# RM-03 — CI Queue Guard Repair

- **Task:** RM-03
- **Issue:** #1019
- **Branch:** `fix/rm-03-queue-guard`
- **Owner:** coder-mos1
- **Reviewer:** rev-974 (independent; author != reviewer)
- **Started:** 2026-08-01

## Objective

Repair the mandatory CI queue guard so it reads provider payloads, blocks asserted non-green CI, distinguishes provider unavailability from a real non-green result, and inspects the branch actually being pushed or merged.

## Constraints

- Worktree only: `/home/hermes/agent-work/rm-03`; never mutate `/src/mosaic-stack`.
- JSON payload travels through stdin; never argv. Large payload must remain below no ARG_MAX dependency.
- TDD is mandatory. Every behavior case must be observed red before implementation.
- No bypass flags or hook suppression.
- Do not cite the existing guard's green as evidence; D-23 establishes it is zero-information.
- Gate-ready is a frozen exact head. Any push after a merge-gate verdict voids that verdict.
- No merge: coordinator holds the merge hand pending Jason.

## Design

1. Feed JSON to `python3 -c` on stdin, including pending-context rendering.
2. Classify valid green as `READY`; pending/failure/no-status/malformed/mixed as `ASSERTED_NOT_READY`; provider/credential/transport inability as `CANNOT_ASSERT`.
3. `ASSERTED_NOT_READY` exits nonzero. `CANNOT_ASSERT` emits a loud diagnostic and appends a local JSONL audit record. Push degrades to exit 0; merge holds with distinct retryable exit 75 until provider recovery, then self-clears without manual reset. Inability to write the audit exits nonzero.
4. Derive the current branch when `-B` is omitted. The merge wrapper passes the exact PR head branch, repository, and full commit SHA—not its `main` base—so fork PRs cannot resolve against an adjacent base-repository branch.

## Test matrix

| Case | Required outcome |
| --- | --- |
| success | exit 0; terminal-success |
| pending | nonzero after bounded timeout |
| failure | nonzero |
| no-status | nonzero |
| malformed | nonzero |
| >=150 KiB payload | unchanged classification; never rc126 |
| provider unreachable on push | loud audited CANNOT_ASSERT; degraded exit 0 |
| provider unreachable on merge | loud audited CANNOT_ASSERT; retryable exit 75/HOLD |
| audit unavailable | nonzero |
| implicit push branch | provider URL uses checked-out feature branch |
| merge wrapper | queue guard receives exact PR head branch/repository/full SHA |

## RED-first evidence

Observed against the unmodified `origin/main` implementation before source edits:

- `bash packages/mosaic/framework/tools/git/test-ci-queue-wait-tristate.sh` → rc 1 with 15 failed assertions.
- Success payload was reported `state=unknown`.
- Pending, failure, no-status, and malformed payloads each exited 0 and omitted `ASSERTED_NOT_READY`.
- The 160 KiB payload produced rc 141 because Python never consumed the pipe; it did not classify success.
- Provider-unreachable exited 7 with no `CANNOT_ASSERT` audit record.
- Implicit push queried `/branches/main`, not `/branches/fix/rm-03-fixture`.
- Audit-unavailable emitted no audit diagnostic.
- A credential-resolution hard-block mutant was then run before trusting that added case: `credential-unresolvable` returned rc 1 and omitted `CANNOT_ASSERT`; the matrix returned rc 1 with two named assertion failures.
- Review-blocker controls were observed red: structurally invalid `statuses` string and null-entry payloads each exited 0 as `terminal-success`; unsupported-platform discovery exited 1 without diagnostic or audit (seven named assertion failures total).
- After the push/merge asymmetry ruling, merge-side provider unavailability was observed red at rc 0; its registered case required distinct retryable rc 75.
- Aggregate `state=success` with zero contexts was observed red: it exited 0 as `terminal-success`; the registered case requires `no-status`/nonzero.
- Fork/exact-head controls were observed red: `pr-merge.sh` omitted the fork repository and full SHA, and an ignored-arguments mutant re-resolved through `/branches/` instead of the exact fork commit (two named failures).
- GitHub check-run-only success/pending/failure were each misclassified as `no-status`; the RED run had five named failures and proved the Checks API was never queried.
- The first merge-pin control was unrunnable because one `local` declaration referenced a variable before assignment under `set -u`; this was disclosed and corrected rather than counted. The runnable RED then showed Gitea payload `{"Do":"squash"}` lacked `head_commit_id`; a separate GitHub run showed `gh pr merge 123 --squash` lacked `--match-head-commit`.
- A stale-verdict mutant removed the `--expect-head` comparison and was observed red because a moved head reached the provider merge call.
- `bash packages/mosaic/framework/tools/git/test-pr-merge-queue-branch.sh` initially returned rc 1; captured call was `--purpose merge -B main -t 900 -i 15`.

Logs remain untracked under the worktree as `.mosaic-test-work-red-*.log` and will not be committed.

## Progress

- [x] Mission, remediation charter, task evidence, board, issue #1019, and superseded PR #1023 read.
- [x] Isolated worktree created and identity configured coherently.
- [ ] Mutant tests authored and observed red.
- [ ] Implementation green.
- [ ] Baseline and situational gates green.
- [ ] Independent review clean.
- [ ] PR CI terminal-green at exact head by full step scan.
- [ ] Merge-gate verdict issued against frozen head.

## Risks / boundaries

- The local JSONL audit is durable operational evidence but not tamper-resistant against the same UID. RM-03 does not claim otherwise.
- Push-side audited exit 0 is an explicit owner ruling (Option B), accepted to avoid bricking recovery work; merge-side CANNOT_ASSERT remains retryable exit 75/HOLD. The automated security reviewer continues to flag the deliberate push availability tradeoff.
- Source/deployed-copy equality is owned by RM-02/D-22; this branch changes repository source and its tests only.

## Test evidence

Pending.

## Final evidence

Pending.