fix(rm-03): make CI queue guard fail on asserted non-readiness (#1032)

Co-authored-by: coder-mos1 <[email protected]>

docs/scratchpads/rm-03-queue-guard.md

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+# 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+- Do not cite the existing guard's green as evidence; D-23 establishes it is zero-information.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.
+- [x] Mutant tests authored and observed red.
+- [x] Implementation green.
+- [x] Baseline and focused situational gates green; full package suite has an unrelated framework-shell environment abort recorded below.
+- [ ] Independent review clean (rev-974 requested changes at `44ffa99a`; bypass remediation committed and awaiting re-review).
+- [ ] PR CI terminal-green at exact head by full step scan.
+- [ ] Merge-gate verdict issued against frozen head.
+
+## Scope disposition
+
+- The five framework guides are consequential documentation: they define the purpose-aware tri-state contract, including audited push degradation and merge HOLD.
+- The agent templates are consequential because they ship the same queue-guard instructions into newly seeded agent contracts; leaving them binary/stale would contradict the repaired tool.
+- `pr-merge.sh` is consequential: it must inspect the PR's exact head branch/repository/SHA and enforce the exact-head merge pin.
+- `pr-metadata.sh` is consequential only as the normalized source of that head branch/repository/SHA. Its diff is limited to exposing those fields on GitHub and Gitea.
+- `test-pr-merge-gitea-empty-uid.sh` changes because exact-head Gitea merges now always use the API path (the only path that can send `head_commit_id`), superseding the prior tea-empty-identity fallback behavior.
+
+## Review remediation
+
+- rev-974 independently proved that the documented `--skip-queue-guard` merge option bypassed an exit-99 guard stub, reached the provider merge payload, printed success, and exited 0 at head `44ffa99a`.
+- RED-first reproduction was added to `test-pr-merge-head-pin.sh` before the production fix: `FAIL merge-bypass: --skip-queue-guard reached the provider merge path`, suite rc 1. The test-only commit is `241113e6`.
+- Production remediation `37aae650` removes the option from parsing, usage, help, and examples. Every merge-capable path now invokes the queue guard; `--dry-run` alone omits it and has a regression proving that it exits before provider dispatch and creates no merge payload.
+- Existing Gitea merge tests now exercise a successful guard response rather than bypassing the guard.
+
+## 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
+
+Fresh after rescue checkpoint `b7175012`:
+
+- Focused situational matrix: tri-state, GitHub checks pagination, branch-absent, merge head branch/repository/SHA, exact-head pin, and Gitea exact-head API regressions all passed.
+- `bash -n` on the three production shell scripts passed.
+- `shellcheck -x -P packages/mosaic/framework/tools/git ...` on all changed shell scripts passed.
+- `pnpm typecheck` passed (45/45 Turbo tasks).
+- `pnpm lint` passed (25/25 Turbo tasks).
+- `pnpm format:check` passed.
+- `pnpm --filter @mosaicstack/mosaic test`: Vitest passed 1508/1508 on the confirmation run; framework-shell then aborted at the pre-existing wake coordinate assertion with exit 97: `BASH_LINENO ... probe reported [3 5], expected [3 4] ... (#973)`. This is outside the RM-03 diff and is disclosed rather than substituted or called green.
+- The prior package-suite attempt had one transient, out-of-diff `install-ordering-guard.spec.ts` failure (1/1508); its isolated rerun passed 19/19 and the confirmation full Vitest run passed 1508/1508.
+- After bypass remediation: all six focused RM-03 queue/merge regressions passed, including bypass refusal and dry-run non-dispatch; shell syntax and source-aware ShellCheck passed; `pnpm typecheck`, `pnpm lint`, and `pnpm format:check` passed.
+- Fresh `test:framework-shell` reached and passed every RM-03 test, then again aborted at the unrelated wake coordinate assertion with exit 97; it remains explicitly non-green rather than substituted.
+- An ad hoc raw Prettier invocation over `.template` and `.sh` files was unrunnable because no parser is registered for those extensions; it was not used as a substitute for canonical `pnpm format:check`.
+
+## Final evidence
+
+Pending.