WIP: recheck a take's filesystem, follow only the module's branch, count users in an access change, hold the identity until its data is taken (hq ADR 0325 review)

cmd/mesh-controller/asker.go

@@ -892,7 +892,7 @@ func (a *asker) Decided(ctx context.Context, body []byte) error {
 		// A shared folder taken on the operator's warrant (novox/hq ADR 0325 §8): the act is composed again from the
 		// record and held to what the option bound before the engine is asked.
 		outcome, acted = a.decideTake(ctx, *r, act, w)
-		if acted == nil {
+		if acted == nil && !strings.HasPrefix(outcome, "nothing") {
 			outcome = "done: " + outcome
 		}
 	case r.Take != nil:

cmd/mesh-controller/gate.go

@@ -814,11 +814,18 @@ func movesChangingAccesses(ctx context.Context, inv *inventory.Inventory, g *inv
 			out[j.module] = true
 			continue
 		}
-		out[j.module] = !sameAccesses(before.Accesses, target.Accesses)
+		out[j.module] = !sameAccessUse(before, target)
 	}
 	return out
 }
 
+// sameAccessUse says a move leaves a module's accesses as they were, users included (the review of e1c2b744): the
+// same accesses at the same use, and the same containers declaring identity and mounting each — a container that
+// starts or stops running as the module's identity changes who uses the folder.
+func sameAccessUse(a, b catalogue.Manifest) bool {
+	return sameAccesses(a.Accesses, b.Accesses) && catalogue.AccessUsersShape(a) == catalogue.AccessUsersShape(b)
+}
+
 // sameAccesses says two manifests declare the same accesses, at the same use, in any order.
 func sameAccesses(a, b []catalogue.Access) bool {
 	key := func(as []catalogue.Access) string {

cmd/mesh-controller/kept_folders.go

@@ -235,6 +235,24 @@ func (a *asker) decideTake(ctx context.Context, r asked, act conditions.Action,
 	if a.take == nil {
 		return "", errors.New("this controller cannot take a folder on a warrant")
 	}
+	// **The folder must still wait on the filesystem the operator was asked about** (the review of e1c2b744): a take
+	// is about no condition, so nothing else rechecks it. A folder that moved to another filesystem, or no longer
+	// waits for the operator's word, is not taken: the ask is spent, and one for the filesystem it is on now is asked.
+	if a.folders != nil {
+		waiting, err := a.folders(ctx)
+		if err != nil {
+			return "", fmt.Errorf("whether the folder still waits on %s could not be read, so nothing is taken: %w",
+				t.Node, err)
+		}
+		still := false
+		for _, now := range waiting {
+			still = still || now.key() == t.key()
+		}
+		if !still {
+			return "nothing: the folder no longer waits to be kept on the filesystem the operator was asked about " +
+				"(it moved, or was taken or released meanwhile); asked again where it waits now", nil
+		}
+	}
 	by := fmt.Sprintf("approved by %s via %s at %s (ask %s)", byWords(w), viaWords(w),
 		w.At.Local().Format("2006-01-02 15:04"), r.ID)
 	return a.take(ctx, t, r.ID, by)

cmd/mesh-controller/kept_folders_test.go

@@ -404,8 +404,8 @@ func TestAFolderThatMovedIsAskedAboutAgain(t *testing.T) {
 	}
 }
 
