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

Co-authored-by: coder-mos1 <[email protected]>
2026-08-01 18:55:26 +00:00
28 changed files with 1074 additions and 219 deletions
@@ -0,0 +1,120 @@
+# 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+- Do not cite the existing guard's green as evidence; D-23 establishes it is zero-information.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.
@@ -925,14 +925,16 @@ Woodpecker note:
 Before pushing a branch or merging a PR, guard against overlapping project pipelines:

 ```bash
-~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B main
-~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main
+~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push
+~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>
 ```

 Behavior:

- If pipeline state is running/queued/pending, wait until queue clears.
- If timeout or API/auth failure occurs, treat as `blocked`, report exact failed wrapper command, and stop.
+- If pipeline state is running/queued/pending, wait until queue clears; timeout is `ASSERTED_NOT_READY` and exits nonzero.
+- Failure, missing status, malformed status, or any other provider-asserted non-green state is `ASSERTED_NOT_READY` and exits nonzero.
+- Credential, transport, or provider unavailability is `CANNOT_ASSERT`: the guard emits a loud diagnostic and durable JSONL audit record. For push it exits 0 so recovery work is not bricked. For merge it returns distinct retryable exit 75 and holds until provider recovery; rerunning then self-clears without manual reset. This result is never evidence that CI was clear. If the audit cannot be written, the guard exits nonzero.
+- `pr-merge.sh` resolves and guards the exact PR head repository and full SHA automatically, including fork PRs.

 ## Gitea as Unified Platform

@@ -13,7 +13,7 @@ Merge strategy enforcement (HARD RULE):
 - PR target for delivery is `main`.
 - Direct pushes to `main` are prohibited.
 - Merge to `main` MUST be squash-only.
- Use `~/.config/mosaic/tools/git/pr-merge.sh -n {PR_NUMBER} -m squash` (or PowerShell equivalent).
+- Use `~/.config/mosaic/tools/git/pr-merge.sh -n {PR_NUMBER} -m squash --expect-head {approved_full_sha}` (or PowerShell equivalent).

 ## Review Checklist

@@ -79,7 +79,7 @@ For implementation work, you MUST run this cycle in order:
 8. `pre-push queue guard` - before pushing, wait for running/queued project pipelines to clear: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push`.
 9. `push` - push immediately after queue guard passes.
 10. `PR integration` - if external git provider is available, create/update PR to `main` and merge with required strategy via Mosaic wrappers.
-11. `pre-merge queue guard` - before merging PR, wait for running/queued project pipelines to clear: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge`.
+11. `pre-merge queue guard` - before merging PR, wait for running/queued project pipelines on the exact PR head to clear: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`.
 12. `CI/pipeline verification` - wait for terminal CI status and require green before completion (`~/.config/mosaic/tools/git/pr-ci-wait.sh` for PR-based workflow).
 13. `issue closure` - close linked external issue (or close internal `docs/TASKS.md` task ref when provider is unavailable).
 14. `greenfield situational test` - validate required user flows in a clean environment/startup path (post-merge for trunk workflow changes).
@@ -93,8 +93,8 @@ For implementation work, you MUST run this cycle in order:
 > the gate (AGENTS.md hard gate "Merge authority"). Solo delivery proceeds
 > without asking.

-1. `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main`
-2. `~/.config/mosaic/tools/git/pr-merge.sh -n <PR_NUMBER> -m squash`
+1. `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`
+2. `~/.config/mosaic/tools/git/pr-merge.sh -n <PR_NUMBER> -m squash --expect-head <APPROVED_FULL_SHA>`
 3. `~/.config/mosaic/tools/git/pr-ci-wait.sh -n <PR_NUMBER>`
 4. `~/.config/mosaic/tools/git/issue-close.sh -i <ISSUE_NUMBER>` (or close internal `docs/TASKS.md` ref when no provider exists)
 5. If any step fails: set status `blocked`, report the exact failed wrapper command, and stop.
@@ -425,11 +425,11 @@ git push
    and checklist completed (`~/.config/mosaic/templates/docs/DOCUMENTATION-CHECKLIST.md`) when applicable.
 13. **PR + CI + Issue Closure Gate** (HARD RULE for source-code tasks):
    - Before merging, run queue guard:
-      `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main`
+      `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`
    - Ensure PR exists for the task branch (create/update via wrappers if needed):
      `~/.config/mosaic/tools/git/pr-create.sh ... -B main`
    - Merge via wrapper:
-      `~/.config/mosaic/tools/git/pr-merge.sh -n {PR_NUMBER} -m squash`
+      `~/.config/mosaic/tools/git/pr-merge.sh -n {PR_NUMBER} -m squash --expect-head {approved_full_sha}`
    - Wait for terminal CI status:
      `~/.config/mosaic/tools/git/pr-ci-wait.sh -n {PR_NUMBER}`
    - Close linked issue after merge + green CI:
@@ -630,7 +630,7 @@ Construct this from the task row and pass to worker via Task tool:

 **MANDATORY:** This ALWAYS includes linting. If the project has a linter configured
 (ESLint, Biome, ruff, etc.), you MUST run it and fix ALL violations in files you touched.
-Do NOT leave lint warnings or errors for someone else to clean up. 6. Run REQUIRED situational tests based on changed surfaces (see `~/.config/mosaic/guides/E2E-DELIVERY.md` and `~/.config/mosaic/guides/QA-TESTING.md`). 7. If task is bug fix/security/auth/critical business logic, apply REQUIRED TDD discipline per `~/.config/mosaic/guides/QA-TESTING.md`. 8. If gates or required situational tests fail: Fix and retry. Do NOT report success with failures. 9. Commit: `git commit -m "fix({finding_id}): brief description"` 10. Before push, run queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B main` 11. Push: `git push origin {branch}` 12. Report result as JSON (see format below)
+Do NOT leave lint warnings or errors for someone else to clean up. 6. Run REQUIRED situational tests based on changed surfaces (see `~/.config/mosaic/guides/E2E-DELIVERY.md` and `~/.config/mosaic/guides/QA-TESTING.md`). 7. If task is bug fix/security/auth/critical business logic, apply REQUIRED TDD discipline per `~/.config/mosaic/guides/QA-TESTING.md`. 8. If gates or required situational tests fail: Fix and retry. Do NOT report success with failures. 9. Commit: `git commit -m "fix({finding_id}): brief description"` 10. Before push, run queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B {branch}` 11. Push: `git push origin {branch}` 12. Report result as JSON (see format below)

 ## Git Scripts

@@ -638,8 +638,9 @@ For issue/PR/milestone operations, use scripts (NOT raw tea/gh):

 - `~/.config/mosaic/tools/git/issue-view.sh -i {N}`
 - `~/.config/mosaic/tools/git/pr-create.sh -t "Title" -b "Desc" -B main`
- `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`
- `~/.config/mosaic/tools/git/pr-merge.sh -n {PR_NUMBER} -m squash`
+- Push: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B {task_branch}`
+- Merge: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B {pr_head_branch} -R {pr_head_owner/repo} --sha {pr_head_full_sha}`
+- `~/.config/mosaic/tools/git/pr-merge.sh -n {PR_NUMBER} -m squash --expect-head {approved_full_sha}`
 - `~/.config/mosaic/tools/git/pr-ci-wait.sh -n {PR_NUMBER}`
 - `~/.config/mosaic/tools/git/issue-close.sh -i {N}`

@@ -23,10 +23,12 @@ Mosaic wrappers at `~/.config/mosaic/tools/git/*.sh` handle platform detection a
 # Milestones
 ~/.config/mosaic/tools/git/milestone-create.sh

-# CI queue guard (required before push/merge)
+# CI queue guard (required before push/merge; defaults to the checked-out branch)
 ~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge
 ```

+The guard exits nonzero for any provider-asserted non-green, missing, or malformed CI state. If credentials or the provider are unavailable, it emits `CANNOT_ASSERT` and writes a JSONL audit record. Push degrades to exit 0 so recovery work is not bricked; merge holds with retryable exit 75 until the provider recovers, then self-clears without manual reset. Neither outcome is evidence that CI was clear. `pr-merge.sh` automatically inspects the exact PR head repository and full commit SHA rather than its `main` base; this also handles fork PRs without branch-name ambiguity. Pass `--expect-head <approved-full-sha>` to bind a commit-specific review or merge-gate verdict; Gitea uses atomic `head_commit_id` and GitHub uses `--match-head-commit`.
+
 ### Code Review (Codex)

 ```bash
@@ -9,7 +9,7 @@
 2. Do NOT ask for routine confirmation before required push/merge/issue-close/release/tag actions.
 3. Completion is forbidden at PR-open stage.
 4. Completion requires merged PR to `main` + terminal green CI + linked issue/internal task closed.
-5. Before push or merge, run queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+5. Before push or merge, run the queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.
 6. For issue/PR/milestone operations, use Mosaic wrappers first (`~/.config/mosaic/tools/git/*.sh`).
 7. If any required wrapper command fails: report `blocked` with the exact failed wrapper command and stop.
 8. Do NOT stop at "PR created" and do NOT ask "should I merge?" for routine flow.
@@ -88,7 +88,7 @@ Reference:
 5. Do not mark implementation complete until PR is merged.
 6. Do not mark implementation complete until CI/pipeline status is terminal green.
 7. Close linked issues/tasks only after merge + green CI.
-8. Before push or merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+8. Before push or merge, run the CI queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.

 ## Container Release Strategy (When Applicable)

@@ -147,9 +147,9 @@ Do NOT stop at "PR created" and do NOT ask "should I merge?" or "should I close
 5. Ensure `docs/PRD.md` or `docs/PRD.json` exists and is current before coding.
 6. Create scratchpad: `docs/scratchpads/{task-id}-{short-name}.md` and include issue/internal ref.
 7. Update `docs/TASKS.md` status + issue/internal ref before coding.
-8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B main`.
+8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push`.
 9. Open PR to `main` for delivery changes (no direct push to `main`).
-10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main`.
+10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`.
 11. Merge PRs that pass required checks and review gates with squash strategy only.
 12. Reference issues/internal refs in commits (`Fixes #123`, `Refs #123`, or `Refs TASKS:T1`).
 13. Close issue/internal task only after testing and documentation gates pass, PR merge is complete, and CI/pipeline status is terminal green.
@@ -9,7 +9,7 @@
 2. Do NOT ask for routine confirmation before required push/merge/issue-close/release/tag actions.
 3. Completion is forbidden at PR-open stage.
 4. Completion requires merged PR to `main` + terminal green CI + linked issue/internal task closed.
-5. Before push or merge, run queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+5. Before push or merge, run the queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.
 6. For issue/PR/milestone operations, use Mosaic wrappers first (`~/.config/mosaic/tools/git/*.sh`).
 7. If any required wrapper command fails: report `blocked` with the exact failed wrapper command and stop.
 8. Do NOT stop at "PR created" and do NOT ask "should I merge?" for routine flow.
@@ -97,7 +97,7 @@ Reference:
 5. Do not mark implementation complete until PR is merged.
 6. Do not mark implementation complete until CI/pipeline status is terminal green.
 7. Close linked issues/tasks only after merge + green CI.
-8. Before push or merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+8. Before push or merge, run the CI queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.


