[asselstine]

Refs GEN-2907

Checkpoint delivered on this continuation

• Added identifier-free backlog metrics for runs waiting on finalization, lifecycle handoff, webhook processing, and GitHub verification, with oldest-age signals for dashboard panels.
• Documented the added queue panels and alert coverage in the retention runbook.
• No production inventory refresh, purge, or deployment occurred.

Validation on f8eeae8d00a158cbc204c7d0497cbe2dee0e8eb8

• Node 24.12.0 / npm 11.19.0; npm ci; isolated local PostgreSQL bootstrap.
• Focused retention tests passed (10 tests); backlog query executed successfully against the isolated database.
• Full root npm test passed: backend 92 files (603 passed/5 skipped); generated contracts and app build; compiled app/API/PostgreSQL integration (2 passed); Worker/runtime checks; Chromium functional checks (7 passed); app unit checks (103 passed/1 skipped); proxy checks.
• No production/shared database was used.

Remaining acceptance work

• Continue remaining provider, finalization, lifecycle, replay, webhook race/failure coverage and broader UI lifecycle acceptance.
• Refresh and read-only verify historical cleanup cohorts, including the five no-handle cases, using the documented authorized production audit path.
• Complete staged rollout evidence after that refresh. Do not run a production purge or deployment.

GEN-2913 remains the verified Backlog blocker for the audit path and scope. Keep GEN-2907 In Progress and this PR draft until all acceptance gates and final validation pass. GitHub Build Manager owns asynchronous PR check and merge-queue monitoring.

[linear]

GEN-2907