# Skill: Multi-System Signaling (uLib ↔ Qt)

This skill manages the coexistence of `uLib::Object` signals and Qt's `Q_OBJECT` signaling system.

## Context
- **uLib Signals**: Used for domain logic and data changes (`uLib::Object::connect`).
- **Qt Signals**: Used for UI events, widgets, and application-level control flow (`QObject::connect`).

## Patterns

### 1. Bridging Logic
When a domain change needs to trigger a UI update, use a wrapper or a direct connection if the widget has access to the `uLib::Object`.
```cpp
// In a Qt Widget
uLib::Object::connect(domainObj, &Object::Updated, [this]() {
    this->update(); // Trigger Qt repaint
});
```

### 2. Selection Flow
Selection usually starts in the VTK Viewport (Qt) and flows to the domain context.
1. `QViewport` emits `prop3dSelected(Prop3D*)` (Qt signal).
2. `MainPanel` catches it and calls `contextPanel->selectObject(p->GetContent())`.
3. `ContextPanel` updates the tree view and property editors.

### 3. Connection Hygiene
- Use `uLib::Object::connect` for everything involving `uLib::Property` changes.
- Use Qt `connect` for button clicks, menu actions, and window events.
- Be careful with lambda captures; ensure the captured object is still alive or use weak pointers if necessary.

## Checklist
- [ ] Is the correct signaling system being used for the task?
- [ ] Are capture groups in lambdas safe?
- [ ] Does selection flow correctly between the 3D view and the tree view?