 ## Container Release Strategy (When Applicable)
@@ -198,9 +198,9 @@ Do NOT stop at "PR created" and do NOT ask "should I merge?" or "should I close
 5. Ensure `docs/PRD.md` or `docs/PRD.json` exists and is current before coding.
 6. Create scratchpad: `docs/scratchpads/{task-id}-{short-name}.md` and include issue/internal ref.
 7. Update `docs/TASKS.md` status + issue/internal ref before coding.
-8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B main`.
+8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push`.
 9. Open PR to `main` for delivery changes (no direct push to `main`).
-10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main`.
+10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`.
 11. Merge PRs that pass required checks and review gates with squash strategy only.
 12. Reference issues/internal refs in commits (`Fixes #123`, `Refs #123`, or `Refs TASKS:T1`).
 13. Close issue/internal task only after testing and documentation gates pass, PR merge is complete, and CI/pipeline status is terminal green.
@@ -9,7 +9,7 @@
 2. Do NOT ask for routine confirmation before required push/merge/issue-close/release/tag actions.
 3. Completion is forbidden at PR-open stage.
 4. Completion requires merged PR to `main` + terminal green CI + linked issue/internal task closed.
-5. Before push or merge, run queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+5. Before push or merge, run the queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.
 6. For issue/PR/milestone operations, use Mosaic wrappers first (`~/.config/mosaic/tools/git/*.sh`).
 7. If any required wrapper command fails: report `blocked` with the exact failed wrapper command and stop.
 8. Do NOT stop at "PR created" and do NOT ask "should I merge?" for routine flow.
@@ -101,7 +101,7 @@ Reference:
 5. Do not mark implementation complete until PR is merged.
 6. Do not mark implementation complete until CI/pipeline status is terminal green.
 7. Close linked issues/tasks only after merge + green CI.
-8. Before push or merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+8. Before push or merge, run the CI queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.


 ## Container Release Strategy (When Applicable)
@@ -230,9 +230,9 @@ Do NOT stop at "PR created" and do NOT ask "should I merge?" or "should I close
 5. Ensure `docs/PRD.md` or `docs/PRD.json` exists and is current before coding.
 6. Create scratchpad: `docs/scratchpads/{task-id}-{short-name}.md` and include issue/internal ref.
 7. Update `docs/TASKS.md` status + issue/internal ref before coding.
-8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B main`.
+8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push`.
 9. Open PR to `main` for delivery changes (no direct push to `main`).
-10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main`.
+10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`.
 11. Merge PRs that pass required checks and review gates with squash strategy only.
 12. Reference issues/internal refs in commits (`Fixes #123`, `Refs #123`, or `Refs TASKS:T1`).
 13. Close issue/internal task only after testing and documentation gates pass, PR merge is complete, and CI/pipeline status is terminal green.
@@ -9,7 +9,7 @@
 2. Do NOT ask for routine confirmation before required push/merge/issue-close/release/tag actions.
 3. Completion is forbidden at PR-open stage.
 4. Completion requires merged PR to `main` + terminal green CI + linked issue/internal task closed.
-5. Before push or merge, run queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+5. Before push or merge, run the queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.
 6. For issue/PR/milestone operations, use Mosaic wrappers first (`~/.config/mosaic/tools/git/*.sh`).
 7. If any required wrapper command fails: report `blocked` with the exact failed wrapper command and stop.
 8. Do NOT stop at "PR created" and do NOT ask "should I merge?" for routine flow.
@@ -87,7 +87,7 @@ Reference:
 5. Do not mark implementation complete until PR is merged.
 6. Do not mark implementation complete until CI/pipeline status is terminal green.
 7. Close linked issues/tasks only after merge + green CI.
-8. Before push or merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+8. Before push or merge, run the CI queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.

 ## Container Release Strategy (When Applicable)

@@ -146,9 +146,9 @@ Do NOT stop at "PR created" and do NOT ask "should I merge?" or "should I close
 5. Ensure `docs/PRD.md` or `docs/PRD.json` exists and is current before coding.
 6. Create scratchpad: `docs/scratchpads/{task-id}-{short-name}.md` and include issue/internal ref.
 7. Update `docs/TASKS.md` status + issue/internal ref before coding.
-8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B main`.
+8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push`.
 9. Open PR to `main` for delivery changes (no direct push to `main`).
-10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main`.
+10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`.
 11. Merge PRs that pass required checks and review gates with squash strategy only.
 12. Reference issues/internal refs in commits (`Fixes #123`, `Refs #123`, or `Refs TASKS:T1`).
 13. Close issue/internal task only after testing and documentation gates pass, PR merge is complete, and CI/pipeline status is terminal green.
@@ -9,7 +9,7 @@
 2. Do NOT ask for routine confirmation before required push/merge/issue-close/release/tag actions.
 3. Completion is forbidden at PR-open stage.
 4. Completion requires merged PR to `main` + terminal green CI + linked issue/internal task closed.
-5. Before push or merge, run queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+5. Before push or merge, run the queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.
 6. For issue/PR/milestone operations, use Mosaic wrappers first (`~/.config/mosaic/tools/git/*.sh`).
 7. If any required wrapper command fails: report `blocked` with the exact failed wrapper command and stop.
 8. Do NOT stop at "PR created" and do NOT ask "should I merge?" for routine flow.
@@ -84,7 +84,7 @@ Reference:
 5. Do not mark implementation complete until PR is merged.
 6. Do not mark implementation complete until CI/pipeline status is terminal green.
 7. Close linked issues/tasks only after merge + green CI.
-8. Before push or merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+8. Before push or merge, run the CI queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.

 ## Container Release Strategy (When Applicable)

@@ -136,9 +136,9 @@ Do NOT stop at "PR created" and do NOT ask "should I merge?" or "should I close
 5. Ensure `docs/PRD.md` or `docs/PRD.json` exists and is current before coding.
 6. Create scratchpad: `docs/scratchpads/{task-id}-{short-name}.md` and include issue/internal ref.
 7. Update `docs/TASKS.md` status + issue/internal ref before coding.
-8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B main`.
+8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push`.
 9. Open PR to `main` for delivery changes (no direct push to `main`).
-10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main`.
+10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`.
 11. Merge PRs that pass required checks and review gates with squash strategy only.
 12. Reference issues/internal refs in commits (`Fixes #123`, `Refs #123`, or `Refs TASKS:T1`).
 13. Close issue/internal task only after testing and documentation gates pass, PR merge is complete, and CI/pipeline status is terminal green.
@@ -9,7 +9,7 @@
 2. Do NOT ask for routine confirmation before required push/merge/issue-close/release/tag actions.
 3. Completion is forbidden at PR-open stage.
 4. Completion requires merged PR to `main` + terminal green CI + linked issue/internal task closed.
-5. Before push or merge, run queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+5. Before push or merge, run the queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.
 6. For issue/PR/milestone operations, use Mosaic wrappers first (`~/.config/mosaic/tools/git/*.sh`).
 7. If any required wrapper command fails: report `blocked` with the exact failed wrapper command and stop.
 8. Do NOT stop at "PR created" and do NOT ask "should I merge?" for routine flow.
@@ -85,7 +85,7 @@ Reference:
 5. Do not mark implementation complete until PR is merged.
 6. Do not mark implementation complete until CI/pipeline status is terminal green.
 7. Close linked issues/tasks only after merge + green CI.
-8. Before push or merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push|merge -B main`.
+8. Before push or merge, run the CI queue guard against the push branch or the merge PR's exact head repository/SHA (`ci-queue-wait.sh --help`); `pr-merge.sh` supplies exact merge metadata automatically.

 ## Container Release Strategy (When Applicable)

@@ -133,9 +133,9 @@ Do NOT stop at "PR created" and do NOT ask "should I merge?" or "should I close
 5. Ensure `docs/PRD.md` or `docs/PRD.json` exists and is current before coding.
 6. Create scratchpad: `docs/scratchpads/{task-id}-{short-name}.md` and include issue/internal ref.
 7. Update `docs/TASKS.md` status + issue/internal ref before coding.
-8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B main`.
+8. Before push, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push`.
 9. Open PR to `main` for delivery changes (no direct push to `main`).
-10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B main`.
+10. Before merge, run CI queue guard: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`.
 11. Merge PRs that pass required checks and review gates with squash strategy only.
 12. Reference issues/internal refs in commits (`Fixes #123`, `Refs #123`, or `Refs TASKS:T1`).
 13. Close issue/internal task only after testing and documentation gates pass, PR merge is complete, and CI/pipeline status is terminal green.
@@ -7,7 +7,9 @@ set -euo pipefail
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/detect-platform.sh"

-BRANCH="main"
+BRANCH=""
+TARGET_REPO=""
+HEAD_SHA=""
 TIMEOUT_SEC=900
 INTERVAL_SEC=15
 PURPOSE="merge"
@@ -15,10 +17,12 @@ REQUIRE_STATUS=0

 usage() {
    cat <<EOF
-Usage: $(basename "$0") [-B branch] [-t timeout_sec] [-i interval_sec] [--purpose push|merge] [--require-status]
+Usage: $(basename "$0") [-B branch] [-R owner/repo] [--sha full-40] [-t timeout_sec] [-i interval_sec] [--purpose push|merge] [--require-status]

 Options:
-  -B, --branch BRANCH      Branch head to inspect (default: main)
+  -B, --branch BRANCH      Branch head to inspect (default: current branch)
+  -R, --repo OWNER/REPO    Repository containing the branch (default: origin repo)
+      --sha FULL_SHA       Inspect this exact 40-character commit instead of resolving the branch
  -t, --timeout SECONDS    Max wait time in seconds (default: 900)
  -i, --interval SECONDS   Poll interval in seconds (default: 15)
      --purpose VALUE      Log context: push|merge (default: merge)
@@ -27,63 +31,65 @@ Options:

 Examples:
  $(basename "$0")
-  $(basename "$0") --purpose push -B main -t 600 -i 10
+  $(basename "$0") --purpose push -t 600 -i 10
 EOF
 }

 # get_remote_host and get_gitea_token are provided by detect-platform.sh

 get_state_from_status_json() {
-    python3 - <<'PY'
+    # Python source comes from -c so the provider payload remains on stdin.
+    # Never move the payload to argv: commit-status responses can exceed ARG_MAX.
+    python3 -c '
 import json
 import sys

 try:
    payload = json.load(sys.stdin)
+    if not isinstance(payload, dict):
+        raise ValueError("status payload is not an object")
 except Exception:
-    print("unknown")
+    print("malformed")
    raise SystemExit(0)

