Merge pull request 'A walk sends the bus's user list alone before its gate, so a new grant is on the bus when the first machine is judged (issue 490)' (#230) from fix/490-grants-reach-the-bus-before-the-gate into main

cmd/mesh-controller/changeplan.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"slices"
 	"sort"
 	"strings"
 
@@ -28,6 +29,14 @@ func changePlanOf(repository, base, head string, r mergeReach, entries []invento
 	for _, e := range entries {
 		byName[e.Manifest.Module] = e
 	}
+	// The machine holding the bus, whose declaration carries every module's grants (novox/hq issue 490).
+	holder := ""
+	for _, e := range entries {
+		if e.Manifest.BusUsers != "" && e.Manifest.ClaimsSeat(catalogue.BrokerSeat) && len(e.On) > 0 {
+			holder = e.On[0]
+		}
+	}
+	var granting []string
 	machines := map[string]*link.MachinePlan{}
 	machine := func(name string) *link.MachinePlan {
 		if machines[name] == nil {
@@ -50,6 +59,10 @@ func changePlanOf(repository, base, head string, r mergeReach, entries []invento
 					machine(on).Receives = append(machine(on).Receives, name)
 				}
 			}
+			if !waits && holder != "" && !(len(e.On) == 1 && e.On[0] == holder) && len(e.On) > 0 &&
+				!slices.Contains(granting, name) {
+				granting = append(granting, name)
+			}
 			switch {
 			case (name == "nats" || catalogue.ProvidesBus(e.Manifest)) && len(e.On) > 0:
 				// Said before the merge (novox/hq issue 336): a new bus build holds every send to the bus's machine
@@ -76,6 +89,13 @@ func changePlanOf(repository, base, head string, r mergeReach, entries []invento
 			}
 		}
 	}
+	if len(granting) > 0 {
+		// Said before the merge (novox/hq issue 490): what the walk does when the change alters the bus's
+		// user list. Whether it does is known only once the builds are registered, so it is said as a rule.
+		p.Steps = append(p.Steps, fmt.Sprintf("%s: if this changes what the bus's user list says (a new tool, "+
+			"subject or user), %s is sent that list alone, every build there kept, before %s is judged on its first "+
+			"machine", grantsStepWord, holder, strings.Join(granting, ", ")))
+	}
 	var names []string
 	for name := range machines {
 		names = append(names, name)
@@ -88,6 +108,10 @@ func changePlanOf(repository, base, head string, r mergeReach, entries []invento
 	return p
 }
 
+// grantsStepWord names the grants step (novox/hq issue 490): the bus's user list sent alone to the machine
+// holding the bus ahead of a walk's gate. Not the bus step, which replaces the bus itself.
+const grantsStepWord = "grants step"
+
 // busUpgradeNeeded is how a change plan says that merging it holds the bus's machine for a person's step.
 const busUpgradeNeeded = "merging this needs a person's bus upgrade"
 

cmd/mesh-controller/gate.go

@@ -1353,6 +1353,10 @@ func gateLine(g *inventory.PlanGate) string {
 	if g.Rollback != "" {
 		line += "; " + g.Rollback
 	}
+	// Before the send it judges (novox/hq issue 490).
+	if said := grantsSaid(g.Grants); said != "" {
+		line += "; " + said
+	}
 	return line
 }
 

