A served value may name the consumer it is served to (hq ADR 0188)

${consumer:as} and ${consumer:as:dns} in a serves block are filled per
consumer at resolution, and the one filled value reaches both ends: the
consumer's binding and its ${bound:...} substitutions, and the provider's
contributions entry as `derived`. A fact or alphabet the mesh does not have
is refused at parse; a consumer whose own file already holds the derived
value is refused at resolution, naming the placeholder to write instead.

Makefile

@@ -59,7 +59,7 @@ PROVISIONER_IMAGE ?= mesh-provision-postgres:$(VERSION)
 PROVISIONER_DEV_TAG ?= mesh-provision-postgres:development
 
 provisioner-image:
-	docker build -f examples/postgres-provisioner/Dockerfile \
+	docker build --build-arg GO_BASE=$(GO_BASE) -f examples/postgres-provisioner/Dockerfile \
 		-t $(PROVISIONER_IMAGE) -t $(PROVISIONER_DEV_TAG) .
 	@echo
 	@docker image inspect $(PROVISIONER_IMAGE) --format 'built {{.RepoTags}}  {{.Size}} bytes'
@@ -70,7 +70,7 @@ OBJECTSTORE_IMAGE ?= mesh-provision-objectstore:$(VERSION)
 OBJECTSTORE_DEV_TAG ?= mesh-provision-objectstore:development
 
 objectstore-image:
-	docker build -f examples/objectstore-provisioner/Dockerfile \
+	docker build --build-arg GO_BASE=$(GO_BASE) -f examples/objectstore-provisioner/Dockerfile \
 		-t $(OBJECTSTORE_IMAGE) -t $(OBJECTSTORE_DEV_TAG) .
 	@echo
 	@docker image inspect $(OBJECTSTORE_IMAGE) --format 'built {{.RepoTags}}  {{.Size}} bytes'
@@ -81,7 +81,7 @@ REDIS_PROVISIONER_IMAGE ?= mesh-provision-redis:$(VERSION)
 REDIS_PROVISIONER_DEV_TAG ?= mesh-provision-redis:development
 
 redis-provisioner-image:
-	docker build -f examples/redis-provisioner/Dockerfile \
+	docker build --build-arg GO_BASE=$(GO_BASE) -f examples/redis-provisioner/Dockerfile \
 		-t $(REDIS_PROVISIONER_IMAGE) -t $(REDIS_PROVISIONER_DEV_TAG) .
 	@echo
 	@docker image inspect $(REDIS_PROVISIONER_IMAGE) --format 'built {{.RepoTags}}  {{.Size}} bytes'
@@ -91,7 +91,7 @@ PROXY_IMAGE ?= mesh-route-proxy:$(VERSION)
 PROXY_DEV_TAG ?= mesh-route-proxy:development
 
 proxy-image:
-	docker build -f examples/route-proxy/Dockerfile -t $(PROXY_IMAGE) -t $(PROXY_DEV_TAG) .
+	docker build --build-arg GO_BASE=$(GO_BASE) -f examples/route-proxy/Dockerfile -t $(PROXY_IMAGE) -t $(PROXY_DEV_TAG) .
 	@echo
 	@docker image inspect $(PROXY_IMAGE) --format 'built {{.RepoTags}}  {{.Size}} bytes'
 

cmd/mesh-controller/adopting_test.go

@@ -95,11 +95,22 @@ func reportsReaching(t *testing.T, open *stores, reachable []link.Reach, held ..
 		// filter is not sent to one that has not. The anchor reports one, as a real host does; this
 		// fixture lacked it from 2026-09-28 and nothing ran the test (issue 177).
 		Outward: []string{"eth0"},
+		// And what filters it (ADR 0168): its front end, the runtime's own, and a chain a
+		// predecessor left in the runtime's user chain.
+		Filters: anchorFilters,
 	}); err != nil {
 		t.Fatal(err)
 	}
 }
 
+// anchorFilters is what the adopted anchor says filters it: ufw's chains, the runtime's, and a
+// predecessor's chain the mesh did not write.
+var anchorFilters = []link.Filter{
+	{Where: "table ip filter, chain ufw-reject-input", Owner: "found-firewall", Refuses: "reject"},
+	{Where: "table ip filter, chain DOCKER", Owner: "runtime", Refuses: `iifname != "docker0" oifname "docker0" drop`},
+	{Where: "table ip filter, chain DOCKER-USER", Owner: "other", Refuses: `iifname "eth0" tcp dport 6000 drop`},
+}
+
 var (
 	heldContainer = link.Held{ID: "hello-web.server", Module: "hello-web", Kind: "container",
 		Target: "hello-web", Since: time.Now()}
@@ -264,6 +275,20 @@ func TestConvergingPreviewsThenChangesAndAdoptingKeepsWhatWasTaken(t *testing.T)
 	if strings.Contains(preview, "15672") {
 		t.Errorf("a loopback listener is in the preview:\n%s", preview)
 	}
+	// What filters the machine now, and the fate of each (novox/hq ADR 0168): the predecessor's
+	// chain is named as not the mesh's and left, so the reader knows before the flip.
+	for _, want := range []string{
+		"table ip filter, chain DOCKER-USER",
+		"NOT THE MESH'S; left in force",
+		`iifname "eth0" tcp dport 6000 drop`,
+		"table ip filter, chain ufw-reject-input",
+		"the found firewall's; retired with it",
+		"the container runtime's own; left",
+	} {
+		if !strings.Contains(preview, want) {
+			t.Errorf("the preview does not say %q:\n%s", want, preview)
+		}
+	}
 	for _, line := range strings.Split(preview, "\n") {
 		if strings.Contains(line, "5000") && !strings.Contains(line, "WILL CLOSE") {
 			t.Errorf("an undeclared published port is not said to close: %s", line)

cmd/mesh-controller/adoption.go

@@ -29,6 +29,10 @@ func showMode(ctx context.Context, inv *inventory.Inventory, node inventory.Node
 		if said, err := inv.AdoptionOf(ctx, node.Name); err == nil && len(said.Strays) > 0 {
 			showStrays(said.Strays)
 		}
+		// And what filters it, truthfully (novox/hq ADR 0168): the mesh alone, or not.
+		if filtering, err := inv.FilteringOf(ctx, node.Name); err == nil {
+			showFiltering(filtering, false)
+		}
 		return nil
 	}
 	fmt.Printf("  mode              adopted since %s\n",
@@ -72,10 +76,65 @@ func showMode(ctx context.Context, inv *inventory.Inventory, node inventory.Node
 		}
 	}
 	showStrays(said.Strays)
+	if filtering, err := inv.FilteringOf(ctx, node.Name); err == nil {
+		showFiltering(filtering, true)
+	}
 	fmt.Printf("  as of             %s\n", said.At.Local().Format(time.DateTime))
 	return nil
 }
 
+// showFiltering says what filters a machine, with owners (novox/hq ADR 0168), and for a converged
+// machine the state of the firewall it was found with. A machine that has not said is not said to
+// be filtered by anything.
+func showFiltering(f inventory.Filtering, adopted bool) {
+	if len(f.Filters) == 0 && f.FoundFirewall == nil {
+		return
+	}
+	if fw := f.FoundFirewall; fw != nil && !adopted {
+		switch {
+		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 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 != "":
+			fmt.Printf("  found firewall    %s, found inactive — not by the mesh\n", fw.Kind)
+		default:
+			fmt.Printf("  found firewall    %s, inactive\n", fw.Kind)
+		}
+	}
+	if len(f.Filters) == 0 {
+		return
+	}
+	if f.Alone() {
+		fmt.Printf("  filtered by       the mesh alone (%s)\n", filterSummary(f.Filters))
+		return
+	}
+	fmt.Printf("  filtered by       NOT the mesh alone: %d rule set(s) the mesh did not write refuse traffic here\n", len(f.Others()))
+	for _, x := range f.Filters {
+		if x.Owner == inventory.FilterOther || x.Owner == inventory.FilterFoundFirewall {
+			fmt.Printf("  %-17s %s — %s: %s\n", "", x.Where, x.Owner, x.Refuses)
+		}
+	}
+	fmt.Printf("  %-17s and its own: %s\n", "", filterSummary(f.Filters))
+}
+
+// filterSummary counts a machine's filters by owner: "mesh 2, runtime 3, ban 1".
+func filterSummary(filters []inventory.Filter) string {
+	counts := map[string]int{}
+	for _, x := range filters {
+		counts[x.Owner]++
+	}
+	var parts []string
+	for _, owner := range []string{inventory.FilterMesh, inventory.FilterRuntime, inventory.FilterBan, inventory.FilterFoundFirewall, inventory.FilterOther} {
+		if n := counts[owner]; n > 0 {
+			parts = append(parts, fmt.Sprintf("%s %d", owner, n))
+		}
+	}
+	return strings.Join(parts, ", ")
+}
+
 // showStrays says what a machine runs that the mesh neither wrote nor holds (ADR 0163).
 func showStrays(strays []inventory.Stray) {
 	if len(strays) == 0 {
@@ -661,7 +720,11 @@ func converge(ctx context.Context, open *stores, node string, yes bool, digest s
 	}
 	derived := derivedFilter{rules: rules, foundation: with.Foundation, mesh: with.Mesh,
 		outward: plan.PublicDomain != "", outwardLinks: with.OutwardLinks}
-	preview, saw := previewOf(node, reported, derived, plan, taken, filter, runs[filter])
+	filtering, err := inv.FilteringOf(ctx, node)
+	if err != nil {
+		return "", err
+	}
+	preview, saw := previewOf(node, reported, filtering, derived, plan, taken, filter, runs[filter])
 	preview += "\n\n  preview " + saw
 	if !yes {
 		return preview + fmt.Sprintf("\n\nNothing has changed. Run `converge %s --yes %s` to do "+
@@ -731,7 +794,7 @@ func converge(ctx context.Context, open *stores, node string, yes bool, digest s
 // previewOf is what converging a node will change, before it changes it, and a short digest of
 // what it said: every reachable thing and its fate, the modules the flip takes and the filter. The
 // digest is what the flip is asked to act on, so it changes whenever any of those would.
-func previewOf(node string, reported inventory.Adoption, derived derivedFilter,
+func previewOf(node string, reported inventory.Adoption, filtering inventory.Filtering, derived derivedFilter,
 	plan catalogue.Resolution, taken []string, filter string, filterAssigned bool) (string, string) {
 	var said []string
 	var b strings.Builder
@@ -823,6 +886,30 @@ func previewOf(node string, reported inventory.Adoption, derived derivedFilter,
 		fmt.Fprintf(&b, "  the found firewall (%s) is disabled, never flushed: its configuration stays on disk\n", fw)
 	}
 	said = append(said, fmt.Sprintf("filter %s assigned=%t firewall=%s", filter, filterAssigned, fw))
+	// What filters the machine now, and the fate of each (novox/hq ADR 0168): the found firewall
+	// retired, the runtime's own and bans left, and what the mesh did not write left and named —
+	// so the reader knows before the flip that the machine will not be filtered by the mesh alone.
+	if len(filtering.Filters) > 0 {
+		b.WriteString("\n  what filters the machine now, and what the flip does to each:\n")
+		for _, x := range filtering.Filters {
+			fate := "left: " + x.Owner + "'s"
+			switch x.Owner {
+			case inventory.FilterMesh:
+				fate = "the mesh's guard; replaced by its filter"
+			case inventory.FilterFoundFirewall:
+				fate = "the found firewall's; retired with it"
+			case inventory.FilterRuntime:
+				fate = "the container runtime's own; left"
+			case inventory.FilterBan:
+				fate = "a ban list; left"
+			case inventory.FilterOther:
+				fate = "NOT THE MESH'S; left in force — the machine is not filtered by the mesh alone until you remove it"
+			}
+			fmt.Fprintf(&b, "    %-50s %s\n", x.Where, fate)
+			fmt.Fprintf(&b, "    %-50s   %s\n", "", x.Refuses)
+			said = append(said, "filter "+x.Owner+" "+x.Where)
+		}
+	}
 	// Sorted: the same account, reported in another order, is the same preview.
 	sort.Strings(said)
 	sum := sha256.Sum256([]byte(strings.Join(said, "\n")))

