# Nebula Windows

Shared C++ window-management service. Desktop, the future Bigscreen shell, and a future Nebula compositor backend should all talk to this library rather than to a compositor directly.

```text
Nebula QML
    ↓
WindowService
    ↓
generic WindowBackend
    ↓
Sway IPC          now
Nebula compositor later
```

QML must not run `swaymsg`. Sway-specific protocol, socket handling, and tree parsing stay in `backends/sway/`.

## Behaviour

- Connects to the compositor IPC socket from `SWAYSOCK`. The path is never hard-coded.
- If IPC is missing or fails, the shell keeps running and WindowService stays empty. A development warning is logged.
- Subscribes to `window`, `workspace`, and `output` events instead of polling.
- Exposes `WindowModel` (`QAbstractListModel`) and `WorkspaceModel`.
- Tracks the focused *normal application* window. Layer-shell chrome (desktop, top bar, launcher) is not treated as the active app.
- Resolves a user-facing name via `ApplicationService` when possible, then a small identifier humanizer (`footclient` → Foot, `org.mozilla.firefox` → Firefox).

QML module URI: `Nebula.Windows`.

## Operations

`focusWindow`, `closeWindow`, `maximizeWindow`, `restoreWindow`, `setWindowFloating`, plus `moveWindow` / `resizeWindow` / `snapWindow` / `switchWorkspace`.

`closeWindow` asks the compositor to close the client. It does not kill the process.

Maximise fills the current workspace usable area (below the Nebula exclusive zone) using compositor-relative sizing. Restore returns the previous floating geometry when WindowService saved it.

Minimise is implemented for the Sway backend using scratchpad semantics, but the UI must not mention scratchpad. The user-facing idea is only hide / show.

Snap edges (`SnapLeft`, `SnapRight`, `SnapMaximize`) are prepared for a later Snap Layouts UI.

See `shells/desktop/README.md` and `compositor/README.md` for session behaviour.