# Step 10: mitc4-formulation-closure

## Sprint Contract

### Objective
Close the MITC4 formulation decisions required before element implementation: transverse shear tying, local basis, integration ordering, drilling stiffness default, and Phase 1 output scope.

### Required Reading
- /AGENTS.md
- /PROGRESS.md
- /PLAN.md
- /docs/README.md
- /docs/HARNESS_ENGINEERING.md
- /docs/PRD.md
- /docs/NUMERICAL_CONVENTIONS.md
- /docs/RESULTS_SCHEMA.md
- /docs/MITC4_FORMULATION.md
- /docs/VERIFICATION_PLAN.md

### Scope
- Update `docs/MITC4_FORMULATION.md` with the exact baseline formulas and implementation checklist needed for coding.
- Resolve or explicitly defer R-004, R-005, R-006, and R-007.
- Record literature/source basis and benchmark expectations without requiring local Abaqus execution.
- Update ADR or PLAN only when a durable design decision changes.

### Allowed Files
- `docs/MITC4_FORMULATION.md`
- `docs/RESULTS_SCHEMA.md`
- `docs/VERIFICATION_PLAN.md`
- `docs/ADR.md`
- `PLAN.md`
- `PROGRESS.md`
- `phases/1-linear-static-mitc4/index.json`

### Explicit Non-Goals
- Do not implement C++ MITC4 code in this step.
- Do not invent formulas from memory without documenting the source or derivation.
- Do not expand Phase 1 outputs beyond resolved R-007.

### Tests To Write First
- No C++ tests are required unless executable formulation checks already exist.
- Add documentation checklist items or review notes that can be evaluated before Step 11.

### Reference Artifacts
- None required. Existing `references/quad_01*` may inform future benchmark planning but is not a Phase 1 MITC4 acceptance case.

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

### Evaluator Checklist
- Transverse shear tying equations are explicit enough to implement.
- Local shell basis construction is explicit for flat and non-flat quads.
- Drilling stiffness default scale and parameter name are finalized.
- Integration ordering and output scope are finalized or explicitly deferred with downstream blockers.
- Step 11 remains blocked if any required formulation item is unresolved.

### Handoff Requirements
- Record closed decisions and remaining risks in `PROGRESS.md`.
- Remove or update resolved readiness tasks in `PLAN.md`.
- Update the matching phase index entry: use `completed` with a one-line `summary`, or `blocked` with `blocked_reason`, or `error` with `error_message`.

## Verification
1. Run the acceptance command.
2. Review docs for implementable formulas and unresolved placeholders.

## Do Not
- Do not let implementation begin on undocumented MITC4 formulas.