diff --git a/CHANGELOG.md b/CHANGELOG.md
index 61e7406..99652b3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.5.0] - 2026-07-07
+
+### Added
+- **iCloud settings sync**: engine, language, polish, and Flow preferences now stay in sync across your devices via iCloud (key-value store); a new "Sync settings via iCloud" toggle in Settings controls it. API keys stay on each device and are never uploaded. / **iCloud 设置同步**：引擎、语言、润色与 Flow 偏好现可通过 iCloud（键值存储）在多设备间自动同步；设置中新增「通过 iCloud 同步设置」开关控制此功能。API 密钥仅保留在各自设备本地，绝不上传。
+
+### Changed
+- **Cold-start return guidance**: the handoff screen now points to the bottom Home indicator with a left-to-right swipe animation (instead of the misleading "swipe up"), auto-dismisses once you switch back to your previous app, and closes on a tap anywhere; a "Return to [App]" link is still offered when available. / **冷启动返回引导**：交接页改为指向底部横条并配左向右滑动动画（不再是易误解的「向上滑」），切换回上一个 App 后自动消失，点按任意处即可关闭；可用时仍保留「返回 [App]」文本按钮。
+- **Voice session handoff robustness**: hardened the keyboard→app cold-start flow, including a clearer "Voice session disconnected" hint when the host session drops. / **语音会话交接健壮性**：强化键盘→主 App 的冷启动链路，宿主会话断开时给出更清晰的「语音会话已断开」提示。
+
+### Fixed
+- **Local ASR route-change crash**: dictating with the on-device engine no longer terminates the app with `Failed to create tap due to format mismatch`. On-device `SpeechAnalyzer` warmup reconfigures the shared audio session, which triggers a route change; the tap was reinstalled with a stale hardware format (48 kHz) that no longer matched the live node (24 kHz). The tap now binds to the node's live format (`installTap(format: nil)`) and the downsampling converter rebuilds itself from the actual buffer format, so route churn is handled without crashing. / **本地识别路由切换崩溃**：使用端侧引擎听写不再以 `Failed to create tap due to format mismatch` 崩溃退出。端侧 `SpeechAnalyzer` 预热会重配共享音频会话并触发路由变化，此前重装 tap 时用了过期的硬件采样率（48 kHz），与真实节点（24 kHz）不匹配。现在 tap 绑定节点实时格式（`installTap(format: nil)`），降采样转换器按实际缓冲区格式自适应重建，路由抖动不再导致崩溃。
+- **ASR fallback warning showed raw key**: the weak-network / missing-key fallback hint displayed its localization key (e.g. `flow.warning.polishDegraded`) instead of the translated sentence. These keys live in the `Shared.strings` table but were looked up via the main-app `Localizable` table; they are now resolved through `SharedL10n`. / **ASR 兜底提示显示变量名**：弱网 / 缺少密钥的兜底提示此前显示本地化键名（如 `flow.warning.polishDegraded`）而非译文。这些键位于 `Shared.strings`，却被按主 App 的 `Localizable` 表查找；现改为经 `SharedL10n` 解析。
+- **Flow multi-utterance recognition**: the second (and later) dictation in a session no longer returns "no speech". The session-long downsampling `AVAudioConverter` was being permanently locked by an `.endOfStream` tail-flush, starving every utterance after the first (both on-device and cloud). Trailing speech is still preserved by the live drain loop. Also added recovery from `mediaServicesWereReset`. / **Flow 连续多句识别**：同一会话内第二句及之后不再提示「未识别到语音」。此前会话级降采样 `AVAudioConverter` 被尾音冲刷的 `.endOfStream` 永久锁死，导致首句之后每句都拿不到音频（端侧与云端均受影响）。尾音仍由实时排空环节保留。并新增媒体服务重置（`mediaServicesWereReset`）后的自愈重建。
+- **Local ASR diagnostics**: add chunk-level `SpeechAnalyzer` logs and a settings switch to bypass the custom language model, so local recognition failures can be isolated between Apple assets, CLM attachment, and empty analyzer results. / **本地识别诊断**：新增 `SpeechAnalyzer` 分块级日志，并在设置中加入跳过自定义语言模型的诊断开关，用于区分 Apple 端侧资源、自定义语言模型挂载、以及分析器空结果三类问题。
+
 ## [0.4.1] - 2026-07-06
 
