pr-gates

# PR Gates ## Mandatory Flow 1. Run `just preflight` before finalizing changes. 2. Run `just gate-pr` before pushing or updating a PR. 3. If the same command fails twice in one session, stop rerunning and switch to root-cause debugging. 4. Do not push when any gate is red. ## Review Feedback Closure For every P1/P2 review finding, include all three: - Code change reference (file path and concise rationale) - Targeted verification command - Pass/fail evidence from that command ## Async And Stateful Changes When touching worker lifecycle, cancellation, retries, state transitions, or caches: - Document terminal states and allowed transitions. - Explicitly reason about race windows and idempotency. - Run targeted tests in addition to broad gate runs. - Capture the exact command proving the behavior. ## Migration Safety - Never edit an existing file in `migrations/`. - Add a new timestamped migration for every schema change. - If a gate flags migration edits, stop and create a new migration file. ## Handoff Format - Summary - Changed files - Gate commands executed - P1/P2 finding-to-evidence mapping - Residual risk