-// The mesh's entries left while a disk was away (kind kept-entries), stated before the send, do not hold a delivery
+// The mesh's entries left while a disk was away (kind kept-entries) do not hold a delivery whose move leaves the
-// that did not bring them; stated since, they do — and they may name an access no longer declared.
+// module's accesses as they were — they may name an access no longer declared; one that changes them is held.
 func TestEntriesLeftWhileADiskWasAwayDoNotHoldADeliveryThatDidNotBringThem(t *testing.T) {
 	now := time.Now()
 	since := now.Add(-time.Minute)
@@ -413,15 +413,19 @@ func TestEntriesLeftWhileADiskWasAwayDoNotHoldADeliveryThatDidNotBringThem(t *te
 		Target: moviesAt, State: link.StateUnhealthy, Reason: "the mesh's entries could not be taken out: its disk is away",
 		Since: since.Add(-time.Hour)}
 	f := gateFacts{now: now, waits: accessFacts(), groupsAdded: map[string]bool{"radarr": false},
-		health: map[string]inventory.NodeHealth{"ace": {Node: "ace", HeardAt: now,
+		accessesChanged: map[string]bool{"radarr": false}, health: map[string]inventory.NodeHealth{"ace": {Node: "ace",
-			Resources: []inventory.ResourceHealth{left}}}}
+			HeardAt: now, Resources: []inventory.ResourceHealth{left}}}}
 	if h, why := moduleHealthWord("radarr", "ace", since, f); h != healthPerson || !strings.Contains(why, "access-gone~entries") {
 		t.Fatalf("entries left before the send read %v %q; want carried in a passing verdict", h, why)
 	}
 	left.Since = now
 	f.health["ace"] = inventory.NodeHealth{Node: "ace", HeardAt: now, Resources: []inventory.ResourceHealth{left}}
+	if h, _ := moduleHealthWord("radarr", "ace", since, f); h != healthPerson {
+		t.Fatalf("entries stated since the send by a move that leaves accesses as they were read %v", h)
+	}
+	f.accessesChanged = nil // a move not known changes them
 	if h, _ := moduleHealthWord("radarr", "ace", since, f); h != healthNotYet {
-		t.Fatalf("entries left by this send read %v; want judged unhealthy", h)
+		t.Fatalf("entries of a move not known read %v; want judged unhealthy", h)
 	}
 }
 
@@ -494,3 +498,66 @@ func TestTheEnginesAccessWaitsAndEntriesAreKept(t *testing.T) {
 		t.Fatalf("the listing reads:\n%s", all)
 	}
 }
+
+// Review of e1c2b744: a warrant for a folder on one filesystem never takes it on another. When the warrant comes and
+// the folder no longer waits on the filesystem the ask named, nothing is sent, the ask is spent, and the operator is
+// asked again for the filesystem it is on now.
+func TestAWarrantForOneFilesystemIsNotCarriedOutOnAnother(t *testing.T) {
+	placed := "fs-000000000001"
+	r, taken := takeRig(t, func() map[string]map[string][]waitingFolder {
+		return waitingOn("ace", waitingFolder{module: "radarr", access: "movies", resource: "radarr.access-movies",
+			placed: placed})
+	})
+	ctx := context.Background()
+	if err := r.a.reconcile(ctx); err != nil {
+		t.Fatal(err)
+	}
+	a := takeAsks(r)[0]
+	placed = "fs-0000000000ff" // the folder moved before the operator answered
+	answerWith(t, r, warrantOn(a, "let-the-mesh-keep-it", r.now))
+	if len(*taken) != 0 {
+		t.Fatalf("a warrant for %s was carried out on %s: %v", a.Take.Placed, placed, *taken)
+	}
+	if spent := r.store[a.ID]; spent.State == askOpen || !strings.HasPrefix(spent.Acted, "nothing") {
+		t.Fatalf("the ask after the folder moved: %s, %q", spent.State, spent.Acted)
+	}
+	if err := r.a.reconcile(ctx); err != nil {
+		t.Fatal(err)
+	}
+	var again []asked
+	for _, x := range takeAsks(r) {
+		if x.State == askOpen {
+			again = append(again, x)
+		}
+	}
+	if len(again) != 1 || again[0].Take.Placed != placed {
+		t.Fatalf("not asked again for the filesystem the folder is on now: %+v", again)
+	}
+}
+
+// Review of e1c2b744: a move that changes who uses an access — a container of the module that starts declaring
+// identity — changes the access, so an access the engine cannot judge is not passed uncounted.
+func TestAMoveThatChangesAnAccesssUsersChangesTheAccess(t *testing.T) {
+	before := catalogue.Manifest{Module: "radarr", Accesses: radarrManifest.Accesses, Resources: []map[string]any{
+		{"id": "app", "type": "container", "volumes": []any{"${access:movies}:/movies"}}}}
+	after := catalogue.Manifest{Module: "radarr", Accesses: radarrManifest.Accesses, Resources: []map[string]any{
+		{"id": "app", "type": "container", "identity": map[string]any{"user": "run"},
+			"volumes": []any{"${access:movies}:/movies"}}}}
+	if sameAccessUse(before, after) {
+		t.Fatal("a move that adds identity to the container mounting the access left it the same")
+	}
+	if !sameAccessUse(before, before) {
+		t.Fatal("an unchanged manifest reads changed")
+	}
+	// Entries left while a disk was away, stated before the send, of a move that changes the access: counted.
+	now := time.Now()
+	since := now.Add(-time.Minute)
+	left := inventory.ResourceHealth{Module: "radarr", Resource: "radarr.access-movies~entries", Kind: link.KindKeptEntries,
+		Target: moviesAt, State: link.StateUnhealthy, Since: since.Add(-time.Hour)}
+	f := gateFacts{now: now, waits: accessFacts(), groupsAdded: map[string]bool{"radarr": false},
+		accessesChanged: map[string]bool{"radarr": true}, health: map[string]inventory.NodeHealth{"ace": {Node: "ace",
+			HeardAt: now, Resources: []inventory.ResourceHealth{left}}}}
+	if h, _ := moduleHealthWord("radarr", "ace", since, f); h != healthNotYet {
+		t.Fatalf("entries left before the send by a move that changes the access read %v; want counted", h)
+	}
+}