 ### Added
diff --git a/OSGKeyboard/Services/AppURLHandler.swift b/OSGKeyboard/Services/AppURLHandler.swift
index 7848f2d..916b2a6 100644
--- a/OSGKeyboard/Services/AppURLHandler.swift
+++ b/OSGKeyboard/Services/AppURLHandler.swift
@@ -1,29 +1,100 @@
 // AppURLHandler.swift
 // OSGKeyboard · Main App
 //
-// Captures `sourceApplication` from UIKit open-URL options (scheme D).
+// iOS 26 URL handling via the UIScene lifecycle. `application(_:open:options:)`
+// and `UIApplication.OpenURLOptionsKey.sourceApplication` are deprecated in
+// iOS 26; the only supported way to read `sourceApplication` (scheme D
+// host-return whitelist) is `UIOpenURLContext.options.sourceApplication` from a
+// scene delegate — SwiftUI's `.onOpenURL` does not expose it.
 
 import UIKit
 import OSGKeyboardShared
 
-extension Notification.Name {
-    static let osgKeyboardOpenURL = Notification.Name("osgkeyboard.openURL")
+/// Buffers launch/open URLs until the SwiftUI root registers a handler.
+///
+/// On a cold launch the scene delivers the URL in `scene(_:willConnectTo:)`,
+/// which fires *before* the SwiftUI view hierarchy is on screen. Without
+/// buffering, that first `osgkeyboard://startflow` (the keyboard → app
+/// handoff) would be dropped.
+@MainActor
+final class AppOpenURLRouter {
+    static let shared = AppOpenURLRouter()
+
+    private var handler: ((URL) -> Void)?
+    private var pending: [URL] = []
+
+    private init() {}
+
+    /// Register the live handler and flush anything buffered before launch.
+    func register(_ handler: @escaping (URL) -> Void) {
+        self.handler = handler
+        let buffered = pending
+        pending.removeAll()
+        buffered.forEach(handler)
+    }
+
+    func route(_ url: URL) {
+        if let handler {
+            handler(url)
+        } else {
+            pending.append(url)
+        }
+    }
 }
 
 final class AppURLHandler: NSObject, UIApplicationDelegate {
+    /// SwiftUI `@main` apps get no scene delegate by default. Attach ours so
+    /// scene-based URL delivery — the only iOS 26 path to `sourceApplication` —
+    /// reaches `AppSceneDelegate`. We deliberately do NOT create a window here;
+    /// SwiftUI's `WindowGroup` still owns the UI.
     func application(
         _ application: UIApplication,
-        open url: URL,
-        options: [UIApplication.OpenURLOptionsKey: Any] = [:]
-    ) -> Bool {
-        if let source = options[.sourceApplication] as? String {
-            FlowSessionBridge.setPendingHostBundleId(source)
-        }
-        NotificationCenter.default.post(
-            name: .osgKeyboardOpenURL,
-            object: nil,
-            userInfo: ["url": url]
+        configurationForConnecting connectingSceneSession: UISceneSession,
+        options: UIScene.ConnectionOptions
+    ) -> UISceneConfiguration {
+        let configuration = UISceneConfiguration(
+            name: nil,
+            sessionRole: connectingSceneSession.role
         )
-        return true
+        configuration.delegateClass = AppSceneDelegate.self
+        return configuration
+    }
+}
+
+final class AppSceneDelegate: NSObject, UIWindowSceneDelegate {
+    /// Cold launch: the URL arrives in the connection options.
+    func scene(
+        _ scene: UIScene,
+        willConnectTo session: UISceneSession,
+        options connectionOptions: UIScene.ConnectionOptions
+    ) {
+        handle(connectionOptions.urlContexts)
+    }
+
+    /// Warm open while the app is already running or suspended in memory.
+    func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
+        handle(URLContexts)
+    }
+
+    private func handle(_ contexts: Set<UIOpenURLContext>) {
+        // Extract Sendable primitives up front so we never hop a
+        // non-Sendable `UIOpenURLContext` across the actor boundary.
+        let items: [(url: URL, source: String?)] = contexts.map {
+            ($0.url, $0.options.sourceApplication)
+        }
+        guard !items.isEmpty else { return }
+
+        // Scene delegate callbacks are delivered on the main thread.
+        MainActor.assumeIsolated {
+            for item in items {
+                // `sourceApplication` is only non-nil when the caller belongs to
+                // the same Apple Developer Team (our own keyboard extension) —
+                // exactly what the host-return whitelist relies on.
+                if let source = item.source {
+                    FlowSessionBridge.setPendingHostBundleId(source)
+                }
+                AppOpenURLRouter.shared.route(item.url)
+            }
+        }
     }
 }
diff --git a/OSGKeyboard/Services/FlowSessionManager.swift b/OSGKeyboard/Services/FlowSessionManager.swift
index fc6a54f..5096352 100644
--- a/OSGKeyboard/Services/FlowSessionManager.swift
+++ b/OSGKeyboard/Services/FlowSessionManager.swift
@@ -49,6 +49,8 @@ final class FlowSessionManager: ObservableObject {
     private var expiryTask: Task<Void, Never>?
     private var levelTask: Task<Void, Never>?
     private var startTask: Task<Void, Never>?
+    /// Last recording state the poll loop observed — logs only on transition.
+    private var lastObservedRecordingState: FlowSessionKeys.RecordingState = .idle
     private var isUtteranceRecording = false
     /// True from `stopped` until the result/error is written back to App Group.
     private var isUtteranceProcessing = false
@@ -86,6 +88,8 @@ final class FlowSessionManager: ObservableObject {
             isColdStartHandoff = true
         }
 