cmd/mesh-controller/grants_step_store_test.go

@@ -0,0 +1,198 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/identity"
+	"github.com/novox/mesh-controller/internal/inventory"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// The grants step on a store (novox/hq issue 490): the machine holding the bus is sent its new user list,
+// and nothing else — not the new build of a module it runs, not a module newly assigned there.
+//
+// The restic shape: anchor holds the bus and runs restic at c1, as does laptop; restic's c2 gives it a
+// health tool. The grants step's send to anchor composes restic at c1, carries the user list that grants
+// laptop's node-engine c2's tool, and records that anchor still runs c1. A module newly assigned to anchor
+// makes the step fail, said, rather than install it unjudged.
+func TestTheGrantsStepSendsTheUserListAndNothingElse(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	inv := open.inventory
+	start := time.Now().Add(-time.Hour)
+	build := func(module, commit string, at time.Time, manifest map[string]any) link.BuildResult {
+		manifest["module"], manifest["version"] = module, "1"
+		raw, _ := json.Marshal(manifest)
+		return link.BuildResult{ID: link.NewBuildID(at), Repository: "novox/mesh-catalog", Path: "modules/" + module,
+			On: "anchor", Module: module, Commit: commit, Manifest: raw,
+			Source: &link.SourceOnSeat{Seat: "git", Repository: "novox/mesh-catalog"}}
+	}
+	for _, b := range []link.BuildResult{
+		build("nats", "n1", start, natsFixture()),
+		build("restic", "c1", start.Add(time.Second), resticFixture(false)),
+		build("wallpaper", "w1", start.Add(2*time.Second), wallpaperFixture()),
+	} {
+		if _, _, err := takeIn(ctx, inv, asTheOperator(t, inv, b)); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, a := range [][2]string{{"anchor", "nats"}, {"anchor", "restic"}, {"laptop", "restic"}} {
+		if _, err := inv.Assign(ctx, a[0], a[1]); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, n := range []string{"anchor", "laptop"} {
+		if _, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: "node." + n, Kind: inventory.BusNode, Node: n}); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	wasEpoch := epochForActs
+	epochForActs = func(context.Context) (uint64, error) { return 7, nil }
+	t.Cleanup(func() { epochForActs = wasEpoch })
+
+	// A send to anchor composed as sendToEach composes it: numbered, planned, declared, stamped.
+	compose := func(under context.Context) (catalogue.Resolution, sendable) {
+		t.Helper()
+		numbered, err := allot(under, inv, "anchor")
+		if err != nil {
+			t.Fatal(err)
+		}
+		plan, settings, err := planFor(under, open, "anchor")
+		if err != nil {
+			t.Fatal(err)
+		}
+		gens, err := generators(under, open)
+		if err != nil {
+			t.Fatal(err)
+		}
+		declared, err := declarationWith(under, open, "anchor", plan, settings, gens, Allocating)
+		if err != nil {
+			t.Fatal(err)
+		}
+		numbered.stamp(&declared)
+		return plan, declared
+	}
+	record := func(declared sendable) {
+		t.Helper()
+		body, err := declared.Body()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := recordSent(ctx, inv, "anchor", body, declared.Builds, declared.Epoch,
+			sentRecordOf(ctx, declared)); err != nil {
+			t.Fatal(err)
+		}
+	}
+	// Kept for anchor alone. laptop is never recorded as sent, on purpose: composing anchor resolves laptop
+	// too (who is on the private network), and a step that kept every machine's builds refused anchor's
+	// composition for want of laptop's last send (repo-check of #230 at 0f853e93).
+	kept := keepingEveryBuild(keepingRecorded(ctx), "anchor")
+
+	// What anchor was last sent: everything at the builds of before the merge, as an ordinary send sends it.
+	_, before := compose(keepingRecorded(ctx))
+	record(before)
+	plan, declared := compose(kept)
+	if only, err := grantsOnlyIn(ctx, open, "anchor", plan, declared); err != nil || only != "" {
+		t.Fatalf("with nothing changed, the step reads %q, %v", only, err)
+	}
+
+	// The merge: restic's c2 gives it a health tool.
+	if _, _, err := takeIn(ctx, inv, build("restic", "c2", start.Add(time.Minute),
+		resticFixture(true))); err != nil {
+		t.Fatal(err)
+	}
+
+	// The step's send to anchor: restic as anchor runs it, c1, and the user list granting c2's tool.
+	generation, err := inv.AssignmentGeneration(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	plan, declared = compose(kept)
+	for _, m := range plan.Modules {
+		if m.Module == "restic" && len(m.Tools) > 0 {
+			t.Fatalf("the grants step composed restic's new build on anchor: tools %v", m.Tools)
+		}
+	}
+	if declared.Builds["restic"] != "c1" {
+		t.Fatalf("the step's send records it carries restic %q; want c1, which anchor runs", declared.Builds["restic"])
+	}
+	if !strings.Contains(declared.BusUsers, "mesh.mod.restic.tool.backup_health.laptop") {
+		t.Errorf("the step's declaration does not grant laptop's node-engine restic's new tool:\n%s", declared.BusUsers)
+	}
+	// The generation it carries is the current one (novox/hq issue 234), and the step does not raise it.
+	if declared.composedFrom != generation {
+		t.Errorf("the step's send was composed from generation %d; the mesh is at %d", declared.composedFrom, generation)
+	}
+	// The guard, on the very declaration the send sends: only the user list differs from the last send.
+	if only, err := grantsOnlyIn(ctx, open, "anchor", plan, declared); err != nil || only != "" {
+		t.Fatalf("the step reads as changing more than the user list: %q, %v", only, err)
+	}
+	// And the gate's refusal still reads the step's send: it moves nothing there.
+	if names, err := ungatedIn(kept, open, []string{"anchor"}, ""); err != nil || strings.Join(names, ",") != "anchor" {
+		t.Fatalf("the step's send is refused as a move: %v, %v", names, err)
+	}
+	// Recorded as the send records it: anchor still runs restic c1, its gate still to come there.
+	record(declared)
+	if sent, _, err := inv.SentBuilds(ctx, "anchor"); err != nil || sent["restic"] != "c1" {
+		t.Fatalf("after the step anchor reads as sent restic %q (%v); want c1", sent["restic"], err)
+	}
+	if after, err := inv.AssignmentGeneration(ctx); err != nil || after != generation {
+		t.Fatalf("the step moved the assignment generation from %d to %d (%v)", generation, after, err)
+	}
+
+	// A module newly assigned to anchor: the step would install it, unjudged, so it is refused unsent.
+	if _, err := inv.Assign(ctx, "anchor", "wallpaper"); err != nil {
+		t.Fatal(err)
+	}
+	plan, declared = compose(kept)
+	only, err := grantsOnlyIn(ctx, open, "anchor", plan, declared)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(only, "wallpaper newly assigned") || !strings.Contains(only, "+wallpaper") {
+		t.Fatalf("a new assignment on the bus's machine reads %q; want the step refused, naming it", only)
+	}
+	// And the send itself refuses it, unsent: judged where it is composed, before the bus is dialled.
+	identity.ForTest(t)
+	if _, err := sendToEach(kept, open, []string{"anchor"}); !errors.Is(err, errNotGrantsOnly) ||
+		!strings.Contains(err.Error(), "wallpaper") {
+		t.Fatalf("the grants step's send of a new assignment was not refused by the send: %v", err)
+	}
+}
+
+// fixtureImage is the image every fixture container of the grants step's tests runs.
+var fixtureImage = "registry.invalid:5000/restic/backup@sha256:" + strings.Repeat("b", 64)
+
+// resticFixture is restic's manifest in the shape of mesh-catalog #210: at c2 (withTool) its backup judged by
+// its new tool `backup_health`, beside a check of another kind it does not run itself — a tool check alone
+// is refused (ADR 0227 rule 8, ADR 0240 rule 2) — and at c1 neither.
+func resticFixture(withTool bool) map[string]any {
+	backup := map[string]any{"id": "backup", "type": "container", "name": "restic-backup", "image": fixtureImage}
+	measure := map[string]any{"id": "measure", "type": "container", "name": "restic-measure", "image": fixtureImage}
+	m := map[string]any{"resources": []any{backup, measure}}
+	if withTool {
+		backup["health"] = map[string]any{"kind": catalogue.HealthTool, "tool": "backup_health"}
+		measure["health"] = map[string]any{"kind": "runtime"}
+		m["tools"] = []string{"backup_health"}
+	}
+	return m
+}
+
+// natsFixture is the bus's module: it holds mesh-broker and is sent the user list.
+func natsFixture() map[string]any {
+	return map[string]any{"bus-users": "/var/lib/nats-module/conf/accounts.conf",
+		"claims": []any{map[string]any{"name": catalogue.BrokerSeat, "scope": catalogue.ScopeMesh}}}
+}
+
+// wallpaperFixture is a module the bus's machine is newly assigned.
+func wallpaperFixture() map[string]any {
+	return map[string]any{"resources": []any{
+		map[string]any{"id": "paper", "type": "container", "name": "wallpaper", "image": fixtureImage}}}
+}