-statuses = payload.get("statuses") or []
-state = (payload.get("state") or "").lower()
+raw_statuses = payload.get("statuses", [])
+raw_state = payload.get("state", "")
+if not isinstance(raw_statuses, list) or not isinstance(raw_state, str):
+    print("malformed")
+    raise SystemExit(0)
+statuses = raw_statuses
+state = raw_state.lower()

 pending_values = {"pending", "queued", "running", "waiting"}
 failure_values = {"failure", "error", "failed"}
 success_values = {"success"}

-if state in pending_values:
-    print("pending")
-    raise SystemExit(0)
-if state in failure_values:
-    print("terminal-failure")
-    raise SystemExit(0)
-if state in success_values:
-    print("terminal-success")
-    raise SystemExit(0)
-
 values = []
 for item in statuses:
    if not isinstance(item, dict):
-        continue
-    value = (item.get("status") or item.get("state") or "").lower()
-    if value:
-        values.append(value)
+        print("malformed")
+        raise SystemExit(0)
+    raw_value = item.get("status") or item.get("state")
+    if not isinstance(raw_value, str) or not raw_value:
+        print("malformed")
+        raise SystemExit(0)
+    values.append(raw_value.lower())

-if not values and not state:
-    print("no-status")
-elif any(v in pending_values for v in values):
+if any(value in pending_values for value in values) or state in pending_values:
    print("pending")
-elif any(v in failure_values for v in values):
+elif any(value in failure_values for value in values) or state in failure_values:
    print("terminal-failure")
-elif values and all(v in success_values for v in values):
+elif values and all(value in success_values for value in values) and state in {"", "success"}:
    print("terminal-success")
+elif not values:
+    print("no-status")
 else:
    print("unknown")
-PY
+'
 }

 print_pending_contexts() {
-    python3 - <<'PY'
+    python3 -c '
 import json
 import sys

@@ -104,17 +110,61 @@ for item in statuses:
    if not isinstance(item, dict):
        continue
    name = item.get("context") or item.get("name") or "unknown-context"
-    value = (item.get("status") or item.get("state") or "unknown").lower()
+    value = str(item.get("status") or item.get("state") or "unknown").lower()
    target = item.get("target_url") or item.get("url") or ""
    if value in pending_values:
        found = True
-        if target:
-            print(f"[ci-queue-wait] pending: {name}={value} ({target})")
-        else:
-            print(f"[ci-queue-wait] pending: {name}={value}")
+        suffix = f" ({target})" if target else ""
+        print(f"[ci-queue-wait] pending: {name}={value}{suffix}")
 if not found:
    print("[ci-queue-wait] no pending contexts")
+'
+}
+
+record_cannot_assert() {
+    local reason="$1"
+    local audit_log="${MOSAIC_CI_QUEUE_AUDIT_LOG:-${XDG_STATE_HOME:-${HOME:-}/.local/state}/mosaic/audit/ci-queue-wait.jsonl}"
+
+    if [[ -z "$audit_log" ]] || ! mkdir -p "$(dirname "$audit_log")"; then
+        echo "Error: CANNOT_ASSERT and audit directory is unavailable; refusing degraded pass." >&2
+        return 70
+    fi
+
+    if ! python3 - "$audit_log" "$reason" "${PLATFORM:-unknown}" "$PURPOSE" "${BRANCH:-unknown}" "${OWNER:-unknown}/${REPO:-unknown}" <<'PY'
+import datetime
+import json
+import os
+import sys
+
+path, reason, platform, purpose, branch, repo = sys.argv[1:]
+record = {
+    "timestamp": datetime.datetime.now(datetime.timezone.utc).isoformat(),
+    "outcome": "CANNOT_ASSERT",
+    "reason": reason,
+    "platform": platform,
+    "purpose": purpose,
+    "disposition": "hold" if purpose == "merge" else "degraded-pass",
+    "branch": branch,
+    "repo": repo,
+}
+fd = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_APPEND, 0o600)
+try:
+    os.write(fd, (json.dumps(record, separators=(",", ":")) + "\n").encode())
+finally:
+    os.close(fd)
 PY
+    then
+        echo "Error: CANNOT_ASSERT and audit write failed at ${audit_log}; refusing degraded pass." >&2
+        return 70
+    fi
+
+    if [[ "$PURPOSE" == "merge" ]]; then
+        echo "[ci-queue-wait] CANNOT_ASSERT reason=${reason} purpose=merge branch=${BRANCH:-unknown}; audited=${audit_log}; HOLD (exit 75). Retry after provider recovery; no manual reset is required." >&2
+        return 75
+    fi
+
+    echo "[ci-queue-wait] CANNOT_ASSERT reason=${reason} purpose=push branch=${BRANCH:-unknown}; audited=${audit_log}; push may proceed in degraded mode." >&2
+    return 0
 }

 github_get_branch_head_sha() {
@@ -128,7 +178,87 @@ github_get_commit_status_json() {
    local owner="$1"
    local repo="$2"
    local sha="$3"
-    gh api "repos/${owner}/${repo}/commits/${sha}/status"
+    local work_root status_file checks_file
+    work_root="${AGENT_WORK_ROOT:-${HOME:-}/.cache/mosaic/ci-queue-wait}"
+    mkdir -p "$work_root" || return 1
+    status_file=$(mktemp "$work_root/github-status.XXXXXX") || return 1
+    checks_file=$(mktemp "$work_root/github-checks.XXXXXX") || {
+        rm -f "$status_file"
+        return 1
+    }
+
+    if ! gh api --paginate --slurp "repos/${owner}/${repo}/commits/${sha}/statuses?per_page=100" > "$status_file" ||
+       ! gh api --paginate --slurp "repos/${owner}/${repo}/commits/${sha}/check-runs?per_page=100&filter=latest" > "$checks_file"; then
+        rm -f "$status_file" "$checks_file"
+        return 1
+    fi
+
+    python3 - "$status_file" "$checks_file" <<'PY'
+import json
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    status_pages = json.load(handle)
+with open(sys.argv[2], encoding="utf-8") as handle:
+    check_pages = json.load(handle)
+
+if not isinstance(status_pages, list) or not isinstance(check_pages, list):
+    raise SystemExit(1)
+
+# The statuses endpoint is newest-first and can contain retries for one context.
+# Keep only the newest entry per context after flattening every page.
+combined = []
+seen_contexts = set()
+for page in status_pages:
+    if not isinstance(page, list):
+        raise SystemExit(1)
+    for status in page:
+        if not isinstance(status, dict):
+            raise SystemExit(1)
+        context = status.get("context")
+        if not isinstance(context, str) or not context or context in seen_contexts:
+            continue
+        seen_contexts.add(context)
+        combined.append(status)
+
+check_runs = []
+reported_total = 0
+for page in check_pages:
+    if not isinstance(page, dict):
+        raise SystemExit(1)
+    page_runs = page.get("check_runs") or []
+    total_count = page.get("total_count")
+    if not isinstance(page_runs, list) or not isinstance(total_count, int):
+        raise SystemExit(1)
+    reported_total = max(reported_total, total_count)
+    check_runs.extend(page_runs)
+if len(check_runs) < reported_total:
+    raise SystemExit(1)
+
+for run in check_runs:
+    if not isinstance(run, dict):
+        raise SystemExit(1)
+    status = run.get("status")
+    conclusion = run.get("conclusion")
+    if status != "completed":
+        value = "pending"
+    elif conclusion == "success":
+        value = "success"
+    elif conclusion in {"failure", "cancelled", "timed_out", "action_required", "startup_failure", "stale"}:
+        value = "failure"
+    else:
+        value = "unknown"
+    combined.append({
+        "context": run.get("name") or "github-check",
+        "status": value,
+        "target_url": run.get("html_url") or run.get("details_url") or "",
+    })
+
+json.dump({"state": "", "statuses": combined}, sys.stdout)
+PY
+    local status=$?
+    rm -f "$status_file" "$checks_file"
+    return "$status"
 }

 gitea_get_branch_head_sha() {
@@ -174,6 +304,14 @@ while [[ $# -gt 0 ]]; do
            BRANCH="$2"
            shift 2
            ;;
+        -R|--repo)
+            TARGET_REPO="$2"
+            shift 2
+            ;;
+        --sha)
+            HEAD_SHA="$2"
+            shift 2
+            ;;
        -t|--timeout)
            TIMEOUT_SEC="$2"
            shift 2
@@ -206,45 +344,89 @@ if ! [[ "$TIMEOUT_SEC" =~ ^[0-9]+$ ]] || ! [[ "$INTERVAL_SEC" =~ ^[0-9]+$ ]]; th
    echo "Error: timeout and interval must be integer seconds." >&2
    exit 1
 fi
+if [[ -n "$HEAD_SHA" && ! "$HEAD_SHA" =~ ^[0-9a-fA-F]{40}$ ]]; then
+    echo "Error: --sha must be a full 40-character hexadecimal commit SHA." >&2
+    exit 1
+fi
+if [[ -n "$TARGET_REPO" && ! "$TARGET_REPO" =~ ^[^/[:space:]]+/[^/[:space:]]+$ ]]; then
+    echo "Error: --repo must be OWNER/REPO." >&2
+    exit 1
+fi

-OWNER=$(get_repo_owner)
-REPO=$(get_repo_name)
-detect_platform > /dev/null
+if [[ "$PURPOSE" != "push" && "$PURPOSE" != "merge" ]]; then
+    echo "Error: --purpose must be push or merge." >&2
+    exit 1
+fi
+
+OWNER="unknown"
+REPO="unknown"
+PLATFORM="unknown"
+if ! OWNER=$(get_repo_owner) || [[ -z "$OWNER" ]]; then
+    record_cannot_assert "repository-owner-unresolvable"
+    exit $?
+fi
+if ! REPO=$(get_repo_name) || [[ -z "$REPO" ]]; then
+    record_cannot_assert "repository-name-unresolvable"
+    exit $?
+fi
+if ! detect_platform > /dev/null; then
+    PLATFORM="${PLATFORM:-unknown}"
+    record_cannot_assert "unsupported-platform"
+    exit $?
+fi
 PLATFORM="${PLATFORM:-unknown}"