+        reconcilePersistedFlowStateBeforeStart()
+
         if isActive {
             extendSession(duration: duration)
             if coldStart {
@@ -105,6 +109,33 @@ final class FlowSessionManager: ObservableObject {
         }
     }
 
+    /// Clears App Group Flow state left behind when the host process was killed
+    /// or the device rebooted while the session flag was still set.
+    private func reconcilePersistedFlowStateBeforeStart() {
+        if FlowSessionBridge.isHostStale() {
+            if isActive {
+                endSession()
+            } else {
+                FlowSessionBridge.clearFlowState()
+                FlowLiveActivityController.endSession()
+            }
+            debug("reconciled zombie persisted Flow state")
+            return
+        }
+
+        guard !isActive else { return }
+
+        let orphaned = FlowSessionBridge.recordingState()
+        switch orphaned {
+        case .recording, .stopped, .processing:
+            FlowSessionBridge.setRecordingState(.idle)
+            FlowSessionBridge.clearPendingTranscription()
+            debug("cleared orphaned keyboard recording state: \(orphaned.rawValue)")
+        case .idle, .aborted:
+            break
+        }
+    }
+
     /// Auto-start (or renew) the Flow session on every app foreground when
     /// permissions allow — the "always auto-open, no off switch" policy. Also
     /// clears any orphaned Live Activity a previously force-quit process left
@@ -196,6 +227,9 @@ final class FlowSessionManager: ObservableObject {
             writeHeartbeatIfActive()
         case .background:
             setAppForeground(false)
+            if coldStartContext != nil {
+                dismissColdStartOverlay()
+            }
             beginBackgroundKeepAlive()
         @unknown default:
             break
@@ -328,16 +362,13 @@ final class FlowSessionManager: ObservableObject {
             return
         }
 
-        coldStartContext = FlowColdStartContext(
-            hostEntry: hostEntry,
-            showReturnAlert: hostEntry != nil
-        )
+        coldStartContext = FlowColdStartContext(hostEntry: hostEntry)
     }
 
     private func bindSessionASRIfNeeded(force: Bool = false) {
         let engineMode = store.engineMode
         if !force,
-           let sessionASR,
+           sessionASR != nil,
            sessionASREngineMode == engineMode {
             return
         }
@@ -374,6 +405,11 @@ final class FlowSessionManager: ObservableObject {
 
     private func startPolling() {
         pollingTask?.cancel()
+        lastObservedRecordingState = FlowSessionBridge.recordingState()
+        FlowDiagnostics.log(
+            "polling started: initialRecordingState=\(lastObservedRecordingState.rawValue) " +
+            "container=\(AppGroup.containerPathForDiagnostics)"
+        )
         pollingTask = Task { @MainActor [weak self] in
             while !Task.isCancelled {
                 self?.handleKeyboardSignal()
@@ -383,7 +419,17 @@ final class FlowSessionManager: ObservableObject {
     }
 
     private func handleKeyboardSignal() {
-        switch FlowSessionBridge.recordingState() {
+        let signal = FlowSessionBridge.recordingState()
+        if signal != lastObservedRecordingState {
+            // The single most important cross-process signal: proves whether the
+            // host actually SEES the keyboard's recording state writes.
+            FlowDiagnostics.log(
+                "poll observed recordingState \(lastObservedRecordingState.rawValue) → \(signal.rawValue) " +
+                "[rec=\(isUtteranceRecording) proc=\(isUtteranceProcessing) fg=\(isAppForeground)]"
+            )
+            lastObservedRecordingState = signal
+        }
+        switch signal {
         case .recording:
             guard !isUtteranceRecording, !isUtteranceProcessing else { return }
             beginUtterance()
@@ -431,7 +477,9 @@ final class FlowSessionManager: ObservableObject {
         FlowLiveActivityController.update(phase: .recording)
         FlowDiagnostics.log(
             "beginUtterance engine=\(store.engineMode) " +
-            "asrType=\(type(of: asr)) pipelined=true max=\(Int(FlowSessionKeys.maxUtteranceDuration))s"
+            "asrType=\(type(of: asr)) pipelined=true " +
+            "localCustomLM=\(store.localASRCustomLanguageModelEnabled) " +
+            "max=\(Int(FlowSessionKeys.maxUtteranceDuration))s"
         )
 
