feat: flow session reliability, keyboard UX, and audio pre-roll fix

Renew voice sessions while the host app stays foreground, auto-start flow from the keyboard with a Start action, and prevent leading audio loss via pre-roll buffering and faster signal polling.

OSGKeyboard/OSGKeyboardApp.swift

@@ -35,6 +35,9 @@ struct OSGKeyboardApp: App {
                 }
             }
             .environmentObject(flowManager)
+            .onAppear {
+                flowManager.setAppForeground(scenePhase == .active)
+            }
             .onOpenURL { url in
                 guard url.scheme == "osgkeyboard" else { return }
                 switch url.host {
@@ -56,6 +59,7 @@ struct OSGKeyboardApp: App {
                 if done { flowManager.autoStartIfNeeded() }
             }
             .onChange(of: scenePhase) { _, phase in
+                flowManager.setAppForeground(phase == .active)
                 guard phase == .active, AppGroup.isAvailable, config.hasCompletedOnboarding else { return }
                 if flowManager.isActive {
                     flowManager.extendSession()

OSGKeyboard/Services/FlowSessionManager.swift

@@ -35,6 +35,8 @@ final class FlowSessionManager: ObservableObject {
     private var asrTask: Task<Void, Never>?
     private var currentPartial = ""
     private var lastFinal = ""
+    /// True while the host app scene is `.active` — drives foreground renewal.
+    private var isAppForeground = false
 
     init() {
         Task { @MainActor [weak self] in
@@ -169,6 +171,24 @@ final class FlowSessionManager: ObservableObject {
         scheduleExpiry(after: duration)
     }
 
+    /// Called from `OSGKeyboardApp` when `scenePhase` changes.
+    func setAppForeground(_ foreground: Bool) {
+        isAppForeground = foreground
+        if foreground, isActive {
+            renewSessionIfNeededWhileForeground()
+        }
+    }
+
+    /// Extend the session before it expires while the host app stays in foreground.
+    private func renewSessionIfNeededWhileForeground() {
+        guard isActive, isAppForeground else { return }
+        guard let remaining = FlowSessionBridge.remainingSessionDuration() else { return }
+        let threshold = FlowSessionKeys.defaultSessionDuration * 0.25
+        guard remaining < threshold else { return }
+        extendSession()
+        debug("Flow session renewed in foreground (\(Int(threshold))s threshold)")
+    }
+
     // MARK: - Session start
 
     private func startSessionAsync(duration: TimeInterval) async {
@@ -217,7 +237,7 @@ final class FlowSessionManager: ObservableObject {
         pollingTask = Task { @MainActor [weak self] in
             while !Task.isCancelled {
                 self?.handleKeyboardSignal()
-                try? await Task.sleep(nanoseconds: 100_000_000)
+                try? await Task.sleep(nanoseconds: 50_000_000)
             }
         }
     }
@@ -424,6 +444,7 @@ final class FlowSessionManager: ObservableObject {
         heartbeatTask = Task { @MainActor [weak self] in
             while !Task.isCancelled {
                 FlowSessionBridge.writeHeartbeat()
+                self?.renewSessionIfNeededWhileForeground()
                 try? await Task.sleep(nanoseconds: 1_000_000_000)
                 guard self?.isActive == true else { break }
             }

OSGKeyboard/Views/HomeView.swift

@@ -42,8 +42,8 @@ struct HomeView: View {
 
                     engineStatusLine
                         .padding(.horizontal, Spacing.lg)
-                        .padding(.top, Spacing.md)
+                        .padding(.top, Spacing.xl)
-                        .padding(.bottom, Spacing.xs)
+                        .padding(.bottom, Spacing.sm)
                 }
                 .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .top)
             }
@@ -81,7 +81,7 @@ struct HomeView: View {
             Image("osglogo")
                 .resizable()
                 .scaledToFit()
-                .frame(width: 120, height: 34)
+                .frame(width: 144, height: 41)
                 .accessibilityHidden(true)
 
             statusCapsule
@@ -92,13 +92,6 @@ struct HomeView: View {
 
     private var statusCapsule: some View {
         HStack(spacing: Spacing.sm) {
-            Text(statusLine)
-                .font(TypeStyle.status)
-                .foregroundStyle(palette.textSecondary)
-                .fixedSize()
-
-            capsuleDivider
-
             flowCapsuleSegment
 
             if flowManager.isActive {
@@ -125,12 +118,6 @@ struct HomeView: View {
         .animation(Motion.soft, value: flowManager.isActive)
     }
 
