feat(ha-convergence-recovery): quorum transition logging — CAS edge-detect + 4 call sites (task 5.2)

.kiro/specs/ha-convergence-recovery/tasks.md

@@ -59,13 +59,13 @@
   - Observable completion: all task 4.1 tests PASS; heartbeat decision loop diff-clean (fallback + snapshot initiator preserved)
   - _Requirements: 5.1, 5.2, 5.3, 7.1_
 
-- [ ] 5. Quorum transition observability
+- [x] 5. Quorum transition observability
 - [x] 5.1 Write RED tests for once-per-transition quorum logging
   - Tests in `test_convergence_verification.c` (log-capture or counter-hook pattern): dropping standbys below majority logs the loss WARN exactly once with connected/required counts; repeated dispatch-gate rejections while quorum stays lost add no further transition logs; restoring a standby logs the restore WARN once; a second loss/restore cycle logs again (edge detector, not a latch)
   - Observable completion: new cases FAIL (red) — no transition logging exists (ha.c:1507-1525 anchor)
   - _Requirements: 8.1, 8.2, 8.3_
 
-- [ ] 5.2 Implement quorum transition logging to green
+- [x] 5.2 Implement quorum transition logging to green
   - ha.h: `_Atomic int quorum_lost` on `ha_state_t`; ha.c: `ha_log_quorum_transition(ha)` — CAS edge detection around `ha_has_write_quorum`, WARN with connected/required counts on each edge only
   - Call sites: promotion standby registration (ha.c:531 anchor — NOTE: this anchor is inside `raft_cb_become_leader` (ha.c:445-617), promotion code owned and rewritten wholesale by ha-single-leader-role; re-anchor after that spec lands, or coordinate with it if this task is implemented first), RDHUP removal (ha.c:3160-3166 anchor), `on_standby_connected` (ha.c:3764+ anchor), and the `ha_dispatch_gate` quorum-rejection branch as backstop
   - Observable completion: all task 5.1 tests PASS; no log line is emitted per rejected operation
@@ -105,3 +105,4 @@
 - **Disk space**: heavy nix builds can fill the root overlay with stale `/tmp/nix-shell.*` AND `/tmp/xce_*` test dirs (reviewers reclaimed ~16GB nix-shell + ~570GB stale xce test dirs). If a build/test fails on "No space left on device", clear stale `/tmp/nix-shell.*` and `/tmp/xce_*` and retry — not a code failure.
 - **Task 3.2 — delaymgr one-shot helper + once-guard test strength**: `ha_rejoin_reconcile` lives in `ha_convergence.c` (alongside `ha_self_restart`/demotion task, unit-linkable) and defers truncate→WARN→restart to a delaymgr one-shot, reusing the 2.2 pattern. The test helper `dc_run_pending_task` was fixed to DEQUEUE (`ordq_get`+free) mirroring the real delaymgr worker (delay.c:65-90) — the prior peek-without-dequeue caused a test-only heap-UAF (re-running an already-freed one-shot); production never re-runs a one-shot, so the body-frees-own-ctx pattern is safe (bug-343). **Follow-up (non-blocking, for task 6.1 or 7): add a once-guard test that calls `ha_rejoin_reconcile` TWICE before draining the delaymgr (tip unchanged) and asserts exactly one task scheduled** — the current second-call test runs truncation synchronously between calls, so call 2 exits at the 2.3 early-return and exercises only the structural guard, not the defensive CAS (CAS is present + correct, needed for a duplicate CtrlHelloReply arriving before the deferred truncation runs).
 - **Task 5.1 done (RED) + 5.2 notes**: counter-hook seam `ha_quorum_transition_log_hook(int lost,int connected,int required)` is the observable (no log-capture harness exists); `_Atomic int quorum_lost` added to ha_state_t; no-op stub `ha_log_quorum_transition` in ha_convergence.c. **5.2 must**: (a) report `connected = repl_active_standby_count(repl)` and `required = n_peers/2` to match the `ha_has_write_quorum` BODY (ha.c:~1488-1498) — its header comment says "ceil(n_peers/2)+1" but that's a pre-existing stale comment; do NOT change the quorum math, just mirror the body so the 5.1 tests pass; (b) re-grep the promotion standby-registration call site inside `raft_cb_become_leader` (rewritten by ha-single-leader-role) — RDHUP removal (~ha.c:3160), `on_standby_connected` (~ha.c:3764), and the gate-rejection backstop (~ha.c:1511) are verified present; (c) invoke the hook once per WARN emitted (CAS edge-detect on `quorum_lost`).
+- **Task 5.2 done (GREEN) — quorum-decision duplication note**: `ha_log_quorum_transition` (ha_convergence.c) re-derives `connected = repl_active_standby_count(repl)` / `required = n_peers/2` / single-node short-circuit as a FAITHFUL same-input mirror of the file-static `ha_has_write_quorum` (ha.c) — it cannot report a state inconsistent with the gate. Non-blocking maintainability risk: if `ha_has_write_quorum`'s decision ever changes, this mirror must change too. **Follow-up (optional cleanup): expose `ha_has_write_quorum` via a non-static accessor and call it from `ha_log_quorum_transition`** instead of duplicating. Call sites wired (post ha-single-leader-role rewrite): promotion ha.c:567, RDHUP removal ha.c:3180, on_standby_connected ha.c:3837, gate backstop ha.c:1521.