mesh-controller.try fault A: decide drop-only dead letters by a module's own retention: work-queue, not by the bus's work-queue retention alone (issue 1178)

sourceAge keyed AgainTo's clause-6 refusal on the stream's bus retention
policy, which SEAT_* and other mesh-internal work queues share without
being one of ADR 0436 §6's module streams — so every seat's ask, once
given up on, was refused delivery again. Added a dedicated metadata key
(WorkQueueMetadata), set only by ModuleStream.Stream() when the
catalogue declared retention: work-queue, and read sourceAge from that
instead of the stream's retention policy. New test proves a seat's own
work queue carries neither that metadata nor the restricted one.

internal/link/deadletters.go

@@ -100,8 +100,16 @@ const withheldWords = "its body and its own headers are not shown: it came from
 	"the modules its grant names may read (novox/hq ADR 0376)"
 
 // sourceAge is whether a stream is restricted (novox/hq ADR 0363 §4; a work-queue stream is restricted too,
-// novox/hq ADR 0436 §6, aged and hidden the same way), whether it is a work queue, and its maximum age: read
-// from the stream itself, where the controller says all three. A stream that no longer exists is neither.
+// novox/hq ADR 0436 §6, aged and hidden the same way), whether it is a module stream declared retention:
+// work-queue, and its maximum age: read from the stream itself, where the controller says all three. A
+// stream that no longer exists is neither.
+//
+// **The module declaration, never the bus's work-queue retention alone** (novox/hq ADR 0436 §6, found by
+// mesh-controller.try on d8249dad): SEAT_* and other mesh-internal streams are JetStream work queues too —
+// exactly one worker takes each ask (ADR 0264 §4) — and their dead letters are still delivered again. Only
+// a module stream the catalogue declared retention: work-queue says so in its own metadata
+// (broker.WorkQueueMetadata, set by ModuleStream.Stream() alone); checking the bus's retention policy
+// caught every seat's queue too and refused every ask ever given up on delivered again.
 func sourceAge(js nats.JetStreamContext, stream string) (restricted, workQueue bool, maxAge time.Duration, err error) {
 	info, err := js.StreamInfo(stream)
 	if errors.Is(err, nats.ErrStreamNotFound) {
@@ -110,8 +118,8 @@ func sourceAge(js nats.JetStreamContext, stream string) (restricted, workQueue b
 	if err != nil {
 		return false, false, 0, fmt.Errorf("whether %s is restricted cannot be read: %w", stream, err)
 	}
-	workQueue = info.Config.Retention == nats.WorkQueuePolicy
-	return info.Config.Metadata[broker.RestrictedMetadata] == "true", workQueue, info.Config.MaxAge, nil
+	return info.Config.Metadata[broker.RestrictedMetadata] == "true",
+		info.Config.Metadata[broker.WorkQueueMetadata] == "true", info.Config.MaxAge, nil
 }
 
 // ttlOf is a time left as a message's time to live, in whole seconds and never more than what is left.

internal/link/deadletters_work_queue_test.go

@@ -31,6 +31,25 @@ func TestAWorkQueueStreamIsRestrictedOnTheBus(t *testing.T) {
 	}
 }
 
+// mesh-controller.try fault A, d8249dad: a seat's own work queue (SEAT_*, novox/hq ADR 0190, ADR 0264 §4) is
+// a JetStream work queue at the bus level too — exactly one worker takes each ask — but it is never a module
+// stream the catalogue declared retention: work-queue (ADR 0436 §6), so it carries none of that clause's
+// metadata and its dead letters are still delivered again (ADR 0264 §4), unlike mail-sends'.
+func TestASeatsWorkQueueIsNotADR0436WorkQueue(t *testing.T) {
+	seatQueue := broker.Stream{Name: "SEAT_NODE_BUILD_AGENT", Retention: broker.RetentionWorkQueue, DiscardNew: true}
+	cfg := broker.StreamConfigFor(seatQueue)
+	if _, has := cfg.Metadata[broker.WorkQueueMetadata]; has {
+		t.Fatalf("a seat's own work queue carries ADR 0436 §6's metadata: %+v", cfg.Metadata)
+	}
+	if _, has := cfg.Metadata[broker.RestrictedMetadata]; has {
+		t.Fatalf("a seat's own work queue is restricted: %+v", cfg.Metadata)
+	}
+	// sourceAge (deadletters.go) reads exactly these two keys off a real stream's config; neither set means
+	// KeepDeadLetter marks a seat's dead letter WorkQueue: false, so AgainTo never reaches clause 6's
+	// drop-only case for it (proven directly in TestAWorkQueueDeadLetterIsNeverDeliveredAgain) and a seat's
+	// ask is still delivered again (ADR 0264 §4), as it was before this release.
+}
+
 // 1178/AC3: a dead letter's headers say it came from a work-queue stream, and reading it back carries that
 // (and the restricted flag its aging and hiding already key off, deadLetterOf being the one place both are
 // read: see DeadLetter.Restricted's doc).