cmd/mesh-controller/grants_step_test.go

@@ -0,0 +1,226 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/inventory"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// The grants reach the bus before the gate (novox/hq issue 490).
+//
+// On 2026-10-11 a merge gave restic, assigned to every machine, a new health tool. Its walk sent restic to
+// its first machine and judged it there; that machine's node-engine asked the new tool and the bus refused
+// it, because the grant was in the bus's user list, which only the machine holding the bus carries — and
+// that machine runs restic too, so it was left out of the send while restic's new build waited there for
+// the very gate that could not pass. A person pushed it by hand, carrying restic's new build there unjudged.
+
+// aSend is one send the walk made: to which machines, and whether every build there was kept.
+type aSend struct {
+	names    []string
+	keepsAll bool
+	judged   []string
+}
+
+// sendsRecorded replaces the walk's send and the reading of the bus's user list for one test: the machine
+// holding the bus is novox, and its list is behind as behind says.
+func sendsRecorded(t *testing.T, holder string, behind bool, refuse error) *[]aSend {
+	t.Helper()
+	var sends []aSend
+	wasSend, wasBehind := sendRollout, brokerBehindOf
+	t.Cleanup(func() { sendRollout, brokerBehindOf = wasSend, wasBehind })
+	brokerBehindOf = func(_ context.Context, _ *stores, names []string) (string, bool, error) {
+		if slices.Contains(names, holder) {
+			return holder, false, nil
+		}
+		return holder, behind, nil
+	}
+	sendRollout = func(ctx context.Context, _ *stores, names []string) ([]string, error) {
+		s := aSend{names: append([]string(nil), names...), keepsAll: len(names) == 1 && everyBuildKept(ctx, names[0])}
+		for n := range scopeOf(ctx).judged {
+			s.judged = append(s.judged, n)
+		}
+		sends = append(sends, s)
+		if refuse != nil && s.keepsAll {
+			return nil, refuse
+		}
+		return names, nil
+	}
+	return &sends
+}
+
+// The restic shape: a new tool on a module on every machine, its first machine ace, the bus on novox.
+func TestAWalkSendsTheGrantsToTheBusBeforeTheFirstMachineIsJudged(t *testing.T) {
+	sends := sendsRecorded(t, "novox", true, nil)
+	sent, grants, err := sendJudged(t.Context(), nil, "ace")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(*sends) != 2 {
+		t.Fatalf("the walk made %d send(s), want the grants step and then the first machine: %+v", len(*sends), *sends)
+	}
+	first, then := (*sends)[0], (*sends)[1]
+	if strings.Join(first.names, ",") != "novox" || !first.keepsAll || len(first.judged) != 0 {
+		t.Errorf("the first send is %+v, want novox alone, every build there kept, judging nothing", first)
+	}
+	if strings.Join(then.names, ",") != "ace" || then.keepsAll || strings.Join(then.judged, ",") != "ace" {
+		t.Errorf("the second send is %+v, want ace, judged", then)
+	}
+	if strings.Join(sent, ",") != "ace" {
+		t.Errorf("the gate's machines are %v, want ace alone: the bus's machine is not judged", sent)
+	}
+	if grants == nil || grants.Node != "novox" || grants.At == nil || grants.Failed != "" {
+		t.Fatalf("the gate keeps %+v as its grants step", grants)
+	}
+	line := gateLine(&inventory.PlanGate{Machines: sent, Grants: grants})
+	if !strings.Contains(line, "grants step: novox sent the bus's user list first, its builds kept") {
+		t.Errorf("plans says the gate as %q", line)
+	}
+}
+
+// Nothing more when there is nothing to carry: the list unchanged, or the first machine holds the bus.
+func TestAWalkTakesNoGrantsStepWhenTheListIsAlreadyThere(t *testing.T) {
+	for _, c := range []struct {
+		name   string
+		node   string
+		behind bool
+	}{{"the list unchanged", "ace", false}, {"the first machine holds the bus", "novox", true}} {
+		t.Run(c.name, func(t *testing.T) {
+			sends := sendsRecorded(t, "novox", c.behind, nil)
+			_, grants, err := sendJudged(t.Context(), nil, c.node)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(*sends) != 1 || (*sends)[0].keepsAll || grants != nil {
+				t.Errorf("the walk made %+v with grants %+v, want the judged send alone", *sends, grants)
+			}
+		})
+	}
+}
+
+// A grants step that cannot be sent is said on the gate, and the walk goes on as it did before.
+func TestAGrantsStepThatFailsIsSaidAndTheSendGoesOn(t *testing.T) {
+	sends := sendsRecorded(t, "novox", true, errors.New("a bus upgrade waits for a person"))
+	sent, grants, err := sendJudged(t.Context(), nil, "ace")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.Join(sent, ",") != "ace" || len(*sends) != 2 {
+		t.Errorf("the walk made %+v", *sends)
+	}
+	if grants == nil || grants.Failed == "" || grants.At != nil {
+		t.Fatalf("the gate keeps %+v", grants)
+	}
+	if line := gateLine(&inventory.PlanGate{Machines: sent, Grants: grants}); !strings.Contains(line,
+		"grants step to novox FAILED, sent without it: a bus upgrade waits for a person") {
