---
id: mem-doc-growth-outbox-notes
name: Pin mem's growth postures and outbox semantics in the spec (review 004 items 10+11)
status: pending
depends_on: []
scope: narrow
risk: trivial
impact: isolated
level: implementation
tags: [review-004-fixes, mem-engine, docs]
---

## Description

Two recorded mem postures get their doc pins, per
`docs/reviews/004-pre-release-general-review.md` §"Findings recorded,
not fixed" items 10 and 11 (the review's "carry into the mem spec's
growth section when next touched" — this is that touch).

**(a) Growth postures (item 10)** — two honest sentences in
`engine-mem.md`'s growth section:
- The subscribe path drains the full backlog into the receiver's
  pending deque before the first yield, and pending grows at publish
  rate for a stalled consumer (`stream.rs:314-331` — the documented
  "drains to the tail then parks" shape, unbounded on the consumer
  side).
- The claim path is an O(total-live-rows) scan with full-row clones
  per claim (`queue.rs:122-181`) — blessed economics for the ephemeral
  tier.

**(b) Outbox outcome swallow (item 11)** — `outbox run_once` drops the
ack/retry row-refs' booleans and returns `Ok(true)` even when delivery
outlived the visibility window and nothing landed (`outbox.rs:104-122`).
Inherent to the no-heartbeat outbox design (at-least-once reclaim is
the recovery). Pin the "processed means delivered-or-reclaimable"
semantic with a doc sentence in `engine-mem.md`'s outbox section; add
the `debug_assert!` too if it adds value without noise — the review
offered either, implementer's call (record which and why).

Doc-only plus at most one `debug_assert!` — no behavioral change.

## Acceptance Criteria

- [ ] `engine-mem.md` carries the two growth-posture sentences,
      anchored to the code sites
- [ ] The outbox "processed means delivered-or-reclaimable" semantic
      is pinned (doc sentence; `debug_assert!` per the recorded call)
- [ ] Doc gate green (`RUSTDOCFLAGS="-D warnings" cargo doc
      --no-deps`); mem tests green (the `debug_assert!` arm, if added,
      exercised by an existing outbox test)

## References

- docs/reviews/004-pre-release-general-review.md §"Findings recorded,
  not fixed" items 10–11 (the findings, the blessed-economics framing)
- docs/architecture/engine-mem.md (the growth section, the outbox
  section)
- alkstore-mem/src/stream.rs:314-331, queue.rs:122-181,
  outbox.rs:104-122 (the anchored sites)

## Notes

> To be filled by implementation agent

## Summary

> To be filled on completion