# Step 1: property-base-interface

## Read First

Read these files before editing:

- `/AGENTS.md`
- `/docs/AGENT_RULES.md`
- `/docs/implementation-plans/property-model-foundation-implementation-plan.md`
- `/include/fesa/core/ModelTypes.hpp`
- `/include/fesa/property/ShellProperty.hpp`
- `/tests/property/shell_property_test.cpp`
- `/CMakeLists.txt`

## Task

Add the runtime property base interface.

Required API:

- File: `/include/fesa/property/Property.hpp`
- Namespace: `fesa::property`
- `enum class PropertyKind { Shell };`
- `class Property`
  - virtual destructor;
  - `virtual PropertyId id() const noexcept = 0;`
  - `virtual PropertyKind kind() const noexcept = 0;`

Rules:

- Use `fesa::core::PropertyId`.
- Do not add section stiffness or material behavior.
- Keep this header independent from HDF5, MKL, TBB, and parser headers.

## Tests To Write First

- Add `/tests/property/property_base_test.cpp`.
- Test that a small derived class can be used through `const Property&`.
- Test virtual deletion through `std::unique_ptr<Property>`.

## Acceptance Criteria

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

## Verification Notes

1. Run targeted CTest before implementation and confirm the expected compile failure.
2. Keep all code C++17/MSVC-compatible.
3. Update `phases/property-model-foundation/index.json` for this step result.