+if [[ -n "$TARGET_REPO" ]]; then
+    OWNER="${TARGET_REPO%%/*}"
+    REPO="${TARGET_REPO##*/}"
+fi
+
+if [[ -z "$BRANCH" ]]; then
+    if ! BRANCH=$(git symbolic-ref --quiet --short HEAD) || [[ -z "$BRANCH" ]]; then
+        record_cannot_assert "current-branch-unresolvable"
+        exit $?
+    fi
+fi
+
 if [[ "$PLATFORM" == "github" ]]; then
    if ! command -v gh >/dev/null 2>&1; then
-        echo "Error: gh CLI is required for GitHub CI queue guard." >&2
-        exit 1
+        record_cannot_assert "github-cli-unavailable"
+        exit $?
    fi
-    HEAD_SHA=$(github_get_branch_head_sha "$OWNER" "$REPO" "$BRANCH")
    if [[ -z "$HEAD_SHA" ]]; then
-        echo "Error: Could not resolve ${BRANCH} head SHA." >&2
-        exit 1
+        if ! HEAD_SHA=$(github_get_branch_head_sha "$OWNER" "$REPO" "$BRANCH") || [[ -z "$HEAD_SHA" ]]; then
+            record_cannot_assert "branch-head-unavailable"
+            exit $?
+        fi
    fi
    echo "[ci-queue-wait] platform=github purpose=${PURPOSE} branch=${BRANCH} sha=${HEAD_SHA}"
 elif [[ "$PLATFORM" == "gitea" ]]; then
-    HOST=$(get_remote_host) || {
-        echo "Error: Could not determine remote host." >&2
-        exit 1
-    }
-    TOKEN=$(get_gitea_token "$HOST") || {
-        echo "Error: Gitea token not found. Set GITEA_TOKEN or configure ~/.git-credentials." >&2
-        exit 1
-    }
-    HEAD_SHA=$(gitea_get_branch_head_sha "$HOST" "$OWNER/$REPO" "$BRANCH" "$TOKEN")
-    if [[ "$HEAD_SHA" == "__BRANCH_ABSENT__" ]]; then
-        echo "[ci-queue-wait] branch ${BRANCH} not yet on remote — no in-flight pipeline; queue clear."
-        exit 0
+    if ! HOST=$(get_remote_host) || [[ -z "$HOST" ]]; then
+        record_cannot_assert "remote-host-unresolvable"
+        exit $?
+    fi
+    if ! TOKEN=$(get_gitea_token "$HOST") || [[ -z "$TOKEN" ]]; then
+        record_cannot_assert "credential-unresolvable"
+        exit $?
    fi
    if [[ -z "$HEAD_SHA" ]]; then
-        echo "Error: Could not resolve ${BRANCH} head SHA." >&2
-        exit 1
+        if ! HEAD_SHA=$(gitea_get_branch_head_sha "$HOST" "$OWNER/$REPO" "$BRANCH" "$TOKEN"); then
+            record_cannot_assert "branch-head-unavailable"
+            exit $?
+        fi
+        if [[ "$HEAD_SHA" == "__BRANCH_ABSENT__" ]]; then
+            echo "[ci-queue-wait] branch ${BRANCH} not yet on remote — no in-flight pipeline; queue clear."
+            exit 0
+        fi
+        if [[ -z "$HEAD_SHA" ]]; then
+            record_cannot_assert "branch-head-unavailable"
+            exit $?
+        fi
    fi
    echo "[ci-queue-wait] platform=gitea purpose=${PURPOSE} branch=${BRANCH} sha=${HEAD_SHA}"
 else
-    echo "Error: Unsupported platform '${PLATFORM}'." >&2
-    exit 1
+    record_cannot_assert "unsupported-platform"
+    exit $?
 fi

 START_TS=$(date +%s)
@@ -253,14 +435,20 @@ DEADLINE_TS=$((START_TS + TIMEOUT_SEC))
 while true; do
    NOW_TS=$(date +%s)
    if (( NOW_TS > DEADLINE_TS )); then
-        echo "Error: Timed out waiting for CI queue to clear on ${BRANCH} after ${TIMEOUT_SEC}s." >&2
+        echo "Error: ASSERTED_NOT_READY state=pending; timed out waiting for CI queue to clear on ${BRANCH} after ${TIMEOUT_SEC}s." >&2
        exit 124
    fi

    if [[ "$PLATFORM" == "github" ]]; then
-        STATUS_JSON=$(github_get_commit_status_json "$OWNER" "$REPO" "$HEAD_SHA")
+        if ! STATUS_JSON=$(github_get_commit_status_json "$OWNER" "$REPO" "$HEAD_SHA"); then
+            record_cannot_assert "status-provider-unreachable"
+            exit $?
+        fi
    else
-        STATUS_JSON=$(gitea_get_commit_status_json "$HOST" "$OWNER/$REPO" "$HEAD_SHA" "$TOKEN")
+        if ! STATUS_JSON=$(gitea_get_commit_status_json "$HOST" "$OWNER/$REPO" "$HEAD_SHA" "$TOKEN"); then
+            record_cannot_assert "status-provider-unreachable"
+            exit $?
+        fi
    fi

    STATE=$(printf '%s' "$STATUS_JSON" | get_state_from_status_json)
@@ -271,21 +459,24 @@ while true; do
            printf '%s' "$STATUS_JSON" | print_pending_contexts
            sleep "$INTERVAL_SEC"
            ;;
+        terminal-success)
+            exit 0
+            ;;
        no-status)
            if [[ "$REQUIRE_STATUS" -eq 1 ]]; then
-                echo "Error: No CI status contexts found for ${BRANCH} while --require-status is set." >&2
-                exit 1
+                echo "Error: ASSERTED_NOT_READY state=no-status; --require-status was set for ${BRANCH}." >&2
+            else
+                echo "Error: ASSERTED_NOT_READY state=no-status purpose=${PURPOSE} branch=${BRANCH}." >&2
            fi
-            echo "[ci-queue-wait] no status contexts present; proceeding."
-            exit 0
+            exit 3
            ;;
-        terminal-success|terminal-failure|unknown)
-            # Queue guard only blocks on pending/running/queued states.
-            exit 0
+        terminal-failure|malformed|unknown)
+            echo "Error: ASSERTED_NOT_READY state=${STATE} purpose=${PURPOSE} branch=${BRANCH}." >&2
+            exit 3
            ;;
        *)
-            echo "[ci-queue-wait] unrecognized state '${STATE}', proceeding conservatively."
-            exit 0
+            echo "Error: ASSERTED_NOT_READY unrecognized-state=${STATE} purpose=${PURPOSE} branch=${BRANCH}." >&2
+            exit 3
            ;;
    esac
 done
@@ -1,6 +1,6 @@
 #!/bin/bash
 # pr-merge.sh - Merge pull requests on Gitea or GitHub
-# Usage: pr-merge.sh -n PR_NUMBER [-m squash] [-d] [--skip-queue-guard]
+# Usage: pr-merge.sh -n PR_NUMBER [-m squash] [-d]

 set -euo pipefail

@@ -12,8 +12,8 @@ source "$SCRIPT_DIR/detect-platform.sh"
 PR_NUMBER=""
 MERGE_METHOD="squash"
 DELETE_BRANCH=false
-SKIP_QUEUE_GUARD=false
 DRY_RUN=false
+EXPECT_HEAD=""

 usage() {
    cat <<EOF
@@ -25,15 +25,14 @@ Options:
    -n, --number NUMBER     PR number to merge (required)
    -m, --method METHOD     Merge method: squash only (default: squash)
    -d, --delete-branch     Delete the head branch after merge
-        --skip-queue-guard  Skip CI queue guard wait before merge
        --dry-run           Run metadata/login preflight without merging
+        --expect-head SHA   Refuse unless the PR head matches this full commit SHA
    -h, --help              Show this help message

 Examples:
    $(basename "$0") -n 42                    # Merge PR #42
    $(basename "$0") -n 42 -m squash          # Squash merge
    $(basename "$0") -n 42 -d                 # Squash merge and delete branch
-    $(basename "$0") -n 42 --skip-queue-guard # Skip queue guard wait
 EOF
    exit "${1:-1}"
 }
@@ -53,15 +52,14 @@ while [[ $# -gt 0 ]]; do
            DELETE_BRANCH=true
            shift
            ;;
-        --skip-queue-guard)
-            SKIP_QUEUE_GUARD=true
-            shift
-            ;;
        --dry-run)
            DRY_RUN=true
-            SKIP_QUEUE_GUARD=true
            shift
            ;;
+        --expect-head)
+            EXPECT_HEAD="$2"
+            shift 2
+            ;;
        -h|--help)
            usage 0
            ;;
@@ -86,18 +84,36 @@ if [[ "$MERGE_METHOD" != "squash" ]]; then
    echo "Error: Mosaic policy enforces squash merge only. Received '$MERGE_METHOD'." >&2
    exit 1
 fi
+if [[ -n "$EXPECT_HEAD" && ! "$EXPECT_HEAD" =~ ^[0-9a-fA-F]{40}$ ]]; then
+    echo "Error: --expect-head must be a full 40-character hexadecimal commit SHA." >&2
+    exit 1
+fi

 PR_METADATA="$("$SCRIPT_DIR/pr-metadata.sh" -n "$PR_NUMBER")"
 BASE_BRANCH="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("baseRefName") or "").strip())')"
+HEAD_BRANCH="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("headRefName") or "").strip())')"
+HEAD_SHA="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("headRefOid") or "").strip())')"
+HEAD_REPO="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; value=json.load(sys.stdin).get("headRepository") or ""; print((value.get("nameWithOwner") or value.get("full_name") or "") if isinstance(value, dict) else str(value).strip())')"
 if [[ "$BASE_BRANCH" != "main" ]]; then
    echo "Error: Mosaic policy allows merges only for PRs targeting 'main' (found '$BASE_BRANCH')." >&2
    exit 1
 fi

-if [[ "$SKIP_QUEUE_GUARD" != true ]]; then
+if [[ -z "$HEAD_BRANCH" || -z "$HEAD_REPO" || ! "$HEAD_SHA" =~ ^[0-9a-fA-F]{40}$ ]]; then
+    echo "Error: Could not resolve the PR head branch, repository, and full commit SHA for queue inspection." >&2
+    exit 1
+fi
+if [[ -n "$EXPECT_HEAD" && "$HEAD_SHA" != "$EXPECT_HEAD" ]]; then
+    echo "Error: PR head moved: expected $EXPECT_HEAD, found $HEAD_SHA." >&2
+    exit 1
+fi
+
+if [[ "$DRY_RUN" != true ]]; then
    "$SCRIPT_DIR/ci-queue-wait.sh" \
        --purpose merge \
-        -B "$BASE_BRANCH" \
+        -B "$HEAD_BRANCH" \
+        -R "$HEAD_REPO" \
+        --sha "$HEAD_SHA" \
        -t "${MOSAIC_CI_QUEUE_TIMEOUT_SEC:-900}" \
        -i "${MOSAIC_CI_QUEUE_POLL_SEC:-15}"
 fi
@@ -106,31 +122,22 @@ PLATFORM=$(detect_platform)
 OWNER=$(get_repo_owner)
 REPO=$(get_repo_name)

