+	hasNot(t, perms.Publish, "mesh.seat.telegram-sender.event.delivered")
+	hasNot(t, perms.Subscribe, "mesh.seat.telegram-sender.accept.send")
+}
+
+// A user the mesh has never minted a password for is named rather than silently dropped or
+// composed as a user anybody is. It is an ordinary situation — a module assigned a moment ago — and
+// the remedy is to mint one, so the caller decides whether to write a partial file.
+func TestAUserWithNoPasswordIsNamedRatherThanWritten(t *testing.T) {
+	users, err := Users(someRecords())
+	if err != nil {
+		t.Fatal(err)
+	}
+	filled, missing := WithPasswords(users, map[string]string{
+		"controller": "$2a$hash", "node.one": "$2a$hash",
+	})
+	if len(filled) != 2 {
+		t.Fatalf("composed %d users from two hashes", len(filled))
+	}
+	if len(missing) != len(users)-2 {
+		t.Fatalf("%d users are missing a password, of %d: %v", len(missing), len(users), missing)
+	}
+	for _, p := range filled {
+		if p.PasswordHash == "" {
+			t.Fatalf("%s was kept with no password, which is a user anybody is", p.Username())
+		}
+	}
+}
+
+// And the whole thing composes: records in, a file the server would read out.
+func TestRecordsComposeIntoAFile(t *testing.T) {
+	users, err := Users(someRecords())
+	if err != nil {
+		t.Fatal(err)
+	}
+	hashes := map[string]string{}
+	for _, u := range users {
+		hashes[u.Username()] = "$2a$11$" + strings.Repeat("x", 22)
+	}
+	filled, missing := WithPasswords(users, hashes)
+	if len(missing) != 0 {
+		t.Fatalf("users with no password: %v", missing)
+	}
+	got, err := Compose(Server{ClientPort: 4222, MonitoringPort: 8222, StoreDir: "/data",
+		TLSCert: "/tls/tls.crt", TLSKey: "/tls/tls.key", TLSCA: "/tls/ca.crt"}, filled)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{
+		`user: "controller"`, `user: "node.one"`, `user: "one.telegram"`,
+		`user: "enrol.three"`, `user: "person.ada"`,
+		`"_INBOX.enrol.three.>"`, `"mesh.mod.mesh-catalog.tool.catalog_tools"`,
+	} {
+		if !strings.Contains(got, want) {
+			t.Errorf("the composed file does not contain %s", want)
+		}
+	}
+}
+
+// The accounts block alone is what the mesh writes, and it holds nothing about the server.
+//
+// **The split is the whole design decision** (ComposeAccounts): ports, TLS paths and a store
+// directory are properties of the container the module raises, and a controller that wrote them
+// would have to be kept in step with a Dockerfile it never sees. So this test says what must not be
+// in the file as plainly as what must.
+func TestWhatTheMeshWritesIsUsersAndNothingAboutTheServer(t *testing.T) {
+	users, err := Users(someRecords())
+	if err != nil {
+		t.Fatal(err)
+	}
+	hashes := map[string]string{}
+	for _, u := range users {
+		hashes[u.Username()] = "$2a$11$" + strings.Repeat("x", 22)
+	}
+	filled, missing := WithPasswords(users, hashes)
+	if len(missing) != 0 {
+		t.Fatalf("users with no password: %v", missing)
+	}
+	got, err := ComposeAccounts(filled)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, want := range []string{"accounts {", `user: "controller"`, `user: "one.telegram"`} {
+		if !strings.Contains(got, want) {
+			t.Errorf("the accounts file does not contain %s", want)
+		}
+	}
+	// None of the server's own settings. Each of these in the mesh's file is a value the controller
+	// would then own, and the module could no longer change its own image without the mesh agreeing.
+	// `jetstream {` is the server's block (its store, its limits); `jetstream: enabled` inside the
+	// account is the account's, and the mesh owns the account — a user in it is told "JetStream
+	// not enabled for account" without it (2026-09-28).
+	if !strings.Contains(got, "jetstream: enabled") {
+		t.Errorf("the account does not enable JetStream, so no user in it can bind a consumer")
+	}
+	for _, absent := range []string{"port:", "http:", "jetstream {", "tls {", "store_dir", "cert_file"} {
+		if strings.Contains(got, absent) {
+			t.Errorf("the accounts file contains %q, which belongs to the module that raises the "+
+				"server, not to the mesh", absent)
+		}
+	}
+}
+
+// A user with no password is refused here too, not only by the whole-file composition: this is the
+// function the controller actually calls, and a user without a password is a user anybody is.
+func TestTheAccountsFileRefusesAUserWithNoPassword(t *testing.T) {
+	if _, err := ComposeAccounts([]Principal{{Kind: KindController}}); err == nil {
+		t.Fatal("a user with no password hash was written")
+	}
+}
+
+// **A user list is composed for a bus the mesh has not moved onto yet**, and that is the whole of
+// step 2 (novox/hq ADR 0116): the server stands in the mesh carrying nothing, on its own ports, while
+// every node is still on the bus it was on.
+//
+// Pinned because the first version of the composing step got it backwards — it wrote the list only
+// once the controller was already on the new bus, which is a step that cannot be taken: the module
+// comes up, finds no accounts file, and waits for one the controller had decided not to write.
+func TestAUserListIsComposedBeforeAnythingMovesOntoTheBus(t *testing.T) {
+	// Exactly the records of a mesh mid-change: everything running, nothing on the new bus.
+	users, err := Users(Records{
+		Nodes:    []string{"anchor"},
+		Assigned: map[string][]Declared{"anchor": {{Module: "nats"}}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	hashes := map[string]string{}
+	for _, u := range users {
+		hashes[u.Username()] = "$2a$11$" + strings.Repeat("x", 22)
+	}
+	filled, missing := WithPasswords(users, hashes)
+	if len(missing) != 0 {
+		t.Fatalf("users with no credential: %v", missing)
+	}
+	accounts, err := ComposeAccounts(filled)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// The controller's own user above all: a file without it is a bus its writer cannot connect to,
+	// which is what the server would be left holding the moment it starts.
+	if !strings.Contains(accounts, `user: "controller"`) {
+		t.Fatalf("the composed list does not contain the controller:\n%s", accounts)
+	}
+	if !strings.Contains(accounts, `user: "node.anchor"`) {
+		t.Errorf("the composed list does not contain the machine running the bus")
+	}
+}
@@ -61,6 +61,12 @@ type Result struct {
 	Commit string
 	// Built is each artifact, for reporting.
 	Built []catalogue.Built
+
+	// Read is every repository this build read source from besides the module's own — the second
+	// repository an artifact's recipe names (ArtifactContext). Reported because the manifest the
+	// mesh keeps carries no build section, so nothing else could say that a merge there is a
+	// change to this module (novox/hq 04-ISSUES/131).
+	Read []catalogue.ArtifactContext
 }

 // GitCredential is the forge credential a clone may present when the server asks for one.
@@ -169,6 +175,8 @@ func Build(ctx context.Context, run Runner, publish Publisher,
 	}

 	var built []catalogue.Built
+	// stoodOn is every base the build was handed, as resolved — the edges the catalogue derives.
+	var stoodOn []string
 	if manifest.Build != nil {
 		// What this module said it stands on, answered with what this mesh actually holds. Done
 		// before anything is built, so a missing base is refused in front of the person who can
@@ -186,11 +194,12 @@ func Build(ctx context.Context, run Runner, publish Publisher,
 			}
 			return from, nil
 		}
-		args, err := standingOn(ctx, manifest, held, mirror)
+		args, bases, err := standingOn(ctx, manifest, held, mirror)
 		if err != nil {
 			say("bases", "UNMET: %v", err)
 			return Result{}, err
 		}
+		stoodOn = bases
 		if len(args) > 0 {
 			say("bases", "%d resolved from what the mesh holds", len(args)/2)
 		}
@@ -217,7 +226,7 @@ func Build(ctx context.Context, run Runner, publish Publisher,
 	}
 	say("done", "%s at %s — %d artifact(s) pinned", manifest.Module, short(commit), len(built))
 	return Result{Manifest: resolved, Commit: commit, Built: built,
-		Against: against(within, manifest)}, nil
+		Against: against(within, manifest, stoodOn), Read: readBy(manifest)}, nil
 }

 // Log is where a build says what it is doing, step by step. Nil is silent — the tests pass none,
@@ -339,14 +348,27 @@ func describe(path string) string {
 // allowed to name — a tag is something somebody else can move under you.
 var pinnedImage = regexp.MustCompile(`[A-Za-z0-9][A-Za-z0-9._/:-]*@sha256:[0-9a-f]{64}`)

-// against reads what this module's image artifacts are built on top of, out of the files that
-// build them. Nothing is guessed: a reference that is not written down is not reported.
-func against(within string, manifest catalogue.Manifest) []string {
+// against is what this module's image artifacts are built on top of: every base the mesh resolved
+// and handed the recipe as a build argument (`build.on`), and any image a recipe pins by digest
+// itself. Nothing is guessed: a reference that was neither resolved nor written down is not
+// reported.
+//
+// **The resolved bases are the edges.** A recipe reads its base from an argument (`FROM
+// ${RUNTIME_BASE}`), so the digest is never in the file, and a derivation that read files alone
+// recorded no edge for any module on the mesh — which is why nothing knew what a changed base
+// meant to rebuild (novox/hq 04-ISSUES/131).
+func against(within string, manifest catalogue.Manifest, resolved []string) []string {
 	if manifest.Build == nil {
 		return nil
 	}
 	seen := map[string]bool{}
 	var out []string
+	for _, r := range resolved {
+		if r != "" && !seen[r] {
+			seen[r] = true
+			out = append(out, r)
+		}
+	}
 	for _, a := range manifest.Build.Artifacts {
 		if a.Kind != catalogue.ArtifactImage || a.From == "" {
 			continue
@@ -704,40 +726,42 @@ var _ io.Writer = (*stringWriter)(nil)
 // built cannot be built here yet, and the useful sentence names which module is missing — not the
 // one a container runtime produces when a recipe's first line refers to an image nobody has.
 //
-// The order is fixed so two builds of one commit invoke the same command.
+// The order is fixed so two builds of one commit invoke the same command. Returned alongside the
+// arguments is every reference they resolved to, which is what the build stood on.
 func standingOn(ctx context.Context, manifest catalogue.Manifest, held map[string]string,
-	mirror func(ctx context.Context, from, repository string) (string, error)) ([]string, error) {
+	mirror func(ctx context.Context, from, repository string) (string, error)) ([]string, []string, error) {
 	if manifest.Build == nil || len(manifest.Build.On) == 0 {
-		return nil, nil
+		return nil, nil, nil
 	}
 	on := append([]catalogue.BuildsOn{}, manifest.Build.On...)
 	sort.Slice(on, func(i, j int) bool { return on[i].Arg < on[j].Arg })

-	var args []string
+	var args, resolved []string
 	for _, base := range on {
 		if base.Image != "" {
 			// A vendor's image, declared (novox/hq 04-ISSUES/064, ADR 0097). Pinned, because a tag
 			// is what somebody else can move; copied into the mesh's registry, because a build
 			// that reaches a public registry on its own is a build that works sometimes.
 			if base.Arg == "" || base.Module != "" || base.Artifact != "" {
-				return nil, fmt.Errorf(
+				return nil, nil, fmt.Errorf(
 					"%s stands on the image %s, and a base is either a module's artifact or an "+
 						"image — never both — read from one build argument", manifest.Module, base.Image)
 			}
 			if !strings.Contains(base.Image, "@sha256:") {
-				return nil, fmt.Errorf(
+				return nil, nil, fmt.Errorf(
 					"%s stands on the image %q, which is not pinned by digest. A tag is what "+
 						"somebody else can move; name it as <image>@sha256:…", manifest.Module, base.Image)
 			}
 			reference, err := mirror(ctx, base.Image, manifest.Module+"/on-"+strings.ToLower(base.Arg))
 			if err != nil {
-				return nil, fmt.Errorf("%s stands on %s: %w", manifest.Module, base.Image, err)
+				return nil, nil, fmt.Errorf("%s stands on %s: %w", manifest.Module, base.Image, err)
 			}
 			args = append(args, "--build-arg", base.Arg+"="+reference)
+			resolved = append(resolved, reference)
 			continue
 		}
 		if base.Arg == "" || base.Module == "" || base.Artifact == "" {
-			return nil, fmt.Errorf(
+			return nil, nil, fmt.Errorf(
 				"%s says its build stands on something, and does not say all of what: a base "+
 					"needs the module, the artifact, and the build argument the recipe reads it "+
 					"from", manifest.Module)
@@ -745,14 +769,15 @@ func standingOn(ctx context.Context, manifest catalogue.Manifest, held map[strin
 		key := base.Module + "/" + base.Artifact
 		reference, has := held[key]
 		if !has {
-			return nil, fmt.Errorf(
+			return nil, nil, fmt.Errorf(
 				"%s builds on %s, and this mesh has not built it. Build %s first — every module "+
 					"in this toolchain stands on it, so it is the thing to have before anything "+
 					"else", manifest.Module, key, base.Module)
 		}
 		args = append(args, "--build-arg", base.Arg+"="+reference)
+		resolved = append(resolved, reference)
 	}
-	return args, nil
+	return args, resolved, nil
 }

 // compile runs a module's own code through its toolchain, and says where the result is.
@@ -997,3 +1022,31 @@ func instructions(recipe string) []string {
 	flush()
 	return out
 }
+
+// readBy is every repository other than the module's own that this build's recipes read source from,
+// each once and in a fixed order, so two builds of one commit report the same thing the same way.
+func readBy(manifest catalogue.Manifest) []catalogue.ArtifactContext {
+	if manifest.Build == nil {
+		return nil
+	}
+	seen := map[string]bool{}
+	var out []catalogue.ArtifactContext
+	for _, a := range manifest.Build.Artifacts {
+		if a.Context == nil || a.Context.Repository == "" {
+			continue
+		}
+		key := a.Context.Repository + "#" + a.Context.Ref
+		if seen[key] {
+			continue
+		}
+		seen[key] = true
+		out = append(out, *a.Context)
+	}
+	sort.Slice(out, func(i, j int) bool {
+		if out[i].Repository != out[j].Repository {
+			return out[i].Repository < out[j].Repository
+		}
+		return out[i].Ref < out[j].Ref
+	})
+	return out
+}
@@ -180,6 +180,20 @@ func (r Registry) MirrorImage(ctx context.Context, from, repository string) (str
 	if err != nil {
 		return "", err
 	}
+	// **Already held is already mirrored.** A base is named by digest, and a digest this registry
+	// holds under the module's repository is the same bytes whatever upstream would say — so
+	// upstream is not asked. Asked every build, the public hub's anonymous pull limit was reached
+	// on the first merge that rebuilt a whole catalogue (2026-09-28), and every module whose base
+	// lives there failed on a copy it did not need.
+	if strings.HasPrefix(where.reference, "sha256:") {
+		held, err := r.has(ctx, "http://"+r.Address+"/v2/"+repository+"/manifests/"+where.reference, manifestAccept)
+		if err != nil {
+			return "", fmt.Errorf("asking %s whether it holds %s: %w", r.Address, from, err)
+		}
+		if held {
+			return r.Address + "/" + repository + "@" + where.reference, nil
+		}
+	}
 	src := &source{client: r.client()}
 	digest, err := r.copyManifest(ctx, src, where, where.reference, repository)
 	if err != nil {
@@ -103,6 +103,20 @@ func (m *theMeshsRegistry) handler() http.Handler {
 		m.mu.Lock()
 		defer m.mu.Unlock()
 		switch {
+		case r.Method == http.MethodHead && strings.Contains(r.URL.Path, "/manifests/"):
+			// **As strictly as a real registry.** A manifest is answered only in a media type the
+			// caller named; a request with no Accept is answered as if nothing were there. The fake
+			// used to answer regardless, which is why it could not catch a check that asked without
+			// one — and the mesh copied every base again (2026-09-28).
+			if !strings.Contains(r.Header.Get("Accept"), "manifest") && !strings.Contains(r.Header.Get("Accept"), "index") {
+				w.WriteHeader(http.StatusNotFound)
+				return
+			}
+			if _, ok := m.manifests[r.URL.Path[strings.LastIndex(r.URL.Path, "/")+1:]]; ok {
+				w.WriteHeader(http.StatusOK)
+			} else {
+				w.WriteHeader(http.StatusNotFound)
+			}
 		case r.Method == http.MethodHead && strings.Contains(r.URL.Path, "/blobs/"):
 			if _, ok := m.blobs[r.URL.Path[strings.LastIndex(r.URL.Path, "/")+1:]]; ok {
 				w.WriteHeader(http.StatusOK)
@@ -219,3 +233,27 @@ func TestATagBeforeTheDigestIsNotPartOfTheRepository(t *testing.T) {
 		t.Fatalf("got %+v", got)
 	}
 }
+
+// A base this registry already holds by digest is not asked of upstream at all: the public hub
+// limits anonymous pulls, and a catalogue rebuilt on one merge asked it once per module.
+func TestABaseAlreadyHeldIsNotAskedOfUpstream(t *testing.T) {
+	src, indexDigest, _ := anUpstreamRegistry(t)
+	dst := &theMeshsRegistry{blobs: map[string][]byte{}, manifests: map[string][]byte{}}
+	dstServer := httptest.NewServer(dst.handler())
+	defer dstServer.Close()
+	address := strings.TrimPrefix(dstServer.URL, "http://")
+	r := Registry{Address: address, HTTP: src.Client()}
+	host := strings.TrimPrefix(src.URL, "http://")
+	if _, err := r.MirrorImage(context.Background(), host+"/library/thing:latest", "hello-web/server"); err != nil {
+		t.Fatal(err)
+	}
+	// Upstream gone: the pinned base is answered from what the mesh holds.
+	src.Close()
+	reference, err := r.MirrorImage(context.Background(), host+"/library/thing@"+indexDigest, "hello-web/server")
+	if err != nil {
+		t.Fatalf("a base the registry holds was asked of an upstream that is gone: %v", err)
+	}
+	if reference != address+"/hello-web/server@"+indexDigest {
+		t.Fatalf("pinned as %q", reference)
+	}
+}
@@ -122,11 +122,23 @@ func (r Registry) PublishArchive(ctx context.Context, repository string, body []
 	return final, nil
 }

-func (r Registry) has(ctx context.Context, url string) (bool, error) {
+// has is whether this registry already holds what is at that URL.
+//
+// **A manifest HEAD must say what it accepts.** A registry answers a manifest request only in a media
+// type the caller named, and a bare HEAD — no Accept at all — is answered 404 for a manifest it holds
+// perfectly well. Measured against the mesh's own registry (2026-09-28): the same digest answered 200
+// with the manifest media types and 404 without them, so a check written without them concluded the
+// registry held nothing, copied every base again, and exhausted the public hub's pull limit. A blob
+// needs no Accept, which is why this went unnoticed: the same helper was right for blobs and wrong
+// for manifests.
+func (r Registry) has(ctx context.Context, url string, accept ...string) (bool, error) {
 	request, err := http.NewRequestWithContext(ctx, http.MethodHead, url, nil)
 	if err != nil {
 		return false, err
 	}
+	for _, media := range accept {
+		request.Header.Add("Accept", media)
+	}
 	response, err := r.client().Do(request)
 	if err != nil {
 		return false, fmt.Errorf("cannot reach the registry at %s: %w", r.Address, err)
@@ -22,7 +22,7 @@ func TestABaseTheMeshHasNotBuiltIsRefused(t *testing.T) {
 			On: []catalogue.BuildsOn{{Arg: "RUNTIME_BASE", Module: "mesh-tools", Artifact: "runtime"}},
 		},
 	}
-	_, err := standingOn(context.Background(), manifest, map[string]string{}, noMirror)
+	_, _, err := standingOn(context.Background(), manifest, map[string]string{}, noMirror)
 	if err == nil {
 		t.Fatal("a base nothing has built was accepted; the build would have failed on its first line")
 	}
@@ -42,7 +42,7 @@ func TestABaseTheMeshHoldsBecomesABuildArgument(t *testing.T) {
 		},
 	}
 	held := map[string]string{"mesh-tools/runtime": "127.0.0.1:5000/mesh-tools/runtime@sha256:" + strings.Repeat("a", 64)}
-	args, err := standingOn(context.Background(), manifest, held, noMirror)
+	args, _, err := standingOn(context.Background(), manifest, held, noMirror)
 	if err != nil {
 		t.Fatalf("a base this mesh holds was refused: %v", err)
 	}
@@ -54,7 +54,7 @@ func TestABaseTheMeshHoldsBecomesABuildArgument(t *testing.T) {

 // A module naming no base asks for nothing, which is most modules.
 func TestAModuleNamingNoBaseAddsNoArguments(t *testing.T) {
-	args, err := standingOn(context.Background(), catalogue.Manifest{Module: "hello-web", Build: &catalogue.Build{}}, nil, noMirror)
+	args, _, err := standingOn(context.Background(), catalogue.Manifest{Module: "hello-web", Build: &catalogue.Build{}}, nil, noMirror)
 	if err != nil || args != nil {
 		t.Fatalf("a module naming no base produced %v, %v", args, err)
 	}
@@ -66,7 +66,7 @@ func TestAnIncompleteBaseIsRefused(t *testing.T) {
 		Module: "postgres",
 		Build:  &catalogue.Build{On: []catalogue.BuildsOn{{Module: "mesh-tools", Artifact: "runtime"}}},
 	}
-	if _, err := standingOn(context.Background(), manifest, map[string]string{"mesh-tools/runtime": "x"}, noMirror); err == nil {
+	if _, _, err := standingOn(context.Background(), manifest, map[string]string{"mesh-tools/runtime": "x"}, noMirror); err == nil {
 		t.Fatal("a base with no build argument was accepted; nothing would have read it")
 	}
 }
@@ -86,7 +86,7 @@ func TestADeclaredVendorImageIsCopiedInAndHandedToTheRecipe(t *testing.T) {
 		},
 	}
 	var asked []string
-	args, err := standingOn(context.Background(), manifest, nil, func(_ context.Context, from, repository string) (string, error) {
+	args, _, err := standingOn(context.Background(), manifest, nil, func(_ context.Context, from, repository string) (string, error) {
 		asked = append(asked, from+" -> "+repository)
 		return "127.0.0.1:5000/" + repository + "@sha256:" + strings.Repeat("d", 64), nil
 	})
@@ -101,7 +101,7 @@ func TestADeclaredVendorImageIsCopiedInAndHandedToTheRecipe(t *testing.T) {
 	}
 	// Unpinned, it is refused: a tag is what somebody else can move.
 	manifest.Build.On[0].Image = "quay.io/minio/mc:latest"
-	if _, err := standingOn(context.Background(), manifest, nil, noMirror); err == nil || !strings.Contains(err.Error(), "not pinned") {
+	if _, _, err := standingOn(context.Background(), manifest, nil, noMirror); err == nil || !strings.Contains(err.Error(), "not pinned") {
 		t.Fatalf("an unpinned vendor image was accepted: %v", err)
 	}
 }
@@ -151,3 +151,52 @@ func TestARecipeIsReadAsInstructions(t *testing.T) {
 		t.Fatalf("a heredoc line or a continued stage was read as a base: %v", bases)
 	}
 }
+
+// What a build was handed as its bases is what it stood on — recorded, so a changed base knows what
+// to rebuild (novox/hq 04-ISSUES/131). A recipe reads the base from an argument, so nothing else
+// could know.
+func TestTheBasesABuildWasHandedAreWhatItStoodOn(t *testing.T) {
+	manifest := catalogue.Manifest{
+		Module: "gitea",
+		Build: &catalogue.Build{
+			On: []catalogue.BuildsOn{
+				{Arg: "RUNTIME_BASE", Module: "mesh-tools", Artifact: "runtime"},
+				{Arg: "BUILD_BASE", Module: "mesh-tools", Artifact: "build"},
+			},
+			Artifacts: []catalogue.Artifact{{Name: "runtime", Kind: catalogue.ArtifactImage, From: "Dockerfile"}},
+		},
+	}
+	held := map[string]string{
+		"mesh-tools/runtime": "127.0.0.1:5000/mesh-tools/runtime@sha256:" + strings.Repeat("a", 64),
+		"mesh-tools/build":   "127.0.0.1:5000/mesh-tools/build@sha256:" + strings.Repeat("b", 64),
+	}
+	_, resolved, err := standingOn(context.Background(), manifest, held, noMirror)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := against(t.TempDir(), manifest, resolved)
+	if len(got) != 2 || got[0] != held["mesh-tools/build"] || got[1] != held["mesh-tools/runtime"] {
+		t.Fatalf("the bases the build was handed were not what it stood on: %v", got)
+	}
+}
+
+// What a build read besides its module's own repository is the second repository its recipes name,
+// each once: a module that packages source living elsewhere is affected when that source moves.
+func TestWhatABuildReadIsTheRepositoriesItsRecipesName(t *testing.T) {
+	elsewhere := catalogue.ArtifactContext{Repository: "http://forge.internal:20000/novox/mesh-controller.git", Ref: "main"}
+	manifest := catalogue.Manifest{
+		Module: "builder",
+		Build: &catalogue.Build{Artifacts: []catalogue.Artifact{
+			{Name: "server", Kind: catalogue.ArtifactImage, From: "Dockerfile", Context: &elsewhere},
+			{Name: "tools", Kind: catalogue.ArtifactImage, From: "Dockerfile", Context: &elsewhere},
+			{Name: "config", Kind: catalogue.ArtifactArchive, From: "etc"},
+		}},
+	}
+	read := readBy(manifest)
+	if len(read) != 1 || read[0] != elsewhere {
+		t.Fatalf("the repositories this build read are %+v", read)
+	}
+	if readBy(catalogue.Manifest{Module: "gitea", Build: &catalogue.Build{}}) != nil {
+		t.Fatal("a module whose recipes name no other repository read one")
+	}
+}
@@ -59,7 +59,11 @@ func anchorRendering(adopted bool) Rendering {
 			Values: map[string]any{ExposeSetting: map[string]any{"5000": FromEverywhere}}}}},
 		Mesh:       []string{"10.42.0.1"},
 		Foundation: []int{5671},
-		Adopted:    adopted,
+		// What the machine reported faces outside, which every rule in the filter is written
+		// around (novox/hq ADR 0140).
+		OutwardLinks:    []string{"eth0"},
+		TunnelInterface: "mesh0",
+		Adopted:         adopted,
 		// Genesis takes the foundation's modules.
 		Taken: map[string]bool{"postgres": true, "lavinmq": true},
 	}
@@ -575,11 +579,13 @@ func TestAGivenMachineSideReachesTheFilterTheOpeningAndTheConsumer(t *testing.T)
 	}
 	r := Resolution{Node: "anchor", Modules: []Manifest{forge}}
 	with := Rendering{
-		Ports:   map[string]map[int]int{"forge": portsAsThePlanWould(forge, given)},
-		Given:   map[string]map[int]int{"forge": given},
-		Mesh:    []string{"10.77.0.1"},
-		Adopted: true,
-		Taken:   map[string]bool{"forge": true},
+		Ports:           map[string]map[int]int{"forge": portsAsThePlanWould(forge, given)},
+		Given:           map[string]map[int]int{"forge": given},
+		Mesh:            []string{"10.77.0.1"},
+		Adopted:         true,
+		OutwardLinks:    []string{"eth0"},
+		TunnelInterface: "mesh0",
+		Taken:           map[string]bool{"forge": true},
 	}

