chore(wolf): checkpoint buglog.json (1025 bugs)

.wolf/buglog.json

@@ -18696,6 +18696,25 @@
       ],
       "occurrences": 2,
       "last_seen": "2026-08-25T00:20:00Z"
+    },
+    {
+      "id": "bug-1684",
+      "timestamp": "2026-08-25T00:50:00Z",
+      "error_message": "xce-audit-invariants controller audit (dimension: error handling) finding: raft_cb_persist() (src/controller/ha.c:2257) always returns 0 to the raft library's on_persist callback contract regardless of whether the term/voted_for durability write to disk actually succeeded -- a disk I/O failure (full disk, permission error, transient I/O error) could let a node grant a vote it has no durable record of, opening a split-vote path if that node then restarts and forgets it voted (Election Safety: 'a server grants at most one vote per term' via durably-persisted votedFor).",
+      "file": "src/controller/ha.c",
+      "root_cause": "src/lib/raft/raft.c:260-263's raft_on_vote_request Step 7 has an explicit durability-guarantee contract: 'if (s->cbs->on_persist(...) != 0) { /* Persist failed -- deny without updating voted_for */ return RAFT_DENY; }' -- the adapter's on_persist callback (raft_cb_persist) must return non-zero on a genuine persist failure. raft_cb_persist's own doc comment even claimed this contract ('Returns 0 on success, non-zero on error'), but its implementation called ha_persist_term(ha, workdir) and then unconditionally `return 0;` regardless of the outcome. ha_persist_term() itself (ha.c:5174) had a void return with every open()/write()/fsync() failure silently discarded (`if (fd < 0) return; /* best-effort; caller must not rely on this for correctness */`), so the failure was structurally invisible to the caller even before raft_cb_persist's own bug. Compounding: raft_cb_persist mutates ha->voted_for_term/ha->voted_for_name in-memory BEFORE calling ha_persist_term, so even fixing just the return-code propagation would leave the adapter's own in-memory state claiming a vote was cast that the raft library itself denied and never durably recorded -- a second-order inconsistency needing an explicit rollback.",
+      "fix": "FIXED (2026-08-25). ha_persist_term() (ha.c:5174, declared ha.h:1307) relocated from void to int -- returns 0 on success (including the deliberate NULL-workdir test-mode skip) or -errno on a genuine open/write/fsync/rename failure (fsync's own previously-unchecked return value is now checked too). raft_cb_persist() (ha.c:2257) now captures ha_persist_term's return, and on failure: (a) logs a loud ERROR with term/voted_for/rc, (b) rolls back ha->voted_for_term/ha->voted_for_name to their pre-call snapshot (taken under ha->lock before the tentative mutation) so the adapter's in-memory state stays consistent with the raft library's own 'deny without updating voted_for' behavior, (c) returns the negative rc so raft_on_vote_request denies the vote per its own Step 7 contract. ha->term is deliberately NOT rolled back -- confirmed via direct read of raft_on_vote_request's Step 2 (raft.c:191-204) that the raft library itself adopts a higher observed term unconditionally, before and independent of the vote-grant/persist outcome, so the adapter's ha->term correctly mirrors that same unconditional-adoption semantics. Also fixed the adjacent stale doc-comment (src/controller/CLAUDE.md's Protocol Verification Checklist item 1, found by a sibling audit dimension the same session) which incorrectly claimed term+voted_for were written 'atomically under ha->lock' -- term uses a separate atomic store outside the lock.\n\nTest: added 3 tests to testsuite/test_ha_durability.c. (1) test_persist_term_returns_error_on_write_failure -- points workdir at a path whose parent directory doesn't exist (deterministic ENOENT, portable, no permission-bit tricks needed even running as root), asserts ha_persist_term returns <0. (2) test_persist_term_null_workdir_returns_success -- regression guard that the NULL-workdir test-mode skip stays a 0/success return, not folded into the new error path. (3) test_vote_denied_and_state_rolled_back_on_persist_failure -- drives the REAL production path (ha_init_raft wiring raft_cb_persist as the real on_persist callback, then raft_on_vote_request -- the exact function cluster.c's production dispatch calls) against a minimal cluster_t/myconf_t fixture (ha_init_raft(ha, NULL, n) avoids needing a real persist_t, ha->raft_c set directly afterward -- the same test-shim pattern ha.h already documents for raft_cb_become_leader_for_test/raft_cb_become_follower_for_test) with a genuine non-empty candidate name populated so the rollback assertion is meaningful (not trivially satisfied by an already-empty baseline); asserts the vote is RAFT_DENY and ha.voted_for_term/voted_for_name are unchanged from their pre-call baseline.",
+      "tags": [
+        "controller",
+        "ha",
+        "raft",
+        "election-safety",
+        "persistence",
+        "error-handling"
+      ],
+      "related_bugs": [],
+      "occurrences": 1,
+      "last_seen": "2026-08-25T00:50:00Z"
     }
   ]
 }