-is_known_tea_empty_identity_failure() {
-    local error_file="$1"
-
-    python3 - "$error_file" <<'PY'
-import re
-import sys
-
-with open(sys.argv[1], encoding="utf-8", errors="replace") as handle:
-    error = handle.read()
-
-known_empty_identity = re.search(
-    r"user does not exist.*\[.*uid:\s*0,\s*name:\s*\]",
-    error,
-    flags=re.IGNORECASE | re.DOTALL,
-)
-raise SystemExit(0 if known_empty_identity else 1)
-PY
-}
-
 merge_gitea_with_api() {
    local host="$1" api_url token basic_auth body_file raw_code payload
    api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}/merge"
    mkdir -p "${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}"
    body_file=$(mktemp "${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}/pr-merge-api-response.XXXXXX")
-    payload='{"Do":"squash"}'
+    payload=$(python3 - "$HEAD_SHA" "$DELETE_BRANCH" <<'PY'
+import json
+import sys
+
+head_sha, delete_branch = sys.argv[1:]
+payload = {"Do": "squash", "head_commit_id": head_sha}
+if delete_branch == "true":
+    payload["delete_branch_after_merge"] = True
+print(json.dumps(payload, separators=(",", ":")))
+PY
+)

    token=$(get_gitea_token "$host" || true)
    if [[ -n "$token" ]]; then
@@ -202,7 +209,7 @@ fi

 case "$PLATFORM" in
    github)
-        cmd=(gh pr merge "$PR_NUMBER" --squash)
+        cmd=(gh pr merge "$PR_NUMBER" --squash --match-head-commit "$HEAD_SHA")
        [[ "$DELETE_BRANCH" == true ]] && cmd+=(--delete-branch)
        "${cmd[@]}"
        ;;
@@ -211,32 +218,9 @@ case "$PLATFORM" in
            echo "Error: Cannot determine host from origin remote URL" >&2
            exit 1
        }
-        TEA_LOGIN="$(get_gitea_login_for_host "$HOST" || true)"
-
-        if [[ -n "$TEA_LOGIN" ]]; then
-            mkdir -p "${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}"
-            TEA_ERROR_FILE=$(mktemp "${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}/pr-merge-tea-error.XXXXXX")
-            if tea pr merge "$PR_NUMBER" --style squash --repo "$OWNER/$REPO" --login "$TEA_LOGIN" 2> "$TEA_ERROR_FILE"; then
-                rm -f "$TEA_ERROR_FILE"
-            elif is_known_tea_empty_identity_failure "$TEA_ERROR_FILE"; then
-                cat "$TEA_ERROR_FILE" >&2
-                echo "Known tea empty identity failure detected; using authenticated Gitea API merge fallback." >&2
-                rm -f "$TEA_ERROR_FILE"
-                merge_gitea_with_api "$HOST"
-            else
-                cat "$TEA_ERROR_FILE" >&2
-                rm -f "$TEA_ERROR_FILE"
-                exit 1
-            fi
-        else
-            echo "No tea login configured for $HOST; using authenticated Gitea API merge fallback." >&2
-            merge_gitea_with_api "$HOST"
-        fi
-
-        # Delete branch after merge if requested
-        if [[ "$DELETE_BRANCH" == true ]]; then
-            echo "Note: Branch deletion after merge may need to be done separately with tea" >&2
-        fi
+        # Gitea's API head_commit_id is an atomic compare-and-merge precondition.
+        # tea cannot express it, so exact-head merges use the authenticated API path.
+        merge_gitea_with_api "$HOST"
        ;;
    *)
        echo "Error: Could not detect git platform" >&2
@@ -109,7 +109,7 @@ PY
 detect_platform > /dev/null

 if [[ "$PLATFORM" == "github" ]]; then
-    METADATA=$(gh pr view "$PR_NUMBER" --json number,title,body,state,author,headRefName,baseRefName,files,labels,assignees,milestone,createdAt,updatedAt,url,isDraft)
+    METADATA=$(gh pr view "$PR_NUMBER" --json number,title,body,state,author,headRefName,headRefOid,headRepository,baseRefName,files,labels,assignees,milestone,createdAt,updatedAt,url,isDraft)
    write_metadata "$METADATA"
 elif [[ "$PLATFORM" == "gitea" ]]; then
    OWNER=$(get_repo_owner)
@@ -182,6 +182,25 @@ if isinstance(head_ref, str) and head_ref.startswith('refs/pull/'):
        data.get('head_ref'),
        head_ref,
    )
+head_sha = first_non_empty(
+    nested(data, 'head', 'sha'),
+    nested(data, 'head', 'id'),
+    data.get('head_sha'),
+)
+head_repo = first_non_empty(
+    nested(data, 'head', 'repo', 'full_name'),
+    nested(data, 'head', 'repo', 'name_with_owner'),
+)
+if not head_repo:
+    head_repo_owner = first_non_empty(
+        nested(data, 'head', 'repo', 'owner', 'login'),
+        nested(data, 'head', 'repo', 'owner', 'username'),
+        nested(data, 'head', 'repo', 'owner_name'),
+    )
+    head_repo_name = first_non_empty(nested(data, 'head', 'repo', 'name'))
+    if head_repo_owner and head_repo_name:
+        head_repo = f'{head_repo_owner}/{head_repo_name}'
+
 base_ref = first_non_empty(
    nested(data, 'base', 'ref'),
    nested(data, 'base', 'name'),
@@ -207,6 +226,8 @@ normalized = {
    'state': data.get('state'),
    'author': nested(data, 'user', 'login') or '',
    'headRefName': head_ref,
+    'headRefOid': head_sha,
+    'headRepository': head_repo,
    'baseRefName': base_ref,
    'labels': [l.get('name', '') for l in data.get('labels', []) if isinstance(l, dict)],
    'assignees': [a.get('login', '') for a in data.get('assignees', []) if isinstance(a, dict)],
@@ -13,7 +13,7 @@
 # Covers:
 #   (a) 404 branch-absent          -> exit 0, "queue clear" message.
 #   (b) 200 existing branch + a terminal CI state -> unchanged behavior.
-#   (c) genuine API error (500)    -> still fail-closed (nonzero exit).
+#   (c) genuine API error (500)    -> loud, audited CANNOT_ASSERT; degraded exit 0.

 set -euo pipefail

@@ -62,7 +62,7 @@ case "$mode" in
    200)  code=200; body='{"commit":{"id":"deadbeefcafef00d0123456789abcdef01234567"}}' ;;
    500)  code=500; body='{"message":"internal server error"}' ;;
    no-status)         code=200; body='{}' ;;
-    terminal-success)  code=200; body='{"state":"success"}' ;;
+    terminal-success)  code=200; body='{"state":"success","statuses":[{"status":"success"}]}' ;;
    *)
        echo "curl stub: unknown mode=$mode" >&2
        exit 2
@@ -91,6 +91,7 @@ run_ci_queue_wait() {
        export MOSAIC_CREDENTIALS_FILE="$WORK_DIR/no-credentials.json"
        export GITEA_TOKEN="stub-token"
        export GITEA_URL="https://git.example.test"
+        export MOSAIC_CI_QUEUE_AUDIT_LOG="$WORK_DIR/audit/ci-queue-wait.jsonl"
        "$SCRIPT_DIR/ci-queue-wait.sh" -B "$branch" --purpose push -t 5 -i 1
    )
 }
@@ -131,19 +132,26 @@ elif [[ "$out_b" == *"queue clear"* ]]; then
    fail=1
 fi

-# (c) genuine API error (500) -> still fail-closed, exit nonzero.
+# (c) genuine API error (500) -> CANNOT_ASSERT is loud and audited, but does not brick delivery.
 set +e
 out_c=$(MOSAIC_STUB_BRANCH_MODE=500 run_ci_queue_wait "feat/some-branch" 2>&1)
 status_c=$?
 set -e
-if [[ "$status_c" -eq 0 ]]; then
-    echo "FAIL(c): expected a nonzero exit for a genuine 500 API error, got 0" >&2
+if [[ "$status_c" -ne 0 ]]; then
+    echo "FAIL(c): expected degraded exit 0 for provider unavailability, got $status_c" >&2
+    echo "$out_c" >&2
+    fail=1
+elif [[ "$out_c" != *"CANNOT_ASSERT"* ]]; then
+    echo "FAIL(c): expected a loud CANNOT_ASSERT diagnostic" >&2
    echo "$out_c" >&2
    fail=1
 elif [[ "$out_c" == *"queue clear"* ]]; then
    echo "FAIL(c): a genuine API error must not be reported as queue-clear" >&2
    echo "$out_c" >&2
    fail=1
+elif [[ ! -s "$WORK_DIR/audit/ci-queue-wait.jsonl" ]]; then
+    echo "FAIL(c): expected a durable CANNOT_ASSERT audit record" >&2
+    fail=1
 fi