 	// What the runtime is handed: the machine's own port on the outside, the container's within.
@@ -660,9 +666,11 @@ func TestALongFormPortIsOpenedWhereTheManifestPublishesIt(t *testing.T) {
 	forge := aForge()
 	r := Resolution{Node: "anchor", Modules: []Manifest{forge}}
 	composed, err := r.Compose(Rendering{
-		Ports:   map[string]map[int]int{"forge": portsAsThePlanWould(forge, nil)},
-		Mesh:    []string{"10.77.0.1"},
-		Adopted: true,
+		Ports:           map[string]map[int]int{"forge": portsAsThePlanWould(forge, nil)},
+		Mesh:            []string{"10.77.0.1"},
+		Adopted:         true,
+		OutwardLinks:    []string{"eth0"},
+		TunnelInterface: "mesh0",
 	})
 	if err != nil {
 		t.Fatal(err)
@@ -0,0 +1,48 @@
+package catalogue
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// **The word does not come back through a manifest** (novox/hq ADR 0131). A module that wants
+// messaging wants the mesh's bus, reached through the sdk and named by the `mesh-broker` seat. Naming
+// the old wire protocol asks for the one server being retired, so both directions are refused at the
+// parser — this is judged from the manifest alone, no store needed.
+
+func TestAManifestProvidingAmqpIsRefused(t *testing.T) {
+	raw := []byte(`{"module":"old-broker","version":"1","provides":[{"name":"amqp","scope":"mesh"}]}`)
+	_, err := ParseManifest(raw)
+	if err == nil || !strings.Contains(err.Error(), `provides "amqp", which is not a provision`) {
+		t.Fatalf("a module providing amqp was not refused, or not for the reason: %v", err)
+	}
+}
+
+func TestAManifestRequiringAmqpIsRefused(t *testing.T) {
+	raw := []byte(`{"module":"forwarder","version":"1","requires":["amqp"]}`)
+	_, err := ParseManifest(raw)
+	if err == nil || !strings.Contains(err.Error(), `requires "amqp", which is not a provision`) {
+		t.Fatalf("a module requiring amqp was not refused, or not for the reason: %v", err)
+	}
+}
+
+// And the catalogue as checked out beside this repository names it nowhere — the three modules that
+// did are removed under design 28 task 5.4, not converted.
+func TestNoCatalogueManifestNamesAmqp(t *testing.T) {
+	modules, err := filepath.Glob("../../../mesh-catalog/modules/*/module.json")
+	if err != nil || len(modules) == 0 {
+		t.Skip("the catalogue is not checked out beside this repository")
+	}
+	for _, path := range modules {
+		raw, err := os.ReadFile(path)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if strings.Contains(string(raw), `"amqp"`) {
+			t.Errorf("%s names amqp, which is not a provision (novox/hq ADR 0131)",
+				filepath.Base(filepath.Dir(path)))
+		}
+	}
+}
@@ -0,0 +1,87 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// The mesh's bus is one per mesh, read from the catalogue beside this checkout.
+//
+// **This is step 2's claim, and it is checked here rather than in a bed** (novox/hq ADR 0116):
+// adoption puts the NATS server into the `mesh-broker` seat on a mesh that is already running,
+// and the property that matters is that a second one anywhere is refused *when it is assigned*,
+// not discovered later as two servers holding different halves of the mesh's traffic. A second
+// bus is not a degraded mesh; it is two meshes that both believe they are the one.
+func TestASecondMeshBusAnywhereIsRefusedByName(t *testing.T) {
+	nats := catalogueManifest(t, "nats")
+
+	if _, err := Resolve(shelf(nats), []string{"nats"}, workstation(), World{}); err != nil {
+		t.Fatalf("the bus alone does not resolve: %v", err)
+	}
+
+	elsewhere := World{Held: []Held{{Claim: "mesh-broker", Scope: ScopeMesh,
+		Node: "anchor", Module: "nats"}}}
+	other := workstation()
+	other.Name = "laptop"
+	_, err := Resolve(shelf(nats), []string{"nats"}, other, elsewhere)
+	if err == nil {
+		t.Fatal("a second bus was accepted on another machine")
+	}
+	if !strings.Contains(err.Error(), "mesh-broker") || !strings.Contains(err.Error(), "one per mesh") {
+		t.Fatalf("refused without naming the seat: %v", err)
+	}
+}
+
+// The seat is the server's role, not the product's name (novox/hq ADR 0079). A different
+// implementation of the bus claims the same seat, and the mesh refuses it for the same reason —
+// which is the property that lets the bus be replaced at all.
+func TestTheSeatRefusesADifferentBusToo(t *testing.T) {
+	nats := catalogueManifest(t, "nats")
+	held := World{Held: []Held{{Claim: "mesh-broker", Scope: ScopeMesh,
+		Node: "anchor", Module: "some-other-broker"}}}
+	other := workstation()
+	other.Name = "laptop"
+	if _, err := Resolve(shelf(nats), []string{"nats"}, other, held); err == nil {
+		t.Fatal("the seat admitted a second holder because the module's name differed")
+	}
+}
+
+// The old broker is gone from the catalogue (novox/hq ADR 0131, design 28 task 5.4), so it is no
+// longer a fixture here. That two eligible holders stand beside each other with one on record is
+// pinned in holdings_test.go against manifests this package owns.
+
+// **A seat and the interface it delivers are different names, and renaming one must not rename
+// the other** (novox/hq ADR 0118). This nearly went wrong: the seats were renamed to the `mesh-*`
+// prefix, and a blanket search-and-replace also renamed `npm-package-registry` and `git` where
+// they are *provisions* — which a consumer requires and a provider offers. The tests failed with
+// "the package registry is served on <nil>", which does not say "you renamed an interface".
+func TestRenamingASeatDidNotRenameTheInterfaceItDelivers(t *testing.T) {
+	for _, pair := range []struct{ seat, delivers string }{
+		{"git", "git"},
+		{"npm-package-registry", "npm-package-registry"},
+		{"the-artifact-store", "artifact-store"},
+		{"mesh-store", "postgres-database"},
+		{"mesh-broker", "mesh-bus"},
+	} {
+		s, known := SeatNamed(pair.seat)
+		if !known {
+			t.Fatalf("%q is not a seat", pair.seat)
+		}
+		if s.Delivers != pair.delivers {
+			t.Errorf("the %s seat delivers %q, expected %q — renaming the seat moved the "+
+				"interface with it, and every consumer requiring it would stop resolving",
+				pair.seat, s.Delivers, pair.delivers)
+		}
+		// **Three of these deliberately share a name with what they deliver**, and that is not an
+		// incomplete rename. Renaming a seat that delivers a provision cascades to every consumer
+		// requiring it, with a mesh-wide window where a holder stops resolving mid-flight — so the
+		// trunk deferred exactly those three (novox/hq ADR 0121) while renaming the node-scoped ones.
+		// What this test is for is the other direction: that renaming a seat never moves the
+		// interface, which once produced "the package registry is served on <nil>".
+	}
+}
+
+// A manifest written against an old seat name is told what it became rather than refused as
+// unknown. **That map is the controller's store now, not this package** (novox/hq ADR 0122): a
+// rename is a row, so the courtesy survives a rename nobody recompiled for. Checked where the
+// table is read, not here, where there is no longer a hardcoded list to check against.
@@ -153,6 +153,26 @@ func (b *Build) problems(module string) []string {
 					"%s: %q is a bundle and says no language, so nothing can choose a compiler "+
 						"for it", module, a.Name))
 			}
+			// **A system, for a language that compiles to a binary** (novox/hq ADR 0142). A binary
+			// is pinned to one operating system at link time so a host refuses to touch a machine
+			// it was not built for (novox/hq ADR 0005); an artifact that says nothing would be
+			// compiled for whatever the build machine happened to be, which reads as portable and
+			// is not.
+			if compiled := compilesToABinary(a.Language); compiled && strings.TrimSpace(a.System) == "" {
+				problems = append(problems, fmt.Sprintf(
+					"%s: %q is compiled to a binary and says no system, so it would be built for "+
+						"whatever the build machine happens to be. Declare one artifact per "+
+						"system: %s", module, a.Name, spokenSystems()))
+			} else if !compiled && strings.TrimSpace(a.System) != "" {
+				problems = append(problems, fmt.Sprintf(
+					"%s: %q names the system %q and is written in %q, which compiles to code that "+
+						"runs anywhere — a system that decides nothing reads as though it did",
+					module, a.Name, a.System, a.Language))
+			} else if compiled && !knownSystem(a.System) {
+				problems = append(problems, fmt.Sprintf(
+					"%s: %q is built for %q, and a system is %s",
+					module, a.Name, a.System, spokenSystems()))
+			}
 		} else {
 			if a.From == "" {
 				problems = append(problems, fmt.Sprintf(
@@ -193,3 +213,42 @@ func oneOrOther(n int) string {
 	}
 	return "them"
 }
+
+// Systems the mesh builds binaries for, which is the set a host may be pinned to (novox/hq ADR 0005).
+//
+// **A closed list, and the host's own, not the compiler's.** These are not the values a Go toolchain
+// would call an operating system — the difference between two of them is a C library, not a kernel.
+// They are what a machine reports itself to be and what a host is linked to refuse, so the list that
+// matters is the one the host understands.
+var systems = []string{"alpine", "android", "arch"}
+
+// knownSystem is whether the mesh builds for it.
+func knownSystem(system string) bool {
+	want := strings.ToLower(strings.TrimSpace(system))
+	for _, s := range systems {
+		if s == want {
+			return true
+		}
+	}
+	return false
+}
+
+// spokenSystems is the list as a refusal says it, so a reader is one edit from right.
+func spokenSystems() string {
+	return strings.Join(systems, ", ")
+}
+
+// compilesToABinary is whether this language's bundle is a binary for one operating system rather
+// than code that runs wherever its interpreter does.
+//
+// **Asked of the language, not of the artifact.** A module says what it is written in; what that
+// implies is the mesh's to know, exactly as the compiler is (novox/hq ADR 0142). Asking the artifact
+// would let two artifacts in one language disagree about whether they are portable.
+func compilesToABinary(language string) bool {
+	switch strings.ToLower(strings.TrimSpace(language)) {
+	case "go":
+		return true
+	default:
+		return false
+	}
+}
@@ -0,0 +1,82 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// bundleFor is a manifest whose one artifact is a bundle in the given language and system.
+func bundleFor(language, system string) Manifest {
+	return Manifest{Module: "a-component", Build: &Build{Artifacts: []Artifact{
+		{Name: "binary", Kind: ArtifactBundle, Language: language, System: system},
+	}}}
+}
+
+func problemsOf(t *testing.T, m Manifest) string {
+	t.Helper()
+	return strings.Join(m.Build.problems(m.Module), "\n")
+}
+
+// **A language that compiles to a binary must say which system.**
+//
+// A binary is pinned to one operating system at link time, so a host refuses to touch a machine it
+// was not built for. An artifact that says nothing would be compiled for whatever the build machine
+// happened to be — which reads as portable and is not, and is the fault this check exists for.
+func TestABinaryMustSayWhichSystemItIsFor(t *testing.T) {
+	got := problemsOf(t, bundleFor("go", ""))
+	if !strings.Contains(got, "says no system") {
+		t.Fatalf("a compiled bundle with no system was accepted:\n%s", got)
+	}
+	// And the refusal names what it could have said, so a reader is one edit from right.
+	for _, system := range []string{"alpine", "android", "arch"} {
+		if !strings.Contains(got, system) {
+			t.Fatalf("the refusal does not name %q as a choice:\n%s", system, got)
+		}
+	}
+}
+
+func TestABinaryThatNamesASystemIsAccepted(t *testing.T) {
+	if got := problemsOf(t, bundleFor("go", "arch")); got != "" {
+		t.Fatalf("a compiled bundle naming a system was refused:\n%s", got)
+	}
+}
+
+// A system the mesh does not build for is refused where it is written. These are the host's own
+// names, not a compiler's: the difference between two of them is a C library rather than a kernel,
+// so a value that looks like an operating system to a toolchain is still wrong here.
+func TestASystemTheMeshDoesNotBuildForIsRefused(t *testing.T) {
+	for _, wrong := range []string{"linux", "debian", "darwin"} {
+		got := problemsOf(t, bundleFor("go", wrong))
+		if !strings.Contains(got, "and a system is") {
+			t.Fatalf("%q was accepted as a system:\n%s", wrong, got)
+		}
+	}
+}
+
+// **And a language that runs anywhere must not name one.** A system that decides nothing reads as
+// though it did, which is the same fault as a restriction that restricts nothing (novox/hq ADR 0045).
+func TestAPortableBundleMayNotNameASystem(t *testing.T) {
+	got := problemsOf(t, bundleFor("typescript", "arch"))
+	if !strings.Contains(got, "runs anywhere") {
+		t.Fatalf("a portable bundle was allowed to name a system:\n%s", got)
+	}
+}
+
+func TestAPortableBundleNamingNoSystemIsAccepted(t *testing.T) {
+	if got := problemsOf(t, bundleFor("typescript", "")); got != "" {
+		t.Fatalf("an ordinary bundle was refused:\n%s", got)
+	}
+}
+
+// One component, one artifact per system: the shape the mesh's own binaries are declared in, and the
+// reason the target is the artifact's rather than the recipe's.
+func TestOneArtifactPerSystemIsAccepted(t *testing.T) {
+	m := Manifest{Module: "the-host", Build: &Build{Artifacts: []Artifact{
+		{Name: "arch", Kind: ArtifactBundle, Language: "go", System: "arch"},
+		{Name: "alpine", Kind: ArtifactBundle, Language: "go", System: "alpine"},
+		{Name: "android", Kind: ArtifactBundle, Language: "go", System: "android"},
+	}}}
+	if got := problemsOf(t, m); got != "" {
+		t.Fatalf("one artifact per system was refused:\n%s", got)
+	}
+}
@@ -0,0 +1,47 @@
+package catalogue
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// TestEveryCatalogueManifestParses runs the real catalogue through the real gate.
+//
+// Not a fixture: the point is whether the manifests as written are accepted by the control plane that
+// will read them, and a copy of one manifest proves nothing about the other seventy-one.
+func TestEveryCatalogueManifestParses(t *testing.T) {
+	root := os.Getenv("MESH_CATALOGUE")
+	if root == "" {
+		t.Skip("set MESH_CATALOGUE to a catalogue checkout to run this")
+	}
+	found, err := filepath.Glob(filepath.Join(root, "modules", "*", "module.json"))
+	if err != nil || len(found) == 0 {
+		t.Fatalf("no manifests under %s: %v", root, err)
+	}
+	named, routed := 0, 0
+	for _, p := range found {
+		raw, err := os.ReadFile(p)
+		if err != nil {
+			t.Fatalf("%s: %v", p, err)
+		}
+		m, err := ParseManifest(raw)
+		if err != nil {
+			t.Errorf("%s: %v", filepath.Base(filepath.Dir(p)), err)
+			continue
+		}
+		for _, l := range m.Listens {
+			if l.Name != "" {
+				named++
+			}
+		}
+		for port := range RoutedPorts(m) {
+			_ = port
+			routed++
+		}
+	}
+	t.Logf("%d manifests, %d named endpoints, %d routed endpoints resolved", len(found), named, routed)
+	if named == 0 {
+		t.Fatal("no endpoint in the catalogue is named, so this proved nothing")
+	}
+}
@@ -0,0 +1,71 @@
+package catalogue
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+// **A machine trusts the mesh's authority because a module put its root there** (novox/hq ADR
+// 0147, issue 129). The module carries a shell script and a unit, and both are worthless unless
+// the mesh fills in where the authority is — which is the one thing about it the manifest cannot
+// state, because the authority's address is a fact about the mesh and not about the module.
+//
+// So what is checked here is the rendering, not the parsing: the script the machine will run
+// names the authority it was bound to, and the unit runs that script both ways. The verification
+// itself — a plain client trusting an internal name on a machine holding this, and failing on one
+// that does not — is the lab's, and cannot be had here.
+func TestCaTrustRendersTheAuthorityItWasBoundTo(t *testing.T) {
+	raw, err := os.ReadFile("../../../mesh-catalog/modules/ca-trust/module.json")
+	if err != nil {
+		t.Skipf("the catalogue is not beside this checkout: %v", err)
+	}
+	m, err := ParseManifest(raw)
+	if err != nil {
+		t.Fatalf("the trust module does not parse:\n%v", err)
+	}
+
+	r := Resolution{
+		Node:    "workstation",
+		Modules: []Manifest{m},
+		Needs: []Needed{{
+			Name: "internal-acme-ca", From: "anchor", At: "anchor.internal", For: "ca-trust",
+			Serves: map[string]any{
+				"port": float64(9000), "path": "/acme/acme/directory", "roots": "/roots.pem",
+			},
+		}},
+	}
+	out, err := r.Declaration(Rendering{})
+	if err != nil {
+		t.Fatalf("the trust module could not be composed for a machine: %v", err)
+	}
+
+	script := fileNamed(out, "ca-trust.anchor")
+	if script == nil {
+		t.Fatalf("nothing writes the script the unit runs: %v", out)
+	}
+	body, _ := script["content"].(string)
+	if !strings.Contains(body, "https://anchor.internal:9000/roots.pem") {
+		t.Errorf("the script does not fetch from the authority it was bound to:\n%s", body)
+	}
+	if script["mode"] != "0755" {
+		t.Errorf("the script is written %v, which systemd cannot execute", script["mode"])
+	}
+
+	unit := fileNamed(out, "ca-trust.unit")
+	if unit == nil {
+		t.Fatalf("no unit: %v", out)
+	}
+	text, _ := unit["content"].(string)
+	// Both halves. A unit that only installs the anchor leaves a machine trusting an authority
+	// nobody assigned it to any more, which is the half issue 129 asked for by name.
+	for _, want := range []string{
+		"ExecStart=" + script["path"].(string) + " install",
+		"ExecStop=" + script["path"].(string) + " remove",
+		"RemainAfterExit=yes",
+	} {
+		if !strings.Contains(text, want) {
+			t.Errorf("the unit does not say %q:\n%s", want, text)
+		}
+	}
+}
@@ -97,10 +97,43 @@ type Rendering struct {
 	// compose it a second time.
 	Suffix string

+	// BusUsers is the mesh's composed user list, for the module holding `mesh-broker`. Empty on
+	// every other node, and on this one until the controller has composed it.
+	//
+	// **Only the users, never the server's own settings**: those are the module's, in its image and
+	// its mounts (Manifest.BusUsers).
+	BusUsers string
+	// BusMembership is this machine's membership for the bus the mesh is moving to, sealed to it
+	// (design 28, task 5.2). Empty for a machine not being moved. Written as a file the host reads
+	// after the declaration has applied, so the bus it names is standing before the machine leaves
+	// the one it is on.
+	BusMembership string
+
+	// MeshRange is the private network's CIDR (the range node addresses are allocated from), for a
+	// module that must name the whole mesh rather than one machine — an intrusion filter that must
+	// never ban a tunnel peer, say. A per-mesh value the module cannot know, so it is carried here
+	// and offered as ${machine:mesh-range}, the same way one machine's address is.
+	MeshRange string
+
+	// Accounts is each machine's operator account, by the same internal name Names uses (novox/hq
+	// to-be 29). What an ssh Host block's `User` line is composed from; empty for a machine no
+	// operator account is known on.
+	Accounts map[string]string
+
 	// Kept is every operator-sealed secret in the mesh, for a module that `keeps` them. Nil when
 	// nothing on this node keeps them, or the mesh has no operator key.
 	Kept *KeptExport

+	// OutwardLinks is the links this machine reported as facing outside it, which the filter is
+	// written around (novox/hq ADR 0140). Empty means the machine has not said, and the mesh
+	// composes no filter for it rather than writing a rule around a link with no name.
+	OutwardLinks []string
+
+	// TunnelInterface is the interface the mesh's private network runs on, named here rather than
+	// imported because the overlay package rests on this one. Traffic arriving on it is the mesh's,
+	// not this machine's own guest, so the filter admits it only by a rule.
+	TunnelInterface string
+
 	// Foundation is the ports the mesh itself needs reachable on every machine, which no module
 	// declares because the foundation is not a module (novox/hq 04-ISSUES/051 and 052). The broker
 	// is the one that matters: a machine dials it to enrol, and a firewall derived only from
@@ -220,9 +253,23 @@ func (r Resolution) Compose(with Rendering) (Composed, error) {
 	if err != nil {
 		return Composed{}, err
 	}
+	if with.BusMembership != "" {
+		// The machine's own, not any module's: how it reaches the mesh from now on. Sealed like a
+		// secret and placed where the host looks for exactly this (design 28, task 5.2).
+		resources = append(resources, map[string]any{
+			"id": BusMembershipID(), "type": "file", "path": BusMembershipPath,
+			"sealed": with.BusMembership, "mode": "0600",
+		})
+	}
 	return Composed{Resources: resources, Owner: owner}, nil
 }

+// BusMembershipID names the resource carrying a machine's membership for the new bus, and
+// BusMembershipPath is where the host reads it — the same constant on both sides.
+func BusMembershipID() string { return "bus-membership" }
+
+const BusMembershipPath = "/var/lib/mesh/membership-next.json"
+
 func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[string]any, error) {
 	// Every manifest is placed first (novox/hq ADR 0112): the maps naming where its bindings,
 	// credentials and contributions land are resolved against this node's directories, so every
@@ -308,7 +355,21 @@ func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[stri
 	if err != nil {
 		return nil, err
 	}
-	filtering := AsNftables(rules, with.Mesh, r.PublicDomain != "", with.Foundation)
+	// **A machine that has not said which links face outside is sent no filter** (novox/hq ADR
+	// 0140). The whole chain is written around those links: with none, the rule that lets this
+	// machine's own guests keep working would name an empty set, which nftables refuses, and a rule
+	// set that does not load is a machine filtering nothing while its unit reports success. Refused
+	// here, where a person reads it, rather than on the machine — and the machine keeps the filter
+	// it already has.
+	if filters := r.filtersHere(); filters != "" && len(with.OutwardLinks) == 0 {
+		return nil, fmt.Errorf(
+			"%s cannot be sent a filter: it has not reported which of its links face outside, and "+
+				"every rule in the chain is written around them. It reports that on each apply; "+
+				"`node show %s` says whether it has. Until then %s is not sent, and the machine "+
+				"keeps the filter it has", r.Node, r.Node, filters)
+	}
+	filtering := AsNftables(rules, with.Mesh, r.PublicDomain != "", with.Foundation,
+		with.OutwardLinks, with.TunnelInterface)

 	var out []map[string]any
 	for _, m := range r.Modules {
@@ -339,6 +400,12 @@ func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[stri
 				"content": filtering, "mode": "0600",
 			})
 		}
+		// The node's fail2ban jails, composed from every module it runs (novox/hq to-be 31), written
+		// where the intrusion-prevention holder owns them. Like the rule set above: gathered from all
+		// modules, written by the one that holds the role.
+		if j := m.Jailing; j != nil {
+			first = append(first, jailsInto(r.Modules, j)...)
+		}
 		if c := m.Certificate; c != nil {
 			if with.Certificate == "" {
 				// Asked for and not issued. Refused rather than skipped: a module that serves TLS
@@ -359,6 +426,35 @@ func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[stri
 				})
 			}
 		}
+		if m.BusUsers != "" {
+			// **The claim authorises it, not the field.** This file holds every user's password
+			// hash, so a module that could ask for it could read every credential on the bus.
+			// Checked from this manifest alone, which is the cheapest check there is: whether some
+			// other module also claims the seat is resolution's business elsewhere, and one holder
+			// mesh-wide is already guaranteed.
+			if !m.ClaimsSeat("mesh-broker") {
+				return nil, fmt.Errorf(
+					"%s asks for the mesh's user list and does not claim mesh-broker. That file "+
+						"holds every user's password hash, so the seat is what authorises it",
+					m.Module)
+			}
+			if with.BusUsers == "" {
+				// Asked for and not composed. Refused rather than skipped, for the reason a
+				// certificate is: a bus with no user list refuses every connection in the mesh, and
+				// an empty file would look like a configuration problem on the machine.
+				return nil, fmt.Errorf(
+					"%s holds mesh-broker and the mesh composed no user list, so the bus would "+
+						"refuse every connection", m.Module)
+			}
+			first = append(first, map[string]any{
+				"id": BusUsersID(), "type": "file", "path": m.BusUsers,
+				"content": with.BusUsers,
+				// Readable by the server and nothing else. Hashes rather than passwords, so this is
+				// not a set of working credentials — but a list of every user in the mesh is worth
+				// keeping to the one process that needs it.
+				"mode": "0600",
+			})
+		}
 		for _, name := range sortedKeys(m.OwnSecrets) {
 			sealed := with.Needed[m.Module][name]
 			if sealed == "" {
@@ -545,12 +641,15 @@ func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[stri
 		// (novox/hq ADR 0112) — resolved once per module, named by ${dir:…} from any resource.
 		dirs := dirsFor(m, with)
 		// And the machine underneath, which no binding of its own can tell it.
-		thisMachine := machineFacts(r, with.Names)
+		thisMachine := machineFacts(r, with.Names, with.MeshRange)

 		// Which of this module's files carry a secret, for the rule that a container may not read
 		// one of them as its environment without saying so (ADR 0086, issue 041).
 		secretFiles := secretFilesOf(resources)

+		// Which of this module's resources its preparation runs before, if it prepares anything.
+		prepareBefore := preparationTarget(m)
+
 		for _, unsettled := range resources {
 			resource, err := ApplySettings(unsettled, with.Settings[m.Module])
 			if err != nil {
@@ -636,6 +735,18 @@ func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[stri
 			if renamed := reflectsRenamed(m.Module, resource["reload-on"]); renamed != nil {
 				copied["reload-on"] = renamed
 			}
+			// **A version prepares its state before it runs** (novox/hq ADR 0135). Derived from the
+			// module's own resource rather than declared beside it: what prepares the state is the
+			// module's own code, so what it is given has to be what that code is given — and a
+			// second resource written by hand is a second copy to drift from the first. Placed
+			// immediately before it, because a run-once step stops everything the declaration
+			// places after it (ADR 0052), which is how a version whose preparation failed does not
+			// serve.
+			if prepareBefore != "" && fmt.Sprint(resource["id"]) == prepareBefore {
+				step := prepared(copied)
+				owner[fmt.Sprint(step["id"])] = m.Module
+				out = append(out, step)
+			}
 			owner[fmt.Sprint(copied["id"])] = m.Module
 			out = append(out, copied)
 		}
@@ -644,7 +755,7 @@ func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[stri
 		// plane's; making a name resolve is the module's software. Emitted as ordinary files under
 		// this module's name, so they are applied, reported and removed exactly as anything else
 		// it declares.
-		given, err := FactsInto(m, r, with.Names, with.Machines, with.Suffix)
+		given, err := FactsInto(m, r, with.Names, with.Machines, with.Accounts, with.Suffix)
 		if err != nil {
 			return nil, err
 		}
@@ -765,6 +876,17 @@ func mapping(written string) (outer, inner int, address string, ok bool) {
 	return outer, inner, strings.Join(parts[:len(parts)-2], ":"), true
 }