-    private var capsuleDivider: some View {
-        Circle()
-            .fill(palette.dividerStrong)
-            .frame(width: 3, height: 3)
-    }
-
     @ViewBuilder
     private var flowCapsuleSegment: some View {
         HStack(spacing: Spacing.xs) {
@@ -165,12 +152,6 @@ struct HomeView: View {
             : palette.surface.opacity(0.88)
     }
 
-    private var statusLine: String {
-        config.isConfigured
-            ? NSLocalizedString("home.status.ready", comment: "")
-            : NSLocalizedString("home.status.setupIncomplete", comment: "")
-    }
-
     // MARK: - Flow extras (warnings / hint)
 
     @ViewBuilder

OSGKeyboard/Views/OnboardingView.swift

@@ -184,6 +184,11 @@ private struct OnboardingHeroIcon: View {
     }
 }
 
+private enum OnboardingLayoutMetrics {
+    /// Matches welcome page: logo → tagline, and subtitle → next block.
+    static let heroTextGap: CGFloat = Spacing.hero
+}
+
 // MARK: - Welcome
 
 private struct WelcomePage: View {
@@ -209,11 +214,11 @@ private struct WelcomePage: View {
             }
             .multilineTextAlignment(.center)
             .padding(.horizontal, Spacing.xl)
-            .padding(.top, Spacing.hero)
+            .padding(.top, OnboardingLayoutMetrics.heroTextGap)
 
             PrivacyFootnote()
                 .padding(.horizontal, Spacing.xl)
-                .padding(.top, Spacing.hero)
+                .padding(.top, OnboardingLayoutMetrics.heroTextGap)
 
             if let url = LegalLinks.privacyPolicyURL {
                 Link(destination: url) {
@@ -388,12 +393,12 @@ private struct PermissionPageLayout: View {
     var deniedHint: LocalizedStringKey? = nil
 
     var body: some View {
-        VStack(spacing: Spacing.xl) {
+        VStack(spacing: 0) {
             Spacer()
 
             OnboardingHeroIcon(systemName: icon, circleSize: 96, iconSize: 40)
 
-            VStack(spacing: Spacing.sm) {
+            VStack(spacing: Spacing.xs) {
                 Text(title)
                     .font(TypeStyle.title2)
                     .foregroundStyle(palette.textPrimary)
@@ -403,6 +408,7 @@ private struct PermissionPageLayout: View {
                     .multilineTextAlignment(.center)
                     .padding(.horizontal, Spacing.xl)
             }
+            .padding(.top, OnboardingLayoutMetrics.heroTextGap)
 
             HStack(spacing: 6) {
                 Circle().fill(statusColor).frame(width: 8, height: 8)
@@ -410,6 +416,7 @@ private struct PermissionPageLayout: View {
                     .font(TypeStyle.caption)
                     .foregroundStyle(palette.textSecondary)
             }
+            .padding(.top, OnboardingLayoutMetrics.heroTextGap)
 
             if let deniedHint {
                 Text(deniedHint)
@@ -417,6 +424,7 @@ private struct PermissionPageLayout: View {
                     .foregroundStyle(palette.warning)
                     .multilineTextAlignment(.center)
                     .padding(.horizontal, Spacing.xl)
+                    .padding(.top, Spacing.md)
             }
 
             VStack(spacing: Spacing.sm) {
@@ -436,6 +444,7 @@ private struct PermissionPageLayout: View {
                 }
             }
             .padding(.horizontal, Spacing.lg)
+            .padding(.top, Spacing.xl)
 