cmd/mesh-controller/build.go

@@ -607,6 +607,10 @@ type answers struct {
 	// a consequence of the refusals above: a node that does not resolve is not on the network, and
 	// a mesh whose hub is that node has no hub.
 	network string
+	// filtered is every converged machine that is not filtered by the mesh alone (novox/hq ADR
+	// 0168): what filters it beyond the mesh's own, the runtime's plumbing and bans, by name — a
+	// predecessor's chain, a found firewall in force again. Such a machine is not "all well".
+	filtered map[string]inventory.Filtering
 	// untaken is, per machine, each assigned module whose resources the machine is holding as it
 	// found them, and how many — a module that was assigned, sent, and is running none of what it
 	// declares because nothing has taken it (novox/hq ADR 0100, 04-ISSUES/125).

cmd/mesh-controller/modules.go

@@ -352,10 +352,14 @@ func settingsCommand(ctx context.Context, args []string) error {
 	switch args[0] {
 	case "set":
 		if len(positionals) != 2 {
-			return errors.New("settings set <module> <settings.json> [--node <node>]")
+			return errors.New("settings set <module> <settings.json | {…}> [--node <node>]")
 		}
-		raw, err := os.ReadFile(positionals[1])
-		if err != nil {
+		// A file, or the values themselves when they begin with `{` — which is how the mesh's own
+		// `settings` tool passes them, having no file to hand over (novox/hq issue 198).
+		var raw []byte
+		if strings.HasPrefix(strings.TrimSpace(positionals[1]), "{") {
+			raw = []byte(positionals[1])
+		} else if raw, err = os.ReadFile(positionals[1]); err != nil {
 			return err
 		}
 		var values map[string]any

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/readable.go

@@ -3,6 +3,7 @@ package main
 import (
 	"encoding/json"
 	"fmt"
+	"github.com/novox/mesh-controller/internal/inventory"
 	"sort"
 	"time"
 )
@@ -66,6 +67,21 @@ type meshStatus struct {
 	// **A document without this said an outage was a well mesh.** Read from what each machine
 	// reported, so it is the machine's account and not the mesh's take-time listing.
 	Untaken []machineUntaken `json:"untaken,omitempty"`
+	// Filtered is every converged machine that is not filtered by the mesh alone (novox/hq ADR
+	// 0168), one entry per rule set the mesh did not write — the found firewall in force again,
+	// or a chain nobody speaks for. Absent when every converged machine is filtered by the mesh
+	// alone. A document without this called a machine well while a predecessor's chain refused
+	// what the mesh declared open.
+	Filtered []machineFiltered `json:"filtered,omitempty"`
+}
+
+// machineFiltered is one rule set on a converged machine that the mesh did not write and that
+// refuses traffic: where it is, whose the host reads it as, and what it refuses.
+type machineFiltered struct {
+	Node    string `json:"node"`
+	Where   string `json:"where"`
+	Owner   string `json:"owner"`
+	Refuses string `json:"refuses"`
 }
 
 // machineUntaken is one module a machine is holding rather than running, and how many resources of
@@ -173,6 +189,21 @@ func statusAsJSON(asked answers) ([]byte, error) {
 				machineUntaken{Node: name, Module: m, Held: asked.untaken[name][m]})
 		}
 	}
+	filteredNodes := make([]string, 0, len(asked.filtered))
+	for name := range asked.filtered {
+		filteredNodes = append(filteredNodes, name)
+	}
+	sort.Strings(filteredNodes)
+	for _, name := range filteredNodes {
+		f := asked.filtered[name]
+		if fw := f.FoundFirewall; fw != nil && fw.Active {
+			out.Filtered = append(out.Filtered, machineFiltered{Node: name, Where: "the found firewall",
+				Owner: inventory.FilterFoundFirewall, Refuses: fw.Kind + " is in force again"})
+		}
+		for _, x := range f.Others() {
+			out.Filtered = append(out.Filtered, machineFiltered{Node: name, Where: x.Where, Owner: x.Owner, Refuses: x.Refuses})
+		}
+	}
 	for name := range asked.refused {
 		out.Unresolved = append(out.Unresolved, machineUnresolved{
 			Node: name, Problem: asked.refused[name]})

cmd/mesh-controller/readable_test.go

@@ -167,3 +167,46 @@ func TestAMachineFailingTheSameWayIsSaidToBeStuck(t *testing.T) {
 		t.Fatalf("one failure is not stuck: %v", once)
 	}
 }
+
+// A converged machine something other than the mesh filters is named, per rule set, and is not
+// well (novox/hq ADR 0168); one filtered by the mesh alone is not in the list.
+func TestAMachineNotFilteredByTheMeshAloneIsNamedAndNotWell(t *testing.T) {
+	alone := inventory.Filtering{Filters: []inventory.Filter{
+		{Where: "table inet mesh, chain input", Owner: inventory.FilterMesh, Refuses: "policy drop"},
+		{Where: "table ip filter, chain DOCKER", Owner: inventory.FilterRuntime, Refuses: "drop"},
+		{Where: "table ip filter, chain f2b-sshd", Owner: inventory.FilterBan, Refuses: "ip saddr 192.0.2.1 reject"},
+	}}
+	if !alone.Alone() {
+		t.Fatal("the mesh's own, the runtime's and a ban are not the mesh alone")
+	}
+	notAlone := inventory.Filtering{
+		Filters: append(alone.Filters, inventory.Filter{Where: "chain HAL-MESH-ONLY (iptables-legacy)",
+			Owner: inventory.FilterOther, Refuses: `-A HAL-MESH-ONLY -m comment --comment "not public" -j DROP`}),
+		FoundFirewall: &inventory.FoundFirewall{Kind: "ufw", Active: true},
+	}
+	asked := answers{nodes: []inventory.Node{{Name: "home-server"}, {Name: "laptop"}},
+		filtered: map[string]inventory.Filtering{"home-server": notAlone}}
+	if asked.well() {
+		t.Fatal("a machine not filtered by the mesh alone reads as well")
+	}
+	body, err := statusAsJSON(asked)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var parsed struct {
+		Filtered []map[string]string `json:"filtered"`
+	}
+	if err := json.Unmarshal(body, &parsed); err != nil {
+		t.Fatal(err)
+	}
+	if len(parsed.Filtered) != 2 {
+		t.Fatalf("filtered: %v", parsed.Filtered)
+	}
+	if parsed.Filtered[0]["node"] != "home-server" || parsed.Filtered[0]["owner"] != inventory.FilterFoundFirewall ||
+		parsed.Filtered[1]["where"] != "chain HAL-MESH-ONLY (iptables-legacy)" || parsed.Filtered[1]["owner"] != inventory.FilterOther {
+		t.Fatalf("filtered: %v", parsed.Filtered)
+	}
+	if body, _ := statusAsJSON(answers{nodes: asked.nodes}); strings.Contains(string(body), `"filtered"`) {
+		t.Fatal("a mesh filtered by itself alone carries a filtered list")
+	}
+}

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":
@@ -129,6 +144,25 @@ func argvFor(verb string, args map[string]any) ([]string, error) {
 		// Half of either shape: the command says its usage, which names both shapes, and that is
 		// the answer the caller needs.
 		return []string{"rotate"}, nil
+	case "settings":
+		// `settings set|clear` at a shell (novox/hq issue 198). The values travel as an argument
+		// because a tool has no file to hand the command; the command reads either.
+		if err := need("module"); err != nil {
+			return nil, err
+		}
+		argv := []string{"settings", "set", str("module")}
+		switch {
+		case str("clear") == "true":
+			argv = []string{"settings", "clear", str("module")}
+		case str("values") != "":
+			argv = append(argv, str("values"))
+		}
+		// Neither values nor clear: the command says its usage, which names both, and that is the
+		// answer the caller needs — the same as `rotate` given half of either shape.
+		if n := str("node"); n != "" {
+			argv = append(argv, "--node", n)
+		}
+		return argv, nil
 	case "issue":
 		// The same act as `module issue` at a shell (novox/hq design 25 §4): the account is minted
 		// into the mesh's records and delivered at the machine's next push, which is the caller's to
@@ -196,13 +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
@@ -213,8 +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{}
@@ -230,7 +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
@@ -270,3 +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"
 
