Wave-4 review gate: conformance code-read clean (0 findings) — forwarder/seam integrity, ADR-023/016 follow-through, backoff + boundary math vs ADR text, schema posture, 10-row backlog column green against the harness server; the flagged tx-compose flake reproduced twice, root cause unresolved, recorded as F-1 for wave 5's suite hardening + three no-action notes (task review-wave-4)

docs/plans/implementation.md

@@ -1,6 +1,6 @@
 ---
 status: draft
-last_updated: 2026-10-08 (wave 4 decomposed — 11 tasks; waves 1–3 implemented + reviewed)
+last_updated: 2026-10-08 (wave 4 implemented + reviewed — flake F-1 recorded for wave 5; wave 5 next)
 ---
 
 # alkstore — Implementation plan
@@ -35,7 +35,7 @@ parallel).
 | [1](#wave-1--foundations) | Workspace scaffold; core crate (errors, value types, full trait surface); contract-suite scaffold | — | implemented + reviewed (2026-10-08) |
 | [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 | decomposed (11 tasks) |
+| 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: the cross-engine equivalence properties (core-contract.md §Verification backlog), version-stamped per ADR-017 | waves 3 + 4 | not yet decomposed |
 | 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 |
 
@@ -240,6 +240,12 @@ decomposes. Specific gates:
   the writer-slot error-arm stranding in
   `with_writer`/`begin`/`commit`); two minor notes deferred to
   wave 5/6 (reader-pool close path, commit-error-arm coverage).
+- **Wave 4 review gate** (`review-wave-4`) — engine-vs-contract
+  conformance code-read clean (0 findings); the flagged
+  `tx_publishes_compose_with_the_handle` flake reproduced twice and
+  recorded as F-1 (test-infra, wake-subscription under load — root
+  cause unresolved; candidate dispositions in the task's Notes for
+  wave 5's suite hardening); three no-action notes (F-2..F-4).
 - **Wave 4 decomposition** (2026-10-08) — shaped as wave 3's
   structural twin; wave-3 outcomes absorbed (constructors exist;
   arithmetic re-owned per engine; per-engine `@every` parser;