# Step 3: domain-property-ownership

## 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/Domain.hpp`
- `/src/core/Domain.cpp`
- `/include/fesa/property/Property.hpp`
- `/include/fesa/property/ShellProperty.hpp`
- `/tests/core/domain_storage_test.cpp`
- `/tests/core/domain_model_object_test.cpp`

## Task

Make `Domain` own runtime property objects through the `Property` base class.

Required API shape:

- `void Domain::addProperty(std::unique_ptr<fesa::property::Property> property);`
- `const fesa::property::Property* Domain::findProperty(PropertyId id) const noexcept;`
- `const fesa::property::Property& Domain::property(PropertyId id) const;`
- `std::size_t Domain::propertyCount() const noexcept;`

Compatibility helpers may remain if useful:

- `addShellProperty(std::unique_ptr<fesa::property::ShellProperty>)`
- `findShellProperty(PropertyId)`
- `shellProperty(PropertyId)`
- `shellPropertyCount()`

Rules:

- Property storage must be `std::unique_ptr<Property>`.
- Reject null property pointers.
- Reject duplicate property ids.
- For `ShellProperty`, reject missing material id.
- `Domain::addElement` must validate `Element::propertyId()` using runtime property storage.

## Tests To Write First

- Rewrite relevant property assertions in `/tests/core/domain_storage_test.cpp` to use runtime property ownership.
- Add a test that `const Domain::property(id)` returns `const Property&`.
- Preserve direct `ShellProperty` lookup for now if compatibility helpers remain.

## Acceptance Criteria

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

## Verification Notes

1. Run targeted CTest before production edits and confirm failure.
2. Do not add solver vectors, equation ids, or integration-point state to `Domain`.
3. Update `phases/property-model-foundation/index.json` for this step result.