Two machines holding the build role share one queue, and neither is handed an ask while busy (hq ADR 0190)

Against a real bus: three asks, two machines; each takes one, the third waits until one is free
and then goes to that one; a machine that stops leaves nothing taken twice. The redelivery of an
ask a dead machine held is the ack wait's, proven by the hand-back test beside this one.

And the order a live mesh switches over in, written where the role is named: queued builds first,
then this controller, then build-agent assigned where machines build, then the builder and the old
seat's stream forgotten.

cmd/mesh-controller/adoption.go

@@ -95,7 +95,7 @@ func showFiltering(f inventory.Filtering, adopted bool) {
 		case fw.Active:
 			fmt.Printf("  found firewall    %s is ACTIVE on this converged machine; the next apply retires it again\n", fw.Kind)
 		case fw.RetiredBy == "removed":
-			fmt.Printf("  found firewall    %s, removed: the mesh's filter is what filters this machine (novox/hq ADR 0175)\n", fw.Kind)
+			fmt.Printf("  found firewall    %s, removed: the mesh's filter is what filters this machine (novox/hq ADR 0180)\n", fw.Kind)
 		case fw.RetiredBy == inventory.FilterMesh || fw.RetiredBy == "mesh":
 			fmt.Printf("  found firewall    %s, retired by the mesh; its configuration stays on disk\n", fw.Kind)
 		case fw.RetiredBy != "":

cmd/mesh-controller/build.go

@@ -522,6 +522,8 @@ func takeIn(ctx context.Context, inv *inventory.Inventory, result link.BuildResu
 	recorded := inventory.Source{
 		Repository: result.Repository, Path: result.Path, Ref: result.Ref,
 		BuiltFrom: result.Commit, Head: result.Commit,
+		// What it stood on, so registration can judge a built manifest's base (to-be 38 WP2.4).
+		Against: kept.Against,
 	}
 	if result.Source != nil && result.Source.Seat != "" {
 		recorded.Repository, recorded.Seat = result.Source.Repository, result.Source.Seat

cmd/mesh-controller/modules.go

@@ -557,7 +557,7 @@ func issueOnTheNewBus(ctx context.Context, inv *inventory.Inventory, m catalogue
 
 	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,
+		Username: user, Kind: busKindOf(m.Module), Node: node, Module: m.Module,
 	})
 	if err != nil {
 		return err
@@ -577,6 +577,16 @@ func issueOnTheNewBus(ctx context.Context, inv *inventory.Inventory, m catalogue
 	return issueWith(ctx, inv, m, node, busAddress, known, reachable, user, password)
 }
 
+// busKindOf is what a module's bus user is recorded as: the node's tool runtime where the module is
+// the runtime (novox/hq ADR 0175), a module otherwise. The username is the same either way — the
+// runtime is issued through this same path — and the kind is what a reader of the records sees.
+func busKindOf(module string) string {
+	if module == catalogue.RuntimeModule {
+		return inventory.BusNodeTools
+	}
+	return inventory.BusModule
+}
+
 // 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

cmd/mesh-controller/order_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"reflect"
 	"strings"
 	"testing"
 	"time"
@@ -191,7 +192,7 @@ func TestWhatAHandedOverModuleRecordsAboutItsSource(t *testing.T) {
 		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{}) {
+	if from, err := whereItComesFrom("", "", "", "", false); err != nil || !reflect.DeepEqual(from, inventory.Source{}) {
 		t.Fatalf("a manifest handed over with no provenance was refused: %+v, %v", from, err)
 	}
 	for _, c := range []struct {

cmd/mesh-controller/push.go

@@ -131,10 +131,17 @@ func serve(ctx context.Context) error {
 
 	// And the mesh's own verbs, as the seat this control plane holds (novox/hq ADR 0154). Served
 	// from the store's row, so what the seat declares is what is answered.
-	handlers, err := seatToolHandlers()
+	handlers, behind, err := seatToolHandlers()
 	if err != nil {
 		return err
 	}
+	if len(behind) > 0 {
+		// Said once, loudly, and then served anyway (novox/hq ADR 0185): the mesh keeps answering
+		// while whatever put an older control plane here is undone.
+		fmt.Printf("this control plane is behind the %s row: it cannot run %s. "+
+			"Those answer the reason when called; everything else is served as usual\n",
+			catalogue.ControllerSeatName, strings.Join(behind, ", "))
+	}
 	bus, isNATS := server.Bus().(link.OverNATS)
 	if !isNATS {
 		return errors.New("the mesh's verbs are served over the bus, and this control plane is not on it")

cmd/mesh-controller/rollout.go

@@ -346,7 +346,9 @@ func rolloutMint(ctx context.Context, again bool) error {
 			}
 			machines++
 
-		case broker.KindModule:
+		case broker.KindModule, broker.KindNodeTools:
+			// The runtime is minted and delivered exactly as a module is (novox/hq ADR 0175): it is
+			// issued as the module it stands for, to that module's `broker` secret.
 			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
@@ -365,7 +367,7 @@ func rolloutMint(ctx context.Context, again bool) error {
 				skipped++
 				continue
 			}
-			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: inventory.BusModule, Node: p.Node, Module: p.Module})
+			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: busKindOf(p.Module), Node: p.Node, Module: p.Module})
 			if err != nil {
 				return err
 			}

cmd/mesh-controller/seatverbs.go

@@ -48,6 +48,21 @@ func argvFor(verb string, args map[string]any) ([]string, error) {
 		return nil
 	}
 	switch verb {
+	case "command":
+		// The generic verb: the command line as given, split as a shell would split it, with
+		// nothing added — the named verbs add flags a caller cannot reach; this one is the whole
+		// binary and says so in its description (novox/hq ADR 0154, 0175).
+		if err := need("command"); err != nil {
+			return nil, err
+		}
+		argv, err := splitCommandLine(str("command"))
+		if err != nil {
+			return nil, err
+		}
+		if len(argv) == 0 {
+			return nil, errors.New("command names no command")
+		}
+		return argv, nil
 	case "status":
 		return []string{"status", "--json"}, nil
 	case "nodes":
@@ -215,13 +230,15 @@ func runVerb(ctx context.Context, argv []string) (verbAnswer, error) {
 }
 
 // seatToolHandlers are the handlers for every verb the mesh-controller seat declares, from the
-// store's row, so a verb the row does not carry is not served and a verb it carries that this binary
-// cannot run is said at start rather than at the first call.
-func seatToolHandlers() (map[string]link.ToolHandler, error) {
+// store's row, so a verb the row does not carry is not served. A verb it carries that this binary
+// cannot run is named at start and answers the reason when called — never a refusal to serve, which
+// would take the whole control plane down for one word (novox/hq ADR 0185).
+func seatToolHandlers() (map[string]link.ToolHandler, []string, error) {
 	seat, known := catalogue.SeatNamed(catalogue.ControllerSeatName)
 	if !known {
-		return nil, fmt.Errorf("this mesh defines no %s seat", catalogue.ControllerSeatName)
+		return nil, nil, fmt.Errorf("this mesh defines no %s seat", catalogue.ControllerSeatName)
 	}
+	var behind []string
 	handlers := map[string]link.ToolHandler{}
 	for _, v := range seat.Serves {
 		verb := v.Name
@@ -232,8 +249,27 @@ func seatToolHandlers() (map[string]link.ToolHandler, error) {
 			continue
 		}
 		if _, err := argvFor(verb, sampleArguments(v)); err != nil {
-			return nil, fmt.Errorf("the %s seat's row declares %q, which this control plane cannot run: %w",
-				catalogue.ControllerSeatName, verb, err)
+			// **A row ahead of this binary is not a reason to go silent.**
+			//
+			// The row is the store's and a control plane follows it (novox/hq ADR 0154), so a verb
+			// this build does not know means the row was widened by a newer one — the ordinary
+			// state of a roll-out, and of a push that put an older control plane back. Refusing to
+			// serve at all made that transient fatal: on 2026-10-02 one unknown verb took the whole
+			// mesh off the bus for ten minutes, and the way back was a human running the binary by
+			// hand, because the thing that would have repaired it is the thing that was down
+			// (novox/hq 04-ISSUES/201, ADR 0185).
+			//
+			// So the verbs this binary knows are served, and this one answers the reason instead of
+			// nothing: a caller gets a sentence naming the fault, and everything else keeps working
+			// — including the push that replaces this binary with the one whose verb it is.
+			behind = append(behind, verb)
+			reason := err
+			handlers[verb] = func(context.Context, json.RawMessage) (any, error) {
+				return nil, fmt.Errorf("%s is in this mesh's %s row and the control plane running "+
+					"here cannot run it: %w. It is a verb of a newer build; this one is behind",
+					verb, catalogue.ControllerSeatName, reason)
+			}
+			continue
 		}
 		handlers[verb] = func(ctx context.Context, raw json.RawMessage) (any, error) {
 			args := map[string]any{}
@@ -249,7 +285,7 @@ func seatToolHandlers() (map[string]link.ToolHandler, error) {
 			return runVerb(ctx, argv)
 		}
 	}
-	return handlers, nil
+	return handlers, behind, nil
 }
 
 // seatTools is what `tools` answers: every seat with a protocol, and the tools each serves, from the
@@ -289,3 +325,57 @@ func sampleArguments(v catalogue.Verb) map[string]any {
 	}
 	return sample
 }
+
+// splitCommandLine splits a command line into words the way a POSIX shell does for the simple
+// cases a controller command needs: spaces separate, single or double quotes group, a backslash
+// escapes the next character inside double quotes or outside any. No expansion of anything.
+func splitCommandLine(line string) ([]string, error) {
+	var words []string
+	var cur strings.Builder
+	inWord := false
+	quote := rune(0)
+	runes := []rune(line)
+	for i := 0; i < len(runes); i++ {
+		r := runes[i]
+		switch {
+		case quote == '\'':
+			if r == '\'' {
+				quote = 0
+			} else {
+				cur.WriteRune(r)
+			}
+		case quote == '"':
+			if r == '"' {
+				quote = 0
+			} else if r == '\\' && i+1 < len(runes) {
+				i++
+				cur.WriteRune(runes[i])
+			} else {
+				cur.WriteRune(r)
+			}
+		case r == '\'' || r == '"':
+			quote = r
+			inWord = true
+		case r == '\\' && i+1 < len(runes):
+			i++
+			cur.WriteRune(runes[i])
+			inWord = true
+		case r == ' ' || r == '\t' || r == '\n':
+			if inWord {
+				words = append(words, cur.String())
+				cur.Reset()
+				inWord = false
+			}
+		default:
+			cur.WriteRune(r)
+			inWord = true
+		}
+	}
+	if quote != 0 {
+		return nil, fmt.Errorf("command has an unclosed %c quote", quote)
+	}
+	if inWord {
+		words = append(words, cur.String())
+	}
+	return words, nil
+}

cmd/mesh-controller/seatverbs_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"strings"
 	"testing"
 
@@ -130,10 +131,13 @@ func TestActsDoNotBlockTheCall(t *testing.T) {
 
 // What `tools` answers is the seats' records, with each verb's schema.
 func TestToolsAnswersTheSeatsRecords(t *testing.T) {
-	handlers, err := seatToolHandlers()
+	handlers, behind, err := seatToolHandlers()
 	if err != nil {
 		t.Fatal(err)
 	}
+	if len(behind) != 0 {
+		t.Fatalf("this build cannot run %v of its own seat's verbs", behind)
+	}
 	if len(handlers) != len(catalogue.ControllerVerbs) {
 		t.Fatalf("%d handlers for %d verbs", len(handlers), len(catalogue.ControllerVerbs))
 	}
@@ -171,3 +175,77 @@ func TestAJSONVerbsAnswerIsItsStandardOutput(t *testing.T) {
 		t.Fatalf("stderr and stdout are both what the command said: %s", answer.Output)
 	}
 }
+
+// `command` is the generic verb: the command line as given, split as a shell would, nothing added —
+// so an operator's `node account g14 jochen` is one call through the console rather than a shell on
+// the control node (novox/hq ADR 0154, ADR 0175).
+func TestCommandRunsTheLineAsGiven(t *testing.T) {
+	argv, err := argvFor("command", map[string]any{"command": "node account g14 jochen"})
+	if err != nil || strings.Join(argv, " ") != "node account g14 jochen" {
+		t.Fatalf("a plain line: %v %v", argv, err)
+	}
+	argv, err = argvFor("command", map[string]any{"command": `settings set dnsmasq '{"a": "b c"}' --node ace`})
+	if err != nil || len(argv) != 6 || argv[3] != `{"a": "b c"}` {
+		t.Fatalf("a quoted word stays one word: %q %v", argv, err)
+	}
+	argv, err = argvFor("command", map[string]any{"command": `node add "the box" --adopted`})
+	if err != nil || len(argv) != 4 || argv[2] != "the box" {
+		t.Fatalf("double quotes group: %q %v", argv, err)
+	}
+	if _, err := argvFor("command", map[string]any{"command": "   "}); err == nil {
+		t.Fatal("an empty line was accepted")
+	}
+	if _, err := argvFor("command", map[string]any{"command": `node "unclosed`}); err == nil {
+		t.Fatal("an unclosed quote was accepted")
+	}
+}
+
+// A verb in the row that this binary cannot run does not take the control plane off the bus: the
+// rest are served, the unknown one answers the reason, and the start-up names it (novox/hq ADR
+// 0185). One unknown word cost the mesh ten minutes of silence on 2026-10-02, recoverable only by
+// a person running the binary by hand — the push that would have repaired it needs the control
+// plane that was down.
+func TestARowAheadOfThisBuildIsServedAnyway(t *testing.T) {
+	seat, known := catalogue.SeatNamed(catalogue.ControllerSeatName)
+	if !known {
+		t.Fatal("no controller seat")
+	}
+	// The row as a newer control plane would have written it: every verb this build knows, and one
+	// it does not.
+	widened := seat
+	widened.Serves = append(append([]catalogue.Verb{}, seat.Serves...),
+		catalogue.Verb{Name: "teleport", Description: "a verb from a build that does not exist yet"})
+	rows := catalogue.DefaultSeats()
+	for i := range rows {
+		if rows[i].Name == catalogue.ControllerSeatName {
+			rows[i] = widened
+		}
+	}
+	catalogue.UseSeats(rows)
+	t.Cleanup(func() { catalogue.UseSeats(catalogue.DefaultSeats()) })
+
+	handlers, behind, err := seatToolHandlers()
+	if err != nil {
+		t.Fatalf("a row with one unknown verb refused to serve at all: %v", err)
+	}
+	if len(behind) != 1 || behind[0] != "teleport" {
+		t.Fatalf("the verbs this build cannot run were reported as %v", behind)
+	}
+	if len(handlers) != len(widened.Serves) {
+		t.Fatalf("%d handlers for %d verbs in the row", len(handlers), len(widened.Serves))
+	}
+	for _, known := range []string{"status", "nodes", "push"} {
+		if handlers[known] == nil {
+			t.Errorf("%s is not served although this build knows it", known)
+		}
+	}
+	_, err = handlers["teleport"](context.Background(), nil)
+	if err == nil {
+		t.Fatal("the unknown verb answered as though it had run")
+	}
+	for _, want := range []string{"teleport", "cannot run it", "behind"} {
+		if !strings.Contains(err.Error(), want) {
+			t.Errorf("the answer does not say %q: %v", want, err)
+		}
+	}
+}

examples/route-proxy/main.go

@@ -732,6 +732,11 @@ func handler(held *table) http.Handler {
 			// And since a host may now be routed only on some paths, those are a third thing:
 			// saying "no route for this name" while listing that very name as served is a
 			// contradiction an operator would have to disbelieve the proxy to get past.
+			// **Said in the log as well as to the client.** A name this mesh does not serve, asked
+			// for from outside, is what a scanner does, and the machine's intrusion prevention reads
+			// this proxy's log for exactly that line (novox/hq ADR 0179): the address last, as the
+			// jail's filter expects it.
+			log.Printf("refused: no route for %q, asked from %s", r.Host, r.RemoteAddr)
 			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 			w.WriteHeader(http.StatusNotFound)
 			if !hidden && held.routed(r.Host) {

internal/broker/agreement_catalogue_test.go

@@ -234,3 +234,13 @@ func admitsSubject(pattern, subject []string) bool {
 	}
 	return len(pattern) == len(subject)
 }
+
+// The two packages name the runtime module separately — the broker's types stay free of the
+// catalogue's on purpose — so this is what holds them to one string. A rename that reached only one
+// side would compose a runtime principal for a module nobody assigns, silently, and leave the one
+// that is assigned with a module's own grants.
+func TestTheBrokerAndTheCatalogueAgreeOnTheRuntimeModule(t *testing.T) {
+	if RuntimeModule != catalogue.RuntimeModule {
+		t.Fatalf("the broker calls the runtime %q and the catalogue %q", RuntimeModule, catalogue.RuntimeModule)
+	}
+}

internal/broker/derived.go

@@ -144,12 +144,18 @@ func ConsumerFor(p Principal) (Consumer, bool) {
 	}, true
 }
 