@@ -73,6 +74,22 @@ func TestRotateTakesAProvisionOrAnOwnSecret(t *testing.T) {
 	}
 }
 
+// `settings` is `settings set|clear` at a shell, with the values passed inline (novox/hq issue 198).
+func TestSettingsSetsOrClearsALayer(t *testing.T) {
+	argv, err := argvFor("settings", map[string]any{"module": "dnsmasq", "values": `{"a":1}`, "node": "ace"})
+	if err != nil || strings.Join(argv, " ") != `settings set dnsmasq {"a":1} --node ace` {
+		t.Fatalf("set on a machine: %v %v", argv, err)
+	}
+	argv, _ = argvFor("settings", map[string]any{"module": "dnsmasq", "clear": "true"})
+	if strings.Join(argv, " ") != "settings clear dnsmasq" {
+		t.Fatalf("clear for the mesh: %v", argv)
+	}
+	argv, _ = argvFor("settings", map[string]any{"module": "dnsmasq"})
+	if strings.Join(argv, " ") != "settings set dnsmasq" {
+		t.Fatalf("a set with no values falls to the command's usage: %v", argv)
+	}
+}
+
 // `issue` is `module issue` at a shell: the module and the machine, and nothing that would push. A
 // module's bus account was mintable only from the controller's command line, so an agent working
 // through the tools could not finish a rollout that gave a module one (novox/hq issue 191).
@@ -114,10 +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))
 	}
@@ -155,3 +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)
+		}
+	}
+}

cmd/mesh-controller/status.go

@@ -227,6 +227,28 @@ func printStatus(asked answers) error {
 			"  not readable from a commit; that needs a version the host reports as ordered\n\n")
 	}
 
+	if len(asked.filtered) > 0 {
+		// A converged machine is filtered by the mesh alone, and the mesh says truthfully which
+		// (novox/hq ADR 0168). One that is not — a predecessor's chain still refusing, a found
+		// firewall in force again — is said here, and is not well.
+		machines := make([]string, 0, len(asked.filtered))
+		for name := range asked.filtered {
+			machines = append(machines, name)
+		}
+		sort.Strings(machines)
+		fmt.Printf("%d converged machine(s) are not filtered by the mesh alone:\n", len(machines))
+		for _, name := range machines {
+			f := asked.filtered[name]
+			if fw := f.FoundFirewall; fw != nil && fw.Active {
+				fmt.Printf("  %-12s the found firewall (%s) is in force again; the next apply retires it\n", name, fw.Kind)
+			}
+			for _, x := range f.Others() {
+				fmt.Printf("  %-12s %s (%s): %s\n", name, x.Where, x.Owner, x.Refuses)
+			}
+		}
+		fmt.Printf("\n  the mesh wrote none of these and removes none; `node show <node>` lists every filter with its owner\n\n")
+	}
+
 	if len(asked.untaken) > 0 {
 		// **Before the adopted line, and it breaks "all well".** An adopted machine is a state
 		// somebody chose and can leave alone; a module assigned to one and never taken is work
@@ -357,6 +379,13 @@ func theThreeQuestions(ctx context.Context, open *stores) (answers, error) {
 	if err != nil {
 		return answers{}, err
 	}
+	// And which converged machines something other than the mesh filters (novox/hq ADR 0168), as
+	// each last reported — the account that was missing when a predecessor's chain refused what the
+	// mesh declared open for eleven hours (04-ISSUES/144, 145).
+	out.filtered, err = filteredMachines(ctx, inv, out.nodes)
+	if err != nil {
+		return answers{}, err
+	}
 	out.plans, err = inv.RecentPlans(ctx, 5)
 	if err != nil {
 		return answers{}, err
@@ -406,6 +435,30 @@ func theThreeQuestions(ctx context.Context, open *stores) (answers, error) {
 //
 // A machine that reports no holds contributes nothing, so a converged mesh answers an empty map and
 // the caller prints nothing.
+// filteredMachines is every converged machine not filtered by the mesh alone, with what it last said
+// filters it (novox/hq ADR 0168). An adopted machine keeps its found firewall by design and is not
+// counted; a machine that has not said is not said to be filtered by anything.
+func filteredMachines(ctx context.Context, inv *inventory.Inventory, nodes []inventory.Node) (
+	map[string]inventory.Filtering, error) {
+	out := map[string]inventory.Filtering{}
+	for _, n := range nodes {
+		if n.Adopted {
+			continue
+		}
+		f, err := inv.FilteringOf(ctx, n.Name)
+		if err != nil {
+			return nil, fmt.Errorf("what filters %s cannot be read: %w", n.Name, err)
+		}
+		if len(f.Filters) == 0 && f.FoundFirewall == nil {
+			continue
+		}
+		if !f.Alone() {
+			out[n.Name] = f
+		}
+	}
+	return out, nil
+}
+
 func untakenModules(ctx context.Context, inv *inventory.Inventory, nodes []inventory.Node) (
 	map[string]map[string]int, error) {
 
@@ -442,7 +495,8 @@ func untakenModules(ctx context.Context, inv *inventory.Inventory, nodes []inven
 // read as success for the whole of the edge cut-over outage (novox/hq 04-ISSUES/125).
 func (a answers) well() bool {
 	return len(a.wrong) == 0 && len(a.quiet) == 0 && len(a.behind) == 0 &&
-		len(a.waiting) == 0 && len(a.refused) == 0 && a.network == "" && len(a.untaken) == 0
+		len(a.waiting) == 0 && len(a.refused) == 0 && a.network == "" && len(a.untaken) == 0 &&
+		len(a.filtered) == 0
 }
 
 // hostSplit is which machines report which host version, for every version more than one machine

examples/objectstore-provisioner/Dockerfile

@@ -10,7 +10,10 @@
 # The client is copied from the vendor's own image rather than installed from a distribution:
 # `apk add mc` on Alpine installs Midnight Commander, which is a different program with the same
 # name, and the failure would be a provisioner that starts cleanly and cannot do anything.
-FROM golang:1.25-alpine AS build
+# The Go it builds with is the one the manifest pins (build.on GO_BASE), passed by the Makefile and the
+# build machine alike; the default only serves a hand build, and matches go.mod.
+ARG GO_BASE=golang:1.26-alpine
+FROM ${GO_BASE} AS build
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download

examples/postgres-provisioner/Dockerfile

@@ -3,7 +3,10 @@
 # Built here so a machine can be given it by the mesh rather than by somebody putting a binary on
 # it. Static and FROM scratch for the same reason the control plane's image is: it is fetched by
 # digest and run on a machine, and everything in it is something a person would have to audit.
-FROM golang:1.25-alpine AS build
+# The Go it builds with is the one the manifest pins (build.on GO_BASE), passed by the Makefile and the
+# build machine alike; the default only serves a hand build, and matches go.mod.
+ARG GO_BASE=golang:1.26-alpine
+FROM ${GO_BASE} AS build
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download

examples/redis-provisioner/Dockerfile

@@ -2,7 +2,10 @@
 #
 # FROM scratch, like the postgres one and unlike the bucket one: it speaks the store's own wire
 # protocol directly and needs no client in the image.
-FROM golang:1.25-alpine AS build
+# The Go it builds with is the one the manifest pins (build.on GO_BASE), passed by the Makefile and the
+# build machine alike; the default only serves a hand build, and matches go.mod.
+ARG GO_BASE=golang:1.26-alpine
+FROM ${GO_BASE} AS build
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download

examples/route-proxy/Dockerfile

@@ -2,7 +2,10 @@
 #
 # Static and FROM scratch like the control plane's image, and for the same reason: it is fetched
 # by digest and run on a machine, so everything in it is something a person would have to audit.
-FROM golang:1.25-alpine AS build
+# The Go it builds with is the one the manifest pins (build.on GO_BASE), passed by the Makefile and the
+# build machine alike; the default only serves a hand build, and matches go.mod.
+ARG GO_BASE=golang:1.26-alpine
+FROM ${GO_BASE} AS build
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download

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/catalogue/bound_into_files.go

@@ -46,7 +46,7 @@ func boundUsed(content string) [][2]string {
 // Three facts the mesh states about any provision, plus whatever the provider said it serves. A
 // module may not reach a binding it does not have — the same boundary as a secret, for the same
 // reason.
-func knownFor(m Manifest, needs []Needed, node string) map[string]map[string]string {
+func knownFor(m Manifest, needs []Needed, node string) (map[string]map[string]string, error) {
 	out := map[string]map[string]string{}
 	for _, want := range m.Wants() {
 		for i := range needs {
@@ -54,12 +54,20 @@ func knownFor(m Manifest, needs []Needed, node string) map[string]map[string]str
 			if n.Name != want || n.For != m.Module {
 				continue
 			}
+			as := ConsumerIdentity(node, IdentitySource(m.Slug, m.Module))
 			values := map[string]string{
 				"at":   n.At,
 				"from": n.From,
-				"as":   ConsumerIdentity(node, IdentitySource(m.Slug, m.Module)),
+				"as":   as,
 			}
-			for key, value := range n.Serves {
+			// What the provider derives for this consumer rather than for all of them
+			// (novox/hq ADR 0188). Filled here, the one place a provision and the module
+			// requiring it are both in hand.
+			served, err := ServedTo(n.Serves, as)
+			if err != nil {
+				return nil, fmt.Errorf("%s requires %s: %w", m.Module, want, err)
+			}
+			for key, value := range served {
 				// The provider's own vocabulary. Rendered plainly: a port is 5432, not 5432.000000,
 				// which is what a float would write and what a connection string would refuse.
 				values[key] = plainly(value)
@@ -67,7 +75,7 @@ func knownFor(m Manifest, needs []Needed, node string) map[string]map[string]str
 			out[want] = values
 		}
 	}
-	return out
+	return out, nil
 }
 
