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# facet_appkit

The macOS backend for [facet](/docs/packages/facet). facet owns the description tree and all layout ([`flex_layout`](/docs/packages/flex_layout)). This package fills the backend seams: `Renderer`, scheduler, key reader, sender readers, and theme slots.

The public surface is `install()` (and `installed()` / `uninstall()`). There is no `render` and no `run(tree)`.

```cplus
import "facet_appkit/facet_appkit" as backend;
import "facet/runtime" as runtime;
import "stdlib/status" as status;

fn main() -> i32 {
    backend::install();
    var app: runtime::App = runtime::App::new("hello");
    app.screen("home", home_screen);
    return match app.run("home") {
        status::Status::Ok => 0,
        _other => 1,
    };
}
```

`install` is idempotent. It arms the mount renderer, the UI-thread assert, the run-loop observer that syncs dirty nodes, and the reactor pump so `spawn_ui` tasks resume. Agent serving is **not** installed here: call `facet/agent::enable()` before `app.run` if the app should serve.

Deps: `objc`, `appkit`, [`quartzcore`](/docs/packages/quartzcore) (`NSView.layer()` is a real `CALayer`), `flex_layout`, `facet`, `webkit` (for `web` / `hybrid_web`).

macOS only. The same facet tree is drawn on Linux by [`facet_gtk`](/docs/packages/facet_gtk). To drive a running AppKit app from an external agent, see the [agent surface](/docs/agent-surface).