-// HolderConsumerFor is the worker a seat's holder gets on that seat's work queue.
+// HolderConsumerFor is the worker a seat's holders share 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.
+// **One worker for every holder, and each holder pulls one ask when it is idle** (novox/hq ADR
+// 0190). The seat is *authority* — who may be the telegram sender — and the worker is *delivery*,
+// kept separate so that relaxing one changes nothing about the other: a node-scoped seat has a
+// holder per machine, and all of them take from this one consumer, so the work is shared without
+// any holder knowing about the others. Pulled rather than pushed because a push consumer hands the
+// next ask to whichever subscriber the server picks, busy or not, and a pulled one is asked for by
+// a holder that has just become free. Which is also what ends the race issue 186 describes — asks
+// delivered behind the one being worked, expiring unacknowledged and dropped after the fifth
+// redelivery: nothing is delivered that nobody asked for. A long build keeps its own ask alive
+// (stillWorking); the ack wait is for a holder that died.
 func HolderConsumerFor(node, module string, seat DeclaredSeat) (Consumer, bool) {
 	if len(seat.Accepts) == 0 {
 		return Consumer{}, false
@@ -158,18 +164,13 @@ func HolderConsumerFor(node, module string, seat DeclaredSeat) (Consumer, bool)
 		Name:           "SEAT_" + upperSnake(seat.Name) + "_worker",
 		Stream:         seatStreamName(seat.Name),
 		Filters:        []string{"mesh.seat." + seat.Name + ".accept.>"},
-		Queue:          "holders",
 		AckWaitSeconds: 60,
 		MaxDeliver:     5,
-		// **One in flight.** A holder works one ask at a time, so the server hands it one at a
-		// time: with the default of many, every ask behind the one being worked was delivered,
-		// left unacknowledged for the length of the work, redelivered after the ack wait, and
-		// after the fifth time dropped — on 2026-10-01 twenty-six of forty-three builds asked in
-		// two minutes were never built, and the queue read as empty (novox/hq issue 186).
-		MaxAckPending: 1,
-		Why: fmt.Sprintf("%s on %s holds %s; it acknowledges after the work is done, so a "+
-			"crash mid-work redelivers rather than loses; one in flight, so a queue of asks is a "+
-			"queue and not a race against the ack wait", module, node, seat.Name),
+		// As many in flight as there are holders working, which pulling bounds by itself: a holder
+		// fetches one and fetches again only after it acknowledged. The server's default stands.
+		Why: fmt.Sprintf("%s on %s holds %s; every holder pulls one ask at a time from this worker "+
+			"and acknowledges after the work is done, so a crash mid-work redelivers rather than "+
+			"loses and an idle holder is the one that takes the next ask", module, node, seat.Name),
 	}, true
 }
 

internal/broker/derived_test.go

@@ -88,15 +88,20 @@ func TestAModuleThatConsumesNothingGetsNoConsumer(t *testing.T) {
 	}
 }
 
-// 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) {
+// The seat is authority and the worker is delivery (novox/hq ADR 0190): one worker per seat, shared
+// by every holder and pulled from, so a second holder takes the next ask rather than a copy of the
+// same one — which is what a queue group used to guard, and what pulling one durable gives outright.
+func TestAHoldersWorkerIsOneSharedByItsHolders(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")
+	two, _ := HolderConsumerFor("two", "telegram", telegramSeat())
+	if c.Name != two.Name || c.Stream != two.Stream {
+		t.Fatal("two holders got two workers, so each would process every ask")
+	}
+	if c.Push || c.Queue != "" {
+		t.Fatal("the worker is pushed, so the server would hand an ask to a busy holder")
 	}
 	if c.Stream != "SEAT_TELEGRAM_SENDER" {
 		t.Fatalf("the worker reads %q, not the seat's own stream", c.Stream)
@@ -154,15 +159,23 @@ func TestANodesDeclarationConsumerIsWhatItsOwnGrantAllows(t *testing.T) {
 	has(t, perms.Subscribe, c.Filters[0])
 }
 
-// A holder works one ask at a time, so the server hands it one at a time (novox/hq issue 186):
-// asks queued behind the one being worked wait in the stream rather than being delivered,
-// left to expire and dropped after the fifth redelivery.
-func TestAHoldersWorkerTakesOneAskAtATime(t *testing.T) {
-	c, found := HolderConsumerFor("anchor", "builder", DeclaredSeat{Name: "mesh-build-machine", Accepts: []string{"build"}})
+// Every holder of a seat shares one worker and pulls from it (novox/hq ADR 0190): no queue group
+// and no delivery subject, because a push consumer hands the next ask to whichever subscriber the
+// server picks, busy or not; and no cap of one in flight, because pulling bounds the asks in flight
+// by the holders that are free — which is what ended the race of issue 186, where asks delivered
+// behind the one being worked expired and were dropped.
+func TestAHoldersWorkerIsPulledByEveryHolder(t *testing.T) {
+	c, found := HolderConsumerFor("anchor", "build-agent", DeclaredSeat{Name: "node-build-agent", Accepts: []string{"build"}})
 	if !found {
 		t.Fatal("a seat that accepts work has no worker")
 	}
-	if c.MaxAckPending != 1 {
-		t.Fatalf("the worker may have %d asks in flight; one, so a queue is a queue", c.MaxAckPending)
+	if c.Queue != "" || c.Push {
+		t.Fatalf("the worker is pushed (queue %q, push %v); a holder pulls when it is free", c.Queue, c.Push)
+	}
+	if c.MaxAckPending != 0 {
+		t.Fatalf("the worker caps asks in flight at %d; pulling bounds them by the holders working", c.MaxAckPending)
+	}
+	if c.Name != "SEAT_NODE_BUILD_AGENT_worker" || c.Stream != "SEAT_NODE_BUILD_AGENT" {
+		t.Fatalf("the worker is %s on %s; one per seat, shared by its holders", c.Name, c.Stream)
 	}
 }

internal/broker/membership_test.go

@@ -73,3 +73,37 @@ func TestAnAccountMayReadItsOwnMembershipAndNoOthers(t *testing.T) {
 	has(t, perms.Publish, "$JS.API.DIRECT.GET.ASSIGNMENTS.mesh.assignment.anchor.postgres")
 	hasNot(t, perms.Subscribe, "mesh.assignment.>")
 }
+
+// The runtime arriving on a machine changes nothing about what each module is issued (to-be 38 WP2):
+// the memberships are composed as before and the runtime reads several of them. What the machine's
+// user list gains is one runtime principal, and loses nothing but the runtime module's own.
+func TestTheRuntimeArrivingLeavesEveryMembershipAsItWas(t *testing.T) {
+	filter := Seat{Name: "node-packet-filter", Scope: "node", Serves: []string{"rules", "reload"}}
+	three := []Declared{
+		{Module: "nftables", Holds: []Seat{filter}, Serves: []string{"firewall_rules"}},
+		{Module: "zsh", Serves: []string{"execute"}},
+		{Module: "systemd", Serves: []string{"units"}},
+	}
+	before := Records{Nodes: []string{"anchor"}, Assigned: map[string][]Declared{"anchor": three}}
+	after := Records{Nodes: []string{"anchor"}, Assigned: map[string][]Declared{
+		"anchor": append(append([]Declared{}, three...), Declared{Module: RuntimeModule}),
+	}}
+	for _, d := range three {
+		was := MembershipFor("anchor", d, PlacementsOf(before, nil))
+		is := MembershipFor("anchor", d, PlacementsOf(after, nil))
+		if !reflect.DeepEqual(was, is) {
+			t.Errorf("%s's membership changed when the runtime arrived:\n%+v\n%+v", d.Module, was, is)
+		}
+	}
+	users, err := Users(after)
+	if err != nil {
+		t.Fatal(err)
+	}
+	kinds := map[Kind]int{}
+	for _, p := range users {
+		kinds[p.Kind]++
+	}
+	if kinds[KindNodeTools] != 1 || kinds[KindModule] != 3 || kinds[KindNode] != 1 || kinds[KindController] != 1 {
+		t.Errorf("the machine's users are %v; one runtime, the three modules, the host and the controller", kinds)
+	}
+}

internal/broker/nats.go

@@ -34,8 +34,20 @@ const (
 	// 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"
+	// KindNodeTools is a machine's tool runtime (novox/hq ADR 0175, to-be 38): one process per
+	// node, on the host side, serving every assigned module's tools and every held seat's verbs.
+	// Its authority is the union of what the modules it carries would each have had for their
+	// tools — and nothing of what they consume, because tools are what it runs, not reactions.
+	KindNodeTools Kind = "node-tools"
 )
 
+// RuntimeModule is the module that IS the node's tool runtime (novox/hq ADR 0175). Where it is
+// assigned, the mesh composes one runtime principal for the machine in place of that module's own,
+// and the per-module containers that served tools until then stop being the way tools reach a node.
+// Mirrored in the catalogue package, which the agreement test holds to the same string; one
+// constant, so a rename is one edit and the two packages cannot drift.
+const RuntimeModule = "node-tools"
+
 // 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 {
@@ -74,6 +86,13 @@ type Principal struct {
 	// a namespace no such module owns. Every service started and the graph stayed empty.
 	Watches []Seat
 
+	// Carries are the modules whose tools this principal serves, for a KindNodeTools principal
+	// (novox/hq ADR 0175): every module assigned to its node, as each declares itself. Its
+	// serving authority is the union of theirs — each module's own tool namespace and each held
+	// seat's verbs on this node — derived from the same declarations the modules' own principals
+	// are, so the runtime can serve nothing a module could not have served for itself.
+	Carries []Declared
+
 	// Invokes are the tools this principal may call, as `<module>.<tool>`; a single `*` is every
 	// tool. A person's whole authority (design 25 §7), and a module's only if its manifest says so
 	// (novox/hq ADR 0152) — the console's does, and nothing else's.
@@ -91,10 +110,10 @@ type Principal struct {
 	PasswordHash string
 }
 
-// meshSeatsTheControllerUses are the roles the mesh's own flows submit work to. Named rather than
+// seatsTheControllerAsks 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"}
+var seatsTheControllerAsks = []string{"node-build-agent"}
 
 // 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.
@@ -112,7 +131,10 @@ func (p Principal) Username() string {
 	switch p.Kind {
 	case KindPerson:
 		return "person." + p.Module
-	case KindModule:
+	case KindModule, KindNodeTools:
+		// The runtime is named exactly as the module it stands for would have been: the mesh
+		// issues its credential through the same path a module's takes (`module issue`), and
+		// that path knows the node and the module, not the kind.
 		return p.Node + "." + p.Module
 	case KindNode:
 		return "node." + p.Node
@@ -186,7 +208,9 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		// 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 {
+		// A node-scoped seat's work subject carries no node (novox/hq ADR 0190): the ask goes to
+		// the role, and whichever machine holding it is idle takes it.
+		for _, seat := range seatsTheControllerAsks {
 			pub = append(pub, "mesh.seat."+seat+".accept.>")
 		}
 		// **And what the mesh says it did** (novox/hq ADR 0134). The control plane states its own
@@ -346,13 +370,17 @@ func PermissionsFor(p Principal) (Permissions, error) {
 
