Desktop

macOS, Windows and Linux are compiled so the app runs in tauri dev — and nothing more. The desktop engines are not probed:

Engine	Platform	What it is
WebView2	Windows	Chromium, evergreen
WKWebView	macOS	Versioned with Safari, which updates independently of the OS on older releases
WebKitGTK	Linux	Versioned by the distribution

What happens

• At setup the guard logs one warning, through the log facade, naming the OS and the floor it would have applied: webview-guard: macos is not guarded (floor would be Chromium 111 / iOS 16.4); …
• The app's navigation is never refused: with no verdict, nothing blocks.
• Every call — status() and open_update(), from Rust or TypeScript — returns the typed unsupported error, rather than a status that would claim a verdict nobody computed:

{
  "kind": "unsupported",
  "platform": "macos",
  "capability": "status",
  "reason": "the webview guard checks the Android WebView provider and the iOS version; desktop engines are not probed"
}

A frontend shared between desktop and mobile should treat error.kind === "unsupported" as "nothing to show", not as a failure. See the error type.