# Step 7: boundary-base-interface

## Read First

Read these files before editing:

- `/AGENTS.md`
- `/docs/AGENT_RULES.md`
- `/docs/ARCHITECTURE.md`
- `/docs/implementation-plans/analysis-model-objects-implementation-plan.md`
- `/include/fesa/core/BoundaryCondition.hpp`

## Task

Add boundary condition model base and single-point constraint object.

Allowed files:

- Create `/include/fesa/boundary/BoundaryCondition.hpp`
- Create `/include/fesa/boundary/SinglePointConstraint.hpp`
- Create `/src/boundary/SinglePointConstraint.cpp`
- Create `/tests/boundary/boundary_base_test.cpp`
- Modify `/CMakeLists.txt`

Required behavior:

- `BoundaryCondition` has virtual destructor and a boundary kind enum.
- `SinglePointConstraint` derives from `BoundaryCondition`.
- Stores node id, DOF, prescribed value.
- No matrix elimination or reaction recovery in this phase.

## Tests To Write First

Write `/tests/boundary/boundary_base_test.cpp` before production changes:

- Access `SinglePointConstraint` through `const BoundaryCondition&`.
- Verify kind, node id, DOF, value.
- Verify deletion through `std::unique_ptr<BoundaryCondition>`.

Run targeted build and confirm RED.

## Acceptance Criteria

Run:

```powershell
python scripts/validate_workspace.py
ctest --test-dir build/msvc-debug --output-on-failure -C Debug -R model-object
```

Update step 7 status.

## Do Not

- Do not apply constraints to matrices or compute reactions.