 // withOwnNames adds a module's own composed names to what it may name from one binding:

internal/catalogue/consumer_into_serves.go

@@ -0,0 +1,290 @@
+package catalogue
+
+import (
+	"fmt"
+	"regexp"
+	"sort"
+	"strings"
+)
+
+// What a provider derives for one consumer, said once in the provider's definition and delivered
+// to both ends (novox/hq ADR 0188, issue 124).
+//
+// A `serves` block is otherwise literal: the same values for every consumer. Where the provider
+// *names the resource* — a bucket, a database, a vhost — the name is derived from who is asking,
+// and before this the mesh had no channel for it. The provider recomputed it in its own code and
+// every consumer transcribed it into its own definition by hand, which is a copy of somebody
+// else's rule kept in agreement by nobody. One of three transcriptions was wrong for months.
+//
+// **The mesh learns no protocol here; it spells its own name in an alphabet it already knows.**
+// The only fact a served value may name is the identity the mesh itself minted for the consumer,
+// in one of two alphabets: as it was minted, and as a DNS label. Everything a provider wants
+// around it — a prefix, a suffix, a separator — it writes around the placeholder, because a
+// served value is a string.
+
+// consumerFact is `${consumer:<fact>}` or `${consumer:<fact>:<alphabet>}`.
+var consumerFact = regexp.MustCompile(`\$\{consumer:([a-z][a-z0-9-]*)(?::([a-z][a-z0-9-]*))?\}`)
+
+// consumerFacts are what a served value may name about the consumer it is being derived for.
+// One entry, deliberately: the identity is the one thing about a consumer the mesh itself chose,
+// so it is the one thing the mesh can hand to a provider without either end guessing.
+var consumerFacts = []string{"as"}
+
+// consumerAlphabets are the ways the mesh will write that identity. `dns` is the mesh's own
+// identifier with its separator written `-` instead of `_` — the whole of the difference between
+// the alphabet the mesh mints in and the one buckets, vhosts and hostnames accept.
+var consumerAlphabets = []string{"dns"}
+
+// ServedTo fills a provider's served values for one consumer.
+//
+// `as` is the identity the mesh minted for that consumer — the same string it is told to present
+// as a login. Values with no placeholder are returned exactly as they were, and a block with no
+// placeholder at all is returned unchanged, so this costs nothing for the providers that derive
+// nothing.
+//
+// Only strings carry placeholders. A number, a boolean or a nested object is a value the provider
+// stated outright, and is left alone.
+func ServedTo(serves map[string]any, as string) (map[string]any, error) {
+	if len(serves) == 0 {
+		return serves, nil
+	}
+	var out map[string]any
+	for _, key := range sortedAnyKeys(serves) {
+		text, ok := serves[key].(string)
+		if !ok || !strings.Contains(text, "${consumer:") {
+			continue
+		}
+		filled, err := consumerInto(text, as)
+		if err != nil {
+			return nil, fmt.Errorf("the value served as %q: %w", key, err)
+		}
+		if out == nil {
+			// Copied only once something actually changes: the caller's map is the manifest's,
+			// and a provider that derives nothing must not have it rewritten underneath it.
+			out = make(map[string]any, len(serves))
+			for k, v := range serves {
+				out[k] = v
+			}
+		}
+		out[key] = filled
+	}
+	if out == nil {
+		return serves, nil
+	}
+	return out, nil
+}
+
+// consumerInto replaces every `${consumer:…}` in one value.
+//
+// **A fact or an alphabet the mesh does not have is refused, not left standing.** Written through,
+// the literal `${consumer:as}` would reach a configuration file and be read as a bucket name,
+// failing somewhere that names neither the module nor the mesh — the same reasoning `${bound:…}`
+// is refused by (boundInto).
+func consumerInto(value, as string) (string, error) {
+	var failed error
+	out := consumerFact.ReplaceAllStringFunc(value, func(match string) string {
+		parts := consumerFact.FindStringSubmatch(match)
+		fact, alphabet := parts[1], parts[2]
+		if fact != "as" {
+			if failed == nil {
+				failed = fmt.Errorf(
+					"says %s, and the mesh states %s about a consumer", match, orNothing(consumerFacts))
+			}
+			return match
+		}
+		switch alphabet {
+		case "":
+			return as
+		case "dns":
+			return asDNSLabel(as)
+		default:
+			if failed == nil {
+				failed = fmt.Errorf(
+					"says %s, and the mesh writes an identity as %s", match, orNothing(consumerAlphabets))
+			}
+			return match
+		}
+	})
+	if failed != nil {
+		return "", failed
+	}
+	return out, nil
+}
+
+// asDNSLabel writes a minted identity as a DNS label.
+//
+// The mesh's identities are already lower-case letters, digits and `_` (ConsumerIdentity), and
+// already short enough for the tightest backend they reach (CheckIdentity, twenty characters). So
+// this is the separator and nothing else — no lower-casing of what is already lower case, no
+// truncation to a limit the identity is already inside, no padding of a name that is already long
+// enough. Each of those would be the mesh guessing at a rule it has not been given.
+func asDNSLabel(as string) string {
+	return strings.ReplaceAll(as, "_", "-")
+}
+
+// CheckServes refuses a `serves` block that names a consumer fact or an alphabet the mesh does not
+// have, when the definition is parsed rather than when a consumer is resolved.
+//
+// A provision nobody consumes yet still has its rule read: a definition that would be refused the
+// first time somebody required it is a definition that is wrong now.
+func CheckServes(m Manifest) []string {
+	var problems []string
+	for _, provision := range sortedServes(m.Serves) {
+		for _, key := range sortedAnyKeys(m.Serves[provision]) {
+			text, ok := m.Serves[provision][key].(string)
+			if !ok {
+				continue
+			}
+			// A probe identity, because what is checked is the shape of the statement and not
+			// what any consumer is called.
+			if _, err := consumerInto(text, "mesh_node_module"); err != nil {
+				problems = append(problems, fmt.Sprintf(
+					"%s serves %s, and the value it serves as %q %s", m.Module, provision, key, err))
+			}
+		}
+	}
+	return problems
+}
+
+func sortedServes(serves map[string]map[string]any) []string {
+	out := make([]string, 0, len(serves))
+	for k := range serves {
+		out = append(out, k)
+	}
+	sort.Strings(out)
+	return out
+}
+
+func sortedAnyKeys(values map[string]any) []string {
+	out := make([]string, 0, len(values))
+	for k := range values {
+		out = append(out, k)
+	}
+	sort.Strings(out)
+	return out
+}
+
+// derivedFor is what the provider on this machine derives for one consumer of one provision
+// (novox/hq ADR 0188).
+//
+// Settled first, then derived: an operator may set a prefix on what the provider serves and the
+// mesh still fills the consumer's half of it ([ADR 0174]). Only the keys that actually name the
+// consumer are returned — the rest of a `serves` block is the same for every consumer and is
+// already in the provider's own definition, so repeating it here would be a second copy to go
+// stale.
+//
+// The first module in the resolved order that says it serves the provision answers, which is the
+// choice servedOnThisMachine makes for the consumer's half. Nothing serving it on this machine is
+// not an error: a contribution can reach a machine whose provider is a record or an adapter, and
+// then there is nothing derived to tell.
+func (r Resolution) derivedFor(provision, as string, settings SettingsBy) (map[string]any, error) {
+	for _, m := range r.Modules {
+		serves, said := m.Serves[provision]
+		if !said {
+			continue
+		}
+		var names map[string]any
+		for key, value := range serves {
+			if text, ok := value.(string); ok && strings.Contains(text, "${consumer:") {
+				if names == nil {
+					names = map[string]any{}
+				}
+				names[key] = value
+			}
+		}
+		if names == nil {
+			return nil, nil
+		}
+		settled, err := Settle(names, settings[m.Module])
+		if err != nil {
+			return nil, fmt.Errorf("%s serving %s: %w", m.Module, provision, err)
+		}
+		derived, err := ServedTo(settled, as)
+		if err != nil {
+			return nil, fmt.Errorf("%s serving %s to %s: %w", m.Module, provision, as, err)
+		}
+		return derived, nil
+	}
+	return nil, nil
+}
+
+// notTranscribed refuses a consumer's file that writes out the value its provider derives for it,
+// instead of asking for it (novox/hq ADR 0188, issue 124).
+//
+// **What would have caught the one wrong instance.** The object store's three consumers each wrote
+// their bucket into their own configuration by hand. One of them named a predecessor's bucket, and
+// nothing compared it to what the provider would actually create: the module would have
+// authenticated successfully and been refused on every object, which reads like a credential fault
+// and is not one. It looked authoritative for months.
+//
+// The test is exact and costs one string search: a definition whose file already contains the
+// value the mesh is about to derive for it has written down somebody else's rule. It cannot be a
+// coincidence — a derived value carries the identity the mesh minted for this very consumer on
+// this very machine, which nothing else would spell out — and it cannot be checked afterwards,
+// because after substitution every consumer's file contains it legitimately.
+//
+// Only values that actually name the consumer are judged. A provider that serves a constant under
+// the same key serves the same constant to everyone, and a consumer repeating it is redundant
+// rather than wrong.
+func notTranscribed(resource map[string]any, known map[string]map[string]string, module string) error {
+	if fmt.Sprint(resource["type"]) != "file" {
+		return nil
+	}
+	content, ok := resource["content"].(string)
+	if !ok || content == "" {
+		return nil
+	}
+	for _, provision := range sortedKnown(known) {
+		values := known[provision]
+		identity := values["as"]
+		if identity == "" {
+			continue
+		}
+		for _, key := range sortedStringKeys(values) {
+			if key == "as" {
+				// The login is not derived from itself, and a consumer that must present it in a
+				// connection string legitimately has it from `${bound:…}` — which is what it will
+				// be after substitution, so this would judge the substitution, not the module.
+				continue
+			}
+			value := values[key]
+			if value == "" || !namesTheConsumer(value, identity) {
+				continue
+			}
+			if !strings.Contains(content, value) {
+				continue
+			}
+			return fmt.Errorf(
+				"%s writes %q into %v, and that is exactly what %s derives for it — a definition "+
+					"keeping its own copy of somebody else's naming rule is one that can disagree "+
+					"with it, silently. Say ${bound:%s:%s} and be told",
+				module, value, resource["id"], provision, provision, key)
+		}
+	}
+	return nil
+}
+
+// namesTheConsumer is whether a derived value was built from this consumer's identity — in the
+// alphabet it was minted in, or as a DNS label. A value that does not contain it was not derived
+// from it, whatever else it may be.
+func namesTheConsumer(value, identity string) bool {
+	return strings.Contains(value, identity) || strings.Contains(value, asDNSLabel(identity))
+}
+
+func sortedKnown(known map[string]map[string]string) []string {
+	out := make([]string, 0, len(known))
+	for k := range known {
+		out = append(out, k)
+	}
+	sort.Strings(out)
+	return out
+}
+
+func sortedStringKeys(values map[string]string) []string {
+	out := make([]string, 0, len(values))
+	for k := range values {
+		out = append(out, k)
+	}
+	sort.Strings(out)
+	return out
+}

