review-wave-6 — the wave-6 gate passes, engine-mem.md flipped to stable

The born-pinned gate audited the mem engine against the contract and
ADR-024: the conformance read clean in mechanism substance (queue
state machine, scheduler collapse, outbox, streams, locks, clock,
validation, tx overlay, wake substrate — incl. a full guard-order and
panic-hygiene audit); the suite's third column read row-by-row and
25/25 green under the per-test current-thread flavor (24 engine-shared
rows + mem's payload_too_large non-occurrence arm + the factory-shape
test); three-way arithmetic equivalence green on all columns; the
wasm32 acceptance items verified (compile-clean, tokio sync+time,
no blocking, flavor enforced); the rider's two arms verified (Finding
1 discharged; Findings 2-3 stay parked for wave 7); workspace gates,
taskgraph validate green.

Three edge-domain fixes landed inline: the stream cursor read's
i64::MAX overflow (Bound::Excluded), trim_to's i64::MAX horizon
endpoint (Bound::Included), and the scheduler register path now
rejecting a parseable interval whose first boundary overflows with
InvalidSpec — the one engine-vs-engine divergence the read found,
aligned into the class-1 window — plus a pinning test and scaffold-
residue doc/comment cleanups (clock allows, tx per-stream wake
comment, wakes/stream module docs). Recorded findings with
dispositions in the task's Notes for the wave-7 pre-release pass:
the multi-thread publish-to-wake ordering tolerance, the heartbeat/
save_offset/EventReceiver-try_recv ADR-023 §2 classification gaps,
and the mem arithmetic being a suite-pinned transplant.

Verified: cargo build; cargo test --workspace green (mem 101 lib +
25 suite, sqlite 191+25, pg 124+25+9 server-less, core 25, harness 3);
clippy --all-targets -D warnings clean; fmt clean; taskgraph validate
(61 tasks). Gate record: tasks/review-wave-6.md (Notes + Summary),
implementation.md wave-6 row + review-rounds entry.

docs/architecture/engine-mem.md

@@ -1,9 +1,13 @@
 ---
-status: implementation-complete
-last_updated: 2026-10-10 (the wave-6 wave landed: the full surface
-wired over guarded state, the suite's third `StoreFactory` column
-green on the host under the current-thread flavor, the wasm32
-compile gate clean — the review gate holds the stable flip)
+status: stable
+last_updated: 2026-10-10 (the wave-6 review gate passed: the
+conformance read clean — three edge-domain fixes landed inline (the
+stream cursor read's `i64::MAX` overflow, `trim_to`'s horizon
+endpoint, the scheduler register-time interval overflow now rejecting
+with `InvalidSpec` like the SQLite register) plus scaffold-residue
+cleanup; the third column's 25-row set green under the current-thread
+flavor; the wasm32 gate + feature subset verified; the rider's arms
+verified)
 ---
 
 # Mem engine