Merge master (exp-v0.52.354) into stage/7761-watcher-fence

# Conflicts:
#	CHANGELOG.md

CHANGELOG.md

@@ -32,6 +32,12 @@
   leaves.** Final unsubscribe and queue eviction now invalidate the cache and fence projections that
   were already in flight, without holding the lock across database reads or SSE writes, so a client
   that re-subscribes gets a fresh snapshot instead of a stale one. (#7761 by @ruizanthony)
+- **A burst of "session busy" refusals no longer drops a background-task completion.** When
+  `start_session_turn()` refused a completion wake-up with a transient 409 (Agent runtime stale,
+  process wake-ups paused, or the session busy with another turn), the bridge released the durable
+  claim as a plain failure, so a few refusals in a row could terminally drop a completion whose
+  session was alive and waiting. Transient refusals now return the claim as retryable, while hard
+  failures still use up the attempt budget. (#7758 by @ruizanthony)
 - **A first visit now uses the browser's language.** The server stores "no preference" as `null`
   instead of defaulting to `"en"`, so a first-time visitor gets `navigator.language` while an
   explicitly saved language (including English) still wins, and legacy `settings.json` files that