+		t.Errorf("plans says the gate as %q", line)
+	}
+}
+
+// A step whose send would change more than the user list is refused unsent by the send (sendToEach): the
+// gate says it FAILED with what differed, and the walk goes on.
+func TestAGrantsStepThatWouldCarryMoreIsNotSent(t *testing.T) {
+	refusal := fmt.Errorf("%w: its send would change more than the bus's user list: -postgres.login-n8n", errNotGrantsOnly)
+	sends := sendsRecorded(t, "novox", true, refusal)
+	sent, grants, err := sendJudged(t.Context(), nil, "ace")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.Join(sent, ",") != "ace" || len(*sends) != 2 {
+		t.Errorf("the walk made %+v, want the refused step and then ace's judged send", *sends)
+	}
+	if grants == nil || grants.At != nil || !strings.Contains(grants.Failed, "-postgres.login-n8n") {
+		t.Fatalf("the gate keeps %+v", grants)
+	}
+}
+
+// The step's exemption is the list's content alone: its path or mode moving is a change like any other.
+func TestOnlyTheUserListsContentIsExempt(t *testing.T) {
+	list := "nats.bus-users"
+	file := func(fields map[string]any) sentResource {
+		r := map[string]any{"id": list, "type": "file", "path": "/conf/accounts.conf", "mode": "0600", "content": "a"}
+		for k, v := range fields {
+			r[k] = v
+		}
+		body, _ := json.Marshal(map[string]any{"resources": []any{r}})
+		s, err := summarize(body)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return s[0]
+	}
+	was := file(nil)
+	if other := otherThanTheList(diffSent([]sentResource{was}, []sentResource{file(map[string]any{"content": "b"})}), list); len(other) != 0 {
+		t.Errorf("the list's new content reads as more: %v", other)
+	}
+	for _, f := range []map[string]any{{"mode": "0644"}, {"path": "/elsewhere"}, {"content": "b", "owner": "nats"}} {
+		other := otherThanTheList(diffSent([]sentResource{was}, []sentResource{file(f)}), list)
+		if len(other) != 1 || !strings.HasPrefix(other[0], "~"+list) {
+			t.Errorf("the list's resource changed by %v reads %v; want it refused", f, other)
+		}
+	}
+}
+
+// The step keeps the builds of the machine it sends alone: the others its composition resolves are composed
+// as any send composes them.
+func TestTheGrantsStepKeepsOneMachinesBuilds(t *testing.T) {
+	ctx := keepingEveryBuild(t.Context(), "novox")
+	if !everyBuildKept(ctx, "novox") || everyBuildKept(ctx, "ace") || everyBuildKept(t.Context(), "novox") {
+		t.Error("the grants step keeps the builds of a machine it does not send")
+	}
+}
+
+// The store test's manifests are manifests the controller takes in: checked here, where no store is needed,
+// so a fixture the module rules refuse fails before the store test is run (repo-check of #230 at 325575b2).
+func TestTheGrantsStepFixturesAreManifests(t *testing.T) {
+	for name, m := range map[string]map[string]any{"nats": natsFixture(), "restic-c1": resticFixture(false),
+		"restic-c2": resticFixture(true), "wallpaper": wallpaperFixture()} {
+		m["module"], m["version"] = strings.SplitN(name, "-", 2)[0], "1"
+		raw, err := json.Marshal(m)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := catalogue.ParseManifest(raw); err != nil {
+			t.Errorf("%s: %v", name, err)
+		}
+	}
+}
+
+// The delivery plan says the step before the merge.
+func TestAChangePlanSaysTheGrantsStep(t *testing.T) {
+	const catalogue_ = "http://forge.internal:20000/novox/mesh-catalog.git"
+	entry := func(name string, on ...string) inventory.Entry {
+		e := fromRepo(name, catalogue_, "modules/"+name)
+		e.Source.BuiltFrom = "old"
+		e.On = on
+		return e
+	}
+	nats := entry("nats", "novox")
+	nats.Manifest.BusUsers = "/etc/nats/users.conf"
+	nats.Manifest.Claims = []catalogue.Claim{{Name: catalogue.BrokerSeat, Scope: catalogue.ScopeMesh}}
+	restic := entry("restic", "ace", "novox", "shanks")
+	only := entry("bus-tools", "novox")
+	entries := []inventory.Entry{nats, restic, only}
+	rollsOut := func(string) (inventory.Upgrade, bool) { return inventory.Upgrade{RollOut: true}, true }
+	plan := func(paths ...string) link.ChangePlan {
+		m := link.SourceMoved{Owner: "novox", Repo: "mesh-catalog", Base: "main", Commit: "head", Paths: paths}
+		return changePlanOf("novox/mesh-catalog", "main", "head", reachOfMerge(m, entries, nil, nil), entries, rollsOut)
+	}
+
+	text := planText(plan("modules/restic/module.json"))
+	if !strings.Contains(text, "grants step: if this changes what the bus's user list says (a new tool, subject or "+
+		"user), novox is sent that list alone, every build there kept, before restic is judged on its first machine") {
+		t.Errorf("the change plan does not say the grants step:\n%s", text)
+	}
+	// A module only on the bus's machine goes there with the list in its own send: no step of its own.
+	if text := planText(plan("modules/bus-tools/module.json")); strings.Contains(text, "grants step") {
+		t.Errorf("a module on the bus's machine alone reads:\n%s", text)
+	}
+}

