feat: add custom trigger key support with any-key recording

Allow users to configure any keyboard key (modifier or regular) as the
push-to-talk trigger, replacing the fixed Fn-only approach. Adds a
"record key" button in Settings that captures the next keypress as the
new trigger key. Default remains Fn.

- Rewrite KeyMonitor with TriggerKeyConfig struct (Codable, any key)
- Add key recording mode with captureKeyConfig() and UCKeyTranslate
- Replace fixed Picker with "press any key to record" UI in Settings
- Dynamic menu bar text showing current trigger key name
- Notification-based coordination between Settings UI and KeyMonitor

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ZhaoChaoqun

Sources/KeyMonitor.swift

@@ -5,16 +5,92 @@ import os
 
 private let logger = Logger(subsystem: "com.typeless.app", category: "KeyMonitor")
 
-/// 监听全局 Fn 键按下/松开
+/// 触发键配置，支持修饰键和普通键
+struct TriggerKeyConfig: Codable, Equatable {
+    /// 事件类型：flagsChanged (修饰键) 或 keyDown/keyUp (普通键)
+    let isModifierKey: Bool
+    /// 按键的 keyCode
+    let keyCode: Int64
+    /// 修饰键的 flag 掩码（仅修饰键有效，如 .maskSecondaryFn = 0x800000）
+    let flagMask: UInt64
+    /// 用户可读的按键名称
+    let displayName: String
+
+    /// 默认触发键：Fn
+    static let defaultFn = TriggerKeyConfig(
+        isModifierKey: true,
+        keyCode: -1,  // Fn 不使用 keyCode，而是检查 flagMask
+        flagMask: CGEventFlags.maskSecondaryFn.rawValue,
+        displayName: "Fn"
+    )
+
+    /// 从 UserDefaults 读取，默认 Fn
+    static var current: TriggerKeyConfig {
+        guard let data = UserDefaults.standard.data(forKey: "triggerKeyConfig"),
+              let config = try? JSONDecoder().decode(TriggerKeyConfig.self, from: data) else {
+            return .defaultFn
+        }
+        return config
+    }
+
+    /// 保存到 UserDefaults
+    func save() {
+        if let data = try? JSONEncoder().encode(self) {
+            UserDefaults.standard.set(data, forKey: "triggerKeyConfig")
+        }
+    }
+
+    /// 检查事件是否匹配此触发键
+    func matches(type: CGEventType, event: CGEvent) -> Bool? {
+        if isModifierKey {
+            guard type == .flagsChanged else { return nil }
+            if keyCode >= 0 {
+                // 区分左右修饰键（如 Right Command keyCode=54）
+                let eventKeyCode = event.getIntegerValueField(.keyboardEventKeycode)
+                guard eventKeyCode == keyCode else { return nil }
+            }
+            return event.flags.rawValue & flagMask != 0
+        } else {
+            let eventKeyCode = event.getIntegerValueField(.keyboardEventKeycode)
+            guard eventKeyCode == keyCode else { return nil }
+            if type == .keyDown { return true }
+            if type == .keyUp { return false }
+            return nil
+        }
+    }
+}
+
+// MARK: - Notification for trigger key changes
+
+extension Notification.Name {
+    static let triggerKeyChanged = Notification.Name("triggerKeyChanged")
+    /// Settings UI 请求进入按键录制模式
+    static let triggerKeyRecordingRequested = Notification.Name("triggerKeyRecordingRequested")
+    /// Settings UI 取消按键录制
+    static let triggerKeyRecordingCancelled = Notification.Name("triggerKeyRecordingCancelled")
+    /// KeyMonitor 录制到新按键后通知 Settings UI（object 为 TriggerKeyConfig）
+    static let triggerKeyRecorded = Notification.Name("triggerKeyRecorded")
+}
+
+/// 监听全局触发键按下/松开（支持任意按键）
 class KeyMonitor {
     var onKeyDown: (() -> Void)?
     var onKeyUp: (() -> Void)?
 