+// filtersHere is the module on this node that loads the machine's packet filter, or empty when none
+// does. Named rather than counted: a refusal that says which module is one step from acted on.
+func (r Resolution) filtersHere() string {
+	for _, m := range r.Modules {
+		if m.Filtering != nil {
+			return m.Module
+		}
+	}
+	return ""
+}
+
 // Rules is the rule set this node's filter is derived from: every module's listens, what was
 // computed for this machine, and each module's per-node exposure. The same answer whether the node
 // is adopted or converged — the one loads it as a filter, the other declares it as openings.
@@ -775,6 +897,35 @@ func (r Resolution) Rules(with Rendering) ([]Rule, error) {
 		if err != nil {
 			return nil, err
 		}
+		// And how far each endpoint reaches, which says the same thing to the filter and more
+		// besides (novox/hq ADR 0138). Folded in here rather than beside: the filter has one
+		// question — from where — and a reach answers it, so giving it two inputs would let them
+		// disagree. Reaches refuses a port that both name, so this cannot silently prefer one.
+		reaches, err := Reaches(m, with.Settings[m.Module])
+		if err != nil {
+			return nil, err
+		}
+		// **Only for an endpoint the proxy does not serve.** A routed endpoint's port is how the
+		// proxy reaches it and nothing else (ADR 0045), so `public` there asks for a public name and
+		// says nothing about the port — opening it to the world as well would undo the arrangement
+		// the proxy exists for, and would silently reopen a port an operator had narrowed.
+		//
+		// Found by trying to express a real module: one whose routed name must be public and whose
+		// machine-side port must not be. Under one value for both, there was no way to say it.
+		routed := RoutedPorts(m)
+		for port, reach := range reaches {
+			if routed[port] {
+				continue
+			}
+			source, ok := FilterSource(reach)
+			if !ok {
+				return nil, fmt.Errorf("%s: %q is not a reach the filter can read", m.Module, reach)
+			}
+			if e == nil {
+				e = map[int]string{}
+			}
+			e[port] = source
+		}
 		if e != nil {
 			exposure[m.Module] = e
 		}
@@ -943,7 +1094,16 @@ func (r Resolution) contributions(settings SettingsBy, grants []Grant,
 			if err != nil {
 				return nil, fmt.Errorf("%s contributing to %s: %w", m.Module, to, err)
 			}
-			composeName(values, r.PublicDomain, r.At)
+			reaches, err := Reaches(m, settings[m.Module])
+			if err != nil {
+				return nil, fmt.Errorf("%s contributing to %s: %w", m.Module, to, err)
+			}
+			blocks, err := Endpoints(m, settings[m.Module])
+			if err != nil {
+				return nil, fmt.Errorf("%s contributing to %s: %w", m.Module, to, err)
+			}
+			portOfEndpoint(values, endpointPorts(m))
+			composeName(values, r.PublicDomain, r.At, reaches, endpointPorts(m), blocks)
 			out[to] = append(out[to], Contribution{From: m.Module, Values: values})
 		}
 		// Several contributions to one requirement (ADR 0094's sibling for `contributes`): an
@@ -957,7 +1117,16 @@ func (r Resolution) contributions(settings SettingsBy, grants []Grant,
 				if err != nil {
 					return nil, fmt.Errorf("%s contributing %s to %s: %w", m.Module, local, to, err)
 				}
-				composeName(values, r.PublicDomain, r.At)
+				reaches, err := Reaches(m, settings[m.Module])
+				if err != nil {
+					return nil, fmt.Errorf("%s contributing %s to %s: %w", m.Module, local, to, err)
+				}
+				blocks, err := Endpoints(m, settings[m.Module])
+				if err != nil {
+					return nil, fmt.Errorf("%s contributing %s to %s: %w", m.Module, local, to, err)
+				}
+				portOfEndpoint(values, endpointPorts(m))
+				composeName(values, r.PublicDomain, r.At, reaches, endpointPorts(m), blocks)
 				out[to] = append(out[to], Contribution{From: m.Module, Values: values})
 			}
 		}
@@ -988,10 +1157,44 @@ func (r Resolution) contributions(settings SettingsBy, grants []Grant,
 // the running mesh keeps serving the full names it has. And a labelled contribution on a node with
 // no public domain composes nothing — there is nothing to join it to — which reads downstream as a
 // route that named no host, the same as it would have before this existed.
-func composeName(values map[string]any, publicDomain, internalDomain string) {
+func composeName(values map[string]any, publicDomain, internalDomain string, reaches map[int]string,
+	ports map[string]int, blocks map[string]Endpoint) {
 	if values == nil {
 		return
 	}
+	// **The subdomain an assignment gave this endpoint**, before the name is joined (novox/hq ADR
+	// 0138). The module contributes a label because it names its own parts; an assignment may say a
+	// different one, because where a thing lives under a domain is the operator's to choose and used
+	// to require editing the module to change.
+	if name, ok := values[RouteEndpoint].(string); ok {
+		if ep, said := blocks[strings.TrimSpace(name)]; said && ep.Label != "" {
+			values["label"] = ep.Label
+		}
+	}
+	// **How far the endpoint this route serves reaches decides which names exist** (novox/hq ADR
+	// 0138). Both were composed whenever the node had both domains, so every routed module got a
+	// public name and an internal one whether anybody wanted them or not — and a certificate for
+	// each, because the proxy certifies the names it is given.
+	//
+	// Joined by the port: a route entry names the port it serves and the module declares a listen on
+	// it. An entry with no port is not an endpoint's route but a rule about a name — a path-level
+	// refusal shadowing another route — and it inherits whatever that route's names turned out to
+	// be, which is why it is left alone here.
+	//
+	// Nothing said is both names, as before. That is what keeps every mesh already running identical
+	// until an assignment speaks.
+	wantPublic, wantInternal := true, true
+	if port, ok := endpointPortOf(values, ports); ok {
+		if reach, said := reaches[port]; said {
+			wantPublic, wantInternal = WantsPublicName(reach), WantsInternalName(reach)
+		}
+	}
+	if !wantPublic {
+		publicDomain = ""
+	}
+	if !wantInternal {
+		internalDomain = ""
+	}
 	if _, already := values["name"]; already {
 		// A full name was given rather than a label. Left as-is: this is the legacy shape, and the
 		// point of the label is to not have to write the full name — a contribution that wrote both
@@ -1538,3 +1741,130 @@ func atMachinePort(serves map[string]any, module string, ports map[string]map[in
 func AtPublishedPort(values map[string]any, module string, published map[int]int) map[string]any {
 	return atMachinePort(values, module, map[string]map[int]int{module: published})
 }
+
+// PreparationArgument is how the mesh asks a module to prepare its state: one word, to the module's
+// own program, whatever that program is (novox/hq ADR 0135).
+//
+// **One word for every kind of module.** A module built as a Go binary receives it as its argument;
+// one built as a bundle receives it through the runtime, whose entry takes the same word. So the
+// mesh has one way of asking and a module has one way of answering, and neither learns the other's
+// shape.
+const PreparationArgument = "prepare"
+
+// preparationTarget is the resource a module's preparation runs before: its own workload.
+//
+// The first container carrying an artifact this module built, and not itself a step — that is the
+// thing that runs the module's code, and therefore the thing whose state must be ready. Empty when
+// the module prepares nothing, or when nothing it declares could run its code.
+//
+// **A module with two own workloads gates the first of them.** Five modules in the catalogue declare
+// more than one container of their own, none of them preparing anything today. If one ever does and
+// its second workload shares the state, the gate is in front of the first — stated here because the
+// alternative is a field asking an author to restate what the mesh can see.
+func preparationTarget(m Manifest) string {
+	if !m.Prepares {
+		return ""
+	}
+	for _, r := range m.Resources {
+		if fmt.Sprint(r["type"]) != "container" || !ownArtifact(r, m.Module) {
+			continue
+		}
+		if once, _ := r["run-once"].(bool); once {
+			continue
+		}
+		return fmt.Sprint(r["id"])
+	}
+	return ""
+}
+
+// ownArtifact is whether a resource runs something this module built, in either spelling a manifest
+// may be in: naming the artifact, before a build resolved it, or carrying the reference a build
+// recorded — this mesh's own store, under this module's name.
+func ownArtifact(resource map[string]any, module string) bool {
+	if named, _ := resource["artifact"].(string); named != "" {
+		return true
+	}
+	image, _ := resource["image"].(string)
+	return strings.HasPrefix(image, ArtifactStoreScheme+module+"/")
+}
+
+// prepared is the module's own resource as the step that prepares its state: the same image, the same
+// context, run to completion with the mesh's preparation argument.
+//
+// Three things are taken away rather than copied, each because the step runs while the version it
+// prepares for is still running. A published port cannot be bound twice, and a step that tried would
+// fail for a reason that has nothing to do with the state. A fixed address cannot be held twice, for
+// the same reason. And a cadence is what a step is the opposite of: a container runs once and gates,
+// or on a schedule, or stays up, never two (ADR 0053).
+func prepared(from map[string]any) map[string]any {
+	step := map[string]any{}
+	for k, v := range from {
+		step[k] = v
+	}
+	// **A hyphen, not a dot.** A resource's id is `<module>.<its own id>`, and a module's name may
+	// itself contain a dot (`novox.be`), so the module is everything before the *last* dot — which
+	// only works if what the mesh derives adds no dot of its own.
+	step["id"] = fmt.Sprint(from["id"]) + "-prepare"
+	step["name"] = fmt.Sprint(from["name"]) + "-prepare"
+	step["run-once"] = true
+	step["args"] = []any{PreparationArgument}
+	delete(step, "ports")
+	delete(step, "ip")
+	delete(step, "schedule")
+	delete(step, "reload-on")
+	return step
+}
+
+// endpointPortOf is the port the endpoint a route serves listens on: looked up by the name the route
+// gives, or read from the port it repeats (novox/hq ADR 0138).
+//
+// `ports` maps this module's endpoint names to their ports, computed once per module rather than
+// re-scanned per contribution.
+func endpointPortOf(values map[string]any, ports map[string]int) (int, bool) {
+	if name, ok := values[RouteEndpoint].(string); ok {
+		if port, found := ports[strings.TrimSpace(name)]; found {
+			return port, true
+		}
+	}
+	return asPort(values["port"])
+}
+
+// endpointPorts is a module's endpoint names against the ports they listen on.
+func endpointPorts(m Manifest) map[string]int {
+	out := map[string]int{}
+	for _, l := range m.Listens {
+		if name := strings.TrimSpace(l.Name); name != "" {
+			out[name] = l.Port
+		}
+	}
+	return out
+}
+
+// portOfEndpoint fills in the port of the endpoint a contribution names, in place.
+//
+// **A contribution that names an endpoint must still carry that endpoint's port**, because everything
+// downstream reads the port: the provider is told where to reach the consumer, and the machine-side
+// redirection that turns a declared port into the number the machine published is keyed on it
+// (atMachinePort). A route that named only its endpoint left the proxy with no port at all, and a
+// proxy with no port has nothing to dial.
+//
+// Found before it shipped and after the catalogue had already been changed to name endpoints — the
+// manifests were merged and the mesh had not yet picked them up, so nothing was broken yet. The
+// declared port, not the machine one: the redirection happens later and is keyed on the declared
+// number, so filling in the machine port here would be redirected a second time or not at all.
+func portOfEndpoint(values map[string]any, ports map[string]int) {
+	if values == nil {
+		return
+	}
+	if _, already := values["port"]; already {
+		// A route that says both is its own answer; the older shape repeated the port and is still read.
+		return
+	}
+	name, ok := values[RouteEndpoint].(string)
+	if !ok {
+		return
+	}
+	if port, found := ports[strings.TrimSpace(name)]; found {
+		values["port"] = port
+	}
+}
@@ -0,0 +1,80 @@
+package catalogue
+
+import "testing"
+
+// The mesh's user list reaches the module holding the bus, and nothing else.
+//
+// Three refusals and one delivery, because each of the refusals would be silent in a different way:
+// a module that asked and was given it could read every credential on the bus; a bus given an empty
+// file refuses every connection in the mesh and looks like a machine problem; and a bus that never
+// asked gets nothing rather than a file it does not read.
+func TestTheMeshsUserListGoesOnlyToTheModuleHoldingTheBus(t *testing.T) {
+	theBus := func() Manifest {
+		return Manifest{
+			Module: "nats", Version: "1",
+			Claims:    []Claim{{Name: "mesh-broker", Scope: ScopeMesh}},
+			BusUsers:  "/var/lib/nats-module/conf/accounts.conf",
+			Resources: []map[string]any{},
+		}
+	}
+
+	on := func(t *testing.T, m Manifest, with Rendering) ([]map[string]any, error) {
+		t.Helper()
+		return Resolution{Node: "anchor", Modules: []Manifest{m}}.Declaration(with)
+	}
+
+	t.Run("the holder is given it", func(t *testing.T) {
+		resources, err := on(t, theBus(), Rendering{BusUsers: "accounts { MESH { users = [] } }"})
+		if err != nil {
+			t.Fatal(err)
+		}
+		// Prefixed with the module it came from, like every resource: two modules may reasonably
+		// both call something "config", and without the prefix the second would silently replace
+		// the first.
+		var found map[string]any
+		for _, r := range resources {
+			if r["id"] == "nats."+BusUsersID() {
+				found = r
+			}
+		}
+		if found == nil {
+			t.Fatalf("the bus was given no user list: %+v", resources)
+		}
+		if found["path"] != "/var/lib/nats-module/conf/accounts.conf" {
+			t.Errorf("written to %v rather than where the module asked", found["path"])
+		}
+		if found["mode"] != "0600" {
+			t.Errorf("mode %v: a list of every user in the mesh belongs to the one process that "+
+				"needs it", found["mode"])
+		}
+	})
+
+	t.Run("a module that does not claim the seat is refused", func(t *testing.T) {
+		m := theBus()
+		m.Claims = nil
+		if _, err := on(t, m, Rendering{BusUsers: "accounts {}"}); err == nil {
+			t.Fatal("a module that claims nothing was handed every user's password hash")
+		}
+	})
+
+	t.Run("the holder with nothing composed is refused", func(t *testing.T) {
+		if _, err := on(t, theBus(), Rendering{}); err == nil {
+			t.Fatal("the bus was given an empty user list, so it would refuse every connection in " +
+				"the mesh and look like a machine problem")
+		}
+	})
+
+	t.Run("a module that did not ask gets nothing", func(t *testing.T) {
+		m := theBus()
+		m.BusUsers = ""
+		resources, err := on(t, m, Rendering{BusUsers: "accounts {}"})
+		if err != nil {
+			t.Fatal(err)
+		}
+		for _, r := range resources {
+			if r["id"] == "nats."+BusUsersID() {
+				t.Fatal("a module that asked for no user list was given one")
+			}
+		}
+	})
+}
@@ -0,0 +1,205 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// aMediaServer is the shape one port number per key cannot express: two endpoints of different kinds.
+// A web surface a proxy serves under a subdomain, and a protocol port clients dial directly because
+// the client expects that number.
+func aMediaServer() Manifest {
+	return Manifest{
+		Module: "media",
+		Listens: []Listening{
+			{Name: "web", Port: 80, From: FromMesh, Why: "the app, behind the proxy"},
+			{Name: "stream", Port: 32400, From: FromEverywhere, Fixed: true,
+				Why: "the client dials this number; the protocol chose it"},
+		},
+		Contributes: map[string]map[string]any{
+			"route": {"label": "media", RouteEndpoint: "web"},
+		},
+		// Both endpoints are published by its container, which is what lets a machine port be given
+		// for either: the mesh moves a port the module publishes, never one it merely listens on.
+		Resources: []map[string]any{
+			{"id": "server", "type": "container", "name": "media",
+				"ports": []any{"80", "32400"}},
+		},
+	}
+}
+
+// **A route names the endpoint it serves.** A route and a listen both carried a port and nothing said
+// they were the same thing; now one of them says so.
+func TestARouteNamesTheEndpointItServes(t *testing.T) {
+	m := aMediaServer()
+	if port, ok := EndpointPort(m, "web"); !ok || port != 80 {
+		t.Fatalf("the web endpoint resolves to %d (%v), want 80", port, ok)
+	}
+	if port, ok := EndpointPort(m, "stream"); !ok || port != 32400 {
+		t.Fatalf("the stream endpoint resolves to %d (%v), want 32400", port, ok)
+	}
+	if _, ok := EndpointPort(m, "absent"); ok {
+		t.Fatal("an endpoint the module does not declare resolved to a port")
+	}
+}
+
+// And the routed set is read through the name, so the endpoint the proxy serves is known without a
+// reader joining two numbers.
+func TestTheRoutedEndpointIsFoundByName(t *testing.T) {
+	routed := RoutedPorts(aMediaServer())
+	if !routed[80] {
+		t.Fatalf("the routed endpoint was not found by name: %v", routed)
+	}
+	// And the directly-dialled one is not routed, which is what lets its reach govern its port.
+	if routed[32400] {
+		t.Fatalf("the endpoint clients dial directly reads as routed: %v", routed)
+	}
+}
+
+// **Two endpoints of different shapes, configured as themselves.** The web endpoint's reach asks for
+// names and leaves its port to the proxy; the stream endpoint's reach governs its port, because
+// clients dial it and there is no name.
+func TestTwoEndpointsOfDifferentShapesAreConfiguredSeparately(t *testing.T) {
+	m := aMediaServer()
+	settings := SettingsBy{"media": {{From: "node anchor", Values: map[string]any{
+		ReachSetting: map[string]any{"80": ReachBoth, "32400": ReachPublic},
+	}}}}
+
+	r := Resolution{Node: "anchor", Modules: []Manifest{m},
+		PublicDomain: "example.test", At: "anchor.internal"}
+	rules, err := r.Rules(Rendering{Settings: settings})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, rule := range rules {
+		switch rule.Port {
+		case 80:
+			if rule.From != FromMesh {
+				t.Fatalf("the routed endpoint's port opened to %q; the proxy is how it is reached",
+					rule.From)
+			}
+		case 32400:
+			if rule.From != FromEverywhere {
+				t.Fatalf("the directly-dialled endpoint's port is %q, want anywhere", rule.From)
+			}
+		}
+	}
+
+	// And the routed one carries both names, asked for by the same statement.
+	given, err := r.contributions(settings, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var public, internal string
+	for _, c := range given["route"] {
+		public, _ = c.Values["name"].(string)
+		internal, _ = c.Values["internal-name"].(string)
+	}
+	if public != "media.example.test" || internal != "media.anchor.internal" {
+		t.Fatalf("names are %q and %q, want both", public, internal)
+	}
+}
+
+// A route naming an endpoint the module does not declare reaches nothing, and is refused where it is
+// written rather than resolving to no port and serving nothing.
+func TestARouteNamingAnEndpointTheModuleLacksIsRefused(t *testing.T) {
+	m := aMediaServer()
+	m.Contributes["route"][RouteEndpoint] = "absent"
+	got := strings.Join(RouteProblems(m), "\n")
+	if !strings.Contains(got, "does not declare") {
+		t.Fatalf("a route naming an absent endpoint was accepted:\n%s", got)
+	}
+}
+
+// **Two endpoints called the same would make an assignment configure whichever was read last.** The
+// point of a name is that it identifies one thing.
+func TestTwoEndpointsWithOneNameAreRefused(t *testing.T) {
+	m := Manifest{Module: "twice", Listens: []Listening{
+		{Name: "web", Port: 80, From: FromMesh},
+		{Name: "web", Port: 8080, From: FromMesh},
+	}}
+	got := strings.Join(endpointNameProblems(m), "\n")
+	if !strings.Contains(got, "could mean either") {
+		t.Fatalf("two endpoints with one name were accepted:\n%s", got)
+	}
+}
+
+// A name that is not a name is refused where it is written: it ends up in something a person types.
+func TestAnEndpointNameIsHeldToItsShape(t *testing.T) {
+	for _, wrong := range []string{"Web", "web port", "3000", "-web", "web_surface"} {
+		m := Manifest{Module: "odd", Listens: []Listening{{Name: wrong, Port: 80, From: FromMesh}}}
+		if got := strings.Join(endpointNameProblems(m), "\n"); !strings.Contains(got, "a name is lowercase") {
+			t.Fatalf("%q was accepted as an endpoint name:\n%s", wrong, got)
+		}
+	}
+}
+
+// **Every endpoint in the catalogue is unnamed today, and must stay valid.** The word ships one
+// release before anything uses it.
+func TestAnUnnamedEndpointIsStillValid(t *testing.T) {
+	m := Manifest{Module: "ordinary", Listens: []Listening{{Port: 443, From: FromEverywhere}}}
+	if got := endpointNameProblems(m); len(got) != 0 {
+		t.Fatalf("an unnamed endpoint was refused: %v", got)
+	}
+	if got := RouteProblems(m); len(got) != 0 {
+		t.Fatalf("a module with no route was refused: %v", got)
+	}
+}
+
+// **A route that names an endpoint still carries that endpoint's port.**
+//
+// Everything downstream reads the port: the provider is told where to reach the consumer, and the
+// redirection that turns a declared port into the number the machine published is keyed on it. A route
+// naming only its endpoint left the proxy with no port, and a proxy with no port has nothing to dial.
+//
+// Caught after the catalogue had already been changed to name endpoints, and before the mesh picked
+// those manifests up — which is the only reason nothing broke.
+func TestARouteNamingAnEndpointStillCarriesItsPort(t *testing.T) {
+	m := aMediaServer()
+	r := Resolution{Node: "anchor", Modules: []Manifest{m},
+		PublicDomain: "example.test", At: "anchor.internal"}
+	given, err := r.contributions(nil, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var saw bool
+	for _, c := range given["route"] {
+		saw = true
+		port, ok := asPort(c.Values["port"])
+		if !ok {
+			t.Fatalf("the route carries no port, so the proxy has nothing to dial: %v", c.Values)
+		}
+		if port != 80 {
+			t.Fatalf("the route carries port %d, want the web endpoint's 80", port)
+		}
+	}
+	if !saw {
+		t.Fatal("the module contributed no route")
+	}
+}
+
+// And the declared port, not the machine one: the redirection to where the machine published it
+// happens later and is keyed on the declared number, so filling the machine port in here would be
+// redirected twice or not at all.
+func TestTheEndpointsDeclaredPortIsFilledInNotTheMachineOne(t *testing.T) {
+	m := aMediaServer()
+	values := map[string]any{RouteEndpoint: "web", "label": "media"}
+	portOfEndpoint(values, endpointPorts(m))
+	if got, _ := asPort(values["port"]); got != 80 {
+		t.Fatalf("filled in port %d, want the declared 80", got)
+	}
+	// Then the ordinary redirection puts it where the machine published it.
+	moved := atMachinePort(values, m.Module, map[string]map[int]int{"media": {80: 20009}})
+	if got, _ := asPort(moved["port"]); got != 20009 {
+		t.Fatalf("after redirection the port is %d, want the machine's 20009", got)
+	}
+}
+
+// A route that repeats a port keeps it, because that is the older shape and still read.
+func TestARouteThatRepeatsItsPortKeepsIt(t *testing.T) {
+	values := map[string]any{RouteEndpoint: "web", "port": 8080}
+	portOfEndpoint(values, map[string]int{"web": 80})
+	if got, _ := asPort(values["port"]); got != 8080 {
+		t.Fatalf("the port it stated was overwritten with %d", got)
+	}
+}
@@ -0,0 +1,140 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+func configured(block map[string]any) SettingsBy {
+	return SettingsBy{"media": {{From: "node anchor",
+		Values: map[string]any{EndpointsSetting: block}}}}
+}
+
+// **One block per endpoint, saying all three things.** The machine port, the subdomain and the reach
+// were `ports`, the route's label and `reach`, each keyed by a port number, so configuring a module
+// with two endpoints of different shapes meant knowing which number was which.
+func TestAnEndpointsBlockSaysPortLabelAndReach(t *testing.T) {
+	m := aMediaServer()
+	// stream's reach NARROWS what the manifest says — the manifest has it from anywhere, the
+	// assignment says internal. Chosen deliberately: a reach that agrees with the manifest proves
+	// nothing about whether the block was read at all.
+	settings := configured(map[string]any{
+		"web":    map[string]any{"port": 20009, "label": "cinema", "reach": ReachBoth},
+		"stream": map[string]any{"reach": ReachInternal},
+	})
+
+	// The machine port, where the mapping is read.
+	given, err := GivenPorts(m, settings["media"])
+	if err != nil {
+		t.Fatal(err)
+	}
+	if given[80] != 20009 {
+		t.Fatalf("the web endpoint is on machine port %d, want 20009: %v", given[80], given)
+	}
+
+	// The reach, where the filter reads it.
+	r := Resolution{Node: "anchor", Modules: []Manifest{m},
+		PublicDomain: "example.test", At: "anchor.internal"}
+	rules, err := r.Rules(Rendering{Settings: settings})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, rule := range rules {
+		if rule.Port == 32400 && rule.From != FromMesh {
+			t.Fatalf("the directly-dialled endpoint is %q; the assignment narrowed it to the private "+
+				"network and the manifest's 'anywhere' should not win", rule.From)
+		}
+		if rule.Port == 80 && rule.From != FromMesh {
+			t.Fatalf("the routed endpoint's port opened to %q; the proxy is how it is reached", rule.From)
+		}
+	}
+
+	// And the subdomain, where the name is composed — the assignment's, not the module's.
+	nodes, err := r.contributions(settings, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, c := range nodes["route"] {
+		if got, _ := c.Values["name"].(string); got != "cinema.example.test" {
+			t.Fatalf("the public name is %q, want the label the assignment gave", got)
+		}
+		if got, _ := c.Values["internal-name"].(string); got != "cinema.anchor.internal" {
+			t.Fatalf("the internal name is %q, want the label the assignment gave", got)
+		}
+	}
+}
+
+// A block that says only a reach leaves the port to the mesh and the label to the module, which is the
+// ordinary case and must not require writing the other two.
+func TestABlockMaySayOnlyAReach(t *testing.T) {
+	m := aMediaServer()
+	settings := configured(map[string]any{"web": map[string]any{"reach": ReachInternal}})
+	r := Resolution{Node: "anchor", Modules: []Manifest{m},
+		PublicDomain: "example.test", At: "anchor.internal"}
+	nodes, err := r.contributions(settings, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, c := range nodes["route"] {
+		if got, _ := c.Values["name"].(string); got != "" {
+			t.Fatalf("an internal endpoint composed the public name %q", got)
+		}
+		// The module's own label, untouched.
+		if got, _ := c.Values["internal-name"].(string); got != "media.anchor.internal" {
+			t.Fatalf("the internal name is %q, want the module's own label", got)
+		}
+	}
+}
+
+// An endpoint the module does not declare reaches nothing, and the refusal says what it does declare.
+func TestConfiguringAnEndpointTheModuleLacksIsRefused(t *testing.T) {
+	_, err := Endpoints(aMediaServer(), configured(map[string]any{
+		"admin": map[string]any{"reach": ReachInternal}})["media"])
+	if err == nil || !strings.Contains(err.Error(), "does not declare") {
+		t.Fatalf("configuring an absent endpoint was accepted: %v", err)
+	}
+	if err != nil && !strings.Contains(err.Error(), "stream") {
+		t.Fatalf("the refusal does not name what the module declares: %v", err)
+	}
+}
+
+func TestAReachInABlockIsHeldToTheFourValues(t *testing.T) {
+	_, err := Endpoints(aMediaServer(), configured(map[string]any{
+		"web": map[string]any{"reach": "mesh"}})["media"])
+	if err == nil || !strings.Contains(err.Error(), "a reach is") {
+		t.Fatalf("a filter word was accepted as a reach: %v", err)
+	}
+}
+
+// **Two places giving one endpoint a machine port is the confusion this key exists to end.**
+func TestAnEndpointGivenAPortTwiceIsRefused(t *testing.T) {
+	m := aMediaServer()
+	_, err := GivenPorts(m, []Layer{{From: "node anchor", Values: map[string]any{
+		EndpointsSetting: map[string]any{"web": map[string]any{"port": 20009}},
+		PortsSetting:     map[string]any{"80": 30000},
+	}}})
+	if err == nil || !strings.Contains(err.Error(), "published once") {
+		t.Fatalf("an endpoint given two machine ports was accepted: %v", err)
+	}
+}
+
+// And the same for its reach, said once here and once through the older key.
+func TestAnEndpointWhoseReachIsAlsoExposedIsRefused(t *testing.T) {
+	_, err := Endpoints(aMediaServer(), []Layer{{From: "node anchor", Values: map[string]any{
+		EndpointsSetting: map[string]any{"web": map[string]any{"reach": ReachInternal}},
+		ExposeSetting:    map[string]any{"80": FromEverywhere},
+	}}})
+	if err == nil || !strings.Contains(err.Error(), "same thing in different words") {
+		t.Fatalf("a reach said two ways was accepted: %v", err)
+	}
+}
+
+// A module whose endpoints are unnamed cannot be configured this way, and is told so rather than
+// having a block silently reach nothing — which is every module in the catalogue today.
+func TestAModuleWithNoNamedEndpointsIsToldSo(t *testing.T) {
+	m := Manifest{Module: "media", Listens: []Listening{{Port: 80, From: FromMesh}}}
+	_, err := Endpoints(m, configured(map[string]any{"web": map[string]any{"reach": ReachBoth}})["media"])
+	if err == nil || !strings.Contains(err.Error(), "no endpoints by name") {
+		t.Fatalf("a module with no named endpoints accepted a block: %v", err)
+	}
+}
@@ -0,0 +1,161 @@
+package catalogue
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// What a module may call an event, and what a consumer may ask for.
+//
+// A module names an event **locally**: `order.placed`, not a subject and not a routing key
+// (design 29 §1). A consumer names the emitter and the event: `billing.order.placed`. The mesh
+// derives the subject from those, so reorganising the subject space leaves every manifest correct.
+//
+// **Nothing checked this until every manifest in the catalogue was wrong the same way**
+// (novox/hq 04-ISSUES/127). All thirty-seven kept the old bus's routing key —
+// `module.<module>.<verb>` — which the derivation read as "a module called `module`", so every
+// cross-module subscription in the mesh pointed at a namespace nobody publishes to. Nothing failed:
+// the services started and none of them reacted. The documentation on these fields taught the old
+// form too, which is why the drift was uniform rather than scattered.
+
+// eventName is one name in a local event: lower-case, and no wildcard.
+var eventName = regexp.MustCompile(`^[a-z0-9][a-z0-9-]*$`)
+
+// The wildcards a consumer may use, spelled the mesh's way and derived to whatever the transport
+// spells them as.
+//
+// **A manifest holds no transport token**, which is the whole point of naming locally: the bus the
+// mesh runs on today spells these `*` and `#`, and the one being built spells them `*` and `>`. A
+// manifest that said either would be a manifest that stopped being true when the wire changed.
+const (
+	// OneName stands for exactly one name.
+	OneName = "*"
+	// TheRest stands for one or more names, and may only come last.
+	TheRest = "**"
+)
+
+// EventProblems is what is wrong with a manifest's events.
+//
+// Refused at registration, because the alternative is a module that installs, starts, connects and
+// reacts to nothing — and every log line says it is fine.
+func EventProblems(m Manifest) []string {
+	var problems []string
+
+	for _, e := range m.Emits {
+		if was, stale := staleEventForm(e, m.Module); stale {
+			problems = append(problems, fmt.Sprintf(
+				"%s emits %q, which is the old bus's routing key. An event is named locally now, so "+
+					"write %q — the mesh derives the subject (novox/hq design 29 §1)",
+				m.Module, was, strings.TrimPrefix(was, "module."+m.Module+".")))
+			continue
+		}
+		if strings.HasPrefix(e, "module.") {
+			problems = append(problems, fmt.Sprintf(
+				"%s emits %q: `module.` is reserved, because it is how the old bus spelled a "+
+					"routing key and an event named that way derives into a namespace nobody owns",
+				m.Module, e))
+			continue
+		}
+		if err := localName(e); err != nil {
+			problems = append(problems, fmt.Sprintf("%s emits %q: %v", m.Module, e, err))
+			continue
+		}
+		// **Its own name, never another's.** The bus enforces that a namespace belongs to the module
+		// it is named for, so an event named for somebody else cannot be published at all. If the
+		// event is about a role rather than about this module, it belongs on the seat: a name that
+		// is stable across whoever fills it (04-ISSUES/127).
+		if first, _, split := strings.Cut(e, "."); split && isAModuleNameOtherThan(first, m.Module) {
+			problems = append(problems, fmt.Sprintf(
+				"%s emits %q, which reads as another module's event. A module publishes under its "+
+					"own name only. If this is about a role rather than about %s, declare it on that "+
+					"seat, where the name survives the holder changing",
+				m.Module, e, m.Module))
+		}
+	}
+
+	for _, c := range m.Consumes {
+		if strings.HasPrefix(c, "module.") {
+			problems = append(problems, fmt.Sprintf(
+				"%s consumes %q, which is the old bus's pattern. A consumed event names its emitter "+
+					"and the event: write %q", m.Module, c, strings.TrimPrefix(c, "module.")))
+			continue
+		}
+		if c == "#" {
+			problems = append(problems, fmt.Sprintf(
+				"%s consumes %q, which is the old bus's wildcard for everything. Write %q",
+				m.Module, c, TheRest))
+			continue
+		}
+		if err := consumePattern(c); err != nil {
+			problems = append(problems, fmt.Sprintf("%s consumes %q: %v", m.Module, c, err))
+		}
+	}
+	return problems
+}
+
+// staleEventForm says an emitted name is this module's own old routing key, and what it was.
+func staleEventForm(event, module string) (string, bool) {
+	return event, module != "" && strings.HasPrefix(event, "module."+module+".")
+}
+
+// isAModuleNameOtherThan says a first token names some module of this mesh that is not this one.
+//
+// Only the mesh's own seats and the catalogue could answer this properly, and neither is reachable
+// from a parser given one manifest. So this catches the case that actually happened — a name that
+// is a *provision* the mesh defines, which is where "another module's event" comes from in practice
+// — and the whole-catalogue check catches the rest.
+func isAModuleNameOtherThan(first, module string) bool {
+	if first == module || first == "" {
+		return false
+	}
+	if _, isASeat := SeatNamed(first); isASeat {
+		return true
+	}
+	if _, isASeat := SeatDelivering(first); isASeat {
+		return true
+	}
+	return false
+}
+
+// localName checks one event name: dot-separated names, no wildcards, nothing else.
+func localName(event string) error {
+	if event == "" {
+		return fmt.Errorf("an event needs a name")
+	}
+	for _, part := range strings.Split(event, ".") {
+		if part == OneName || part == TheRest {
+			return fmt.Errorf("an emitted event names one event, so it carries no wildcard")
+		}
+		if !eventName.MatchString(part) {
+			return fmt.Errorf("%q is not a usable name: lower-case letters, digits and dashes", part)
+		}
+	}
+	return nil
+}
+
+// consumePattern checks a consumed pattern: the emitter, then the event, with wildcards.
+func consumePattern(pattern string) error {
+	if pattern == "" {
+		return fmt.Errorf("a consumed event needs an emitter and an event")
+	}
+	parts := strings.Split(pattern, ".")
+	for i, part := range parts {
+		switch {
+		case part == TheRest:
+			if i != len(parts)-1 {
+				return fmt.Errorf("%q stands for the rest of a name, so nothing may follow it", TheRest)
+			}
+		case part == OneName:
+		case !eventName.MatchString(part):
+			return fmt.Errorf("%q is not a usable name: lower-case letters, digits and dashes", part)
+		}
+	}
+	// `**` alone is every event from every module, which the audit logger wants and says plainly.
+	if len(parts) == 1 && parts[0] != TheRest {
+		return fmt.Errorf(
+			"%q names an emitter and no event. Write <emitter>.<event>, or %q for every event",
+			pattern, TheRest)
+	}
+	return nil
+}
@@ -1,184 +0,0 @@
-package catalogue
-
-import (
-	"fmt"
-	"sort"
-	"strings"
-)
-
-// What only the mesh knows, written where a module asks for it.
-//
-// **The graph is the control plane's; using it is the module's.** The mesh knows which machines
-// exist, what they are called, and where they are. Turning that into a name that resolves is
-// somebody's software, and which software is a choice the mesh should not be making.
-//
-// This replaced three modules — names, a resolver's data, and the private network's own
-// configuration — that existed only because computed output needed somewhere to live. They ran no
-// software and could not be swapped for anything, which is the test of whether something is a
-// module at all (novox/hq ADR 0040).
-
-const (
-	// FactNodeNames is every machine's name and address, as a hosts file.
-	//
-	// Exact names only: `homer` and `homer.internal` resolve to homer. Anything *under* a machine
-	// is a wildcard, which a hosts file cannot express — that is FactNodeZones.
-	FactNodeNames = "node-names"
-
-	// FactNodeZones is every machine as a wildcard: `*.homer.internal` is homer.
-	//
-	// Written in the form a resolver reads. A machine's own name and everything under it are one
-	// fact — if homer is at an address, so is anything homer serves.
-	FactNodeZones = "node-zones"
-)
-
-// facts is every fact the mesh computes, and what writes it.
-//
-// **A closed list.** A module asking for a fact the mesh does not have is asking for a file nobody
-// will write, and finding that out on a machine — as a daemon that starts, reads nothing, and
-// answers no queries — is worse than being told where the manifest is.
-// A fact is written from the names it is about. `every` is every name the mesh serves — machines
-// and the names it was told to route; `machines` is only the machines. A fact takes the set it is
-// true of, and the two must not be confused (novox/hq 04-ISSUES/111).
-var facts = map[string]func(r Resolution, every, machines map[string]string, suffix string) string{
-	FactNodeNames: func(r Resolution, every, _ map[string]string, suffix string) string {
-		return nodeNames(r, every, suffix)
-	},
-	FactNodeZones: func(r Resolution, _, machines map[string]string, suffix string) string {
-		return nodeZones(r, machines, suffix)
-	},
-}
-
-// FactsInto renders the facts a module asked for, as files it will be given.
-//
-// The module owns everything after the file exists: loading it, restarting on it, what a resolver
-// does with it. This only puts it there.
-func FactsInto(m Manifest, r Resolution, addresses, machines map[string]string, suffix string) ([]map[string]any, error) {
-	if len(m.Facts) == 0 {
-		return nil, nil
-	}
-	names := make([]string, 0, len(m.Facts))
-	for name := range m.Facts {
-		names = append(names, name)
-	}
-	sort.Strings(names)
-
-	out := make([]map[string]any, 0, len(names))
-	for _, name := range names {
-		write, known := facts[name]
-		if !known {
-			return nil, fmt.Errorf(
-				"%s asks the mesh for %q, which it does not compute. It has %s",
-				m.Module, name, spokenFacts())
-		}
-		path := m.Facts[name]
-		if !strings.HasPrefix(path, "/") {
-			return nil, fmt.Errorf(
-				"%s asks for %q at %q, which is not an absolute path", m.Module, name, path)
-		}
-		out = append(out, map[string]any{
-			"id": "fact-" + name, "type": "file", "path": path, "mode": "0644",
-			"content": write(r, addresses, machines, suffix),
-		})
-	}
-	return out, nil
-}
-
-// spokenFacts lists them, so a refusal says what would have worked.
-func spokenFacts() string {
-	names := make([]string, 0, len(facts))
-	for name := range facts {
-		names = append(names, name)
-	}
-	sort.Strings(names)
-	return strings.Join(names, ", ")
-}
-
-// nodeNames is every machine's name and address, as a hosts file.
-//
-// **A machine with no address is left out.** The mesh has a record for it — somebody added it —
-// and does not yet know where it is, which is the ordinary state between adding a machine and it
-// joining. Writing the name anyway would give a name that resolves to nothing, and a connection to
-// that hangs; leaving it out fails at once and says the name is unknown.
-func nodeNames(r Resolution, addresses map[string]string, suffix string) string {
-	var b strings.Builder
-	b.WriteString("# Generated by the mesh. Do not edit — this file is replaced whenever a machine\n")
-	b.WriteString("# joins or leaves, and an edit would survive until then and vanish.\n\n")
-	// The floor every Linux expects, and which removing would break things that have nothing to do
-	// with the mesh.
-	b.WriteString("127.0.0.1\tlocalhost\n")
-	b.WriteString("::1\t\tlocalhost ip6-localhost ip6-loopback\n")
-	if r.Node != "" {
-		fmt.Fprintf(&b, "127.0.1.1\t%s\n", r.Node)
-	}
-	b.WriteString("\n")
-	for _, name := range sortedNames(addresses) {
-		at := addresses[name]
-		internal, bare := meshName(name, suffix)
-		// Its mesh name resolves to its address on the private network rather than to loopback,
-		// so a service binding the name it was given stays reachable from everywhere else.
-		fmt.Fprintf(&b, "%s\t%s\t%s", at, internal, bare)
-		if bare == r.Node {
-			b.WriteString("\t# this machine")
-		}
-		b.WriteString("\n")
-	}
-	return b.String()
-}
-
-// nodeZones is every machine as a wildcard, in the form a resolver reads.
-//
-// `*.homer.internal` is homer, which is the whole rule: if homer is at an address, so is anything
-// homer serves. A module wanting this runs the resolver; the mesh only says what is true.
-//
-// **And the suffix itself, as a local domain.** A resolver that forwards what it cannot answer
-// would otherwise send a mesh name it does not know — a machine that left, a typo — to a public
-// resolver, which is a leak of the mesh's names for no answer. `local=` keeps everything under the
-// suffix here: answered from the lines below or refused. Written in this file rather than in the
-// resolver's own configuration because the suffix is the mesh's choice (the operator may have
-// picked another) and this file is the one place the mesh writes what it chose.
-func nodeZones(_ Resolution, addresses map[string]string, suffix string) string {
-	var b strings.Builder
-	b.WriteString("# Generated by the mesh. Do not edit — this file is replaced whenever a machine\n")
-	b.WriteString("# joins or leaves, and an edit would survive until then and vanish.\n\n")
-	fmt.Fprintf(&b, "local=/%s/\n", strings.TrimPrefix(suffixOr(suffix), "."))
-	for _, name := range sortedNames(addresses) {
-		internal, _ := meshName(name, suffix)
-		fmt.Fprintf(&b, "address=/%s/%s\n", internal, addresses[name])
-	}
-	return b.String()
-}
-
-// meshName is a machine's internal name and its bare one, from either. The control plane keys
-// the names it hands a resolution by the internal name (`homer.internal`), the same map a
-// container gets as its hosts; a caller that keys by the bare name gets the same answer. The
-// suffix is the one the control plane composed those names with, handed down rather than written
-// here a second time — the alternative was `homer.internal.internal` on every machine.
-func meshName(name, suffix string) (internal, bare string) {
-	dotted := "." + strings.TrimPrefix(suffixOr(suffix), ".")
-	if strings.HasSuffix(name, dotted) {
-		return name, strings.TrimSuffix(name, dotted)
-	}
-	return name + dotted, name
-}
-
-// suffixOr is the suffix given, or the one the mesh composes names with when none was handed down.
-// The one place the default is written in this file, so a fact and a name cannot disagree about it.
-func suffixOr(suffix string) string {
-	if suffix == "" {
-		return "internal"
-	}
-	return suffix
-}
-
-func sortedNames(addresses map[string]string) []string {
-	out := make([]string, 0, len(addresses))
-	for name, at := range addresses {
-		// See nodeNames: a machine the mesh cannot place is left out rather than named at nothing.
-		if at == "" {
-			continue
-		}
-		out = append(out, name)
-	}
-	sort.Strings(out)
-	return out
-}
@@ -1,188 +0,0 @@
-package catalogue
-
-import (
-	"strings"
-	"testing"
-)
-
-// Keyed by the internal name, as the control plane hands them (issue 079).
-var threeMachines = map[string]string{"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2", "bart.internal": ""}
-
-// **`*.homer.internal` is homer. That is the whole rule.** And the suffix itself is local: a
-// resolver that forwards what it cannot answer must not send a mesh name it does not know — a
-// machine that left, a typo — to a public resolver (hal dnsmasq-app conversion, novox/hq
-// 08-connectivity).
-func TestEveryMachineIsAWildcardUnderItsOwnName(t *testing.T) {
-	out := nodeZones(Resolution{Node: "homer"}, threeMachines, "")
-	for _, want := range []string{
-		"local=/internal/",
-		"address=/homer.internal/10.42.0.1",
-		"address=/marge.internal/10.42.0.2",
-	} {
-		if !strings.Contains(out, want) {
-			t.Fatalf("missing %q:\n%s", want, out)
-		}
-	}
-}
-
-// A machine the mesh has a record for and cannot place is left out of both.
-//
-// **Not an oversight — the alternative is worse.** A name written with no address resolves to
-// nothing, and a connection to that hangs. Leaving it out fails at once and says the name is
-// unknown, which is a thing somebody can act on.
-func TestAMachineWithNoAddressIsNotNamed(t *testing.T) {
-	for _, out := range []string{
-		nodeNames(Resolution{Node: "homer"}, threeMachines, ""),
-		nodeZones(Resolution{Node: "homer"}, threeMachines, ""),
-	} {
-		if strings.Contains(out, "bart") {
-			t.Fatalf("a machine with no address was named, so its name resolves to nothing:\n%s", out)
-		}
-	}
-}
-
-// A machine's own mesh name points at its address on the private network, not at loopback — or a
-// service binding the name it was given is unreachable from everywhere else.
-func TestAMachinesOwnNameIsItsMeshAddress(t *testing.T) {
-	out := nodeNames(Resolution{Node: "homer"}, threeMachines, "")
-	var line string
-	for _, l := range strings.Split(out, "\n") {
-		if strings.Contains(l, "homer.internal") {
-			line = l
-		}
-	}
-	if !strings.HasPrefix(line, "10.42.0.1") {
-		t.Fatalf("a machine's own mesh name is not its mesh address: %q", line)
-	}
-	// And the loopback floor is still there, or things with nothing to do with the mesh break.
-	if !strings.Contains(out, "127.0.0.1\tlocalhost") {
-		t.Fatalf("the loopback floor was removed:\n%s", out)
-	}
-}
-
-// A module says where it wants a fact, and is given a file.
-func TestAModuleIsGivenTheFactsItAskedFor(t *testing.T) {
-	m := Manifest{Module: "dnsmasq", Facts: map[string]string{FactNodeZones: "/etc/mesh/zones.conf"}}
-	given, err := FactsInto(m, Resolution{Node: "homer"}, threeMachines, threeMachines, "")
-	if err != nil {
-		t.Fatal(err)
-	}
-	if len(given) != 1 {
-		t.Fatalf("expected one file, got %d", len(given))
-	}
-	if given[0]["path"] != "/etc/mesh/zones.conf" || given[0]["type"] != "file" {
-		t.Fatalf("not written where it was asked for: %v", given[0])
-	}
-	if !strings.Contains(given[0]["content"].(string), "homer.internal") {
-		t.Fatalf("the file does not hold the fact: %v", given[0]["content"])
-	}
-}
-
-// **Asking for a fact the mesh does not have is refused here, not on a machine.** A daemon that
-// starts, reads a file nobody wrote, and answers no queries is a much worse way to find out.
-func TestAskingForAFactTheMeshDoesNotHaveIsRefused(t *testing.T) {
-	m := Manifest{Module: "dnsmasq", Facts: map[string]string{"the-weather": "/etc/weather"}}
-	_, err := FactsInto(m, Resolution{}, nil, nil, "")
-	if err == nil {
-		t.Fatal("a module asked for something nobody computes and was given nothing, silently")
-	}
-	for _, known := range []string{FactNodeNames, FactNodeZones} {
-		if !strings.Contains(err.Error(), known) {
-			t.Fatalf("the refusal does not say what would have worked: %v", err)
-		}
-	}
-}
-
-// And a relative path is refused, or a module decides where the mesh writes on a machine.
-func TestAFactMustBeAskedForAtAnAbsolutePath(t *testing.T) {
-	m := Manifest{Module: "dnsmasq", Facts: map[string]string{FactNodeNames: "etc/hosts"}}
-	if _, err := FactsInto(m, Resolution{}, nil, nil, ""); err == nil {
-		t.Fatal("a relative path was accepted")
-	}
-}
-
-// **The names the control plane hands a resolution are already internal names** — `homer.internal`,
-// the same map every container gets as its hosts. Appending the suffix again wrote
-// `homer.internal.internal` into every hosts file and every resolver's zones, and the large mesh
-// bed's name test was the first to read it back. Either key gives the same files.
-func TestNamesKeyedByInternalNameAreNotSuffixedTwice(t *testing.T) {
-	internal := map[string]string{"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2"}
-	bare := map[string]string{"homer": "10.42.0.1", "marge": "10.42.0.2"}
-	if a, b := nodeZones(Resolution{Node: "homer"}, internal, ""), nodeZones(Resolution{Node: "homer"}, bare, ""); a != b {
-		t.Fatalf("the zones differ by how the names were keyed:\n%s\n---\n%s", a, b)
-	}
-	if a, b := nodeNames(Resolution{Node: "homer"}, internal, ""), nodeNames(Resolution{Node: "homer"}, bare, ""); a != b {
-		t.Fatalf("the hosts differ by how the names were keyed:\n%s\n---\n%s", a, b)
-	}
-	zones := nodeZones(Resolution{Node: "homer"}, internal, "")
-	if strings.Contains(zones, "internal.internal") || !strings.Contains(zones, "address=/homer.internal/10.42.0.1") {
-		t.Fatalf("the zones carry a doubled suffix or miss the name:\n%s", zones)
-	}
-	hosts := nodeNames(Resolution{Node: "homer"}, internal, "")
-	if !strings.Contains(hosts, "10.42.0.1\thomer.internal\thomer\t# this machine") {
-		t.Fatalf("the hosts line for the machine itself is not name, bare name and the mark:\n%s", hosts)
-	}
-}
-
-// The suffix the control plane composed the names with is the one the facts write — an operator
-// who chose another does not get `.internal` appended to it.
-func TestTheFactsWriteTheSuffixTheNamesWereComposedWith(t *testing.T) {
-	names := map[string]string{"homer.lan": "10.42.0.1"}
-	zones := nodeZones(Resolution{Node: "homer"}, names, "lan")
-	if !strings.Contains(zones, "address=/homer.lan/10.42.0.1") || strings.Contains(zones, "internal") {
-		t.Fatalf("the zones do not carry the operator's suffix as given:\n%s", zones)
-	}
-	if !strings.Contains(zones, "local=/lan/") {
-		t.Fatalf("the local domain is not the operator's suffix, so its names would leak upstream:\n%s", zones)
-	}
-	hosts := nodeNames(Resolution{Node: "homer"}, names, "lan")
-	if !strings.Contains(hosts, "10.42.0.1\thomer.lan\thomer\t# this machine") {
-		t.Fatalf("the hosts line does not carry the operator's suffix as given:\n%s", hosts)
-	}
-}
-
-// novox/hq 04-ISSUES/111: the map the control plane hands a resolution holds every name the mesh
-// serves — the machines, and the names it was told to route to whichever machine serves them. A
-// container's hosts wants all of it. A resolver's zones want only the machines: told the mesh's
-// suffix is its own, it answers authoritatively for everything under it and forwards nothing, so a
-// routed name written there with the suffix appended is a name nobody will ever ask for, standing
-// beside the machines and looking as real.
-func TestTheResolverIsToldTheMachinesAndNotTheNamesTheMeshMerelyServes(t *testing.T) {
-	machines := map[string]string{"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2"}
-	every := map[string]string{
-		"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2",
-		"drive.example.test": "10.42.0.1", "git.example.test": "10.42.0.2",
-	}
-	m := Manifest{Module: "resolver", Facts: map[string]string{
-		FactNodeZones: "/etc/zones.conf", FactNodeNames: "/etc/hosts",
-	}}
-	given, err := FactsInto(m, Resolution{Node: "homer"}, every, machines, "")
-	if err != nil {
-		t.Fatal(err)
-	}
-	by := map[string]string{}
-	for _, f := range given {
-		by[f["path"].(string)] = f["content"].(string)
-	}
-
-	zones := by["/etc/zones.conf"]
-	for _, machine := range []string{"address=/homer.internal/10.42.0.1", "address=/marge.internal/10.42.0.2"} {
-		if !strings.Contains(zones, machine) {
-			t.Fatalf("the resolver was not told %q:\n%s", machine, zones)
-		}
-	}
-	for _, served := range []string{"drive.example.test", "git.example.test"} {
-		if strings.Contains(zones, served) {
-			t.Fatalf("the resolver was told %q, a name the mesh serves rather than a machine:\n%s", served, zones)
-		}
-	}
-
-	// And the hosts file is the other way about: every name, so a container reaching a routed name
-	// finds the machine serving it.
-	hosts := by["/etc/hosts"]
-	for _, name := range []string{"homer.internal", "drive.example.test", "git.example.test"} {
-		if !strings.Contains(hosts, name) {
-			t.Fatalf("a container would not resolve %q from its hosts:\n%s", name, hosts)
-		}
-	}
-}
@@ -230,7 +230,23 @@ const SSHPort = 22
 // It is a floor for the same reason ssh is. A machine nobody can reach is a machine nobody can
 // repair; a machine the mesh cannot reach is a machine the mesh cannot manage. Neither is a thing
 // any module asks for, and neither may be derived away.
-func AsNftables(rules []Rule, mesh []string, outward bool, foundation []int) string {
+func AsNftables(rules []Rule, mesh []string, outward bool, foundation []int,
+	outwardLinks []string, tunnel string) string {
+	// The links that are not this machine's own: the ones facing outside, and the mesh's tunnel.
+	// Traffic arriving on any of them is admitted only by a rule below; traffic arriving anywhere
+	// else is this machine's own guest and is not something the mesh has a position on.
+	//
+	// The tunnel is named here deliberately. Treating it as "not outside" would make a port nothing
+	// declares reachable from every machine in the mesh, which is the derivation abandoned.
+	quoted := make([]string, 0, len(outwardLinks)+1)
+	for _, link := range outwardLinks {
+		quoted = append(quoted, fmt.Sprintf("%q", link))
+	}
+	if tunnel != "" {
+		quoted = append(quoted, fmt.Sprintf("%q", tunnel))
+	}
+	inward := strings.Join(quoted, ", ")
+
 	var b strings.Builder
 	b.WriteString("# Computed by the mesh from what is assigned to this node.\n")
 	b.WriteString("# Edits are lost on the next declaration; change a module's listens instead.\n\n")
@@ -249,9 +265,45 @@ func AsNftables(rules []Rule, mesh []string, outward bool, foundation []int) str
 	b.WriteString("\t\tct state established,related accept\n")
 	b.WriteString("\t\tct state invalid drop\n")
 	b.WriteString("\t\tiif lo accept\n")
+	// **Anything on this machine may call anything on this machine.**
+	//
+	// Local is not a boundary this mesh draws. A service running here is callable by everything else
+	// running here, whatever form either takes — a package with a unit, a binary, a container. Whether
+	// a caller sits in a container was never meant to change the answer, and the only reason it did was
+	// that this chain asked about addresses: a caller on the machine carries the machine's address, a
+	// caller in one of its containers carries a bridge address, and a rule naming the former silently
+	// refused the latter.
+	//
+	// Measured: a module reaching its database on this machine's own name timed out for eleven hours
+	// while the machine itself could reach it, and the mesh called the machine healthy throughout
+	// (novox/hq 04-ISSUES/145).
+	//
+	// Asked by the link it arrives on rather than the address it comes from: anything that did not
+	// arrive from outside this machine, and did not arrive over the private network, is this machine's
+	// own. One rule for every service here, in place of a line per port that only ever covered the
+	// ports somebody remembered to think about.
+	if inward != "" {
+		b.WriteString(fmt.Sprintf("\t\tiifname != { %s } accept\n", inward))
+	}
 	b.WriteString("\t\ticmp type echo-request accept\n")
 	b.WriteString("\t\ticmpv6 type { echo-request, nd-neighbor-solicit, nd-neighbor-advert, nd-router-advert } accept\n")

