---
id: suite-harness-current-thread
name: Contract-suite harness — async sleep in `past_stamp_sleep`, current-thread flavor readiness
status: completed
depends_on: []
scope: narrow
risk: low
impact: component
level: implementation
tags: [wave-6, contract-suite]
---

## Description

The one suite-side change wave 6 carries
([ADR-024](../architecture/decisions/024-mem-engine.md) §5 item 4; the
review-003 posture note at `properties.rs:1683`): the suite's
`past_stamp_sleep` helper uses a blocking `std::thread::sleep` inside
async rows — safe under the multi-thread test flavors both existing
engines' targets use, but it would stall a current-thread runtime. The
mem engine's suite column **must** run under a current-thread flavor
(`#[tokio::test(flavor = "current_thread")]`) to keep the mem
engine's internals honestly current-thread-clean — which is what
wasm32 needs.

- Replace `past_stamp_sleep`'s blocking sleep with `tokio::time::sleep`
  (async). The helper's semantics are unchanged (a bounded
  pre-`run_at` settle before reads); the existing rows' determinism
  posture is untouched — verify the two legs using it re-run green on
  both engines with no timing drift (tolerances unchanged).
- Document (one line in the helper's doc comment or the factory
  contract notes) the harness posture: **no blocking calls inside
  suite rows** — the mem column enforces the flavor that catches
  violations.

This task is engine-independent and can run any time before
`mem-engine-integration` wires the third column.

## Acceptance Criteria

- [x] `past_stamp_sleep` is async (`tokio::time::sleep`)
- [x] Both engines' existing suites re-run green with identical
      assertions and tolerances (determinism posture intact)
- [x] The no-blocking-calls posture noted where the harness's
      determinism posture is documented
- [x] Clippy `-D warnings`, fmt clean; workspace gates green

## References

- docs/architecture/decisions/024-mem-engine.md §5
- docs/reviews/003-wave-5-general-review.md §Finding 5 (the
  `properties.rs:1683` posture note)
- docs/architecture/decisions/022-contract-suite-layout.md (the
  factory contract the flavor rides)

## Notes

- The posture note went into `past_stamp_sleep`'s doc comment rather
  than the factory contract notes: the posture is a harness rule about
  row internals (what a row may call), not part of the
  `StoreFactory` shape, and the doc comment sits exactly where a row
  author reaches for a sleep. The comment cites ADR-024 §5 for the
  current-thread flavor that enforces it.
- Five rows exercise the helper across its two use shapes (the
  lapse-settle legs and the scheduler runner-less-pause leg):
  `lock_ttl_expiry_and_reacquisition`, `job_handle_validity_predicate`,
  `queue_depth_reclaim_and_dead_letter`, `sweep_no_stranded_rows`,
  `scheduler_bounded_catchup`. All nine call sites gained `.await`;
  assertions and tolerances untouched.

## Summary

`past_stamp_sleep` now awaits `tokio::time::sleep` instead of blocking
on `std::thread::sleep` (alkstore-contract-suite/src/properties.rs),
making every suite row current-thread-safe for the mem engine's
`#[tokio::test(flavor = "current_thread")]` column (ADR-024 §5 item 4);
the doc comment records the no-blocking-calls-inside-rows posture.
Both engines' `contract_suite` re-ran fully green (25/25 each, SQLite
15.0 s / Postgres 21.3 s — no timing drift, tolerances unchanged); the
full workspace build, tests, `clippy -D warnings`, and `fmt --check`
pass. PostgreSQL leg ran against the POC container (`pglo-poc`, port
15432, creds per docs/reviews/003 §env note).