A tool's grant covers the machine-addressed subject, and a credential names the seats its module claims (hq ADR 0159)

`invokes: [<module>.<tool>]` now grants `mesh.mod.<module>.tool.<tool>` and the same with the
machine as its last token, which is how a call reaches one machine's instance. The broker
credential the mesh writes carries `claims`: each seat the module claims, its scope, and the verbs
the seat promises, so the runtime serves them on the seat's subjects; the holder's grant, composed
from the holding, is what admits the subscription.

internal/broker/invokes_test.go

@@ -91,3 +91,16 @@ func TestADeclaredInvokeReachesTheComposedUser(t *testing.T) {
 	}
 	has(t, perms.Publish, "mesh.mod.*.tool.>")
 }
+
+// A module's tool is addressed two ways (novox/hq ADR 0159): to whichever instance answers, and to
+// the instance on one machine. A grant for the tool covers both and nothing wider.
+func TestInvokingAToolMayAddressTheMachineToo(t *testing.T) {
+	got, err := invokedSubjects([]string{"postgres.postgres_query"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := []string{"mesh.mod.postgres.tool.postgres_query", "mesh.mod.postgres.tool.postgres_query.*"}
+	if len(got) != 2 || got[0] != want[0] || got[1] != want[1] {
+		t.Fatalf("the grant is %v, want %v", got, want)
+	}
+}