# Sprint Contract: Dof Manager Reaction Foundation

## Objective
Rebuild or verify the six-DOF `DofManager`, constrained/free mapping, equation numbering, sparse-pattern inputs, and full-vector reconstruction needed for reaction recovery.

## Required Reading
- /AGENTS.md
- /docs/ARCHITECTURE.md
- /docs/ADR.md
- /docs/NUMERICAL_CONVENTIONS.md
- /docs/RESULTS_SCHEMA.md

## Scope
- Manage active six-DOF shell nodes.
- Apply fixed constraints by constrained DOF elimination.
- Own equation numbering and sparse connectivity inputs.
- Reconstruct full vectors in original global DOF order.
- Provide data needed for `RF = K_full * U_full - F_full`.

## Allowed Files
- `include/`
- `src/`
- `tests/`
- `PLAN.md`
- `PROGRESS.md`

## Explicit Non-Goals
- Do not assemble MITC4 stiffness.
- Do not store equation ids in `Node` or `Element`.
- Do not compute `RF` from reduced vectors only.

## Tests To Write First
- DOF activation and Abaqus component order.
- Constrained/free partition tests.
- Equation numbering stability with noncontiguous node ids.
- Full/reduced vector reconstruction tests.
- Sparse-pattern connectivity input tests.
- Full-vector reaction formula unit test with a small known matrix.

## Reference Artifacts
- None.

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

## Evaluator Checklist
- `DofManager` owns all equation numbering.
- Full-space order is deterministic and matches `UX,UY,UZ,RX,RY,RZ`.
- Reaction foundation preserves constrained DOF information.

## Handoff Requirements
- Record DOF and reaction foundation status in `PROGRESS.md`.

## Do Not
- Do not bypass `DofManager` from elements or analysis code.