cmd/mesh-controller/issue352_test.go

@@ -69,7 +69,7 @@ func TestAPlansFirstSendWaitsForAReleaseJudgingTheModuleThere(t *testing.T) {
 	b := aBacklog(t)
 	ctx := t.Context()
 	advancePlans(ctx, b.open) // the release judges app c2 on anchor
-	_, _, err := gatedSend(ctx, b.open, "anchor", []inventory.CarriedMove{{Module: "app", Node: "anchor", From: "c2", To: "c3", Build: "build-app-c3"}})
+	_, _, _, err := gatedSend(ctx, b.open, "anchor", []inventory.CarriedMove{{Module: "app", Node: "anchor", From: "c2", To: "c3", Build: "build-app-c3"}})
 	if !errors.Is(err, errWalkedElsewhere) || !strings.Contains(err.Error(), "release-") {
 		t.Fatalf("a newer build of a judged module was sent under the release's gate: %v", err)
 	}

cmd/mesh-controller/push.go

@@ -1236,6 +1236,17 @@ func sendToEach(ctx context.Context, open *stores, names []string) ([]string, er
 			continue
 		}
 		numbered.stamp(&declared)
+		// **The grants step sends the user list and nothing else** (novox/hq issue 490): judged on this very
+		// declaration, the one sent, so nothing composed between a check and the send can slip through.
+		if everyBuildKept(ctx, name) {
+			other, err := grantsOnlyIn(ctx, open, name, plan, declared)
+			if err != nil {
+				return nil, err
+			}
+			if other != "" {
+				return nil, fmt.Errorf("%w: %s", errNotGrantsOnly, other)
+			}
+		}
 		reportLeftOut(name, declared)
 		sending = append(sending, readyNode{name, declared})
 	}

cmd/mesh-controller/recorded_kept.go

@@ -61,20 +61,57 @@ func keptExcept(ctx context.Context) (map[string]bool, bool) {
 	return skip, on
 }
 
+type keepEveryBuildKey struct{}
+
+// keepingEveryBuild is a context whose sends compose every module of one machine — recorded or rolling out —
+// at the build that machine was last sent (novox/hq issue 490): the grants step, which sends the machine
+// holding the bus its new user list and nothing of any module's new code. That code waits there for a gate
+// like any other move; the list must not, or the first machine's gate is judged against a bus that refuses
+// what the change newly grants.
+//
+// **That machine alone.** Composing one machine resolves the others too — who is on the private network,
+// who answers a requirement — on the same context, and those are no part of the step's send: they are
+// composed as any send composes them. Kept for every machine, a machine whose last send is not known
+// refused the bus's machine's composition.
+func keepingEveryBuild(ctx context.Context, node string) context.Context {
+	return context.WithValue(ctx, keepEveryBuildKey{}, node)
+}
+
+// everyBuildKept is whether this context keeps every module of this machine at the build it runs.
+func everyBuildKept(ctx context.Context, node string) bool {
+	on, _ := ctx.Value(keepEveryBuildKey{}).(string)
+	return on != "" && on == node
+}
+
 // recordedKept is, for a send under keepingRecorded, every recorded module the machine was last sent a
 // build of that the mesh's build is not identical to: module → the commit it keeps. Nil when the context
 // keeps nothing, or when what the machine was last sent is not known (it is then held whole elsewhere —
 // ADR 0221).
+//
+// Under keepingEveryBuild, every module the machine was sent is kept, whatever its policy (novox/hq issue
+// 490), and a machine whose last send is not known refuses the send: there is nothing to keep it at, and
+// composing the mesh's builds would be the very move the grants step must not make.
 func recordedKept(ctx context.Context, open *stores, node string) (map[string]string, error) {
+	every := everyBuildKept(ctx, node)
 	skip, on := keptExcept(ctx)
-	if !on {
+	if !on && !every {
 		return nil, nil
 	}
+	if every {
+		skip = nil
+	}
 	inv := open.inventory
 	sent, known, err := inv.SentBuilds(ctx, node)
-	if err != nil || !known {
+	if err != nil {
 		return nil, err
 	}
+	if !known {
+		if every {
+			return nil, fmt.Errorf("what %s was last sent is not known, so the bus's user list cannot be sent "+
+				"there alone with every build kept (novox/hq issue 490)", node)
+		}
+		return nil, nil
+	}
 	current, err := inv.CurrentBuilds(ctx)
 	if err != nil {
 		return nil, err
@@ -83,7 +120,7 @@ func recordedKept(ctx context.Context, open *stores, node string) (map[string]st
 	out := map[string]string{}
 	for m, was := range sent {
 		now, held := current[m]
-		if !held || now.RollOut || skip[m] || was == "" || sameCommit(was, now.Commit) {
+		if !held || (now.RollOut && !every) || skip[m] || was == "" || sameCommit(was, now.Commit) {
 			continue
 		}
 		if f == nil {
@@ -118,6 +155,10 @@ func keepRecorded(ctx context.Context, open *stores, node string, shelf map[stri
 		if err != nil {
 			return nil, err
 		}
+		if !found && everyBuildKept(ctx, node) {
+			return nil, fmt.Errorf("%s runs %s's build %s, which the build records no longer hold: the bus's user "+
+				"list cannot be sent there alone with it kept (novox/hq issue 490)", node, m, short(kept[m]))
+		}
 		if !found {
 			return nil, fmt.Errorf("%s records rather than rolls out, and %s runs its build %s, which the build "+
 				"records no longer hold: this send cannot keep it and does not move it — `push %s` sends the new "+