         asrTask = Task.detached(priority: .userInitiated) { [weak manager = self] in
@@ -638,12 +686,18 @@ final class FlowSessionManager: ObservableObject {
             // so the keyboard can show the "fill in your key" hint
             // inline rather than a generic failure message. The raw
             // transcript is still delivered — no data loss.
-            let warning = Self.warningFromPolishError(error, engineMode: engineMode) ?? chunkNote
+            let fallback = Self.makeFallbackDelivery(
+                rawText: text,
+                error: error,
+                engineMode: engineMode,
+                chunkWarning: chunkNote
+            )
             FlowDiagnostics.log(
                 "polish failed after \(String(format: "%.1f", Date().timeIntervalSince(polishStarted)))s: " +
                 "\(error.localizedDescription)"
             )
-            FlowSessionBridge.storeTranscriptionResult(text, polishWarning: warning)
+            delivered = fallback.text
+            FlowSessionBridge.storeTranscriptionResult(fallback.text, polishWarning: fallback.polishWarning)
         }
 
         SpeechHistoryStore.shared.recordUtterance(
@@ -684,15 +738,41 @@ final class FlowSessionManager: ObservableObject {
     /// v0.2.0: surface the local-mode cloud-polish error path with a
     /// localised hint ("please fill in your DeepSeek key in Settings")
     /// rather than letting the keyboard show a generic network error.
+    static func makeFallbackDelivery(
+        rawText: String,
+        error: Error,
+        engineMode: String,
+        chunkWarning: String?
+    ) -> TranscriptionDelivery {
+        let fallbackText = TranscriptPostProcessor.cleanRawASRFallback(rawText)
+        let warning = warningFromPolishError(error, engineMode: engineMode)
+            ?? polishDegradedWarning()
+            ?? chunkWarning
+        return TranscriptionDelivery(text: fallbackText, polishWarning: warning)
+    }
+
     private static func warningFromPolishError(_ error: Error, engineMode: String) -> String? {
-        guard let polishError = error as? PolishingService.PolishError,
-              polishError == .missingAPIKey else {
-            return nil
+        if let polishError = error as? PolishingService.PolishError {
+            switch polishError {
+            case .missingAPIKey:
+                if engineMode == "local" {
+                    return SharedL10n.string("flow.warning.localPolishUnavailable")
+                }
+                return SharedL10n.string("flow.warning.cloudPolishMissingKey")
+            case .timeout:
+                return polishDegradedWarning()
+            case .noTranscript:
+                return nil
+            }
         }
-        if engineMode == "local" {
-            return AppL10n.string("flow.warning.localPolishUnavailable")
+        if error is LLMError {
+            return polishDegradedWarning()
         }
-        return AppL10n.string("flow.warning.cloudPolishMissingKey")
+        return nil
+    }
+
+    private static func polishDegradedWarning() -> String? {
+        SharedL10n.string("flow.warning.polishDegraded")
     }
 
     private func asrWaitTimeout() -> TimeInterval {
diff --git a/OSGKeyboard/Services/SpeechHistoryStore.swift b/OSGKeyboard/Services/SpeechHistoryStore.swift
index df13d66..ed61442 100644
--- a/OSGKeyboard/Services/SpeechHistoryStore.swift
+++ b/OSGKeyboard/Services/SpeechHistoryStore.swift
@@ -62,6 +62,12 @@ final class SpeechHistoryStore: ObservableObject {
         )
     }
 
+    func delete(id: UUID) {
+        guard entries.contains(where: { $0.id == id }) else { return }
+        entries.removeAll { $0.id == id }
+        persist()
+    }
+
     func clearAll() {
         entries.removeAll()
         persist()
diff --git a/OSGKeyboard/Views/FlowColdStartOverlay.swift b/OSGKeyboard/Views/FlowColdStartOverlay.swift
index 7b99170..90c5172 100644
--- a/OSGKeyboard/Views/FlowColdStartOverlay.swift
+++ b/OSGKeyboard/Views/FlowColdStartOverlay.swift
@@ -1,14 +1,13 @@
 // FlowColdStartOverlay.swift
 // OSGKeyboard · Main App
 //
-// Minimal cold-start handoff UI: swipe-back guidance and optional return alert.
+// Minimal cold-start handoff UI: bottom-bar swipe guidance and optional return link.
 
 import SwiftUI
 import OSGKeyboardShared
 
 struct FlowColdStartContext: Equatable {
     let hostEntry: HostAppEntry?
-    var showReturnAlert: Bool
 }
 
 struct FlowColdStartOverlay: View {
@@ -18,78 +17,62 @@ struct FlowColdStartOverlay: View {
     let onReturnToHost: () -> Void
     let onDismiss: () -> Void
 
-    @State private var showAlert: Bool
+    @State private var swipeOffset: CGFloat = 0
 