cmd/mesh-controller/module_health.go

@@ -678,12 +678,13 @@ func moduleHealthWord(module, machine string, since time.Time, f gateFacts) (hea
 			continue
 		}
 		// **The mesh's entries left on a folder whose disk was away are a condition this build found** when its move
-		// leaves the module's accesses as they were, or they were stated before this send (novox/hq ADR 0325 §8): they
+		// leaves the module's accesses and their users as they were (novox/hq ADR 0325 §8): they may name an access no
-		// may name an access no longer declared, they wait for the disk, and a delivery that did not bring them is not
+		// longer declared, they wait for the disk, and a delivery that did not bring them is not held for them — said in
-		// held for them — said in the verdict, as a directory used as found is. Otherwise they are judged unhealthy.
+		// the verdict, as a directory used as found is. A move that changes the accesses is held to them, whenever they
+		// were stated (the review of e1c2b744).
 		changed, known := f.accessesChanged[module]
 		changes := !known || changed
-		if r.Kind == link.KindKeptEntries && r.State == link.StateUnhealthy && (!changes || r.Since.Before(since)) {
+		if r.Kind == link.KindKeptEntries && r.State == link.StateUnhealthy && !changes {
 			leftover = append(leftover, r.Resource)
 			continue
 		}

cmd/mesh-controller/plan.go

@@ -977,7 +977,7 @@ func renderingFor(ctx context.Context, open *stores, node string,
 		return catalogue.Rendering{}, inventory.Node{}, err
 	}
 	// Each module's identity and the folders taken here (novox/hq ADR 0325 §3, §8), to an engine that keeps folders.
-	keepsFolders, identities, keptFolders, err := folderFacts(ctx, inv, node, plan, choosing)
+	keepsFolders, identities, keptFolders, readyFolders, err := folderFacts(ctx, inv, node, plan, choosing)
 	if err != nil {
 		return catalogue.Rendering{}, inventory.Node{}, err
 	}
@@ -987,6 +987,7 @@ func renderingFor(ctx context.Context, open *stores, node string,
 		KeepsFolders:  keepsFolders,
 		Identities:    identities,
 		KeptFolders:   keptFolders,
+		ReadyFolders:  readyFolders,
 		BusMembership: memberships[node],
 		Settings:      settings, Generators: gens, Grants: grants, Needed: needed, Foreseen: foreseen, Ports: ports,
 		Certificate: certificate, Authority: authority, Mesh: private, Names: names,
@@ -1035,10 +1036,10 @@ func engineKeepsFolders(ctx context.Context, inv *inventory.Inventory, node stri
 // (Allocating), as a port is: a question about what would be sent reads what was allocated, and a module that has
 // none yet is composed without one. Nothing is read for an engine that does not keep folders.
 func folderFacts(ctx context.Context, inv *inventory.Inventory, node string, plan catalogue.Resolution,
-	choosing Choosing) (bool, map[string]catalogue.ModuleIdentity, map[string]bool, error) {
+	choosing Choosing) (bool, map[string]catalogue.ModuleIdentity, map[string]bool, map[string]bool, error) {
 	keeps, err := engineKeepsFolders(ctx, inv, node)
 	if err != nil || !keeps {
-		return false, nil, nil, err
+		return false, nil, nil, nil, err
 	}
 	identities := map[string]catalogue.ModuleIdentity{}
 	for _, m := range plan.Modules {
@@ -1053,7 +1054,7 @@ func folderFacts(ctx context.Context, inv *inventory.Inventory, node string, pla
 			id, had, err = inv.IdentityOf(ctx, m.Module)
 		}
 		if err != nil {
-			return false, nil, nil, err
+			return false, nil, nil, nil, err