 		// 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).
+			// Taking work from the role's queue: the worker consumer every holder shares (asked
+			// about, pulled from, acknowledged), on the seat's own stream (novox/hq ADR 0190). A
+			// holder pulls — asks the consumer for its next message, answered on its own inbox —
+			// so what it needs is MSG.NEXT on that worker and nothing delivered to it. 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, "_DELIVER."+worker+".>")
-			pub = append(pub, "$JS.API.CONSUMER.INFO."+stream+"."+worker, "$JS.ACK."+stream+"."+worker+".>")
+			pub = append(pub,
+				"$JS.API.CONSUMER.INFO."+stream+"."+worker,
+				"$JS.API.CONSUMER.MSG.NEXT."+stream+"."+worker,
+				"$JS.ACK."+stream+"."+worker+".>")
 			for _, a := range s.Accepts {
 				sub = append(sub, seatSubject(s, "accept", a))
 			}
@@ -375,6 +403,48 @@ func PermissionsFor(p Principal) (Permissions, error) {
 				pub = append(pub, seatToolSubject(s, t, "*"))
 			}
 		}
+
+	case KindNodeTools:
+		// **One process serves what every module on the machine would have served for itself**
+		// (novox/hq ADR 0175). Each carried module's whole tool namespace — the same grant that
+		// module's own principal has, for the same reason: the tools a module serves are what its
+		// code answers, and a list here would be a second copy of it. Each held seat's verbs on
+		// this node, as the holder's own principal would be granted them.
+		for _, d := range p.Carries {
+			if !safeSubject.MatchString(d.Module) {
+				return Permissions{}, fmt.Errorf(
+					"%q cannot be part of a subject: a permission is a subject pattern, and this would widen it", d.Module)
+			}
+			own := "mesh.mod." + d.Module
+			sub = append(sub, own+".tool.>")
+			// A tool that emits an event is the module's code and emits under the module's name
+			// (ADR 0042); the runtime carrying that code may publish what the module declared it
+			// emits, and nothing it did not.
+			for _, e := range d.Emits {
+				pub = append(pub, own+".event."+e)
+			}
+			for _, s := range d.Holds {
+				for _, t := range s.Serves {
+					sub = append(sub, seatToolSubject(s, t, p.Node))
+				}
+			}
+		}
+		// Every assigned module's membership on this node (ADR 0160): one per module, read
+		// directly from the stream and followed live. This node's and no other's — the one token
+		// that varies is the module, so the pattern is the machine's own assignments.
+		sub = append(sub, "mesh.assignment."+p.Node+".*")
+		pub = append(pub, "$JS.API.DIRECT.GET."+AssignmentsStream+".mesh.assignment."+p.Node+".*")
+		// And every tool on the mesh (ADR 0175, decision 5): any node may call any tool on any
+		// node, as the console already could — the runtime is the console's serving mode.
+		invoked, err := invokedSubjects([]string{"*"})
+		if err != nil {
+			return Permissions{}, err
+		}
+		pub = append(pub, invoked...)
+		// Nothing about consumers: it consumes nothing. A module's reactions to events are its
+		// own long-lived process, which ADR 0175 leaves where it is; what moves here is tools.
+		sub = unique(sub)
+		pub = unique(pub)
 	}
 
 	if p.Kind == KindPerson {
@@ -382,6 +452,11 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		// consumer, because nothing is delivered to a person — they ask and are answered.
 		sub = append(sub, p.inbox())
 	}
+	if p.Kind == KindNodeTools {
+		// Its reply space, so the answers to what its tools call come back to it. No ack subject
+		// for the same reason a person has none: nothing is delivered to it.
+		sub = append(sub, p.inbox())
+	}
 
 	if p.Kind == KindModule || p.Kind == KindNode || p.Kind == KindController {
 		// Its own reply space, and nothing wider.
@@ -403,7 +478,7 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		// 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,
+		AllowResponses: p.Kind == KindModule || p.Kind == KindController || p.Kind == KindNodeTools,
 	}, nil
 }
 
@@ -625,6 +700,20 @@ func ComposeAccounts(principals []Principal) (string, error) {
 	return b.String(), nil
 }
 
+// unique is a sorted list with each subject once. Two carried modules holding seats with the same
+// verb, or the runtime module itself carried beside the others, would otherwise write a grant twice
+// — harmless to the server, and noise in a file that is read as the mesh's authority model.
+func unique(values []string) []string {
+	sort.Strings(values)
+	out := values[:0]
+	for i, v := range values {
+		if i == 0 || v != values[i-1] {
+			out = append(out, v)
+		}
+	}
+	return out
+}
+
 func quoted(values []string) string {
 	if len(values) == 0 {
 		return ""

internal/broker/nats_test.go

@@ -371,3 +371,94 @@ func TestAModulePullsItsOwnConsumerAndNoOthers(t *testing.T) {
 		}
 	}
 }
+
+// The runtime's authority is the union of what the modules it carries would have been granted for
+// their tools (novox/hq ADR 0175): every carried module's tool namespace, every held seat's verbs
+// on this node, every module's membership on this node, and a call to anything. Nothing it
+// consumes, because it reacts to nothing.
+func TestTheRuntimeServesTheUnionAndConsumesNothing(t *testing.T) {
+	filter := Seat{Name: "node-packet-filter", Scope: "node", Serves: []string{"rules", "reload"}}
+	p := Principal{Kind: KindNodeTools, Node: "anchor", Module: RuntimeModule, Carries: []Declared{
+		{Module: "nftables", Holds: []Seat{filter}, Serves: []string{"firewall_rules"}},
+		{Module: "zsh", Emits: []string{"shell.opened"}, Consumes: []string{"shop.order.placed"}},
+		{Module: RuntimeModule},
+	}}
+	perms, err := PermissionsFor(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{
+		"mesh.mod.nftables.tool.>", "mesh.mod.zsh.tool.>", "mesh.mod." + RuntimeModule + ".tool.>",
+		"mesh.seat.node-packet-filter.tool.rules.anchor", "mesh.seat.node-packet-filter.tool.reload.anchor",
+		"mesh.assignment.anchor.*",
+		"_INBOX.anchor." + RuntimeModule + ".>",
+	} {
+		if !contains(perms.Subscribe, want) {
+			t.Errorf("the runtime may not subscribe %s: %v", want, perms.Subscribe)
+		}
+	}
+	for _, want := range []string{
+		"mesh.mod.*.tool.>", "mesh.seat.*.tool.>",
+		"$JS.API.DIRECT.GET.ASSIGNMENTS.mesh.assignment.anchor.*",
+		"mesh.mod.zsh.event.shell.opened",
+	} {
+		if !contains(perms.Publish, want) {
+			t.Errorf("the runtime may not publish %s: %v", want, perms.Publish)
+		}
+	}
+	// Nothing of what a carried module consumes, and no consumer of its own to ack.
+	for _, s := range perms.Subscribe {
+		if strings.Contains(s, ".event.") || strings.HasPrefix(s, "_DELIVER.") {
+			t.Errorf("the runtime was granted a delivery it has no consumer for: %s", s)
+		}
+	}
+	for _, s := range perms.Publish {
+		if strings.HasPrefix(s, "$JS.ACK.") || strings.Contains(s, "CONSUMER") {
+			t.Errorf("the runtime was granted a consumer's subject and has no consumer: %s", s)
+		}
+	}
+	if !perms.AllowResponses {
+		t.Error("the runtime answers what it is asked, and may not reply")
+	}
+	if _, needed := ConsumerFor(p); needed {
+		t.Error("a consumer would be made for the runtime, which consumes nothing")
+	}
+	// Each subject once: the file is read as the mesh's authority model.
+	seen := map[string]bool{}
+	for _, s := range append(append([]string{}, perms.Subscribe...), perms.Publish...) {
+		if seen[s] {
+			t.Errorf("%s is granted twice", s)
+		}
+		seen[s] = true
+	}
+}
+
+func contains(list []string, want string) bool {
+	for _, s := range list {
+		if s == want {
+			return true
+		}
+	}
+	return false
+}
+
+// A node-scoped seat's work is shared (novox/hq ADR 0190): its holder on any machine subscribes the
+// seat's one work subject, with no node in it, so holders on several machines read one queue. The
+// node token belongs to a seat's tools, which are asked of one machine (design 33 §4), not to its work.
+func TestANodeSeatsWorkSubjectCarriesNoNode(t *testing.T) {
+	seat := Seat{Name: "node-build-agent", Scope: "node", Accepts: []string{"build"}, Serves: []string{"status"}}
+	perms, err := PermissionsFor(Principal{Kind: KindModule, Node: "anchor", Module: "build-agent", Holds: []Seat{seat}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	has(t, perms.Subscribe, "mesh.seat.node-build-agent.accept.build")
+	hasNot(t, perms.Subscribe, "mesh.seat.node-build-agent.accept.build.anchor")
+	// And its tools still carry the machine.
+	has(t, perms.Subscribe, "mesh.seat.node-build-agent.tool.status.anchor")
+	// The controller asks the role, not a machine.
+	controller, err := PermissionsFor(Principal{Kind: KindController})
+	if err != nil {
+		t.Fatal(err)
+	}
+	has(t, controller.Publish, "mesh.seat.node-build-agent.accept.>")
+}

internal/broker/streams.go

@@ -217,7 +217,7 @@ var ControllerFollows = []string{
 	// 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"),
+	seatEventSubject("node-build-agent", "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"),

internal/broker/testdata/composed.conf

@@ -24,8 +24,8 @@ accounts {
     jetstream: enabled
     users = [
       { user: "controller", password: "$2a$11$cccccccccccccccccccccc", permissions: {
-        publish: { allow: ["$JS.ACK.CONTROL.controller.>", "$JS.ACK.EVENTS.controller.>", "$JS.API.>", "_INBOX.enrol.>", "mesh.assignment.>", "mesh.control.>", "mesh.mod.*.tool.>", "mesh.node.>", "mesh.seat.mesh-build-machine.accept.>", "mesh.seat.mesh-controller.event.applied", "mesh.seat.mesh-controller.event.built-before", "mesh.seat.mesh-controller.event.refused"] }
-        subscribe: { allow: ["$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", "mesh.seat.mesh-controller.tool.>"] }
+        publish: { allow: ["$JS.ACK.CONTROL.controller.>", "$JS.ACK.EVENTS.controller.>", "$JS.API.>", "_INBOX.enrol.>", "mesh.assignment.>", "mesh.control.>", "mesh.mod.*.tool.>", "mesh.node.>", "mesh.seat.mesh-controller.event.applied", "mesh.seat.mesh-controller.event.built-before", "mesh.seat.mesh-controller.event.refused", "mesh.seat.node-build-agent.accept.>"] }
+        subscribe: { allow: ["$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-controller.tool.>", "mesh.seat.node-build-agent.event.built"] }
         allow_responses: { max: 1, ttl: "1m" }
       } }
       { user: "enrol.one", password: "$2a$11$eeeeeeeeeeeeeeeeeeeeee", permissions: {
@@ -37,8 +37,8 @@ accounts {
         subscribe: { allow: ["_DELIVER.one", "_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", "$JS.API.CONSUMER.MSG.NEXT.EVENTS.one_telegram", "$JS.API.DIRECT.GET.ASSIGNMENTS.mesh.assignment.one.telegram", "mesh.seat.telegram-sender.event.delivered", "mesh.seat.telegram-sender.event.failed"] }
-        subscribe: { allow: ["_DELIVER.SEAT_TELEGRAM_SENDER_worker", "_DELIVER.SEAT_TELEGRAM_SENDER_worker.>", "_INBOX.one.telegram.>", "mesh.assignment.one.telegram", "mesh.mod.telegram.tool.>", "mesh.seat.telegram-sender.accept.send"] }
+        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", "$JS.API.CONSUMER.MSG.NEXT.EVENTS.one_telegram", "$JS.API.CONSUMER.MSG.NEXT.SEAT_TELEGRAM_SENDER.SEAT_TELEGRAM_SENDER_worker", "$JS.API.DIRECT.GET.ASSIGNMENTS.mesh.assignment.one.telegram", "mesh.seat.telegram-sender.event.delivered", "mesh.seat.telegram-sender.event.failed"] }
+        subscribe: { allow: ["_INBOX.one.telegram.>", "mesh.assignment.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: {

internal/broker/users.go

@@ -62,13 +62,33 @@ func Users(r Records) ([]Principal, error) {
 
 	for _, node := range sortedCopy(r.Nodes) {
 		out = append(out, Principal{Kind: KindNode, Node: node})
+		// **Where the runtime is assigned, the machine gets one runtime principal in place of the
+		// runtime module's own** (novox/hq ADR 0175, to-be 38). It carries every module on the
+		// node: its serving grants are the union of theirs. Every other module keeps its own
+		// principal — a module still serving tools from its own container holds its own
+		// credential until it moves, and the two serve side by side in the meantime.
+		runtimeHere := false
 		for _, d := range r.Assigned[node] {
+			if d.Module == RuntimeModule {
+				runtimeHere = true
+			}
+		}
+		for _, d := range r.Assigned[node] {
+			if runtimeHere && d.Module == RuntimeModule {
+				continue
+			}
 			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, Invokes: d.Invokes,
 			})
 		}
+		if runtimeHere {
+			out = append(out, Principal{
+				Kind: KindNodeTools, Node: node, Module: RuntimeModule,
+				Carries: append([]Declared(nil), r.Assigned[node]...),
+			})
+		}
 	}
 	for _, node := range sortedCopy(r.Enrolling) {
 		out = append(out, Principal{Kind: KindEnrolment, Node: node})

internal/broker/users_test.go

@@ -245,3 +245,54 @@ func TestAUserListIsComposedBeforeAnythingMovesOntoTheBus(t *testing.T) {
 		t.Errorf("the composed list does not contain the machine running the bus")
 	}
 }
+
+// Where the runtime module is assigned, the machine gets one runtime principal in place of the
+// runtime module's own (novox/hq ADR 0175, to-be 38). Every other module keeps its own: a module
+// still serving tools from its own container holds its own credential until it moves.
+func TestTheRuntimeModuleBecomesTheMachinesRuntimePrincipal(t *testing.T) {
+	r := someRecords()
+	r.Assigned["one"] = append(r.Assigned["one"], Declared{Module: RuntimeModule})
+	users, err := Users(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var runtime *Principal
+	for i := range users {
+		p := &users[i]
+		if p.Node == "one" && p.Module == RuntimeModule {
+			if p.Kind == KindModule {
+				t.Fatalf("%s on one was composed as an ordinary module beside the runtime", RuntimeModule)
+			}
+			runtime = p
+		}
+	}
+	if runtime == nil || runtime.Kind != KindNodeTools {
+		t.Fatalf("one runs %s and got no runtime principal: %v", RuntimeModule, namesOf(t, r))
+	}
+	if runtime.Username() != "one."+RuntimeModule {
+		t.Errorf("the runtime is named %q; `module issue` names it as the module it stands for", runtime.Username())
+	}
+	carried := map[string]bool{}
+	for _, d := range runtime.Carries {
+		carried[d.Module] = true
+	}
+	if !carried["telegram"] || !carried[RuntimeModule] {
+		t.Errorf("the runtime carries %v; it carries every module on its node", carried)
+	}
+	// And the other node, where the runtime is not assigned, is exactly as before.
+	for _, p := range users {
+		if p.Node == "two" && p.Kind == KindNodeTools {
+			t.Fatal("two runs no runtime and was given a runtime principal")
+		}
+	}
+	// A module serving its own tools beside the runtime keeps its own principal.
+	found := false
+	for _, p := range users {
+		if p.Kind == KindModule && p.Node == "one" && p.Module == "telegram" {
+			found = true
+		}
+	}
+	if !found {
+		t.Error("telegram lost its own principal when the runtime arrived on its node")
+	}
+}

internal/builder/builder.go

@@ -968,6 +968,26 @@ func compile(ctx context.Context, run Runner, tree string, chain Toolchain,
 	if _, err := run(ctx, tree, "docker", invocation...); err != nil {
 		return "", err
 	}
+	if chain.Dependencies != "" {
+		// **What the bundle runs with, from the image it was compiled in** (Toolchain.Dependencies).
+		// A second run in the same image rather than a shell wrapped around the compiler: the
+		// compile line stays a plain command a reader can run by hand, and the copy is one more
+		// plain command beside it. Refused by name when the image carries no such directory — an
+		// older toolchain image — because a bundle packed without its dependencies starts nowhere
+		// and says so three layers away from here.
+		copying := []string{
+			"run", "--rm",
+			"--volume", tree + ":" + within,
+			"--workdir", within,
+			base,
+			"sh", "-c",
+			`test -d "$1" || { echo "the toolchain image carries no $1: it predates the mesh shipping a bundle's dependencies, rebuild $2 first" >&2; exit 1; }; cp -a "$1/." "$3/"`,
+			"dependencies", chain.Dependencies, chain.Base, out,
+		}
+		if _, err := run(ctx, tree, "docker", copying...); err != nil {
+			return "", fmt.Errorf("copying the %s dependencies a bundle runs with: %w", chain.Language, err)
+		}
+	}
 	return filepath.Join(tree, out), nil
 }
 

