# Task 011: Evidence Matrix And Claim Gate

Development description: Build claim extraction, claim-to-evidence mapping, unsupported-claim visibility, insufficient-evidence plan revision, and high-risk unsupported-claim blocking.

## Implementation Details

- Backend endpoints:
  - `GET /api/articles/{article_id}/evidence`
  - `PATCH /api/articles/{article_id}/evidence/{evidence_id}`
  - Claim review operations under article evidence routes.
- Evidence matrix maps:
  - Plan sections.
  - Claims.
  - Evidence items.
  - Source quality score.
  - Support status.
  - Risk level.
- If research cannot find enough acceptable evidence for the approved plan:
  - Move workflow to `PLAN_REVISION_REQUIRED`.
  - Do not allow drafting.
  - Show missing evidence reasons to Editor.
- High-risk unsupported claims:
  - Are visible in review screens.
  - Block final approval until resolved.
- Editor can approve/reject evidence and add/remove evidence manually.

## Public Interface

- Editor views evidence by section and claim.
- Editor can filter unsupported claims.
- Workflow refuses to draft if evidence is structurally insufficient.

## Acceptance Criteria

- [x] TDD pre-requirement: before implementation, write one failing behavior test showing insufficient evidence returns the article to `PLAN_REVISION_REQUIRED`; proceed one claim/evidence behavior at a time and record evidence in `Result`.
- [x] Every factual claim is mapped to at least one evidence item or marked unsupported.
- [x] Unsupported claims are visible by section.
- [x] High-risk unsupported claims block final approval.
- [x] Insufficient acceptable evidence blocks draft production and triggers plan revision.
- [x] Editor can approve, reject, add, and remove evidence.
- [x] Evidence UI supports section and unsupported-claim filters.
- [x] Evidence item retains URL, title, source type, summary, quality score, retrieval timestamp, and manifest reference.

## Verification

- Run evidence matrix API tests.
- Run frontend evidence UI tests.
- Run a smoke flow with both sufficient and insufficient fake research fixtures.

## Result

- Status: Accepted.
- TDD plan: Added `apps/backend/tests/integration/test_evidence_matrix_public_api.py` first, with the primary failing behavior around insufficient evidence forcing `PLAN_REVISION_REQUIRED` and blocking draft/final approval; then extended coverage for sufficient evidence flow and manual evidence add/remove operations.
- Red evidence: Before fixes, the evidence matrix behavior test failed with empty `evidence`/`claims` because `_build_matrix` was not fully applied in runtime flow (`test_sufficient_evidence_maps_claims_and_allows_draft` and insufficient scenario both failed).
- Green evidence: Implemented evidence matrix generation from research manifests, unsupported-claim gating, draft/final approval blockers, manual evidence CRUD operations (`POST/PATCH/DELETE` under article evidence routes), claim link updates after evidence removal, and FSD evidence UI with unsupported-only + section filters.
- Refactor notes: Added `EvidenceCreateRequest` contract and shared type generation; consolidated evidence update flows in `apps/backend/src/application/evidence.py`; ensured article detail response surfaces evidence and claims; updated frontend API client and evidence panel to support add/remove alongside approve/reject.
- Verification output: `PYTHONPATH=/private/tmp/pupline-backend-deps python3 -m unittest apps/backend/tests/integration/test_evidence_matrix_public_api.py apps/backend/tests/contracts/test_generated_contract_artifacts.py` passed. `node apps/frontend/tests/evidence_matrix.model.test.mjs` passed. `pnpm --filter @pipeline/frontend typecheck` passed. `bash tests/smoke/evidence-flow.sh` passed with Docker Compose after Docker socket escalation.