             Spacer()
         }
@@ -448,12 +457,12 @@ private struct EnableKeyboardPage: View {
     @Environment(\.themePalette) private var palette: ThemePalette
 
     var body: some View {
-        VStack(spacing: Spacing.xl) {
+        VStack(spacing: 0) {
             Spacer()
 
             OnboardingHeroIcon(systemName: "keyboard.fill", circleSize: 96, iconSize: 40)
 
-            VStack(spacing: Spacing.sm) {
+            VStack(spacing: Spacing.xs) {
                 Text("onboarding.enable.title")
                     .font(TypeStyle.title2)
                     .foregroundStyle(palette.textPrimary)
@@ -463,6 +472,7 @@ private struct EnableKeyboardPage: View {
                     .multilineTextAlignment(.center)
                     .padding(.horizontal, Spacing.lg)
             }
+            .padding(.top, OnboardingLayoutMetrics.heroTextGap)
 
             VStack(alignment: .leading, spacing: Spacing.lg) {
                 step(num: 1, text: NSLocalizedString("onboarding.enable.step1", comment: ""))
@@ -472,7 +482,7 @@ private struct EnableKeyboardPage: View {
             }
             .frame(maxWidth: .infinity, alignment: .leading)
             .padding(.horizontal, Spacing.xl)
-            .padding(.top, Spacing.sm)
+            .padding(.top, OnboardingLayoutMetrics.heroTextGap)
 
             Button {
                 AppPermissions.openSystemSettings()

OSGKeyboard/en.lproj/Localizable.strings

@@ -7,11 +7,11 @@
 "onboarding.welcome.subtitle" = "Your open-source voice keyboard";
 "onboarding.enable.fullAccessNote" = "Full Access lets the keyboard reach the microphone and your LLM API. We never log what you type.";
 "onboarding.permission.mic.title" = "Microphone access";
-"onboarding.permission.mic.body" = "Required for voice input. Audio is processed on your device for transcription.";
+"onboarding.permission.mic.body" = "Voice input requires your permission to use the microphone.";
 "onboarding.permission.mic.allow" = "Allow microphone";
 "onboarding.permission.mic.deniedHint" = "Microphone was denied. Open Settings to enable it, or tap Next to continue.";
 "onboarding.permission.speech.title" = "Speech recognition";
-"onboarding.permission.speech.body" = "On-device speech recognition turns your voice into text. Audio never leaves your device.";
+"onboarding.permission.speech.body" = "On-device speech recognition turns your voice into text.";
 "onboarding.permission.speech.allow" = "Allow speech recognition";
 "onboarding.permission.speech.deniedHint" = "Speech recognition was denied. Open Settings to enable it, or tap Next to continue.";
 "onboarding.permission.openSettings" = "Open Settings";
@@ -43,12 +43,12 @@
 "common.newline" = "Return";
 
 /* Privacy footnote (onboarding welcome page) */
-"privacy.audio.title" = "Audio stays on device";
+"privacy.audio.title" = "On-device transcription";
-"privacy.audio.body" = "Transcribed locally with Apple’s speech engine.";
+"privacy.audio.body" = "Powered by the on-device iOS speech engine.";
-"privacy.network.title" = "Only the polished text is sent";
+"privacy.network.title" = "Automatic text polish";
-"privacy.network.body" = "Sent to your chosen LLM to add structure & punctuation.";
+"privacy.network.body" = "AI formats and polishes your text automatically.";
 "privacy.universal.title" = "Works everywhere";
-"privacy.universal.body" = "WeChat, Notes, Mail, ChatGPT, Claude, Cursor — anywhere a keyboard appears.";
+"privacy.universal.body" = "Chat, email, vibe coding — just speak.";
 
 /* Home */
 "home.status.ready" = "Ready";
@@ -184,7 +184,7 @@
 
 /* Home · Flow session */
 "home.flow.active" = "Voice session active";
-"home.flow.label" = "Voice session";
+"home.flow.label" = "Ready";
 "home.flow.inactive" = "Voice session inactive";
 "home.flow.hint" = "Voice session starts automatically. Switch to any app and tap the keyboard mic to dictate.";
 "home.flow.starting" = "Starting voice session…";