internal/builder/bundle_test.go

@@ -82,6 +82,41 @@ func TestABundleIsCompiledAndPackedWithNoDockerfile(t *testing.T) {
 	if !strings.HasPrefix(digest, "sha256:") {
 		t.Fatalf("the bundle was not pinned: %v", got.Manifest.Resources[0])
 	}
+
+	// **And what it runs with, from the image it was compiled in** (novox/hq to-be 38 WP3). A
+	// second run in the same toolchain image copies the toolchain's runtime directory — the
+	// `"type": "module"` package.json and the pruned node_modules — into the output's root, and
+	// refuses by name when the image carries none rather than packing a bundle that starts nowhere.
+	var copied string
+	for _, line := range r.ran {
+		if strings.HasPrefix(line, "docker run") && strings.Contains(line, "/app/runtime") {
+			copied = line
+		}
+	}
+	if copied == "" {
+		t.Fatalf("the bundle's dependencies were not copied in after the compile:\n%s", strings.Join(r.ran, "\n"))
+	}
+	if !strings.Contains(copied, "mesh-tools/build@sha256:") || !strings.Contains(copied, "predates") ||
+		!strings.Contains(copied, Out("code")) {
+		t.Fatalf("the copy does not run in the same toolchain, refuse an older image by name, or land in the artifact's output: %s", copied)
+	}
+	if strings.Index(strings.Join(r.ran, "\n"), "--outDir") > strings.Index(strings.Join(r.ran, "\n"), "/app/runtime") {
+		t.Fatal("the dependencies were copied before the compile wrote its output")
+	}
+}
+
+// A language whose bundle carries its own dependencies copies nothing in: a Go binary is static.
+func TestOnlyALanguageWithARuntimeDirectoryCopiesDependenciesIn(t *testing.T) {
+	ts, _ := ToolchainFor("typescript")
+	if ts.Dependencies != "/app/runtime" {
+		t.Fatalf("typescript bundles run with %q", ts.Dependencies)
+	}
+	for _, language := range []string{"go", "python"} {
+		chain, _ := ToolchainFor(language)
+		if chain.Dependencies != "" {
+			t.Fatalf("%s copies %q into every bundle, and its bundles carry their own", language, chain.Dependencies)
+		}
+	}
 }
 
 // **Refused before anything is built, naming what to build first.** A base the mesh has not built
@@ -145,9 +180,13 @@ func TestTwoBundlesInOneModuleArePackedSeparately(t *testing.T) {
 		t.Fatalf("a module with two bundles did not build: %v", err)
 	}
 
-	// Compiled into two different places.
+	// Compiled into two different places. Only the compile lines: the copy of each bundle's
+	// dependencies names the same directory again, deliberately.
 	var outputs []string
 	for _, line := range r.ran {
+		if !strings.Contains(line, "--outDir") {
+			continue
+		}
 		for _, part := range strings.Fields(line) {
 			if strings.HasPrefix(part, ".mesh-build/") {
 				outputs = append(outputs, part)

internal/builder/toolchain.go

@@ -57,6 +57,23 @@ type Toolchain struct {
 	// carrying its debug info. The mistake was believing a comment rather than reading the file it
 	// produced (novox/hq 04-ISSUES/161).
 	LinkerFlags []string
+	// Dependencies is a directory inside the toolchain image whose contents a bundle in this
+	// language runs with, copied whole into the compiled output's root after the compile.
+	//
+	// **A bundle that compiles is not yet a bundle that runs.** The compiler resolves `import
+	// "nats"` from the toolchain image's own node_modules and the pack takes only what the compiler
+	// wrote, so what a machine unpacked could not find a single dependency — and no TypeScript bundle
+	// had ever run live to show it (novox/hq to-be 38 WP3). For TypeScript the directory holds a
+	// `package.json` saying `"type": "module"` — Node reads a bare `.js` as CommonJS otherwise, so a
+	// bundle with its dependencies and without that line still fails to start — and the pruned,
+	// production-only node_modules the runtime itself ships with: the SDK's and the runtime's
+	// dependencies, and nothing module-specific yet (novox/hq ADR 0188 §5: a skeleton; a module's
+	// own npm dependencies are a later step). Empty for a language whose bundle carries its own —
+	// a Go binary is static, a Python bundle is installed with its dependencies.
+	//
+	// A toolchain image without the directory fails the build by name rather than packing a bundle
+	// that starts nowhere: the image predates this and must be rebuilt first.
+	Dependencies string
 	// SystemStamp is the variable this language's linker fills with the artifact's declared system,
 	// for a language whose binaries are pinned to one at link time (novox/hq ADR 0005).
 	//
@@ -107,14 +124,21 @@ var toolchains = []Toolchain{
 		// symlinks to a launcher that requires its library relatively — and the base image's own
 		// assembly resolves them away, leaving a launcher whose relative require points nowhere.
 		// Every module's hand-written Dockerfile had to know this. Now none of them does.
+		// **Rooted at the module, so an entrypoint lands where it is named.** Without a root the
+		// compiler takes the common directory of the files it is given: a module compiling only
+		// `tools/index.ts` had its output at `index.js`, and the entrypoint it declared —
+		// `tools/index.js`, "named as it will be found" — named a file the bundle did not
+		// contain. The runtime that loads bundles by their declared entrypoints (novox/hq ADR
+		// 0175) is what made this visible.
 		Compile: []string{
 			"node", "/app/node_modules/typescript/bin/tsc",
 			"--module", "NodeNext", "--moduleResolution", "NodeNext",
-			"--target", "ES2022",
+			"--target", "ES2022", "--rootDir", ".",
 		},
-		OutputFlag: "--outDir",
-		Unit:       UnitSources,
-		SourceExt:  ".ts",
+		OutputFlag:   "--outDir",
+		Unit:         UnitSources,
+		SourceExt:    ".ts",
+		Dependencies: "/app/runtime",
 	},
 	{
 		Language: "go",

internal/catalogue/build.go

@@ -67,6 +67,31 @@ func (m Manifest) Resolve(built []Built) (Manifest, error) {
 	out := m
 	out.Build = nil
 	out.Resources = nil
+	// What the build compiled, kept on the resolved manifest (novox/hq ADR 0175): a tools bundle is
+	// named by no resource of the module's own — the node's runtime loads it — so this is the only
+	// place the mesh would otherwise not have it. In artifact order, so two resolutions of one
+	// build compare equal.
+	out.Bundles = nil
+	if m.Build != nil {
+		for _, a := range m.Build.Artifacts {
+			if a.Kind != ArtifactBundle {
+				continue
+			}
+			made := by[a.Name]
+			// What the runtime loads: what the artifact said, else every entrypoint of a module
+			// that declares tools, else nothing (the field's own rule; see Artifact.Loads).
+			loads := append([]string(nil), a.Loads...)
+			if a.Loads == nil && len(m.Tools) > 0 {
+				loads = append([]string(nil), a.Entrypoints...)
+			}
+			out.Bundles = append(out.Bundles, Bundle{
+				Name: a.Name, Source: made.Reference, Digest: made.Digest,
+				Language: a.Language, Entrypoints: append([]string(nil), a.Entrypoints...),
+				Loads: loads,
+			})
+		}
+		sort.Slice(out.Bundles, func(i, j int) bool { return out.Bundles[i].Name < out.Bundles[j].Name })
+	}
 	for _, r := range m.Resources {
 		named, _ := r["artifact"].(string)
 		if named == "" {
@@ -191,6 +216,20 @@ 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))
 			}
+			// What the runtime loads is among what was compiled (ADR 0175): a name here that is
+			// not an entrypoint is a file the bundle does not contain, and the runtime would
+			// fail to import it on every machine rather than here.
+			for _, load := range a.Loads {
+				found := false
+				for _, e := range a.Entrypoints {
+					found = found || e == load
+				}
+				if !found {
+					problems = append(problems, fmt.Sprintf(
+						"%s: %q says the runtime loads %q, which is not among its entrypoints — "+
+							"what is loaded is compiled, so it is named there too", module, a.Name, load))
+				}
+			}
 			// **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

internal/catalogue/declaration.go

@@ -508,10 +508,27 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 				return nil, fmt.Errorf(
 					"%s needs a secret called %q and none was made for it", m.Module, name)
 			}
-			first = append(first, ownedBy(m.SecretsOwner, map[string]any{
+			// The runtime's credential belongs to the account the runtime runs as (novox/hq ADR 0175,
+			// to-be 38 WP3): its process is composed `user: <account>` where the node has one, and a
+			// root-owned 0600 file is one that process cannot read. Composed here rather than said in
+			// the manifest, because a manifest cannot say ${machine:account} safely — a node with no
+			// account has nothing to resolve it to, and then the runtime runs as root and the file
+			// stays root's.
+			owner := m.SecretsOwner
+			if m.Module == RuntimeModule && r.Account != "" {
+				owner = r.Account
+			}
+			first = append(first, ownedBy(owner, map[string]any{
 				"id": NeedID(name), "type": "file", "path": m.OwnSecrets[name].Path, "sealed": sealed,
 			}))
 		}
+		// This module's tools bundles, where the machine runs the node's tool runtime (novox/hq
+		// ADR 0175, to-be 38 WP2). Mesh-computed like everything above it, and before the module's
+		// own resources for the same reason: the runtime's process names the files inside these
+		// and is restarted when one changes, so they are on the machine before it is.
+		if r.runtimeHere() {
+			first = append(first, bundleArchives(m)...)
+		}
 		// Operator-owned paths this module is granted use of (novox/hq ADR 0051). Written before
 		// the module's own resources, and so before the container that mounts them: the host must
 		// find each present — refusing clearly if the operator has not provided it — before it
@@ -885,6 +902,17 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			out = append(out, fact)
 		}
 	}
+	// The node's tool runtime, last (novox/hq ADR 0175, to-be 38 WP2.3): one process loading every
+	// bundle delivered above and holding the credential sealed above, so both exist before it starts
+	// — the order written here is the order the machine applies.
+	if r.runtimeHere() {
+		process, err := r.runtimeProcess(with)
+		if err != nil {
+			return nil, err
+		}
+		owner[fmt.Sprint(process["id"])] = RuntimeModule
+		out = append(out, process)
+	}
 	if with.Adopted {
 		// First, before anything a module declares: what the mesh needs reachable, then its guard.
 		// The order a machine applies is the order written here.

internal/catalogue/machine_into_files.go

@@ -102,8 +102,11 @@ func accountHomeOf(account, home string) string {
 func machineInto(resource map[string]any, facts map[string]string, module string) error {
 	// 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"} {
+	// (novox/hq to-be 29), the same reason its content names ${machine:address}. And the name a
+	// `user` shape sets the login shell of, and the user a user-scoped unit or a process runs as:
+	// the shell module makes the operator's account its holder's login shell, and the desktop's
+	// watchers run as that account (novox/hq ADR 0176, ADR 0177) — neither can name the person.
+	for _, field := range []string{"path", "owner", "content", "name", "user"} {
 		s, ok := resource[field].(string)
 		if !ok {
 			continue

internal/catalogue/manifest.go

@@ -572,6 +572,36 @@ type Manifest struct {
 	// 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"`
+
+	// Bundles are this module's compiled bundles as the build produced them: what each is called,
+	// where it is, what it hashes to, what language it is in and which files a tool runtime loads
+	// from it (novox/hq ADR 0175, to-be 38).
+	//
+	// **Derived, never written.** The manifest in a repository says `build.artifacts`; the manifest
+	// the mesh holds says what came out, the way a resource naming an artifact comes to name a
+	// digest. Kept here because a tools bundle is referenced by no resource of the module's own —
+	// the node's runtime loads it, and the runtime is composed by the mesh — so without this the
+	// resolved manifest would carry no trace of the one artifact the runtime needs. A repository
+	// manifest that writes this beside a build is refused: it would be stating the build's output
+	// by hand.
+	Bundles []Bundle `json:"bundles,omitempty"`
+}
+
+// Bundle is one compiled bundle after it exists, as the resolved manifest carries it.
+type Bundle struct {
+	Name string `json:"name"`
+	// Source is where a machine fetches it, kept without the store's address like every reference
+	// the mesh records (artifacts.go); Digest is what it must hash to.
+	Source string `json:"source"`
+	Digest string `json:"digest"`
+	// Language is what it was compiled from, which is what says how it is run.
+	Language string `json:"language,omitempty"`
+	// Entrypoints are the compiled files it was built around, relative to its root.
+	Entrypoints []string `json:"entrypoints,omitempty"`
+	// Loads are the entrypoints a node's tool runtime imports from it: what the artifact said, or
+	// every entrypoint for a module declaring tools that said nothing. Empty for a bundle that is
+	// run rather than loaded.
+	Loads []string `json:"loads,omitempty"`
 }
 
 // Build says how to produce this module's artifacts from its source.
@@ -708,6 +738,16 @@ type Artifact struct {
 	// somebody adds a helper. An empty list is a bundle that is run rather than loaded — a
 	// provisioner or a step, named by whatever runs it.
 	Entrypoints []string `json:"entrypoints,omitempty"`
+
+	// Loads are the entrypoints of this bundle the node's tool runtime loads (novox/hq ADR 0175,
+	// to-be 38): the module's tool code, each file registering its tools as it is imported. A
+	// subset of Entrypoints, for a bundle that also carries things that are RUN — a daemon, a
+	// step, a report — and must not have them imported into the runtime.
+	//
+	// Absent means every entrypoint, for a module that declares `tools`: a bundle holding the
+	// module's tools and nothing else is the ordinary case and should not have to say the same
+	// list twice. A module declaring no tools has nothing the runtime loads, whatever it compiles.
+	Loads []string `json:"loads,omitempty"`
 }
 
 // Kinds an artifact may be.
@@ -1333,6 +1373,15 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	//
 	// Refused here because the alternative is a build that never returns, on a mesh new enough
 	// that nobody is watching it yet.
+	if m.Build != nil && len(m.Bundles) > 0 {
+		// The output of a build, written beside the build that produces it (ADR 0175). A resource
+		// naming a digest beside an `artifact` would be the same mistake, and is caught the same way:
+		// what the mesh derives, a repository does not state.
+		problems = append(problems, fmt.Sprintf(
+			"%s writes `bundles` beside its build. The mesh derives that from what the build "+
+				"produced; a manifest states `build.artifacts` and nothing about what came out",
+			m.Module))
+	}
 	if m.Build != nil && len(m.Build.Artifacts) > 0 {
 		for _, o := range m.Offers() {
 			if o != ArtifactStoreProvision {
@@ -1667,6 +1716,7 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	problems = append(problems, m.undeclaredMounts()...)
 	problems = append(problems, m.unknownDirRefs()...)
 	problems = append(problems, m.unknownAccessRefs()...)
+	problems = append(problems, m.jailProblems()...)
 
