---
id: pg-fix-scheduler-tick-seam
name: "pg scheduler — transient-fault tick seam: retry/exhaustion arms tested (review 003 Finding 1)"
status: pending
depends_on: []
scope: narrow
risk: low
impact: component
level: implementation
tags: [wave-6, postgres-engine, scheduler, test-hardening]
---

## Description

Review 003 Finding 1 (MEDIUM — `docs/reviews/003-wave-5-general-review.md`):
the pg scheduler's transient-error retry loop
(`alkstore-postgres/src/scheduler.rs:680-704`, `tick_with_retries`)
has never executed under any test — `pg-fix-scheduler-resilience`
pinned its *constants* (`the_tick_retry_policy_is_pinned`) but the
loop that uses them (retry, backoff sleeps, exhaustion error, the
`eprintln` diagnostic — lcov 171-184, 237-260) is dead code under
test, with no fault seam anywhere in the pg scheduler for `tick_once`.
This is the last uncovered hardening arm from the wave-4 fix batch,
and the exact class that produced review 002's live bugs.

Fix shape (the review's recommendation): a `cfg(test)` transient-
fault seam on the pg tick path, following the `sqlite-commit-error-arm
` precedent — a one-shot armed flag feeding a fabricated
transient error into the *real* retry loop (never a replica):

- (a) one retried tick then success: the seam faults once, the next
  `tick_once` succeeds, the job processes — the retry + backoff-sleep
  arms execute for real;
- (b) exhaustion: the seam faults the max retry count, the loop
  exhausts to the typed error shape and the `eprintln` diagnostic
  fires, the runner survives (the resilience property the fix
  promised).

Cross-test safety is per-store scoping (the commit-fault seam's
pattern); no production-path changes — the seam is cfg-gated, born
disarmed, consumed-on-use.

## Acceptance Criteria

- [ ] The seam lands cfg(test)-gated; the real `tick_with_retries`
      executes under test (no loop replication)
- [ ] Arms (a) and (b) pinned as above; the runner survives
      exhaustion
- [ ] `cargo test -p alkstore-postgres` green against the harness
      server; skips clean server-less
- [ ] Clippy `-D warnings`, fmt clean; workspace gates green

## References

- docs/reviews/003-wave-5-general-review.md §Finding 1 (sites, lcov
  inventory, recommendation)
- docs/architecture/decisions/024-mem-engine.md (the wave-6 window
  this rider rides — the plan's wave-6 section, "Riding the window")
- tasks/sqlite-commit-error-arm.md (the seam pattern of record)
- tasks/pg-fix-scheduler-resilience.md (the constants the loop uses)

## Notes

> To be filled by implementation agent

## Summary

> To be filled on completion