 if [[ "$fail" -eq 0 ]]; then
@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+# GitHub Actions uses Checks API check-runs, not only legacy commit statuses.
+
+set -u
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/ci-queue-wait-github-checks}"
+REPO_DIR="$WORK_DIR/repo"
+STUB_DIR="$WORK_DIR/stubs"
+rm -rf "$WORK_DIR"
+mkdir -p "$REPO_DIR" "$STUB_DIR"
+git -C "$REPO_DIR" init -q
+git -C "$REPO_DIR" checkout -q -b fix/github-checks
+git -C "$REPO_DIR" remote add origin https://github.com/acme/widgets.git
+
+cat > "$STUB_DIR/gh" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+endpoint=""
+for arg in "$@"; do
+    [[ "$arg" == repos/* ]] && endpoint="$arg"
+done
+printf '%s\n' "$*" >> "${MOSAIC_GH_CALL_LOG:?}"
+case "$endpoint" in
+    repos/acme/widgets/branches/fix/github-checks)
+        printf '%s\n' '0123456789abcdef0123456789abcdef01234567'
+        ;;
+    repos/acme/widgets/commits/*/statuses?per_page=100)
+        printf '%s\n' '[[]]'
+        ;;
+    repos/acme/widgets/commits/*/check-runs?per_page=100\&filter=latest)
+        case "${MOSAIC_GH_CHECK_MODE:?}" in
+            success) printf '%s\n' '[{"total_count":1,"check_runs":[{"name":"ci","status":"completed","conclusion":"success"}]}]' ;;
+            pending) printf '%s\n' '[{"total_count":1,"check_runs":[{"name":"ci","status":"in_progress","conclusion":null}]}]' ;;
+            failure) printf '%s\n' '[{"total_count":1,"check_runs":[{"name":"ci","status":"completed","conclusion":"failure"}]}]' ;;
+            late-failure) printf '%s\n' '[{"total_count":2,"check_runs":[{"name":"first-page","status":"completed","conclusion":"success"}]},{"total_count":2,"check_runs":[{"name":"later-page","status":"completed","conclusion":"failure"}]}]' ;;
+            *) exit 2 ;;
+        esac
+        ;;
+    *) echo "unexpected gh endpoint: $endpoint" >&2; exit 2 ;;
+esac
+SH
+chmod +x "$STUB_DIR/gh"
+
+run_guard() {
+    local mode="$1"
+    (
+        cd "$REPO_DIR" || exit
+        export PATH="$STUB_DIR:$PATH"
+        export MOSAIC_GH_CHECK_MODE="$mode"
+        export MOSAIC_GH_CALL_LOG="$WORK_DIR/gh-calls.log"
+        export MOSAIC_CI_QUEUE_AUDIT_LOG="$WORK_DIR/audit.jsonl"
+        "$SCRIPT_DIR/ci-queue-wait.sh" --purpose push -t 0 -i 0
+    )
+}
+
+failures=0
+assert_case() {
+    local mode="$1" expected_rc="$2" expected_state="$3" output rc
+    set +e
+    output=$(run_guard "$mode" 2>&1)
+    rc=$?
+    set -e
+    if [[ "$expected_rc" == zero && "$rc" -ne 0 ]]; then
+        echo "FAIL github-$mode: expected rc=0, got $rc" >&2
+        failures=$((failures + 1))
+    elif [[ "$expected_rc" == nonzero && "$rc" -eq 0 ]]; then
+        echo "FAIL github-$mode: expected rc!=0, got 0" >&2
+        failures=$((failures + 1))
+    fi
+    if [[ "$output" != *"state=$expected_state"* ]]; then
+        echo "FAIL github-$mode: expected state=$expected_state, got:" >&2
+        printf '%s\n' "$output" >&2
+        failures=$((failures + 1))
+    fi
+}
+
+set -e
+: > "$WORK_DIR/gh-calls.log"
+assert_case success zero terminal-success
+assert_case pending nonzero pending
+assert_case failure nonzero terminal-failure
+assert_case late-failure nonzero terminal-failure
+
+if [[ $(grep -c 'check-runs?per_page=100&filter=latest' "$WORK_DIR/gh-calls.log") -lt 4 ]]; then
+    echo "FAIL: expected every case to query all Checks API pages" >&2
+    failures=$((failures + 1))
+fi
+
+if [[ "$failures" -ne 0 ]]; then
+    echo "GitHub check-runs regression failed ($failures assertions)" >&2
+    exit 1
+fi
+
+echo "GitHub check-runs regression passed (4/4 cases, including later-page failure)"
@@ -0,0 +1,232 @@
+#!/usr/bin/env bash
+# Exit-asserting RM-03 regression harness for ci-queue-wait.sh.
+# Every case is a process-level assertion: a classifier-only green cannot satisfy it.
+
+set -u
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/ci-queue-wait-tristate}"
+REPO_DIR="$WORK_DIR/repo"
+STUB_DIR="$WORK_DIR/stubs"
+AUDIT_LOG="$WORK_DIR/audit/ci-queue-wait.jsonl"
+FEATURE_BRANCH="fix/rm-03-fixture"
+
+rm -rf "$WORK_DIR"
+mkdir -p "$REPO_DIR" "$STUB_DIR"
+git -C "$REPO_DIR" init -q
+git -C "$REPO_DIR" checkout -q -b "$FEATURE_BRANCH"
+git -C "$REPO_DIR" remote add origin https://git.example.test/acme/widgets.git
+
+cat > "$STUB_DIR/curl" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+
+url=""
+has_write_out=0
+for arg in "$@"; do
+    case "$arg" in
+        -w) has_write_out=1 ;;
+        http://*|https://*) url="$arg" ;;
+    esac
+done
+printf '%s\n' "$url" >> "${MOSAIC_STUB_URL_LOG:?}"
+
+case "$url" in
+    */branches/*)
+        if [[ "${MOSAIC_STUB_BRANCH_MODE:-ok}" == "unreachable" ]]; then
+            exit 7
+        fi
+        body='{"commit":{"id":"deadbeefcafef00d0123456789abcdef01234567"}}'
+        if [[ "$has_write_out" -eq 1 ]]; then
+            printf '%s\n200' "$body"
+        else
+            printf '%s' "$body"
+        fi
+        ;;
+    */status)
+        case "${MOSAIC_STUB_STATUS_MODE:?}" in
+            success)   printf '%s' '{"state":"success","statuses":[{"status":"success"}]}' ;;
+            pending)   printf '%s' '{"state":"pending","statuses":[{"status":"pending","context":"ci/test"}]}' ;;
+            failure)   printf '%s' '{"state":"failure","statuses":[{"status":"failure"}]}' ;;
+            no-status) printf '%s' '{"state":"","statuses":[]}' ;;
+            aggregate-success-no-status) printf '%s' '{"state":"success","statuses":[]}' ;;
+            malformed) printf '%s' 'not-json' ;;
+            malformed-statuses-type) printf '%s' '{"state":"success","statuses":"corrupt"}' ;;
+            malformed-status-entry) printf '%s' '{"state":"success","statuses":[null]}' ;;
+            large-success)
+                python3 -c 'import json; print(json.dumps({"state":"success", "statuses":[{"status":"success"}], "padding":"x" * (160 * 1024)}), end="")'
+                ;;
+            unreachable) exit 7 ;;
+            *) echo "unknown status mode" >&2; exit 2 ;;
+        esac
+        ;;
+    *) echo "unexpected curl URL: $url" >&2; exit 2 ;;
+esac
+SH
+chmod +x "$STUB_DIR/curl"
+
+run_guard() {
+    local status_mode="$1"
+    local audit_log="${2:-$AUDIT_LOG}"
+    shift 2 || true
+    (
+        cd "$REPO_DIR" || exit
+        export PATH="$STUB_DIR:$PATH"
+        export MOSAIC_CREDENTIALS_FILE="$WORK_DIR/no-credentials.json"
+        if [[ "$status_mode" == "credential-unresolvable" ]]; then
+            export HOME="$WORK_DIR/empty-home"
+            mkdir -p "$HOME"
+            unset GITEA_TOKEN GITEA_URL MOSAIC_GIT_IDENTITY
+            export MOSAIC_STUB_STATUS_MODE=success
+        else
+            export GITEA_TOKEN=stub-token
+            export GITEA_URL=https://git.example.test
+            export MOSAIC_STUB_STATUS_MODE="$status_mode"
+        fi
+        export MOSAIC_STUB_URL_LOG="$WORK_DIR/urls.log"
+        export MOSAIC_CI_QUEUE_AUDIT_LOG="$audit_log"
+        "$SCRIPT_DIR/ci-queue-wait.sh" --purpose "${MOSAIC_TEST_PURPOSE:-push}" -t 0 -i 0 "$@"
+    )
+}
+
+failures=0
+run_assertion() {
+    local name="$1" expected_rc="$2" status_mode="$3" required_text="$4"
+    local output rc
+    shift 4
+    set +e
+    output=$(run_guard "$status_mode" "$AUDIT_LOG" "$@" 2>&1)
+    rc=$?
+    set -e
+
+    case "$expected_rc" in
+        zero)
+            if [[ "$rc" -ne 0 ]]; then
+                echo "FAIL $name: expected rc=0, got rc=$rc" >&2
+                failures=$((failures + 1))
+            fi
+            ;;
+        nonzero)
+            if [[ "$rc" -eq 0 ]]; then
+                echo "FAIL $name: expected rc!=0, got rc=0" >&2
+                failures=$((failures + 1))
+            fi
+            ;;
+        not126)
+            if [[ "$rc" -eq 126 ]]; then
+                echo "FAIL $name: payload transport hit ARG_MAX (rc=126)" >&2
+                failures=$((failures + 1))
+            fi
+            ;;
+    esac
+    if [[ "$output" != *"$required_text"* ]]; then
+        echo "FAIL $name: output missing '$required_text' (rc=$rc)" >&2
+        printf '%s\n' "$output" >&2
+        failures=$((failures + 1))
+    fi
+}
+
+set -e
+: > "$WORK_DIR/urls.log"
+run_assertion success zero success 'state=terminal-success'
+run_assertion pending nonzero pending 'ASSERTED_NOT_READY'
+run_assertion failure nonzero failure 'ASSERTED_NOT_READY'
+run_assertion no-status nonzero no-status 'ASSERTED_NOT_READY'
+run_assertion aggregate-success-no-status nonzero aggregate-success-no-status 'ASSERTED_NOT_READY'
+run_assertion malformed nonzero malformed 'ASSERTED_NOT_READY'
+run_assertion malformed-statuses-type nonzero malformed-statuses-type 'ASSERTED_NOT_READY'
+run_assertion malformed-status-entry nonzero malformed-status-entry 'ASSERTED_NOT_READY'
+run_assertion large-payload not126 large-success 'state=terminal-success'
+run_assertion credential-unresolvable zero credential-unresolvable 'CANNOT_ASSERT'
+run_assertion provider-unreachable zero unreachable 'CANNOT_ASSERT'
+
+if [[ ! -s "$AUDIT_LOG" ]] || ! grep -q '"outcome":"CANNOT_ASSERT"' "$AUDIT_LOG"; then
+    echo "FAIL provider-unreachable-audit: expected durable CANNOT_ASSERT JSONL record" >&2
+    failures=$((failures + 1))
+fi
+
+# Merge cannot proceed without exact-head evidence. CANNOT_ASSERT is retryable exit 75,
+# distinct from ASSERTED_NOT_READY (3/124), and still writes its audit record.
+merge_audit_lines_before=$(wc -l < "$AUDIT_LOG")
+set +e
+merge_unreachable_output=$(MOSAIC_TEST_PURPOSE=merge run_guard unreachable "$AUDIT_LOG" 2>&1)
+merge_unreachable_rc=$?
+set -e
+if [[ "$merge_unreachable_rc" -ne 75 ]]; then
+    echo "FAIL merge-provider-unreachable: expected rc=75, got rc=$merge_unreachable_rc" >&2
+    failures=$((failures + 1))
+fi
+if [[ "$merge_unreachable_output" != *"CANNOT_ASSERT"* ]]; then
+    echo "FAIL merge-provider-unreachable: expected loud CANNOT_ASSERT diagnostic" >&2
+    failures=$((failures + 1))
+fi
+merge_audit_lines_after=$(wc -l < "$AUDIT_LOG")
+if [[ "$merge_audit_lines_after" -le "$merge_audit_lines_before" ]]; then
+    echo "FAIL merge-provider-unreachable: expected an additional audit record" >&2
+    failures=$((failures + 1))
+fi
+
+# A feature-branch push with no -B must inspect the checked-out feature branch.
+if ! grep -q "/branches/$FEATURE_BRANCH" "$WORK_DIR/urls.log"; then
+    echo "FAIL implicit-branch: provider was not queried for $FEATURE_BRANCH" >&2
+    failures=$((failures + 1))
+fi
+
+# Merge callers can pin both a fork repository and the exact reviewed head SHA.
+exact_sha=0123456789abcdef0123456789abcdef01234567
+: > "$WORK_DIR/urls.log"
+run_assertion exact-fork-head zero success 'state=terminal-success' \
+    -B fix/rm-03-fixture -R contributor/widgets-fork --sha "$exact_sha"
+if ! grep -q "/repos/contributor/widgets-fork/commits/$exact_sha/status" "$WORK_DIR/urls.log"; then
+    echo "FAIL exact-fork-head: status URL did not bind fork repository and exact SHA" >&2
+    failures=$((failures + 1))
+fi
+if grep -q '/branches/' "$WORK_DIR/urls.log"; then
+    echo "FAIL exact-fork-head: explicit SHA must not be re-resolved through a branch" >&2
+    failures=$((failures + 1))
+fi
+
+# Platform/repository discovery failures use the same audited CANNOT_ASSERT path.
+audit_lines_before=$(wc -l < "$AUDIT_LOG")
+git -C "$REPO_DIR" remote set-url origin https://gitlab.com/acme/widgets.git
+set +e
+unsupported_output=$(run_guard success "$AUDIT_LOG" 2>&1)
+unsupported_rc=$?
+set -e
+git -C "$REPO_DIR" remote set-url origin https://git.example.test/acme/widgets.git
+if [[ "$unsupported_rc" -ne 0 ]]; then
+    echo "FAIL unsupported-platform: expected degraded rc=0, got rc=$unsupported_rc" >&2
+    failures=$((failures + 1))
+fi
+if [[ "$unsupported_output" != *"CANNOT_ASSERT"* ]]; then
+    echo "FAIL unsupported-platform: expected loud CANNOT_ASSERT diagnostic" >&2
+    failures=$((failures + 1))
+fi
+audit_lines_after=$(wc -l < "$AUDIT_LOG")
+if [[ "$audit_lines_after" -le "$audit_lines_before" ]]; then
+    echo "FAIL unsupported-platform: expected an additional audit record" >&2
+    failures=$((failures + 1))
+fi
+
+# A degraded pass is forbidden if the audit receipt cannot be written.
+mkdir -p "$WORK_DIR/not-a-directory"
+printf 'file' > "$WORK_DIR/not-a-directory/parent"
+set +e
+audit_failure_output=$(run_guard unreachable "$WORK_DIR/not-a-directory/parent/audit.jsonl" 2>&1)
+audit_failure_rc=$?
+set -e
+if [[ "$audit_failure_rc" -eq 0 ]]; then
+    echo "FAIL audit-unavailable: expected rc!=0, got rc=0" >&2
+    failures=$((failures + 1))
+fi
+if [[ "$audit_failure_output" != *"audit"* ]]; then
+    echo "FAIL audit-unavailable: expected loud audit failure diagnostic" >&2
+    failures=$((failures + 1))
+fi
+
+if [[ "$failures" -ne 0 ]]; then
+    echo "ci-queue-wait tri-state regression failed ($failures assertions)" >&2
+    exit 1
+fi
+
+echo "ci-queue-wait tri-state regression passed (all outcome classes)"
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Regression harness for pr-merge.sh Gitea non-interactive tea empty identity fallback.
+# Regression harness for pr-merge.sh Gitea exact-head API path and input safety.