 	for i, r := range m.Resources {
 		id, _ := r["id"].(string)
@@ -1773,6 +1823,44 @@ var facilitiesOf = map[string][]string{
 	"virtualisation": {"/var/lib/incus/unix.socket"},
 }
 
+// jailProblems is every jail this module declares that the machine's intrusion prevention would
+// refuse (novox/hq ADR 0179).
+//
+// **Because one bad pattern stops every jail, not its own.** fail2ban expands `<HOST>` into a named
+// capture group, so a pattern naming it twice is a duplicate group name, and the daemon refuses the
+// whole configuration and exits — the machine keeps no bans at all, for any jail, including the one
+// watching its ssh. Caught live on the control node the day this was built, where a proxy's pattern
+// matched two shapes of refusal in one line. A pattern matches one shape; several shapes are several
+// patterns, one per line, as fail2ban's own filters are written.
+func (m Manifest) jailProblems() []string {
+	var problems []string
+	seen := map[string]bool{}
+	for _, j := range m.Jails {
+		switch {
+		case strings.TrimSpace(j.Name) == "":
+			problems = append(problems, m.Module+" declares a jail with no name")
+		case seen[j.Name]:
+			problems = append(problems, m.Module+" declares two jails called "+strconv.Quote(j.Name))
+		}
+		seen[j.Name] = true
+		if strings.TrimSpace(j.Failregex) == "" {
+			problems = append(problems, m.Module+"'s jail "+strconv.Quote(j.Name)+" says nothing a failed attempt looks like")
+		}
+		for _, line := range strings.Split(j.Failregex, "\n") {
+			if strings.TrimSpace(line) == "" {
+				continue
+			}
+			if n := strings.Count(line, "<HOST>"); n > 1 {
+				problems = append(problems, fmt.Sprintf("%s's jail %s names <HOST> %d times in one pattern; "+
+					"fail2ban reads it as one capture group and refuses the whole configuration, so the machine "+
+					"keeps no bans at all — write one pattern per shape, each naming <HOST> once",
+					m.Module, strconv.Quote(j.Name), n))
+			}
+		}
+	}
+	return problems
+}
+
 // undeclaredMounts is every bind-mount source no declaration covers — see the check above.
 func (m Manifest) undeclaredMounts() []string {
 	declared := map[string]bool{}

internal/catalogue/operators_machine_test.go

@@ -0,0 +1,60 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// A `user` shape and a user-scoped unit name the operator account the way a home file does
+// (novox/hq ADR 0176, ADR 0177): with ${machine:account}, resolved when the module is assigned.
+func TestAUserShapeAndAUserScopedUnitNameTheAccount(t *testing.T) {
+	facts := map[string]string{"account": "ops", "account-home": "/home/ops"}
+	login := map[string]any{"type": "user", "id": "login", "name": "${machine:account}", "shell": "/usr/bin/zsh"}
+	if err := machineInto(login, facts, "zsh"); err != nil {
+		t.Fatal(err)
+	}
+	if login["name"] != "ops" {
+		t.Fatalf("the user shape did not learn the account: %v", login["name"])
+	}
+	watcher := map[string]any{"type": "service", "id": "watcher", "unit": "i3-reload-watcher.service",
+		"scope": "user", "user": "${machine:account}"}
+	if err := machineInto(watcher, facts, "i3"); err != nil {
+		t.Fatal(err)
+	}
+	if watcher["user"] != "ops" {
+		t.Fatalf("the user-scoped unit did not learn the account: %v", watcher["user"])
+	}
+	// A machine with no operator account refuses rather than writing the literal.
+	err := machineInto(map[string]any{"type": "user", "id": "login", "name": "${machine:account}"},
+		map[string]string{"address": "10.0.0.1"}, "zsh")
+	if err == nil || !strings.Contains(err.Error(), "${machine:account}") {
+		t.Fatalf("a user shape on a machine with no account was not refused by name: %v", err)
+	}
+}
+
+// The service manager is a seat of the mesh's own with the unit verbs as its contract (novox/hq
+// ADR 0177): every verb described, with a schema, taking a scope.
+func TestTheServiceManagerSeatServesTheUnitVerbs(t *testing.T) {
+	seat, ok := SeatNamed("node-service-manager")
+	if !ok {
+		t.Fatal("node-service-manager is not a seat the mesh defines")
+	}
+	if seat.Scope != ScopeNode {
+		t.Fatalf("the service manager is a role each machine has once, and the seat is %s-scoped", seat.Scope)
+	}
+	want := []string{"units", "status", "start", "stop", "restart", "enable", "disable", "journal"}
+	var got []string
+	for _, v := range seat.Serves {
+		got = append(got, v.Name)
+		if v.Description == "" || v.Input == nil {
+			t.Fatalf("%s is promised without a description or a schema", v.Name)
+		}
+		props, _ := v.Input["properties"].(map[string]any)
+		if _, has := props["scope"]; !has {
+			t.Fatalf("%s takes no scope, and a user unit could not be asked for", v.Name)
+		}
+	}
+	if strings.Join(got, ",") != strings.Join(want, ",") {
+		t.Fatalf("the seat serves %v, not %v", got, want)
+	}
+}

internal/catalogue/runtime.go

@@ -0,0 +1,251 @@
+package catalogue
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// The node's tool runtime, as the catalogue knows it (novox/hq ADR 0175, to-be 38).
+//
+// **One module is the runtime.** Where it is assigned, one process per machine serves every assigned
+// module's tools and every held seat's verbs, on the host side, from the bundles each module's build
+// produced — and no module needs a container to reach the bus with its tools. The name is a constant
+// rather than a manifest field because a rule turns on it: the composer places the runtime's process
+// where this module is, and registration refuses the old pattern once this module exists.
+
+// RuntimeModule is the module that is the node's tool runtime. Mirrored in the broker package,
+// which composes a principal of its own for it; the agreement test there holds the two to one string.
+const RuntimeModule = "node-tools"
+
+// BundleRoot is where a machine keeps the tools bundles the mesh delivers to it: under the mesh's
+// own directory, beside the daemons the host unpacks there, and never where a package manager also
+// writes. One directory per module, one per bundle beneath it, at a path that does not move with
+// the version — so the runtime's process names each entrypoint once and is restarted, not
+// recomposed, when a bundle changes.
+const BundleRoot = "/var/lib/mesh/bundles"
+
+// BundleID names the archive resource that delivers one of a module's bundles; prefixed with the
+// module like every resource of its own.
+func BundleID(bundle string) string { return "bundle-" + bundle }
+
+// BundlePath is where one module's bundle is unpacked on a machine.
+func BundlePath(module, bundle string) string { return BundleRoot + "/" + module + "/" + bundle }
+
+// runtimeHere says whether this node's set includes the runtime module, which is what decides
+// whether anything about tools changes on the machine (to-be 38 WP2): until the runtime is assigned,
+// a node is sent exactly what it was sent before, bundles included, because a bundle nothing loads
+// is bytes nobody reads.
+func (r Resolution) runtimeHere() bool {
+	for _, m := range r.Modules {
+		if m.Module == RuntimeModule {
+			return true
+		}
+	}
+	return false
+}
+
+// bundleArchives is one archive per tools bundle of a module — a bundle the runtime LOADS something
+// from — as the host fetches and unpacks any artifact (novox/hq ADR 0175 §3: a module brings its
+// tools as a bundle, delivered by the host like any artifact, never an image). A bundle it loads
+// nothing from is run rather than loaded: a daemon, a step, the runtime itself — delivered by the
+// process that runs it, and not again here.
+//
+// The source is the kept reference; the per-resource pass that follows routes it through the
+// artifact store as this network reaches it now, as it does every image and archive the mesh built.
+func bundleArchives(m Manifest) []map[string]any {
+	var out []map[string]any
+	for _, b := range m.Bundles {
+		if len(b.Loads) == 0 {
+			continue
+		}
+		out = append(out, map[string]any{
+			"id": BundleID(b.Name), "type": "archive",
+			"source": b.Source, "digest": b.Digest,
+			"path": BundlePath(m.Module, b.Name),
+		})
+	}
+	return out
+}
+
+// RuntimeProcessID names the one process the mesh composes for a machine's runtime; prefixed with
+// the runtime module like a resource of its own, because that module is what the host sees it as.
+func RuntimeProcessID() string { return "runtime" }
+
+// RuntimeToolModules is the variable the runtime reads the modules it serves from: one
+// `<module>=<entrypoint>` per file it loads, comma-separated — several entries may name one module.
+// RuntimeBrokerFile is where it reads the node's credential; RuntimeOperatorAccount and
+// RuntimeOperatorHome are the machine's operator account and home, handed to every tool's
+// environment (to-be 38 WP1), and absent on a machine with no account.
+const (
+	RuntimeToolModules     = "MESH_TOOL_MODULES"
+	RuntimeBrokerFile      = "MESH_BROKER_FILE"
+	RuntimeOperatorAccount = "MESH_OPERATOR_ACCOUNT"
+	RuntimeOperatorHome    = "MESH_OPERATOR_HOME"
+)
+
+// interpreterFor is how a bundle in a language is run: the program the host's unit starts, with the
+// bundle's entrypoint after it. The one thing the composer takes from a language, and said here
+// rather than in a manifest because the runtime's process is the mesh's to compose (to-be 38 WP3).
+func interpreterFor(language string) (string, error) {
+	switch language {
+	case "typescript":
+		return "node", nil
+	}
+	return "", fmt.Errorf(
+		"%s is written in %q, and the mesh knows no interpreter to run a %q bundle with",
+		RuntimeModule, language, language)
+}
+
+// runtimeProcess is the one process a machine runs the node's tool runtime as (novox/hq ADR 0175,
+// to-be 38 WP2.3): the runtime module's own bundle, run by its language's interpreter, told which
+// modules it serves and from which files, where its credential is, and who the machine's operator
+// is — and restarted when any bundle it loads or the credential it holds changes.
+//
+// Composed from the placed manifests, so the credential's path is where this node puts it. The
+// runtime runs as the operator's account when the machine has one, which is what lets a tool that
+// needs root escalate as the operator would (ADR 0175 §4); on a machine with no account it runs as
+// root, and the two operator words are not set.
+func (r Resolution) runtimeProcess(with Rendering) (map[string]any, error) {
+	var runtime *Manifest
+	for i := range r.Modules {
+		if r.Modules[i].Module == RuntimeModule {
+			runtime = &r.Modules[i]
+		}
+	}
+	if runtime == nil {
+		return nil, nil
+	}
+	if len(runtime.Bundles) != 1 {
+		return nil, fmt.Errorf(
+			"%s is assigned to %s and its build produced %d bundle(s); the runtime is one bundle "+
+				"the mesh runs, so the module declares exactly one (novox/hq to-be 38)",
+			RuntimeModule, r.Node, len(runtime.Bundles))
+	}
+	bundle := runtime.Bundles[0]
+	if len(bundle.Entrypoints) != 1 {
+		return nil, fmt.Errorf(
+			"%s's bundle %q names %d entrypoint(s); the runtime is run from one, so the module "+
+				"declares exactly one (novox/hq to-be 38)", RuntimeModule, bundle.Name, len(bundle.Entrypoints))
+	}
+	interpreter, err := interpreterFor(bundle.Language)
+	if err != nil {
+		return nil, err
+	}
+	credential, declared := runtime.OwnSecrets["broker"]
+	if !declared {
+		return nil, fmt.Errorf(
+			"%s declares no own secret named broker, and the node's credential is delivered there: "+
+				"a module that speaks on the bus declares \"own-secrets\": {\"broker\": <path>}",
+			RuntimeModule)
+	}
+
+	// What it serves, and from which files: every module on this machine that composes here, in
+	// name order, each bundle it loads from in the order the manifest gave. A module left out of
+	// the declaration — a filter on an adopted machine — is left out of this too, or the runtime
+	// would be told to load files that were never delivered.
+	var served []string
+	var restartOn []string
+	for _, m := range r.Modules {
+		if with.Adopted && m.Filtering != nil {
+			continue
+		}
+		for _, b := range m.Bundles {
+			if len(b.Loads) == 0 {
+				continue
+			}
+			for _, load := range b.Loads {
+				served = append(served, m.Module+"="+BundlePath(m.Module, b.Name)+"/"+load)
+			}
+			restartOn = append(restartOn, m.Module+"."+BundleID(b.Name))
+		}
+	}
+	sort.Strings(served)
+	restartOn = append(restartOn, RuntimeModule+"."+NeedID("broker"))
+	sort.Strings(restartOn)
+
+	env := map[string]string{
+		RuntimeToolModules: strings.Join(served, ","),
+		RuntimeBrokerFile:  credential.Path,
+	}
+	process := map[string]any{
+		"id": RuntimeModule + "." + RuntimeProcessID(), "type": "process", "name": RuntimeModule,
+		"source": bundle.Source, "digest": bundle.Digest,
+		"run":        []any{interpreter, bundle.Entrypoints[0]},
+		"env":        env,
+		"restart-on": toAny(restartOn),
+	}
+	if r.Account != "" {
+		env[RuntimeOperatorAccount] = r.Account
+		env[RuntimeOperatorHome] = accountHomeOf(r.Account, r.AccountHome)
+		process["user"] = r.Account
+	}
+	// Routed through the artifact store as this network reaches it now, like everything the mesh
+	// built; refused with the same words when there is no store to route through.
+	if err := artifactsInto(process, RuntimeModule, with); err != nil {
+		return nil, err
+	}
+	return process, nil
+}
+
+func toAny(in []string) []any {
+	out := make([]any, 0, len(in))
+	for _, s := range in {
+		out = append(out, s)
+	}
+	return out
+}
+
+// RuntimeImageModule and RuntimeImageArtifact name the image every per-module tool container was
+// built on: the tool runtime's own runtime image. With the runtime a module of its own, that image
+// stays the way a module's SERVICE may be built and stops being the way tools reach a node (ADR 0175).
+const (
+	RuntimeImageModule   = "mesh-tools"
+	RuntimeImageArtifact = "runtime"
+)
+
+// ToolContainerOnTheRuntime says why a manifest is the pattern ADR 0175 retires — a module whose tools
+// are served from a container built on the tool runtime's image — or nothing when it is not. Judged
+// from the manifest's own `build.on` when it is a repository manifest, and from what its build stood
+// on when it is a built one, because a resolved manifest carries no build. The gate itself is
+// registration's (to-be 38 WP2.4): once the runtime module is in the catalogue, this is refused.
+//
+// Three things must hold, and each alone is fine: declaring tools (a bundle does that); a container
+// (a module's service may well be one); building on the runtime's image (a service written against
+// the SDK may). All three is a container whose purpose is tools, which the runtime now serves.
+func ToolContainerOnTheRuntime(m Manifest, against []string) string {
+	if len(m.Tools) == 0 {
+		return ""
+	}
+	container := false
+	for _, r := range m.Resources {
+		if fmt.Sprint(r["type"]) == "container" {
+			container = true
+		}
+	}
+	if !container {
+		return ""
+	}
+	onTheRuntime := false
+	if m.Build != nil {
+		for _, on := range m.Build.On {
+			if on.Module == RuntimeImageModule && on.Artifact == RuntimeImageArtifact {
+				onTheRuntime = true
+			}
+		}
+	}
+	for _, ref := range against {
+		path, kept := InArtifactStore(Recorded(ref))
+		if kept && strings.HasPrefix(path, RuntimeImageModule+"/"+RuntimeImageArtifact+"@") {
+			onTheRuntime = true
+		}
+	}
+	if !onTheRuntime {
+		return ""
+	}
+	return fmt.Sprintf(
+		"%s declares tools and a container built on %s's %s image — a container whose purpose is "+
+			"serving tools. The node's tool runtime (%s) serves every module's tools from its bundle "+
+			"now (novox/hq ADR 0175, to-be 38); declare the tools as a bundle and drop the container",
+		m.Module, RuntimeImageModule, RuntimeImageArtifact, RuntimeModule)
+}