internal/catalogue/declaration.go

@@ -628,7 +628,16 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			if err != nil {
 				return nil, err
 			}
-			file, err := boundFile(*found, m.Binds[to], ConsumerIdentity(r.Node, IdentitySource(m.Slug, m.Module)), own)
+			as := ConsumerIdentity(r.Node, IdentitySource(m.Slug, m.Module))
+			// What the provider derives for THIS consumer, filled here where the consumer is
+			// known (novox/hq ADR 0188). The same fill knownFor does below, so the binding file
+			// and the module's `${bound:…}` substitutions cannot say different things.
+			told := *found
+			told.Serves, err = ServedTo(told.Serves, as)
+			if err != nil {
+				return nil, fmt.Errorf("%s is told about %s: %w", m.Module, to, err)
+			}
+			file, err := boundFile(told, m.Binds[to], as, own)
 			if err != nil {
 				return nil, err
 			}
@@ -694,7 +703,10 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			return nil, err
 		}
 		// And what its bindings say, for the half of a connection that is not secret.
-		known := knownFor(m, r.Needs, r.Node)
+		known, err := knownFor(m, r.Needs, r.Node)
+		if err != nil {
+			return nil, err
+		}
 		// A requirement answered on this same machine is not in r.Needs — its binding file is
 		// written from `here` (above) — and so `${bound:…}` could not name it, though the file
 		// beside it said the same facts. Filled from the same answer, so the two cannot disagree.
@@ -711,7 +723,11 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			}
 			local := *answered
 			local.For = m.Module
-			for provision, values := range knownFor(m, []Needed{local}, r.Node) {
+			here, err := knownFor(m, []Needed{local}, r.Node)
+			if err != nil {
+				return nil, err
+			}
+			for provision, values := range here {
 				known[provision] = values
 			}
 		}
@@ -736,6 +752,17 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 		// And the machine underneath, which no binding of its own can tell it.
 		thisMachine := machineFacts(r, with.Names, with.MeshRange)
 
+		// **A definition that already holds the answer transcribed it** (novox/hq ADR 0188).
+		// Judged over what the module itself declares, and before anything is substituted: the
+		// mesh's own generated files — the binding, the contributions — legitimately carry the
+		// derived value, and after substitution so does every consumer's file, so this is the one
+		// moment the two can be told apart.
+		for _, own := range m.Resources {
+			if err := notTranscribed(own, known, m.Module); err != nil {
+				return nil, err
+			}
+		}
+
 		// Which of this module's files carry a secret, for the rule that a container may not read
 		// one of them as its environment without saying so (ADR 0086, issue 041).
 		secretFiles := secretFilesOf(resources)
@@ -1100,6 +1127,19 @@ type Contribution struct {
 	// requirement's name — everything providing `reverse-proxy` understands the same shape, which
 	// is what makes swapping one for another cost nothing.
 	Values map[string]any `json:"values"`
+	// Derived is what this provider's own definition said it derives for this consumer, already
+	// derived (novox/hq ADR 0188).
+	//
+	// **The provider is told, rather than recomputing it.** A served value may name the consumer's
+	// identity — a bucket named for who is asking, a database prefixed with it — and before this
+	// the rule lived twice: once in the provisioner's code, once transcribed into every consumer's
+	// definition. The mesh fills the provider's own statement here and delivers the same filled
+	// value to the consumer, so the two cannot disagree: there is no second computation to
+	// disagree with.
+	//
+	// Only the keys that are per-consumer. The rest of what the provider serves is the same for
+	// everyone and is in its own definition, where it already is.
+	Derived map[string]any `json:"derived,omitempty"`
 }
 
 // grantPath is where one consumer's sealed credential lands on the providing machine.
@@ -1191,12 +1231,17 @@ func (r Resolution) contributions(settings SettingsBy, grants []Grant,
 			// told about it and withdraws the login on its next pass.
 			continue
 		}
+		as := holderAs(ConsumerIdentity(g.Consumer, IdentitySource(g.Slug, g.From)), g.Local)
+		derived, err := r.derivedFor(g.Provision, as, settings)
+		if err != nil {
+			return nil, err
+		}
 		out[g.Provision] = append(out[g.Provision], Contribution{
-			From: g.From, Node: g.Consumer, At: g.At, Values: g.Values,
+			From: g.From, Node: g.Consumer, At: g.At, Values: g.Values, Derived: derived,
 			// One holder per local name: the identity the consumer is known by, and the local name
 			// after it where the module keeps several (ADR 0094). Not a login any backend checks —
 			// a secret is not a login — so the identity limit does not apply to the suffix.
-			As:     holderAs(ConsumerIdentity(g.Consumer, IdentitySource(g.Slug, g.From)), g.Local),
+			As:     as,
 			Secret: grantPath(directories[g.Provision], g.Consumer, holderAs(g.From, g.Local)),
 		})
 		if granted[g.Provision] == nil {

