J2: the tool runner tells a subscribed bundle how its module's consumer stands, as mesh/heartbeat (stdio.OnHeartbeat), at each idle beat and once Missed (ADR 0615, ADR 0621, issue 1966)

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig

node-tools/internal/bus/consume_test.go

@@ -60,3 +60,72 @@ func TestASlowHandlerAndABurstAreEachHandedOverOnce(t *testing.T) {
 		}
 	}
 }
+
+// The runtime tells a bundle how its module's consumer stands between events (stdio.OnHeartbeat): a word at each
+// idle heartbeat while the bus answers, once Missed when the bus ended the loop, and a word again when it is bound again.
+func TestAConsumerSaysItIsBoundWhileIdleAndOnceWhenTheBusEndedIt(t *testing.T) {
+	mesh := mt.New(t)
+	restore := bus.IdleHeartbeat
+	bus.IdleHeartbeat = 200 * time.Millisecond
+	t.Cleanup(func() { bus.IdleHeartbeat = restore })
+	mesh.Consumer(t, "anchor", "quiet", []string{"mesh.mod.alpha.event.>"}, time.Second)
+	c, err := bus.Connect(bus.Credential{URL: mt.URL(t), Module: "node-tools", Node: "anchor"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.Logf = func(string, ...any) {}
+	t.Cleanup(c.Close)
+
+	var mu sync.Mutex
+	var beats []bus.Beat
+	stop, err := c.ConsumeAsBeating("quiet", func(bus.Envelope) error { return nil }, func(b bus.Beat) {
+		mu.Lock()
+		beats = append(beats, b)
+		mu.Unlock()
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(stop)
+	last := func() (bus.Beat, int) {
+		mu.Lock()
+		defer mu.Unlock()
+		if len(beats) == 0 {
+			return bus.Beat{}, 0
+		}
+		return beats[len(beats)-1], len(beats)
+	}
+	mt.Until(t, func() error {
+		if b, n := last(); n == 0 || b.Missed || b.At.IsZero() {
+			return fmt.Errorf("no word that the consumer is bound yet: %d beats", n)
+		}
+		return nil
+	})
+	mesh.RemoveConsumer(t, bus.EventsStream, "anchor", "quiet")
+	mt.Until(t, func() error {
+		if b, _ := last(); !b.Missed || b.Why == "" {
+			return fmt.Errorf("the consumer is gone from the bus and no Missed word came: %+v", b)
+		}
+		return nil
+	})
+	mu.Lock()
+	missed := 0
+	for _, b := range beats {
+		if b.Missed {
+			missed++
+		}
+	}
+	mu.Unlock()
+	time.Sleep(600 * time.Millisecond)
+	mu.Lock()
+	defer mu.Unlock()
+	after := 0
+	for _, b := range beats {
+		if b.Missed {
+			after++
+		}
+	}
+	if after != missed || missed != 1 {
+		t.Errorf("Missed is said once, not at every beat: %d then %d", missed, after)
+	}
+}