 		}
 		if had {
 			identities[m.Module] = id
@@ -1061,7 +1062,7 @@ func folderFacts(ctx context.Context, inv *inventory.Inventory, node string, pla
 	}
 	taken, err := inv.KeptFolders(ctx, node)
 	if err != nil {
-		return false, nil, nil, err
+		return false, nil, nil, nil, err
 	}
 	kept := map[string]bool{}
 	for path := range taken {
@@ -1069,9 +1070,17 @@ func folderFacts(ctx context.Context, inv *inventory.Inventory, node string, pla
 	}
 	// **A folder that moved to another filesystem is not taken there until its new warrant** (ADR 0325 §8): the
 	// machine's newest statement names, without a path, the filesystem each folder waiting for the operator is on now.
+	// And every folder the engine says it keeps (its access healthy): one it found empty, or took itself — what, with
+	// a taken one, lets a container switch to its identity (identityHeld).
+	ready := map[string]bool{}
 	if stated, had, err := inv.HealthOf(ctx, node); err != nil {
-		return false, nil, nil, err
+		return false, nil, nil, nil, err
 	} else if had {
+		for _, r := range stated.Resources {
+			if r.Kind == link.KindAccess && r.State == link.StateHealthy && r.Target != "" {
+				ready[filepath.Clean(r.Target)] = true
+			}
+		}
 		for _, r := range stated.Resources {
 			for _, w := range r.Waits {
 				path := filepath.Clean(r.Target)
@@ -1081,7 +1090,7 @@ func folderFacts(ctx context.Context, inv *inventory.Inventory, node string, pla
 			}
 		}
 	}
-	return true, identities, kept, nil
+	return true, identities, kept, ready, nil
 }
 
 // zonesInTheMesh is every zone a module in the mesh declares, where the mesh placed it (novox/hq ADR

internal/catalogue/declaration.go

@@ -257,6 +257,9 @@ type Rendering struct {
 	Identities map[string]ModuleIdentity
 	// KeptFolders is every folder the operator let the mesh keep on this machine (ADR 0325 §8), by its clean path.
 	KeptFolders map[string]bool
+	// ReadyFolders is every folder the engine states it keeps on this machine (its access healthy), by clean path: a
+	// folder it found empty and kept, or took itself. With KeptFolders, what lets a container switch to its identity.
+	ReadyFolders map[string]bool
 }
 
 // RootField is a user resource's field saying the account must never become root without a person
@@ -583,6 +586,9 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			*identities = append(*identities, ident)
 		}
 		mountedByIdentity := dirsMountedByIdentity(m)
+		// Its containers run as it only once every read-write folder they mount is taken (the operator's question on
+		// ADR 0325): until then the identity is allocated, sent and named in the take's users, and not switched to.
+		runsAsIdent := hasIdent && !identityHeld(m, with)
 
 		// What the mesh computes for this module goes FIRST, before the module's own resources.
 		//
@@ -1036,7 +1042,7 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			ownerInto(copied, placed)
 			// And its identity (novox/hq ADR 0325 §2, §3): a container's resolved, or taken out where none is composed;
 			// the owner of a directory its identity's containers mount. After the placement's owner: the identity wins.
-			if err := identityInto(copied, m, ident, hasIdent, mountedByIdentity); err != nil {
+			if err := identityInto(copied, m, ident, runsAsIdent, mountedByIdentity); err != nil {
 				return nil, err
 			}
 			// **After settings, and that is the whole reason it is here.** A module's file