+	// **What this machine's own guests must be able to ask it** (novox/hq ADR 0140). A guest gets
+	// its address and its names from this machine, over the link it is on, and those two questions
+	// arrive at the input chain like any other. Denied, the guest never gets an address and never
+	// resolves a name — which is not "a closed port" but a network that does not work at all, and it
+	// is this machine's own guest asking.
+	//
+	// Asked for by the link it arrives on rather than by the address it comes from, for the reason
+	// the forward chain below no longer names an address: a range describes one machine and goes
+	// stale in silence. Anything arriving from outside, or over the tunnel, is not a guest of this
+	// machine and asks through a port somebody declared, like everything else.
+	if len(inward) > 0 {
+		b.WriteString("\t\t# this machine's own guests asking it for an address and for names\n")
+		b.WriteString(fmt.Sprintf("\t\tiifname != { %s } udp dport { 53, 67 } accept\n", inward))
+		b.WriteString(fmt.Sprintf("\t\tiifname != { %s } tcp dport 53 accept\n", inward))
+	}
+
 	// **ssh, always, and not because a module asked.**
 	//
 	// Every other line in this chain is derived from what is assigned here, which is the whole
@@ -361,19 +413,36 @@ func AsNftables(rules []Rule, mesh []string, outward bool, foundation []int) str
 	// about the ports most worth protecting. Rehearsed on three machines: loading these rules
 	// refused a port on the host and left a published container port reachable (novox/hq issue 047).
 	//
-	// The way through is the one the system being replaced already used: deny by default here, and
-	// then explicitly allow the runtime's own networks, so containers keep working while everything
-	// else has to be asked for.
+	// **What it constrains is traffic arriving from OUTSIDE this machine, and nothing else**
+	// (novox/hq ADR 0140).
+	//
+	// It used to deny everything here and then allow the machine's own containers back by naming
+	// the address ranges they sit on — two ranges fixed in this file and the rest recorded per
+	// machine. Every way of keeping that list correct failed. A constant describes one machine. A
+	// recorded range goes stale in silence and cannot tell a network the mesh made from one a
+	// predecessor left behind. Generating it from the modules would have put half this rule set on
+	// the machine.
+	//
+	// The list should not exist, because the mesh has no position on a container reaching outward:
+	// that is not a port opened to anybody. So traffic that did not arrive from outside is accepted
+	// in one line, and what did arrive from outside is allowed only where a rule below admits it.
+	//
+	// The tunnel is not "not outside". Accepting everything off it would make a port nothing
+	// declares reachable from any machine in the mesh, which is the derivation abandoned — so it is
+	// named here beside the outward links, and traffic arriving on it meets the rules below like
+	// anything else.
 	b.WriteString("\tchain forward {\n")
 	b.WriteString("\t\ttype filter hook forward priority filter; policy drop;\n")
 	b.WriteString("\t\tct state established,related accept\n")
 	b.WriteString("\t\tct state invalid drop\n")
 	b.WriteString("\n")
-	// What the container runtime created. Without these, denying by default stops every container
-	// on the machine — which is exactly the failure the absent chain was avoiding, avoided properly.
-	for _, network := range runtimeNetworks {
-		b.WriteString(fmt.Sprintf("\t\t# %s\n", network.why))
-		b.WriteString(fmt.Sprintf("\t\tip saddr %s accept\n", network.cidr))
+	// Only when there is a link to name. An empty set is a line nftables refuses, and a rule set
+	// that does not load is a machine filtering nothing while its unit reports success — so the
+	// chain denies rather than renders nonsense. Composing a declaration for a machine that has
+	// named none is refused upstream, so this is a floor and not a path anything travels.
+	if inward != "" {
+		b.WriteString("\t\t# this machine's own guests reaching outward: not a port opened to anybody\n")
+		b.WriteString(fmt.Sprintf("\t\tiifname != { %s } accept\n", inward))
 	}

 	if len(rules) > 0 {
@@ -430,18 +499,6 @@ func AsNftables(rules []Rule, mesh []string, outward bool, foundation []int) str
 	return b.String()
 }

-// runtimeNetworks are the container runtime's own networks, which must keep working when the
-// forward chain denies by default.
-//
-// Taken from what the system being replaced allows, which has been carrying this machine's traffic
-// for months: the runtime's bridge range and the range its compose files are given. A machine whose
-// runtime is configured with something else needs this to say so — which is a thing the mesh cannot
-// derive and a reason this list is named here rather than computed.
-var runtimeNetworks = []struct{ cidr, why string }{
-	{"172.16.0.0/12", "the container runtime's bridge networks"},
-	{"192.168.128.0/17", "the networks its compose files are given"},
-}
-
 // byFamily splits addresses into the two nftables understands separately.
 //
 // `ip saddr` and `ip6 saddr` are different matches, and one set holding both families is a syntax
@@ -499,6 +556,21 @@ const MeshWideLayer = "the mesh"
 // two mappings share a number, it is an entry one of them writes over the other's, and the reader
 // that finds the survivor disagrees with the reader that recomputes it.
 func GivenPorts(m Manifest, layers []Layer) (map[int]int, error) {
+	// An endpoint's own block may put it on a machine port, which is the same thing `ports` says about
+	// the number rather than about the endpoint (novox/hq ADR 0138). Collected first and then let the
+	// older key be read, which refuses a port said twice.
+	byName, err := Endpoints(m, layers)
+	if err != nil {
+		return nil, err
+	}
+	named := map[int]int{}
+	for name, ep := range byName {
+		if ep.Port == 0 {
+			continue
+		}
+		named[endpointPorts(m)[name]] = ep.Port
+	}
+
 	// Every name a setting may use, and the mapping it names.
 	names := map[int][]publishing{}
 	for _, p := range publishedPorts(m) {
@@ -597,6 +669,17 @@ func GivenPorts(m Manifest, layers []Layer) (map[int]int, error) {
 			out[key], by[key] = at, port
 		}
 	}
+	// And what the endpoints' own blocks put them on. Refused rather than merged where both keys name
+	// one endpoint: two places giving a port is the confusion this key exists to end.
+	for wanted, at := range named {
+		if was, twice := out[wanted]; twice && was != at {
+			return nil, fmt.Errorf(
+				"%s puts its port %d on %d through %s and on %d through %s — one endpoint, two "+
+					"machine ports, and it is published once. Keep the endpoint's own block",
+				m.Module, wanted, at, EndpointsSetting, was, PortsSetting)
+		}
+		out[wanted] = at
+	}
 	if len(out) == 0 {
 		return nil, nil
 	}
@@ -664,3 +747,332 @@ func sortedPorts(of map[int]int) []int {
 	sort.Ints(out)
 	return out
 }
+
+// ReachSetting is the settings key that says how far one of a module's endpoints reaches, per node
+// (novox/hq ADR 0138):
+//
+//	{"reach": {"3000": "internal"}}
+//
+// **One value, three readers.** Reachability used to be settled three times over: the filter read a
+// listen's source, which `expose` could override; the proxy composed a public name and an internal
+// name for every route it was given, because it could; and the certificate authority followed from
+// which names existed. Each was defensible and the combination was unstated, so "this endpoint must
+// not be public" could not be written and was therefore enforced by nothing — while a public
+// certificate for that very name was obtained anyway.
+//
+// It keys on the port the module declares, the same key `ports` and `expose` use. A route names that
+// port too, which is what lets one statement reach the names as well as the filter: of the 36 route
+// entries in the catalogue, 35 name a port that the same module declares a listen on, and the one
+// that does not is a path-level refusal — a rule about a name rather than an endpoint.
+const ReachSetting = "reach"
+
+// How far an endpoint reaches. Four values, because they have to cover everything `expose` could say
+// as well as the two names.
+const (
+	// ReachMachine is this machine only: not the private network, not the world, and no name.
+	ReachMachine = "machine"
+	// ReachInternal is the private network, under the internal name and not the public one.
+	ReachInternal = "internal"
+	// ReachPublic is the world, under the public name and not the internal one.
+	ReachPublic = "public"
+	// ReachBoth is the world, under both names — each certified by its own authority.
+	//
+	// The filter cannot distinguish this from ReachPublic, and should not try: the mesh's addresses
+	// are a subset of anywhere. What differs is the names, which is the whole reason reach is not
+	// simply the filter's vocabulary with nicer words.
+	ReachBoth = "both"
+)
+
+// reaches is every value, in the order a refusal lists them.
+var reaches = []string{ReachMachine, ReachInternal, ReachPublic, ReachBoth}
+
+// RoutedPorts are the ports a module serves through a proxy, taken from its route contributions.
+//
+// **A routed endpoint's port is how the proxy reaches it, and nothing else.** That is ADR 0045's
+// decision and it is older than reach: a public service listens `from: mesh`, only the proxy reaches
+// it, and it is exposed by name. So `public` on a routed endpoint asks for a public *name*; opening
+// that port to the world as well would undo the arrangement the proxy exists for.
+//
+// Measured before this was written, not reasoned: a module's routed name answered from the internet
+// over TLS while its machine-side port was refused from the same place. The port is not the path.
+func RoutedPorts(m Manifest) map[int]bool {
+	out := map[int]bool{}
+	note := func(values map[string]any) {
+		// **The endpoint it serves, by name where it says one.** A route repeating a port number is
+		// the older shape and still read: 35 of the catalogue's 36 route entries name a port their
+		// module declares a listen on (novox/hq ADR 0138).
+		if name, ok := values[RouteEndpoint].(string); ok {
+			if port, found := EndpointPort(m, name); found {
+				out[port] = true
+				return
+			}
+		}
+		if port, ok := asPort(values["port"]); ok {
+			out[port] = true
+		}
+	}
+	if values, ok := m.Contributes["route"]; ok {
+		note(values)
+	}
+	for _, values := range m.ContributesMany["route"] {
+		note(values)
+	}
+	return out
+}
+
+// FilterSource is the source a reach means to the packet filter.
+//
+// `public` and `both` are the same here. A reach that opened a port to the mesh and not to the world
+// would be `internal`; there is no reach that opens it to the world and *not* to the mesh, because a
+// filter cannot express "everyone except these" and nobody has asked for it.
+func FilterSource(reach string) (string, bool) {
+	switch reach {
+	case ReachMachine:
+		return FromMachine, true
+	case ReachInternal:
+		return FromMesh, true
+	case ReachPublic, ReachBoth:
+		return FromEverywhere, true
+	default:
+		return "", false
+	}
+}
+
+// WantsPublicName is whether a reach asks for the route's public name to be composed.
+func WantsPublicName(reach string) bool { return reach == ReachPublic || reach == ReachBoth }
+
+// WantsInternalName is whether a reach asks for the route's internal name to be composed.
+func WantsInternalName(reach string) bool { return reach == ReachInternal || reach == ReachBoth }
+
+// Reaches reads a module's per-node reach settings: declared port → how far it reaches.
+//
+// It refuses a reach for a port the module does not listen on, or a value that is not one of the
+// four — the "reads as a restriction and is none" fault this whole mechanism exists to prevent
+// (novox/hq ADR 0043/0045). It also refuses a port that `expose` names as well: the two say the same
+// thing in different words, and a module whose reach and exposure disagree would have the filter
+// following one and the names following the other, which is the very confusion ADR 0138 removes.
+//
+// A module with no `reach` setting yields nothing, and everything behaves exactly as before: the
+// filter follows the manifest's `from`, and both names are composed. That is what keeps every machine
+// already running unchanged until an assignment says otherwise.
+func Reaches(m Manifest, layers []Layer) (map[int]string, error) {
+	listened := make(map[int]bool, len(m.Listens))
+	for _, l := range m.Listens {
+		listened[l.Port] = true
+	}
+
+	exposed, err := Exposure(m, layers)
+	if err != nil {
+		return nil, err
+	}
+
+	out := map[int]string{}
+	// What an endpoint's own block says, which is the same statement in the shape that names the
+	// endpoint rather than its port (novox/hq ADR 0138). Read first so the older key, which says less,
+	// cannot quietly win over the newer one that says more.
+	blocks, err := Endpoints(m, layers)
+	if err != nil {
+		return nil, err
+	}
+	declared := endpointPorts(m)
+	for name, ep := range blocks {
+		if ep.Reach == "" {
+			continue
+		}
+		out[declared[name]] = ep.Reach
+	}
+	for _, layer := range layers {
+		raw, ok := layer.Values[ReachSetting]
+		if !ok {
+			continue
+		}
+		entries, ok := raw.(map[string]any)
+		if !ok {
+			return nil, fmt.Errorf("%s: %s is a { port: reach } map, and %q set it to something else",
+				m.Module, ReachSetting, layer.From)
+		}
+		for portText, value := range entries {
+			port, err := strconv.Atoi(portText)
+			if err != nil {
+				return nil, fmt.Errorf("%s says how far %q reaches, which is not a port", m.Module, portText)
+			}
+			if !listened[port] {
+				return nil, fmt.Errorf(
+					"%s says how far port %d reaches, which it does not listen on — the setting "+
+						"reaches nothing", m.Module, port)
+			}
+			reach, ok := value.(string)
+			if !ok || !slices.Contains(reaches, reach) {
+				return nil, fmt.Errorf("%s says port %d reaches %v; a reach is %s",
+					m.Module, port, value, strings.Join(reaches, ", "))
+			}
+			if _, both := exposed[port]; both {
+				return nil, fmt.Errorf(
+					"%s sets both %s and %s for port %d. They say the same thing in different "+
+						"words, and the filter would follow one while its names followed the other "+
+						"— which is what %s exists to stop. Keep %s",
+					m.Module, ReachSetting, ExposeSetting, port, ReachSetting, ReachSetting)
+			}
+			out[port] = reach
+		}
+	}
+	if len(out) == 0 {
+		return nil, nil
+	}
+	return out, nil
+}
+
+// RouteEndpoint is the key a route contribution names the endpoint it serves with, instead of
+// repeating that endpoint's port (novox/hq ADR 0138).
+//
+// **A route and a listen both carried a port, and nothing said they were the same thing.** They
+// always were — a route serves one of the module's own endpoints — but a reader had to join two
+// numbers, and an assignment configuring "the web endpoint" had to know which number that was. A
+// route that names the endpoint says what it means, and the mesh looks the port up.
+const RouteEndpoint = "endpoint"
+
+// RouteProblems holds a module's route contributions to naming an endpoint it actually has.
+//
+// A route naming an endpoint the module does not declare reaches nothing, and is refused where it is
+// written rather than resolving to no port and serving nothing — the fault this repository names most
+// often, a declaration that reads as though it did something.
+func RouteProblems(m Manifest) []string {
+	var problems []string
+	check := func(where string, values map[string]any) {
+		name, ok := values[RouteEndpoint].(string)
+		if !ok || strings.TrimSpace(name) == "" {
+			return
+		}
+		if _, found := EndpointPort(m, name); !found {
+			problems = append(problems, fmt.Sprintf(
+				"%s routes %s to the endpoint %q, which it does not declare", m.Module, where, name))
+		}
+	}
+	if values, ok := m.Contributes["route"]; ok {
+		check("a name", values)
+	}
+	for local, values := range m.ContributesMany["route"] {
+		check(local, values)
+	}
+	return problems
+}
+
+// EndpointsSetting is the settings key that configures a module's endpoints by name, per node
+// (novox/hq ADR 0138):
+//
+//	{"endpoints": {"web":    {"port": 20009, "label": "media", "reach": "both"},
+//	               "stream": {"reach": "public"}}}
+//
+// **One block per endpoint, instead of three keys joined by a number.** Which machine port it lands
+// on, the subdomain a proxy serves it under, and how far it reaches are the three things an operator
+// says when a module is assigned, and they were said in `ports`, in the route's label and in `reach`,
+// each keyed by the port. A module with two endpoints of different shapes — a web surface behind the
+// proxy and a protocol port clients dial directly — could only be configured by a reader who knew
+// which number was which.
+//
+// Every field is optional. A block that says only a reach leaves the port to the mesh and the label to
+// the module, which is the ordinary case.
+const EndpointsSetting = "endpoints"
+
+// Endpoint is what an assignment says about one of a module's endpoints.
+type Endpoint struct {
+	// Port is the machine-side port it is published on. Zero means the mesh assigns one, which it
+	// does anyway — a fixed port is the module's claim and is honoured without being said here.
+	Port int
+	// Label is the subdomain a proxy serves it under, overriding the one the module contributes.
+	Label string
+	// Reach is how far it reaches: machine, internal, public or both.
+	Reach string
+}
+
+// Endpoints reads a module's per-node endpoint configuration, by endpoint name.
+//
+// It refuses a name the module does not declare — the setting would reach nothing — and a reach that
+// is not one of the four. It also refuses an endpoint whose port or reach is said twice, once here and
+// once through the older key: two places saying the same thing is what this key exists to end, and
+// letting both stand would mean the mesh followed whichever it read last.
+func Endpoints(m Manifest, layers []Layer) (map[string]Endpoint, error) {
+	declared := endpointPorts(m)
+	exposed, err := Exposure(m, layers)
+	if err != nil {
+		return nil, err
+	}
+
+	out := map[string]Endpoint{}
+	for _, layer := range layers {
+		raw, ok := layer.Values[EndpointsSetting]
+		if !ok {
+			continue
+		}
+		blocks, ok := raw.(map[string]any)
+		if !ok {
+			return nil, fmt.Errorf("%s: %s is a { endpoint: { … } } map, and %q set it to something else",
+				m.Module, EndpointsSetting, layer.From)
+		}
+		for name, body := range blocks {
+			port, known := declared[name]
+			if !known {
+				return nil, fmt.Errorf(
+					"%s configures the endpoint %q, which it does not declare — the setting reaches "+
+						"nothing. It declares %s", m.Module, name, spokenEndpoints(m))
+			}
+			values, ok := body.(map[string]any)
+			if !ok {
+				return nil, fmt.Errorf("%s: the endpoint %q is configured with something that is not a "+
+					"block of settings", m.Module, name)
+			}
+			ep := out[name]
+			if reach, said := values["reach"]; said {
+				text, ok := reach.(string)
+				if !ok || !slices.Contains(reaches, text) {
+					return nil, fmt.Errorf("%s says the endpoint %q reaches %v; a reach is %s",
+						m.Module, name, reach, strings.Join(reaches, ", "))
+				}
+				if _, also := exposed[port]; also {
+					return nil, fmt.Errorf(
+						"%s says how far %q reaches and also exposes port %d. They say the same thing "+
+							"in different words; keep the endpoint's own block",
+						m.Module, name, port)
+				}
+				ep.Reach = text
+			}
+			if at, said := values["port"]; said {
+				machine, ok := asPort(at)
+				if !ok {
+					return nil, fmt.Errorf("%s puts the endpoint %q on %v, which is not a port",
+						m.Module, name, at)
+				}
+				ep.Port = machine
+			}
+			if label, said := values["label"]; said {
+				text, ok := label.(string)
+				if !ok || strings.TrimSpace(text) == "" {
+					return nil, fmt.Errorf("%s gives the endpoint %q a label that is not a name: %v",
+						m.Module, name, label)
+				}
+				ep.Label = strings.TrimSpace(text)
+			}
+			out[name] = ep
+		}
+	}
+	if len(out) == 0 {
+		return nil, nil
+	}
+	return out, nil
+}
+
+// spokenEndpoints is what a module's endpoints are called, as a refusal lists them — so a reader who
+// named one wrongly is one edit from right, and a module that has named none is told so.
+func spokenEndpoints(m Manifest) string {
+	names := make([]string, 0, len(m.Listens))
+	for _, l := range m.Listens {
+		if name := strings.TrimSpace(l.Name); name != "" {
+			names = append(names, name)
+		}
+	}
+	if len(names) == 0 {
+		return "no endpoints by name"
+	}
+	sort.Strings(names)
+	return strings.Join(names, ", ")
+}
@@ -19,7 +19,7 @@ func TestTheBrokersPortIsOpenedThoughNoModuleDeclaresIt(t *testing.T) {
 	// A machine on the private network, with one ordinary module rule, and nothing that mentions
 	// the broker — which is every machine.
 	rules := []Rule{{Port: 8080, From: FromMesh, Because: []string{"some-module"}}}
-	out := AsNftables(rules, []string{"10.42.0.1"}, false, []int{brokerPort})
+	out := AsNftables(rules, []string{"10.42.0.1"}, false, []int{brokerPort}, nil, "mesh0")

 	if !strings.Contains(out, "tcp dport 5671 accept") {
 		t.Fatalf("the broker's port is not opened, so no machine could enrol:\n%s", out)
@@ -48,7 +48,7 @@ func TestTheBrokersPortIsOpenedThoughNoModuleDeclaresIt(t *testing.T) {
 // And a mesh that was never told about a broker still gets a ruleset, rather than an empty one or
 // a panic. A control plane in that state cannot issue tokens either, which is where it surfaces.
 func TestNoBrokerMeansNoFoundationRuleRatherThanNoRuleset(t *testing.T) {
-	out := AsNftables(nil, []string{"10.42.0.1"}, false, nil)
+	out := AsNftables(nil, []string{"10.42.0.1"}, false, nil, nil, "mesh0")
 	if !strings.Contains(out, "table inet mesh") {
 		t.Fatalf("no ruleset at all:\n%s", out)
 	}
@@ -79,7 +79,7 @@ func TestTwoModulesWantingOnePortAreBothNamed(t *testing.T) {
 		t.Fatalf("a module that wanted this port open is not named: %+v", rules[0])
 	}
 	// The consequence, which is the reason this matters: removing web must not read as closing 443.
-	nft := AsNftables(rules, nil, false, nil)
+	nft := AsNftables(rules, nil, false, nil, nil, "mesh0")
 	if !strings.Contains(nft, "web") || !strings.Contains(nft, "board") {
 		t.Fatalf("the rendered rule set does not name both sources:\n%s", nft)
 	}
@@ -107,7 +107,7 @@ func TestAPortOpenToEveryoneIsNotAlsoRestrictedToTheMesh(t *testing.T) {
 func TestWhatNoModuleDeclaredIsClosed(t *testing.T) {
 	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
 		{Module: "web", Listens: []Listening{{Port: 443, From: FromEverywhere}}},
-	}}, nil), []string{"198.51.100.2"}, false, nil)
+	}}, nil), []string{"198.51.100.2"}, false, nil, nil, "mesh0")
 	// Naming the chain, not just the policy: the forward chain drops too, and an assertion on
 	// "policy drop" alone passes while the input chain accepts everything. It did, once, here.
 	if !strings.Contains(nft, "type filter hook input priority filter; policy drop;") {
@@ -134,7 +134,7 @@ func TestWhatNoModuleDeclaredIsClosed(t *testing.T) {
 // `flush ruleset` would do the first and not the second: it empties every table on the machine,
 // including the ones the container runtime writes for its bridges.
 func TestReloadingReplacesOnlyTheMeshsOwnRules(t *testing.T) {
-	nft := AsNftables(nil, nil, false, nil)
+	nft := AsNftables(nil, nil, false, nil, nil, "mesh0")
 	if strings.Contains(nft, "flush ruleset") {
 		t.Fatalf("loading the rule set empties every table on the machine:\n%s", nft)
 	}
@@ -160,22 +160,122 @@ func TestReloadingReplacesOnlyTheMeshsOwnRules(t *testing.T) {
 // So the chain exists and denies by default, and the runtime's own networks are allowed explicitly
 // — which is how the system being replaced has been doing it on these machines for months.
 func TestWhatIsForwardedIsGovernedToo(t *testing.T) {
-	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil)
+	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil, nil, "mesh0")
 	if !strings.Contains(nft, "hook forward priority filter; policy drop") {
 		t.Fatalf("forwarded traffic is not governed, so container ports are open:\n%s", nft)
 	}
 }