OSGKeyboard/zh-Hans.lproj/Localizable.strings

@@ -7,11 +7,11 @@
 "onboarding.welcome.subtitle" = "你的开源语音输入法";
 "onboarding.enable.fullAccessNote" = "完全访问用于麦克风与 API 配置读取。我们不会记录或上传你的击键内容。";
 "onboarding.permission.mic.title" = "麦克风权限";
-"onboarding.permission.mic.body" = "语音输入需要麦克风。音频在设备端转录，不会上传原始录音。";
+"onboarding.permission.mic.body" = "语音输入需要您授予麦克风权限";
 "onboarding.permission.mic.allow" = "允许麦克风";
 "onboarding.permission.mic.deniedHint" = "麦克风被拒绝。可前往设置开启，或点「下一步」继续。";
 "onboarding.permission.speech.title" = "语音识别权限";
-"onboarding.permission.speech.body" = "端侧语音识别将语音转为文字。音频不会离开你的设备。";
+"onboarding.permission.speech.body" = "端侧语音识别将语音转为文字。";
 "onboarding.permission.speech.allow" = "允许语音识别";
 "onboarding.permission.speech.deniedHint" = "语音识别被拒绝。可前往设置开启，或点「下一步」继续。";
 "onboarding.permission.openSettings" = "打开设置";
@@ -43,12 +43,12 @@
 "common.newline" = "换行";
 
 /* Privacy footnote (onboarding welcome page) */
-"privacy.audio.title" = "音频不出本机";
+"privacy.audio.title" = "支持本地转写";
-"privacy.audio.body" = "由 Apple 端侧引擎转录。";
+"privacy.audio.body" = "支持 iOS 本地引擎转录";
-"privacy.network.title" = "仅发送润色后文字";
+"privacy.network.title" = "文字自动润色";
-"privacy.network.body" = "仅向所选 LLM 发送润色后文字,用于整理结构和标点。";
+"privacy.network.body" = "通过 AI 自动对文字进行排版润色";
 "privacy.universal.title" = "处处可用";
-"privacy.universal.body" = "微信、备忘录、邮件、ChatGPT、Claude、Cursor — 任何键盘出现的地方。";
+"privacy.universal.body" = "聊天、邮件、Vibe Coding 动嘴就行";
 
 /* Home */
 "home.status.ready" = "就绪";
@@ -183,7 +183,7 @@
 
 /* Home · Flow session */
 "home.flow.active" = "语音会话进行中";
-"home.flow.label" = "语音会话";
+"home.flow.label" = "就绪";
 "home.flow.inactive" = "语音会话未启动";
 "home.flow.hint" = "语音会话会自动启动。切到任意 App，点按键盘麦克风即可说话。";
 "home.flow.starting" = "正在启动语音会话…";

OSGKeyboardExt/KeyboardViewController.swift

@@ -66,6 +66,8 @@ public final class KeyboardViewController: UIInputViewController {
     private var flowSessionMonitorTask: Task<Void, Never>?
     private var flowSessionDarwinObserver: FlowSessionDarwinObserver?
     private var isAwaitingFlowResult = false
+    private var lastFlowAutoStartAttempt: TimeInterval = 0
+    private static let flowAutoStartCooldown: TimeInterval = 20
 
     // MARK: - Lifecycle
 
@@ -121,6 +123,7 @@ public final class KeyboardViewController: UIInputViewController {
         state.endRecording        = { [weak self] in self?.pressEnded() }
         state.tapMic              = { [weak self] in self?.toggleRecording() }
         state.openSettings        = { [weak self] in self?.openHostApp() }
+        state.startFlowSession    = { [weak self] in self?.beginFlowStart() }
         state.setMode             = { [weak self] m in self?.persistMode(m) }
         state.setLocale           = { [weak self] l in self?.persistLocale(l) }
         state.setEngineMode       = { [weak self] m in self?.persistEngineMode(m) }
@@ -199,6 +202,24 @@ public final class KeyboardViewController: UIInputViewController {
             }
         }
         wasFlowSessionActive = active
+
+        if !active {
+            maybeAutoStartFlowSession()
+        }
+    }
+
+    /// When the host session is down, proactively jump to the app to start it.
+    private func maybeAutoStartFlowSession() {
+        guard !FlowSessionBridge.isSessionActive() else { return }
+        guard !isPendingFlowStart, !isFlowRecording, !isAwaitingFlowResult else { return }
+        guard state.mode != .off else { return }
+        guard hasFullAccess, AppGroup.isAvailable else { return }
+        guard case .idle = state.phase else { return }
+
+        let now = Date().timeIntervalSince1970
+        guard now - lastFlowAutoStartAttempt >= Self.flowAutoStartCooldown else { return }
+        lastFlowAutoStartAttempt = now
+        beginFlowStart()
     }
 