+    /// 按键录制模式的回调：录制到一个按键后回调
+    var onKeyRecorded: ((TriggerKeyConfig) -> Void)?
+
     private var eventTap: CFMachPort?
     private var runLoopSource: CFRunLoopSource?
-    private var isFnPressed = false
+    private var isTriggerPressed = false
     private var permissionCheckTimer: Timer?
 
+    /// 当前配置的触发键
+    private var triggerConfig: TriggerKeyConfig = .current
+
+    /// 是否处于按键录制模式
+    var isRecordingKey = false
+
     func startMonitoring() {
         // 单元测试环境下跳过监听（避免弹出辅助功能权限窗口）
         if ProcessInfo.processInfo.environment["XCTestConfigurationFilePath"] != nil {
@@ -42,9 +118,15 @@ class KeyMonitor {
             return
         }
 
-        // 监听 flagsChanged 事件（修饰键变化）
-        let eventMask: CGEventMask = (1 << CGEventType.flagsChanged.rawValue)
-        logger.debug("事件掩码: \(eventMask, privacy: .public)")
+        // 监听所有需要的事件类型（修饰键 + 普通键）
+        let eventMask: CGEventMask =
+            (1 << CGEventType.flagsChanged.rawValue) |
+            (1 << CGEventType.keyDown.rawValue) |
+            (1 << CGEventType.keyUp.rawValue)
+
+        // 刷新触发键配置
+        triggerConfig = .current
+        logger.info("触发键: \(self.triggerConfig.displayName, privacy: .public)")
 
         guard let tap = CGEvent.tapCreate(
             tap: .cgSessionEventTap,
@@ -71,8 +153,15 @@ class KeyMonitor {
         CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, .commonModes)
         CGEvent.tapEnable(tap: tap, enable: true)
 
-        logger.info("Fn 键监听已启动，按下 Fn 键测试")
-        logger.debug("提示：如果你使用外接键盘，Fn 键检测可能不同")
+        logger.info("触发键监听已启动（\(self.triggerConfig.displayName, privacy: .public)）")
+    }
+
+    /// 切换触发键后重新启动监听
+    func restartWithNewTriggerKey() {
+        stopMonitoring()
+        isTriggerPressed = false
+        triggerConfig = .current
+        startMonitoring()
     }
 
     private func handleEvent(proxy: CGEventTapProxy, type: CGEventType, event: CGEvent) -> Unmanaged<CGEvent>? {
@@ -85,31 +174,163 @@ class KeyMonitor {
             return Unmanaged.passRetained(event)
         }
 
+        // 按键录制模式：捕获下一个按键作为新触发键
+        if isRecordingKey {
+            if let config = captureKeyConfig(type: type, event: event) {
+                isRecordingKey = false
+                logger.info("录制到新触发键: \(config.displayName, privacy: .public) (keyCode=\(config.keyCode))")
+                DispatchQueue.main.async {
+                    self.onKeyRecorded?(config)
+                }
+                return nil  // 吞掉录制的按键事件
+            }
+            return Unmanaged.passRetained(event)
+        }
+
+        // 正常触发键检测模式
+        if let pressed = triggerConfig.matches(type: type, event: event) {
+            handleTriggerState(pressed: pressed)
+            // 非修饰键需要吞掉事件，防止触发系统默认行为
+            if !triggerConfig.isModifierKey {
+                return nil
+            }
+        }
+
+        return Unmanaged.passRetained(event)
+    }
+
+    /// 从事件中捕获按键配置（用于录制模式）
+    private func captureKeyConfig(type: CGEventType, event: CGEvent) -> TriggerKeyConfig? {
+        let keyCode = event.getIntegerValueField(.keyboardEventKeycode)
+
         if type == .flagsChanged {
+            // 修饰键：检测哪个 flag 变化了
             let flags = event.flags
 
