broker: DeadLetterReads grants only what a pulled ordered consumer needs, as mesh-sdk buscompose (issue 734, review round 1)

NATS-native research piece: none moved; the copy stays in step with mesh-sdk until mesh-grants composes the list.

internal/broker/seattraffic.go

@@ -157,7 +157,7 @@ func SeatTrafficOf(module string, holds, uses, watches []Seat) SeatTraffic {
 
 // DeadLetterReads is what a user of a seat pulled by kind is granted to hear which of the asks it put the seat's workers
 // gave up on (novox/hq issue 734): an ordered consumer on DEAD_LETTERS filtered to the copies the controller keeps of that
-// seat's stream (DeadLetterSubject(stream, *)), pulled or pushed, its deletion and its flow control. A copy carries the ask's own message id
+// seat's stream (DeadLetterSubject(stream, *)), pulled, and its deletion. A copy carries the ask's own message id
 // (Mesh-Dead-Msg-Id), so the asker ends the step it waits for instead of waiting for ever; it reads the seat's dead
 // letters and no other stream's, and changes none.
 func DeadLetterReads(stream string) []string {
@@ -165,8 +165,7 @@ func DeadLetterReads(stream string) []string {
 		"$JS.API.STREAM.INFO." + DeadLettersStream,
 		"$JS.API.CONSUMER.CREATE." + DeadLettersStream + ".*." + DeadLetterSubject(stream, ">"),
 		"$JS.API.CONSUMER.MSG.NEXT." + DeadLettersStream + ".*",
-		"$JS.API.CONSUMER.DELETE." + DeadLettersStream + ".>",
-		"$JS.FC." + DeadLettersStream + ".>",
+		"$JS.API.CONSUMER.DELETE." + DeadLettersStream + ".*",
 	}
 }
 

internal/broker/seattraffic_test.go

@@ -410,6 +410,7 @@ func TestTheBuilderMayAskABuildSeatAndASessionMayNot(t *testing.T) {
 		"$JS.API.CONSUMER.MSG.NEXT.DEAD_LETTERS.x1":                                     true,
 		"$JS.API.CONSUMER.CREATE.DEAD_LETTERS.x1.mesh.events.dead.EVENTS.>":             false,
 		"$JS.API.STREAM.PURGE.DEAD_LETTERS":                                             false,
+		"$JS.FC.DEAD_LETTERS.x1":                                                        false,
 	} {
 		if got := allowed(builder.Publish, subject); got != want {
 			t.Errorf("the builder may publish %s: %v, want %v", subject, got, want)