internal/catalogue/derived_for_consumer_test.go

@@ -0,0 +1,297 @@
+package catalogue
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+// What a provider derives for each consumer, said once and delivered to both ends
+// (novox/hq ADR 0188, issue 124).
+//
+// The failure these are written against: the object store's provisioner derived each consumer's
+// bucket from the login the mesh minted, in its own code, and the mesh had no channel to tell the
+// consumer which bucket that was — so all three consumers wrote the answer into their own
+// definitions by hand. Two were right. One named a predecessor's bucket and would have
+// authenticated successfully and been refused on every object. Each of them also named the
+// machine the module happens to run on, which a definition may not do.
+
+// store is an object store in the shape minio has: it serves a region and a port to everyone, and
+// a bucket named for whoever is asking.
+func store() Manifest {
+	return Manifest{
+		Module: "store", Version: "1",
+		Provides: FromAnywhere("s3-bucket"),
+		Listens:  []Listening{{Port: 9000, Protocol: "tcp", From: FromMesh}},
+		Serves: map[string]map[string]any{"s3-bucket": {
+			"region": "eu-west",
+			"bucket": "${consumer:as:dns}",
+		}},
+		Receives: map[string]string{"s3-bucket": "/var/lib/store/grants/mesh.json"},
+		Grants:   map[string]string{"s3-bucket": "/var/lib/store/grants"},
+		Resources: []map[string]any{{
+			"id": "server", "type": "container", "name": "store", "ports": []any{"9000"},
+		}},
+	}
+}
+
+// files is a consumer that writes the bucket into its own configuration — which is the thing it
+// could not do before, and had to transcribe.
+func files() Manifest {
+	return Manifest{
+		Module: "files", Version: "1", Slug: "files",
+		Requires: []string{"s3-bucket"},
+		Binds:    map[string]string{"s3-bucket": "/var/lib/files/store.json"},
+		Secrets:  map[string]string{"s3-bucket": "/var/lib/files/store.secret"},
+		Resources: []map[string]any{{
+			"id": "env", "type": "file", "path": "/var/lib/files/env", "mode": "0600",
+			"content": "BUCKET=${bound:s3-bucket:bucket}\nREGION=${bound:s3-bucket:region}\n",
+		}},
+	}
+}
+
+// pics is a second consumer of the same provider on the same machine: two derivations, neither
+// the other's.
+func pics() Manifest {
+	return Manifest{
+		Module: "pics", Version: "1", Slug: "pics",
+		Requires: []string{"s3-bucket"},
+		Binds:    map[string]string{"s3-bucket": "/var/lib/pics/store.json"},
+		Secrets:  map[string]string{"s3-bucket": "/var/lib/pics/store.secret"},
+		Resources: []map[string]any{{
+			"id": "env", "type": "file", "path": "/var/lib/pics/env", "mode": "0600",
+			"content": "BUCKET=${bound:s3-bucket:bucket}\n",
+		}},
+	}
+}
+
+// The three places the derived value lands must agree, because agreeing is the whole point: the
+// consumer's own file, the binding it reads as JSON, and the provider's contributions entry.
+func TestADerivedValueReachesBothEndsAndAgrees(t *testing.T) {
+	r, err := Resolve(shelf(store(), files()), []string{"store", "files"}, reachable(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := r.Declaration(Rendering{Grants: []Grant{{
+		Provision: "s3-bucket", Consumer: "workstation", From: "files", Slug: "files",
+		Values: map[string]any{}, Sealed: "c2VhbGVk",
+	}}})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// The mesh minted this identity for the consumer; the bucket is that identity as a DNS label.
+	// Derived here with the mesh's own function, so the test cannot agree with a wrong rule.
+	as := ConsumerIdentity("workstation", IdentitySource("files", "files"))
+	want := strings.ReplaceAll(as, "_", "-")
+	if want == as || !strings.Contains(as, "_") {
+		t.Fatalf("the mesh's identity %q has no separator to rewrite; this test proves nothing", as)
+	}
+
+	env := fileNamed(out, "files.env")
+	if env == nil {
+		t.Fatalf("the consumer was given no file: %v", out)
+	}
+	if got := env["content"].(string); !strings.Contains(got, "BUCKET="+want+"\n") {
+		t.Errorf("the consumer's own file was not told the bucket:\n%s\nwant BUCKET=%s", got, want)
+	}
+
+	binding := fileNamed(out, "files.bound-s3-bucket")
+	if binding == nil {
+		t.Fatalf("the consumer was given no binding: %v", out)
+	}
+	var said struct {
+		Serves map[string]any `json:"serves"`
+	}
+	if err := json.Unmarshal([]byte(binding["content"].(string)), &said); err != nil {
+		t.Fatal(err)
+	}
+	if said.Serves["bucket"] != want {
+		t.Errorf("the binding says the bucket is %q, want %q", said.Serves["bucket"], want)
+	}
+	// And what is the same for everybody is still the same for everybody.
+	if said.Serves["region"] != "eu-west" {
+		t.Errorf("the binding lost what the provider serves to all: %v", said.Serves)
+	}
+
+	given := storeGrants(t, out)
+	if len(given) != 1 {
+		t.Fatalf("the provider was told about %d consumer(s): %v", len(given), given)
+	}
+	if given[0].Derived["bucket"] != want {
+		t.Errorf("the provider was told the bucket is %v, and the consumer was told %q — "+
+			"the two ends disagree, which is the whole failure", given[0].Derived["bucket"], want)
+	}
+	// Only the per-consumer half. The region is the same for everyone and is already in the
+	// provider's own definition; repeating it here would be a copy to go stale.
+	if _, carried := given[0].Derived["region"]; carried {
+		t.Errorf("the provider was handed back what it already says for everyone: %v", given[0].Derived)
+	}
+}
+
+// Two consumers of one provider on one machine get two buckets, and neither gets the other's.
+func TestTwoConsumersOfOneProviderGetTheirOwnDerivation(t *testing.T) {
+	r, err := Resolve(shelf(store(), files(), pics()),
+		[]string{"store", "files", "pics"}, reachable(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := r.Declaration(Rendering{Grants: []Grant{
+		{Provision: "s3-bucket", Consumer: "workstation", From: "files", Slug: "files",
+			Values: map[string]any{}, Sealed: "c2VhbGVk"},
+		{Provision: "s3-bucket", Consumer: "workstation", From: "pics", Slug: "pics",
+			Values: map[string]any{}, Sealed: "c2VhbGVk"},
+	}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	forFiles := strings.ReplaceAll(ConsumerIdentity("workstation", IdentitySource("files", "files")), "_", "-")
+	forPics := strings.ReplaceAll(ConsumerIdentity("workstation", IdentitySource("pics", "pics")), "_", "-")
+	if forFiles == forPics {
+		t.Fatal("the two consumers were given the same identity; this test proves nothing")
+	}
+	if got := fileNamed(out, "files.env")["content"].(string); !strings.Contains(got, "BUCKET="+forFiles+"\n") {
+		t.Errorf("files was not given its own bucket:\n%s", got)
+	}
+	if got := fileNamed(out, "pics.env")["content"].(string); !strings.Contains(got, "BUCKET="+forPics+"\n") {
+		t.Errorf("pics was not given its own bucket:\n%s", got)
+	}
+	var buckets []any
+	for _, g := range storeGrants(t, out) {
+		buckets = append(buckets, g.Derived["bucket"])
+	}
+	if len(buckets) != 2 || buckets[0] == buckets[1] {
+		t.Errorf("the provider was told %v; it must be told one bucket per consumer", buckets)
+	}
+}
+
+// An operator may still set what the provider serves, and the mesh still derives the rest: the
+// setting is laid on first, then the consumer's half is filled.
+func TestASettingComposesWithADerivedValue(t *testing.T) {
+	r, err := Resolve(shelf(store(), files()), []string{"store", "files"}, reachable(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := r.Declaration(Rendering{
+		Settings: SettingsBy{"store": {{From: "the operator",
+			Values: map[string]any{"bucket": "team-${consumer:as:dns}"}}}},
+		Grants: []Grant{{Provision: "s3-bucket", Consumer: "workstation", From: "files", Slug: "files",
+			Values: map[string]any{}, Sealed: "c2VhbGVk"}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := "team-" + strings.ReplaceAll(ConsumerIdentity("workstation", IdentitySource("files", "files")), "_", "-")
+	if got := fileNamed(out, "files.env")["content"].(string); !strings.Contains(got, "BUCKET="+want+"\n") {
+		t.Errorf("the operator's prefix did not survive the derivation:\n%s\nwant BUCKET=%s", got, want)
+	}
+	if given := storeGrants(t, out); given[0].Derived["bucket"] != want {
+		t.Errorf("the provider was told %v, the consumer %q", given[0].Derived["bucket"], want)
+	}
+}
+
+// A fact or an alphabet the mesh does not have is refused where the definition is, not where a
+// consumer happens to be resolved — and the refusal says what may be said instead.
+func TestAServedValueNamingSomethingTheMeshDoesNotHaveIsRefused(t *testing.T) {
+	for _, c := range []struct{ value, says string }{
+		{"${consumer:node}", "as"},
+		{"${consumer:as:punycode}", "dns"},
+	} {
+		m := store()
+		m.Serves["s3-bucket"]["bucket"] = c.value
+		raw, err := json.Marshal(m)
+		if err != nil {
+			t.Fatal(err)
+		}
+		_, err = ParseManifest(raw)
+		if err == nil {
+			t.Fatalf("%s was accepted", c.value)
+		}
+		if !strings.Contains(err.Error(), c.value) {
+			t.Errorf("the refusal of %s does not quote it: %v", c.value, err)
+		}
+		if !strings.Contains(err.Error(), c.says) {
+			t.Errorf("the refusal of %s does not say what may be said (%q): %v", c.value, c.says, err)
+		}
+	}
+}
+
+// `dns` is checked against an identity the mesh actually mints, not an invented string.
+func TestTheDNSAlphabetIsTheMintedIdentityWithItsSeparatorRewritten(t *testing.T) {
+	as := ConsumerIdentity("anchor", IdentitySource("ncloud", "nextcloud"))
+	if err := CheckIdentity("anchor", IdentitySource("ncloud", "nextcloud")); err != nil {
+		t.Fatalf("the mesh would not mint this identity at all: %v", err)
+	}
+	label := asDNSLabel(as)
+	if strings.Contains(label, "_") {
+		t.Errorf("%q is not a DNS label", label)
+	}
+	if strings.ReplaceAll(label, "-", "_") != as {
+		t.Errorf("%q is not %q with its separator rewritten", label, as)
+	}
+}
+
+// The check that would have caught the one wrong instance: a consumer that writes the derived
+// value into its own definition instead of asking for it is refused, whether it transcribed the
+// right answer or a predecessor's.
+func TestAConsumerThatTranscribesWhatItsProviderDerivesIsRefused(t *testing.T) {
+	as := ConsumerIdentity("workstation", IdentitySource("files", "files"))
+	transcribed := strings.ReplaceAll(as, "_", "-")
+
+	m := files()
+	m.Resources = []map[string]any{{
+		"id": "env", "type": "file", "path": "/var/lib/files/env", "mode": "0600",
+		// Exactly what the provider will create — correct today, and a copy of a rule that is
+		// not this module's.
+		"content": "BUCKET=" + transcribed + "\n",
+	}}
+	r, err := Resolve(shelf(store(), m), []string{"store", "files"}, reachable(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = r.Declaration(Rendering{Grants: []Grant{{
+		Provision: "s3-bucket", Consumer: "workstation", From: "files", Slug: "files",
+		Values: map[string]any{}, Sealed: "c2VhbGVk",
+	}}})
+	if err == nil {
+		t.Fatal("a definition holding its own copy of the provider's naming rule was accepted")
+	}
+	if !strings.Contains(err.Error(), "${bound:s3-bucket:bucket}") {
+		t.Errorf("the refusal does not say what to write instead: %v", err)
+	}
+
+	// And a constant the provider serves to everyone is not a transcription: repeating it is
+	// redundant, not wrong, and refusing it would be the mesh policing style.
+	m.Resources = []map[string]any{{
+		"id": "env", "type": "file", "path": "/var/lib/files/env", "mode": "0600",
+		"content": "REGION=eu-west\n",
+	}}
+	r, err = Resolve(shelf(store(), m), []string{"store", "files"}, reachable(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := r.Declaration(Rendering{Grants: []Grant{{
+		Provision: "s3-bucket", Consumer: "workstation", From: "files", Slug: "files",
+		Values: map[string]any{}, Sealed: "c2VhbGVk",
+	}}}); err != nil {
+		t.Errorf("a value the provider serves to everyone was judged a transcription: %v", err)
+	}
+}
+
+func storeGrants(t *testing.T, out []map[string]any) []Contribution {
+	t.Helper()
+	for _, r := range out {
+		if r["path"] != "/var/lib/store/grants/mesh.json" {
+			continue
+		}
+		var parsed struct {
+			Given []Contribution `json:"given"`
+		}
+		if err := json.Unmarshal([]byte(r["content"].(string)), &parsed); err != nil {
+			t.Fatal(err)
+		}
+		return parsed.Given
+	}
+	t.Fatalf("the provider was given no contributions file: %v", out)
+	return nil
+}

internal/catalogue/filtering.go

@@ -444,6 +444,18 @@ func AsNftables(rules []Rule, mesh []string, outward bool, foundation []int,
 		b.WriteString("\t\t# this machine's own guests reaching outward: not a port opened to anybody\n")
 		b.WriteString(fmt.Sprintf("\t\tiifname != { %s } accept\n", inward))
 	}
+	// **The mesh passing through, not arriving.** A machine the mesh routes through — the hub, for
+	// every path between machines that are not co-located (novox/hq ADR 0007) — relays a packet that
+	// came in on the tunnel and leaves on it again, addressed to another machine of the mesh. That is
+	// no port of this machine's: the machine it is for filters it against its own rules. Without
+	// this, the chain below judged a relayed packet by this machine's own published ports, so two
+	// machines behind the hub reached each other only on ports the hub happened to publish for itself
+	// (novox/hq issue 196). In and out on the tunnel both: a packet off the tunnel for this machine's
+	// own containers leaves by a bridge, and still meets the rules below.
+	if tunnel != "" {
+		b.WriteString("\t\t# the mesh passing through to another of its machines, which filters it itself\n")
+		b.WriteString(fmt.Sprintf("\t\tiifname %q oifname %q accept\n", tunnel, tunnel))
+	}
 
 	if len(rules) > 0 {
 		b.WriteString("\n")