-    init(
-        context: FlowColdStartContext,
-        onReturnToHost: @escaping () -> Void,
-        onDismiss: @escaping () -> Void
-    ) {
-        self.context = context
-        self.onReturnToHost = onReturnToHost
-        self.onDismiss = onDismiss
-        _showAlert = State(initialValue: context.showReturnAlert)
-    }
+    private let homeBarWidth: CGFloat = 134
 
     var body: some View {
         ZStack {
             palette.background.opacity(0.96)
                 .ignoresSafeArea()
 
-            VStack(spacing: Spacing.xl) {
-                Image("OSGBrandMark")
-                    .renderingMode(.template)
-                    .resizable()
-                    .aspectRatio(contentMode: .fit)
-                    .frame(width: 64, height: 64)
-                    .foregroundStyle(palette.accent)
-                    .accessibilityHidden(true)
+            VStack(spacing: 0) {
+                Spacer()
 
-                Text("flow.coldStart.title")
-                    .font(TypeStyle.title3)
-                    .foregroundStyle(palette.textPrimary)
-                    .multilineTextAlignment(.center)
-
-                Text(swipeHintKey)
-                    .font(TypeStyle.body)
-                    .foregroundStyle(palette.textSecondary)
-                    .multilineTextAlignment(.center)
-                    .padding(.horizontal, Spacing.lg)
-
-                swipeHintAnimation
-                    .padding(.top, Spacing.md)
-
-                Button(action: onDismiss) {
-                    Text("flow.coldStart.dismiss")
-                        .font(TypeStyle.body.weight(.semibold))
+                VStack(spacing: Spacing.xl) {
+                    Image("OSGBrandMark")
+                        .renderingMode(.template)
+                        .resizable()
+                        .aspectRatio(contentMode: .fit)
+                        .frame(width: 64, height: 64)
                         .foregroundStyle(palette.accent)
-                        .frame(maxWidth: .infinity)
-                        .padding(.vertical, Spacing.md)
+                        .accessibilityHidden(true)
+
+                    Text("flow.coldStart.title")
+                        .font(TypeStyle.title3)
+                        .foregroundStyle(palette.textPrimary)
+                        .multilineTextAlignment(.center)
+
+                    Text("flow.coldStart.swipeHint")
+                        .font(TypeStyle.body)
+                        .foregroundStyle(palette.textSecondary)
+                        .multilineTextAlignment(.center)
+                        .padding(.horizontal, Spacing.lg)
+
+                    if context.hostEntry != nil {
+                        Button(action: onReturnToHost) {
+                            Text(returnButtonTitle)
+                                .font(TypeStyle.body.weight(.semibold))
+                                .foregroundStyle(palette.accent)
+                        }
+                        .buttonStyle(.plain)
+                    }
                 }
-                .buttonStyle(.plain)
                 .padding(.horizontal, Spacing.xl)
-                .padding(.top, Spacing.lg)
-            }
-            .padding(Spacing.xl)
-        }
-        .alert(alertTitle, isPresented: $showAlert) {
-            if context.hostEntry != nil {
-                Button(returnButtonTitle, action: onReturnToHost)
-            }
-            Button("flow.coldStart.dismiss", role: .cancel, action: onDismiss)
-        } message: {
-            Text("flow.coldStart.alert.message")
-        }
-    }
 
-    private var swipeHintKey: LocalizedStringKey {
-        context.hostEntry == nil
-            ? "flow.coldStart.swipeHint"
-            : "flow.coldStart.swipeHint.withSystemBack"
-    }
+                Spacer()
 
-    private var alertTitle: String {
-        AppL10n.string("flow.coldStart.alert.title")
+                bottomSwipeGuide
+                    .padding(.bottom, Spacing.md)
+
+                Text("flow.coldStart.tapToDismiss")
+                    .font(TypeStyle.caption)
+                    .foregroundStyle(palette.textTertiary)
+                    .padding(.bottom, Spacing.xl)
+            }
+        }
+        .contentShape(Rectangle())
+        .onTapGesture(perform: onDismiss)
     }
 
     private var returnButtonTitle: String {
@@ -100,15 +83,38 @@ struct FlowColdStartOverlay: View {
         return AppL10n.format("flow.coldStart.return.named", appName)
     }
 