internal/catalogue/runtime_gate_test.go

@@ -0,0 +1,88 @@
+package catalogue
+
+import (
+	"strings"
+	"testing"
+)
+
+// The packet-filter manifest as it was the day the runtime was decided (novox/hq ADR 0175): tools,
+// served from a container built on the tool runtime's image, with NET_ADMIN so the container could
+// reach the filter. The exact pattern to-be 38 WP4 moves it off, and the one the gate refuses.
+const thePacketFilterAsItWas = `{
+  "module": "nftables",
+  "version": "1",
+  "capabilities": ["firewall", "container-runtime"],
+  "claims": [{"name": "node-packet-filter", "scope": "node", "serves": ["rules", "reload", "remove"]}],
+  "filtering": {"into": "/etc/nftables.conf"},
+  "resources": [
+    {"id": "mesh-state", "type": "directory", "mode": "0700", "place": "mesh"},
+    {"id": "package", "type": "package", "package": "nftables"},
+    {"id": "unit", "type": "file", "path": "/etc/systemd/system/mesh-filter.service",
+     "content": "[Unit]\nDescription=The mesh's packet filter\n[Service]\nType=oneshot\nExecStart=nft -f /etc/nftables.conf\n", "mode": "0644"},
+    {"id": "load", "type": "service", "unit": "mesh-filter.service", "state": "running", "boot": "enabled",
+     "restart-on": ["unit"], "reload-on": ["filtering"]},
+    {"id": "runtime", "type": "container", "name": "mesh-nftables", "network": "host",
+     "capabilities": ["NET_ADMIN"],
+     "volumes": ["${dir:mesh-state}/broker:/run/secrets/broker:ro", "/etc/nftables.conf:/etc/nftables.conf:ro"],
+     "env": {"MESH_BROKER_FILE": "/run/secrets/broker", "MESH_FILTER_FILE": "/etc/nftables.conf"},
+     "artifact": "runtime"}
+  ],
+  "tools": ["firewall_rules"],
+  "own-secrets": {"broker": "${dir:mesh-state}/broker"},
+  "build": {
+    "on": [
+      {"arg": "BUILD_BASE", "module": "mesh-tools", "artifact": "build"},
+      {"arg": "RUNTIME_BASE", "module": "mesh-tools", "artifact": "runtime"}
+    ],
+    "artifacts": [{"name": "runtime", "kind": "image", "from": "Dockerfile"}]
+  }
+}`
+
+func TestAToolContainerOnTheRuntimeImageIsNamedForWhatItIs(t *testing.T) {
+	m, err := ParseManifest([]byte(thePacketFilterAsItWas))
+	if err != nil {
+		t.Fatal(err)
+	}
+	// From the repository: the manifest says what it builds on.
+	why := ToolContainerOnTheRuntime(m, nil)
+	if why == "" {
+		t.Fatal("the packet filter's tool container was not recognised from its build")
+	}
+	for _, word := range []string{"nftables", "mesh-tools", "runtime", "ADR 0175", "bundle"} {
+		if !strings.Contains(why, word) {
+			t.Errorf("the refusal does not say %q: %s", word, why)
+		}
+	}
+
+	// Built: the manifest carries no build, and what it stood on says the same.
+	built, err := m.Resolve([]Built{{Name: "runtime", Kind: ArtifactImage,
+		Reference: ArtifactStoreScheme + "nftables/runtime@" + digest}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	stoodOn := []string{"anchor.internal:5100/mesh-tools/build@" + digest, "anchor.internal:5100/mesh-tools/runtime@" + digest}
+	if ToolContainerOnTheRuntime(built, stoodOn) == "" {
+		t.Error("the packet filter's tool container was not recognised from what its build stood on")
+	}
+	if ToolContainerOnTheRuntime(built, nil) != "" {
+		t.Error("a built manifest with no record of its base was judged to be on the runtime")
+	}
+
+	// Each of the three alone is an ordinary module.
+	bundle := m
+	bundle.Resources = m.Resources[:len(m.Resources)-1]
+	if ToolContainerOnTheRuntime(bundle, nil) != "" {
+		t.Error("a module with tools and no container is the pattern the runtime serves, and was refused")
+	}
+	service := m
+	service.Tools = nil
+	if ToolContainerOnTheRuntime(service, nil) != "" {
+		t.Error("a service built against the SDK, declaring no tools, was refused")
+	}
+	elsewhere := m
+	elsewhere.Build = &Build{On: []BuildsOn{{Arg: "NODE_BASE", Image: "node@" + digest}},
+		Artifacts: m.Build.Artifacts}
+	if ToolContainerOnTheRuntime(elsewhere, nil) != "" {
+		t.Error("a tool container on a public base was refused as though it were on the runtime's")
+	}
+}

internal/catalogue/runtime_test.go

@@ -0,0 +1,212 @@
+package catalogue
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+)
+
+// The node's tool runtime (novox/hq ADR 0175, to-be 38): where the runtime module is assigned, a
+// machine is sent every assigned module's tools bundle as an archive, and the runtime's own process
+// loading them. Where it is not, the machine is sent exactly what it was sent before.
+
+var bundleDigest = "sha256:" + strings.Repeat("b", 64)
+
+// aToolsModule is a module whose tools come as a compiled bundle and nothing else — the shape every
+// module takes once its tool container goes (to-be 38 WP4).
+func aToolsModule(t *testing.T, name string, entrypoints ...string) Manifest {
+	t.Helper()
+	m := Manifest{Module: name, Version: "1", Tools: []string{"status"},
+		Build: &Build{Artifacts: []Artifact{
+			{Name: "tools", Kind: ArtifactBundle, Language: "typescript", Entrypoints: entrypoints},
+		}}}
+	resolved, err := m.Resolve([]Built{{Name: "tools", Kind: ArtifactBundle,
+		Reference: ArtifactStoreScheme + name + "/tools/blobs/" + bundleDigest, Digest: bundleDigest}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return resolved
+}
+
+// theRuntime is the runtime module as the catalogue holds it: its own bundle, run rather than
+// loaded, and its broker secret to receive the node's credential in.
+func theRuntime(t *testing.T) Manifest {
+	t.Helper()
+	m := Manifest{Module: RuntimeModule, Version: "1",
+		OwnSecrets: OwnSecrets{"broker": {Path: "/var/lib/mesh/" + RuntimeModule + "/broker"}},
+		Build: &Build{Artifacts: []Artifact{{Name: "runtime", Kind: ArtifactBundle, Language: "typescript",
+			Entrypoints: []string{"src/main.js"}}}}}
+	resolved, err := m.Resolve([]Built{{Name: "runtime", Kind: ArtifactBundle,
+		Reference: ArtifactStoreScheme + RuntimeModule + "/runtime/blobs/" + bundleDigest, Digest: bundleDigest}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return resolved
+}
+
+func TestABuildsBundlesAreCarriedOnTheResolvedManifest(t *testing.T) {
+	m := aToolsModule(t, "nftables", "tools/index.js")
+	if len(m.Bundles) != 1 {
+		t.Fatalf("the resolved manifest carries %d bundle(s), not the one the build made", len(m.Bundles))
+	}
+	b := m.Bundles[0]
+	if b.Name != "tools" || b.Digest != bundleDigest || b.Language != "typescript" ||
+		b.Source != ArtifactStoreScheme+"nftables/tools/blobs/"+bundleDigest ||
+		len(b.Entrypoints) != 1 || b.Entrypoints[0] != "tools/index.js" {
+		t.Errorf("the bundle is carried as %+v", b)
+	}
+	// A repository manifest may not write what the build derives.
+	raw := `{"module":"x","version":"1","build":{"artifacts":[{"name":"t","kind":"bundle","language":"typescript"}]},` +
+		`"bundles":[{"name":"t","source":"s","digest":"` + bundleDigest + `"}]}`
+	if _, err := ParseManifest([]byte(raw)); err == nil || !strings.Contains(err.Error(), "bundles") {
+		t.Errorf("a manifest stating its build's output by hand was accepted: %v", err)
+	}
+}
+
+func TestEveryToolsBundleIsDeliveredWhereTheRuntimeRuns(t *testing.T) {
+	store := Rendering{ArtifactStore: "anchor.internal:5101",
+		Needed: map[string]map[string]string{RuntimeModule: {"broker": "sealed-credential"}}}
+	nftables := aToolsModule(t, "nftables", "tools/index.js")
+	zsh := aToolsModule(t, "zsh", "tools/index.js", "tools/more.js")
+
+	t.Run("with the runtime, one archive per tools bundle", func(t *testing.T) {
+		r := Resolution{Node: "anchor", Modules: []Manifest{nftables, zsh, theRuntime(t)}}
+		out, err := r.Declaration(store)
+		if err != nil {
+			t.Fatal(err)
+		}
+		archive := fileNamed(out, "nftables."+BundleID("tools"))
+		if archive == nil {
+			t.Fatalf("nftables' tools bundle was not delivered: %v", ids(out))
+		}
+		if archive["type"] != "archive" || archive["digest"] != bundleDigest ||
+			archive["path"] != BundleRoot+"/nftables/tools" {
+			t.Errorf("delivered as %v", archive)
+		}
+		if archive["source"] != "http://anchor.internal:5101/v2/nftables/tools/blobs/"+bundleDigest {
+			t.Errorf("fetched from %v, not through the store as this network reaches it", archive["source"])
+		}
+		if fileNamed(out, "zsh."+BundleID("tools")) == nil {
+			t.Errorf("zsh's tools bundle was not delivered: %v", ids(out))
+		}
+		// The runtime's own bundle is run, not loaded: its process delivers it, not an archive.
+		if fileNamed(out, RuntimeModule+"."+BundleID("runtime")) != nil {
+			t.Error("the runtime's own bundle was delivered as an archive beside its process")
+		}
+	})
+
+	t.Run("without the runtime, nothing changes", func(t *testing.T) {
+		r := Resolution{Node: "anchor", Modules: []Manifest{nftables, zsh}}
+		out, err := r.Declaration(store)
+		if err != nil {
+			t.Fatal(err)
+		}
+		for _, id := range ids(out) {
+			if strings.Contains(id, BundleID("")) {
+				t.Errorf("%s was delivered to a machine running no runtime to load it", id)
+			}
+		}
+	})
+}
+
+func ids(out []map[string]any) []string {
+	var names []string
+	for _, r := range out {
+		names = append(names, r["id"].(string))
+	}
+	return names
+}
+
+// One process per machine runs the runtime from its own bundle, told what it serves and from where,
+// where its credential is, and who the operator is — restarted when any of that changes.
+func TestTheMachineRunsOneRuntimeLoadingEveryDeliveredBundle(t *testing.T) {
+	with := Rendering{ArtifactStore: "anchor.internal:5101",
+		Needed: map[string]map[string]string{RuntimeModule: {"broker": "sealed-credential"}}}
+	nftables := aToolsModule(t, "nftables", "tools/index.js")
+	// A bundle carrying a daemon beside its tools says which files the runtime loads.
+	showcase := Manifest{Module: "showcase", Version: "1", Tools: []string{"greet"},
+		Build: &Build{Artifacts: []Artifact{{Name: "code", Kind: ArtifactBundle, Language: "typescript",
+			Entrypoints: []string{"daemon/index.js", "tools/index.js"}, Loads: []string{"tools/index.js"}}}}}
+	showcase, err := showcase.Resolve([]Built{{Name: "code", Kind: ArtifactBundle,
+		Reference: ArtifactStoreScheme + "showcase/code/blobs/" + bundleDigest, Digest: bundleDigest}})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r := Resolution{Node: "anchor", Account: "ops", Modules: []Manifest{nftables, showcase, theRuntime(t)}}
+	out, err := r.Declaration(with)
+	if err != nil {
+		t.Fatal(err)
+	}
+	process := fileNamed(out, RuntimeModule+"."+RuntimeProcessID())
+	if process == nil {
+		t.Fatalf("no runtime process was composed: %v", ids(out))
+	}
+	if process["type"] != "process" || process["name"] != RuntimeModule || process["digest"] != bundleDigest ||
+		process["source"] != "http://anchor.internal:5101/v2/"+RuntimeModule+"/runtime/blobs/"+bundleDigest {
+		t.Errorf("the runtime's process is %v", process)
+	}
+	if fmt.Sprint(process["run"]) != "[node src/main.js]" {
+		t.Errorf("the runtime is run as %v; its bundle's one entrypoint, by its language's interpreter", process["run"])
+	}
+	env := process["env"].(map[string]string)
+	if env[RuntimeToolModules] != "nftables="+BundleRoot+"/nftables/tools/tools/index.js,"+
+		"showcase="+BundleRoot+"/showcase/code/tools/index.js" {
+		t.Errorf("the runtime is told to serve %q: every loaded file, by module, and nothing a bundle runs", env[RuntimeToolModules])
+	}
+	if env[RuntimeBrokerFile] != "/var/lib/mesh/"+RuntimeModule+"/broker" {
+		t.Errorf("the runtime reads its credential at %q, not where the module's own secret is placed", env[RuntimeBrokerFile])
+	}
+	if env[RuntimeOperatorAccount] != "ops" || env[RuntimeOperatorHome] != "/home/ops" || process["user"] != "ops" {
+		t.Errorf("the operator is not handed to the runtime: %v as %v", env, process["user"])
+	}
+	// The credential the process reads belongs to the account it runs as, or it could not read it
+	// (to-be 38 WP3); other modules' secrets are left as their manifests say.
+	if credential := fileNamed(out, RuntimeModule+"."+NeedID("broker")); credential == nil || credential["owner"] != "ops" {
+		t.Errorf("the runtime's credential is not the account's to read: %v", credential)
+	}
+	restarts := fmt.Sprint(process["restart-on"])
+	for _, want := range []string{"nftables." + BundleID("tools"), "showcase." + BundleID("code"), RuntimeModule + "." + NeedID("broker")} {
+		if !strings.Contains(restarts, want) {
+			t.Errorf("the runtime is not restarted when %s changes: %s", want, restarts)
+		}
+	}
+	// After every bundle and the credential, so both exist before it starts.
+	names := ids(out)
+	if names[len(names)-1] != RuntimeModule+"."+RuntimeProcessID() {
+		t.Errorf("the runtime's process is not last: %v", names)
+	}
+
+	t.Run("a machine with no account runs it as root without the operator words", func(t *testing.T) {
+		out, err := Resolution{Node: "anchor", Modules: []Manifest{nftables, theRuntime(t)}}.Declaration(with)
+		if err != nil {
+			t.Fatal(err)
+		}
+		process := fileNamed(out, RuntimeModule+"."+RuntimeProcessID())
+		env := process["env"].(map[string]string)
+		if _, set := env[RuntimeOperatorAccount]; set {
+			t.Error("an operator account was named on a machine that has none")
+		}
+		if _, set := process["user"]; set {
+			t.Error("a user was set on a machine with no account")
+		}
+		if credential := fileNamed(out, RuntimeModule+"."+NeedID("broker")); credential == nil || credential["owner"] != nil {
+			t.Errorf("the runtime's credential was given an owner on a machine with no account: %v", credential)
+		}
+	})
+
+	t.Run("a runtime module built wrong is refused by name", func(t *testing.T) {
+		two := Manifest{Module: RuntimeModule, Version: "1", OwnSecrets: OwnSecrets{"broker": {Path: "/b"}},
+			Build: &Build{Artifacts: []Artifact{{Name: "runtime", Kind: ArtifactBundle, Language: "typescript",
+				Entrypoints: []string{"a.js", "b.js"}}}}}
+		resolved, err := two.Resolve([]Built{{Name: "runtime", Kind: ArtifactBundle,
+			Reference: ArtifactStoreScheme + "x/runtime/blobs/" + bundleDigest, Digest: bundleDigest}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		_, err = Resolution{Node: "anchor", Modules: []Manifest{resolved}}.Declaration(with)
+		if err == nil || !strings.Contains(err.Error(), "entrypoint") {
+			t.Errorf("a runtime bundle with two entrypoints was composed: %v", err)
+		}
+	})
+}