cmd/mesh-controller/release.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"flag"
 	"fmt"
@@ -253,8 +254,19 @@ func ungatedIn(ctx context.Context, open *stores, names []string, addedHolder st
 		if err != nil {
 			return nil, err
 		}
+		// The grants step composes every module at the build its machine was last sent (novox/hq issue 490):
+		// a move it keeps is not made. Read, not assumed, so a move it could not keep is still refused here.
+		var keeps map[string]string
+		if everyBuildKept(ctx, n) {
+			if keeps, err = recordedKept(ctx, open, n); err != nil {
+				return nil, err
+			}
+		}
 		var waiting []string
 		for _, mv := range moves {
+			if was, kept := keeps[mv.Module]; kept && sameCommit(was, mv.From) {
+				continue
+			}
 			if !scope.judged[n] && !scope.modules[mv.Module] {
 				waiting = append(waiting, fmt.Sprintf("%s %s → %s", mv.Module, short(mv.From), short(mv.To)))
 			}
@@ -283,15 +295,18 @@ func ungatedIn(ctx context.Context, open *stores, names []string, addedHolder st
 // owns are the moves the send exists for — every module of a plan's tier whose first machine this is, in
 // one send (novox/hq issue 281): a send carries the machine's whole declaration (ADR 0221), so a send per
 // module was the same declaration sent again and again, each one setting aside the one before.
-func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.CarriedMove) ([]inventory.CarriedMove, []string, error) {
+//
+// And the grants step first, when the send changes what the bus's user list must say (novox/hq issue 490):
+// answered for the gate to keep, nil when there was none.
+func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.CarriedMove) ([]inventory.CarriedMove, []string, *inventory.GrantsStep, error) {
 	inv := open.inventory
 	f, err := readMoveFacts(ctx, inv)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	moves, err := machineMoves(ctx, open, f, node, true)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	own := func(module string) bool {
 		return slices.ContainsFunc(owns, func(o inventory.CarriedMove) bool { return o.Module == module })
@@ -301,7 +316,7 @@ func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.
 			continue
 		}
 		if id := f.walkedBy(mv.Module, node, mv.To); id != "" {
-			return nil, nil, fmt.Errorf("%w: %s's build %s waits on %s, which %s is walking", errWalkedElsewhere,
+			return nil, nil, nil, fmt.Errorf("%w: %s's build %s waits on %s, which %s is walking", errWalkedElsewhere,
 				mv.Module, short(mv.To), node, id)
 		}
 	}
@@ -309,7 +324,7 @@ func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.
 	// plan, or a release, on this machine is not crossed with a newer build; this send waits for its gate.
 	for _, o := range owns {
 		if id := f.walkedBy(o.Module, node, o.To); id != "" {
-			return nil, nil, fmt.Errorf("%w: %s's build %s waits on %s, which %s is walking", errWalkedElsewhere,
+			return nil, nil, nil, fmt.Errorf("%w: %s's build %s waits on %s, which %s is walking", errWalkedElsewhere,
 				o.Module, short(o.To), node, id)
 		}
 	}
@@ -323,22 +338,22 @@ func gatedSend(ctx context.Context, open *stores, node string, owns []inventory.
 		}
 	}
 	if len(moves) == 0 && len(owns) == 0 {
-		return nil, nil, nil
+		return nil, nil, nil, nil
 	}
 	for i := range moves {
 		if moves[i].Build == "" {
 			if moves[i].Build, err = inv.BuildOf(ctx, moves[i].Module, moves[i].To); err != nil {
-				return nil, nil, err
+				return nil, nil, nil, err
 			}
 		}
 	}
 	sort.Slice(moves, func(i, j int) bool { return moves[i].Module < moves[j].Module })
 	sayRecreations(ctx, open, moves)
-	sent, err := sendRollout(withScope(ctx, sendScope{judged: map[string]bool{node: true}}), open, []string{node})
+	sent, grants, err := sendJudged(ctx, open, node)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
-	return moves, sent, nil
+	return moves, sent, grants, nil
 }
 