-    private var swipeHintAnimation: some View {
+    private var bottomSwipeGuide: some View {
         VStack(spacing: Spacing.sm) {
-            Image(systemName: "chevron.up")
-                .font(.system(size: 20, weight: .semibold))
+            Image(systemName: "arrow.down")
+                .font(.system(size: 14, weight: .semibold))
                 .foregroundStyle(palette.textTertiary)
-            RoundedRectangle(cornerRadius: 3, style: .continuous)
-                .fill(palette.textTertiary.opacity(0.5))
-                .frame(width: 120, height: 5)
+
+            ZStack(alignment: .leading) {
+                RoundedRectangle(cornerRadius: 2.5, style: .continuous)
+                    .fill(palette.textTertiary.opacity(0.35))
+                    .frame(width: homeBarWidth, height: 5)
+
+                Circle()
+                    .fill(palette.accent)
+                    .frame(width: 8, height: 8)
+                    .offset(x: swipeOffset)
+            }
+            .frame(width: homeBarWidth, height: 16)
+
+            HStack(spacing: Spacing.xs) {
+                Image(systemName: "arrow.left")
+                    .font(.system(size: 12, weight: .semibold))
+                Image(systemName: "arrow.right")
+                    .font(.system(size: 12, weight: .semibold))
+            }
+            .foregroundStyle(palette.textTertiary)
         }
         .accessibilityLabel(AppL10n.string("flow.coldStart.swipeAccessibility"))
+        .onAppear {
+            swipeOffset = 0
+            withAnimation(.easeInOut(duration: 1.4).repeatForever(autoreverses: true)) {
+                swipeOffset = homeBarWidth - 8
+            }
+        }
     }
 }
diff --git a/OSGKeyboard/Views/HistoryView.swift b/OSGKeyboard/Views/HistoryView.swift
index 7ed584e..f5c1e87 100644
--- a/OSGKeyboard/Views/HistoryView.swift
+++ b/OSGKeyboard/Views/HistoryView.swift
@@ -32,16 +32,7 @@ struct HistoryView: View {
                 if store.entries.isEmpty {
                     emptyState
                 } else {
-                    ScrollView {
-                        LazyVStack(alignment: .leading, spacing: Spacing.xl) {
-                            ForEach(store.groupedByDay, id: \.day) { group in
-                                daySection(day: group.day, items: group.items)
-                            }
-                        }
-                        .padding(.horizontal, Spacing.lg)
-                        .padding(.vertical, Spacing.md)
-                        .tabBarScrollBottomPadding()
-                    }
+                    list
                 }
             }
             .background(palette.background)
@@ -74,6 +65,38 @@ struct HistoryView: View {
         }
     }
 
+    // MARK: - List
+
+    private var list: some View {
+        List {
+            ForEach(store.groupedByDay, id: \.day) { group in
+                Section {
+                    ForEach(group.items) { entry in
+                        historyRow(entry)
+                            .listRowInsets(EdgeInsets(top: 0, leading: 0, bottom: 0, trailing: 0))
+                            .listRowBackground(palette.surface)
+                            .listRowSeparatorTint(palette.divider)
+                    }
+                    .onDelete { offsets in
+                        delete(items: group.items, at: offsets)
+                    }
+                } header: {
+                    Text(Self.dayFormatter.string(from: group.day))
+                        .font(TypeStyle.caption2)
+                        .foregroundStyle(palette.textTertiary)
+                        .textCase(.uppercase)
+                        .tracking(0.5)
+                }
+            }
+        }
+        .listStyle(.insetGrouped)
+        .listSectionSpacing(Spacing.lg)
+        .scrollContentBackground(.hidden)
+        .background(palette.background)
+        .contentMargins(.top, Spacing.md, for: .scrollContent)
+        .tabBarScrollBottomPadding()
+    }
+
     private var emptyState: some View {
         VStack(spacing: Spacing.sm) {
             Spacer()
@@ -88,30 +111,6 @@ struct HistoryView: View {
         .padding(.horizontal, Spacing.xl)
     }
 
-    private func daySection(day: Date, items: [SpeechHistoryEntry]) -> some View {
-        VStack(alignment: .leading, spacing: Spacing.sm) {
-            Text(Self.dayFormatter.string(from: day))
-                .font(TypeStyle.caption2)
-                .foregroundStyle(palette.textTertiary)
-                .textCase(.uppercase)
-                .tracking(0.5)
-
-            VStack(spacing: 0) {
-                ForEach(Array(items.enumerated()), id: \.element.id) { index, entry in
-                    historyRow(entry)
-                    if index < items.count - 1 {
-                        Divider().background(palette.divider)
-                    }
-                }
-            }
-            .background(palette.surface, in: RoundedRectangle(cornerRadius: Radius.xl, style: .continuous))
-            .overlay(
-                RoundedRectangle(cornerRadius: Radius.xl, style: .continuous)
-                    .stroke(palette.divider, lineWidth: 0.5)
-            )
-        }
-    }
-
     private func historyRow(_ entry: SpeechHistoryEntry) -> some View {
         VStack(alignment: .leading, spacing: Spacing.xxs) {
             Text(Self.timeFormatter.string(from: entry.createdAt))
@@ -126,4 +125,12 @@ struct HistoryView: View {
         .padding(Spacing.md)
         .frame(maxWidth: .infinity, alignment: .leading)
     }
+
+    // MARK: - Mutations
+
+    private func delete(items: [SpeechHistoryEntry], at offsets: IndexSet) {
+        for index in offsets {
+            store.delete(id: items[index].id)
+        }
+    }
 }
diff --git a/OSGKeyboard/Views/LocalEngineSettingsRows.swift b/OSGKeyboard/Views/LocalEngineSettingsRows.swift
index 2681243..c76d2ca 100644
--- a/OSGKeyboard/Views/LocalEngineSettingsRows.swift
+++ b/OSGKeyboard/Views/LocalEngineSettingsRows.swift
@@ -25,6 +25,8 @@ struct LocalModelsGroup: View {
             speechRow
             Divider().background(palette.divider)
             polishRow
+            Divider().background(palette.divider)
+            customLanguageModelDiagnosticRow
         }
         .background(palette.surface, in: RoundedRectangle(cornerRadius: Radius.large, style: .continuous))
         .overlay(
@@ -63,6 +65,25 @@ struct LocalModelsGroup: View {
         .frame(minHeight: SettingsListMetrics.singleLineMinHeight)
     }
 