     private func showFlowSessionExpiredHint() {
@@ -303,6 +324,7 @@ public final class KeyboardViewController: UIInputViewController {
     }
 
     private func beginFlowStart() {
+        guard !isPendingFlowStart else { return }
         isPendingFlowStart = true
         isFlowRecording = false
         flowStartDeadline = Date().timeIntervalSince1970 + FlowWatchdog.startTimeout

OSGKeyboardExt/Views/KeyboardRootView.swift

@@ -19,7 +19,13 @@ import SwiftUI
 import OSGKeyboardShared
 
 private enum KeyboardLayoutMetrics {
-    static let sideActionButtonSize: CGFloat = 44
+    static let sideActionButtonSize: CGFloat = 53
+    static let sideActionIconSize: CGFloat = 19
+    static let sideSpaceBarWidth: CGFloat = 19
+    static let micFlankMinSpacing: CGFloat = 36
+    static let sideActionStackSpacing: CGFloat = 16
+    /// Outer inset for delete / return·space from screen edges (8 pt → 24 pt, +200%).
+    static let sideActionHorizontalInset: CGFloat = Spacing.xs * 3
 }
 
 public struct KeyboardRootView: View {
@@ -36,7 +42,6 @@ public struct KeyboardRootView: View {
     /// it up.
     static let totalHeight: CGFloat = 280
     private static let topBarHeight: CGFloat = 38
-    private static let sideActionStackSpacing: CGFloat = 10
 
     private var palette: ThemePalette {
         colorScheme == .dark ? Palette.dark : Palette.light
@@ -52,14 +57,16 @@ public struct KeyboardRootView: View {
         }
         .padding(.top, 4)
         .padding(.bottom, 6)
-        // Let the system UI chrome show through by drawing no background
+        .background(keyboardBackground)
-        // of our own.
-        .background(Color.clear)
         .frame(height: Self.totalHeight)
         // Feed the resolved palette to all nested chips/buttons.
         .environment(\.themePalette, palette)
     }
 
+    private var keyboardBackground: Color {
+        colorScheme == .dark ? palette.background : Color.clear
+    }
+
     // MARK: - Top bar
 
     private var topBar: some View {
@@ -99,7 +106,8 @@ public struct KeyboardRootView: View {
                 phase: state.phase,
                 transcript: state.lastTranscript,
                 flowSessionActive: state.flowSessionActive,
-                openSettings: state.openSettings
+                openSettings: state.openSettings,
+                startFlowSession: state.startFlowSession
             )
             .frame(height: 22)
 
@@ -117,11 +125,13 @@ public struct KeyboardRootView: View {
     /// HStack vertical alignment keeps delete, mic centre, and the gap
     /// between return/space on one horizontal axis.
     private var micActionRow: some View {
-        HStack(alignment: .center, spacing: 20) {
+        HStack(alignment: .center, spacing: 0) {
             CircularToolbarButton(systemName: "delete.left", label: "delete") {
                 state.deleteBackward()
             }
 
+            Spacer(minLength: KeyboardLayoutMetrics.micFlankMinSpacing)
+
             RecordButton(
                 phase: buttonPhase,
                 level: state.level,
@@ -130,7 +140,9 @@ public struct KeyboardRootView: View {
             )
             .frame(width: 132, height: 132)
 
