mem engine scheduler/outbox — coverage reconciliation against the seam task's foundation with the one unpinned posture (mem-engine-scheduler-outbox): run_once issues no engine-issued heartbeat in delivery — the handover carries the raw claim deadline and the boxed JobHandle's own heartbeat stays available to the closure (renewal is the consumer's obligation). All other pins (boundary fire determinism, 64-cap catch-up + grid-honest skip-forward, no-double-fire, leadership contention/loss/clean-stop/lease-release, validation + @every grammar matrix, outbox ack/retry curve + derived name + unreachability) verified already present in scheduler.rs/outbox.rs's suite. No production code changed; tests only (+1 + fixture widening, mem suite at 100). Task file: status completed, Notes/Summary filled

alkstore-mem/src/outbox.rs

@@ -155,6 +155,8 @@ mod tests {
     struct RecordingDelivery {
         saw_payload: Option<Vec<u8>>,
         stamps: Option<(i64, i64, i64, Option<i64>)>,
+        handover_deadline: Option<i64>,
+        manual_heartbeat: bool,
         outcome: Option<Result<()>>,
     }
 
@@ -163,6 +165,8 @@ mod tests {
             Self {
                 saw_payload: None,
                 stamps: None,
+                handover_deadline: None,
+                manual_heartbeat: false,
                 outcome: Some(outcome),
             }
         }
@@ -182,8 +186,18 @@ mod tests {
                 j.backoff_base_s,
                 j.dead_letter_retention_s,
             ));
+            self.handover_deadline = j.claim_expires_at;
+            let beat = self.manual_heartbeat;
             let outcome = self.outcome.take().unwrap_or(Ok(()));
-            Box::pin(async move { outcome })
+            Box::pin(async move {
+                if beat {
+                    assert!(
+                        job.heartbeat(600).await.unwrap(),
+                        "the boxed JobHandle's own heartbeat stays available to the closure"
+                    );
+                }
+                outcome
+            })
         }
     }
 
@@ -287,6 +301,37 @@ mod tests {
         assert!(dead.died_at == 2_000 || dead.died_at > 0);
     }
 
+    #[tokio::test(flavor = "current_thread")]
+    async fn run_once_issues_no_engine_heartbeat_in_delivery() {
+        let store = MemStore::new();
+        store.clock.freeze(1_000);
+        let mut ob = outbox(&store, "mail");
+        ob.enqueue(serde_json::json!(1), EnqueueOpts::default())
+            .await
+            .unwrap();
+        let mut delivery = RecordingDelivery::with(Ok(()));
+        assert!(ob.run_once("w1", &mut delivery).await.unwrap());
+        assert_eq!(
+            delivery.handover_deadline,
+            Some(1_060),
+            "handover carries the raw claim deadline — \
+             run_once issues no engine-side renewal for the closure"
+        );
+        assert!(store.state.queues.guard().live.is_empty(), "Ok ⇒ ack");
+        let id = ob
+            .enqueue(serde_json::json!(2), EnqueueOpts::default())
+            .await
+            .unwrap();
+        let mut renewal = RecordingDelivery::with(Ok(()));
+        renewal.manual_heartbeat = true;
+        assert!(ob.run_once("w2", &mut renewal).await.unwrap());
+        assert!(
+            store.state.queues.guard().live.is_empty(),
+            "renewal inside the window is the closure's obligation — \
+             and the boxed handle's heartbeat carries it ({id} acked)"
+        );
+    }
+
     #[tokio::test(flavor = "current_thread")]
     async fn empty_worker_id_is_invalid() {
         let store = MemStore::new();

tasks/mem-engine-scheduler-outbox.md

@@ -1,7 +1,7 @@
 ---
 id: mem-engine-scheduler-outbox
 name: Mem engine — scheduler (`schedule`/`unschedule`/`run_schedules`) and outbox helper
-status: pending
+status: completed
 depends_on: [mem-engine-queues, mem-engine-locks]
 scope: moderate
 risk: medium
@@ -56,16 +56,16 @@ derived-name format.
 
