Review gate — wave-5 suite passed (task review-wave-5): the suite stands as the compatibility instrument and the engine specs flip to stable. All 25 mechanism rows per engine column read in full and verified against core-contract.md §Verification backlog item by item (the appendix map's every claim confirmed by the pinning row/text, incl. the combined-coverage claim for save_offset_tx exactly-once and the five engine-side pins — SQLite open row, watcher-cadence knob, M-1 sweep-rollback: SQLite trigger seam live + the pg frame's in_tx structure code-read; beyond-64 skip-forward; cap-curve); all 25 'Contract stamp:' markers checked against the cited ADR § bodies (ADR-008 §3/§5/§7/§8, 009 §1/§3/§4/§6, 010 §1-§5, 014 §1, 015 §1-§5, 016 §5, 020 §1-§4, 021 §1/§3/§4/§5, 023 §1/§2, 012 §2, 019, 007, 006) — the enqueue_opts_resolution amendment accumulation rides ADR-023 §2 per the convention; all six parked dispositions audited and recorded (M-1 engine-side, skip-forward engine-side twins, cap engine-side, fire-wake parity not demanded, lock busy-path no divergence, reconnect-success test taken); conformance spot-checks clean (no row pins beyond ADR text, determinism posture holds incl. the two documented extensions, cross-references not duplication). Green on both engines this session: workspace build/test/clippy -D warnings/fmt; SQLite column 25/25 server-less twice (isolated + concurrent); pg column 25/25 vs the harness server three full runs (two consecutive + one concurrent with the SQLite column) plus 6 focused --test-threads=6 stress runs of the two development-time flake rows — all clean, the two unreproducible pg failures recorded with the bounded investigation and a wave-6 watch flag in the task's Notes. Docs: engine-sqlite.md and engine-postgres.md frontmatter status draft → stable with dated annotations citing this gate; implementation.md wave-table row 5 and review-rounds entry; suite-opts-backoff-rows.md placeholder remnants removed. Wave 6 (release readiness) decomposition may proceed

docs/plans/implementation.md

@@ -1,6 +1,6 @@
 ---
 status: draft
-last_updated: 2026-10-10 (wave-4 fix batch landed and gate-verified — review-wave-4-fixes passed; wave 5 decomposed)
+last_updated: 2026-10-10 (wave 5 implemented and reviewed — review-wave-5 verified the discharge map, stamps, dispositions and green-on-both-engines; engine specs flipped to stable)
 ---
 
 # alkstore — Implementation plan
@@ -36,7 +36,7 @@ parallel).
 | [2](#wave-2--sqlite-substrate-fork) | honker-core fork into `alkstore-sqlite/src/substrate/`: port, deltas, provenance, test floor | wave 1 (workspace scaffold only) | implemented + reviewed (2026-10-08) |
 | [3](#wave-3--sqlite-engine) | SQLite engine: connection architecture, re-derived queue ops on contract v1, scheduler/outbox, tx seam, SQLite backlog column | waves 1 + 2 | implemented + reviewed (2026-10-08) |
 | 4 | [Postgres engine](#wave-4--postgres-engine): schema bootstrap, pool/open, listener/forwarder, all mechanisms, tx seam, pg backlog column | wave 1 | implemented + reviewed (2026-10-08) |
-| 5 | [Contract suite](#wave-5--contract-suite): the cross-engine equivalence properties (core-contract.md §Verification backlog), version-stamped per ADR-017 | waves 3 + 4 | decomposed (2026-10-10) |
+| 5 | [Contract suite](#wave-5--contract-suite): the cross-engine equivalence properties (core-contract.md §Verification backlog), version-stamped per ADR-017 | waves 3 + 4 | implemented + reviewed (2026-10-10) |
 | 6 | Release readiness: crate docs, deployment matrix final pass, README (written last, honestly), publish prep; mem-engine and fuzzing decisions | wave 5 | not yet decomposed |
 
 ## Wave 1 — Foundations
@@ -324,6 +324,24 @@ decomposes. Specific gates:
   `tasks/review-wave-4.md`) and making `tx_publishes_compose_with_the_handle`
   deterministic (20 consecutive solo runs green); the remaining fixes
   ride the wave-4 fix-batch decomposition below.
+- **Wave 5 review gate** (`review-wave-5`, 2026-10-10) — the suite as
+  compatibility instrument, gate passed: the backlog discharge map
+  verified row-by-row against the pinning tests (all 25 mechanism rows
+  per column stamped, wiring confirmed in both engines' suite targets;
+  the engine-side pins — SQLite open row, watcher-cadence knob, M-1
+  sweep-rollback (SQLite trigger seam + the pg frame's code-read),
+  beyond-64 skip-forward, cap-curve — read and confirmed); stamps
+  cross-checked against the cited ADR § texts (the
+  `enqueue_opts_resolution` amendment accumulation rides ADR-023 §2 per
+  the convention); parked dispositions audited (all six recorded;
+  scheduler fire-wake parity left as-is, the lock busy-path answered
+  with no divergence); green on both engines (SQLite server-less; pg
+  vs the harness server, three full runs incl. one concurrent with the
+  SQLite column, plus focused stress). Engine specs flipped to
+  `stable`. Two unreproducible pg row failures from development were
+  recorded in the task's Notes (both rows' assertions are
+  state-outcome-shaped; flagged for watch, not blocking the gate) —
+  see `tasks/review-wave-5.md` §Notes.
 - **Wave 5 decomposition** (2026-10-10) — audit-first: the engines'
   backlog columns already discharge most of the §Verification backlog
   (map recorded in `tasks/review-wave-5.md`'s appendix for the gate to