fix9b2-1b: FollowAssignmentsIn takes the bucket; FollowAssignments keeps the fixed one for the checker, which another change owns

Builds: design 47 G A-119

modules/mesh-delivery-builder/buildrun/standing.go

@@ -125,11 +125,18 @@ func (g *ToolchainGate) placedTold() {
 	}
 }
 
-// FollowAssignments reads the seat mesh-module-assigner's assignments, in bucket (the seat's holder found at run time, `<holder>_assignments`; design 47 G A-119), with its history into gate, says it settled, and follows it; changed
+// FollowAssignments reads the seat mesh-module-assigner's assignments with its history into gate, says it settled, and follows it; changed
 // is told whenever what the gate passes on changed. Where the state cannot be read or watched (not there, or this part
 // may not read it) it says so and the gate passes every report on: not fatal, since an indexer, builder or checker that
 // stops for it stops every delivery (issue 1945). An error of the watch after that ends on the channel.
-func FollowAssignments(ctx context.Context, js process.BucketOpener, bucket string, gate assignmentsFollowed, changed func(context.Context), logf func(string, ...any)) (<-chan error, error) {
+func FollowAssignments(ctx context.Context, js process.BucketOpener, gate assignmentsFollowed, changed func(context.Context), logf func(string, ...any)) (<-chan error, error) {
+	return FollowAssignmentsIn(ctx, js, AssignmentsBucket, gate, changed, logf)
+}
+
+// FollowAssignmentsIn is FollowAssignments for the state in bucket, the holder's `<holder>_assignments` where the holder is found at
+// run time (design 47 G A-119): the builder follows it so; FollowAssignments, with the fixed bucket, is the checker's until its own
+// change finds the holder.
+func FollowAssignmentsIn(ctx context.Context, js process.BucketOpener, bucket string, gate assignmentsFollowed, changed func(context.Context), logf func(string, ...any)) (<-chan error, error) {
 	errs := make(chan error, 1)
 	kv, err := js.KeyValue(ctx, bucket)
 	if err != nil {

modules/mesh-delivery-builder/buildrun/standing_test.go

@@ -86,7 +86,7 @@ func TestPlacedNodes(t *testing.T) {
 		refused := errors.New("nats: permissions violation for publish to $JS.API.CONSUMER.CREATE.KV_mesh-delivery-assigner_assignments")
 		gate := NewPlacedNodes(logger.Printf)
 		for _, bus := range []refusingBus{{err: refused}, {refuseOpen: true, err: refused}} {
-			if _, err := FollowAssignments(context.Background(), bus, AssignmentsBucket, gate, func(context.Context) {}, logger.Printf); err != nil {
+			if _, err := FollowAssignments(context.Background(), bus, gate, func(context.Context) {}, logger.Printf); err != nil {
 				t.Errorf("a refused assignments stopped the start: %v", err)
 			}
 		}

modules/mesh-delivery-builder/buildrun/toolchaingate_test.go

@@ -249,7 +249,7 @@ func TestToolchainGate(t *testing.T) {
 		refused := errors.New("nats: permissions violation for publish to $JS.API.CONSUMER.CREATE.KV_mesh-delivery-assigner_assignments")
 		gate, _, _ := start(t, false)
 		for _, bus := range []refusingBus{{err: refused}, {refuseOpen: true, err: refused}} {
-			if _, err := FollowAssignments(context.Background(), bus, AssignmentsBucket, gate, func(context.Context) {}, logger.Printf); err != nil {
+			if _, err := FollowAssignments(context.Background(), bus, gate, func(context.Context) {}, logger.Printf); err != nil {
 				t.Errorf("a refused assignments stopped the start: %v", err)
 			}
 		}

modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go

@@ -362,7 +362,7 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 			return
 		case <-assignments.Follower().Ready():
 		}
-		pe, err := buildrun.FollowAssignments(ctx, reader, names.Bucket, gate, b.NodesChanged, logger.Printf)
+		pe, err := buildrun.FollowAssignmentsIn(ctx, reader, names.Bucket, gate, b.NodesChanged, logger.Printf)
 		if err != nil {
 			assignmentsErrs <- err
 			return