-// And containers keep working, which is the whole reason the chain was left out before.
-func TestTheRuntimesOwnNetworksKeepWorking(t *testing.T) {
-	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil)
-	for _, network := range []string{"172.16.0.0/12", "192.168.128.0/17"} {
-		if !strings.Contains(nft, "ip saddr "+network+" accept") {
-			t.Fatalf("%s is not allowed, so denying by default stops every container:\n%s", network, nft)
+// And this machine's own guests keep working, which is the whole reason the chain was left out
+// before — by not being mentioned (novox/hq ADR 0140).
+//
+// It used to be done by naming the address ranges they sit on: two fixed here and the rest recorded
+// per machine. That list broke a workstation's containers at a flip and could not be made correct,
+// because a range describes one machine and cannot tell a network the mesh made from one a
+// predecessor left behind. What replaced it is a single line about the links traffic arrives on.
+func TestThisMachinesOwnGuestsKeepWorkingWithoutBeingNamed(t *testing.T) {
+	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil, []string{"eth0"}, "mesh0")
+	if !strings.Contains(nft, `iifname != { "eth0", "mesh0" } accept`) {
+		t.Fatalf("what did not arrive from outside is not accepted, so this machine's own guests "+
+			"reach nothing:\n%s", nft)
+	}
+}
+
+// No address of a machine's own networks appears anywhere in a rendered filter.
+//
+// This is the assertion that fails against the previous behaviour, and it is why it is written on
+// the text rather than on an outcome: the two ranges were a constant in this file, so nothing but
+// reading the output catches one creeping back in.
+func TestNoNetworkOfTheMachinesOwnIsNamed(t *testing.T) {
+	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil, []string{"eth0"}, "mesh0")
+	for _, gone := range []string{"172.16.0.0/12", "192.168.128.0/17", "saddr 192.168", "saddr 172."} {
+		if strings.Contains(nft, gone) {
+			t.Fatalf("%q is named, and a range describes one machine and goes stale in silence:\n%s",
+				gone, nft)
 		}
 	}
 }

+// **The tunnel is constrained, not treated as inside.**
+//
+// Accepting everything arriving over the private network would make a port nothing declares
+// reachable from every machine in the mesh — the derivation abandoned, and a rule that reads as a
+// restriction while restricting nothing. So the tunnel is named beside the outward links, and
+// traffic arriving on it meets the declared rules like anything else.
+func TestTheTunnelIsConstrainedLikeAnOutwardLink(t *testing.T) {
+	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil, []string{"eth0"}, "mesh0")
+	line := `iifname != { "eth0", "mesh0" } accept`
+	if !strings.Contains(nft, line) {
+		t.Fatalf("the tunnel is not constrained, so an undeclared port is reachable from any "+
+			"machine in the mesh:\n%s", nft)
+	}
+}
+
+// A machine with two links facing outside has both constrained. Asserted on the one line, because a
+// rule covering one and not the other would leave a machine filtering half of what reaches it.
+func TestEveryOutwardLinkIsConstrained(t *testing.T) {
+	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil, []string{"eth0", "wlan0"}, "mesh0")
+	if !strings.Contains(nft, `iifname != { "eth0", "wlan0", "mesh0" } accept`) {
+		t.Fatalf("not every outward link is constrained:\n%s", nft)
+	}
+}
+
+// A guest asks its host for an address and for names, and those two arrive at the input chain. Asked
+// for by the link they arrive on, so a resolver bound anywhere but an outward link keeps answering.
+func TestGuestsMayAskTheirHostForAnAddressAndNames(t *testing.T) {
+	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil, []string{"eth0"}, "mesh0")
+	for _, want := range []string{
+		`iifname != { "eth0", "mesh0" } udp dport { 53, 67 } accept`,
+		`iifname != { "eth0", "mesh0" } tcp dport 53 accept`,
+	} {
+		if !strings.Contains(nft, want) {
+			t.Fatalf("a guest cannot ask its host for an address or a name, which is not a closed "+
+				"port but a network that does not work:\n%s", nft)
+		}
+	}
+}
+
+// With no link named at all the chain denies rather than rendering an empty set, which nftables
+// refuses — and a rule set that does not load is a machine filtering nothing while its unit reports
+// success. Composing a declaration for such a machine is refused upstream; this is the floor.
+func TestNoLinkNamedRendersNoCatchAllRatherThanAnEmptySet(t *testing.T) {
+	nft := AsNftables(nil, []string{"198.51.100.2"}, false, nil, nil, "")
+	if strings.Contains(nft, "{  }") || strings.Contains(nft, "iifname != {}") {
+		t.Fatalf("an empty set is rendered, which nftables refuses:\n%s", nft)
+	}
+	if !strings.Contains(nft, "hook forward priority filter; policy drop") {
+		t.Fatalf("the forward chain does not deny:\n%s", nft)
+	}
+}
+
+// A machine that has not said which links face outside is sent no filter, and the refusal names the
+// module that would have loaded it so the reader knows what is being withheld.
+func TestAMachineThatNamedNoOutwardLinkIsSentNoFilter(t *testing.T) {
+	r := Resolution{Node: "anchor", Modules: []Manifest{
+		{Module: "nftables", Filtering: &Filtering{Into: "/etc/mesh/filter.nft"}},
+		{Module: "web", Listens: []Listening{{Port: 443, From: FromEverywhere}}},
+	}}
+	_, err := r.Declaration(Rendering{Mesh: []string{"198.51.100.2"}, TunnelInterface: "mesh0"})
+	if err == nil {
+		t.Fatal("a machine that named no outward link was sent a filter written around none")
+	}
+	for _, want := range []string{"anchor", "nftables", "face outside"} {
+		if !strings.Contains(err.Error(), want) {
+			t.Fatalf("the refusal does not say %q: %v", want, err)
+		}
+	}
+}
+
+// And a machine that names none but loads no filter is not refused: there is nothing to write.
+func TestAMachineWithNoFilterModuleIsNotRefused(t *testing.T) {
+	r := Resolution{Node: "anchor", Modules: []Manifest{
+		{Module: "web", Listens: []Listening{{Port: 443, From: FromEverywhere}}},
+	}}
+	if _, err := r.Declaration(Rendering{Mesh: []string{"198.51.100.2"}}); err != nil {
+		t.Fatalf("a machine that loads no filter was refused one: %v", err)
+	}
+}
+
 // A published port is matched by what the client asked for, not by where the packet ends up.
 //
 // The runtime rewrites the destination before this chain sees it, so a rule naming the published
@@ -183,7 +283,7 @@ func TestTheRuntimesOwnNetworksKeepWorking(t *testing.T) {
 func TestAPublishedPortIsMatchedByWhatWasAskedFor(t *testing.T) {
 	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
 		{Module: "web", Listens: []Listening{{Port: 8080, From: FromEverywhere}}},
-	}}, nil), []string{"198.51.100.2"}, false, nil)
+	}}, nil), []string{"198.51.100.2"}, false, nil, nil, "mesh0")
 	if !strings.Contains(nft, "ct original proto-dst 8080 accept") {
 		t.Fatalf("the forwarded rule does not match the port a client asked for:\n%s", nft)
 	}
@@ -193,7 +293,7 @@ func TestAPublishedPortIsMatchedByWhatWasAskedFor(t *testing.T) {
 func TestAMeshScopedPortIsMeshScopedWhenForwarded(t *testing.T) {
 	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
 		{Module: "store", Listens: []Listening{{Port: 5432, From: FromMesh}}},
-	}}, nil), []string{"198.51.100.2"}, false, nil)
+	}}, nil), []string{"198.51.100.2"}, false, nil, nil, "mesh0")
 	if !strings.Contains(nft, "ip saddr { 198.51.100.2 } ct original proto-dst 5432 accept") {
 		t.Fatalf("a mesh-only port is reachable from anywhere once forwarded:\n%s", nft)
 	}
@@ -203,7 +303,7 @@ func TestAMeshScopedPortIsMeshScopedWhenForwarded(t *testing.T) {
 func TestFromTheMeshIsTheNodesTheMeshKnows(t *testing.T) {
 	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
 		{Module: "store", Listens: []Listening{{Port: 5432, From: FromMesh}}},
-	}}, nil), []string{"198.51.100.2", "198.51.100.3"}, false, nil)
+	}}, nil), []string{"198.51.100.2", "198.51.100.3"}, false, nil, nil, "mesh0")
 	if !strings.Contains(nft, "ip saddr { 198.51.100.2, 198.51.100.3 } tcp dport 5432 accept") {
 		t.Fatalf("a mesh-scoped port was not restricted to the mesh's addresses:\n%s", nft)
 	}
@@ -213,7 +313,7 @@ func TestFromTheMeshIsTheNodesTheMeshKnows(t *testing.T) {
 func TestAMeshPortOnANodeWithNoMeshIsClosedAndSaysSo(t *testing.T) {
 	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
 		{Module: "store", Listens: []Listening{{Port: 5432, From: FromMesh}}},
-	}}, nil), nil, false, nil)
+	}}, nil), nil, false, nil, nil, "mesh0")
 	if strings.Contains(nft, "dport 5432 accept") {
 		t.Fatalf("a port meant for the mesh was opened to everything:\n%s", nft)
 	}
@@ -226,7 +326,7 @@ func TestAMeshPortOnANodeWithNoMeshIsClosedAndSaysSo(t *testing.T) {
 func TestAMachineScopedPortIsNotOpened(t *testing.T) {
 	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
 		{Module: "cache", Listens: []Listening{{Port: 6379, From: FromMachine}}},
-	}}, nil), []string{"198.51.100.2"}, false, nil)
+	}}, nil), []string{"198.51.100.2"}, false, nil, nil, "mesh0")
 	if strings.Contains(nft, "dport 6379 accept") {
 		t.Fatalf("a port for this machine only was opened to the network:\n%s", nft)
 	}
@@ -238,7 +338,8 @@ func TestTheModuleAskingForTheRuleSetGetsEveryModulesPorts(t *testing.T) {
 		{Module: "firewall", Filtering: &Filtering{Into: "/etc/mesh/filter.nft"}},
 		{Module: "web", Listens: []Listening{{Port: 443, From: FromEverywhere}}},
 	}}
-	out, err := r.Declaration(Rendering{Mesh: []string{"198.51.100.2"}})
+	out, err := r.Declaration(Rendering{Mesh: []string{"198.51.100.2"},
+		OutwardLinks: []string{"eth0"}, TunnelInterface: "mesh0"})
 	if err != nil {
 		t.Fatalf("declaration: %v", err)
 	}
@@ -268,7 +369,7 @@ func TestAskingForTheRuleSetWithNowhereToPutItIsRefused(t *testing.T) {
 func TestAMeshOnBothAddressFamiliesRendersBoth(t *testing.T) {
 	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
 		{Module: "store", Listens: []Listening{{Port: 5432, From: FromMesh}}},
-	}}, nil), []string{"198.51.100.2", "2001:db8::2"}, false, nil)
+	}}, nil), []string{"198.51.100.2", "2001:db8::2"}, false, nil, nil, "mesh0")
 	if !strings.Contains(nft, "ip saddr { 198.51.100.2 } tcp dport 5432 accept") {
 		t.Fatalf("the machines with v4 addresses were dropped:\n%s", nft)
 	}
@@ -296,7 +397,8 @@ func TestWhatTheMeshComputesIsAppliedBeforeWhatTheModuleDeclared(t *testing.T) {
 				"restart-on": []any{"filtering"}},
 		},
 	}}}
-	out, err := r.Declaration(Rendering{Mesh: []string{"198.51.100.2"}})
+	out, err := r.Declaration(Rendering{Mesh: []string{"198.51.100.2"},
+		OutwardLinks: []string{"eth0"}, TunnelInterface: "mesh0"})
 	if err != nil {
 		t.Fatalf("declaration: %v", err)
 	}
@@ -672,7 +774,7 @@ func TestExposureRefusesAPortNotListenedOnAndABadSource(t *testing.T) {
 // loading the rules lives on conntrack until it drops, and then the machine is reached from a
 // rescue console (novox/hq issue 047).
 func TestSSHIsOpenFromTheMeshEvenWhenNothingIsAssigned(t *testing.T) {
-	nft := AsNftables(nil, []string{"198.51.100.2", "198.51.100.3"}, false, nil)
+	nft := AsNftables(nil, []string{"198.51.100.2", "198.51.100.3"}, false, nil, nil, "mesh0")
 	if !strings.Contains(nft, "ip saddr { 198.51.100.2, 198.51.100.3 } tcp dport 22 accept") {
 		t.Fatalf("ssh is not open to the mesh, so a machine can lock everyone out:\n%s", nft)
 	}
@@ -685,7 +787,7 @@ func TestSSHIsOpenFromTheMeshEvenWhenNothingIsAssigned(t *testing.T) {
 // And from outside as well, on a machine that faces outward — because that is the way in when the
 // private network is the thing that broke.
 func TestSSHIsOpenFromOutsideOnAMachineThatFacesIt(t *testing.T) {
-	nft := AsNftables(nil, []string{"198.51.100.2"}, true, nil)
+	nft := AsNftables(nil, []string{"198.51.100.2"}, true, nil, nil, "mesh0")
 	if !strings.Contains(nft, "\t\ttcp dport 22 accept") {
 		t.Fatalf("a machine reachable from outside does not answer ssh there:\n%s", nft)
 	}
@@ -697,8 +799,91 @@ func TestSSHIsOpenFromOutsideOnAMachineThatFacesIt(t *testing.T) {
 // to narrow the rule to, so narrowing it shuts the port entirely — on the first machine anybody
 // adopts, reached over the network, closed by the act of adopting it.
 func TestSSHIsNeverLeftWithoutARule(t *testing.T) {
-	nft := AsNftables(nil, nil, false, nil)
+	nft := AsNftables(nil, nil, false, nil, nil, "mesh0")
 	if !strings.Contains(nft, "tcp dport 22 accept") {
 		t.Fatalf("a machine with no mesh addresses has no ssh rule, so adopting it locks it:\n%s", nft)
 	}
 }
+
+// chainBody is one chain's own lines, so an assertion cannot be satisfied by an identical line in
+// another chain.
+//
+// **Written because that happened.** The rule letting this machine's own callers through appears in the
+// input chain and, in the same words, in the forward chain. A test asserting on the whole rendered file
+// passed with the input chain's copy deleted — it was reading the forward chain's. ADR 0137's own tests
+// say to assert per chain body for exactly this reason, and this file was not doing it.
+func chainBody(t *testing.T, nft, chain string) string {
+	t.Helper()
+	open := "\tchain " + chain + " {"
+	i := strings.Index(nft, open)
+	if i < 0 {
+		t.Fatalf("no chain %q in:\n%s", chain, nft)
+	}
+	rest := nft[i+len(open):]
+	j := strings.Index(rest, "\n\t}")
+	if j < 0 {
+		t.Fatalf("chain %q does not close in:\n%s", chain, nft)
+	}
+	return rest[:j]
+}
+
+// **Anything on this machine may call anything on this machine.**
+//
+// Local is not a boundary this mesh draws, and whether a caller sits in a container was never meant to
+// change the answer. It did, because the chain asked about addresses: a caller on the machine carries
+// the machine's address and a caller in one of its containers carries a bridge address, so a rule
+// naming the machines' own addresses silently refused every container on them.
+//
+// Measured: a module reaching its database on its own machine's name timed out for eleven hours while
+// the machine itself could reach it (novox/hq 04-ISSUES/145).
+func TestAnythingOnThisMachineMayCallAnythingOnIt(t *testing.T) {
+	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
+		{Module: "store", Listens: []Listening{{Port: 5432, From: FromMesh}}},
+		{Module: "private", Listens: []Listening{{Port: 9999, From: FromMachine}}},
+	}}, nil), []string{"10.10.0.1", "10.10.0.2"}, false, nil, []string{"eth0"}, "mesh0")
+
+	// In the INPUT chain, which is where a call to a service on this machine arrives. The forward
+	// chain carries the same line in the same words, so asserting on the whole file proves nothing.
+	input := chainBody(t, nft, "input")
+	if !strings.Contains(input, `iifname != { "eth0", "mesh0" } accept`) {
+		t.Fatalf("a caller on this machine cannot reach a service on it:\n%s", input)
+	}
+	// One rule, for every service here — not a line per port that only covers the ports somebody
+	// remembered to think about.
+	if strings.Contains(input, `iifname != { "eth0", "mesh0" } tcp dport 5432`) {
+		t.Fatalf("the local allowance is still written per port:\n%s", input)
+	}
+	// And the private network still reaches what is exposed to it, which is a different question.
+	if !strings.Contains(input, "ip saddr { 10.10.0.1, 10.10.0.2 } tcp dport 5432 accept") {
+		t.Fatalf("the private network no longer reaches a service exposed to it:\n%s", input)
+	}
+}
+
+// The three reaches, as three lines. This is the whole of what the filter says about who may call what.
+func TestTheThreeReachesAreThreeLines(t *testing.T) {
+	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
+		{Module: "internal-only", Listens: []Listening{{Port: 5432, From: FromMesh}}},
+		{Module: "public", Listens: []Listening{{Port: 443, From: FromEverywhere}}},
+	}}, nil), []string{"10.10.0.1"}, false, nil, []string{"eth0"}, "mesh0")
+
+	input := chainBody(t, nft, "input")
+	for what, want := range map[string]string{
+		"on this machine":          `iifname != { "eth0", "mesh0" } accept`,
+		"over the private network": "ip saddr { 10.10.0.1 } tcp dport 5432 accept",
+		"from anywhere":            "tcp dport 443 accept",
+	} {
+		if !strings.Contains(input, want) {
+			t.Fatalf("a caller %s cannot reach what is exposed to it (%q):\n%s", what, want, input)
+		}
+	}
+}
+
+// A port open to everything needs no such line — it is already open to a guest.
+func TestAPublicPortNeedsNoGuestLine(t *testing.T) {
+	nft := AsNftables(mustFilter(t, Resolution{Modules: []Manifest{
+		{Module: "web", Listens: []Listening{{Port: 443, From: FromEverywhere}}},
+	}}, nil), []string{"10.10.0.1"}, false, nil, []string{"eth0"}, "mesh0")
+	if strings.Count(nft, `iifname != { "eth0", "mesh0" } tcp dport 443`) != 0 {
+		t.Fatalf("a public port was given a guest line it does not need:\n%s", nft)
+	}
+}
@@ -28,8 +28,10 @@ func TestTheStoreAndTheBrokerSayWhatTheMeshGuards(t *testing.T) {
 	if got := catalogueManifest(t, "postgres").Guards; !reflect.DeepEqual(got, []int{5432}) {
 		t.Errorf("postgres guards %v; the store's port must be refused from outside", got)
 	}
-	if got := catalogueManifest(t, "lavinmq").Guards; !reflect.DeepEqual(got, []int{15672}) {
-		t.Errorf("lavinmq guards %v; the management port must be refused from outside", got)
+	// The bus's monitoring port, not its client port: a node reaches the bus, nobody outside
+	// reads its state (novox/hq ADR 0131 — the broker that guarded 15672 has left the catalogue).
+	if got := catalogueManifest(t, "nats").Guards; !reflect.DeepEqual(got, []int{8222}) {
+		t.Errorf("nats guards %v; the monitoring port must be refused from outside", got)
 	}
 }

@@ -0,0 +1,160 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// **A seat's holder on record settles who holds it, and lets the next holder stand beside the
+// current one** (novox/hq ADR 0131, design 28 task 5.3). Until the record existed, two assignments
+// whose modules both claimed a seat were refused outright — which left no way to hand a seat over
+// without a moment where nobody held it, and the control plane finds its own bus through one of
+// these seats. That moment was the outage of 2026-09-27.
+
+func busSeatDelivering(t *testing.T, delivers string) {
+	t.Helper()
+	was := Seats()
+	t.Cleanup(func() { UseSeats(was) })
+	UseSeats([]Seat{{Name: "mesh-broker", Scope: ScopeMesh, Delivers: delivers, Decision: "test"}})
+}
+
+func oldBroker() Manifest {
+	return Manifest{Module: "old-broker", Provides: []Offer{{Name: "mesh-bus", Scope: ScopeMesh}},
+		Claims: []Claim{{Name: "mesh-broker", Scope: ScopeMesh}}}
+}
+
+func newBroker() Manifest {
+	return Manifest{Module: "new-broker", Provides: []Offer{{Name: "mesh-bus", Scope: ScopeMesh}},
+		Claims: []Claim{{Name: "mesh-broker", Scope: ScopeMesh}}}
+}
+
+// Nothing on record: exactly the old rule. One claimant holds; two are refused.
+func TestWithNoHolderOnRecordTheSoleClaimantHoldsAndTwoAreRefused(t *testing.T) {
+	busSeatDelivering(t, "mesh-bus")
+	node := Node{Name: "anchor"}
+
+	held, problems := checkClaims([]Manifest{oldBroker()}, node, nil, nil)
+	if len(problems) != 0 || len(held) != 1 || held[0].Module != "old-broker" {
+		t.Fatalf("a sole claimant did not hold the seat: held=%v problems=%v", held, problems)
+	}
+	_, problems = checkClaims([]Manifest{oldBroker(), newBroker()}, node, nil, nil)
+	if len(problems) != 1 || !strings.Contains(problems[0], "both claim") {
+		t.Fatalf("two claimants with nothing on record were not refused: %v", problems)
+	}
+}
+
+// With a holder on record, the other eligible assignment is silent: not refused, and not holding.
+func TestTheHolderOnRecordHoldsAndTheOtherClaimantStandsBesideIt(t *testing.T) {
+	busSeatDelivering(t, "mesh-bus")
+	node := Node{Name: "anchor"}
+	record := []Held{{Claim: "mesh-broker", Scope: ScopeMesh, Node: "anchor", Module: "new-broker"}}
+
+	held, problems := checkClaims([]Manifest{oldBroker(), newBroker()}, node, nil, record)
+	if len(problems) != 0 {
+		t.Fatalf("the assignment beside the holder was refused: %v", problems)
+	}
+	if len(held) != 1 || held[0].Module != "new-broker" {
+		t.Fatalf("the holder on record is not the one holding: %v", held)
+	}
+}
+
+// The record names a node too: an eligible module on another machine holds nothing, and its
+// machine's set still resolves.
+func TestAHolderOnRecordElsewhereLeavesThisMachinesClaimantSilent(t *testing.T) {
+	busSeatDelivering(t, "mesh-bus")
+	record := []Held{{Claim: "mesh-broker", Scope: ScopeMesh, Node: "anchor", Module: "new-broker"}}
+
+	held, problems := checkClaims([]Manifest{oldBroker()}, Node{Name: "laptop"}, nil, record)
+	if len(problems) != 0 || len(held) != 0 {
+		t.Fatalf("a claimant elsewhere than the recorded holder was not simply silent: held=%v problems=%v",
+			held, problems)
+	}
+}
+
+// A record naming a seat's former name still applies to it after a rename (ADR 0122).
+func TestAHolderRecordedUnderAFormerNameStillHolds(t *testing.T) {
+	busSeatDelivering(t, "mesh-bus")
+	wasAliases := aliases
+	t.Cleanup(func() { UseAliases(wasAliases) })
+	UseAliases(map[string]string{"the-broker": "mesh-broker"})
+	record := []Held{{Claim: "the-broker", Scope: ScopeMesh, Node: "anchor", Module: "new-broker"}}
+
+	held, problems := checkClaims([]Manifest{oldBroker(), newBroker()}, Node{Name: "anchor"}, nil, record)
+	if len(problems) != 0 || len(held) != 1 || held[0].Module != "new-broker" {
+		t.Fatalf("a record under the former name did not settle the seat: held=%v problems=%v", held, problems)
+	}
+}
+
+// CanHold is the one judgement registration and the handover share, against the store's row.
+func TestCanHoldJudgesClaimScopeAndWhatTheSeatDelivers(t *testing.T) {
+	busSeatDelivering(t, "mesh-bus")
+	seat, _ := SeatNamed("mesh-broker")
+
+	if err := CanHold(newBroker(), seat); err != nil {
+		t.Fatalf("a module that claims the seat and provides what it delivers was refused: %v", err)
+	}
+	noClaim := Manifest{Module: "quiet", Provides: []Offer{{Name: "mesh-bus", Scope: ScopeMesh}}}
+	if err := CanHold(noClaim, seat); err == nil || !strings.Contains(err.Error(), "does not claim") {
+		t.Fatalf("a module that never claimed the seat was allowed to hold it: %v", err)
+	}
+	wrongScope := newBroker()
+	wrongScope.Claims[0].Scope = ScopeNode
+	if err := CanHold(wrongScope, seat); err == nil || !strings.Contains(err.Error(), "scope") {
+		t.Fatalf("a claim at the wrong scope was allowed: %v", err)
+	}
+	cannotAnswer := Manifest{Module: "amqp-only", Provides: []Offer{{Name: "amqp", Scope: ScopeMesh}},
+		Claims: []Claim{{Name: "mesh-broker", Scope: ScopeMesh}}}
+	if err := CanHold(cannotAnswer, seat); err == nil || !strings.Contains(err.Error(), `does not provide "mesh-bus"`) {
+		t.Fatalf("a holder that cannot answer for the seat was allowed: %v", err)
+	}
+	// And the judgement follows the store's row, not a compiled copy.
+	busSeatDelivering(t, "amqp")
+	seat, _ = SeatNamed("mesh-broker")
+	if err := CanHold(cannotAnswer, seat); err != nil {
+		t.Fatalf("with the row saying amqp, an amqp provider was refused: %v", err)
+	}
+}
+
+// A machine being moved is handed its membership for the new bus as a sealed file in its own
+// declaration — the machine's, not any module's (design 28, task 5.2).
+func TestAMembershipForTheNewBusIsComposedAsASealedFile(t *testing.T) {
+	r := Resolution{Node: "anchor"}
+	got, err := r.Compose(Rendering{BusMembership: "sealed-blob"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var found map[string]any
+	for _, res := range got.Resources {
+		if res["id"] == BusMembershipID() {
+			found = res
+		}
+	}
+	if found == nil {
+		t.Fatalf("no membership resource in %v", got.Resources)
+	}
+	if found["path"] != BusMembershipPath || found["sealed"] != "sealed-blob" || found["mode"] != "0600" {
+		t.Fatalf("the membership is not a sealed 0600 file where the host reads it: %v", found)
+	}
+	// And a machine not being moved is handed nothing.
+	got, _ = r.Compose(Rendering{})
+	for _, res := range got.Resources {
+		if res["id"] == BusMembershipID() {
+			t.Fatal("a machine with no membership on record was handed one")
+		}
+	}
+}
+
+// The store's seat rows have no protocol columns yet; loading them must not drop the protocol the
+// bus is derived from, or no role's work queue is ever raised (found live, 2026-09-28).
+func TestAStoreRowWithoutAProtocolKeepsTheCompiledOne(t *testing.T) {
+	was := Seats()
+	t.Cleanup(func() { UseSeats(was) })
+	UseSeats([]Seat{{Name: "mesh-build-machine", Scope: ScopeMesh, Decision: "row"}})
+	got, ok := SeatNamed("mesh-build-machine")
+	if !ok || len(got.Accepts) == 0 {
+		t.Fatalf("the build machine's seat lost what it accepts when loaded from the store: %+v", got)
+	}
+	if got.Decision != "row" {
+		t.Fatalf("the store's own columns were not kept: %+v", got)
+	}
+}
@@ -0,0 +1,106 @@
+package catalogue_test
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/overlay"
+)
+
+// novox/hq issue 128, held where the host will see it: the shipped networking module's names,
+// through the whole composition, and not only through FactsInto.
+//
+// Composition prefixes a fact's id with the module that asked for it and passes everything else
+// through; a step that dropped `into` on the way would send the region as a whole file, and the
+// host would write the machine's hosts file over again with every unit test above still green.
+
+// onTheNetwork stands in for the overlay's generator: the node is part of the private network,
+// and what the generator writes is not what is under test here.
+type onTheNetwork struct{}
+
+func (onTheNetwork) Resources(string) ([]map[string]any, bool, error) {
+	return []map[string]any{{"id": "overlay-config", "type": "file",
+		"path": "/etc/wireguard/mesh0.conf", "mode": "0600", "content": "[Interface]\n"}}, true, nil
+}
+
+func TestTheHostsRegionArrivesAsTheHostWillReadIt(t *testing.T) {
+	shelf := provided(t)
+	// A resolver restarting on the names another module put on the machine, and one resource it
+	// only runs at start — neither of which composition has any business changing.
+	resolver, err := catalogue.ParseManifest([]byte(`{
+		"module": "resolver", "version": "1", "requires": ["mesh-addressing"],
+		"resources": [
+			{"id": "seed", "type": "file", "path": "/etc/resolver/seed", "mode": "0644",
+			 "content": "seed\n", "at": "start"},
+			{"id": "daemon", "type": "service", "unit": "resolver.service", "state": "running",
+			 "restart-on": ["seed", "mesh-wireguard.fact-node-names"]}
+		]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	shelf[resolver.Module] = resolver
+
+	got, err := catalogue.Resolve(shelf, []string{overlay.Domain, "resolver"},
+		catalogue.Node{Name: "homer", At: "homer.internal"}, catalogue.World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	names := map[string]string{"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2"}
+	out, err := got.Declaration(catalogue.Rendering{
+		Names: names, Machines: names, Suffix: "internal",
+		Generators: map[string]catalogue.Generator{overlay.Name: onTheNetwork{}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	ids := map[string]map[string]any{}
+	for _, r := range out {
+		ids[r["id"].(string)] = r
+	}
+
+	hosts := ids[overlay.Name+".fact-node-names"]
+	if hosts == nil {
+		t.Fatalf("no names reached the machine; the declaration has %v", keys(ids))
+	}
+	if hosts["path"] != "/etc/hosts" || hosts["into"] != "block" {
+		t.Fatalf("the hosts file is not written into as a region: %v", hosts)
+	}
+	content := hosts["content"].(string)
+	if !strings.Contains(content, "10.42.0.1\thomer.internal\thomer\t# this machine\n") {
+		t.Errorf("the region does not name the machine:\n%s", content)
+	}
+	for _, floor := range []string{"Generated by the mesh", "localhost", "127.0.1.1"} {
+		if strings.Contains(content, floor) {
+			t.Errorf("the region carries %q, which is the machine's:\n%s", floor, content)
+		}
+	}
+
+	// The resolver's reference to it still names a resource the host will be sent.
+	daemon := ids["resolver.daemon"]
+	if daemon == nil {
+		t.Fatalf("the resolver's service was not composed: %v", keys(ids))
+	}
+	for _, named := range daemon["restart-on"].([]any) {
+		if ids[named.(string)] == nil {
+			t.Errorf("the resolver restarts on %v, which is nothing the host is sent", named)
+		}
+	}
+	if !reflect.DeepEqual(daemon["restart-on"], []any{"resolver.seed", overlay.Name + ".fact-node-names"}) {
+		t.Errorf("restart-on is %v", daemon["restart-on"])
+	}
+
+	// And a resource's own `at` passes through as the manifest wrote it.
+	if seed := ids["resolver.seed"]; seed == nil || seed["at"] != "start" {
+		t.Errorf("a resource's at did not survive composition: %v", seed)
+	}
+}
+
+func keys(m map[string]map[string]any) []string {
+	out := make([]string, 0, len(m))
+	for k := range m {
+		out = append(out, k)
+	}
+	return out
+}
@@ -0,0 +1,62 @@
+package catalogue
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// A node's fail2ban jails, composed from the modules it runs (novox/hq to-be 31).
+//
+// **The same shape as the firewall.** Every module's `listens` become the node's rule set; every
+// module's `jails` become the node's fail2ban config. A module that runs an authenticating service
+// declares what a break-in on it looks like and how to ban it, naming no node and no path (ADR
+// 0112); the intrusion-prevention holder — the one module with `jailing` — gathers them and writes
+// them where it owns. A node not running a module has none of its jails.
+
+// jailsInto composes every jail declared by the modules on a node into the files the holder writes:
+// one jail file (all stanzas, so the fail2ban service restarts on a single resource) and one filter
+// file per jail (its failregex, which fail2ban references by the jail's name).
+//
+// Owned by the holder, because the directory is: two modules writing into one fail2ban is the
+// collision the holder model exists to prevent. Empty when nothing declares a jail — then the file
+// is written empty rather than absent, so removing the last jail is an ordinary change the service
+// restarts on rather than a file that vanishes.
+func jailsInto(modules []Manifest, j *Jailing) []map[string]any {
+	type declared struct {
+		module string
+		jail   Jail
+	}
+	var jails []declared
+	for _, m := range modules {
+		for _, jail := range m.Jails {
+			jails = append(jails, declared{m.Module, jail})
+		}
+	}
+	// A stable order the host applies as given (ADR 0005), and so the same set composes byte for
+	// byte every time rather than differing by map iteration.
+	sort.Slice(jails, func(a, b int) bool { return jails[a].jail.Name < jails[b].jail.Name })
+
+	var composed strings.Builder
+	composed.WriteString("# The mesh's jails, composed from the modules this node runs. Do not edit —\n")
+	composed.WriteString("# replaced whenever the node's modules change (novox/hq to-be 31).\n")
+
+	out := make([]map[string]any, 0, len(jails)+1)
+	for _, d := range jails {
+		fmt.Fprintf(&composed, "\n# from %s\n[%s]\nenabled = true\nfilter = %s\n%s\n",
+			d.module, d.jail.Name, d.jail.Name, strings.TrimRight(d.jail.Jail, "\n"))
+		// The filter is a file of its own, named as the jail's filter= references it.
+		out = append(out, map[string]any{
+			"id":   "filter-" + d.jail.Name,
+			"type": "file", "path": strings.TrimRight(j.FilterInto, "/") + "/" + d.jail.Name + ".conf",
+			"mode": "0644",
+			"content": "# Generated by the mesh (from module " + d.module + "). Do not edit.\n" +
+				"[Definition]\nfailregex = " + d.jail.Failregex + "\n",
+		})
+	}
+	// The one jail file, first, with the fixed id the fail2ban service names in its restart-on.
+	return append([]map[string]any{{
+		"id": ComposedJailsID(), "type": "file", "path": j.Into, "mode": "0644",
+		"content": composed.String(),
+	}}, out...)
+}
@@ -0,0 +1,46 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// A node's fail2ban jails are composed from the modules it runs (novox/hq to-be 31): the holder
+// (jailing) gathers every module's declared jail into one jail file and a filter file per jail.
+func TestJailsAreComposedFromTheNodesModules(t *testing.T) {
+	modules := []Manifest{
+		{Module: "fail2ban", Jailing: &Jailing{Into: "/etc/fail2ban/jail.d/mesh-composed.conf", FilterInto: "/etc/fail2ban/filter.d"}},
+		{Module: "postgres", Jails: []Jail{{Name: "postgres-auth", Failregex: "auth failed from <HOST>", Jail: "port = 5432\nmaxretry = 5"}}},
+	}
+	files := jailsInto(modules, modules[0].Jailing)
+
+	by := map[string]map[string]any{}
+	for _, f := range files {
+		by[f["id"].(string)] = f
+	}
+	jail := by[ComposedJailsID()]
+	if jail == nil || jail["path"] != "/etc/fail2ban/jail.d/mesh-composed.conf" {
+		t.Fatalf("the composed jail file was not written: %v", jail)
+	}
+	body := jail["content"].(string)
+	if !strings.Contains(body, "[postgres-auth]") || !strings.Contains(body, "filter = postgres-auth") ||
+		!strings.Contains(body, "port = 5432") {
+		t.Fatalf("the postgres jail stanza was not composed in:\n%s", body)
+	}
+	filter := by["filter-postgres-auth"]
+	if filter == nil || filter["path"] != "/etc/fail2ban/filter.d/postgres-auth.conf" {
+		t.Fatalf("the jail's filter file was not written: %v", filter)
+	}
+	if !strings.Contains(filter["content"].(string), "failregex = auth failed from <HOST>") {
+		t.Fatalf("the failregex was not written: %v", filter["content"])
+	}
+}
+
+// A holder whose node runs no jail-declaring module still gets the file, empty — so removing the
+// last jail is a change the service restarts on, not a file that vanishes.
+func TestTheComposedJailFileIsWrittenEvenWhenEmpty(t *testing.T) {
+	files := jailsInto([]Manifest{{Module: "fail2ban"}}, &Jailing{Into: "/x", FilterInto: "/f"})
+	if len(files) != 1 || files[0]["id"] != ComposedJailsID() {
+		t.Fatalf("the empty composed jail file was not written alone: %v", files)
+	}
+}
@@ -57,7 +57,7 @@ func machineUsed(content string) []string {
 // the hosts file and the resolver's wildcards are written from, so a file naming the machine's
 // address and the file every other machine reaches it by cannot disagree. Absent, like `at`, when
 // the machine is off the network or the mesh has not placed it.
-func machineFacts(r Resolution, names map[string]string) map[string]string {
+func machineFacts(r Resolution, names map[string]string, meshRange string) map[string]string {
 	out := map[string]string{"name": r.Node}
 	if r.At != "" {
 		out["at"] = r.At
@@ -65,32 +65,59 @@ func machineFacts(r Resolution, names map[string]string) map[string]string {
 			out["address"] = address
 		}
 	}
+	// The private network's whole range — a mesh-wide fact, not this machine's, but named here
+	// because a module cannot know it and sometimes must (an intrusion filter that must never ban a
+	// tunnel peer). Absent when the mesh has no range to give.
+	if meshRange != "" {
+		out["mesh-range"] = meshRange
+	}
+	// The operator's login on this machine and where its home is (novox/hq to-be 29), so a module
+	// that writes operator config names the account and its home rather than a value it cannot know.
+	// Absent when no operator account is known — a headless box a person never logs into.
+	if r.Account != "" {
+		out["account"] = r.Account
+		out["account-home"] = accountHomeOf(r.Account, r.AccountHome)
+	}
 	return out
 }

