add --hotkey option to pick the push-to-talk key (fn or right-option)

Sources/parrot/Input/HotkeyMonitor.swift

@@ -12,14 +12,18 @@ final class HotkeyMonitor {
 
     /// Mask of the modifier we treat as the hotkey. Fn = `.maskSecondaryFn`.
     private let mask: CGEventFlags
+    /// When set, only flagsChanged events with this keycode are considered,
+    /// so left/right variants of a modifier can be told apart.
+    private let keycode: Int64?
     private let debug: Bool
     private var onEvent: ((Event) -> Void)?
     private var tap: CFMachPort?
     private var runLoopSource: CFRunLoopSource?
     private var isPressed = false
 
-    init(mask: CGEventFlags = .maskSecondaryFn, debug: Bool = false) {
+    init(mask: CGEventFlags = .maskSecondaryFn, keycode: Int64? = nil, debug: Bool = false) {
         self.mask = mask
+        self.keycode = keycode
         self.debug = debug
     }
 
@@ -87,6 +91,7 @@ final class HotkeyMonitor {
                 ))
         }
         guard type == .flagsChanged else { return }
+        if let keycode, event.getIntegerValueField(.keyboardEventKeycode) != keycode { return }
         let pressed = event.flags.contains(mask)
         guard pressed != isPressed else { return }
         isPressed = pressed

Sources/parrot/Parrot.swift

@@ -34,6 +34,9 @@ struct Run: ParsableCommand {
     @Option(name: .long, help: "Model id to use. Defaults to the recommended model.")
     var model: String?
 
+    @Option(name: .long, help: "Push-to-talk key: fn (default) or right-option.")
+    var hotkey: String = "fn"
+
     func run() throws {
         if !skipDoctor {
             let checks = DoctorReport.run()
@@ -81,7 +84,16 @@ struct Run: ParsableCommand {
         let app = NSApplication.shared
         app.setActivationPolicy(.accessory)
 
-        let monitor = HotkeyMonitor(debug: debugHotkey)
+        let monitor: HotkeyMonitor
+        switch hotkey {
+        case "fn":
+            monitor = HotkeyMonitor(debug: debugHotkey)
+        case "right-option":
+            monitor = HotkeyMonitor(mask: .maskAlternate, keycode: 61, debug: debugHotkey)
+        default:
+            FileHandle.standardError.write(Data("unknown hotkey: \(hotkey) (use fn or right-option)\n".utf8))
+            throw ExitCode(1)
+        }
         let capture = AudioCapture()
         let dumpWav = self.dumpWav
         let overlay: RecordingOverlay? = noOverlay ? nil : MainActor.assumeIsolated { RecordingOverlay() }
@@ -169,7 +181,7 @@ struct Run: ParsableCommand {
         sigint.resume()
         signal(SIGINT, SIG_IGN)
 
-        FileHandle.standardError.write(Data("listening on fn hold · model: \(chosenModel.id) · ^C to quit\n".utf8))
+        FileHandle.standardError.write(Data("listening on \(hotkey) hold · model: \(chosenModel.id) · ^C to quit\n".utf8))
         app.run()
     }
 }