internal/catalogue/filtering_test.go

@@ -887,3 +887,34 @@ func TestAPublicPortNeedsNoGuestLine(t *testing.T) {
 		t.Fatalf("a public port was given a guest line it does not need:\n%s", nft)
 	}
 }
+
+// **The hub relays the mesh** (novox/hq ADR 0007, issue 196). Two machines that are not co-located
+// reach each other through the hub, so the hub forwards a packet that arrives on the tunnel and
+// leaves on it. The forward chain judged that packet by the hub's own published ports, and two
+// machines behind the hub reached each other only on the ports the hub happened to publish.
+//
+// Measured: from one home machine to another through the hub, 17 of 55 ports answered, and they
+// were exactly the hub's own; the SYN for the rest never left the hub.
+func TestTheMeshPassingThroughIsRelayedNotJudgedAsThisMachines(t *testing.T) {
+	nft := AsNftables(nil, []string{"10.42.0.1", "10.42.0.2"}, false, nil, []string{"eth0"}, "mesh0")
+	relay := `iifname "mesh0" oifname "mesh0" accept`
+	if !strings.Contains(chainBody(t, nft, "forward"), relay) {
+		t.Errorf("the forward chain does not relay the mesh through this machine:\n%s", chainBody(t, nft, "forward"))
+	}
+	// Relaying is not receiving: nothing in the input chain opens because of it.
+	if strings.Contains(chainBody(t, nft, "input"), "oifname") {
+		t.Errorf("the input chain names an outgoing interface, which no packet for this machine has:\n%s",
+			chainBody(t, nft, "input"))
+	}
+	// And off the tunnel into this machine's own containers is still judged: the tunnel is not
+	// accepted wholesale, only in and out on it.
+	if strings.Contains(chainBody(t, nft, "forward"), `iifname "mesh0" accept`) {
+		t.Errorf("the forward chain accepts everything off the tunnel:\n%s", chainBody(t, nft, "forward"))
+	}
+
+	// A machine with no tunnel relays nothing, and names no interface it does not have.
+	alone := AsNftables(nil, nil, false, nil, []string{"eth0"}, "")
+	if strings.Contains(alone, "oifname") {
+		t.Errorf("a machine with no tunnel was given a relay rule:\n%s", alone)
+	}
+}

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

@@ -1360,6 +1360,10 @@ func ParseManifest(raw []byte) (Manifest, error) {
 				"%s serves %q to whoever requires it, and does not provide it", m.Module, to))
 		}
 	}
+	// A served value may be derived for the consumer it is served to (novox/hq ADR 0188). Read
+	// here, where the definition is, rather than when somebody first requires it: a rule that
+	// would be refused at the first consumer is wrong from the moment it is written.
+	problems = append(problems, CheckServes(m)...)
 	for to, where := range m.Binds {
 		if !placedOrAbsolute(where) {
 			problems = append(problems, fmt.Sprintf(
@@ -1667,6 +1671,7 @@ 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)
@@ -1769,6 +1774,46 @@ func (m Manifest) MachineSide(port int) (at int, mayAssign bool) {
 var facilitiesOf = map[string][]string{
 	// Both spellings: /var/run is a link to /run on every machine the mesh runs on.
 	"container-runtime": {"/var/run/docker.sock", "/run/docker.sock"},
+	// The virtualisation daemon's socket, for the lab (novox/hq ADR 0172): it raises machines there.
+	"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.
@@ -1810,6 +1855,12 @@ func (m Manifest) undeclaredMounts() []string {
 			claim(p)
 		}
 	}
+	// The file a filter module's rule set is written to is declared by `filtering.into`: the mesh
+	// writes it, the module loads it, and the module's runtime may read it back to reload the
+	// mesh's own table (novox/hq ADR 0170).
+	if m.Filtering != nil {
+		claim(m.Filtering.Into)
+	}
 	// Under a declared directory is declared: a module that says where its data lives has said so
 	// for what it puts inside.
 	covers := func(path string) bool {

internal/catalogue/mounts_test.go

@@ -98,3 +98,13 @@ func TestAMountOfABoundFactIsAccepted(t *testing.T) {
 		t.Fatalf("a mount of the file the mesh writes a binding to was refused: %v", err)
 	}
 }
+
+// The file a filter module's rule set is written to is declared by `filtering.into` (novox/hq ADR
+// 0169): the module's runtime mounts it to reload the mesh's own table, and nothing else declares it.
+func TestAMountOfTheFilterFileIsDeclaredByFilteringInto(t *testing.T) {
+	_, err := ParseManifest([]byte(`{"module":"nftables","filtering":{"into":"/etc/nftables.conf"},` +
+		`"resources":[` + strings.Replace(aContainerMounting, "%s", "/etc/nftables.conf", 1) + `]}`))
+	if err != nil {
+		t.Fatalf("a filter module mounting its own filter file was refused: %v", err)
+	}
+}

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/resolver_manifests_test.go

@@ -48,7 +48,9 @@ func TestTheResolverForwardsToFixedUpstreamsAndNeverReadsResolvConf(t *testing.T
 	}
 	for _, want := range []string{
 		"\nno-resolv\n", "\nserver=1.1.1.1\n", "\nserver=8.8.8.8\n",
-		"\nlisten-address=127.0.0.1\n", "\nlisten-address=${machine:address}\n", "\nbind-dynamic\n",
+		// Loopback is the mesh-wide setting's default; a machine answering its own LAN adds its
+		// address there (novox/hq issue 198).
+		"\nlisten-address=${setting:listen-addresses}\n", "\nlisten-address=${machine:address}\n", "\nbind-dynamic\n",
 		"\ndomain-needed\n", "\nbogus-priv\n",
 		"\nconf-file=" + m.Facts["node-zones"].Path + "\n",
 	} {
@@ -113,7 +115,8 @@ func TestTheResolverAndWhatAsksItComposeOnOneMachine(t *testing.T) {
 		// issue 111) — the resolver's zones read only the second, and in this scenario the two
 		// happen to be the same map, since nothing routed is part of it.
 		Names: twoMachines, Machines: twoMachines, Suffix: "internal",
-		Needed: map[string]map[string]string{"dnsmasq": {"broker": "sealed"}},
+		Needed:   map[string]map[string]string{"dnsmasq": {"broker": "sealed"}},
+		Settings: SettingsBy{"dnsmasq": {{From: "the mesh", Values: map[string]any{"listen-addresses": "127.0.0.1"}}}},
 	})
 	if err != nil {
 		t.Fatal(err)
@@ -207,9 +210,16 @@ func TestTheResolverOnAMachineOffTheNetworkIsRefused(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	_, err = got.Declaration(Rendering{Names: twoMachines, Suffix: "internal",
-		Needed: map[string]map[string]string{"dnsmasq": {"broker": "sealed"}}})
-	if err == nil || !strings.Contains(err.Error(), "${machine:address}") {
-		t.Fatalf("a machine off the network was composed a resolver, or refused for another reason: %v", err)
+	// Left out of the declaration and said, rather than composed listening nowhere: a module that
+	// cannot compose on a machine is kept as it is there, with the reason (hq ADR 0163).
+	composed, err := got.Compose(Rendering{Names: twoMachines, Suffix: "internal",
+		Needed:   map[string]map[string]string{"dnsmasq": {"broker": "sealed"}},
+		Settings: SettingsBy{"dnsmasq": {{From: "the mesh", Values: map[string]any{"listen-addresses": "127.0.0.1"}}}}})
+	if err == nil && !strings.Contains(composed.LeftOut["dnsmasq"], "${machine:address}") {
+		t.Fatalf("a machine off the network was composed a resolver, or left out for another reason: %v",
+			composed.LeftOut)
+	}
+	if err != nil && !strings.Contains(err.Error(), "${machine:address}") {
+		t.Fatalf("a machine off the network was refused for another reason: %v", err)
 	}
 }

internal/catalogue/seats.go

@@ -99,8 +99,48 @@ var defaultSeats = []Seat{
 	{Name: "mesh-build-machine", Scope: ScopeMesh,
 		Accepts: []string{"build"}, Emits: []string{"started", "built", "log.*"}, Decision: "novox/hq ADR 0121"},
 	{Name: "node-dns-resolver", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
-	{Name: "node-intrusion-prevention", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
-	{Name: "node-packet-filter", Scope: ScopeNode, Decision: "novox/hq ADR 0121"},
+	// 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.
+	{Name: "node-packet-filter", Scope: ScopeNode, Decision: "novox/hq ADR 0121",
+		Serves: []Verb{
+			{Name: "rules", Description: "The packet filter as this machine enforces it now: the nftables " +
+				"ruleset and, where the tool exists, the legacy filter's listings. Narrowed to one table or " +
+				"chain when asked.",
+				Input: schema(map[string]string{"table": "one nftables table, as `family name` (optional)",
+					"chain": "one chain of that table (optional)"}, nil)},
+			{Name: "reload", Description: "Load the mesh's own filter again from the file the mesh writes, " +
+				"and answer with the mesh's table as loaded.",
+				Input: schema(map[string]string{}, nil)},
+			{Name: "remove", Description: "Remove one rule set the mesh did not write, named exactly as the " +
+				"host reports it (novox/hq ADR 0168) — `chain X (iptables-legacy)` or `table ip6 filter, chain " +
+				"DOCKER-USER`. Refuses the mesh's tables, the runtime's own chains, a built-in chain and an " +
+				"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"},
@@ -374,3 +414,36 @@ 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 +44,9 @@ 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 "+
+	// Sixteen since node-service-manager (novox/hq ADR 0177).
+	if len(Seats()) != 16 {
+		t.Errorf("the mesh defines %d seats rather than 16; the set is closed, so a change here is "+
 			"a decision (novox/hq ADR 0110): %s", len(Seats()), seatNames())
 	}
 }

internal/catalogue/verbs.go

@@ -136,6 +136,22 @@ var ControllerVerbs = []Verb{
 			"node":   "the machine that runs the module",
 			"module": "the module's name",
 		}, []string{"node", "module"})},
+	{Name: "settings", Description: "Set what an assignment is configured with: a module's settings for the whole mesh, " +
+		"or for one machine. Replaces that layer whole — what it does not name, it no longer sets — and takes effect " +
+		"at the next push. With clear, removes the layer and the module is back to what its definition says.",
+		Input: schema(map[string]string{
+			"module": "the module's name",
+			"values": "the settings as a JSON object, for set",
+			"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/adoption.go

@@ -178,6 +178,103 @@ type Stray struct {
 	Detail string `json:"detail,omitempty"`
 }
 
