apps — which applications are running, and who has focus

apps is the observation tool you reach for before anything else: it answers “what is running?” and — with one query — “where do my keystrokes go right now?”. It never synthesizes input, so it is safe in every permission mode.

Computer::apps(&self, input: &ComputerApps) -> Result<AppsResult, String>
apps(metadata, ComputerApps) -> Result<AppsResult, String>          // free function

The two queries

1. target: "all" (default) — a point-in-time enumeration of running applications: name, PID (when the platform reports one), and which entry holds the system foreground. Enumeration order is the platform’s; the foreground flag is the stable fact.
2. target: "focused" — resolves the foreground application and the element inside it holding keyboard focus. This is the cheap ground truth the input tools previously guessed at: before typing, CHECK the focused element instead of assuming the last click landed. timeout_ms bounds the wait for a foreground app to exist at all.

Reading the result

The result is the untagged enum AppsResult — the variant follows the query:

• AppsResult::All(AppsOutput) — apps: Vec<AppInfo> + count;
• AppsResult::Focused(FocusedOutput) — the foreground app’s name/pid plus focused_element: Option<FocusedElement>. The Option matters: focus may sit on the window itself (no element), or the platform may not report element focus. Treat None as “keystrokes go to the window, not a named field”.

Edges

• Focus is a moment. Between the focused query and your next call the user may click elsewhere. For input that must land in a specific field, prefer a real click (control) over assuming focus persists.
• PIDs can be absent on some backends; never build logic that requires them. Scope other tools by name when possible.

See also

snapshot for the tree below the focused element · runnable example: cargo run --example computer-apps