spec(ha-commit-durability): 6.1 answered — durability loss + liveness are REAL (reproduce off overlay), not an fdatasync artifact; Phase 6 now at 6.2 root-cause

.kiro/specs/ha-commit-durability/research.md

@@ -204,3 +204,17 @@ After the `xce-test-e2e-primitives` soak was HARDENED (commit d82cc78: it no lon
 2. **Separate LIVENESS concern:** every run shows 2–3 rounds where, after killing the current primary (consistently `ctrl-1`), NO new primary served within 60s (the cluster always eventually recovered). A >60s failover for a single-node kill in a 3-node cluster is poor availability and may share a root cause with the durability race (a behind/just-rejoined node interacting with the promotion fence / freshness floor). Worth a dedicated liveness check in 6.2.
 
 **Phase 6 scope note:** 6.1's reproduction MUST include BOTH the cold-restart-all step AND the rolling-failover rounds (the hardened soak runs both and reports trustworthy per-round verdicts), and should capture the >60s-election cases for the liveness angle.
+
+### UPDATE 2026-06-19c — 6.1 ANSWERED: the loss is REAL, not (only) an overlay artifact
+
+The cold-restart-all / rolling durability loss was initially suspected to be an overlay-`/tmp` `fdatasync`-EIO artifact of the dev sandbox. That is now ruled out as the primary cause:
+- **User runs the soak OUTSIDE the container** (real host, real fsync-able fs, NO overlay `fdatasync` EIO) and still observes the DATA LOSS + the liveness failures. So they are genuine, not sandbox `fdatasync` noise.
+- In-sandbox confirmation on a **real ext2/3 deploy dir** (`fdatasync` succeeds, ZERO EIO): a 3-round run PASSED clean, but an 8-round run reproduced BOTH a liveness cascade (after killing `ctrl-1` in round 1 the cluster never returned to 3-healthy) AND a cold-restart `expect-jobs` shortfall with a PERSISTENTLY-absent committed job — with **zero `fdatasync` EIO**. (Caveat: the 8-round run's cold-restart followed a degraded run, so the cleanest real-fs evidence is the user's outside-container host.)
+
+**Verdict for 6.1:** the durability loss and the liveness stall reproduce off overlay → REAL controller findings, not an `fdatasync`-EIO artifact. The overlay EIO remains a SEPARATE, sandbox-only confound (it makes the dev-box `controller_unit_test` flaky — see bug-760 — and inflates loss on overlay deploys), but it is not the root cause of the soak loss.
+
+**Phase 6 is now at 6.2 (root-cause).** Two real, non-deterministic findings to root-cause:
+- **Durability:** an acked (`jobsubmit ok`) job is PERSISTENTLY absent from a SERVING cluster after failover / cold restart — i.e. bug-661 is NOT fully closed (Phase 5 only exercised rolling single-node kills with the racy soak). Buckets: acked-without-durable-majority (commit-gate timing) / recovery truncates committed entries / behind-then-killed node re-leads with a truncated log.
+- **Liveness:** after killing the current primary (consistently `ctrl-1` in these runs), the cluster sometimes takes >60s — or fails entirely — to elect a serving primary, and a restarted node sometimes never returns to a healthy 3-node serving set. Possibly coupled to the promotion-fence / freshness-floor interaction with a just-rejoined node.
+
+The hardened `xce-test-e2e-primitives` soak (trustworthy: liveness vs durability separated, confirm-settle, quiet wait-primary) is the reproduction surface for both.

.wolf/buglog.json

@@ -13003,8 +13003,8 @@
       "id": "bug-795",
       "timestamp": "2026-06-19",
       "error_message": "Cold-restart-all (kill ALL 3 controllers + restart) non-deterministically loses a committed job: a job that returned 'jobsubmit ok' and survived every rolling single-node failover round vanishes after a full-cluster restart (expect-jobs expected N, actual N-2; expect-job <id> not found). Recovery logs show WAL truncate.",
-      "file": "src/controller/persist.c (recovery/truncation) + commit/replication path \u2014 UPSTREAM (ha-commit-durability), NOT xce-test-e2e-primitives",
-      "root_cause": "Commit-durability race under TOTAL-cluster-outage recovery. Acked (committed) entry not durable on a fault-tolerant majority before all nodes die, OR recovery truncates committed entries on cold restart. Non-deterministic (passed 1 run, failed next). Surfaced on overlayfs sandbox (NOT a real fsync-able fs) \u2014 must be reconfirmed on real hardware. UPDATE: with the hardened (trustworthy) soak, the loss ALSO reproduces in ROLLING single-node failover with the cluster confirmed serving (~1/3 runs) \u2014 broader than cold-restart-all; bug-661 not fully closed for rolling failover. Separate finding: >60s post-kill election (liveness) every run, always recovers.",
+      "file": "src/controller/{persist.c recovery/truncate, commit.c commit-gate, ha.c promotion-fence/election} \u2014 UPSTREAM ha-commit-durability Phase 6.2",
+      "root_cause": "Commit-durability race under TOTAL-cluster-outage recovery. Acked (committed) entry not durable on a fault-tolerant majority before all nodes die, OR recovery truncates committed entries on cold restart. Non-deterministic (passed 1 run, failed next). Surfaced on overlayfs sandbox (NOT a real fsync-able fs) \u2014 must be reconfirmed on real hardware. UPDATE: with the hardened (trustworthy) soak, the loss ALSO reproduces in ROLLING single-node failover with the cluster confirmed serving (~1/3 runs) \u2014 broader than cold-restart-all; bug-661 not fully closed for rolling failover. Separate finding: >60s post-kill election (liveness) every run, always recovers. CORRECTION: NOT an overlay-fdatasync artifact \u2014 reproduces OUTSIDE the container (user's real host) AND on an in-sandbox real ext2/3 fs with ZERO fdatasync EIO. Real controller durability bug + a coupled liveness stall (>60s / stuck election after killing ctrl-1). Phase 6.1 answered (REAL); now at 6.2 root-cause.",
       "fix": "NOT FIXED HERE \u2014 out of boundary for xce-test-e2e-primitives (this spec changes no controller/replication code). Routed to spec ha-commit-durability owner. The converted durability soak (src/tools/test-commit-durability.sh, new run_cold_restart_recovery phase) correctly detects it via the exit-code verdict.",
       "tags": [
         "ha-commit-durability",
@@ -13024,7 +13024,7 @@
         "bug-778",
         "bug-786"
       ],
-      "occurrences": 2,
+      "occurrences": 3,
       "last_seen": "2026-06-19"
     },
     {