Deterministic (no-LLM) sub-gate on the deploy-staging -> deploy edge that
catches a feature branch up to the CURRENT origin/main, re-tests the combined
tree, and serialises merges with a per-repo file lease — so two green parallel
branches can no longer break main (self-hosting safety for the orchestrator repo).
- src/merge_gate.py: branch_is_behind_main, auto_rebase_onto_main (push
--force-with-lease ONLY the task branch, NEVER main), retest_branch, and a
file merge-lease (atomic O_CREAT|O_EXCL, holder-aware release, stale reclaim).
Strict never-raise contract; all git ops in the per-branch worktree.
- src/qg/checks.py: check_branch_mergeable composes the primitives under the
lease; registered in QG_CHECKS. Conditional rollout (merge_gate_enabled /
merge_gate_repos, default self-hosting only).
- src/stage_engine.py: sub-gate hook on deploy-staging (not a new stage). PASS ->
advance; "merge-lock busy" -> DEFER (re-queue with available_at, anti-deadlock
at max_concurrency=1, capped); conflict/red re-test -> rollback to development
+ developer retry (capped by MAX_DEVELOPER_RETRIES). Lease released on
deploy->done / rollback / PR-merged webhook.
- src/db.py: enqueue_job(available_at_delay_s=...) for the defer (no schema change).
- src/webhooks/gitea.py: holder-aware lease release on PR-merged.
- src/config.py + .env.example: ORCH_MERGE_* settings.
Docs: README + adr-0006 (architect) already cover the design; CHANGELOG updated.
Tests: test_merge_gate.py, test_qg_merge_gate.py, test_merge_gate_race.py,
test_stage_engine.py::TestMergeGate, test_config.py, QG-registry snapshot.
Full suite: 535 passed.
Refs: ORCH-043
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