+// accountHomeOf is where an account's home is: what was stored, or the derived default — /root for
+// root, /home/<account> otherwise. The one place the default is written, so a fact and the store
+// cannot disagree about it.
+func accountHomeOf(account, home string) string {
+	if home != "" {
+		return home
+	}
+	if account == "root" {
+		return "/root"
+	}
+	return "/home/" + account
+}
+
 // machineInto replaces a file's ${machine:…} placeholders with what the mesh knows about the
 // machine the module was assigned to.
 //
 // A key the mesh does not hold is refused, for the same reason a binding's is: left alone, the
 // literal would be written into a configuration file and read as a value.
 func machineInto(resource map[string]any, facts map[string]string, module string) error {
-	if fmt.Sprint(resource["type"]) != "file" {
-		return nil
-	}
-	content, ok := resource["content"].(string)
-	if !ok {
-		return nil
-	}
-	for _, key := range machineUsed(content) {
-		value, has := facts[key]
-		if !has {
-			return fmt.Errorf(
-				"%s has a file that says ${machine:%s}, and this machine says %s",
-				module, key, orNothing(namesOfFacts(facts)))
+	// Content, and now the path and owner too: a module that writes into a person's home names it
+	// with ${machine:account-home} and ${machine:account}, which it cannot know until assigned
+	// (novox/hq to-be 29), the same reason its content names ${machine:address}.
+	for _, field := range []string{"path", "owner", "content"} {
+		s, ok := resource[field].(string)
+		if !ok {
+			continue
+		}
+		for _, key := range machineUsed(s) {
+			value, has := facts[key]
+			if !has {
+				return fmt.Errorf(
+					"%s has a %s that says ${machine:%s}, and this machine says %s",
+					module, field, key, orNothing(namesOfFacts(facts)))
+			}
+			s = strings.ReplaceAll(s, fmt.Sprintf("${machine:%s}", key), value)
+			resource[field] = s
 		}
-		resource["content"] = strings.ReplaceAll(
-			content, fmt.Sprintf("${machine:%s}", key), value)
-		content = resource["content"].(string)
 	}
 	return nil
 }
@@ -103,3 +103,26 @@ func TestAModuleNamesTheAddressBehindItsMachinesName(t *testing.T) {
 		t.Fatalf("a machine off the network was given an address, or refused for another reason: %v", err)
 	}
 }
+
+// The mesh's private range is offered as ${machine:mesh-range}, so a module names it rather than
+// hardcoding a value it cannot know (novox/hq ADR 0112) — the fail2ban ignoreip is the case.
+func TestAModuleNamesTheMeshRange(t *testing.T) {
+	facts := machineFacts(Resolution{Node: "anchor", At: "anchor.internal"},
+		map[string]string{"anchor.internal": "10.10.0.1"}, "10.10.0.0/24")
+	if facts["mesh-range"] != "10.10.0.0/24" {
+		t.Fatalf("the mesh range is not a machine fact: %v", facts)
+	}
+	res := map[string]any{"type": "file", "id": "jail", "content": "ignoreip = 127.0.0.1/8 ${machine:mesh-range}\n"}
+	if err := machineInto(res, facts, "fail2ban"); err != nil {
+		t.Fatal(err)
+	}
+	if got := res["content"].(string); !strings.Contains(got, "10.10.0.0/24") || strings.Contains(got, "${machine:") {
+		t.Fatalf("the mesh range was not written in: %q", got)
+	}
+	// A mesh with no range gives no such fact, and a file that names it is refused rather than
+	// left with a literal placeholder in it.
+	none := machineFacts(Resolution{Node: "anchor"}, nil, "")
+	if _, has := none["mesh-range"]; has {
+		t.Fatal("a mesh with no range still offered one")
+	}
+}
@@ -176,15 +176,29 @@ type Manifest struct {
 	// Requires are names that must be provided by something assigned to the same node.
 	Requires []string `json:"requires,omitempty"`

-	// Emits are the event types this module publishes onto the broker — dotted topic keys, e.g.
-	// "module.umami.site.created". Declared so the mesh knows the event graph; events are
-	// provisioning's lighter sibling — 1:many and broadcast, no credential (novox/hq ADR 0041).
+	// Emits are the events this module publishes, named **locally**: `order.placed`, not a subject
+	// and not a routing key. The mesh derives where it lands (design 29 §1), so reorganising the
+	// subject space leaves this manifest correct. Events are provisioning's lighter sibling — 1:many
+	// and broadcast, no credential (novox/hq ADR 0041).
+	//
+	// A module publishes under its own name only. If the event is about a *role* rather than about
+	// this module, it belongs on that seat, where the name outlives whoever holds it.
+	//
+	// **This said "dotted topic keys, e.g. module.umami.site.created" until 04-ISSUES/127**, which
+	// is the old bus's routing key, and is why every manifest in the catalogue had the same mistake:
+	// nobody was guessing, everybody followed this comment.
 	Emits []string `json:"emits,omitempty"`

-	// Consumes are the event patterns this module subscribes to — topic patterns over module,
-	// mesh and node events alike, e.g. "node.*.joined" or "#" (the audit logger). The runtime
-	// wires the subscription; the module ships the handler. A Consumes for an event nothing on
-	// the mesh Emits is a dangling edge.
+	// Consumes are the events this module reacts to, each naming its emitter and the event:
+	// `billing.order.placed`. `*` stands for one name and `**` for the rest, so `*.download.completed`
+	// is that event from any module and `**` is every event in the mesh.
+	//
+	// Spelled the mesh's way rather than the wire's, for the reason Emits is: the bus the mesh runs
+	// on today spells these `*` and `#`, the one being built spells them `*` and `>`, and a manifest
+	// naming either would stop being true when the wire changed.
+	//
+	// The runtime wires the subscription; the module ships the handler. A Consumes for an event
+	// nothing on the mesh Emits is a dangling edge.
 	Consumes []string `json:"consumes,omitempty"`

 	// Claims are singular resources. Two modules claiming one thing within a scope cannot both
@@ -192,6 +206,47 @@ type Manifest struct {
 	// that every new module would force its predecessors to update.
 	Claims []Claim `json:"claims,omitempty"`

+	// DefinesSeats are the seats this module defines for itself, with their protocols
+	// (novox/hq ADR 0121, ADR 0129). The control plane defines the system seats — `mesh-*` and
+	// `node-*` — and a module may define its own, named outside that namespace, to coordinate its
+	// own instances: the mesh enforces one-holder-per-scope for it without knowing what it means. A
+	// module's declared seat is the only non-system name it may then claim; a claim to a name
+	// neither the mesh nor the module defines is refused.
+	//
+	// **Two lines of work built this at once**, one calling it `Seats` with a protocol and one
+	// `DefinesSeats` without. Same key in the file, so no manifest is affected: this is the trunk's
+	// name with the richer type, because what a role accepts, emits and serves is what lets the mesh
+	// check that a holder answers what its seat promises.
+	DefinesSeats []SeatDeclaration `json:"seats,omitempty"`
+
+	// Uses are seats this module sends to. It names the *seat*, never the module holding it, so
+	// the implementation can be replaced under it and no caller changes. A caller gets publish
+	// on that seat's inbound subjects and nothing else — not its outbound events, and not a
+	// subscription to the queue it writes to (design 29 §2).
+	Uses []string `json:"uses,omitempty"`
+
+	// Prepares says this module has state that must be brought to the shape this version needs
+	// before this version runs, and that the module's own code does it (novox/hq ADR 0135).
+	//
+	// **A word, not an arrangement.** The mesh runs the module's own program in its preparation
+	// mode, in the module's own context — every binding, credential and setting its code receives,
+	// because it *is* its code. Nothing here names a container, a command, a mount or a variable:
+	// the module already said all of that once, and a second copy is a second thing to drift.
+	//
+	// **Declared, never inferred.** The control plane cannot read what is inside an artifact, so a
+	// module that ships a migration and does not say this breaks on its first upgrade. That is
+	// stated in the record rather than guarded here, because nothing mechanical can guard it.
+	Prepares bool `json:"prepares,omitempty"`
+
+	// Tools are the tools this module answers — request and reply, awaited.
+	//
+	// **New, and not `serves`**, which this manifest already uses for the facts a consumer needs
+	// in order to reach a provision. Two meanings under one key would be a footgun in the one
+	// file a module author reads most. Until now a module's tools were known only at runtime,
+	// from MESH_TOOL_MODULES in its image; declaring them is what lets the mesh check that a
+	// module claiming a seat answers what that seat's protocol promises (novox/hq ADR 0118).
+	Tools []string `json:"tools,omitempty"`
+
 	// Capabilities the machine must have. A different field from Requires because the remedy
 	// differs: a missing module can be assigned, and a missing capability means the wrong
 	// machine.
@@ -358,6 +413,14 @@ type Manifest struct {
 	// that could only see its own ports would write a rule set that closed everything else.
 	Filtering *Filtering `json:"filtering,omitempty"`

+	// Jails are the fail2ban jails this module declares for its own service (novox/hq to-be 31).
+	// Written into whichever node runs the module, the same way `listens` become that node's rules.
+	Jails []Jail `json:"jails,omitempty"`
+
+	// Jailing marks the module that composes the node's fail2ban jails — the intrusion-prevention
+	// holder. Like Filtering: one module per node gathers what every module declared and writes it.
+	Jailing *Jailing `json:"jailing,omitempty"`
+
 	// Guards are ports of this module's the mesh refuses on an adopted node except from the
 	// private network and from the machine itself (novox/hq ADR 0100) — the store's port and the
 	// broker's management port. The ports the software uses; the mesh guards where the machine
@@ -366,24 +429,29 @@ type Manifest struct {
 	// firewall does. Ignored on a converged node, whose derived filter already closes them.
 	Guards []int `json:"guards,omitempty"`

-	// Facts are things only the mesh knows, written where this module asks for them.
+	// Facts are things only the mesh knows, written where this module asks for them — in the
+	// module's own format.
 	//
-	// **The graph is the control plane's; how a machine uses it is the module's.** The mesh knows
-	// which machines exist, what they are called and where they are. Making a name resolve, or a
-	// peer reachable, is somebody's software — dnsmasq, a resolver, a VPN — and the mesh has no
-	// business shipping one, choosing which, or knowing its configuration language.
+	// **The graph is the control plane's; the format is the module's.** The mesh knows which
+	// machines exist, what they are called and where they are. Turning that into a name that
+	// resolves, a peer that is reachable, a host a client trusts, is somebody's software — dnsmasq,
+	// a resolver, a VPN, ssh — in its own configuration language, and the mesh has no business
+	// knowing it. So a module gives a path and a template; the mesh renders the roster through it
+	// and owns nothing of what the file says.
 	//
-	// So a module says *put the node names here* and owns everything after that. The same shape as
-	// `filtering`, generalised: a fact, and a path.
+	// This used to be a closed list of fact names, each formatted in Go in the control plane, so a
+	// new consumer meant a new formatter here in the consumer's language. Now the data is the mesh's
+	// and the format is the module's: the two built-in cases — the network module's `/etc/hosts` and
+	// dnsmasq's zones — render through the same template path any module uses, and no format lives
+	// in the control plane at all. See RosterFile for what a template sees.
 	//
 	// It replaces three modules that existed only because computed output needed somewhere to
 	// live — they ran no software, could not be swapped for anything, and appeared in the graph as
 	// modules while being a data channel wearing a costume.
 	//
-	// Keyed by fact name; the names are a closed list, because a module asking for one the mesh
-	// does not compute is asking for something nobody will write, and finding that out on a machine
-	// is worse than being told here.
-	Facts map[string]string `json:"facts,omitempty"`
+	// Keyed by a name the module chooses, which is the rendered file's id (`fact-<name>`) — what a
+	// `restart-on` names to restart when the roster changes.
+	Facts map[string]RosterFile `json:"facts,omitempty"`

 	// Certificate is where this module wants a certificate for its machine's name inside the
 	// mesh, and where the key that goes with it can be found.
@@ -403,6 +471,20 @@ type Manifest struct {
 	// A directory rather than one document for the same reason as above: each value is sealed
 	// separately and the mesh cannot open any of them to build a list.
 	Grants map[string]string `json:"grants,omitempty"`
+
+	// BusUsers is where this module wants the mesh's user list written, and it is only ever
+	// answered for the module holding `mesh-broker`.
+	//
+	// **The mesh writes who may connect; the module owns everything else about its server**
+	// (novox/hq design 25 §4, task 1.7). Ports, TLS paths and a store directory live in this
+	// module's image and its mounts and change when it does, so the module's own configuration
+	// carries them and includes this file. A controller that wrote the whole configuration would
+	// have to be kept in step with a Dockerfile it never sees.
+	//
+	// **Asking for it is not enough to receive it.** This file holds every user's password hash, so
+	// a module that could ask for it could read every credential on the bus — and the claim on
+	// `mesh-broker` is what authorises it, checked from this manifest alone.
+	BusUsers string `json:"bus-users,omitempty"`
 }

 // Build says how to produce this module's artifacts from its source.
@@ -489,6 +571,21 @@ type Artifact struct {
 	// image built from this same module's own repository, the same as every other artifact.
 	Context *ArtifactContext `json:"context,omitempty"`

+	// System is the operating system this artifact is compiled for, for a bundle whose output is a
+	// binary rather than portable code (novox/hq ADR 0142).
+	//
+	// **Named by the artifact, not by the recipe.** A toolchain deliberately accepts nothing from
+	// the module — anything a module could override there it would be writing a Dockerfile to
+	// override — and yet a compiled binary is per operating system, pinned at link time so a host
+	// refuses to touch a machine it was not built for (novox/hq ADR 0005). The way out is that the
+	// target is a property of the artifact: one artifact declared per system, one build each, and
+	// the recipe stays the mesh's.
+	//
+	// Empty for a bundle whose output runs anywhere, which is every interpreted language, and for
+	// every other kind. A bundle in a language that compiles to a binary must say one, because
+	// "compiled for whatever the build machine happened to be" is the fault this exists to prevent.
+	System string `json:"system,omitempty"`
+
 	// Language is what this module's code is written in, for a bundle.
 	//
 	// **Declared, never guessed.** Inferring it from what files happen to be present makes a
@@ -560,8 +657,23 @@ const (
 // on is a fact, and it should be written once.
 const ArtifactStoreProvision = "artifact-store"

-// Listening is one port a module accepts connections on.
+// Listening is one endpoint a module serves: a port it accepts connections on, and what may be said
+// about that port from outside the module.
 type Listening struct {
+	// Name is what this endpoint is called, so an assignment and a route can refer to it as one thing
+	// (novox/hq ADR 0138).
+	//
+	// **Because a port number is not a name.** Three facts have to be said about an endpoint when a
+	// module is assigned — which machine port it lands on, the subdomain a proxy serves it under, and
+	// how far it reaches — and they were said in three places keyed by the port. A module with two
+	// endpoints of different shapes, a web surface behind a proxy and a protocol port clients dial
+	// directly, cannot be configured that way without a reader joining numbers by hand.
+	//
+	// The module's to choose, like the route's label: it names its own parts. Lowercase, and unique
+	// within the module, so a reference to it is unambiguous. Empty is allowed and means an endpoint
+	// nothing refers to by name, which is every endpoint in the catalogue until they are named.
+	Name string `json:"name,omitempty"`
+
 	Port int `json:"port"`
 	// Protocol is "tcp" or "udp". Absent means tcp, which is what almost everything is — and a
 	// field that had to be written every time would be written wrongly some of the time.
@@ -602,6 +714,36 @@ func (l Listening) At() string {
 	return l.Protocol
 }

+// Jail is a fail2ban jail a module declares for its own service (novox/hq to-be 31).
+//
+// **The module names no node and no path** (ADR 0112): it says what a break-in on its service looks
+// like — the failregex — and the jail's own keys (the port it watches, where it logs, how many
+// tries, how long to ban). The mesh writes it into whichever node's fail2ban runs the module, the
+// same way a module's `listens` become that node's firewall rules. A node not running the module
+// has no such jail.
+type Jail struct {
+	// Name is the jail and its filter, e.g. "postgres-auth". One holder of the name per node.
+	Name string `json:"name"`
+	// Failregex is what a failed authentication looks like in the service's log — the filter.
+	Failregex string `json:"failregex"`
+	// Jail is the body of the jail's stanza: the keys under [<name>] the module knows and the mesh
+	// does not — the port it watches, its logpath and backend, maxretry, bantime.
+	Jail string `json:"jail"`
+}
+
+// Jailing says a module composes the node's fail2ban jails — the intrusion-prevention holder. Like
+// Filtering for the firewall: one module gathers what every other module declared and writes it
+// where it owns. Into is the one jail file the stanzas are composed into (so the fail2ban service
+// can restart on a single resource); FilterInto is the directory each jail's filter file goes in.
+type Jailing struct {
+	Into       string `json:"into"`
+	FilterInto string `json:"filter-into"`
+}
+
+// ComposedJailsID is the single jail file the mesh composes every declared jail into, so the
+// fail2ban service names one resource in its restart-on and a jail added or removed reaches it.
+func ComposedJailsID() string { return "composed-jails" }
+
 // Filtering says where a module wants the computed rule set.
 type Filtering struct {
 	// Into is the path to write it to. Whatever loads it is this module's own business — an
@@ -621,7 +763,22 @@ type Certificate struct {

 // CertificateID and AuthorityID are the resource identities of what the mesh issued.
 func CertificateID() string { return "certificate" }
-func AuthorityID() string   { return "certificate-authority" }
+
+// ClaimsSeat says whether this manifest claims one named seat.
+func (m Manifest) ClaimsSeat(seat string) bool {
+	for _, c := range m.Claims {
+		if c.Name == seat {
+			return true
+		}
+	}
+	return false
+}
+
+// BusUsersID names the mesh's composed user list, so it is the same resource across every
+// declaration and a change to it is an update rather than a second file beside the old one — which
+// on a bus reading a directory would be two account lists, and the server would take both.
+func BusUsersID() string  { return "bus-users" }
+func AuthorityID() string { return "certificate-authority" }

