client-reliability-3: cancel queued torrent probes after last card owner disposes

docs/TODO.md

@@ -14,3 +14,5 @@
 - 2026-10-19: client-reliability-1 and client-reliability-2 ready for normal landing at181eae95: profile27/27 and race1/1 natural exit; all425 unit files passed with60s/file bound; lint11/11. Four deliberately broken variants fail and are reverted. Dispatch routing unblocked the second item; no product Nostr/shared-runner changes. Remaining: durable normal queue landing, unstable verification, then backlog close. Browser/build and real IO unverified (test-only scope). See test_logs/TEST_LOG_2026-10-19_20-35-00_client-reliability-both.md.
 
 - 2026-10-19: client-reliability-1 and client-reliability-2 finished: durable normal-gate landing de6918ce (submission683cedf0), gate exit0 and unstable ancestry verified. Profile27/27, race1/1 natural exit, lint11/11, full425/425 file exits0; all four mutants rejected. Backlog closed after landing. No unfinished product work for these items; browser/build/real IO unverified (test-only scope). Closure metadata queued separately; see test_logs/TEST_LOG_2026-10-19_20-34-50_client-reliability-landed.md.
+
+- 2026-10-19: client-reliability-3 implemented at current worktree: actual five-card obsolete starts1→0 after last-owner disposal; shared queued/live owners and active probe cache preserved; inflight identity and stale registration guards. Focused25/25 across4 files,11 mutants rejected, lint11/11, build/artifact verification pass, native Chromium/Firefox built-dist lifecycle smoke pass with0 external requests/page errors. Remaining: committed merged-tree full426-file gate, normal landq, durable ancestry/close and dispatch events. Active abort, URL probes, actual media fallback/peers and CPU/RSS unverified/out of scope; entire Stage3 performance plan is not complete.

docs/agents/backlog/client-reliability-3.json

@@ -1,7 +1,7 @@
 {
  "id": "client-reliability-3",
  "area": "client-reliability",
- "status": "open",
+ "status": "in-progress",
  "title": "Cancel queued torrent health probes when their last feed owner is disposed",
  "blockedOn": null,
  "addedOn": "2026-10-19",