# Sprint Contract: MITC4 Patch Benchmark Tests

## Objective
Add element-level and small-mesh MITC4 patch and benchmark tests before integrating stored Abaqus references.

## Required Reading
- /AGENTS.md
- /docs/MITC4_FORMULATION.md
- /docs/VERIFICATION_PLAN.md
- /docs/NUMERICAL_CONVENTIONS.md

## Scope
- Add constant membrane, pure bending, pure shear, pure twist, rigid-body, and drilling sensitivity tests.
- Add a thin cantilever or plate strip test to expose shear locking.
- Add benchmark scaffolding for Scordelis-Lo after flat tests pass.

## Allowed Files
- `tests/`
- `include/`
- `src/` only for minimal fixes required by tests
- `docs/VERIFICATION_PLAN.md` only for clarifying benchmark notes
- `PLAN.md`
- `PROGRESS.md`

## Explicit Non-Goals
- Do not require Abaqus execution.
- Do not add pressure loads for Scordelis-Lo in Phase 1.
- Do not hide failing element behavior by loosening tolerances without rationale.

## Tests To Write First
- The patch and benchmark tests are the sprint output; write them before any fixes.
- Include at least one negative or sensitivity test for drilling scale effects.

## Reference Artifacts
- Local analytic or hand-check benchmark data only.
- Stored Abaqus CSV regression is reserved for step 14.

## Acceptance Commands
```bash
python scripts/validate_workspace.py
```

## Evaluator Checklist
- Tests cover locking-sensitive behavior, not only shape functions.
- Tolerances are scale-aware and documented.
- Any implementation fixes remain minimal and within MITC4 scope.

## Handoff Requirements
- Record benchmark coverage and remaining gaps in `PROGRESS.md` and `PLAN.md`.

## Do Not
- Do not implement new load types to force a benchmark into Phase 1.