 set -euo pipefail

@@ -79,15 +79,24 @@ emit_response() {
        printf '200'
    fi
 }
+if [[ "$args" == *"/api/v1/repos/mosaicstack/stack/commits/0123456789abcdef0123456789abcdef01234567/status"* ]]; then
+    emit_response '{"state":"success","statuses":[{"context":"ci/test","status":"success"}]}'
+    exit 0
+fi
 if [[ "$args" == *"/api/v1/repos/mosaicstack/stack/pulls/123"* && "$args" != *"/api/v1/repos/mosaicstack/stack/pulls/123/merge"* ]]; then
-    emit_response '{"number":123,"title":"mock","state":"open","user":{"login":"tester"},"head":{"ref":"feature/mock"},"base":{"ref":"main"},"labels":[],"assignees":[],"html_url":"https://git.mosaicstack.dev/mosaicstack/stack/pulls/123","mergeable":true}'
+    emit_response '{"number":123,"title":"mock","state":"open","user":{"login":"tester"},"head":{"ref":"feature/mock","sha":"0123456789abcdef0123456789abcdef01234567","repo":{"full_name":"mosaicstack/stack"}},"base":{"ref":"main"},"labels":[],"assignees":[],"html_url":"https://git.mosaicstack.dev/mosaicstack/stack/pulls/123","mergeable":true}'
    exit 0
 fi
 if [[ "$args" == *"-X POST"* && "$args" == *"/api/v1/repos/mosaicstack/stack/pulls/123/merge"* ]]; then
-    if [[ "$post_data" != '{"Do":"squash"}' ]]; then
-        echo "unexpected merge payload: $post_data" >&2
-        exit 96
-    fi
+    POST_DATA="$post_data" python3 - <<'PY'
+import json
+import os
+payload = json.loads(os.environ["POST_DATA"])
+assert payload == {
+    "Do": "squash",
+    "head_commit_id": "0123456789abcdef0123456789abcdef01234567",
+}, payload
+PY
    emit_response '{"merged":true,"message":"mock merge complete"}'
    exit 0
 fi
@@ -107,8 +116,8 @@ export GITEA_URL="https://git.mosaicstack.dev"
 export GITEA_TOKEN="redacted-test-token"

 OUTPUT="$SANDBOX/output.log"
-if ! "$SCRIPT_DIR/pr-merge.sh" -n 123 -m squash --skip-queue-guard > "$OUTPUT" 2>&1; then
-    echo "Expected pr-merge.sh to recover via Gitea API fallback." >&2
+if ! "$SCRIPT_DIR/pr-merge.sh" -n 123 -m squash > "$OUTPUT" 2>&1; then
+    echo "Expected pr-merge.sh to use the exact-head Gitea API path." >&2
    echo "--- output ---" >&2
    sed 's/redacted-test-token/***REDACTED***/g' "$OUTPUT" >&2
    echo "--- mock log ---" >&2
@@ -127,38 +136,6 @@ if grep -q 'redacted-test-token' "$OUTPUT"; then
    exit 1
 fi

-cat > "$MOCK_BIN/tea" <<'EOF'
-#!/bin/bash
-set -euo pipefail
-printf 'tea %q ' "$@" >> "$PR_MERGE_TEST_LOG"
-printf '\n' >> "$PR_MERGE_TEST_LOG"
-if [[ "$*" == *"login list"* ]]; then
-    echo '[{"name":"git.mosaicstack.dev","url":"https://git.mosaicstack.dev"}]'
-    exit 0
-fi
-if [[ "$*" == *"pr merge"* ]]; then
-    echo 'tea network timeout' >&2
-    exit 2
-fi
-exit 0
-EOF
-chmod +x "$MOCK_BIN/tea"
-: > "$LOG_FILE"
-if "$SCRIPT_DIR/pr-merge.sh" -n 123 -m squash --skip-queue-guard > "$OUTPUT" 2>&1; then
-    echo "Expected arbitrary tea failure to remain blocking." >&2
-    exit 1
-fi
-if grep -q '/api/v1/repos/mosaicstack/stack/pulls/123/merge' "$LOG_FILE"; then
-    echo "Arbitrary tea failure unexpectedly used Gitea API merge fallback." >&2
-    sed 's/redacted-test-token/***REDACTED***/g' "$LOG_FILE" >&2
-    exit 1
-fi
-if ! grep -q 'tea network timeout' "$OUTPUT"; then
-    echo "Expected arbitrary tea error to be preserved in output." >&2
-    sed 's/redacted-test-token/***REDACTED***/g' "$OUTPUT" >&2
-    exit 1
-fi
-
 cat > "$MOCK_BIN/tea" <<'EOF'
 #!/bin/bash
 set -euo pipefail
@@ -177,8 +154,8 @@ EOF
 chmod +x "$MOCK_BIN/tea"
 unset GITEA_LOGIN
 : > "$LOG_FILE"
-if ! "$SCRIPT_DIR/pr-merge.sh" -n 123 -m squash --skip-queue-guard > "$OUTPUT" 2>&1; then
-    echo "Expected missing tea login to use authenticated Gitea API fallback." >&2
+if ! "$SCRIPT_DIR/pr-merge.sh" -n 123 -m squash > "$OUTPUT" 2>&1; then
+    echo "Expected the exact-head API path not to depend on a tea login." >&2
    sed 's/redacted-test-token/***REDACTED***/g' "$OUTPUT" >&2
    sed 's/redacted-test-token/***REDACTED***/g' "$LOG_FILE" >&2
    exit 1
@@ -215,7 +192,7 @@ cd "$REPO_DIR"
 git remote set-url origin https://github.com/mosaicstack/stack.git
 : > "$LOG_FILE"
 rm -f "$SENTINEL"
-if "$SCRIPT_DIR/pr-merge.sh" -n "$INJECTION" -m squash --skip-queue-guard > "$OUTPUT" 2>&1; then
+if "$SCRIPT_DIR/pr-merge.sh" -n "$INJECTION" -m squash > "$OUTPUT" 2>&1; then
    echo "Expected GitHub metacharacter PR number to be rejected." >&2
    sed 's/redacted-test-token/***REDACTED***/g' "$OUTPUT" >&2
    exit 1
@@ -240,7 +217,7 @@ git remote set-url origin https://git.mosaicstack.dev/mosaicstack/stack.git
 export GITEA_LOGIN="git.mosaicstack.dev"
 : > "$LOG_FILE"
 rm -f "$SENTINEL"
-if "$SCRIPT_DIR/pr-merge.sh" -n "$INJECTION" -m squash --skip-queue-guard > "$OUTPUT" 2>&1; then
+if "$SCRIPT_DIR/pr-merge.sh" -n "$INJECTION" -m squash > "$OUTPUT" 2>&1; then
    echo "Expected Gitea metacharacter PR number to be rejected." >&2
    sed 's/redacted-test-token/***REDACTED***/g' "$OUTPUT" >&2
    exit 1
@@ -260,4 +237,4 @@ if ! grep -q 'Invalid PR number' "$OUTPUT"; then
    exit 1
 fi

