Ask the operator for a condition's answers and act on the warrant, so release, stop, start and restart can be answered from any channel that proves who answered (hq ADR 0259)

internal/link/serve.go

@@ -70,7 +70,7 @@ type Checker interface {
 }
 
 // PullUpdatedSubject is where the forge's pull requests land: the controller's own follow of them.
-var PullUpdatedSubject = broker.ControllerFollows[len(broker.ControllerFollows)-1]
+var PullUpdatedSubject = "mesh.mod.gitea.event.pull.updated"
 
 // Server acts on what nodes and modules say.
 //
@@ -96,6 +96,8 @@ type Server struct {
 	checker Checker
 	// healths keeps what machines say of their long-running resources (novox/hq ADR 0240).
 	healths Healths
+	// decider acts on the operator's warrants for what the controller asked (novox/hq ADR 0259).
+	decider Decider
 
 	log *log.Logger
 	// giveUp is how long one message is held for the store; zero means GiveUpAfter.
@@ -138,6 +140,21 @@ func (s *Server) Checks(c Checker) error {
 	return nil
 }
 
+// Decider is what the controller does with the router's word on an ask it made (novox/hq ADR 0259): act
+// on a warrant once, or record how the ask ended without one.
+type Decider interface {
+	Decided(ctx context.Context, body []byte) error
+}
+
+// Decides says what to do about the router's word on the controller's asks, and asks for it delivered.
+func (s *Server) Decides(d Decider) error {
+	if err := s.inbound.Also(KindDecided); err != nil {
+		return err
+	}
+	s.decider = d
+	return nil
+}
+
 // Answers says what to do about a catalogue's catch-up request, and asks for them to be delivered.
 func (s *Server) Answers(r Replayer) error {
 	if err := s.inbound.Also(KindCatchUp); err != nil {
@@ -210,6 +227,8 @@ func (s *Server) act(ctx context.Context, m Control) {
 		s.provisioner(ctx, m)
 	case KindPullUpdated:
 		s.pullUpdated(ctx, m)
+	case KindDecided:
+		s.decided(ctx, m)
 	default:
 		// Dropped: a message nothing understands will not be understood on the next attempt
 		// either, and asking for it again would spin.
@@ -656,6 +675,24 @@ func (s *Server) pullUpdated(ctx context.Context, m Control) {
 	_ = m.Took()
 }
 
+// decided hands the router's word on an ask to the decider; a failure to keep what it did is held for the
+// store, like any word that must not be lost.
+func (s *Server) decided(ctx context.Context, m Control) {
+	if s.decider == nil {
+		_ = m.Took()
+		return
+	}
+	err := s.decider.Decided(ctx, m.Body())
+	switch s.decide(ctx, m, "the operator's word on an ask", "", "", err) {
+	case Hold:
+		return
+	}
+	if err != nil {
+		s.log.Printf("the operator's word on an ask could not be kept: %v", err)
+	}
+	_ = m.Took()
+}
+
 // saysWhatItDid states what a machine now runs, or what it would not take, as a fact on the bus
 // (novox/hq ADR 0134).
 //