 ## Acceptance Criteria
 
-- [ ] Scheduler surface + tick: boundary fire, catch-up (≤64),
+- [x] Scheduler surface + tick: boundary fire, catch-up (≤64),
       skip-forward — unit-pinned with tokio-time determinism
-- [ ] Leadership contention through the `__alkstore_scheduler` lock;
+- [x] Leadership contention through the `__alkstore_scheduler` lock;
       `LeadershipLost` on loss, `Ok(())` on clean stop — pinned
-- [ ] Schedule name + queue argument validation; `@every`-only parser
+- [x] Schedule name + queue argument validation; `@every`-only parser
       (cron → `InvalidSpec`) — pinned
-- [ ] Outbox: `enqueue`/`run_once` semantics (no engine heartbeat);
+- [x] Outbox: `enqueue`/`run_once` semantics (no engine heartbeat);
       derived backing-queue name format identical to both engines —
       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
@@ -80,8 +80,65 @@ derived-name format.
 
 ## Notes
 
-> To be filled by implementation agent
+> Filled by implementation agent, 2026-10-10.
+
+1. **The implementation already landed in the seam task** — the same
+   all-or-nothing trait-impl disposition the previous wave-6 mechanism
+   tasks recorded: the scheduler (`scheduler.rs`'s register table,
+   `run_tick`, the runner) and the outbox helper (`outbox.rs`) were
+   implemented with the seam's whole-engine scope; this task found its
+   mechanisms *implemented*.
+2. **Coverage reconciliation**: already pinned by the seam suite —
+   the boundary-fire row (deterministic `run_tick` fires, ready-at-
+   fire-instant rows stamped with the registered values + plain
+   defaults, no-double-fire floor, fire+advance as one guarded op),
+   the bounded-catch-up row (600 s behind → exactly 64 fires, never
+   300; skip-forward lands the next boundary strictly future with the
+   grid honest; never-due schedules untouched), the leadership rows
+   (two contenders through the `__alkstore_scheduler` lock: one wins,
+   the loser `Err(LeadershipLost)`; a blocked lock loses before any
+   fire; clean stop → `Ok(())` and the lease released for the next
+   runner), the register rows (upsert-by-name + stamp resolution +
+   read-back; both name-bearing arguments validated + cron rejected
+   pre-storage with nothing written; the `@every` grammar matrix),
+   `unschedule` (removal + absent-false + reserved-name rejection),
+   `fired_rows_are_ordinary_queue_work` (the fire claims through the
+   ordinary queue), the outbox rows (Ok ⇒ ack / Err ⇒ retry with the
+   queue's equal-jitter curve and the delivery error riding the
+   exhaust path onto the dead row; the derived 60/5/5 stamps with
+   `max_attempts` the one override; no-work `Ok(false)`; empty
+   `worker_id` rejected), and the derived backing-queue name format +
+   `enqueue_tx` unreachability.
+3. **What this task added** — the one unpinned posture from the
+   description: `run_once_issues_no_engine_heartbeat_in_delivery` —
+   the handover carries the raw claim deadline (no engine-side
+   renewal before or inside delivery), and the boxed
+   [`JobHandle`]'s own `heartbeat` remains available to the closure
+   (renewal is the consumer's obligation, ADR-019 §5). The delivery
+   fixture grew `handover_deadline` + a manual-heartbeat arm for it.
+4. **No production code changed** — verified correct as-found; tests
+   only (+1 in `outbox.rs`, fixture widened, 100 mem tests total).
+   The scheduler's boundary waits ride realtime tokio time with
+   stamps on the engine clock; the tick/catch-up/leadership pins
+   drive the crate-internal `run_tick`/`run_schedules` directly, so
+   determinism holds without realtime waits.
 
 ## Summary
 
-> To be filled on completion
+> Filled on completion, 2026-10-10.
+
+Completed the mem engine's scheduler/outbox task against the seam
+task's foundation: reconciled the description's pin list against
+`alkstore-mem/src/scheduler.rs` + `outbox.rs`'s existing suite (14
+pre-existing tests), found every tick/catch-up/leadership/validation/
+outbox shape already pinned, and added the one gap — the
+no-engine-issued-heartbeat posture pinned end-to-end (raw claim
+deadline at handover; the closure's own heartbeat path available and
+honored). Acceptance criteria: scheduler surface + tick determinism ✓
+(seam rows), leadership ✓ (seam rows), validation + grammar ✓ (seam
+rows), outbox semantics + derived name format ✓ (seam rows + the new
+heartbeat row), gates ✓. Verified: `cargo test -p alkstore-mem`
+100/100 (99 + 1 new, new test green solo), 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.