internal/catalogue/module_identity.go

@@ -187,6 +187,24 @@ func volumeSource(v string) string {
 	return v
 }
 
+// AccessUsersShape is who among a module's containers uses which access as the module's identity, in a form that
+// compares: each container declaring identity with how it is told, and the accesses it mounts, sorted. Two manifests
+// with the same shape give their accesses the same container users.
+func AccessUsersShape(m Manifest) string {
+	var out []string
+	for _, r := range m.Resources {
+		v, declares := r[IdentityField]
+		if fmt.Sprint(r["type"]) != "container" || !declares {
+			continue
+		}
+		_, accesses := containerMounts(r)
+		sort.Strings(accesses)
+		out = append(out, fmt.Sprint(r["id"], v, accesses))
+	}
+	sort.Strings(out)
+	return strings.Join(out, "\x01")
+}
+
 // accessMode is the mode an access a container mounts was declared at, by id or by "path:<path>"; "" when the
 // manifest declares no such access.
 func accessMode(m Manifest, ref string) string {
@@ -387,6 +405,49 @@ func identityInto(resource map[string]any, m Manifest, id ModuleIdentity, has bo
 	return nil
 }
 
+// identityHeld says module m's containers are not switched to its identity yet (the operator's question on ADR 0325):
+// a container declaring `identity` mounts a read-write access whose folder is neither taken (KeptFolders) nor kept by
+// the engine (ReadyFolders). Switched before the take adds the identity's entry, the app would run as the new uid and
+// lose write on the operator's existing files; held, it runs as it did (its environment's PUID and PGID), the take's
+// users already name the identity, and the switch comes in the apply after every such folder is taken.
+func identityHeld(m Manifest, with Rendering) bool {
+	_, byID, err := accessesFor(m, with.Settings[m.Module])
+	if err != nil {
+		return true // refused where the module itself is composed; never switched on a guess
+	}
+	for _, r := range m.Resources {
+		if _, declares := r[IdentityField]; !declares || fmt.Sprint(r["type"]) != "container" {
+			continue
+		}
+		_, refs := containerMounts(r)
+		for _, ref := range refs {
+			if accessMode(m, ref) != AccessReadWrite {
+				continue
+			}
+			path := byID[ref]
+			if strings.HasPrefix(ref, "path:") {
+				path = strings.TrimPrefix(ref, "path:")
+			}
+			path = filepath.Clean(path)
+			if path != "." && !with.KeptFolders[path] && !with.ReadyFolders[path] {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// identityContainers is the composed ids of module m's containers that declare `identity`, whether or not it is sent.
+func identityContainers(m Manifest) map[string]bool {
+	out := map[string]bool{}
+	for _, r := range m.Resources {
+		if _, declares := r[IdentityField]; declares && fmt.Sprint(r["type"]) == "container" {
+			out[m.Module+"."+fmt.Sprint(r["id"])] = true
+		}
+	}
+	return out
+}
+
 // dirsMountedByIdentity is the ids of module m's directories one of its containers declaring `identity` mounts.
 func dirsMountedByIdentity(m Manifest) map[string]bool {
 	out := map[string]bool{}
@@ -442,12 +503,13 @@ func (r Resolution) toolsAccount(m Manifest, with Rendering) string {
 // module's tools run as it, each at the access's use (§4: the engine keeps the widest).
 func usersInto(out []map[string]any, owner map[string]string, m Manifest, id ModuleIdentity, has bool, account string,
 	with Rendering) {
+	// The containers that declare identity, whether or not it is sent yet: the take adds the entries of the identity
+	// to come, so they exist before the switch.
+	declaring := identityContainers(m)
 	var containers []map[string]any
 	for _, res := range out {
-		if res["type"] == "container" && owner[fmt.Sprint(res["id"])] == m.Module {
+		if res["type"] == "container" && owner[fmt.Sprint(res["id"])] == m.Module && declaring[fmt.Sprint(res["id"])] && has {
-			if _, declares := res[IdentityField]; declares && has {
+			containers = append(containers, res)
-				containers = append(containers, res)
-			}
 		}
 	}
 	for _, res := range out {

internal/catalogue/module_identity_test.go

@@ -78,7 +78,7 @@ func TestAModuleRunsAsItsIdentityTheSameOnEveryMachine(t *testing.T) {
 	var seen []string
 	for _, node := range []string{"ace", "novox"} {
 		r := Resolution{Node: node, Account: "jochen", Modules: []Manifest{aLibrarian(t), aPlayer(t), theRuntime(t)}}
-		composed := composeFolders(t, r, keepingFolders(identities))
+		composed := composeFolders(t, r, keepingFolders(identities, "/storage/media/movies")) // its read-write folder taken: switched
 		got := byID(composed.Resources)
 
