mesh-conditions: ListBound is asked again on the bus module's created or a node-engine's running, not on a timer

Builds: design 47 G §515, §663

Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h

modules/mesh-conditions/cmd/mesh-conditions/bound.go

@@ -7,7 +7,6 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"time"
 
 	broker "git.novox.be/novox/mesh-contracts/go/seats/meshbroker"
 )
@@ -48,10 +47,27 @@ func (k *Keeper) takeSource(module string) error {
 	return nil
 }
 
+// nudgeBound says, without waiting, that the bus module's entries may be read now (ListBound's retry).
+func (k *Keeper) nudgeBound() {
+	k.mu.Lock()
+	k.init()
+	c := k.boundRetry
+	k.mu.Unlock()
+	select {
+	case c <- struct{}{}:
+	default:
+	}
+}
+
 // ListBound reads the entries the bus module holds at the keeper's start: every module with a `finding-events` entry is a
-// source. A call that fails is asked again with a growing wait, the bus module being delivered after the keeper at times.
+// source. A call that fails is asked again on the next event that says the bus module may answer, its `created` or a
+// node-engine's `running` (the bus module being delivered after the keeper at times), never on a timer.
 func ListBound(k *Keeper, call func(key string, body any) (json.RawMessage, error)) {
-	for wait := 2 * time.Second; ; wait = min(wait*2, time.Minute) {
+	k.mu.Lock()
+	k.init()
+	retry := k.boundRetry
+	k.mu.Unlock()
+	for {
 		raw, err := call("seat:"+broker.Seat+"."+broker.VerbList, broker.ListInput{})
 		var answer broker.ListAnswer
 		if err == nil {
@@ -67,7 +83,7 @@ func ListBound(k *Keeper, call func(key string, body any) (json.RawMessage, erro
 			}
 			return
 		}
-		k.Logf("the entries of the bus module are not read yet (%v); asked again in %s", err, wait)
-		time.Sleep(wait)
+		k.Logf("the entries of the bus module are not read yet (%v); asked again when it says created or a node-engine says running", err)
+		<-retry
 	}
 }

modules/mesh-conditions/cmd/mesh-conditions/events.go

@@ -72,13 +72,17 @@ func (k *Keeper) FindingEvent(e stdio.Envelope) error {
 	if _, ok := emitterOf(e.Key, watchdogs.EventMachineBack); ok && strings.HasPrefix(e.Key, watchdogs.Seat+".") {
 		return k.MachinePresence(e.Body, false)
 	}
-	if _, _, _, ok := engineKey(e.Key); ok {
+	if event, _, _, ok := engineKey(e.Key); ok {
+		if event == engine.EventRunning {
+			k.nudgeBound()
+		}
 		return k.EngineEvent(e)
 	}
 	if strings.HasPrefix(e.Key, meshhealers.Seat+".attempt-changed.") {
 		return k.AttemptChanged(e.Key, e.Body)
 	}
 	if e.Key == broker.Seat+"."+broker.EventCreated {
+		k.nudgeBound()
 		return k.BrokerCreated(e.Body)
 	}
 	return nil

modules/mesh-conditions/cmd/mesh-conditions/keeper.go

@@ -164,6 +164,9 @@ type Keeper struct {
 	stopped    map[string]bool
 	// created are the modules whose `finding-events` entry the bus module made (bound.go).
 	created map[string]bool
+	// boundRetry is told, once, when the bus module says `created` or a node-engine says `running`: the events after which
+	// the entries of the bus module may be read (ListBound).
+	boundRetry chan struct{}
 	// followed are the finding streams the catalog half declared for each module, by module (catalog.go).
 	followed map[string]string
 }
@@ -179,6 +182,9 @@ func (k *Keeper) init() {
 		k.halves, k.placed, k.stopped = map[string]map[string]catseat.CatalogEntry{}, map[string]bool{}, map[string]bool{}
 		k.views, k.keyNode, k.whys = map[string]*sourceView{}, map[string]map[string]string{}, map[string]string{}
 	}
+	if k.boundRetry == nil {
+		k.boundRetry = make(chan struct{}, 1)
+	}
 	if k.Now == nil {
 		k.Now = time.Now
 	}

modules/mesh-conditions/cmd/mesh-conditions/keeper_test.go

@@ -723,3 +723,47 @@ func TestTheKeepersOwnFindingIsTheContractsFindingByItsWireForm(t *testing.T) {
 		t.Fatal("the condition stands after its finding was cleared")
 	}
 }
+
+// ListBound reads the bus module's entries once and, when the call fails, again on the event that says the bus module may
+// answer (its `created`, or a node-engine's `running`), never on a timer (design 47 G §515, §663).
+func TestListBoundIsAskedAgainOnTheEventsNotATimer(t *testing.T) {
+	for _, event := range []string{"mesh-broker.created", "node-engine.running.ace.mesh-conditions"} {
+		t.Run(event, func(t *testing.T) {
+			var asked []map[string]any
+			k := &Keeper{Publish: func(_ string, b any) error { asked = append(asked, b.(map[string]any)); return nil }}
+			calls := make(chan int)
+			ended := make(chan struct{})
+			go func() {
+				n := 0
+				ListBound(k, func(string, any) (json.RawMessage, error) {
+					n++
+					calls <- n
+					if n == 1 {
+						return nil, fmt.Errorf("the bus module is not delivered yet")
+					}
+					return mustJSON(t, map[string]any{"entries": []any{map[string]any{"module": "newpart", "template": FindingEventsTemplate}}}), nil
+				})
+				close(ended)
+			}()
+			<-calls
+			select {
+			case <-ended:
+				t.Fatal("ListBound ended with no answer")
+			default:
+			}
+			_ = k.FindingEvent(stdio.Envelope{Key: event, Body: []byte(`{}`)})
+			select {
+			case n := <-calls:
+				if n != 2 {
+					t.Fatalf("asked %d times", n)
+				}
+			case <-time.After(time.Second):
+				t.Fatal("not asked again on the event")
+			}
+			<-ended
+			if len(asked) != 1 || asked[0]["module"] != "newpart" {
+				t.Errorf("asked %v, want newpart once", asked)
+			}
+		})
+	}
+}