 // FilteringID names the computed rule set, so it is the same resource across every declaration
 // and a change to it is an update rather than an addition beside the old one.
@@ -913,6 +1070,28 @@ func ParseManifest(raw []byte) (Manifest, error) {
 		problems = append(problems, fmt.Sprintf(
 			"%q is not a usable slug: lower-case letters, digits, dashes and dots", m.Slug))
 	}
+	// **`amqp` is not a provision, and not a requirement** (novox/hq ADR 0131). A module that wants
+	// messaging wants the mesh's bus — it emits and consumes through the sdk, which the mesh hands the
+	// bus with the module's own credential — and the bus is whatever holds `mesh-broker`, spoken in
+	// whatever that holder speaks. Naming the old wire protocol asks for a specific server, and the
+	// only one that could answer is the one being retired. Refused here so the word cannot come back
+	// through a manifest.
+	for _, offer := range m.Provides {
+		if offer.Name == "amqp" {
+			problems = append(problems, fmt.Sprintf(
+				"%s provides %q, which is not a provision: the mesh's bus is whatever holds "+
+					"mesh-broker, and a module provides mesh-bus to be it (novox/hq ADR 0131)",
+				m.Module, offer.Name))
+		}
+	}
+	for _, r := range m.Requires {
+		if r == "amqp" {
+			problems = append(problems, fmt.Sprintf(
+				"%s requires %q, which is not a provision: a module reaches the mesh's bus through "+
+					"the sdk, and depends on the mesh-broker seat, not on a protocol (novox/hq ADR 0131)",
+				m.Module, r))
+		}
+	}
 	for _, offer := range m.Provides {
 		p := offer.Name
 		if !name.MatchString(p) {
@@ -950,6 +1129,10 @@ func ParseManifest(raw []byte) (Manifest, error) {
 			problems = append(problems, fmt.Sprintf("%s requires itself", m.Module))
 		}
 	}
+	// What it may call an event, and what it may ask to hear (events.go). Checked here because a
+	// module whose event names are wrong installs, starts, connects and reacts to nothing, with
+	// every log line saying it is fine (novox/hq 04-ISSUES/127).
+	problems = append(problems, EventProblems(m)...)
 	wellFormed := true
 	for _, c := range m.Claims {
 		if !name.MatchString(c.Name) {
@@ -970,6 +1153,10 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	if wellFormed {
 		problems = append(problems, claimProblems(m)...)
 	}
+	// What one manifest can be judged on: a declaration's shape, its scope, and the reserved
+	// prefix. Whether a seat anybody names exists, and whether a holder answers for it, are
+	// facts about the catalogue and are checked at registration (CatalogueProblems).
+	problems = append(problems, declaredSeatProblems(m)...)
 	if m.Computed != "" && len(m.Resources) > 0 {
 		// One or the other. A module that both ships files and has them computed would leave
 		// nobody able to say where a given file came from.
@@ -1093,6 +1280,8 @@ func ParseManifest(raw []byte) (Manifest, error) {
 				"%s listens on %d over %q, which is tcp or udp", m.Module, l.Port, p))
 		}
 	}
+	problems = append(problems, endpointNameProblems(m)...)
+	problems = append(problems, RouteProblems(m)...)
 	for _, port := range m.Guards {
 		if port < 1 || port > 65535 {
 			problems = append(problems, fmt.Sprintf(
@@ -1132,6 +1321,17 @@ func ParseManifest(raw []byte) (Manifest, error) {
 				"program that reads what the mesh delivered and reconciles",
 			m.Module, r["id"]))
 	}
+	// **A module that prepares its state must have code the mesh can run** (novox/hq ADR 0135). The
+	// preparation is the module's own program in its preparation mode, so it is derived from the
+	// resource that runs that program — and a module declaring none has asked for something the mesh
+	// cannot compose. Said here, where the manifest is read, rather than by a declaration that
+	// quietly prepares nothing.
+	if m.Prepares && preparationTarget(m) == "" {
+		problems = append(problems, fmt.Sprintf(
+			"%s says it prepares its state, and declares no container running an artifact it built — "+
+				"the preparation is this module's own program, so there has to be one for the mesh to "+
+				"run it in", m.Module))
+	}
 	// **A run-once container is a step the host runs to completion** (novox/hq ADR 0052). It is a
 	// boolean modifier on the container shape — the host runs the container, requires it to exit 0,
 	// and starts whatever the declaration places after it only once it has. A value that is not a
@@ -1506,3 +1706,53 @@ func (m Manifest) undeclaredMounts() []string {
 	}
 	return problems
 }
+
+// endpointName is what an endpoint may be called: lowercase letters, digits and dashes, starting
+// with a letter. The same shape a label has, because both end up in something a person types.
+var endpointName = regexp.MustCompile(`^[a-z][a-z0-9-]*$`)
+
+// endpointNameProblems holds a module's endpoint names to being usable as references (novox/hq ADR
+// 0138).
+//
+// **Unique, because the point of a name is that it identifies one thing.** Two endpoints called the
+// same would make an assignment that configures one silently configure whichever the mesh read last
+// — the shape of fault this repository keeps finding, where a declaration appears to say something
+// and says something else.
+func endpointNameProblems(m Manifest) []string {
+	var problems []string
+	seen := map[string]int{}
+	for _, l := range m.Listens {
+		name := strings.TrimSpace(l.Name)
+		if name == "" {
+			continue
+		}
+		if !endpointName.MatchString(name) {
+			problems = append(problems, fmt.Sprintf(
+				"%s calls the endpoint on port %d %q; a name is lowercase letters, digits and "+
+					"dashes, starting with a letter", m.Module, l.Port, l.Name))
+			continue
+		}
+		if before, already := seen[name]; already {
+			problems = append(problems, fmt.Sprintf(
+				"%s calls both port %d and port %d %q, so anything naming that endpoint could mean "+
+					"either", m.Module, before, l.Port, name))
+			continue
+		}
+		seen[name] = l.Port
+	}
+	return problems
+}
+
+// EndpointPort is the port of the endpoint a module calls this, and whether it has one.
+func EndpointPort(m Manifest, name string) (int, bool) {
+	want := strings.TrimSpace(name)
+	if want == "" {
+		return 0, false
+	}
+	for _, l := range m.Listens {
+		if strings.TrimSpace(l.Name) == want {
+			return l.Port, true
+		}
+	}
+	return 0, false
+}
@@ -0,0 +1,121 @@
+package catalogue
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// **A manifest holds no subject** (novox/hq design 29 §1).
+//
+// A module names its events, tools and seats locally, and the mesh derives where they land. The
+// property that buys: reorganise the subject space and every manifest in the catalogue is still
+// correct. It holds today by construction — nothing reads a subject from a manifest — and a rule
+// held by construction is one a later field breaks quietly, with the symptom appearing as a
+// permission that does not match a subject rather than as a manifest that was wrong.
+func TestNoManifestContainsASubject(t *testing.T) {
+	root := filepath.Join("..", "..", "..", "mesh-catalog", "modules")
+	entries, err := os.ReadDir(root)
+	if err != nil {
+		t.Skipf("catalogue sibling not present: %v", err)
+	}
+
+	// Anything in the mesh's own subject space, and anything shaped like a wire address.
+	subject := regexp.MustCompile(`^(mesh|\$JS)\.[a-zA-Z0-9_*>.-]+$`)
+
+	var found []string
+	var walk func(module string, path string, v any)
+	walk = func(module, path string, v any) {
+		switch t := v.(type) {
+		case string:
+			if subject.MatchString(t) {
+				found = append(found, module+" "+path+" = "+t)
+			}
+		case map[string]any:
+			for k, inner := range t {
+				walk(module, path+"."+k, inner)
+			}
+		case []any:
+			for _, inner := range t {
+				walk(module, path+"[]", inner)
+			}
+		}
+	}
+
+	checked := 0
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		raw, err := os.ReadFile(filepath.Join(root, e.Name(), "module.json"))
+		if err != nil {
+			continue
+		}
+		var m any
+		if err := json.Unmarshal(raw, &m); err != nil {
+			t.Errorf("%s: %v", e.Name(), err)
+			continue
+		}
+		checked++
+		walk(e.Name(), "", m)
+	}
+	if checked == 0 {
+		t.Skip("no manifests read")
+	}
+	if len(found) > 0 {
+		t.Errorf("a manifest names a subject, so reorganising the subject space would mean "+
+			"editing the catalogue:\n  %s", strings.Join(found, "\n  "))
+	}
+	t.Logf("%d manifests hold no subject", checked)
+}
+
+// **Every module's event names are what design 29 says, across the whole catalogue.**
+//
+// The rule above holds by construction and turned out to be weaker than it reads: a manifest holds
+// no subject, and every manifest in the catalogue still held the old bus's routing key, which
+// derives into a namespace nobody owns (novox/hq 04-ISSUES/127). Nothing failed — the services
+// started and none of them reacted. This is the check that was missing.
+func TestEveryManifestsEventNamesAreLocal(t *testing.T) {
+	manifests := theCatalogue(t)
+
+	var problems []string
+	for _, m := range manifests {
+		problems = append(problems, EventProblems(m)...)
+	}
+	if len(problems) > 0 {
+		t.Fatalf("the catalogue holds %d event name(s) the mesh would derive wrongly:\n  %s",
+			len(problems), strings.Join(problems, "\n  "))
+	}
+}
+
+// theCatalogue is every manifest beside this checkout, parsed the way registration parses one.
+func theCatalogue(t *testing.T) []Manifest {
+	t.Helper()
+	root := filepath.Join("..", "..", "..", "mesh-catalog", "modules")
+	entries, err := os.ReadDir(root)
+	if err != nil {
+		t.Skipf("catalogue sibling not present: %v", err)
+	}
+	var out []Manifest
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		raw, err := os.ReadFile(filepath.Join(root, e.Name(), "module.json"))
+		if err != nil {
+			continue
+		}
+		var m Manifest
+		if err := json.Unmarshal(raw, &m); err != nil {
+			t.Fatalf("%s: %v", e.Name(), err)
+		}
+		out = append(out, m)
+	}
+	if len(out) == 0 {
+		t.Skip("no manifests found beside this checkout")
+	}
+	return out
+}
@@ -0,0 +1,141 @@
+package catalogue
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"testing"
+)
+
+// A module version prepares its state before it runs (novox/hq ADR 0135).
+//
+// What the mesh derives is the module's own resource, run once with one word, placed immediately in
+// front of the thing it prepares for. What matters in these tests is that the derivation is a copy
+// rather than a second description: the failure it replaces was a hand-written step repeating six
+// fields of the resource it preceded, each free to drift from it.
+
+func aPreparingModule() Manifest {
+	return Manifest{
+		Module:   "gitea",
+		Prepares: true,
+		Resources: []map[string]any{
+			{"id": "state", "type": "directory", "path": "/var/lib/gitea", "mode": "0700"},
+			{"id": "server", "type": "container", "name": "mesh-gitea-server",
+				"image": "gitea/gitea@" + digest, "ports": []any{"3000:3000"}},
+			{"id": "runtime", "type": "container", "name": "mesh-gitea",
+				"image": ArtifactStoreScheme + "gitea/runtime@" + digest, "network": "host",
+				"env":     map[string]any{"MESH_GITEA_STATE_DIR": "/run/state"},
+				"volumes": []any{"/var/lib/gitea:/run/state:ro"},
+				"ports":   []any{"9000:9000"}},
+		},
+	}
+}
+
+func declaredFor(t *testing.T, m Manifest) []map[string]any {
+	t.Helper()
+	// The manifest as the mesh holds it: a build resolved the module's own artifact into the
+	// reference it recorded, which is also how the composition knows whose code a resource runs.
+	out, err := Resolution{Node: "anchor", Modules: []Manifest{m}}.Declaration(
+		Rendering{ArtifactStore: "anchor.internal:5100"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return out
+}
+
+func idsOf(resources []map[string]any) []string {
+	var ids []string
+	for _, r := range resources {
+		ids = append(ids, fmt.Sprint(r["id"]))
+	}
+	return ids
+}
+
+// The step runs the module's own code, and comes immediately before it — not before the upstream
+// server the module packages, which may be the very thing the state lives in.
+func TestThePreparationRunsTheModulesOwnCodeAndComesRightBeforeIt(t *testing.T) {
+	out := declaredFor(t, aPreparingModule())
+	ids := idsOf(out)
+	at := -1
+	for i, id := range ids {
+		if id == "gitea.runtime-prepare" {
+			at = i
+		}
+	}
+	if at < 0 {
+		t.Fatalf("nothing prepares this module's state: %v", ids)
+	}
+	// A module's name may contain a dot, so a resource's module is everything before the last one —
+	// which the derived id must not add to, or a machine reads the wrong owner from it.
+	if strings.Count("gitea.runtime-prepare", ".") != 1 {
+		t.Fatal("the derived id adds a dot, so what owns it cannot be read from it")
+	}
+	if ids[at+1] != "gitea.runtime" {
+		t.Fatalf("the preparation is not immediately before the module's own code: %v", ids)
+	}
+	for _, id := range ids[:at] {
+		if id == "gitea.runtime" {
+			t.Fatalf("the module's own code runs before its state is prepared: %v", ids)
+		}
+	}
+}
+
+// It is given exactly what the module's own code is given. Asserted field by field against the
+// resource it was derived from, because writing it twice is the fault this replaces.
+func TestThePreparationIsGivenWhatTheModuleIsGiven(t *testing.T) {
+	out := declaredFor(t, aPreparingModule())
+	declared := byID(out)
+	step, workload := declared["gitea.runtime-prepare"], declared["gitea.runtime"]
+	if step == nil || workload == nil {
+		t.Fatalf("expected both, got %v", idsOf(out))
+	}
+	for _, field := range []string{"image", "network", "env", "volumes", "type"} {
+		if fmt.Sprint(step[field]) != fmt.Sprint(workload[field]) {
+			t.Errorf("the preparation's %s is %v and the module's is %v", field, step[field], workload[field])
+		}
+	}
+	if once, _ := step["run-once"].(bool); !once {
+		t.Error("the preparation is not a step, so nothing waits for it and nothing is gated by it")
+	}
+	if fmt.Sprint(step["args"]) != fmt.Sprint([]any{PreparationArgument}) {
+		t.Errorf("the preparation is asked for as %v", step["args"])
+	}
+	if fmt.Sprint(step["name"]) == fmt.Sprint(workload["name"]) {
+		t.Error("the preparation and the workload have one name, so one removes the other")
+	}
+	// A published port cannot be bound twice, and the version being replaced is still running.
+	if _, published := step["ports"]; published {
+		t.Errorf("the preparation publishes a port the running version holds: %v", step["ports"])
+	}
+}
+
+// A module that says nothing about preparing gets nothing, which is most modules.
+func TestAModuleThatPreparesNothingGetsNoStep(t *testing.T) {
+	m := aPreparingModule()
+	m.Prepares = false
+	for _, id := range idsOf(declaredFor(t, m)) {
+		if id == "gitea.runtime-prepare" {
+			t.Fatal("a module that prepares nothing was given a preparation")
+		}
+	}
+}
+
+// A module whose own code the mesh cannot find has nothing to ask, and saying so where the manifest
+// is read beats a declaration that quietly prepares nothing.
+func TestAModuleThatPreparesAndRunsNoneOfItsOwnCodeIsRefused(t *testing.T) {
+	m := Manifest{
+		Module:   "gitea",
+		Prepares: true,
+		Resources: []map[string]any{
+			// Only the upstream server it packages: nothing here runs gitea's own code.
+			{"id": "server", "type": "container", "name": "mesh-gitea-server", "image": "gitea/gitea@" + digest},
+		},
+	}
+	raw, err := json.Marshal(m)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := ParseManifest(raw); err == nil {
+		t.Fatal("a module that prepares its state with nothing of its own to run was accepted")
+	}
+}
@@ -12,5 +12,5 @@ func TestPrintRehearsalRuleset(t *testing.T) {
 	rules := mustFilter(t, Resolution{Modules: []Manifest{
 		{Module: "pub", Listens: []Listening{{Port: 8099, From: FromMesh, Why: "the thing it serves"}}},
 	}}, nil)
-	t.Log("\n" + AsNftables(rules, []string{"192.0.2.20"}, true, nil))
+	t.Log("\n" + AsNftables(rules, []string{"192.0.2.20"}, true, nil, nil, "mesh0"))
 }
@@ -54,7 +54,7 @@ func TestTheShippedNetworkingModulesResolveOnTheirOwn(t *testing.T) {
 	// network is what gives a machine a name, so the provider asks for the node-names fact and
 	// there is nothing else to bring in. A module that ran nothing used to be here.
 	for _, m := range got.Modules {
-		if m.Module == overlay.Name && m.Facts["node-names"] == "" {
+		if m.Module == overlay.Name && m.Facts["node-names"].Path == "" {
 			t.Fatalf("the network's provider does not ask for the names: %+v", m.Facts)
 		}
 	}
@@ -0,0 +1,206 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// a web module with one routed endpoint, the shape almost every routed module in the catalogue has.
+func aRoutedWeb() Manifest {
+	return Manifest{
+		Module:  "web",
+		Listens: []Listening{{Port: 3000, From: FromMesh}},
+		Contributes: map[string]map[string]any{
+			"route": {"label": "app", "port": 3000},
+		},
+	}
+}
+
+func reachSet(reach string) SettingsBy {
+	return SettingsBy{"web": {{From: "node anchor",
+		Values: map[string]any{ReachSetting: map[string]any{"3000": reach}}}}}
+}
+
+// namesFor renders the contribution a routed module makes and returns the two names it carries.
+func namesFor(t *testing.T, m Manifest, settings SettingsBy) (public, internal string) {
+	t.Helper()
+	r := Resolution{Node: "anchor", Modules: []Manifest{m},
+		PublicDomain: "example.test", At: "anchor.internal"}
+	given, err := r.contributions(settings, nil, nil)
+	if err != nil {
+		t.Fatalf("contributions: %v", err)
+	}
+	for _, c := range given["route"] {
+		p, _ := c.Values["name"].(string)
+		i, _ := c.Values["internal-name"].(string)
+		return p, i
+	}
+	t.Fatal("the module contributed no route")
+	return "", ""
+}
+
+// **Nothing said composes both names, exactly as before.** This is the assertion that keeps every
+// mesh already running identical until an assignment speaks, and it is the one that would break first
+// if reach were read where it should not be.
+func TestAnEndpointWithNoReachKeepsBothNames(t *testing.T) {
+	public, internal := namesFor(t, aRoutedWeb(), nil)
+	if public != "app.example.test" || internal != "app.anchor.internal" {
+		t.Fatalf("names are %q and %q, want both composed as before", public, internal)
+	}
+}
+
+// An internal endpoint has an internal name and no public one — so the proxy serves it inside, and
+// the public authority is never asked for a name nobody wanted. This is what "must not be public"
+// could not say before.
+func TestAnInternalEndpointHasNoPublicName(t *testing.T) {
+	public, internal := namesFor(t, aRoutedWeb(), reachSet(ReachInternal))
+	if public != "" {
+		t.Fatalf("an internal endpoint composed the public name %q", public)
+	}
+	if internal != "app.anchor.internal" {
+		t.Fatalf("internal name is %q, want app.anchor.internal", internal)
+	}
+}
+
+// And the mirror: a public endpoint gets the public name and not the internal one, so the mesh's own
+// authority is not asked to certify a name the service is not reached by.
+func TestAPublicEndpointHasNoInternalName(t *testing.T) {
+	public, internal := namesFor(t, aRoutedWeb(), reachSet(ReachPublic))
+	if internal != "" {
+		t.Fatalf("a public endpoint composed the internal name %q", internal)
+	}
+	if public != "app.example.test" {
+		t.Fatalf("public name is %q, want app.example.test", public)
+	}
+}
+
+func TestBothComposesBothNames(t *testing.T) {
+	public, internal := namesFor(t, aRoutedWeb(), reachSet(ReachBoth))
+	if public == "" || internal == "" {
+		t.Fatalf("both should compose both names, got %q and %q", public, internal)
+	}
+}
+
+// **The filter reads the same value — for an endpoint the proxy does not serve.**
+//
+// A routed endpoint's port is how the proxy reaches it and nothing else (ADR 0045): a public service
+// listens from the mesh, only the proxy reaches it, and it is exposed by name. So on a routed
+// endpoint the reach asks for a name and the port keeps what the manifest said.
+func TestAnUnroutedEndpointsPortFollowsItsReach(t *testing.T) {
+	// The same module with its route taken away: now the port is the only way in, so reach governs it.
+	bare := aRoutedWeb()
+	bare.Contributes = nil
+
+	for _, c := range []struct{ reach, want string }{
+		{ReachInternal, FromMesh},
+		{ReachPublic, FromEverywhere},
+		{ReachBoth, FromEverywhere},
+		{ReachMachine, FromMachine},
+	} {
+		r := Resolution{Node: "anchor", Modules: []Manifest{bare}}
+		rules, err := r.Rules(Rendering{Settings: reachSet(c.reach)})
+		if err != nil {
+			t.Fatalf("%s: rules: %v", c.reach, err)
+		}
+		found := false
+		for _, rule := range rules {
+			if rule.Port == 3000 {
+				found = true
+				if rule.From != c.want {
+					t.Fatalf("reach %q made the filter say %q, want %q", c.reach, rule.From, c.want)
+				}
+			}
+		}
+		if !found {
+			t.Fatalf("reach %q produced no rule for the port", c.reach)
+		}
+	}
+}
+
+// **A public name does not open the machine's port**, which is the case that found this.
+//
+// A module whose routed name must be public and whose machine-side port must not be had no way to say
+// so while one value drove both. Under one value it could not be expressed; the port would reopen.
+func TestAPublicNameLeavesARoutedPortAsTheManifestSaid(t *testing.T) {
+	r := Resolution{Node: "anchor", Modules: []Manifest{aRoutedWeb()},
+		PublicDomain: "example.test", At: "anchor.internal"}
+	rules, err := r.Rules(Rendering{Settings: reachSet(ReachPublic)})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, rule := range rules {
+		if rule.Port == 3000 && rule.From != FromMesh {
+			t.Fatalf("a public reach opened a routed port to %q; the proxy is how it is reached",
+				rule.From)
+		}
+	}
+	// And the name it asked for is there, so the reach was not simply ignored.
+	public, internal := namesFor(t, aRoutedWeb(), reachSet(ReachPublic))
+	if public != "app.example.test" || internal != "" {
+		t.Fatalf("names are %q and %q, want the public one only", public, internal)
+	}
+}
+
+// A reach for a port the module does not listen on reaches nothing, and is refused where it is
+// written rather than accepted and ignored.
+func TestAReachForAPortTheModuleDoesNotListenOnIsRefused(t *testing.T) {
+	_, err := Reaches(aRoutedWeb(), []Layer{{From: "node anchor",
+		Values: map[string]any{ReachSetting: map[string]any{"9999": ReachInternal}}}})
+	if err == nil || !strings.Contains(err.Error(), "reaches nothing") {
+		t.Fatalf("a reach naming an undeclared port was accepted: %v", err)
+	}
+}
+
+// A value that is not a reach is refused, and the refusal names the four so a reader is one edit from
+// right. "mesh" is the tempting wrong answer, because that is the filter's word for nearly the same
+// thing.
+func TestAValueThatIsNotAReachIsRefused(t *testing.T) {
+	for _, wrong := range []string{"mesh", "anywhere", "private", "true"} {
+		_, err := Reaches(aRoutedWeb(), []Layer{{From: "node anchor",
+			Values: map[string]any{ReachSetting: map[string]any{"3000": wrong}}}})
+		if err == nil || !strings.Contains(err.Error(), "a reach is") {
+			t.Fatalf("%q was accepted as a reach: %v", wrong, err)
+		}
+	}
+}
+
+// **A port that says both reach and expose is refused.** They say the same thing in different words,
+// and accepting both would have the filter follow one while the names followed the other — the
+// disagreement ADR 0138 exists to remove, reintroduced by the migration away from the older word.
+func TestReachAndExposeForOnePortAreRefused(t *testing.T) {
+	_, err := Reaches(aRoutedWeb(), []Layer{{From: "node anchor", Values: map[string]any{
+		ReachSetting:  map[string]any{"3000": ReachInternal},
+		ExposeSetting: map[string]any{"3000": FromEverywhere},
+	}}})
+	if err == nil || !strings.Contains(err.Error(), "same thing in different") {
+		t.Fatalf("a port set both ways was accepted: %v", err)
+	}
+}
+
+// A path-level refusal carries no port: it is a rule about a name, not an endpoint, and it inherits
+// whatever that name turned out to be. Narrowing the endpoint must not silently drop it.
+func TestARuleWithNoPortIsLeftAlone(t *testing.T) {
+	m := aRoutedWeb()
+	m.ContributesMany = map[string]map[string]map[string]any{
+		"route": {"refused": {"label": "app", "path": "/internal", "deny": true}},
+	}
+	r := Resolution{Node: "anchor", Modules: []Manifest{m},
+		PublicDomain: "example.test", At: "anchor.internal"}
+	given, err := r.contributions(reachSet(ReachInternal), nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var sawDeny bool
+	for _, c := range given["route"] {
+		if deny, _ := c.Values["deny"].(bool); deny {
+			sawDeny = true
+			// It keeps both, because it named no endpoint to be narrowed by.
+			if c.Values["name"] == nil || c.Values["internal-name"] == nil {
+				t.Fatalf("the path rule lost a name it shadows: %v", c.Values)
+			}
+		}
+	}
+	if !sawDeny {
+		t.Fatal("the path rule was dropped")
+	}
+}
@@ -28,6 +28,10 @@ type Node struct {
 	// (novox/hq ADR 0066). A route contribution carries only a label — the subdomain — and the mesh
 	// joins <label>.<public-domain> to make the name it grants, interpreting neither half.
 	PublicDomain string
+	// Account is the operator's login on this machine, AccountHome where its home is (novox/hq
+	// to-be 29). What a home-scoped file is owned by and what ${machine:account} resolves to.
+	Account     string
+	AccountHome string
 }

 // World is what the rest of the mesh already has.
@@ -37,6 +41,11 @@ type Node struct {
 type World struct {
 	// Held is the claims already taken, for the scopes wider than one node.
 	Held []Held
+	// Holdings is every seat whose holder is **on record** (novox/hq ADR 0131): the one assignment
+	// that holds it, chosen by a handover. A seat absent here is held by derivation — the sole
+	// eligible assignment — as it always was. Present, it decides, and any other assignment whose
+	// module could hold the seat is eligible and silent rather than refused.
+	Holdings []Held
 	// Offered is what other nodes provide at mesh scope, and everything needed to use it.
 	Offered map[string][]Provider
 	// Pinned is which node this machine was told to get a provision from, by name. Only consulted
@@ -114,6 +123,11 @@ type Resolution struct {
 	// (novox/hq ADR 0066). Carried from the node so that composing <label>.<public-domain> for a
 	// route contribution needs no store lookup here — the join is a fact about this one machine.
 	PublicDomain string
+	// Account and AccountHome are the operator's login on this machine and where its home is
+	// (novox/hq to-be 29), carried from the node so a home-scoped file's owner and path resolve
+	// here without a store lookup.
+	Account     string
+	AccountHome string

 	// Modules in the order they were resolved: assigned first, then what they pulled in.
 	Modules []Manifest
@@ -541,13 +555,14 @@ func Resolve(catalogue map[string]Manifest, assigned []string, node Node, world
 	}

 	resolution := Resolution{Node: node.Name, At: node.At, PublicDomain: node.PublicDomain,
+		Account: node.Account, AccountHome: node.AccountHome,
 		Because: because, Needs: needs, Unhostable: unhostable}
 	for _, n := range providersFirst(order, catalogue) {
 		resolution.Modules = append(resolution.Modules, catalogue[n])
 	}

 	problems = append(problems, checkCapabilities(resolution.Modules, node)...)
-	claims, claimProblems := checkClaims(resolution.Modules, node, elsewhere)
+	claims, claimProblems := checkClaims(resolution.Modules, node, elsewhere, world.Holdings)
 	problems = append(problems, claimProblems...)
 	problems = append(problems, checkResources(resolution.Modules)...)
 	resolution.Claims = claims
@@ -640,14 +655,35 @@ func checkCapabilities(modules []Manifest, node Node) []string {
 //
 // Within this node's own set, and against what is already held elsewhere for the wider scopes. A
 // claim at mesh scope is the same idea as the mesh's one hub, said once instead of hard-coded.
-func checkClaims(modules []Manifest, node Node, elsewhere []Held) ([]Held, []string) {
+func checkClaims(modules []Manifest, node Node, elsewhere []Held, holdings []Held) ([]Held, []string) {
 	var problems []string
 	var held []Held