 // passCarried keeps a pass as the verdict of every build the gate judged beside its own module.
@@ -674,7 +689,7 @@ func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool,
 				r.Next++
 				continue
 			}
-			moves, sent, err := gatedSend(ctx, open, node, nil)
+			moves, sent, grants, err := gatedSend(ctx, open, node, nil)
 			if errors.Is(err, errWalkedElsewhere) {
 				note := fmt.Sprintf("waiting before %s: %v", node, err)
 				changed := p.Note != note
@@ -689,8 +704,12 @@ func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool,
 				r.Next++
 				continue
 			}
-			r.Gate = &inventory.PlanGate{Machines: sent, Since: &now, Carried: moves, Sent: sentNow(ctx, open.inventory, sent)}
+			r.Gate = &inventory.PlanGate{Machines: sent, Since: &now, Carried: moves, Sent: sentNow(ctx, open.inventory, sent),
+				Grants: grants}
 			p.Note = fmt.Sprintf("sent %s %d build(s) that waited for a gate; judging them there", node, len(moves))
+			if said := grantsSaid(grants); said != "" {
+				p.Note += "; " + said
+			}
 			if said := recreationsSaid(moves); said != "" {
 				p.Note += "; " + said
 			}
@@ -916,3 +935,162 @@ func recreationsSaid(moves []inventory.CarriedMove) string {
 	}
 	return strings.Join(said, "; ")
 }
+
+// The grants step (novox/hq issue 490).
+//
+// The bus's user list — every module's grants, composed mesh-wide from the catalogue — travels only in the
+// declaration of the machine holding the bus. A send to any other machine that changed it put that machine
+// first (issue 249), unless a build waited there for a gate: then ungatedIn left it out, and said so. On
+// 2026-10-11 a merge gave restic a new health tool; its walk sent restic to its first machine and judged it
+// there, the machine's node-engine asked the tool and the bus refused it ("this host's grant does not name
+// …"), because the machine holding the bus also runs restic, whose new build waited for that very gate. The
+// gate could not pass; a person pushed the bus's machine by hand, which carried restic's new build there
+// unjudged.
+//
+// So before a gated send, when the user list composed now is not the one the machine holding the bus was
+// last sent, that machine is sent its declaration with **every build kept at the one it runs**: the new
+// list, and nothing of any module's new code. Said on the gate (`plans`), and, when it cannot be sent, said
+// with why and passed over: the send goes on as it did before, and its gate says what it finds.
+
+// brokerBehindOf is brokerBehind: a variable so a test of the walk needs no store.
+var brokerBehindOf = brokerBehind
+
+// grantsStep sends the machine holding the bus its user list alone, ahead of a gated send to node, when the
+// list changed; answers what it did, or nil when there was nothing to send.
+func grantsStep(ctx context.Context, open *stores, node string) *inventory.GrantsStep {
+	holder, behind, err := brokerBehindOf(ctx, open, []string{node})
+	if err != nil {
+		fmt.Printf("grants step before %s: whether the bus's user list changed could not be read: %v\n", node, err)
+		return &inventory.GrantsStep{Node: "the machine holding the bus", Failed: err.Error()}
+	}
+	if holder == "" || holder == node || !behind {
+		// No bus with a user list, the gate's own machine holds it (its send carries the list first), or the
+		// list is the one already sent.
+		return nil
+	}
+	if _, err := sendRollout(keepingEveryBuild(withScope(ctx, sendScope{}), holder), open, []string{holder}); err != nil {
+		fmt.Printf("grants step: the bus's user list could not be sent to %s ahead of %s, which is sent without "+
+			"it — the bus may refuse what the send newly grants: %v\n", holder, node, err)
+		return &inventory.GrantsStep{Node: holder, Failed: err.Error()}
+	}
+	now := time.Now().UTC()
+	fmt.Printf("grants step: %s sent the bus's user list alone, every build there kept, before %s is judged\n",
+		holder, node)
+	return &inventory.GrantsStep{Node: holder, At: &now}
+}
+
+// errNotGrantsOnly is a grants step refused unsent: its declaration would change more than the user list.
+var errNotGrantsOnly = errors.New("the grants step would change more than the bus's user list, and is not sent")
+
+// grantsOnlyIn is what a grants step's declaration, composed for sending, would change on the machine holding
+// the bus besides its user list, against what it was last sent (novox/hq issue 490); empty when nothing else.
+// Judged by sendToEach on the very declaration it then sends — one composition, judged, then sent or refused
+// unsent. Kept builds are not the whole of a declaration: a new assignment, a settings change, an assignment
+// taken away, a provision's logins are composed as the mesh holds them now, and a step that carried any of
+// it would be the unjudged change this step exists to avoid. Compared resource by resource with the summary
+// the last send kept (ADR 0217): exact, rather than a list of the cases that can differ. A module there that
+// was never sent is a new assignment, refused whatever its resources.
+func grantsOnlyIn(ctx context.Context, open *stores, holder string, plan catalogue.Resolution, declared sendable) (string, error) {
+	inv := open.inventory
+	sent, known, err := inv.SentBuilds(ctx, holder)
+	if err != nil {
+		return "", err
+	}
+	if !known {
+		return fmt.Sprintf("what %s was last sent is not known", holder), nil
+	}
+	var other []string
+	listID := ""
+	for _, m := range plan.Modules {
+		if _, was := sent[m.Module]; !was {
+			other = append(other, m.Module+" newly assigned")
+		}
+		if m.BusUsers != "" && m.ClaimsSeat(catalogue.BrokerSeat) {
+			listID = m.Module + "." + catalogue.BusUsersID()
+		}
+	}
+	var facts *moveFacts
+	for m, was := range sent {
+		now, carried := declared.Builds[m]
+		if !carried || sameCommit(now, was) {
+			continue
+		}
+		if facts == nil {
+			f, err := readMoveFacts(ctx, inv)
+			if err != nil {
+				return "", err
+			}
+			facts = &f
+		}
+		if !facts.identical(m, was, now) {
+			other = append(other, fmt.Sprintf("%s %s → %s", m, short(was), short(now)))
+		}
+	}
+	for _, f := range declared.foreseen {
+		other = append(other, f+" would be minted")
+	}
+	body, err := declared.Body()
+	if err != nil {
+		return "", err
+	}
+	after, err := summarize(body)
+	if err != nil {
+		return "", err
+	}
+	prev, err := inv.SentSummary(ctx, holder)
+	if err != nil {
+		return "", err
+	}
+	if len(prev) == 0 {
+		return fmt.Sprintf("what %s was last sent is not kept for comparison", holder), nil
+	}
+	var before []sentResource
+	if err := json.Unmarshal(prev, &before); err != nil {
+		return "", fmt.Errorf("what %s was last sent is kept in a form this version does not read: %w", holder, err)
+	}
+	other = append(other, otherThanTheList(diffSent(before, after), listID)...)
+	sort.Strings(other)
+	if len(other) == 0 {
+		return "", nil
+	}
+	return "its send would change more than the bus's user list: " + strings.Join(other, "; "), nil
+}
+
+// otherThanTheList is what a diff against the last send changes besides the user list's content: every
+// resource added, removed or changed, but the list's own resource when its content is all that changed —
+// its path, mode and every other field must be as last sent (novox/hq issue 490).
+func otherThanTheList(d sentDiff, listID string) []string {
+	var other []string
+	for _, id := range d.Added {
+		other = append(other, "+"+id)
+	}
+	for _, id := range d.Removed {
+		other = append(other, "-"+id)
+	}
+	for _, c := range d.Changed {
+		if c.ID == listID && len(c.Fields) == 1 && c.Fields[0] == "content" {
+			continue
+		}
+		other = append(other, fmt.Sprintf("~%s (%s)", c.ID, strings.Join(c.Fields, ", ")))
+	}
+	return other
+}
+
+// sendJudged is a gated send's sends: the grants step when the user list changed, then the machine judged.
+func sendJudged(ctx context.Context, open *stores, node string) ([]string, *inventory.GrantsStep, error) {
+	grants := grantsStep(ctx, open, node)
+	sent, err := sendRollout(withScope(ctx, sendScope{judged: map[string]bool{node: true}}), open, []string{node})
+	return sent, grants, err
+}
+
+// grantsSaid is a grants step as `plans` and a walk's note say it.
+func grantsSaid(g *inventory.GrantsStep) string {
+	switch {
+	case g == nil:
+		return ""
+	case g.Failed != "":
+		return fmt.Sprintf(grantsStepWord+" to %s FAILED, sent without it: %s", g.Node, g.Failed)
+	default:
+		return fmt.Sprintf(grantsStepWord+": %s sent the bus's user list first, its builds kept", g.Node)
+	}
+}