-            VStack(spacing: Self.sideActionStackSpacing) {
+            Spacer(minLength: KeyboardLayoutMetrics.micFlankMinSpacing)
+
+            VStack(spacing: KeyboardLayoutMetrics.sideActionStackSpacing) {
                 CircularToolbarButton(systemName: "return", label: "newline") {
                     state.insertNewline()
                 }
@@ -139,6 +151,7 @@ public struct KeyboardRootView: View {
                 }
             }
         }
+        .padding(.horizontal, KeyboardLayoutMetrics.sideActionHorizontalInset)
         .frame(maxWidth: .infinity)
     }
 
@@ -191,6 +204,7 @@ private struct TranscriptLine: View {
     let transcript: String
     let flowSessionActive: Bool
     let openSettings: () -> Void
+    let startFlowSession: () -> Void
 
     var body: some View {
         ZStack {
@@ -201,9 +215,18 @@ private struct TranscriptLine: View {
                         .font(TypeStyle.caption)
                         .foregroundStyle(palette.textTertiary)
                 } else {
-                    ExtL10n.text("keyboard.flow.sessionInactive")
+                    HStack(spacing: 6) {
-                        .font(TypeStyle.caption)
+                        ExtL10n.text("keyboard.flow.sessionInactive")
-                        .foregroundStyle(palette.textTertiary)
+                            .font(TypeStyle.caption)
+                            .foregroundStyle(palette.textTertiary)
+                        Button(action: startFlowSession) {
+                            ExtL10n.text("keyboard.flow.start")
+                                .font(TypeStyle.caption)
+                                .foregroundStyle(palette.accent)
+                        }
+                        .buttonStyle(.plain)
+                        .accessibilityHint(ExtL10n.text("keyboard.flow.startA11y"))
+                    }
                 }
             case .requestingPermissions:
                 HStack(spacing: 6) {
@@ -267,6 +290,7 @@ private struct TranscriptLine: View {
 // MARK: - Circular toolbar button
 
 private struct CircularToolbarButton: View {
+    @Environment(\.colorScheme) private var colorScheme
     @Environment(\.themePalette) private var palette: ThemePalette
 
     let systemName: String?
@@ -294,20 +318,26 @@ private struct CircularToolbarButton: View {
                 if spaceStyle {
                     Capsule()
                         .fill(palette.textPrimary)
-                        .frame(width: 16, height: 3)
+                        .frame(width: KeyboardLayoutMetrics.sideSpaceBarWidth, height: 3)
                 } else if let systemName {
                     Image(systemName: systemName)
-                        .font(.system(size: 16, weight: .medium))
+                        .font(.system(size: KeyboardLayoutMetrics.sideActionIconSize, weight: .medium))
                         .foregroundStyle(palette.textPrimary)
                 }
             }
             .frame(width: KeyboardLayoutMetrics.sideActionButtonSize, height: KeyboardLayoutMetrics.sideActionButtonSize)
-            .background(palette.surfaceElevated, in: Circle())
+            .background(sideButtonFill, in: Circle())
-            .overlay(Circle().stroke(palette.divider, lineWidth: 0.5))
+            .overlay(Circle().stroke(palette.dividerStrong, lineWidth: 0.5))
         }
         .buttonStyle(.plain)
         .accessibilityLabel(Text(label))
     }
+
+    private var sideButtonFill: Color {
+        colorScheme == .dark
+            ? Color(red: 0.20, green: 0.20, blue: 0.22)
+            : palette.surfaceElevated
+    }
 }
 
 // MARK: - Status badge

OSGKeyboardExt/en.lproj/Keyboard.strings

@@ -27,12 +27,12 @@
 "common.newline" = "Return";
 
 /* Privacy footnote (onboarding welcome page) */
-"privacy.audio.title" = "Audio stays on device";
+"privacy.audio.title" = "On-device transcription";
-"privacy.audio.body" = "Transcribed locally with Apple’s speech engine.";
+"privacy.audio.body" = "Powered by the on-device iOS speech engine.";
-"privacy.network.title" = "Only the polished text is sent";
+"privacy.network.title" = "Automatic text polish";
-"privacy.network.body" = "Sent to your chosen LLM to add structure & punctuation.";
+"privacy.network.body" = "AI formats and polishes your text automatically.";
 "privacy.universal.title" = "Works everywhere";
-"privacy.universal.body" = "WeChat, Notes, Mail, ChatGPT, Claude, Cursor — anywhere a keyboard appears.";
+"privacy.universal.body" = "Chat, email, vibe coding — just speak.";
 