-            // 检测 Fn 键状态
-            // Fn 键通过 secondaryFn 标志检测
-            let fnPressed = flags.contains(.maskSecondaryFn)
+            if flags.contains(.maskSecondaryFn) {
+                return TriggerKeyConfig(isModifierKey: true, keyCode: -1,
+                                        flagMask: CGEventFlags.maskSecondaryFn.rawValue, displayName: "Fn")
+            }
+            if flags.contains(.maskCommand) {
+                let name = keyCode == 54 ? "Right Command ⌘" : "Left Command ⌘"
+                return TriggerKeyConfig(isModifierKey: true, keyCode: keyCode,
+                                        flagMask: CGEventFlags.maskCommand.rawValue, displayName: name)
+            }
+            if flags.contains(.maskAlternate) {
+                let name = keyCode == 61 ? "Right Option ⌥" : "Left Option ⌥"
+                return TriggerKeyConfig(isModifierKey: true, keyCode: keyCode,
+                                        flagMask: CGEventFlags.maskAlternate.rawValue, displayName: name)
+            }
+            if flags.contains(.maskControl) {
+                let name = keyCode == 62 ? "Right Control ⌃" : "Left Control ⌃"
+                return TriggerKeyConfig(isModifierKey: true, keyCode: keyCode,
+                                        flagMask: CGEventFlags.maskControl.rawValue, displayName: name)
+            }
+            if flags.contains(.maskShift) {
+                let name = keyCode == 60 ? "Right Shift ⇧" : "Left Shift ⇧"
+                return TriggerKeyConfig(isModifierKey: true, keyCode: keyCode,
+                                        flagMask: CGEventFlags.maskShift.rawValue, displayName: name)
+            }
+            return nil
+        }
 
-            if fnPressed && !isFnPressed {
-                // Fn 键按下
-                isFnPressed = true
-                logger.info("Fn 键按下，触发录音")
-                DispatchQueue.main.async {
-                    self.onKeyDown?()
-                }
-            } else if !fnPressed && isFnPressed {
-                // Fn 键松开
-                isFnPressed = false
-                logger.info("Fn 键松开，停止录音")
-                DispatchQueue.main.async {
-                    self.onKeyUp?()
-                }
+        if type == .keyDown {
+            // 普通键：用 keyCode 标识
+            let name = keyCodeDisplayName(keyCode)
+            return TriggerKeyConfig(isModifierKey: false, keyCode: keyCode,
+                                    flagMask: 0, displayName: name)
+        }
+
+        return nil
+    }
+
+    /// 将 keyCode 转为人类可读名称
+    private func keyCodeDisplayName(_ keyCode: Int64) -> String {
+        // 常见特殊键
+        switch keyCode {
+        case 110: return "App / Menu"
+        case 53: return "Escape"
+        case 36: return "Return"
+        case 48: return "Tab"
+        case 49: return "Space"
+        case 51: return "Delete"
+        case 117: return "Forward Delete"
+        case 114: return "Insert"
+        case 115: return "Home"
+        case 119: return "End"
+        case 116: return "Page Up"
+        case 121: return "Page Down"
+        case 123: return "←"
+        case 124: return "→"
+        case 125: return "↓"
+        case 126: return "↑"
+        case 122: return "F1"
+        case 120: return "F2"
+        case 99: return "F3"
+        case 118: return "F4"
+        case 96: return "F5"
+        case 97: return "F6"
+        case 98: return "F7"
+        case 100: return "F8"
+        case 101: return "F9"
+        case 109: return "F10"
+        case 103: return "F11"
+        case 111: return "F12"
+        case 105: return "F13"
+        case 107: return "F14"
+        case 113: return "F15"
+        default:
+            // 尝试用 Carbon 获取字符名称
+            if let char = keyCodeToCharacter(keyCode) {
+                return String(char).uppercased()
             }
+            return "Key \(keyCode)"
         }
+    }
 