cmd/mesh-controller/release_plan.go

@@ -971,7 +971,7 @@ func firstSend(ctx context.Context, open *stores, p *inventory.Plan, node string
 	}
 	// A gated send (ADR 0236): everything waiting on the machine goes with the tier, and the gate judges
 	// all of it there.
-	carried, sent, err := gatedSend(ctx, open, node, owns)
+	carried, sent, grants, err := gatedSend(ctx, open, node, owns)
 	if err != nil {
 		return err
 	}
@@ -992,6 +992,7 @@ func firstSend(ctx context.Context, open *stores, p *inventory.Plan, node string
 		s.GatedBy = ""
 		if m == lead {
 			s.Gate.Carried = carried
+			s.Gate.Grants = grants
 		} else {
 			s.GatedBy = lead
 		}
@@ -1001,6 +1002,10 @@ func firstSend(ctx context.Context, open *stores, p *inventory.Plan, node string
 		strings.Join(sent, ", "))
 	fmt.Printf("%s: tier %d built; sent %d module(s) to %s first in one send (%s), the rest once its gate passes\n",
 		p.ID, p.Tier, len(modules), strings.Join(sent, ", "), strings.Join(modules, ", "))
+	// The grants step taken before it (novox/hq issue 490), said with it.
+	if said := grantsSaid(grants); said != "" {
+		p.Note += "; " + said
+	}
 	// What the send recreates, said with it (novox/hq ADR 0245).
 	if said := recreationsSaid(carried); said != "" {
 		p.Note += "; " + said