# 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

- [x] 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`.
- [x] Final approval requires an exact draft version.
- [x] High-risk unsupported claims block approval.
- [x] Missing required publishing settings block approval.
- [x] Unapproved required assets block approval.
- [x] Approval writes a workflow event with actor, timestamp, draft version, and publishing settings.
- [x] Revision request writes event and moves article to `FINAL_REVISION_REQUIRED`.
- [x] 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: Done (TDD RED -> GREEN completed).
- TDD progression:
  1. Pre-requirement RED test created for high-risk unsupported claims blocker.
  2. Implemented final approval gate service with checklist evaluation on assembled draft + evidence + assets + review state.
  3. Added public endpoints:
     - `POST /api/articles/{article_id}/final-approval`
     - `POST /api/articles/{article_id}/final-revision-request`
     - `GET /api/articles/{article_id}/final-approval/checklist` (for UI checklist visibility).
  4. Added workflow events:
     - `FINAL_APPROVAL_GRANTED` -> `PUBLISH_DRY_RUN_REQUIRED`
     - `FINAL_REVISION_REQUESTED` -> `FINAL_REVISION_REQUIRED`
  5. Added frontend final-approval feature (FSD) to show blockers/completed checklist items and invoke approval/revision endpoints.

- Implemented behavior coverage:
  - Exact draft version is required and validated against latest immutable draft.
  - High-risk unsupported claims (claims + section scaffold history) block approval.
  - Missing required publishing settings (`frontmatter`, `content_path`, `author`, `publishing_mode`) block approval.
  - Unapproved required assets block approval.
  - Successful approval writes event payload with actor/timestamp/draft version/publishing settings and moves state to `PUBLISH_DRY_RUN_REQUIRED`.
  - Revision request writes event payload and moves state to `FINAL_REVISION_REQUIRED`.
  - UI renders checklist rows, blockers, and completed items.

- Verification output:
  - `PYTHONPATH=/private/tmp/pupline-backend-deps python3 -m unittest apps/backend/tests/integration/test_final_approval_gate_public_api.py` -> OK (7 tests)
  - `PYTHONPATH=/private/tmp/pupline-backend-deps python3 -m unittest apps/backend/tests/integration/test_seo_language_review_public_api.py` -> OK (6 tests)
  - `PYTHONPATH=/private/tmp/pupline-backend-deps python3 -m unittest apps/backend/tests/integration/test_assets_media_library_public_api.py` -> OK (7 tests)
  - `PYTHONPATH=/private/tmp/pupline-backend-deps python3 -m unittest apps/backend/tests/integration/test_draft_assembly_public_api.py` -> OK (5 tests)
  - `node apps/frontend/tests/final_approval.model.test.mjs` -> OK
  - `pnpm --dir apps/frontend typecheck` -> OK