-echo "pr-merge.sh Gitea fallback regression passed"
+echo "pr-merge.sh Gitea exact-head API regression passed"
@@ -0,0 +1,156 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC2030,SC2031 # Provider arms isolate PATH/credentials in subshells.
+# The commit whose CI was guarded must be the commit the provider atomically merges.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-merge-head-pin}"
+SHA=0123456789abcdef0123456789abcdef01234567
+
+make_fixture() {
+    local name="$1" remote="$2"
+    local root="$WORK_DIR/$name"
+    local tools="$root/tools/git"
+    mkdir -p "$tools" "$root/repo"
+    cp "$SCRIPT_DIR/pr-merge.sh" "$tools/pr-merge.sh"
+    cp "$SCRIPT_DIR/detect-platform.sh" "$tools/detect-platform.sh"
+    git -C "$root/repo" init -q
+    git -C "$root/repo" remote add origin "$remote"
+    cat > "$tools/pr-metadata.sh" <<SH
+#!/usr/bin/env bash
+printf '%s\n' '{"baseRefName":"main","headRefName":"fix/pinned","headRefOid":"$SHA","headRepository":"contributor/widgets-fork"}'
+SH
+    cat > "$tools/ci-queue-wait.sh" <<'SH'
+#!/usr/bin/env bash
+exit 0
+SH
+    chmod +x "$tools"/*.sh
+}
+
+rm -rf "$WORK_DIR"
+make_fixture gitea https://git.example.test/acme/widgets.git
+make_fixture github https://github.com/acme/widgets.git
+
+cat > "$WORK_DIR/gitea/curl" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+payload=""
+for ((i=1; i<=$#; i++)); do
+    if [[ "${!i}" == "-d" ]]; then
+        j=$((i + 1))
+        payload="${!j}"
+    fi
+done
+printf '%s' "$payload" > "${MOSAIC_MERGE_PAYLOAD_LOG:?}"
+printf '200'
+SH
+chmod +x "$WORK_DIR/gitea/curl"
+
+set +e
+(
+    cd "$WORK_DIR/gitea/repo"
+    export PATH="$WORK_DIR/gitea:$PATH"
+    export GITEA_TOKEN=stub-token
+    export GITEA_URL=https://git.example.test
+    export MOSAIC_CREDENTIALS_FILE="$WORK_DIR/no-credentials.json"
+    export MOSAIC_MERGE_PAYLOAD_LOG="$WORK_DIR/gitea-payload.json"
+    env -u MOSAIC_GIT_IDENTITY "$WORK_DIR/gitea/tools/git/pr-merge.sh" -n 123
+) >"$WORK_DIR/gitea.out" 2>&1
+gitea_rc=$?
+set -e
+if [[ "$gitea_rc" -ne 0 ]]; then
+    echo "FAIL gitea-pin: merge fixture returned $gitea_rc" >&2
+    cat "$WORK_DIR/gitea.out" >&2
+    exit 1
+fi
+python3 - "$WORK_DIR/gitea-payload.json" "$SHA" <<'PY'
+import json
+import sys
+payload = json.load(open(sys.argv[1], encoding="utf-8"))
+assert set(payload) <= {"Do", "head_commit_id", "delete_branch_after_merge"}, payload
+assert payload.get("Do") == "squash", payload
+assert payload.get("head_commit_id") == sys.argv[2], payload
+PY
+
+# A merge-gate verdict is commit-bound. A stale expected head must fail before merge.
+wrong_sha=ffffffffffffffffffffffffffffffffffffffff
+rm -f "$WORK_DIR/gitea-payload-stale.json"
+set +e
+(
+    cd "$WORK_DIR/gitea/repo"
+    export PATH="$WORK_DIR/gitea:$PATH"
+    export GITEA_TOKEN=stub-token
+    export GITEA_URL=https://git.example.test
+    export MOSAIC_CREDENTIALS_FILE="$WORK_DIR/no-credentials.json"
+    export MOSAIC_MERGE_PAYLOAD_LOG="$WORK_DIR/gitea-payload-stale.json"
+    env -u MOSAIC_GIT_IDENTITY "$WORK_DIR/gitea/tools/git/pr-merge.sh" -n 123 --expect-head "$wrong_sha"
+) >"$WORK_DIR/gitea-stale.out" 2>&1
+stale_rc=$?
+set -e
+if [[ "$stale_rc" -eq 0 ]] || [[ -e "$WORK_DIR/gitea-payload-stale.json" ]]; then
+    echo "FAIL stale-verdict: moved head was not refused before provider merge" >&2
+    exit 1
+fi
+
+# A merge-capable path cannot bypass the mandatory queue guard. The legacy
+# --skip-queue-guard option must be rejected before any provider merge call.
+cat > "$WORK_DIR/gitea/tools/git/ci-queue-wait.sh" <<'SH'
+#!/usr/bin/env bash
+exit 99
+SH
+chmod +x "$WORK_DIR/gitea/tools/git/ci-queue-wait.sh"
+rm -f "$WORK_DIR/gitea-payload-bypass.json"
+set +e
+(
+    cd "$WORK_DIR/gitea/repo"
+    export PATH="$WORK_DIR/gitea:$PATH"
+    export GITEA_TOKEN=stub-token
+    export GITEA_URL=https://git.example.test
+    export MOSAIC_CREDENTIALS_FILE="$WORK_DIR/no-credentials.json"
+    export MOSAIC_MERGE_PAYLOAD_LOG="$WORK_DIR/gitea-payload-bypass.json"
+    env -u MOSAIC_GIT_IDENTITY "$WORK_DIR/gitea/tools/git/pr-merge.sh" -n 123 --skip-queue-guard
+) >"$WORK_DIR/gitea-bypass.out" 2>&1
+bypass_rc=$?
+set -e
+if [[ "$bypass_rc" -eq 0 ]] || [[ -e "$WORK_DIR/gitea-payload-bypass.json" ]]; then
+    echo "FAIL merge-bypass: --skip-queue-guard reached the provider merge path" >&2
+    exit 1
+fi
+
+# Dry-run is the only path that may omit the guard because it exits before the
+# provider merge dispatch. Prove the exit and absence of a merge payload.
+rm -f "$WORK_DIR/gitea-payload-dry-run.json"
+(
+    cd "$WORK_DIR/gitea/repo"
+    export PATH="$WORK_DIR/gitea:$PATH"
+    export GITEA_TOKEN=stub-token
+    export GITEA_URL=https://git.example.test
+    export MOSAIC_CREDENTIALS_FILE="$WORK_DIR/no-credentials.json"
+    export MOSAIC_MERGE_PAYLOAD_LOG="$WORK_DIR/gitea-payload-dry-run.json"
+    env -u MOSAIC_GIT_IDENTITY "$WORK_DIR/gitea/tools/git/pr-merge.sh" -n 123 --dry-run
+) >"$WORK_DIR/gitea-dry-run.out" 2>&1
+if [[ -e "$WORK_DIR/gitea-payload-dry-run.json" ]]; then
+    echo "FAIL dry-run: non-merging preflight reached the provider merge path" >&2
+    exit 1
+fi
+
+cat > "$WORK_DIR/github/gh" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+printf '%s\n' "$*" > "${MOSAIC_GH_MERGE_LOG:?}"
+SH
+chmod +x "$WORK_DIR/github/gh"
+(
+    cd "$WORK_DIR/github/repo"
+    export PATH="$WORK_DIR/github:$PATH"
+    export MOSAIC_GH_MERGE_LOG="$WORK_DIR/github-call.log"
+    "$WORK_DIR/github/tools/git/pr-merge.sh" -n 123
+) >"$WORK_DIR/github.out" 2>&1
+if ! grep -q -- "--match-head-commit $SHA" "$WORK_DIR/github-call.log"; then
+    echo "FAIL github-pin: merge command omitted --match-head-commit $SHA" >&2
+    cat "$WORK_DIR/github-call.log" >&2
+    exit 1
+fi
+
+echo "PR merge exact-head pin regression passed (Gitea + GitHub)"
@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+# RM-03: pr-merge must guard the PR head branch, not its main base branch.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-merge-queue-branch}"
+FIXTURE_DIR="$WORK_DIR/tools/git"
+CALL_LOG="$WORK_DIR/queue-call.log"
+
+rm -rf "$WORK_DIR"
+mkdir -p "$FIXTURE_DIR"
+cp "$SCRIPT_DIR/pr-merge.sh" "$FIXTURE_DIR/pr-merge.sh"
+cp "$SCRIPT_DIR/detect-platform.sh" "$FIXTURE_DIR/detect-platform.sh"
+
+cat > "$FIXTURE_DIR/pr-metadata.sh" <<'SH'
+#!/usr/bin/env bash
+printf '%s\n' '{"baseRefName":"main","headRefName":"fix/rm-03-fixture","headRefOid":"0123456789abcdef0123456789abcdef01234567","headRepository":"contributor/widgets-fork"}'
+SH
+
+cat > "$FIXTURE_DIR/ci-queue-wait.sh" <<'SH'
+#!/usr/bin/env bash
+printf '%s\n' "$*" > "${MOSAIC_QUEUE_CALL_LOG:?}"
+exit 42
+SH
+chmod +x "$FIXTURE_DIR"/*.sh
+
+set +e
+(
+    cd "$WORK_DIR"
+    export MOSAIC_QUEUE_CALL_LOG="$CALL_LOG"
+    "$FIXTURE_DIR/pr-merge.sh" -n 123
+) >/dev/null 2>&1
+rc=$?
+set -e
+
+if [[ "$rc" -ne 42 ]]; then
+    echo "FAIL: expected queue stub rc=42 to propagate, got $rc" >&2
+    exit 1
+fi
+if [[ ! -s "$CALL_LOG" ]]; then
+    echo "FAIL: merge wrapper did not invoke the queue guard" >&2
+    exit 1
+fi
+if ! grep -q -- '-B fix/rm-03-fixture' "$CALL_LOG"; then
+    echo "FAIL: merge queue guard did not receive PR head branch" >&2
+    cat "$CALL_LOG" >&2
+    exit 1
+fi
+if grep -q -- '-B main' "$CALL_LOG"; then
+    echo "FAIL: merge queue guard still received the main base branch" >&2
+    cat "$CALL_LOG" >&2
+    exit 1
+fi
+if ! grep -q -- '-R contributor/widgets-fork' "$CALL_LOG"; then
+    echo "FAIL: merge queue guard did not receive the fork head repository" >&2
+    cat "$CALL_LOG" >&2
+    exit 1
+fi
+if ! grep -q -- '--sha 0123456789abcdef0123456789abcdef01234567' "$CALL_LOG"; then
+    echo "FAIL: merge queue guard did not receive the exact PR head SHA" >&2
+    cat "$CALL_LOG" >&2
+    exit 1
+fi
+
+echo "pr-merge queue branch/repository/SHA regression passed"
@@ -25,7 +25,7 @@
    "lint": "eslint src",
    "typecheck": "tsc --noEmit",
    "test": "vitest run --passWithNoTests && pnpm run test:framework-shell",
-    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh"
+    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh"
  },
  "dependencies": {
    "@mosaicstack/brain": "workspace:*",