Promise the vault's intake verbs and let the controller ask them in its own name (issue 675)

The vault takes a value only from the controller, which it knows from the
subject that names its caller. The grant is composed from the records, as
the issued tools' is, so the installer's first user list is unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/broker/controller_buckets_test.go

@@ -96,3 +96,47 @@ func TestWhatTheControllerAskedIsBounded(t *testing.T) {
 		t.Errorf("history %d, age %s, bytes %d", status.History(), status.TTL(), info.Config.MaxBytes)
 	}
 }
+
+// **The controller may ask the vault's intake verbs in its own name** (design 57's V2, issue 675): the vault
+// takes a value only from the controller, which it knows from the subject that names its caller — so the
+// controller is granted that subject for the verbs the vault's holder serves, and no more of the vault's seat.
+// Composed from the records, as the issued tools are: the installer's first user list carries none.
+func TestTheControllerMayAskTheVaultInItsOwnName(t *testing.T) {
+	vault := Declared{Module: "mesh-vault", Holds: []Seat{{Name: "mesh-vault",
+		Serves: []string{"get", "accept", "secret-ask", "issued", "rotate"}}}}
+	users, err := Users(Records{Nodes: []string{"novox"}, Assigned: map[string][]Declared{"novox": {vault}}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	controller := users[0]
+	if strings.Join(controller.AsksTheVault, ",") != "accept,issued,rotate,secret-ask" {
+		t.Fatalf("composed %v", controller.AsksTheVault)
+	}
+	p, err := PermissionsFor(controller)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, verb := range []string{"accept", "secret-ask", "issued", "rotate"} {
+		if !MayPublish(p, CalledSubject("mesh.seat.mesh-vault.tool."+verb, ControllerName)) {
+			t.Errorf("the controller may not ask the vault's %s in its own name", verb)
+		}
+		if MayPublish(p, CalledSubject("mesh.seat.mesh-vault.tool."+verb, "anchor.node-tools")) {
+			t.Errorf("the controller may ask the vault's %s in another's name", verb)
+		}
+	}
+	if MayPublish(p, CalledSubject("mesh.seat.mesh-vault.tool.get", ControllerName)) {
+		t.Error("the controller may ask the vault for a secret: it seals nothing the vault holds")
+	}
+	// A vault that serves none of them yet — the running one — composes no grant, nor does genesis.
+	older := Declared{Module: "mesh-vault", Holds: []Seat{{Name: "mesh-vault", Serves: []string{"get"}}}}
+	users, _ = Users(Records{Nodes: []string{"novox"}, Assigned: map[string][]Declared{"novox": {older}}})
+	if len(users[0].AsksTheVault) != 0 {
+		t.Errorf("a vault serving none composed %v", users[0].AsksTheVault)
+	}
+	genesis, _ := PermissionsFor(Principal{Kind: KindController, PasswordHash: "x"})
+	for _, s := range genesis.Publish {
+		if strings.Contains(s, "mesh-vault") {
+			t.Errorf("the installer's controller may publish %s", s)
+		}
+	}
+}