mem engine locks — pure reconciliation: the TTL-registry mechanism landed implemented with the seam task's whole-engine scope, and every pin the task enumerates already exists in lock.rs's suite (contention/loser-None, duration guards on try_lock+renew, silent lapse + re-acquire + renew-past-expiry refused via the frozen clock, release shapes, entry validation, no-lock_tx) — zero code, zero tests changed; the task is the disposition of record (task file status + Notes/Summary)

tasks/mem-engine-locks.md

@@ -1,7 +1,7 @@
 ---
 id: mem-engine-locks
 name: Mem engine — named locks (in-memory TTL registry)
-status: pending
+status: completed
 depends_on: [mem-engine-seam-tx]
 scope: narrow
 risk: low
@@ -37,14 +37,14 @@ The named-locks mechanism over an in-memory TTL registry
 
 ## Acceptance Criteria
 
-- [ ] `try_lock`/`renew`/`release` over the TTL registry; entry
+- [x] `try_lock`/`renew`/`release` over the TTL registry; entry
       validation (names + duration guard) — pinned
-- [ ] TTL expiry: silent lapse, re-acquisition, renew-past-expiry
+- [x] TTL expiry: silent lapse, re-acquisition, renew-past-expiry
       refused — pinned (clock-controlled tests via the state core's
       clock accessor)
-- [ ] Concurrent-contention shape: loser is `None`, winner's lease
+- [x] Concurrent-contention shape: loser is `None`, winner's lease
       intact — pinned
-- [ ] `cargo check --target wasm32-unknown-unknown -p alkstore-mem`
+- [x] `cargo check --target wasm32-unknown-unknown -p alkstore-mem`
       clean; workspace gates green
 
 ## References
@@ -58,8 +58,51 @@ The named-locks mechanism over an in-memory TTL registry
 
 ## Notes
 
-> To be filled by implementation agent
+> Filled by implementation agent, 2026-10-10.
+
+1. **The implementation already landed in the seam task** —
+   `mem-engine-seam-tx` Note 1 (the all-or-nothing trait-impl
+   disposition, the same one the notify-listen and queues twins
+   recorded): the `MemLock` registry mechanism in
+   `alkstore-mem/src/lock.rs` was implemented with the seam's
+   whole-engine scope; this task found its mechanism *implemented*.
+2. **Full coverage reconciliation — zero new tests needed**: every
+   shape the description and the three acceptance criteria enumerate
+   was already pinned by the seam suite in `lock.rs`: the contention
+   shape (first wins, loser `None` as a clean value, same-owner
+   re-grant without a second lease row — `contention_grants_once_and_
+   the_loser_reads_none`), the duration guard (`ttl <= 0` → opaque
+   `Database` `Err` on both `try_lock` and `renew`, ADR-023 §2's
+   durations kind — `duration_guards_reject_non_positive_ttls`), the
+   TTL expiry row via the frozen clock (in-TTL refusal, silent lapse,
+   re-acquisition, old-holder renew refused — `expiry_lapses_silently_
+   and_reacquires`), renew-past-expiry refused + the new holder's
+   clean life (`renew_past_expiry_is_refused`), the release shapes
+   (held-true, past-expiry-still-the-holder's, re-acquired-elsewhere
+   no-op — `release_shapes`), entry validation (empty/blank/reserved
+   name, empty owner — `entry_validation`), and the
+   locks-are-not-tx-scoped posture (the overlay neither sees nor
+   stages locks — `locks_are_not_tx_scoped`). Note also the seam
+   task's recorded semantis delta (seam Notes 7): mem pins
+   renew-past-expiry *refused*, where the SQLite substrate would
+   revive a not-yet-purged lapsed row — the stricter, contract-honest
+   arm.
+3. **No production code changed and no test changed** — the task is a
+   disposition: the surface was verified correct as-found.
 
 ## Summary
 
-> To be filled on completion
+> Filled on completion, 2026-10-10.
+
+Completed the mem engine's locks task as a pure reconciliation: the
+TTL-registry mechanism landed with the seam task's whole-engine scope,
+and the reconciliation against the description's pin list found all
+three acceptance criteria's shapes already unit-pinned in
+`alkstore-mem/src/lock.rs`'s seven tests (contention/loser-None,
+duration guards on both entry kinds, clock-controlled silent lapse +
+re-acquisition + renew-past-expiry refused, release shapes, entry
+validation, no-`lock_tx`). No code and no tests changed; acceptance
+criteria satisfied as-found. Verified: `cargo test -p alkstore-mem`
+green, workspace `cargo test` green, `cargo clippy --all-targets --
+-D warnings` clean, `cargo fmt --check` clean,
+`cargo check --target wasm32-unknown-unknown -p alkstore-mem` clean.