docs(raft-log-replication): validation GO notes + known 8.3-restart partial + adapter invariant

.kiro/specs/raft-log-replication/tasks.md

@@ -197,3 +197,9 @@
   - _Requirements: 1.1, 2.1, 3.2, 4.3, 5.1, 6.1, 7.1, 8.4_
   - _Boundary: src/lib/raft, src/lib/testsuite_
   - _Depends: 9.2, 9.3, 9.4_
+
+## Implementation Notes
+
+- **Validation (2026-06-21): GO.** Clean ASAN build green from scratch (`xce-build.sh lib`, Fail 0); 8/8 requirement sections covered (40/41 acceptance criteria); boundary ALIGNED (no controller files; no commit advance / vote freshness / transport I/O / entry-bytes in library state); out-of-scope items confirmed absent.
+- **Known minor gap — Req 8.3 "node restart while replication proceeds" (PARTIAL):** drop/dup/reorder are fully covered by 9.3, and the `initial_log_len` restore primitive is tested at init; 9.4's stale-rejoin covers the equivalent observable state. But no dedicated simulator test chains "restart a sim node mid-replication (re-init from restored log_len) then resume AE delivery" — the sim has no in-place single-node restart helper. Low risk; a follow-up could add a `raft_sim_restart_node` + test to close it strictly.
+- **Adapter invariant (from validation LOW note):** the AE accept already-have branch treats `on_get_entry_term(index) == entry_term` as a match, which is also true when both are 0. A correct leader never sends `entry_term == 0` for a real entry (`raft_log_append` stamps `s->term >= 1`), so this is safe in-library — but the controller adapter (raft-commit-safety) MUST guarantee it never delivers `entry_term == 0` with `entries_len == 1`.