-        return Unmanaged.passRetained(event)
+    /// 将 keyCode 转为字符（用于字母/数字键）
+    private func keyCodeToCharacter(_ keyCode: Int64) -> Character? {
+        let source = TISCopyCurrentKeyboardLayoutInputSource()?.takeRetainedValue()
+        guard let layoutData = TISGetInputSourceProperty(source!, kTISPropertyUnicodeKeyLayoutData) else { return nil }
+        let layout = unsafeBitCast(layoutData, to: CFData.self)
+        let keyboardLayout = unsafeBitCast(CFDataGetBytePtr(layout), to: UnsafePointer<UCKeyboardLayout>.self)
+
+        var deadKeyState: UInt32 = 0
+        var chars = [UniChar](repeating: 0, count: 4)
+        var length: Int = 0
+
+        let status = UCKeyTranslate(
+            keyboardLayout,
+            UInt16(keyCode),
+            UInt16(kUCKeyActionDown),
+            0, // no modifiers
+            UInt32(LMGetKbdType()),
+            UInt32(kUCKeyTranslateNoDeadKeysMask),
+            &deadKeyState,
+            chars.count,
+            &length,
+            &chars
+        )
+
+        guard status == noErr, length > 0 else { return nil }
+        return Character(UnicodeScalar(chars[0])!)
+    }
+
+    /// 统一处理触发键状态变化
+    private func handleTriggerState(pressed: Bool) {
+        if pressed && !isTriggerPressed {
+            isTriggerPressed = true
+            logger.info("\(self.triggerConfig.displayName, privacy: .public) 按下，触发录音")
+            DispatchQueue.main.async {
+                self.onKeyDown?()
+            }
+        } else if !pressed && isTriggerPressed {
+            isTriggerPressed = false
+            logger.info("\(self.triggerConfig.displayName, privacy: .public) 松开，停止录音")
+            DispatchQueue.main.async {
+                self.onKeyUp?()
+            }
+        }
     }
 
     func stopMonitoring() {

Sources/SettingsGeneralView.swift

@@ -4,10 +4,56 @@ import SwiftUI
 struct SettingsGeneralView: View {
     @AppStorage("analyticsEnabled") private var analyticsEnabled = true
 
+    /// 当前触发键的显示名称（从 TriggerKeyConfig 读取）
+    @State private var triggerKeyName: String = TriggerKeyConfig.current.displayName
+    /// 是否处于按键录制状态
+    @State private var isRecording = false
+
     var body: some View {
-        Section("快捷键") {
-            Text("长按 Fn 键开始录音")
-                .foregroundColor(.secondary)
+        Section {
+            HStack {
+                Text("触发键")
+                Spacer()
+                if isRecording {
+                    Text("请按下任意键...")
+                        .foregroundStyle(.secondary)
+                        .italic()
+                } else {
+                    Text(triggerKeyName)
+                        .foregroundStyle(.secondary)
+                }
+                Button(isRecording ? "取消" : "录制按键") {
+                    if isRecording {
+                        // 取消录制
+                        isRecording = false
+                        NotificationCenter.default.post(
+                            name: .triggerKeyRecordingCancelled, object: nil)
+                    } else {
+                        // 开始录制
+                        isRecording = true
+                        NotificationCenter.default.post(
+                            name: .triggerKeyRecordingRequested, object: nil)
+                    }
+                }
+                .buttonStyle(.bordered)
+            }
+            if triggerKeyName != TriggerKeyConfig.defaultFn.displayName {
+                Button("恢复默认 (Fn)") {
+                    TriggerKeyConfig.defaultFn.save()
+                    triggerKeyName = TriggerKeyConfig.defaultFn.displayName
+                    NotificationCenter.default.post(name: .triggerKeyChanged, object: nil)
+                }
+            }
+        } header: {
+            Text("快捷键")
+        } footer: {
+            Text("长按所选按键开始录音，松开结束。外接机械键盘的 Fn 键通常无法被系统检测，建议录制其他按键。")
+        }
+        .onReceive(NotificationCenter.default.publisher(for: .triggerKeyRecorded)) { notification in
+            if let config = notification.object as? TriggerKeyConfig {
+                triggerKeyName = config.displayName
+                isRecording = false
+            }
         }
 
         Section("关于") {