# Step 1: nougat-command-adapter

## Read First
- /AGENTS.md
- /PLAN.md
- /PROGRESS.md
- /docs/HARNESS.md
- /docs/IMPLEMENTATION_PLAN.md
- /docs/TOOLCHAIN.md
- /docs/CONVERSION_POLICY.md
- /phases/3-formula-pipeline/step0.md

## Task
Implement the Nougat formula-only adapter boundary.

The adapter should accept formula candidates and return LaTeX candidates or structured failure results. It should support a configured Nougat command path and be mockable in unit tests.

## Sprint Contract
- Done means: Nougat execution is isolated behind a testable command adapter and never becomes the primary document parser.
- Hard thresholds: failures preserve Marker fallback text; tests do not require GPU/model execution by default; command path handling works on Windows.
- Files owned: `src/pdftomd/formulas.py`, optional `src/pdftomd/nougat_adapter.py`, tests, `PROGRESS.md`, phase index.
- Dependencies: Step 0 formula candidates and Phase 1 options.

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

## Verification
1. Run the acceptance commands.
2. Confirm `.\venv\Scripts\nougat.exe --help` remains documented as an environment check, not a unit-test requirement.
3. Update `PROGRESS.md` and this phase index.

## Do Not
- Do not parse whole PDFs with Nougat.
- Do not require model downloads for normal unit tests.
- Do not discard Marker source text on failure.