internal/catalogue/seats.go

@@ -96,10 +96,35 @@ var defaultSeats = []Seat{
 	// A build says what it does as it does it (novox/hq ADR 0157): `started` when work is taken,
 	// `log.<build id>` for every line, `built` for the outcome. The log's tail token is the build's
 	// id, so a reader follows one build by subject alone.
+	// **Node-scoped, and every holder takes from one queue** (novox/hq ADR 0190): a build is asked of
+	// the role, and whichever machine holding the seat is idle pulls it. One holder per machine is
+	// what the scope says; sharing the work is what a seat's queue has always done.
+	{Name: "node-build-agent", Scope: ScopeNode,
+		Accepts: []string{"build"}, Emits: []string{"started", "built", "log.*"}, Decision: "novox/hq ADR 0190"},
+	// **Retired by ADR 0190, kept while a manifest still claims it.** The one build machine's seat.
+	// A claim to a seat the mesh no longer defines is refused, and the module holding this one is
+	// assigned on a live machine until build-agent replaces it — removing the row first would make
+	// that machine unresolvable in the meantime. Deleted once no registered manifest claims it.
 	{Name: "mesh-build-machine", Scope: ScopeMesh,
-		Accepts: []string{"build"}, Emits: []string{"started", "built", "log.*"}, Decision: "novox/hq ADR 0121"},
+		Accepts: []string{"build"}, Emits: []string{"started", "built", "log.*"}, Decision: "novox/hq ADR 0190"},
 	{Name: "node-dns-resolver", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
-	{Name: "node-intrusion-prevention", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
+	// The intrusion prevention's verbs (novox/hq ADR 0179): what a person asks a machine's ban list
+	// whatever keeps it — who is banned and why, ban one address, let one go. Every holder serves all
+	// four; the jails themselves are composed from the modules the machine runs (to-be 31).
+	{Name: "node-intrusion-prevention", Scope: ScopeNode, Decision: "novox/hq ADR 0121",
+		Serves: []Verb{
+			{Name: "status", Description: "Every jail on this machine with how many it is watching and " +
+				"holding now, and the totals since the jail started; one jail's detail when named.",
+				Input: schema(map[string]string{"jail": "one jail (optional)"}, nil)},
+			{Name: "banned", Description: "Every address banned on this machine right now, with the jail " +
+				"that holds it and when the ban ends.",
+				Input: schema(map[string]string{"jail": "one jail (optional)"}, nil)},
+			{Name: "ban", Description: "Ban one address in one jail now, for the jail's ban time — an " +
+				"operator's act on the live ban list, which the mesh never writes itself.",
+				Input: schema(map[string]string{"ip": "the address", "jail": "the jail to hold it"}, []string{"ip", "jail"})},
+			{Name: "unban", Description: "Let one address go, from one jail or from every jail when none is named.",
+				Input: schema(map[string]string{"ip": "the address", "jail": "one jail (optional)"}, []string{"ip"})},
+		}},
 	// The packet filter's verbs (novox/hq ADR 0170): what a person asks a machine's filter whatever
 	// filter answers — the rules as enforced, reload the mesh's own, remove one thing the mesh did
 	// not write. Every holder serves all three; what differs by filter is the holder's own tools.
@@ -119,6 +144,12 @@ var defaultSeats = []Seat{
 				"active found firewall's chains. An operator's act, by name, never a flush.",
 				Input: schema(map[string]string{"where": "the rule set, as `node show` lists it"}, []string{"where"})},
 		}},
+	// The machine's service manager (novox/hq ADR 0177). The host applies every declared unit,
+	// system or user scope; the holder answers questions and operator acts about them, each verb
+	// taking the unit and an optional scope. The holder runs nothing of its own: its verbs are
+	// served by the node tools runtime (ADR 0175).
+	{Name: "node-service-manager", Scope: ScopeNode, Decision: "novox/hq ADR 0177",
+		Serves: serviceManagerVerbs()},
 	// 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"},
@@ -392,3 +423,36 @@ func SeatsWithAProtocol() []Seat {
 	}
 	return out
 }
+
+// serviceManagerVerbs is the contract every holder of node-service-manager serves (novox/hq ADR
+// 0177): the units on the machine in both scopes, read and acted on by name. Every verb takes an
+// optional scope — "system" when absent, "user" for the operator account's own manager — so a
+// caller asks for a user unit the way it asks for a system one.
+func serviceManagerVerbs() []Verb {
+	scoped := func(more map[string]string, required []string) map[string]any {
+		props := map[string]string{"scope": "\"system\" (the default) or \"user\": the operator account's own manager"}
+		for k, v := range more {
+			props[k] = v
+		}
+		return schema(props, required)
+	}
+	unit := map[string]string{"unit": "the unit's name, as the service manager knows it"}
+	return []Verb{
+		{Name: "units", Description: "The units the service manager knows in a scope, each with its load, active and sub state; narrowed to a pattern when asked.",
+			Input: scoped(map[string]string{"pattern": "a glob the unit's name must match (optional)"}, nil)},
+		{Name: "status", Description: "One unit as the service manager sees it now: its states, whether it starts at boot, its main process, and whether the mesh declares it.",
+			Input: scoped(unit, []string{"unit"})},
+		{Name: "start", Description: "Start one unit. For a unit the mesh declares, the answer says the host will restore what its declaration says at the next apply.",
+			Input: scoped(unit, []string{"unit"})},
+		{Name: "stop", Description: "Stop one unit; for a mesh-declared unit the answer says the host will restore its declared state.",
+			Input: scoped(unit, []string{"unit"})},
+		{Name: "restart", Description: "Restart one unit.",
+			Input: scoped(unit, []string{"unit"})},
+		{Name: "enable", Description: "Make one unit start at boot (or at the account's login, in user scope).",
+			Input: scoped(unit, []string{"unit"})},
+		{Name: "disable", Description: "Stop one unit starting at boot (or at login, in user scope).",
+			Input: scoped(unit, []string{"unit"})},
+		{Name: "journal", Description: "The last lines of one unit's journal.",
+			Input: scoped(map[string]string{"unit": unit["unit"], "lines": "how many lines from the end (default 100)"}, []string{"unit"})},
+	}
+}

internal/catalogue/seats_test.go

@@ -44,8 +44,10 @@ func TestTheSeatsAreAClosedSetAndEachNamesItsDecision(t *testing.T) {
 			delivered[s.Delivers] = s.Name
 		}
 	}
-	if len(Seats()) != 15 {
-		t.Errorf("the mesh defines %d seats rather than 14; the set is closed, so a change here is "+
+	// Seventeen since node-build-agent (novox/hq ADR 0190) — sixteen once the retired
+	// mesh-build-machine row goes, when no registered manifest claims it any more.
+	if len(Seats()) != 17 {
+		t.Errorf("the mesh defines %d seats rather than 17; the set is closed, so a change here is "+
 			"a decision (novox/hq ADR 0110): %s", len(Seats()), seatNames())
 	}
 }

internal/catalogue/verbs.go

@@ -145,6 +145,13 @@ var ControllerVerbs = []Verb{
 			"node":   "one machine; the whole mesh when absent",
 			"clear":  "\"true\" to remove the layer instead of setting it",
 		}, []string{"module"})},
+	{Name: "command", Description: "Run one command line of the controller's own, as you would type it at its " +
+		"shell — `node account g14 jochen`, `node show ace`, `module list` — and answer what it printed. The " +
+		"generic verb beside the named ones (novox/hq ADR 0154): everything the binary can do, without a verb " +
+		"per command. Any node may call any tool (ADR 0175), so nothing is held back here.",
+		Input: schema(map[string]string{
+			"command": "the command line, as the controller's binary takes it; quotes group a word with spaces",
+		}, []string{"command"})},
 	{Name: "build", Description: "Have the build machine build a repository. Answers at once with the build's id: " +
 		"`builds` with that id follows it line by line, and the module is registered when the outcome comes.",
 		Input: schema(map[string]string{

internal/inventory/bususers.go

@@ -42,6 +42,9 @@ const (
 	BusModule     = "module"
 	BusEnrolment  = "enrolment"
 	BusPerson     = "person"
+	// BusNodeTools is a machine's tool runtime (novox/hq ADR 0175): named like the module it
+	// stands for, recorded as what it is.
+	BusNodeTools = "node-tools"
 )
 
 // MintBusPassword makes a bus password and records its hash under a username, replacing whatever was

internal/inventory/catalogue.go

@@ -42,6 +42,11 @@ type Source struct {
 	// Seen is when the source was last looked at — by a build, by hand, or by the forge saying it
 	// moved. What a late report of an older move is judged against.
 	Seen time.Time
+	// Against is every artifact the build this manifest came from stood on, as recorded. Part of a
+	// module's provenance like the commit is, and what tells a built manifest's base when the manifest
+	// itself no longer carries its build (novox/hq to-be 38 WP2.4). Empty for a manifest handed over
+	// by hand, which carries its `build.on` itself.
+	Against []string
 }
 
 // Current reports whether what the mesh holds is what the source last had.
@@ -61,6 +66,32 @@ func (s Source) Current() bool {
 // gains a requirement, a claim, a resource. What matters is that the change is visible the next
 // time a node is resolved, which it is.
 func (i *Inventory) RegisterModule(ctx context.Context, m catalogue.Manifest, from Source) error {
+	// **Once the node's tool runtime is in the catalogue, the pattern it retires may not spread**
+	// (novox/hq ADR 0175, to-be 38 WP2.4): a module serving its tools from a container built on the
+	// runtime's image. Refused at registration, by name, for a module that is new to the catalogue
+	// or that was registered in another shape — the mechanism that keeps the old pattern from
+	// returning by habit. **Not refused for a module already registered in that shape**: the
+	// catalogue holds some thirty of them the day the runtime arrives, each moves to a bundle in
+	// its own change (to-be 38 WP4 onward), and a gate that refused every rebuild of every unmoved
+	// module in the meantime would stop the whole pipeline to make a point the record already makes.
+	// Before the runtime exists the pattern is accepted as it always was.
+	if m.Module != catalogue.RuntimeModule {
+		if why := catalogue.ToolContainerOnTheRuntime(m, from.Against); why != "" {
+			runtime, err := i.hasModule(ctx, catalogue.RuntimeModule)
+			if err != nil {
+				return err
+			}
+			if runtime {
+				already, err := i.registeredInThatShape(ctx, m.Module)
+				if err != nil {
+					return err
+				}
+				if !already {
+					return fmt.Errorf("%s is not registered: %s", m.Module, why)
+				}
+			}
+		}
+	}
 	raw, err := json.Marshal(m)
 	if err != nil {
 		return err
@@ -89,6 +120,36 @@ func (i *Inventory) RegisterModule(ctx context.Context, m catalogue.Manifest, fr
 	return err
 }
 