 		app := got["librarian.app"]
@@ -331,3 +331,40 @@ func TestAModuleWithoutIdentityIsWarnedNotRefused(t *testing.T) {
 		t.Error("an identity module was warned rather than refused")
 	}
 }
+
+// A container is not switched to its identity while a read-write folder it mounts holds data the mesh has not taken
+// (the operator's question on ADR 0325): the app would run as the new uid before the take adds its entry, and lose
+// write on the existing files. Its identity is held — no `identity` sent, its directories keep their owner — while
+// the take's users already name the identity, so the entries exist before the switch; once every such folder is
+// taken (or kept by the engine), the identity is sent in one apply.
+func TestAContainerKeepsItsOldIdentityUntilItsDataIsTaken(t *testing.T) {
+	r := Resolution{Node: "ace", Account: "jochen", Modules: []Manifest{aLibrarian(t), theRuntime(t)}}
+	held := byID(composeFolders(t, r, keepingFolders(identities)).Resources)
+	if _, has := held["librarian.app"][IdentityField]; has {
+		t.Fatalf("the container was told its identity while its movies are not taken: %v", held["librarian.app"][IdentityField])
+	}
+	if owner, has := held["librarian.config"]["owner"]; has {
+		t.Fatalf("its directory was given the owner %v while its identity is held", owner)
+	}
+	users, _ := json.Marshal(held["librarian."+AccessID("/storage/media/movies")]["users"])
+	if !strings.Contains(string(users), `"identity":"mesh-librarian","uid":50001`) {
+		t.Fatalf("the access does not name the identity to come, so the take would not add its entry: %s", users)
+	}
+
+	for name, with := range map[string]Rendering{
+		"taken": keepingFolders(identities, "/storage/media/movies"),
+		"kept by the engine": func() Rendering {
+			w := keepingFolders(identities)
+			w.ReadyFolders = map[string]bool{"/storage/media/movies": true}
+			return w
+		}(),
+	} {
+		got := byID(composeFolders(t, r, with).Resources)
+		if _, has := got["librarian.app"][IdentityField]; !has {
+			t.Errorf("%s: the container is not told its identity", name)
+		}
+		if got["librarian.config"]["owner"] != "50001:50001" {
+			t.Errorf("%s: its directory is owned by %v", name, got["librarian.config"]["owner"])
+		}
+	}
+}

internal/inventory/catalogue.go

@@ -970,6 +970,17 @@ func (i *Inventory) judgeSettings(ctx context.Context, nodeName, module string,
 		if aerr != nil {
 			return aerr
 		}
+		if !has {
+			follows, ferr := i.followsABranch(ctx, module)
+			if ferr != nil {
+				return ferr
+			}
+			if !follows {
+				return fmt.Errorf("refused: %s on %s cannot compose with the layer %q — %w; and %s follows no branch "+
+					"(it was registered by hand), so no build of it can be judged ahead of what is registered", module,
+					where, from, err, module)
+			}
+		}
 		if !has || catalogue.JudgeSettings(ahead, layers, adopted) != nil || catalogue.ComposesWith(m, layers, adopted) != nil {
 			return fmt.Errorf("refused: %s on %s cannot compose with the layer %q — %w; nor does the newest build of "+
 				"%s on the branch it follows declare it", module, where, from, err, module)
@@ -990,15 +1001,26 @@ func (i *Inventory) judgeSettings(ctx context.Context, nodeName, module string,
 	return nil
 }
 