+    // MARK: Custom language model diagnostic row
+
+    private var customLanguageModelDiagnosticRow: some View {
+        Toggle(isOn: $config.localASRCustomLanguageModelEnabled) {
+            VStack(alignment: .leading, spacing: Spacing.xxs) {
+                Text("settings.localModels.customLM.title")
+                    .font(TypeStyle.body)
+                    .foregroundStyle(palette.textPrimary)
+                Text("settings.localModels.customLM.subtitle")
+                    .font(TypeStyle.caption2)
+                    .foregroundStyle(palette.textTertiary)
+            }
+        }
+        .tint(palette.accent)
+        .padding(.horizontal, Spacing.md)
+        .padding(.vertical, Spacing.sm)
+        .frame(minHeight: SettingsListMetrics.singleLineMinHeight)
+    }
+
     // MARK: Helpers
 
     /// Accent badge naming the engine that backs each local-mode row
diff --git a/OSGKeyboard/Views/MainAppRoot.swift b/OSGKeyboard/Views/MainAppRoot.swift
index 31d7b9d..f10849c 100644
--- a/OSGKeyboard/Views/MainAppRoot.swift
+++ b/OSGKeyboard/Views/MainAppRoot.swift
@@ -38,14 +38,19 @@ struct MainAppRoot: View {
         .onAppear {
             flowManager.setAppForeground(scenePhase == .active)
             flowManager.activateOnForeground()
-            PersonalDictionaryCloudSync.shared.startObservingExternalChanges()
+            AppCloudSync.shared.startObservingExternalChanges()
+            // Registering here also flushes any URL buffered during a cold
+            // launch (the keyboard → app `startflow` handoff arrives via the
+            // scene delegate before this view is on screen).
+            AppOpenURLRouter.shared.register { url in
+                handleIncomingURL(url)
+            }
             Task {
-                await PersonalDictionaryCloudSync.shared.pullAndMergeIfEnabled()
+                await AppCloudSync.shared.pullAllIfEnabled()
             }
         }
-        .onReceive(NotificationCenter.default.publisher(for: .osgKeyboardOpenURL)) { notification in
-            guard let url = notification.userInfo?["url"] as? URL else { return }
-            handleIncomingURL(url)
+        .onReceive(NotificationCenter.default.publisher(for: .settingsDidSyncFromCloud)) { _ in
+            config.reloadFromPersistedStorage()
         }
         .onChange(of: config.hasCompletedOnboarding) { _, done in
             if done {
@@ -59,7 +64,7 @@ struct MainAppRoot: View {
                 flowManager.activateOnForeground()
             }
             Task {
-                await PersonalDictionaryCloudSync.shared.pullAndMergeIfEnabled()
+                await AppCloudSync.shared.pullAllIfEnabled()
             }
         }
     }
diff --git a/OSGKeyboard/Views/SettingsICloudSyncRow.swift b/OSGKeyboard/Views/SettingsICloudSyncRow.swift
new file mode 100644
index 0000000..4da1ddf
--- /dev/null
+++ b/OSGKeyboard/Views/SettingsICloudSyncRow.swift
@@ -0,0 +1,103 @@
+// SettingsICloudSyncRow.swift
+// OSGKeyboard · Main App
+//
+// Settings-row toggle for mirroring user preferences through iCloud KVS.
+// API keys remain in Keychain and are never uploaded.
+
+import SwiftUI
+import OSGKeyboardShared
+
+@MainActor
+struct SettingsICloudSyncRow: View {
+    @Environment(\.themePalette) private var palette: ThemePalette
+
+    @State private var isEnabled: Bool = AppGroupStore().settingsICloudSyncEnabled
+    @State private var syncErrorMessage: String?
+    @State private var isApplyingToggle = false
+
+    private let store = AppGroupStore()
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: Spacing.xxs) {
+            Toggle(isOn: toggleBinding) {
+                VStack(alignment: .leading, spacing: Spacing.xxs) {
+                    Text("settings.appSettings.iCloudSync.title")
+                        .font(TypeStyle.body)
+                        .foregroundStyle(palette.textPrimary)
+                    Text("settings.appSettings.iCloudSync.subtitle")
+                        .font(TypeStyle.caption2)
+                        .foregroundStyle(palette.textTertiary)