 /* Home */
 "home.status.ready" = "Ready";
@@ -127,7 +127,9 @@
 "keyboard.tapToTalkA11y" = "Tap to talk";
 
 /* Flow session (keyboard) */
-"keyboard.flow.sessionInactive" = "Open OSGKeyboard to start voice session";
+"keyboard.flow.sessionInactive" = "Voice session off";
+"keyboard.flow.start" = "Start";
+"keyboard.flow.startA11y" = "Start voice session";
 "keyboard.flow.sessionExpired" = "Voice session ended. Open OSGKeyboard to restart.";
 "keyboard.flow.startingSession" = "Starting voice session…";
 "keyboard.flow.transcribing" = "Transcribing…";

OSGKeyboardExt/zh-Hans.lproj/Keyboard.strings

@@ -27,12 +27,12 @@
 "common.newline" = "换行";
 
 /* Privacy footnote (onboarding welcome page) */
-"privacy.audio.title" = "音频不出本机";
+"privacy.audio.title" = "支持本地转写";
-"privacy.audio.body" = "由 Apple 端侧引擎转录。";
+"privacy.audio.body" = "支持 iOS 本地引擎转录";
-"privacy.network.title" = "仅发送润色后文字";
+"privacy.network.title" = "文字自动润色";
-"privacy.network.body" = "仅向所选 LLM 发送润色后文字,用于整理结构和标点。";
+"privacy.network.body" = "通过 AI 自动对文字进行排版润色";
 "privacy.universal.title" = "处处可用";
-"privacy.universal.body" = "微信、备忘录、邮件、ChatGPT、Claude、Cursor — 任何键盘出现的地方。";
+"privacy.universal.body" = "聊天、邮件、Vibe Coding 动嘴就行";
 
 /* Home */
 "home.status.ready" = "就绪";
@@ -127,7 +127,9 @@
 "keyboard.tapToTalkA11y" = "点按说话";
 
 /* Flow session (keyboard) */
-"keyboard.flow.sessionInactive" = "请打开 OSGKeyboard 启动语音会话";
+"keyboard.flow.sessionInactive" = "语音会话未启动";
+"keyboard.flow.start" = "启动";
+"keyboard.flow.startA11y" = "启动语音会话";
 "keyboard.flow.sessionExpired" = "语音会话已结束，请打开 OSGKeyboard 重新启动";
 "keyboard.flow.startingSession" = "正在启动语音会话…";
 "keyboard.flow.transcribing" = "识别中…";

OSGKeyboardShared/Services/FlowContinuousCapture.swift

@@ -25,6 +25,14 @@ private final class FlowCaptureStreamRelay: @unchecked Sendable {
         lock.withLock { self.continuation = continuation }
     }
 
+    func replay(_ snapshots: [AudioBufferSnapshot]) {
+        lock.withLock {
+            for snapshot in snapshots {
+                continuation?.yield(snapshot)
+            }
+        }
+    }
+
     func yield(_ snapshot: AudioBufferSnapshot) {
         lock.withLock { continuation?.yield(snapshot) }
     }
@@ -37,6 +45,34 @@ private final class FlowCaptureStreamRelay: @unchecked Sendable {
     }
 }
 
