Policy snapshot GC acceptance coverage

• Status: Accepted
• Date: 2026-02-21
• Context:
  • ERD_INDEXERS.md requires policy snapshot reuse via hash, transactional ref_count tracking, and garbage collection for stale snapshots.
  • Existing job-level tests already verify GC behavior and refcount repair ordering, while the latest search-request tests verify create-time reuse and retention-time decrements.
  • The Phase 9 acceptance checklist item remained open despite complete executable coverage.
• Decision:
  • Mark the acceptance item Policy snapshot reuse and GC rules match ERD complete in ERD_INDEXERS_CHECKLIST.md.
  • Keep GC/refcount verification at the data boundary using existing tests:
    • indexers::jobs::tests::job_run_policy_snapshot_gc_repairs_ref_count_before_delete
    • indexers::search_requests::tests::search_request_create_reuses_policy_snapshot_by_hash_and_increments_ref_count
    • indexers::search_requests::tests::retention_purge_decrements_policy_snapshot_ref_count
  • Alternatives considered:
    • add duplicate API-layer tests for the same behavior: rejected because stored-procedure tests already exercise authoritative behavior directly.
• Consequences:
  • Positive outcomes:
    • acceptance checklist now matches implemented and tested ERD behavior;
    • policy snapshot lifecycle remains covered at create, purge, and GC phases.
  • Risks or trade-offs:
    • if snapshot lifecycle semantics change, tests and checklist mapping must be updated together.
• Follow-up:
  • Implementation tasks:
    • Continue with the next unchecked acceptance and hard-blocker items.
  • Review checkpoints:
    • just ci
    • just ui-e2e