+	// onRecord is the recorded holder of a seat, if a handover ever named one.
+	onRecord := func(claim, scope string) (Held, bool) {
+		for _, h := range holdings {
+			hs, ok := SeatNamed(h.Claim)
+			cs, cok := SeatNamed(claim)
+			if ok && cok && hs.Name == cs.Name && h.Scope == scope {
+				return h, true
+			}
+		}
+		return Held{}, false
+	}
+
 	byScope := map[string]map[string]string{} // scope → claim → module
 	for _, m := range modules {
 		for _, c := range m.Claims {
 			scope := c.At()
+			// **A recorded holder settles it before any counting.** An assignment that could hold
+			// the seat but is not the one on record is eligible, and that is all: it is not a second
+			// holder, so it is not refused, and it does not hold (novox/hq ADR 0131). This is what
+			// lets the next holder stand beside the current one until the seat is handed over.
+			if rec, recorded := onRecord(c.Name, scope); recorded {
+				if rec.Node != node.Name || rec.Module != m.Module {
+					continue
+				}
+			}
 			if byScope[scope] == nil {
 				byScope[scope] = map[string]string{}
 			}
@@ -50,7 +50,7 @@ func TestTheResolverForwardsToFixedUpstreamsAndNeverReadsResolvConf(t *testing.T
 		"\nno-resolv\n", "\nserver=1.1.1.1\n", "\nserver=8.8.8.8\n",
 		"\nlisten-address=127.0.0.1\n", "\ninterface=mesh0\n", "\nbind-dynamic\n",
 		"\ndomain-needed\n", "\nbogus-priv\n",
-		"\nconf-file=" + m.Facts[FactNodeZones] + "\n",
+		"\nconf-file=" + m.Facts["node-zones"].Path + "\n",
 	} {
 		if !strings.Contains(config, want) {
 			t.Errorf("the resolver's configuration lacks %q:\n%s", strings.TrimSpace(want), config)
@@ -170,7 +170,7 @@ func TestTwoThingsDecidingWhatAMachineAsksAreRefused(t *testing.T) {
 	if err == nil {
 		t.Fatal("resolv-conf and resolved-split-dns were both assigned to one machine")
 	}
-	if !strings.Contains(err.Error(), "the-resolver-configuration") {
+	if !strings.Contains(err.Error(), "node-resolver-config") {
 		t.Fatalf("the refusal does not say what was claimed: %v", err)
 	}
 }
@@ -0,0 +1,210 @@
+package catalogue
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+	"strings"
+	"text/template"
+)
+
+// What only the mesh knows, written where a module asks for it — in the module's own format.
+//
+// **The graph is the control plane's; the format is the module's.** The mesh knows which machines
+// exist, what they are called and where they are. Turning that into a hosts file, a resolver's
+// zones, an ssh known_hosts is somebody's configuration language, and the mesh has no business
+// knowing it. So the mesh hands the roster to a template the module wrote and renders it; it never
+// learns what the file means.
+//
+// This used to be a closed list of fact names, each with its format written in Go here — a hosts
+// file, a resolver's zones. Every new consumer meant a new formatter in the control plane, in the
+// consumer's configuration language. Now the data is the mesh's and the format is a template the
+// module ships: the two built-in cases (the network module's `/etc/hosts`, dnsmasq's zones) render
+// the same way any module's would, and the control plane holds no format at all.
+//
+// It replaced three modules that existed only because computed output needed somewhere to live —
+// they ran no software, could not be swapped for anything, and appeared in the graph as modules
+// while being a data channel wearing a costume (novox/hq ADR 0040).
+
+// A RosterFile is a file the mesh renders from the roster of machines, in the format the module
+// gives as a Go text/template. The template sees a rosterView: `.Node` (this machine's bare name),
+// `.Suffix` (what its mesh name ends in), and two sets of `{Name, FQDN, Address}` — `.Names`, every
+// name the mesh serves, and `.Machines`, only the nodes of the mesh. Which set a template ranges is
+// how the hq issue 111 distinction is drawn: a container's hosts wants every name; a resolver told
+// the suffix is its own wants only the machines.
+type RosterFile struct {
+	// Path is where on the machine the rendered file goes. Absolute, or it is refused here rather
+	// than discovered as a daemon that reads nothing.
+	Path string `json:"path"`
+	// Template is the module's format, a Go text/template over the rosterView. It is the module's,
+	// not the mesh's: the mesh renders it and does not read it.
+	Template string `json:"template"`
+	// Shared is whether the file the fact goes to belongs to the machine rather than the mesh. When
+	// it does, the mesh owns only a marked region of it and keeps the rest byte for byte (novox/hq
+	// issue 128) — a hosts file is shared, since the distribution's `localhost`, the operator's own
+	// lines and other tools' blocks live there too; a resolver's zones file is not, the mesh owns it
+	// whole. A property of the fact, not of the path: the format determines whether the file is
+	// wholly the mesh's, not where a module happened to ask for it.
+	Shared bool `json:"shared,omitempty"`
+	// Home places the file under this node's operator-account home and chowns it to that account,
+	// rather than at an absolute system path (novox/hq to-be 29). Then Path is home-relative
+	// (`.ssh/config.d/mesh`), resolved against the account's home on the node it is composed for; a
+	// node with no operator account gets no such file. This is how the ssh-client config — every
+	// other node's Host block — is written into a person's home rather than into /etc.
+	Home bool `json:"home,omitempty"`
+}
+
+// rosterView is what a RosterFile's template sees. A closed shape — a template referencing a field
+// the mesh does not compute fails to render here, not on a machine.
+type rosterView struct {
+	Node     string
+	Suffix   string
+	Names    []rosterEntry
+	Machines []rosterEntry
+}
+
+// rosterEntry is one machine as a template sees it: its bare name, its full mesh name, its address,
+// and the operator account to log into it as (novox/hq to-be 29) — empty when none is known, so an
+// ssh Host block template can omit the User line for a machine nobody has an account on.
+type rosterEntry struct {
+	Name    string
+	FQDN    string
+	Address string
+	Account string
+}
+
+// FactsInto renders the roster files a module asked for, as files it will be given.
+//
+// The module owns everything after the file exists: loading it, restarting on it, what a resolver
+// or a client does with it. This only puts it there. `every` is every name the mesh serves;
+// `machines` is only the machines — the two must not be confused (novox/hq 04-ISSUES/111), so both
+// are given and the template chooses.
+func FactsInto(m Manifest, r Resolution, every, machines, accounts map[string]string, suffix string) ([]map[string]any, error) {
+	if len(m.Facts) == 0 {
+		return nil, nil
+	}
+	names := make([]string, 0, len(m.Facts))
+	for name := range m.Facts {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+
+	view := rosterView{
+		Node:     r.Node,
+		Suffix:   strings.TrimPrefix(suffixOr(suffix), "."),
+		Names:    entriesFrom(every, accounts, suffix),
+		Machines: entriesFrom(machines, accounts, suffix),
+	}
+
+	out := make([]map[string]any, 0, len(names))
+	for _, name := range names {
+		fact := m.Facts[name]
+		content, err := renderRoster(fact.Template, view)
+		if err != nil {
+			return nil, fmt.Errorf("%s cannot render %q: %w", m.Module, name, err)
+		}
+		// Where the file goes: under the operator's home and chowned to it (a home fact), or at the
+		// absolute system path it names. A home fact on a machine with no operator account cannot be
+		// placed, and is left out rather than written to nowhere (novox/hq to-be 29).
+		path := fact.Path
+		var owner string
+		if fact.Home {
+			if r.Account == "" {
+				continue
+			}
+			path = accountHomeOf(r.Account, r.AccountHome) + "/" + strings.TrimLeft(fact.Path, "/")
+			owner = r.Account
+		} else if !strings.HasPrefix(fact.Path, "/") {
+			return nil, fmt.Errorf(
+				"%s asks for %q at %q, which is not an absolute path", m.Module, name, fact.Path)
+		}
+		file := map[string]any{
+			"id": "fact-" + name, "type": "file", "path": path, "mode": "0644",
+			"content": content,
+		}
+		if owner != "" {
+			file["owner"] = owner
+		}
+		if fact.Shared {
+			// The host owns only the lines between `# BEGIN mesh <id>` and `# END mesh <id>` and
+			// keeps the rest of the file byte for byte; undeclared, the region goes and nothing else
+			// does (novox/hq issue 128). Every node on the private network receives this, so every
+			// node's host — the controller's own machine included — must be block-aware before a
+			// controller emitting it is rolled out: the order ADR 0102 set for `into: json`.
+			file["into"] = "block"
+		}
+		out = append(out, file)
+	}
+	return out, nil
+}
+
+// renderRoster runs a module's template over the roster. A template that will not parse, or reads
+// a field the mesh does not have, is an error here — where the manifest is — rather than an empty
+// file on a machine.
+func renderRoster(tmpl string, view rosterView) (string, error) {
+	t, err := template.New("roster").Option("missingkey=error").Parse(tmpl)
+	if err != nil {
+		return "", err
+	}
+	var b bytes.Buffer
+	if err := t.Execute(&b, view); err != nil {
+		return "", err
+	}
+	return b.String(), nil
+}
+
+// entriesFrom is a name→address map as sorted roster entries.
+//
+// **A machine with no address is left out.** The mesh has a record for it — somebody added it —
+// and does not yet know where it is, which is the ordinary state between adding a machine and it
+// joining. Writing the name anyway would give a name that resolves to nothing, and a connection to
+// that hangs; leaving it out fails at once and says the name is unknown.
+func entriesFrom(addresses, accounts map[string]string, suffix string) []rosterEntry {
+	out := make([]rosterEntry, 0, len(addresses))
+	for _, name := range sortedNames(addresses) {
+		internal, bare := meshName(name, suffix)
+		// The account is looked up by whichever key the caller keys accounts on — the internal name
+		// or the bare one — so a template gets the right login however the maps were built.
+		account := accounts[name]
+		if account == "" {
+			account = accounts[bare]
+		}
+		out = append(out, rosterEntry{Name: bare, FQDN: internal, Address: addresses[name], Account: account})
+	}
+	return out
+}
+
+// meshName is a machine's internal name and its bare one, from either. The control plane keys
+// the names it hands a resolution by the internal name (`homer.internal`), the same map a
+// container gets as its hosts; a caller that keys by the bare name gets the same answer. The
+// suffix is the one the control plane composed those names with, handed down rather than written
+// here a second time — the alternative was `homer.internal.internal` on every machine.
+func meshName(name, suffix string) (internal, bare string) {
+	dotted := "." + strings.TrimPrefix(suffixOr(suffix), ".")
+	if strings.HasSuffix(name, dotted) {
+		return name, strings.TrimSuffix(name, dotted)
+	}
+	return name + dotted, name
+}
+
+// suffixOr is the suffix given, or the one the mesh composes names with when none was handed down.
+// The one place the default is written, so a fact and a name cannot disagree about it.
+func suffixOr(suffix string) string {
+	if suffix == "" {
+		return "internal"
+	}
+	return suffix
+}
+
+func sortedNames(addresses map[string]string) []string {
+	out := make([]string, 0, len(addresses))
+	for name, at := range addresses {
+		// A machine the mesh cannot place is left out rather than named at nothing.
+		if at == "" {
+			continue
+		}
+		out = append(out, name)
+	}
+	sort.Strings(out)
+	return out
+}
@@ -0,0 +1,260 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// Keyed by the internal name, as the control plane hands them (issue 079). bart has no address —
+// the ordinary state between adding a machine and it joining.
+var threeMachines = map[string]string{"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2", "bart.internal": ""}
+
+// A module says where it wants a roster file and in what format, and is given the rendered file.
+func TestAModuleIsGivenTheFileItAskedFor(t *testing.T) {
+	m := Manifest{Module: "resolver", Facts: map[string]RosterFile{
+		"zones": {Path: "/etc/mesh/zones.conf", Template: "{{range .Machines}}address=/{{.FQDN}}/{{.Address}}\n{{end}}"},
+	}}
+	given, err := FactsInto(m, Resolution{Node: "homer"}, threeMachines, threeMachines, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(given) != 1 {
+		t.Fatalf("expected one file, got %d", len(given))
+	}
+	if given[0]["path"] != "/etc/mesh/zones.conf" || given[0]["type"] != "file" {
+		t.Fatalf("not written where it was asked for: %v", given[0])
+	}
+	// The id is fact-<name>, which is what a restart-on names when the roster changes.
+	if given[0]["id"] != "fact-zones" {
+		t.Fatalf("the file's id is not fact-<name>, so a restart-on cannot find it: %v", given[0]["id"])
+	}
+	if !strings.Contains(given[0]["content"].(string), "address=/homer.internal/10.42.0.1") {
+		t.Fatalf("the file does not hold the fact: %v", given[0]["content"])
+	}
+}
+
+// **A shared fact is written into a region of the machine's file, not over it** (novox/hq issue
+// 128). A hosts file is the machine's — its localhost, the operator's lines, other tools' blocks —
+// so the mesh owns only a marked region (`into: block`); a resolver's zones file is the mesh's
+// whole, and carries no `into`.
+func TestASharedFactIsWrittenIntoARegion(t *testing.T) {
+	roster := map[string]string{"homer.internal": "10.42.0.1"}
+	m := Manifest{Module: "net", Facts: map[string]RosterFile{
+		"node-names": {Path: "/etc/hosts", Template: "{{range .Names}}{{.FQDN}}\n{{end}}", Shared: true},
+		"node-zones": {Path: "/etc/zones", Template: "{{range .Machines}}{{.FQDN}}\n{{end}}"},
+	}}
+	given, err := FactsInto(m, Resolution{Node: "homer"}, roster, roster, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	by := map[string]map[string]any{}
+	for _, f := range given {
+		by[f["path"].(string)] = f
+	}
+	if by["/etc/hosts"]["into"] != "block" {
+		t.Fatalf("a shared fact is not written into a region, so the mesh writes the file whole: %v", by["/etc/hosts"])
+	}
+	if _, has := by["/etc/zones"]["into"]; has {
+		t.Fatalf("an unshared fact was written into a region, so the mesh does not own its own file whole: %v", by["/etc/zones"])
+	}
+}
+
+// **The format is the module's — the mesh renders whatever template it gives.** The same roster
+// through two templates is two entirely different files, and the control plane reads neither.
+func TestTheFormatIsTheModulesOwn(t *testing.T) {
+	roster := map[string]string{"homer.internal": "10.42.0.1"}
+	hostsish := Manifest{Module: "a", Facts: map[string]RosterFile{
+		"f": {Path: "/f", Template: "{{range .Names}}{{.Address}}\t{{.Name}}\n{{end}}"}}}
+	sshish := Manifest{Module: "b", Facts: map[string]RosterFile{
+		"f": {Path: "/f", Template: "{{range .Names}}Host {{.Name}}\n  HostName {{.FQDN}}\n{{end}}"}}}
+
+	h, err := FactsInto(hostsish, Resolution{Node: "homer"}, roster, roster, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	s, err := FactsInto(sshish, Resolution{Node: "homer"}, roster, roster, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if h[0]["content"] != "10.42.0.1\thomer\n" {
+		t.Fatalf("the hosts-shaped template did not render its format: %q", h[0]["content"])
+	}
+	if s[0]["content"] != "Host homer\n  HostName homer.internal\n" {
+		t.Fatalf("the ssh-shaped template did not render its format: %q", s[0]["content"])
+	}
+}
+
+// **A template that will not parse is refused here, not on a machine.** A daemon that starts, reads
+// a file the mesh could not render, and answers nothing is a much worse way to find out.
+func TestABrokenTemplateIsRefusedHere(t *testing.T) {
+	m := Manifest{Module: "resolver", Facts: map[string]RosterFile{
+		"zones": {Path: "/etc/zones", Template: "{{range .Machines}}oops"}}}
+	_, err := FactsInto(m, Resolution{}, nil, nil, nil, "")
+	if err == nil {
+		t.Fatal("a template that does not parse was accepted, so the machine gets an empty file")
+	}
+	if !strings.Contains(err.Error(), "resolver") || !strings.Contains(err.Error(), "zones") {
+		t.Fatalf("the refusal does not say whose template, or which: %v", err)
+	}
+}
+
+// A template reading something the mesh does not compute is refused, not rendered empty. The roster
+// is a closed shape; asking it for the weather fails where the manifest is.
+func TestATemplateReadingWhatTheMeshDoesNotHaveIsRefused(t *testing.T) {
+	m := Manifest{Module: "resolver", Facts: map[string]RosterFile{
+		"zones": {Path: "/etc/zones", Template: "{{.Weather}}"}}}
+	if _, err := FactsInto(m, Resolution{}, nil, nil, nil, ""); err == nil {
+		t.Fatal("a template read a field nobody computes and rendered anyway, silently")
+	}
+}
+
+// A relative path is refused, or a module decides where the mesh writes on a machine.
+func TestAFactMustBeAskedForAtAnAbsolutePath(t *testing.T) {
+	m := Manifest{Module: "resolver", Facts: map[string]RosterFile{
+		"hosts": {Path: "etc/hosts", Template: "x"}}}
+	if _, err := FactsInto(m, Resolution{}, nil, nil, nil, ""); err == nil {
+		t.Fatal("a relative path was accepted")
+	}
+}
+
+// A machine the mesh has a record for and cannot place is left out of the roster.
+//
+// **Not an oversight — the alternative is worse.** A name written with no address resolves to
+// nothing, and a connection to that hangs. Leaving it out fails at once and says the name is
+// unknown, which is a thing somebody can act on.
+func TestAMachineWithNoAddressIsNotInTheRoster(t *testing.T) {
+	m := Manifest{Module: "a", Facts: map[string]RosterFile{
+		"f": {Path: "/f", Template: "{{range .Machines}}{{.Name}}\n{{end}}"}}}
+	given, err := FactsInto(m, Resolution{Node: "homer"}, threeMachines, threeMachines, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(given[0]["content"].(string), "bart") {
+		t.Fatalf("a machine with no address was in the roster, so its name resolves to nothing:\n%s", given[0]["content"])
+	}
+}
+
+// **The names the control plane hands a resolution are already internal names** — `homer.internal`,
+// the same map every container gets as its hosts. A roster entry's FQDN is that name, not it with
+// the suffix appended a second time; either key gives the same entries.
+func TestNamesAreNotSuffixedTwice(t *testing.T) {
+	internal := map[string]string{"homer.internal": "10.42.0.1"}
+	bare := map[string]string{"homer": "10.42.0.1"}
+	tmpl := RosterFile{Path: "/f", Template: "{{range .Machines}}{{.FQDN}} {{.Name}}\n{{end}}"}
+
+	fromInternal, err := FactsInto(Manifest{Module: "a", Facts: map[string]RosterFile{"f": tmpl}}, Resolution{Node: "homer"}, internal, internal, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	fromBare, err := FactsInto(Manifest{Module: "a", Facts: map[string]RosterFile{"f": tmpl}}, Resolution{Node: "homer"}, bare, bare, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fromInternal[0]["content"] != fromBare[0]["content"] {
+		t.Fatalf("the roster differs by how the names were keyed:\n%q\n%q", fromInternal[0]["content"], fromBare[0]["content"])
+	}
+	got := fromInternal[0]["content"].(string)
+	if strings.Contains(got, "internal.internal") || !strings.Contains(got, "homer.internal homer") {
+		t.Fatalf("the entry carries a doubled suffix or the wrong bare name:\n%s", got)
+	}
+}
+
+// The suffix the control plane composed the names with is the one a template sees — an operator who
+// chose another does not get `.internal`. `.Suffix` is the bare form, and FQDNs carry it.
+func TestTheSuffixIsCarriedAsComposed(t *testing.T) {
+	names := map[string]string{"homer.lan": "10.42.0.1"}
+	m := Manifest{Module: "a", Facts: map[string]RosterFile{
+		"f": {Path: "/f", Template: "local=/{{.Suffix}}/\n{{range .Machines}}{{.FQDN}}\n{{end}}"}}}
+	given, err := FactsInto(m, Resolution{Node: "homer"}, names, names, nil, "lan")
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := given[0]["content"].(string)
+	if !strings.Contains(got, "local=/lan/") || strings.Contains(got, "internal") {
+		t.Fatalf("the operator's suffix was not carried, so its names would be wrong:\n%s", got)
+	}
+	if !strings.Contains(got, "homer.lan") {
+		t.Fatalf("the FQDN does not carry the operator's suffix:\n%s", got)
+	}
+}
+
+// novox/hq 04-ISSUES/111: a template is given both sets and chooses. `.Names` is every name the mesh
+// serves — the machines and the names it was told to route; `.Machines` is only the machines. A
+// container's hosts wants every name so a routed name resolves to the machine serving it; a resolver
+// told the suffix is its own wants only the machines, or a routed name written there with the suffix
+// is a name nobody will ever ask for, standing beside the machines and looking as real.
+func TestATemplateChoosesMachinesOrEveryName(t *testing.T) {
+	machines := map[string]string{"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2"}
+	every := map[string]string{
+		"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2",
+		"drive.example.test": "10.42.0.1", "git.example.test": "10.42.0.2",
+	}
+	m := Manifest{Module: "resolver", Facts: map[string]RosterFile{
+		"zones": {Path: "/etc/zones", Template: "{{range .Machines}}{{.FQDN}}\n{{end}}"},
+		"hosts": {Path: "/etc/hosts", Template: "{{range .Names}}{{.FQDN}}\n{{end}}"},
+	}}
+	given, err := FactsInto(m, Resolution{Node: "homer"}, every, machines, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	by := map[string]string{}
+	for _, f := range given {
+		by[f["path"].(string)] = f["content"].(string)
+	}
+
+	zones := by["/etc/zones"]
+	for _, served := range []string{"drive.example.test", "git.example.test"} {
+		if strings.Contains(zones, served) {
+			t.Fatalf("a template over .Machines saw %q, a name the mesh serves rather than a machine:\n%s", served, zones)
+		}
+	}
+	if !strings.Contains(zones, "homer.internal") {
+		t.Fatalf("a template over .Machines did not see the machines:\n%s", zones)
+	}
+
+	hosts := by["/etc/hosts"]
+	for _, name := range []string{"homer.internal", "drive.example.test", "git.example.test"} {
+		if !strings.Contains(hosts, name) {
+			t.Fatalf("a template over .Names did not see %q, so a container would not resolve it:\n%s", name, hosts)
+		}
+	}
+}
+
+// A home fact is placed under the operator account's home and chowned to it, and its template sees
+// each node's account (novox/hq to-be 29) — the ssh-client config is the case.
+func TestAHomeFactIsPlacedUnderTheAccountsHomeAndOwnedByIt(t *testing.T) {
+	names := map[string]string{"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2"}
+	accounts := map[string]string{"homer": "jo", "marge": "jo"}
+	m := Manifest{Module: "ssh-client", Facts: map[string]RosterFile{
+		"ssh-config": {Path: ".ssh/config.d/mesh", Home: true,
+			Template: "{{range .Names}}Host {{.Name}}\n  HostName {{.FQDN}}\n  User {{.Account}}\n{{end}}"}}}
+	given, err := FactsInto(m, Resolution{Node: "homer", Account: "jo"}, names, names, accounts, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f := given[0]
+	if f["path"] != "/home/jo/.ssh/config.d/mesh" {
+		t.Fatalf("the home fact was not placed under the account's home: %v", f["path"])
+	}
+	if f["owner"] != "jo" {
+		t.Fatalf("the home fact is not owned by the account: %v", f["owner"])
+	}
+	if !strings.Contains(f["content"].(string), "Host marge\n  HostName marge.internal\n  User jo") {
+		t.Fatalf("the config does not name the peer's account:\n%s", f["content"])
+	}
+}
+
+// A machine with no operator account gets no home fact — it cannot be placed, so it is left out
+// rather than written to nowhere.
+func TestAHomeFactIsSkippedWhereThereIsNoAccount(t *testing.T) {
+	names := map[string]string{"homer.internal": "10.42.0.1"}
+	m := Manifest{Module: "ssh-client", Facts: map[string]RosterFile{
+		"ssh-config": {Path: ".ssh/config", Home: true, Template: "x"}}}
+	given, err := FactsInto(m, Resolution{Node: "homer"}, names, names, nil, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(given) != 0 {
+		t.Fatalf("a home fact was placed on a machine with no operator account: %v", given)
+	}
+}
@@ -13,7 +13,6 @@ func TestASeatPlaceholderAnswersWhereThisMachinePutTheHolder(t *testing.T) {
 		"type": "container", "id": "server", "name": "mesh-controller",
 		"env": map[string]any{
 			"MESH_STORE_INVENTORY_PORT": "${seat:mesh-store:5432}",
-			"MESH_BROKER_AMQP_PORT":     "${seat:mesh-broker:5672}",
 			"MESH_BROKER_ADDRESS_PORT":  "${seat:mesh-broker:5671}",
 			"MESH_STORE_INVENTORY_FILE": "/run/secrets/inventory",
 		},
@@ -27,7 +26,6 @@ func TestASeatPlaceholderAnswersWhereThisMachinePutTheHolder(t *testing.T) {
 	env := control["env"].(map[string]any)
 	for key, want := range map[string]string{
 		"MESH_STORE_INVENTORY_PORT": "6852",
-		"MESH_BROKER_AMQP_PORT":     "5679",
 		"MESH_BROKER_ADDRESS_PORT":  "5671",
 		"MESH_STORE_INVENTORY_FILE": "/run/secrets/inventory",
 	} {
@@ -146,7 +144,6 @@ func TestTheControlPlanesOwnAddressesFollowTheNodesPorts(t *testing.T) {
 		"MESH_STORE_INVENTORY_PORT":   "6852",
 		"MESH_STORE_IDENTITY_PORT":    "6852",
 		"MESH_STORE_LICENCES_PORT":    "6852",
-		"MESH_BROKER_AMQP_PORT":       "5679",
 		"MESH_BROKER_MANAGEMENT_PORT": "15673",
 		"MESH_BROKER_ADDRESS_PORT":    "5671",
 	} {
@@ -164,7 +161,7 @@ func TestTheControlPlanesOwnAddressesFollowTheNodesPorts(t *testing.T) {
 		t.Fatal(err)
 	}
 	env, _ = fileNamed(out, "mesh-controller.server")["env"].(map[string]any)
-	if env["MESH_STORE_INVENTORY_PORT"] != "" || env["MESH_BROKER_AMQP_PORT"] != "" {
+	if env["MESH_STORE_INVENTORY_PORT"] != "" {
 		t.Errorf("with no settings, the control plane is told %v", env)
 	}
 }
@@ -175,7 +172,6 @@ var SeatPorts = map[string]string{
 	"MESH_STORE_INVENTORY_PORT":   "${seat:mesh-store:5432}",
 	"MESH_STORE_IDENTITY_PORT":    "${seat:mesh-store:5432}",
 	"MESH_STORE_LICENCES_PORT":    "${seat:mesh-store:5432}",
-	"MESH_BROKER_AMQP_PORT":       "${seat:mesh-broker:5672}",
 	"MESH_BROKER_MANAGEMENT_PORT": "${seat:mesh-broker:15672}",
 	"MESH_BROKER_ADDRESS_PORT":    "${seat:mesh-broker:5671}",
 }
@@ -27,40 +27,148 @@ type Seat struct {
 	// provision may only be held by a module providing it at the seat's scope, and its holder is
 	// what a requirement for that provision resolves to when several modules provide it.
 	Delivers string
+	// Accepts, Emits and Serves are the protocol of the role, as local verbs — the same three a
+	// module declares for a seat of its own (novox/hq ADR 0118), and empty for most of these: a seat
+	// is usually about who does a job and not about what may be said to them.
+	//
+	// **Named here so the mesh has no role it cannot describe** (ADR 0121). Without them a build
+	// machine had three audiences for one outcome and nothing derived a grant for any of them, and an
+	// event about a role had nowhere to live but the namespace of whichever module held that role
+	// today — which the bus refuses, because a namespace belongs to who it is named for.
+	Accepts []string
+	Emits   []string
+	Serves  []string
 	// Decision is the record that made it a seat.
 	Decision string
 }

-// seats is the whole set, in the order a person reads it: the mesh's own, then a node's.
-var seats = []Seat{
-	{Name: "mesh-controller", Scope: ScopeMesh, Decision: "novox/hq ADR 0079"},
+// defaultSeats is the set the mesh ships with — the seed for the control plane's seat table and the
+// fallback when it has none (novox/hq ADR 0122). It is the one place the closed set 0110 defines is
+// written; the store's table is seeded from it and thereafter is the live, editable copy.
+//
+// In the order a person reads it: the mesh's own, then a node's.
+var defaultSeats = []Seat{
+	// The control plane states what it did under the seat it holds (novox/hq ADR 0134): a role's
+	// events belong to the role, so they keep their address while the holder is replaced. No accepts,
+	// so no work queue is raised for it — only what its holder may say.
+	{Name: "mesh-controller", Scope: ScopeMesh, Decision: "novox/hq ADR 0079",
+		Emits: []string{"applied", "refused", "built-before"}},
 	{Name: "mesh-store", Scope: ScopeMesh, Delivers: "postgres-database", Decision: "novox/hq ADR 0079"},
-	{Name: "mesh-broker", Scope: ScopeMesh, Delivers: "amqp", Decision: "novox/hq ADR 0079"},
+	// **Delivers the mesh's own bus, not `amqp`.** Those were the same word until
+	// ADR 0127 separated them: `amqp` is a backing service a module may require, and this seat is
+	// the mesh's own transport. ADR 0128 then made that connection something a module requires
+	// rather than receives ambiently — 23 of the catalogue's modules never speak, and an ambient
+	// connection would mint a credential for each.
+	{Name: "mesh-broker", Scope: ScopeMesh, Delivers: "mesh-bus", Decision: "novox/hq ADR 0079"},
 	{Name: "the-artifact-store", Scope: ScopeMesh, Delivers: "artifact-store", Decision: "novox/hq ADR 0075"},
-	{Name: "the-catalogue", Scope: ScopeMesh, Decision: "novox/hq ADR 0110"},
+	{Name: "mesh-catalog", Scope: ScopeMesh, Decision: "novox/hq ADR 0121"},
+	// Deferred renames (novox/hq ADR 0121): these deliver a provision, so renaming them is a
+	// delivering-seat migration with a mesh-wide cascade if a holder stops resolving mid-flight.
+	// They keep their names until that migration is done deliberately, apart from the node-* pass.
 	{Name: "npm-package-registry", Scope: ScopeMesh, Delivers: "npm-package-registry", Decision: "novox/hq ADR 0109"},
 	{Name: "git", Scope: ScopeMesh, Delivers: "git", Decision: "novox/hq ADR 0111"},
-	{Name: "the-build-machine", Scope: ScopeNode, Decision: "novox/hq ADR 0110"},
-	{Name: "the-dns-port", Scope: ScopeNode, Decision: "novox/hq ADR 0110"},
-	{Name: "the-intrusion-prevention", Scope: ScopeNode, Decision: "novox/hq ADR 0110"},
-	{Name: "the-packet-filter", Scope: ScopeNode, Decision: "novox/hq ADR 0110"},
+	// A build is work submitted to this role and its outcome is the role's own event (ADR 0129).
+	// One publish reaches whoever asked, the controller that records it, and the catalogue that
+	// places it in the graph — what the old bus's shared exchange did for free.
+	{Name: "mesh-build-machine", Scope: ScopeMesh,
+		Accepts: []string{"build"}, Emits: []string{"built"}, Decision: "novox/hq ADR 0121"},
+	{Name: "node-dns-resolver", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
+	{Name: "node-intrusion-prevention", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
+	{Name: "node-packet-filter", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
+	// Deferred (novox/hq ADR 0121): renaming to mesh-private-network is a scope + server/client
+	// model change, not a rename, so it stays until that is built.
 	{Name: "the-private-network", Scope: ScopeNode, Decision: "novox/hq ADR 0110"},
-	{Name: "the-resolver-configuration", Scope: ScopeNode, Decision: "novox/hq ADR 0110"},
-	{Name: "the-showcase", Scope: ScopeNode, Decision: "novox/hq ADR 0110"},
+	{Name: "node-resolver-config", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
+	// The program that manages the machine's own network. It delivers nothing: its holder only
+	// keeps the manager and the mesh from contradicting each other — the resolver file left to the
+	// mesh, the private network's interface left alone — and never declares a link, an address or
+	// a wireless network, because the link is the only channel a fix could arrive on. A seat
+	// rather than a condition in the resolver's module, so a machine running two managers is
+	// refused at assignment instead of found by the resolver being rewritten (novox/hq ADR 0117).
+	{Name: "node-uplink", Scope: ScopeNode, Decision: "novox/hq ADR 0117"},
 }

+// A system seat name is the control plane's namespace: `mesh-*` for a mesh-wide role, `node-*` for
+// a per-node one (novox/hq ADR 0121). A claim to a system name the mesh does not define is refused;
+// any other name is a module's own to define and claim. Some of the mesh's own seats predate this
+// convention and are not yet renamed (git, npm-package-registry, the-artifact-store,
+// the-private-network) — those are in the set, so they resolve by name, not by prefix.
+func isSystemSeatName(name string) bool {
+	return strings.HasPrefix(name, "mesh-") || strings.HasPrefix(name, "node-")
+}
+
+// seats is the working set the lookups read. It starts as the compiled defaults and is replaced by
+// what the control plane loaded from its store (novox/hq ADR 0122), so a change to the set is a
+// change to data, not to this code.
+var seats = defaultSeats
+
+// DefaultSeats is the set the mesh ships with, for seeding the store's seat table.
+func DefaultSeats() []Seat { return append([]Seat(nil), defaultSeats...) }
+
+// UseSeats replaces the working set with the one the control plane read from its store.
+//
+// **Empty is ignored on purpose.** A store that has not been seeded yet — or one that could not be
+// read — must leave the compiled defaults in force rather than emptying the set: an empty set would
+// refuse every claim and could stop the control plane composing at all, which is a far worse failure
+// than running on the set the binary shipped with. So the store can only ever *replace* the set with
+// a non-empty one, never erase it.
+func UseSeats(s []Seat) {
+	if len(s) == 0 {
+		return
+	}
+	// **The store's rows carry no protocol yet, and the protocol is what the bus is derived
+	// from.** ADR 0129 gives a seat what it accepts, emits and serves; ADR 0122 moved the set into
+	// a table that has name, scope, delivers and decision and nothing else, and the columns for
+	// the rest are not there yet. So a row replacing a compiled entry would silently drop the
+	// protocol, and the roles' work queues would never be raised — found live as "no response
+	// from stream" the first time a build was submitted over the new bus (2026-09-28). Until the
+	// table gains the columns, a row without a protocol keeps the compiled one of the same name.
+	byName := map[string]Seat{}
+	for _, d := range defaultSeats {
+		byName[d.Name] = d
+	}
+	merged := make([]Seat, 0, len(s))
+	for _, row := range s {
+		if len(row.Accepts)+len(row.Emits)+len(row.Serves) == 0 {
+			if d, known := byName[row.Name]; known {
+				row.Accepts, row.Emits, row.Serves = d.Accepts, d.Emits, d.Serves
+			}
+		}
+		merged = append(merged, row)
+	}
+	seats = merged
+}
+
+// aliases maps a seat's former names to its current canonical name (novox/hq ADR 0122). Loaded from
+// the store alongside the set, so a reference to a name a seat used to have — a manifest's claim, a
+// held record — still resolves to it after a rename, and nothing downstream has to change.
+var aliases = map[string]string{}
+
+// UseAliases replaces the former-name map with the one the control plane read from its store. Empty
+// is fine and ordinary: a mesh whose seats have never been renamed has no aliases.
+func UseAliases(m map[string]string) { aliases = m }
+
 // Seats is every seat the mesh defines, in reading order.
 func Seats() []Seat {
 	return append([]Seat(nil), seats...)
 }

-// SeatNamed is the seat a claim names, if the mesh defines one.
+// SeatNamed is the seat a name refers to, whether that is its current name or one it used to have
+// (novox/hq ADR 0122). A former name resolves to the seat's canonical row, so a rename breaks no
+// reference to the old name.
 func SeatNamed(name string) (Seat, bool) {
 	for _, s := range seats {
 		if s.Name == name {
 			return s, true
 		}
 	}
+	if canonical, aliased := aliases[name]; aliased {
+		for _, s := range seats {
+			if s.Name == canonical {
+				return s, true
+			}
+		}
+	}
 	return Seat{}, false
 }

@@ -77,35 +185,93 @@ func SeatDelivering(provision string) (Seat, bool) {
 	return Seat{}, false
 }

-// claimProblems is what is wrong with a manifest's claims against the set.
+// claimProblems is what is wrong with a manifest's claims and the seats it defines.
 //
-// Three refusals, each naming the seat: a seat the mesh does not define, a seat claimed at another
-// scope, and a seat that delivers a provision claimed by a module that does not provide it — which
-// would make the module the mesh's answer for something it cannot answer.
+// A claim is one of three things (novox/hq ADR 0121): a **system seat** the control plane defines —
+// checked for scope and, if it delivers a provision, that the claimant provides it; a **system name
+// the mesh does not define** (`mesh-*`/`node-*`) — refused, because that namespace is the control
+// plane's; or a **module-defined seat** — valid only when this manifest also declares it, since a
+// module may coordinate its own instances through a seat of its own but may not invent one by
+// claiming it. A module's own seat declaration may not sit in the system namespace or shadow a
+// system seat.
 func claimProblems(m Manifest) []string {
 	var problems []string
-	for _, c := range m.Claims {
-		seat, known := SeatNamed(c.Name)
-		if !known {
+
+	defined := map[string]SeatDeclaration{}
+	for _, d := range m.DefinesSeats {
+		if _, isSystem := SeatNamed(d.Name); isSystem || isSystemSeatName(d.Name) {
 			problems = append(problems, fmt.Sprintf(
-				"%s claims %q, which is not a seat this mesh defines (novox/hq ADR 0110) — "+
-					"the seats are: %s", m.Module, c.Name, seatNames()))
+				"%s defines a seat %q in the mesh's own namespace; a module's seat is named outside "+
+					"mesh-*/node-* (novox/hq ADR 0121)", m.Module, d.Name))
 			continue
 		}
-		if c.At() != seat.Scope {
-			problems = append(problems, fmt.Sprintf(
-				"%s claims %s at scope %q, and %s is a %s seat",
-				m.Module, c.Name, c.At(), c.Name, seat.Scope))
+		defined[d.Name] = d
+	}
+
+	for _, c := range m.Claims {
+		if _, known := SeatNamed(c.Name); known {
+			// **A seat's scope and what it delivers are not judged here** (novox/hq ADR 0122).
+			// This function runs wherever a manifest is parsed, and one of those places is the
+			// build machine, which has no store: there, `SeatNamed` answers from the set the
+			// binary shipped with, so a build would be refused for disagreeing with a compiled
+			// copy of data the control plane owns. Exactly that happened — a holder of the bus
+			// seat was refused for not providing what a stale compiled row said the seat
+			// delivered, while the store's own row said otherwise.
+			//
+			// Both checks moved to CatalogueProblems, which only ever runs in the control plane,
+			// after UseSeats has replaced the set with the store's.
+			continue
 		}
-		if seat.Delivers != "" && !providesAt(m, seat.Delivers, seat.Scope) {
+		if isSystemSeatName(c.Name) {
 			problems = append(problems, fmt.Sprintf(
-				"%s claims %s, whose holder answers for %q, and %s does not provide %q at %s scope",
-				m.Module, c.Name, seat.Delivers, m.Module, seat.Delivers, seat.Scope))
+				"%s claims %q, which is a seat in the mesh's own namespace (mesh-*/node-*) that it "+
+					"does not define (novox/hq ADR 0121) — the seats are: %s", m.Module, c.Name, seatNames()))
+			continue
+		}
+		d, ours := defined[c.Name]
+		if !ours {
+			// **A claim on a seat this manifest does not declare is not the parser's to judge.**
+			// A module may hold a seat another module declared — that is why ADR 0126 has callers
+			// name the seat and not its provider, so an implementation can be replaced without
+			// touching a caller. Whether the seat exists is a fact about the whole catalogue, so
+			// the refusal is at registration, where every declaration is in view
+			// (`CatalogueProblems`: "which no module declares and the mesh does not define").
+			continue
+		}
+		if c.At() != d.At() {
+			problems = append(problems, fmt.Sprintf(
+				"%s claims its own seat %s at scope %q, having declared it at %q",
+				m.Module, c.Name, c.At(), d.At()))
 		}
 	}
 	return problems
 }

+// CanHold is why a module could not hold a seat, or nothing: its definition must claim the seat at
+// the seat's scope, and provide what the seat delivers, if it delivers anything. The seat is the
+// store's row, so this is judged only where the store's set is loaded — at registration and in the
+// handover command (novox/hq ADR 0131), never in the parser.
+func CanHold(m Manifest, seat Seat) error {
+	var claimed *Claim
+	for i := range m.Claims {
+		if hs, ok := SeatNamed(m.Claims[i].Name); ok && hs.Name == seat.Name {
+			claimed = &m.Claims[i]
+		}
+	}
+	if claimed == nil {
+		return fmt.Errorf("%s does not claim %s", m.Module, seat.Name)
+	}
+	if claimed.At() != seat.Scope {
+		return fmt.Errorf("%s claims %s at scope %q, and %s is a %s seat",
+			m.Module, seat.Name, claimed.At(), seat.Name, seat.Scope)
+	}
+	if seat.Delivers != "" && !providesAt(m, seat.Delivers, seat.Scope) {
+		return fmt.Errorf("%s claims %s, whose holder answers for %q, and %s does not provide %q at %s scope",
+			m.Module, seat.Name, seat.Delivers, m.Module, seat.Delivers, seat.Scope)
+	}
+	return nil
+}
+
 func providesAt(m Manifest, provision, scope string) bool {
 	for _, o := range m.Provides {
 		if o.Name == provision && o.At() == scope {
@@ -136,7 +302,10 @@ func HolderAmong(provision string, providers []Provider, held []Held) (Provider,
 		return Provider{}, false
 	}
 	for _, h := range held {
-		if h.Claim != seat.Name || h.Scope != seat.Scope {
+		// Resolve the held claim to a seat rather than comparing names, so a record naming a seat's
+		// former name still matches it after a rename (novox/hq ADR 0122).
+		hs, ok := SeatNamed(h.Claim)
+		if !ok || hs.Name != seat.Name || h.Scope != seat.Scope {
 			continue
 		}
 		for _, p := range providers {
@@ -147,3 +316,18 @@ func HolderAmong(provision string, providers []Provider, held []Held) (Provider,
 	}
 	return Provider{}, false
 }
+
+// SeatsWithAProtocol are the mesh's own seats that say something about what may be said to them or by
+// them, which is the set the bus derives streams, consumers and permissions from.
+//
+// Most of the set is not here, and that is the ordinary case: a seat saying only who does a job grants
+// nothing on the bus and needs no queue.
+func SeatsWithAProtocol() []Seat {
+	var out []Seat
+	for _, s := range seats {
+		if len(s.Accepts) > 0 || len(s.Emits) > 0 || len(s.Serves) > 0 {
+			out = append(out, s)
+		}
+	}
+	return out
+}
--- a/Show More
+++ b/Show More