+// A Filter is one place on a machine that refuses traffic, with its owner (novox/hq ADR 0168).
+type Filter struct {
+	Where   string `json:"where"`
+	Owner   string `json:"owner"`
+	Refuses string `json:"refuses"`
+}
+
+// Owners of a filter, as the host names them (ADR 0168).
+const (
+	FilterMesh          = "mesh"
+	FilterFoundFirewall = "found-firewall"
+	FilterRuntime       = "runtime"
+	FilterBan           = "ban"
+	FilterOther         = "other"
+)
+
+// FoundFirewall is the state of a converged machine's found firewall (ADR 0168): in force now or
+// not, and how it came to be inactive.
+type FoundFirewall struct {
+	Kind      string `json:"kind"`
+	Active    bool   `json:"active"`
+	RetiredBy string `json:"retired_by,omitempty"`
+}
+
+// Filtering is what a machine last said filters it (ADR 0168).
+type Filtering struct {
+	Filters       []Filter
+	FoundFirewall *FoundFirewall
+}
+
+// Alone is whether the machine is filtered by the mesh alone: nothing in its list but the mesh's
+// own, the runtime's plumbing and bans, and no found firewall in force.
+func (f Filtering) Alone() bool {
+	for _, x := range f.Filters {
+		if x.Owner == FilterOther || x.Owner == FilterFoundFirewall {
+			return false
+		}
+	}
+	return f.FoundFirewall == nil || !f.FoundFirewall.Active
+}
+
+// Others is every filter that is neither the mesh's, the runtime's nor a ban.
+func (f Filtering) Others() []Filter {
+	var out []Filter
+	for _, x := range f.Filters {
+		if x.Owner == FilterOther || x.Owner == FilterFoundFirewall {
+			out = append(out, x)
+		}
+	}
+	return out
+}
+
+// RecordFiltering keeps what a machine last said filters it, replacing what was there (ADR 0168).
+func (i *Inventory) RecordFiltering(ctx context.Context, nodeID string, filters []Filter, found *FoundFirewall) error {
+	raw, err := json.Marshal(nonNil(filters))
+	if err != nil {
+		return err
+	}
+	var foundRaw any
+	if found != nil {
+		b, err := json.Marshal(found)
+		if err != nil {
+			return err
+		}
+		foundRaw = string(b)
+	}
+	_, err = i.store.Pool().Exec(ctx,
+		`update node set filters = $2, found_firewall = $3 where id = $1`, nodeID, raw, foundRaw)
+	return err
+}
+
+// FilteringOf is what a machine last said filters it; empty for a machine that never said.
+func (i *Inventory) FilteringOf(ctx context.Context, name string) (Filtering, error) {
+	var filtersRaw, foundRaw []byte
+	err := i.store.Pool().QueryRow(ctx,
+		`select filters, found_firewall from node where name = $1`, name).Scan(&filtersRaw, &foundRaw)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return Filtering{}, fmt.Errorf("%w: %s", ErrNoSuchNode, name)
+	}
+	if err != nil {
+		return Filtering{}, err
+	}
+	var out Filtering
+	if len(filtersRaw) > 0 {
+		if err := json.Unmarshal(filtersRaw, &out.Filters); err != nil {
+			return Filtering{}, err
+		}
+	}
+	if len(foundRaw) > 0 {
+		out.FoundFirewall = &FoundFirewall{}
+		if err := json.Unmarshal(foundRaw, out.FoundFirewall); err != nil {
+			return Filtering{}, err
+		}
+	}
+	return out, nil
+}
+
 // Reach is one thing reachable on an adopted node: a listening socket or a published port.
 type Reach struct {
 	Protocol      string `json:"protocol"`

internal/inventory/migrations/0054-a-machine-says-what-filters-it.sql

@@ -0,0 +1,7 @@
+-- What filters a machine, with owners, as the host reports it with every apply (novox/hq ADR 0168):
+-- every table and chain that refuses traffic — the mesh's, the found firewall's, the runtime's own,
+-- a ban, or other — so the mesh says truthfully what filters a converged machine and names what it
+-- did not write. And the state of the firewall a converged machine was found with: in force now or
+-- not, and who retired it.
+alter table node add column filters jsonb;
+alter table node add column found_firewall jsonb;

internal/link/enrolment.go

@@ -305,6 +305,23 @@ func (e Enrolment) Heard(ctx context.Context, report Report) (news bool, err err
 			return false, err
 		}
 	}
+	// What filters the machine, and the state of its found firewall (novox/hq ADR 0168), whenever
+	// it says — every apply of a host that knows how, adopted or converged; never cleared by a
+	// report that carries none, which is every bare word that the node is there.
+	if len(report.Filters) > 0 || report.FoundFirewall != nil {
+		filters := make([]inventory.Filter, 0, len(report.Filters))
+		for _, f := range report.Filters {
+			filters = append(filters, inventory.Filter{Where: f.Where, Owner: f.Owner, Refuses: f.Refuses})
+		}
+		var found *inventory.FoundFirewall
+		if report.FoundFirewall != nil {
+			found = &inventory.FoundFirewall{Kind: report.FoundFirewall.Kind, Active: report.FoundFirewall.Active,
+				RetiredBy: report.FoundFirewall.RetiredBy}
+		}
+		if err := e.Inventory.RecordFiltering(ctx, node.ID, filters, found); err != nil {
+			return false, err
+		}
+	}
 	// Which of its links face outside (novox/hq ADR 0140), whenever it says so. Recorded on every
 	// report that carries it, adopted or converged, because the filter the mesh composes is written
 	// around it — and never cleared by a report that carries none, which is every bare word that the

internal/link/heard_test.go

@@ -218,3 +218,45 @@ func TestWhatAnAdoptedNodeHoldsIsKeptAndAnAliveWordDoesNotWipeIt(t *testing.T) {
 		t.Fatalf("a report from an adopted node holding nothing did not empty held: %+v", got)
 	}
 }
+
+// What filters a machine, and the state of its found firewall, are kept from every report that
+// carries them and never cleared by one that does not (novox/hq ADR 0168).
+func TestWhatFiltersAMachineIsKeptFromItsReport(t *testing.T) {
+	inv, _, _ := heardFrom(t, link.Report{
+		Node: "home-server", Applied: []string{"a"},
+		Filters: []link.Filter{
+			{Where: "table inet mesh, chain forward", Owner: "mesh", Refuses: "policy drop"},
+			{Where: "chain HAL-MESH-ONLY (iptables-legacy)", Owner: "other", Refuses: "-j DROP"},
+		},
+		FoundFirewall: &link.FoundFirewall{Kind: "ufw", Active: false, RetiredBy: "found-inactive"},
+	})
+	ctx := context.Background()
+	f, err := inv.FilteringOf(ctx, "home-server")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(f.Filters) != 2 || f.Filters[1].Owner != inventory.FilterOther || f.Alone() {
+		t.Fatalf("recorded %+v", f)
+	}
+	if f.FoundFirewall == nil || f.FoundFirewall.RetiredBy != "found-inactive" || f.FoundFirewall.Active {
+		t.Fatalf("the found firewall's state: %+v", f.FoundFirewall)
+	}
+	if len(f.Others()) != 1 || f.Others()[0].Where != "chain HAL-MESH-ONLY (iptables-legacy)" {
+		t.Fatalf("others: %+v", f.Others())
+	}
+	// A bare word that the node is there clears nothing.
+	if _, err := (link.Enrolment{Inventory: inv}).Heard(ctx, link.Report{Node: "home-server"}); err != nil {
+		t.Fatal(err)
+	}
+	if again, _ := inv.FilteringOf(ctx, "home-server"); len(again.Filters) != 2 {
+		t.Fatalf("a bare report cleared what filters the machine: %+v", again)
+	}
+	// The next full report replaces it: the chain removed by hand is gone from the record.
+	if _, err := (link.Enrolment{Inventory: inv}).Heard(ctx, link.Report{Node: "home-server", Applied: []string{"a"},
+		Filters: []link.Filter{{Where: "table inet mesh, chain forward", Owner: "mesh", Refuses: "policy drop"}}}); err != nil {
+		t.Fatal(err)
+	}
+	if again, _ := inv.FilteringOf(ctx, "home-server"); len(again.Filters) != 1 || !again.Alone() {
+		t.Fatalf("the next report did not replace what filters the machine: %+v", again)
+	}
+}

internal/link/protocol.go

@@ -197,6 +197,15 @@ type Report struct {
 	// Strays is what runs on the machine that the mesh neither wrote nor holds (ADR 0163).
 	Strays []Stray `json:"strays,omitempty"`
 
+	// Filters is what filters the machine now: every table and chain that refuses traffic, with
+	// its owner — the mesh's, the found firewall's, the container runtime's own, a ban, or other
+	// (novox/hq ADR 0168). Every machine reports it, adopted or converged; absent from a host older
+	// than this.
+	Filters []Filter `json:"filters,omitempty"`
+	// FoundFirewall is the state of the firewall a converged machine was found with: in force now
+	// or not, and how it came to be inactive — the mesh disabled it, or it was found so (ADR 0168).
+	FoundFirewall *FoundFirewall `json:"found_firewall,omitempty"`
+
 	// Profile is what the machine can do, detected again by this apply (novox/hq ADR 0161): the
 	// same shape enrolment sends, so a machine that gained or lost a capability — switched its
 	// network manager — is known at its next push and not at its next enrolment. Absent from a host
@@ -278,6 +287,21 @@ type Held struct {
 	Facts map[string]any `json:"facts,omitempty"`
 }
 
+// A Filter is one place on a machine that refuses traffic, with its owner (novox/hq ADR 0168):
+// the host's own shape, carried as data.
+type Filter struct {
+	Where   string `json:"where"`
+	Owner   string `json:"owner"`
+	Refuses string `json:"refuses"`
+}
+
+// FoundFirewall is the state of a converged machine's found firewall (ADR 0168).
+type FoundFirewall struct {
+	Kind      string `json:"kind"`
+	Active    bool   `json:"active"`
+	RetiredBy string `json:"retired_by,omitempty"`
+}
+
 // A Stray is a container a machine runs that the mesh neither wrote nor holds (ADR 0163).
 type Stray struct {
 	Kind   string `json:"kind"`