+/// Rolling pre-roll while utterance gate is closed (~400 ms at typical tap rates).
+private final class FlowPrerollStore: @unchecked Sendable {
+    private let lock = OSAllocatedUnfairLock()
+    private var snapshots: [AudioBufferSnapshot] = []
+    private let maxCount: Int
+
+    init(maxCount: Int = 6) {
+        self.maxCount = maxCount
+    }
+
+    func append(_ snapshot: AudioBufferSnapshot) {
+        lock.withLock {
+            snapshots.append(snapshot)
+            if snapshots.count > maxCount {
+                snapshots.removeFirst(snapshots.count - maxCount)
+            }
+        }
+    }
+
+    func drain() -> [AudioBufferSnapshot] {
+        lock.withLock {
+            let drained = snapshots
+            snapshots.removeAll()
+            return drained
+        }
+    }
+}
+
 /// Rolling bar levels updated from the audio tap; read on the main actor.
 private final class FlowLevelStore: @unchecked Sendable {
     private let lock = OSAllocatedUnfairLock()
@@ -120,6 +156,7 @@ public final class FlowContinuousCapture {
 
     private let audioEngine = AVAudioEngine()
     private let streamRelay = FlowCaptureStreamRelay()
+    private let prerollStore = FlowPrerollStore()
     private let levelStore = FlowLevelStore(barCount: FlowCaptureConstants.levelBarCount)
     private let isUtteranceActive = OSAllocatedUnfairLock(initialState: false)
 
@@ -170,6 +207,7 @@ public final class FlowContinuousCapture {
         if !didInstallTap {
             let utteranceFlag = isUtteranceActive
             let relay = streamRelay
+            let preroll = prerollStore
             let levels = levelStore
             let tap = Self.makeAudioTapBlock(
                 converter: converter,
@@ -177,6 +215,7 @@ public final class FlowContinuousCapture {
                 hwFormat: hwFormat,
                 utteranceFlag: utteranceFlag,
                 levelStore: levels,
+                prerollStore: preroll,
                 streamRelay: relay
             )
             inputNode.installTap(onBus: 0, bufferSize: 4096, format: hwFormat, block: tap)
@@ -213,9 +252,12 @@ public final class FlowContinuousCapture {
 
     /// Begin forwarding downsampled buffers to ASR for one utterance.
     public func beginUtterance() -> AsyncStream<AudioBufferSnapshot> {
-        isUtteranceActive.withLock { $0 = true }
         let (stream, continuation) = AsyncStream<AudioBufferSnapshot>.makeStream()
+        // Bind the consumer before opening the gate so early tap frames
+        // are not dropped on the floor.
         streamRelay.bind(continuation)
+        streamRelay.replay(prerollStore.drain())
+        isUtteranceActive.withLock { $0 = true }
         return stream
     }
 
@@ -241,13 +283,12 @@ public final class FlowContinuousCapture {
         hwFormat: AVAudioFormat,
         utteranceFlag: OSAllocatedUnfairLock<Bool>,
         levelStore: FlowLevelStore,
+        prerollStore: FlowPrerollStore,
         streamRelay: FlowCaptureStreamRelay
     ) -> @Sendable (AVAudioPCMBuffer, AVAudioTime) -> Void {
         return { buffer, _ in
             levelStore.update(from: buffer, barCount: FlowCaptureConstants.levelBarCount)
 
-            guard utteranceFlag.withLock({ $0 }) else { return }
-
             let outFrames = AVAudioFrameCount(
                 Double(buffer.frameLength) * targetFormat.sampleRate / hwFormat.sampleRate
             )
@@ -264,7 +305,12 @@ public final class FlowContinuousCapture {
 
             let snapshot = AudioBufferSnapshot(buffer: outBuffer)
             guard !snapshot.samples.isEmpty else { return }
-            streamRelay.yield(snapshot)
+
+            if utteranceFlag.withLock({ $0 }) {
+                streamRelay.yield(snapshot)
+            } else {
+                prerollStore.append(snapshot)
+            }
         }
     }
 }

OSGKeyboardShared/Services/KeyboardState.swift

@@ -82,6 +82,7 @@ public final class KeyboardState: ObservableObject {
     public var endRecording:        () -> Void = {}
     public var tapMic:              () -> Void = {}
     public var openSettings:        () -> Void = {}
+    public var startFlowSession:    () -> Void = {}
     public var setMode:             (InputMode) -> Void = { _ in }
     public var setLocale:           (String) -> Void = { _ in }
     public var setEngineMode:        (String) -> Void = { _ in }