+// registeredInThatShape is whether the catalogue already holds this module as a tools container on
+// the runtime's image — judged from the manifest it holds and what that module's newest build stood
+// on, the same two things the gate judges a new registration by. False for a module the catalogue
+// does not hold.
+func (i *Inventory) registeredInThatShape(ctx context.Context, name string) (bool, error) {
+	held, err := i.Catalogue(ctx)
+	if err != nil {
+		return false, err
+	}
+	stored, has := held[name]
+	if !has {
+		return false, nil
+	}
+	against, err := i.BuiltAgainst(ctx)
+	if err != nil {
+		return false, err
+	}
+	return catalogue.ToolContainerOnTheRuntime(stored, against[name]) != "", nil
+}
+
+// hasModule is whether the catalogue holds a module of that name.
+func (i *Inventory) hasModule(ctx context.Context, name string) (bool, error) {
+	var one int
+	err := i.store.Pool().QueryRow(ctx, `select 1 from module where name = $1`, name).Scan(&one)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return false, nil
+	}
+	return err == nil, err
+}
+
 // SourceMoved records that a module's source has a newer commit than the mesh has built.
 //
 // This is the whole of noticing. Nothing here builds anything — it writes down that the two

internal/inventory/catalogue_test.go

@@ -685,3 +685,61 @@ func TestRegisteringWithoutProvenanceKeepsTheSeat(t *testing.T) {
 		t.Fatalf("a hand-registered manifest erased where the module comes from: %+v", got)
 	}
 }
+
+// Once the node's tool runtime is in the catalogue, a module serving its tools from a container
+// built on the runtime's image is refused at registration, naming the record (novox/hq ADR 0175,
+// to-be 38 WP2.4) — for a module new to the catalogue or one that had moved away from it; a module
+// already standing in that shape is rebuilt as before, so the catalogue's pipeline keeps running
+// while each moves (WP3's amendment). Before the runtime, it is accepted as it always was — so a
+// mesh converts in the order the design says and nothing is refused before there is anything to
+// move to.
+func TestAToolContainerIsRefusedOnceTheRuntimeIsRegistered(t *testing.T) {
+	inv := fresh(t)
+	ctx := t.Context()
+	filter := catalogue.Manifest{Module: "nftables", Version: "1", Tools: []string{"firewall_rules"},
+		Resources: []map[string]any{{"id": "runtime", "type": "container", "name": "mesh-nftables"}}}
+	stoodOn := []string{catalogue.ArtifactStoreScheme + "mesh-tools/runtime@sha256:" + strings.Repeat("d", 64)}
+
+	// Before the runtime exists the old pattern is accepted as it always was — and built, which is
+	// how the catalogue comes to know what the module stood on.
+	if err := inv.RegisterModule(ctx, filter, Source{Repository: "/r", Against: stoodOn}); err != nil {
+		t.Fatalf("before the runtime exists the old pattern is accepted: %v", err)
+	}
+	built := aBuild("nf1", "nftables", "")
+	built.Against = stoodOn
+	if err := inv.RecordBuild(ctx, built); err != nil {
+		t.Fatal(err)
+	}
+	runtime := catalogue.Manifest{Module: catalogue.RuntimeModule, Version: "1"}
+	if err := inv.RegisterModule(ctx, runtime, Source{Repository: "/r"}); err != nil {
+		t.Fatal(err)
+	}
+
+	// **A module already registered in that shape is rebuilt without complaint** (to-be 38 WP2.4 as
+	// amended by WP3): some thirty of them stand the day the runtime arrives, and each moves in its
+	// own change. The gate is against the pattern spreading, not against the pipeline running.
+	if err := inv.RegisterModule(ctx, filter, Source{Repository: "/r", Against: stoodOn}); err != nil {
+		t.Fatalf("a rebuild of a module that already had the pattern was refused: %v", err)
+	}
+	// A module new to the catalogue in that shape is refused, naming the record.
+	newcomer := filter
+	newcomer.Module = "lamp"
+	err := inv.RegisterModule(ctx, newcomer, Source{Repository: "/r", Against: stoodOn})
+	if err == nil || !strings.Contains(err.Error(), "ADR 0175") {
+		t.Fatalf("a new module in the old pattern was registered beside the runtime: %v", err)
+	}
+	// And a module that had moved its tools to a bundle may not come back to a container.
+	moved := filter
+	moved.Resources = nil
+	if err := inv.RegisterModule(ctx, moved, Source{Repository: "/r", Against: stoodOn}); err != nil {
+		t.Fatalf("a module whose tools are a bundle was refused: %v", err)
+	}
+	unbuilt := aBuild("nf2", "nftables", "")
+	if err := inv.RecordBuild(ctx, unbuilt); err != nil {
+		t.Fatal(err)
+	}
+	err = inv.RegisterModule(ctx, filter, Source{Repository: "/r", Against: stoodOn})
+	if err == nil || !strings.Contains(err.Error(), "ADR 0175") {
+		t.Fatalf("a module that had moved returned to the old pattern unrefused: %v", err)
+	}
+}

internal/inventory/dependencies.go

@@ -63,7 +63,7 @@ func dependenciesOf(entries []Entry, against map[string][]string, read map[strin
 		if r := repositoryKey(e.Source.Repository); r != "" {
 			byRepository[r] = append(byRepository[r], name)
 		}
-		if e.Manifest.ClaimsSeat("mesh-build-machine") {
+		if e.Manifest.ClaimsSeat("node-build-agent") || e.Manifest.ClaimsSeat("mesh-build-machine") {
 			builders = append(builders, name)
 		}
 	}

internal/inventory/dependencies_test.go

@@ -12,7 +12,7 @@ func TestDependenciesAreOneRelationWithTheirKinds(t *testing.T) {
 		return Entry{Manifest: catalogue.Manifest{Module: name}, Source: Source{Repository: repository}}
 	}
 	builder := entry("builder", "http://forge/novox/mesh-catalog.git")
-	builder.Manifest.Claims = []catalogue.Claim{{Name: "mesh-build-machine", Scope: catalogue.ScopeMesh}}
+	builder.Manifest.Claims = []catalogue.Claim{{Name: "node-build-agent", Scope: catalogue.ScopeNode}}
 	plugin := entry("shop-plugin", "http://forge/novox/mesh-catalog.git")
 	plugin.Manifest.Build = &catalogue.Build{On: []catalogue.BuildsOn{{Arg: "BASE", Module: "shop"}}}
 	entries := []Entry{

internal/link/builds.go

@@ -19,8 +19,17 @@ import (
 // act on or a declaration a node reconciles toward; a build is a request that takes minutes and has
 // exactly one answer. Too long for request/reply, too particular to be an event.
 
-// TheBuildMachine is the role a build is submitted to.
-const TheBuildMachine = "mesh-build-machine"
+// TheBuildMachine is the role a build is submitted to: node-scoped, held on every machine that
+// builds, and the work shared among them (novox/hq ADR 0190). The name stays for every caller; what
+// it names moved from the mesh's one build machine to whichever build agent is idle.
+//
+// **Switching a live mesh over, in order.** The old seat's stream and worker
+// (SEAT_MESH_BUILD_MACHINE, SEAT_MESH_BUILD_MACHINE_worker) stay on the bus until removed by hand,
+// and the builder module keeps draining them while it is assigned. From the moment a controller
+// with this name runs, new asks go to node-build-agent and wait in its stream until some machine
+// holds the seat. So: let the queued builds finish; roll this controller; register and assign
+// build-agent to the machines that build; unassign builder and forget it and its seat's stream.
+const TheBuildMachine = "node-build-agent"
 
 // BuildWork is where a build request lands, and BuildOutcome is where its result does. Derived from
 // the seat, so both sides name the role and neither names the other.

internal/link/builds_current_test.go

@@ -26,7 +26,7 @@ func TestTheOldBusAnnouncesABuildUnderBothNames(t *testing.T) {
 	if KeyRoleBuilt != "built" {
 		t.Fatalf("the role's event is %q, and a holder emits its verbs bare", KeyRoleBuilt)
 	}
-	if TheBuildMachine != "mesh-build-machine" {
+	if TheBuildMachine != "node-build-agent" {
 		t.Fatalf("the role is %q", TheBuildMachine)
 	}
 	// The two must differ, or one publish would serve both and this doubling would be pointless.

internal/link/builds_nats.go

@@ -126,29 +126,31 @@ func (m *natsMachine) Close() {
 	}
 }
 
-// Take binds to the role's worker and hands each request over, one at a time.
+// Take binds to the role's worker and pulls one request at a time, handing each over.
 //
 // **Bound, never created.** The work queue and the worker on it are the controller's to define
 // (design 25 §3), and a build machine reaches no part of the JetStream API — so a missing one is said
 // as the mesh's to answer rather than quietly created with whatever this client defaults to.
+//
+// **Pulled, one at a time, by whichever holder is free** (novox/hq ADR 0190). Every machine holding
+// the role binds this same worker; a machine asks for the next request only when it has finished
+// the last, so a slow machine never holds an ask an idle one could take, and a machine that took
+// five at once would run five container builds against one runtime and finish all of them slower
+// than the first.
 func (m *natsMachine) Take(ctx context.Context, do func(context.Context, Build)) error {
-	worker, found := broker.HolderConsumerFor(m.on, "builder",
+	worker, found := broker.HolderConsumerFor(m.on, "build-agent",
 		broker.DeclaredSeat{Name: m.seat, Accepts: []string{"build"}})
 	if !found {
 		return fmt.Errorf("%s accepts no work, so there is nothing for this machine to take", m.seat)
 	}
 
-	// One at a time, which the consumer's own ack-pending limit enforces rather than a prefetch
-	// setting: a machine that took five requests at once would run five container builds against one
-	// runtime and finish all of them slower than the first.
-	work := make(chan *nats.Msg, 1)
 	// **The consumer's own filter, not the one subject this machine cares about.** The client checks
 	// what is asked for against the consumer's filter and refuses anything that is not the same —
 	// "subject does not match consumer" — so subscribing `…accept.build` against a consumer filtered
 	// on `…accept.>` is rejected even though it is narrower. Learned twice now, on two different
 	// consumers, which is why it is written down here.
 	filter := worker.Filters[0]
-	sub, err := m.js.Context().ChanQueueSubscribe(filter, worker.Queue, work,
+	sub, err := m.js.Context().PullSubscribe(filter, worker.Name,
 		nats.Bind(worker.Stream, worker.Name), nats.ManualAck())
 	if err != nil {
 		return fmt.Errorf(
@@ -159,13 +161,27 @@ func (m *natsMachine) Take(ctx context.Context, do func(context.Context, Build))
 	m.sub = sub
 
 	for {
-		select {
-		case <-ctx.Done():
+		if ctx.Err() != nil {
 			return nil
-		case msg, ok := <-work:
-			if !ok {
-				return errors.New("the bus stopped delivering build work")
+		}
+		// One, and wait a while for it; an empty queue is a timeout, which is the normal state of a
+		// machine with nothing to build, and is asked again.
+		fetched, err := sub.Fetch(1, nats.Context(ctx))
+		switch {
+		case errors.Is(err, context.Canceled), errors.Is(err, context.DeadlineExceeded):
+			return nil
+		case errors.Is(err, nats.ErrTimeout):
+			continue
+		case err != nil:
+			if sub.IsValid() {
+				// A transient fault in asking — a reconnect, a slow server — is asked past rather
+				// than ending the machine; one that outlasts the ack wait redelivers nothing lost.
+				time.Sleep(time.Second)
+				continue
 			}
+			return fmt.Errorf("the bus stopped delivering build work: %w", err)
+		}
+		for _, msg := range fetched {
 			var request BuildRequest
 			if err := json.Unmarshal(msg.Data, &request); err != nil {
 				// Unreadable: terminated rather than retried, because the next attempt reads the same

internal/link/builds_nats_test.go

@@ -48,7 +48,7 @@ func aBusWithTheBuildRole(t *testing.T) *broker.JetStream {
 		t.Fatal(err)
 	}
 	clean := func() {
-		_ = js.Context().DeleteStream("SEAT_MESH_BUILD_MACHINE")
+		_ = js.Context().DeleteStream("SEAT_NODE_BUILD_AGENT")
 		for _, s := range broker.MeshStreams() {
 			_ = js.Context().PurgeStream(s.Name)
 		}
@@ -158,7 +158,7 @@ func TestNatsABuildIsTakenAndItsOutcomeReachesEverybody(t *testing.T) {
 	// And the work left the queue: a request a machine took and settled must not be given to another.
 	deadline := time.Now().Add(5 * time.Second)
 	for time.Now().Before(deadline) {
-		info, err := js.Context().StreamInfo("SEAT_MESH_BUILD_MACHINE")
+		info, err := js.Context().StreamInfo("SEAT_NODE_BUILD_AGENT")
 		if err == nil && info.State.Msgs == 0 {
 			return
 		}
@@ -177,7 +177,7 @@ func TestNatsABuildWaitsForAMachineRatherThanFailing(t *testing.T) {
 	if _, err := js.Context().Publish(BuildWork(), body); err != nil {
 		t.Fatal(err)
 	}
-	info, err := js.Context().StreamInfo("SEAT_MESH_BUILD_MACHINE")
+	info, err := js.Context().StreamInfo("SEAT_NODE_BUILD_AGENT")
 	if err != nil || info.State.Msgs != 1 {
 		t.Fatalf("the work did not queue: %+v %v", info, err)
 	}
@@ -245,3 +245,83 @@ func TestNatsWorkAMachineDidNotAnswerGoesBackToTheQueue(t *testing.T) {
 func quietLog() *log.Logger { return log.New(io.Discard, "", 0) }
 
 var _ = quietLog
+
+// Two machines holding the role share one queue (novox/hq ADR 0190): three asks, each machine takes
+// one and the third waits until one of them is done; an ask is never handed to a machine that is
+// busy; and a machine that stops mid-ask leaves its ask to the other.
+func TestNatsTwoMachinesShareTheWorkAndNeitherIsHandedMoreThanItCanTake(t *testing.T) {
+	js := aBusWithTheBuildRole(t)
+	ctx, stop := context.WithCancel(context.Background())
+	defer stop()
+
+	for _, id := range []string{"w-1", "w-2", "w-3"} {
+		body, _ := json.Marshal(BuildRequest{ID: id, Repository: "/r"})
+		if _, err := js.Context().Publish(BuildWork(), body); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	type taken struct{ machine, id string }
+	took := make(chan taken, 8)
+	release := map[string]chan struct{}{"anchor": make(chan struct{}), "laptop": make(chan struct{})}
+	machines := map[string]BuildMachine{}
+	for _, name := range []string{"anchor", "laptop"} {
+		name := name
+		m := MachineOverNATS(js, name)
+		machines[name] = m
+		defer m.Close()
+		go func() {
+			_ = m.Take(ctx, func(ctx context.Context, work Build) {
+				took <- taken{name, work.Request().ID}
+				<-release[name]
+				_ = work.Announce(ctx, BuildResult{ID: work.Request().ID, On: name})
+				_ = work.Done()
+			})
+		}()
+	}
+
+	// Each machine took exactly one, and they are different asks.
+	first := map[string]string{}
+	for i := 0; i < 2; i++ {
+		select {
+		case got := <-took:
+			if _, twice := first[got.machine]; twice {
+				t.Fatalf("%s was handed a second ask while busy with its first", got.machine)
+			}
+			first[got.machine] = got.id
+		case <-time.After(10 * time.Second):
+			t.Fatalf("only %d machine(s) took work; two idle holders should both have", len(first))
+		}
+	}
+	if first["anchor"] == first["laptop"] {
+		t.Fatalf("both machines took %q: the queue is not shared, it is copied", first["anchor"])
+	}
+	// The third waits: nobody is free.
+	select {
+	case got := <-took:
+		t.Fatalf("%s was handed %s while both machines were busy", got.machine, got.id)
+	case <-time.After(2 * time.Second):
+	}
+	// One finishes, and only then is the third taken — by that machine, the one that is free.
+	close(release["anchor"])
+	release["anchor"] = make(chan struct{})
+	select {
+	case got := <-took:
+		if got.machine != "anchor" {
+			t.Fatalf("the third ask went to %s, which is still busy", got.machine)
+		}
+	case <-time.After(10 * time.Second):
+		t.Fatal("the third ask was never taken after a machine became free")
+	}
+	// A machine that stops mid-ask leaves its ask unacknowledged, and the ack wait brings it round
+	// to whoever is left — the path TestNatsWorkAMachineDidNotAnswerGoesBackToTheQueue proves with
+	// an explicit hand-back, because the real wait is a minute. Here: the laptop goes, anchor
+	// finishes, and with nothing queued nothing more is taken by the machine that is left.
+	machines["laptop"].Close()
+	close(release["anchor"])
+	select {
+	case got := <-took:
+		t.Fatalf("%s took %s; the queue should be empty", got.machine, got.id)
+	case <-time.After(2 * time.Second):
+	}
+}