# Task 009: Plan Generation And Review Gate

Development description: Implement article plan generation, immutable plan versioning, direct plan edits, revision requests, and final plan approval before research.

## Implementation Details

- Backend endpoints:
  - `POST /api/articles/{article_id}/plan/generate`
  - `GET /api/articles/{article_id}/plans`
  - `GET /api/articles/{article_id}/plans/{plan_id}`
  - `PATCH /api/articles/{article_id}/plans/{plan_id}`
  - `POST /api/articles/{article_id}/plans/{plan_id}/approve`
  - `POST /api/articles/{article_id}/plans/{plan_id}/request-revision`
- Plan generation uses:
  - Brief.
  - Boundary answers.
  - Target site config.
  - Output schema.
- Plan must include:
  - Title options.
  - Recommended title.
  - Reader persona.
  - Search intent.
  - Thesis.
  - At least four sections.
  - Claims to prove.
  - Evidence needs.
  - Visual needs.
  - SEO notes.
  - Risks.
- Edits create new immutable versions rather than mutating approval-relevant content in place.
- Research cannot start until plan is approved.

## Public Interface

- Editor generates a plan.
- Editor edits, requests revision, or approves the plan.
- Approved plan becomes the production contract for research.

## Acceptance Criteria

- [ ] TDD pre-requirement: before implementation, write one failing public API test showing research cannot start before plan approval; implement generation/review behavior in vertical cycles and record evidence in `Result`.
- [ ] Plan generation creates version 1 and moves article to `PLAN_REVIEW_REQUIRED`.
- [ ] Plan has at least four sections with purpose, key points, and evidence needs.
- [ ] Direct plan edit creates a new immutable version.
- [ ] Revision request writes workflow event and returns workflow to plan generation/revision.
- [ ] Approval writes workflow event with actor, timestamp, and exact plan version.
- [ ] Previous plan versions remain accessible.
- [ ] Frontend supports approve, request revision, direct edit, section notes, source requirements, excluded sources, visual requirements, tone, audience, and SEO keyword changes.

## Verification

- Run plan API integration tests with fake runner output.
- Run frontend plan review tests.
- Run a Docker Compose smoke flow through plan approval.

## 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.