Keep a question's slot until it expires while the router has not recorded it (issue 589, review 107)

Freeing the slot two minutes after asking could let a backlogged router still show
the question after the session read it as ended, and let a third question in. The
seat's queue offers work again after an error and the router drops a cancel of an
ask it has not recorded, so a cancel cannot take it back; once expired, the router
refuses it if taken late. The slot test now uses a stale revision, so a plain
write in place of the compare-and-set fails it.

modules/claude-code/README.md

@@ -177,8 +177,10 @@ after expiry is never read as a choice. One call waits at most 60 s; the tool as
 most once a minute, and nothing enforces it. At most two questions wait at once, mesh-wide: each holds one of two
 slot keys in `questions`, taken by create or compare-and-set, so two nodes asking at once cannot both take the last,
 and a slot that cannot be read refuses the question. Questions alone never fill the router's three open asks, so one
-is left for a proposed instruction section while two are open. A question the router holds no record of two minutes
-after it was asked (its refusal not heard here) frees its slot and reads as ended. A refused question keeps none of
+is left for a proposed instruction section while two are open. A question the router holds no record of, its refusal
+not heard here, keeps its slot and reads as waiting until it expires: the router may still take it from its queue,
+and no cancel can overtake it there (the queue offers work again after an error, and a cancel of an ask not yet
+recorded is dropped); once expired, the router refuses it if taken late. A refused question keeps none of
 its words. An answer is the operator's word to the session and authorises nothing; a question never defaults.
 
 The home scope is registered through the tools **only where the home belongs to an agent account of its own**