A claim may name the verbs it serves for its seat (hq ADR 0160)

The store's databases is not postgres's postgres_list_databases, and a holder may serve both. A
claim's serves names the seat's verbs the module implements for the role; absent, the module's own
tools must list every verb the seat promises, which is how a module named like its seat says they
are one and the same. Registration refuses a claim naming a verb the seat never promised, and the
credential's claims carry the claim's own verbs to the runtime.

internal/catalogue/seats.go

@@ -295,11 +295,19 @@ func CanHold(m Manifest, seat Seat) error {
 	// **Serving the seat's tools is a condition of holding it** (novox/hq ADR 0132). A holder that
 	// does not answer what the role promises is every caller's timeout, found at registration and
 	// at handover instead, naming the verbs rather than the fact that something is missing.
-	if missing := unservedVerbs(m.Tools, seat.Serves); len(missing) > 0 {
+	if missing := unservedVerbs(claimed.ServesFor(m), seat.Serves); len(missing) > 0 {
 		return fmt.Errorf("%s claims %s but does not serve %s, which that seat's protocol promises "+
-			"(novox/hq ADR 0132) — a holder lists every verb its seat declares under tools",
+			"(novox/hq ADR 0132) — a holder names every verb its seat declares, under the claim's "+
+			"serves or among its own tools",
 			m.Module, seat.Name, strings.Join(missing, ", "))
 	}
+	// And nothing the seat does not promise: a verb named here that the protocol lacks is served
+	// to nobody, which is a typo the holder would otherwise discover as a caller's timeout.
+	if extra := unpromised(claimed.Serves, seat.Serves); len(extra) > 0 {
+		return fmt.Errorf("%s claims %s and says it serves %s, which that seat's protocol does not "+
+			"promise — a claim's serves names the seat's verbs and nothing else",
+			m.Module, seat.Name, strings.Join(extra, ", "))
+	}
 	return nil
 }