+// followsABranch says a module's record names the branch it follows.
+func (i *Inventory) followsABranch(ctx context.Context, module string) (bool, error) {
+	var ref string
+	err := i.store.Pool().QueryRow(ctx, `select coalesce(ref, '') from module where name = $1`, module).Scan(&ref)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return false, nil
+	}
+	return ref != "", err
+}
+
 // NewestManifestOnBranch is the manifest of a module's newest successful build on the branch its record follows
 // (novox/hq issue 575): what the delivery under way brings, before it registers — or the registered one's own, when
-// nothing newer was built. False when no build of the module with a manifest is kept.
+// nothing newer was built. Only a build of that very branch: never one of another branch or of none. False when no
+// such build is kept, and for a module whose record follows no branch (registered by hand).
 func (i *Inventory) NewestManifestOnBranch(ctx context.Context, module string) (catalogue.Manifest, bool, error) {
 	var raw []byte
 	err := i.store.Pool().QueryRow(ctx,
 		`select b.manifest from build b join module m on m.name = b.module
 		  where b.module = $1 and b.failed = '' and b.manifest is not null and b.manifest::text <> 'null'
-		    and (coalesce(m.ref, '') = '' or b.ref = '' or b.ref = m.ref)
+		    and coalesce(m.ref, '') <> '' and b.ref = m.ref
 		  order by b.at desc limit 1`, module).Scan(&raw)
 	if errors.Is(err, pgx.ErrNoRows) {
 		return catalogue.Manifest{}, false, nil

internal/inventory/identities_test.go

@@ -2,6 +2,7 @@ package inventory
 
 import (
 	"encoding/json"
+	"fmt"
 	"strings"
 	"testing"
 
@@ -168,3 +169,56 @@ func TestAPlacementIsJudgedAgainstTheBuildThatBringsTheAccess(t *testing.T) {
 		t.Fatal("a placement no build declares was taken")
 	}
 }
+
+// Review of e1c2b744: only a build of the branch the module's record follows judges a placement ahead of it — never one
+// from another branch, nor one with no branch, and a module registered with no branch is refused as before, saying so.
+func TestOnlyABuildOfTheFollowedBranchJudgesAPlacementAhead(t *testing.T) {
+	inv := fresh(t)
+	ctx := t.Context()
+	if _, err := inv.AddNode(ctx, "ace"); err != nil {
+		t.Fatal(err)
+	}
+	registered := catalogue.Manifest{Module: "importer", Version: "1",
+		Resources: []map[string]any{{"id": "server", "type": "container", "name": "importer", "image": "x"}}}
+	ahead := registered
+	ahead.Accesses = []catalogue.Access{{ID: "movies", Path: "/services/media/movies", Mode: catalogue.AccessReadWrite}}
+	raw, err := json.Marshal(ahead)
+	if err != nil {
+		t.Fatal(err)
+	}
+	placing := map[string]any{catalogue.AccessesSetting: map[string]any{"movies": "/storage/media/movies"}}
+	if err := inv.RegisterModule(ctx, registered, Source{Repository: "https://forge.invalid/media.git", Ref: "main",
+		BuiltFrom: "c0ffee"}); err != nil {
+		t.Fatal(err)
+	}
+	for i, ref := range []string{"feature", ""} {
+		b := aBuild(fmt.Sprintf("elsewhere%d", i), "importer", "")
+		b.Ref, b.Manifest = ref, raw
+		if err := inv.RecordBuild(ctx, b); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := inv.JudgeSettings(ctx, "ace", "importer", placing); err == nil {
+		t.Fatal("a build of another branch, or of none, judged the placement")
+	}
+	// Registered by hand, with no branch: refused, saying why.
+	byHand := registered
+	byHand.Module = "byhand"
+	if err := inv.RegisterModule(ctx, byHand, Source{}); err != nil {
+		t.Fatal(err)
+	}
+	aheadByHand := ahead
+	aheadByHand.Module = "byhand"
+	if raw, err = json.Marshal(aheadByHand); err != nil {
+		t.Fatal(err)
+	}
+	b := aBuild("onmain", "byhand", "")
+	b.Ref, b.Manifest = "main", raw
+	if err := inv.RecordBuild(ctx, b); err != nil {
+		t.Fatal(err)
+	}
+	if err := inv.JudgeSettings(ctx, "ace", "byhand", placing); err == nil ||
+		!strings.Contains(err.Error(), "follows no branch") {
+		t.Fatalf("a module with no branch recorded: %v", err)
+	}
+}

testdata/store-tests

@@ -34,3 +34,4 @@
 ./internal/inventory TestAModuleIsGivenOneIdentityOnceAndNeverRoot
 ./internal/inventory TestAFolderIsTakenOnceUnderAWarrant
 ./internal/inventory TestAPlacementIsJudgedAgainstTheBuildThatBringsTheAccess
+./internal/inventory TestOnlyABuildOfTheFollowedBranchJudgesAPlacementAhead