Replace 38 hand-crafted UPDATE prs SET status calls across evaluate.py
and merge.py with 7 centralized functions that enforce invariants:
- close_pr: always syncs Forgejo (opt-out for reconciliation)
- approve_pr: raises ValueError on empty domain (prevents NULL bugs)
- mark_merged: always sets merged_at, clears last_error
- mark_conflict: always increments merge_failures, sets merge_cycled
- mark_conflict_permanent: terminal conflict state
- reopen_pr: handles all reopen scenarios (transient, rejection, reeval)
- start_review: atomic claim with bool return
This eliminates the class of bugs that produced 3 incidents:
1. Domain NULL on musings bypass (7 PRs stuck, 20h zero throughput)
2. Forgejo ghost PRs (70 PRs open on Forgejo but closed in DB)
3. Merge_cycled missing on various close paths
Also fixes: 3 close paths in merge.py had DB update before Forgejo call
(reversed order). close_pr does Forgejo first, then DB.
Only remaining raw status transition: _claim_next_pr (approved→merging)
which is an atomic subquery and doesn't have invariant requirements.
20 new tests, 264 total passing, 0 regressions. Net -101 lines in
evaluate.py + merge.py.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
