# Step 3: formula-reference-links

## Read First
- /AGENTS.md
- /PLAN.md
- /PROGRESS.md
- /docs/HARNESS.md
- /docs/IMPLEMENTATION_PLAN.md
- /docs/CONVERSION_POLICY.md
- /phases/3-formula-pipeline/step2.md

## Task
Preserve formula numbering and body references as internal Markdown link targets when confidence is sufficient.

Support common English and Korean reference patterns such as `Eq. (3)` and `식 (5)`.

## Sprint Contract
- Done means: formula anchors and reference rewrites are modeled and tested independently from final Markdown rendering.
- Hard thresholds: low-confidence matches remain plain text; duplicate formula numbers do not create unstable anchors; references never point to missing anchors.
- Files owned: `src/pdftomd/formulas.py`, reference model/tests, `PROGRESS.md`, phase index.
- Dependencies: Steps 0 through 2.

## Acceptance Criteria
```powershell
python scripts\validate_workspace.py
.\venv\python.exe -m pytest tests
```

## Verification
1. Run the acceptance commands.
2. Confirm duplicate and missing reference cases are tested.
3. Update `PROGRESS.md` and this phase index.

## Do Not
- Do not rewrite ambiguous references.
- Do not render final Markdown chunks.
- Do not remove the original formula number text.