---
id: review-wave-3
name: Wave 3 review gate — the sqlite engine vs the contract
status: pending
depends_on: [suite-column-sqlite]
scope: narrow
risk: low
impact: phase
level: review
tags: [wave-3, review]
---

## Description

The wave-3 review gate — the engine-wave review shape
(docs/plans/implementation.md §Review gates: "engine-vs-contract
conformance"), before wave 4 decomposes. The gate reads the
implementation against the pinned ADR text line by line (the wave-1/2
gates' method).

Gate checks:

- **Engine-vs-contract conformance**: the suite column green
  server-less; the engine-state window family contract-tested per its
  applicability row (ADR-012 §5's table — window family yes, pin
  clauses no, sweep-lock body no); virgin-store semantics including
  the no-tables-yet form; the `size` metadata-only discipline (the
  indexed column probe never loads the value blob).
- **The sqlite posture vs ADR-003/007**: WAL + `synchronous=NORMAL`
  as the shipped durability tier; the single-writer ceiling documented
  as posture, not hedged (REQ-1's economics); prepared-statement
  discipline; `has` as an EXISTS probe; the B5 row shape (key/value/
  size); bounded reads.
- **The durable-window sweep vs ADR-008 §2 / ADR-012 §5/§6.7**:
  candidates staged at `visible_after = mark_end + window` (the
  constructor-tunable delay, shipped default 5 min); the executor is
  the next sweep; execution-time re-arbitration; report counts exact
  relative to the schedule; the inline form preserved verbatim for
  non-SQL engines; the single-node posture unchanged (pins/liveness/
  arbitration lock in-process — only the window's persistence is
  engine rows); the one-window-host posture recorded.
- **The seam reduction honored**: no pin rows, no sweep-lock body
  anywhere in the sqlite engine (dead machinery per ADR-012 §5);
  `ensure_gc_schema` creates `gc_window` only; the embedder's
  liveness table never created by the engine.
- **Blocking discipline**: all rusqlite work off the async path
  (`spawn_blocking`); no blocking I/O under internal locks; the
  connection posture recorded.
- **Named design points audited as resolved** (each recorded in its
  task's Notes): the connection posture; the timestamp encoding;
  schema-creation timing vs the no-tables-yet tolerance; the kv cursor
  dispatch shape over multiple kv engines; the protect-consult posture
  on overdue execution; the delay-0 test tuning's legality.
- **Family conventions**: no comments in code (doc comments on public
  API fine), thiserror, tokio-only async, no unwrap/expect outside
  tests, naming, one-module-per-file re-export shape, the
  `#![allow(dead_code)]` scope notes matching their remaining scope.
- **Gates green**: `cargo test` (default — the sqlite column runs
  here), `cargo test --features mem`, `cargo test --all-features`,
  `cargo clippy --all-targets -- -D warnings`,
  `cargo clippy --all-features --all-targets -- -D warnings`,
  `cargo fmt --check`.

Findings are fixed inline where cheap, or recorded as wave-4
amendments where they shape the next decomposition. The gate's
completion is what unblocks wave 4's decomposition.

## Acceptance Criteria

- [ ] Every gate check above read and verified against the cited ADR
      text (not from memory of it)
- [ ] Named design points each decided, recorded, and consistent with
      the specs
- [ ] Findings fixed inline or recorded as wave-4 amendments with
      owners
- [ ] All gates re-run green after any fixes
- [ ] Wave 4 decomposition unblocked (recorded in this task's Summary)

## References

- docs/plans/implementation.md (§Wave 3, §Review gates — engine wave reviews)
- docs/architecture/decisions/003-backend-contract-and-dispatch.md
- docs/architecture/decisions/007-two-kv-engines-sqlite-and-postgres.md
- docs/architecture/decisions/008-trait-size-probe-fleet-gc-and-large-engines.md §2
- docs/architecture/decisions/010-backend-io-seams-and-fleet-state.md §2
- docs/architecture/decisions/012-pre-decomposition-consistency-rulings.md §1/§5/§6.7
- docs/architecture/store-api.md
- tasks/review-wave-2.md (the gate method)

## Notes

> To be filled by the review agent

## Summary

> To be filled on completion