# Sprint Contract: Results Comparator Foundation

## Objective
Rebuild or verify the minimum Phase 1 results model and Abaqus displacement CSV comparator before using stored reference regressions.

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

## Scope
- Store minimum result model data for nodes, elements, `U`, and `RF`.
- Preserve step/frame/field structure even if HDF5 writing is deferred.
- Load Abaqus `*_displacements.csv` by node id and component label.
- Compare using absolute and relative tolerances.

## Allowed Files
- `include/`
- `src/`
- `tests/`
- `docs/RESULTS_SCHEMA.md` only for clarifying schema text
- `docs/VERIFICATION_PLAN.md` only for clarifying tolerance/reference text
- `PLAN.md`
- `PROGRESS.md`

## Explicit Non-Goals
- Do not make `S`, `E`, or `SF` mandatory.
- Do not require Abaqus execution.
- Do not rely on CSV row order.

## Tests To Write First
- `U` and `RF` field component labels and basis tests.
- CSV required-header tests.
- Duplicate/missing/non-numeric node row tests.
- Node-id-based comparison tests with absolute and relative tolerance paths.
- Result frame metadata tests for Phase 1 linear static frame 0.

## Reference Artifacts
- `references/quad_02_displacements.csv`
- `references/quad_01_displacements.csv`

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

## Evaluator Checklist
- Result component order matches docs.
- Comparator maps Abaqus columns to FESA `U` labels exactly.
- `RF` exists as a result field even if Abaqus RF CSV is unavailable.

## Handoff Requirements
- Record comparator readiness and remaining RF artifact decision in `PROGRESS.md` and `PLAN.md`.

## Do Not
- Do not add undocumented CSV formats.