The node seat node-engine served on the engine's link: its verbs with their proven caller, its acts kept in its own state, a hand-over or access act asked of the operator as node-engine-<node> and performed only on the warrant (issue 774, ADR 0563 §1-§3)

internal/link/hearing_nats.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/micro"
 )
 
 // The host's link on the bus: one connection, and what is asked of this node over it. The node hears no declaration
@@ -48,7 +49,10 @@ type natsLink struct {
 	acting *nats.Subscription
 	// moving hears the controller asking to move a value sealed to this machine into the vault (issue 676).
 	moving *nats.Subscription
-	node   string
+	// engine serves the node seat node-engine, and warrants hears the operator's answers to its asks (ADR 0563).
+	engine   micro.Service
+	warrants *nats.Subscription
+	node     string
 	// signer is the mesh's key, which a hand-over ask is verified with as a declaration is (issue 356).
 	signer ed25519.PublicKey
 	lost   chan error
@@ -258,6 +262,12 @@ func (l *natsLink) Close() {
 	if l.judging != nil {
 		_ = l.judging.Unsubscribe()
 	}
+	if l.engine != nil {
+		_ = l.engine.Stop()
+	}
+	if l.warrants != nil {
+		_ = l.warrants.Unsubscribe()
+	}
 	if l.conn != nil {
 		l.conn.Close()
 	}
@@ -301,10 +311,12 @@ func (l *natsLink) Ask(ctx context.Context, subject string, body []byte) ([]byte
 // What the queue asks of a live link beside Bus, each by a type assertion that fails quietly: said here
 // so a link that drops one does not build.
 var (
-	_ Bus       = (*natsLink)(nil)
-	_ HealthBus = (*natsLink)(nil)
-	_ HaveBus   = (*natsLink)(nil)
-	_ ToolBus   = (*natsLink)(nil)
-	_ Asker     = (*natsLink)(nil)
-	_ Asked     = (*natsLink)(nil)
+	_ Bus          = (*natsLink)(nil)
+	_ HealthBus    = (*natsLink)(nil)
+	_ HaveBus      = (*natsLink)(nil)
+	_ ToolBus      = (*natsLink)(nil)
+	_ Asker        = (*natsLink)(nil)
+	_ Asked        = (*natsLink)(nil)
+	_ EngineSeats  = (*natsLink)(nil)
+	_ OperatorAsks = (*natsLink)(nil)
 )