Issue 334 and ADR 0264: an ask a seat gave up on can only be dropped for now

The review refused a grant over every seat's queue, and a copy published
again left the original stuck in it.

02-DECISIONS/0264-a-message-a-consumer-gives-up-on-is-kept-until-a-person-delivers-it-again-or-drops-it.md

@@ -84,11 +84,13 @@ Three things the mesh had decide the shape:
 4. **The controller's verb `dead-letters`** lists what DEAD_LETTERS holds, newest first, or for one
    consumer; shows one whole by its id; **delivers one again** to the consumer that gave it up; or **drops
    one**. Delivering again and dropping each require `why`, are recorded in the hand-act log first, and are
-   a person's decision, not a repair (S15 does not count them). An event is delivered again on the
-   consumer's again subject; an ask to a seat back on its own subject, since a seat's queue has one worker.
-   A message from any other stream, or a record without its message, can only be dropped, and the verb says
-   why. Delivering again carries the message's id, so asking twice delivers once. It is served by the
-   serving controller on its own connection, not by a fresh process.
+   a person's decision, not a repair (S15 does not count them). Only an event is delivered again, on the
+   consumer's again subject, and only when that consumer is on the bus and filters its again subject: a
+   dead letter is never let go as delivered while nothing would receive it. An ask a seat's worker gave up
+   on, a message from any other stream, and a record without its message can only be dropped, and the verb
+   says why (asks: [issue 334](../04-ISSUES/334-an-ask-a-seats-worker-gave-up-on-can-only-be-dropped/00-report.md)).
+   Delivering again carries the message's id, so asking twice delivers once. It is served by the serving
+   controller on its own connection, not by a fresh process.
 5. **The `max-deliveries` condition is open while DEAD_LETTERS holds a message for that consumer**, one
    condition per consumer, and clears when its messages are delivered again or dropped, never because the
    server stopped saying it. Its words say who gave up on how many messages, that what they asked for was
@@ -103,9 +105,10 @@ Three things the mesh had decide the shape:
 
 - Design 25 §1, §3 and §10 hold. The stream §3 names `mesh.events.dead` is DEAD_LETTERS; its subjects carry
   the stream and consumer.
-- The controller may publish on `mesh.events.dead.>`, `mesh.again.>` and every seat's `accept` subjects
-  (to give an ask back to its seat), and acknowledge on DEAD_LETTER_NOTICES. It already reached the stream
-  API.
+- The controller may publish on `mesh.events.dead.>` and `mesh.again.>`, and acknowledge on
+  DEAD_LETTER_NOTICES. It already reached the stream API. It gets no grant over the seats' queues.
+- Taking the notices never stops the controller serving: when they cannot be taken, that is said as a
+  condition (`not-kept`) and tried again every minute.
 - Every module's consumer changes once, when its filters gain its again subject. Its position is kept.
 - A message given up on is now visible and costs space until somebody acts. A consumer that gives up on
   many fills DEAD_LETTERS; full, further copies are refused and said, which is the loud failure the mesh
@@ -122,7 +125,9 @@ Three things the mesh had decide the shape:
   its consumer, stream, subject, deliveries and the time it was given up. It fails on the commit before the
   fix and passes on it.
 - mesh-controller `internal/link/deadletters_test.go`: delivered again, an event reaches the consumer that
-  gave it up and not another module that handled it; it is no longer kept, and a second delivery finds
+  gave it up and not another module that handled it; one is refused, and kept, when its consumer is gone or
+  does not filter its again subject, and when it is not an event; the list's total is the held count however
+  few it lists; notices that cannot be taken are said while the controller serves on; it is no longer kept, and a second delivery finds
   nothing; a dropped one is gone; a notice whose message is gone is kept as a record that cannot be
   delivered again; a notice taken twice is kept once; the controller acts on its own event delivered again.
 - mesh-controller `cmd/mesh-controller/deadletters_test.go`: the verb lists, refuses an act without why or