# Task 016: Final Approval Gate

Development description: Implement the final review gate that prevents publishing until the editor has approved the exact draft version, assets, evidence state, metadata, and publishing settings.

## Implementation Details

- Backend endpoints:
  - `POST /api/articles/{article_id}/final-approval`
  - `POST /api/articles/{article_id}/final-revision-request`
- Final approval checklist:
  - Plan followed.
  - Evidence reviewed.
  - No high-risk unsupported claims remain.
  - SEO metadata approved.
  - Images/assets approved.
  - Tables and diagrams approved.
  - Internal links approved.
  - Frontmatter fields selected.
  - Content path selected.
  - Author selected.
  - Publishing mode selected.
- Approval records:
  - Actor.
  - Timestamp.
  - Exact draft version.
  - Selected publishing settings.
- Revision request returns workflow to `FINAL_REVISION_REQUIRED`.

## Public Interface

- Editor sees final review checklist.
- Editor cannot approve while hard blockers remain.
- Approved article moves to `PUBLISH_DRY_RUN_REQUIRED`.

## Acceptance Criteria

- [ ] TDD pre-requirement: before implementation, write one failing behavior test proving high-risk unsupported claims block final approval; proceed one checklist behavior at a time and record evidence in `Result`.
- [ ] Final approval requires an exact draft version.
- [ ] High-risk unsupported claims block approval.
- [ ] Missing required publishing settings block approval.
- [ ] Unapproved required assets block approval.
- [ ] Approval writes a workflow event with actor, timestamp, draft version, and publishing settings.
- [ ] Revision request writes event and moves article to `FINAL_REVISION_REQUIRED`.
- [ ] UI shows blockers and completed checklist items.

## Verification

- Run final approval API tests.
- Run frontend final review tests.
- Run smoke flow showing blocked and successful approval paths.

## Result

- Status: Pending execution.
- TDD plan: To be filled during execution.
- Red evidence: To be filled during execution.
- Green evidence: To be filled during execution.
- Refactor notes: To be filled during execution.
- Verification output: To be filled during execution.