+                        .fixedSize(horizontal: false, vertical: true)
+                }
+            }
+            .tint(palette.accent)
+            .disabled(isApplyingToggle)
+
+            if let syncErrorMessage {
+                Text(syncErrorMessage)
+                    .font(TypeStyle.caption2)
+                    .foregroundStyle(.red)
+                    .fixedSize(horizontal: false, vertical: true)
+                    .padding(.top, Spacing.xxs)
+            }
+        }
+        .padding(.horizontal, Spacing.md)
+        .padding(.vertical, Spacing.sm)
+        .frame(minHeight: SettingsListMetrics.singleLineMinHeight, alignment: .leading)
+        .onAppear { reloadFromStore() }
+        .onReceive(
+            NotificationCenter.default.publisher(for: .settingsDidSyncFromCloud)
+        ) { _ in
+            reloadFromStore()
+        }
+    }
+
+    private var toggleBinding: Binding<Bool> {
+        Binding(
+            get: { isEnabled },
+            set: { newValue in
+                guard newValue != isEnabled else { return }
+                if newValue {
+                    enableSync()
+                } else {
+                    disableSync()
+                }
+            }
+        )
+    }
+
+    private func reloadFromStore() {
+        isEnabled = store.settingsICloudSyncEnabled
+    }
+
+    private func enableSync() {
+        isApplyingToggle = true
+        syncErrorMessage = nil
+        Task {
+            do {
+                try await SettingsCloudSync.shared.enableSync()
+                reloadFromStore()
+            } catch let error as SettingsCloudSyncError {
+                isEnabled = false
+                syncErrorMessage = localizedSyncError(error)
+            } catch {
+                isEnabled = false
+                syncErrorMessage = error.localizedDescription
+            }
+            isApplyingToggle = false
+        }
+    }
+
+    private func disableSync() {
+        SettingsCloudSync.shared.disableSync()
+        isEnabled = false
+        syncErrorMessage = nil
+    }
+
+    private func localizedSyncError(_ error: SettingsCloudSyncError) -> String {
+        switch error {
+        case .encodeFailed, .decodeFailed:
+            return AppL10n.string("settings.appSettings.iCloudSync.error.generic")
+        }
+    }
+}
diff --git a/OSGKeyboard/Views/SettingsView.swift b/OSGKeyboard/Views/SettingsView.swift
index b49b0f8..0675d74 100644
--- a/OSGKeyboard/Views/SettingsView.swift
+++ b/OSGKeyboard/Views/SettingsView.swift
@@ -182,6 +182,10 @@ struct SettingsView: View {
                 Divider().background(palette.divider)
 
                 cursorDragNavigationToggleRow
+
+                Divider().background(palette.divider)
+
+                SettingsICloudSyncRow()
             }
             .background(palette.surface, in: RoundedRectangle(cornerRadius: Radius.xl, style: .continuous))
             .overlay(
diff --git a/OSGKeyboard/en.lproj/Localizable.strings b/OSGKeyboard/en.lproj/Localizable.strings
index a85d4a0..772c633 100644
--- a/OSGKeyboard/en.lproj/Localizable.strings
+++ b/OSGKeyboard/en.lproj/Localizable.strings
@@ -368,6 +368,11 @@
 "settings.personalDictionary.iCloudSync.error.tooLarge" = "Dictionary is too large to sync via iCloud. Remove some entries and try again.";
 "settings.personalDictionary.iCloudSync.error.generic" = "Could not sync your dictionary with iCloud. Try again later.";
 
+"settings.iCloudSync.title" = "iCloud Sync";
+"settings.appSettings.iCloudSync.title" = "Sync settings via iCloud";
+"settings.appSettings.iCloudSync.subtitle" = "Keep engine, language, polish, and Flow preferences in sync across your devices. API keys stay on each device.";
+"settings.appSettings.iCloudSync.error.generic" = "Could not sync settings with iCloud. Try again later.";
+
 /* v0.3.0: Polish intensity */
 "settings.polishIntensity.title" = "Polish intensity";
 
@@ -381,15 +386,14 @@
 "settings.flow.inactivity.3h" = "3 hours";
 "settings.flow.inactivity.12h" = "12 hours";
 "settings.flow.inactivity.24h" = "24 hours";
+"settings.localModels.customLM.title" = "Use custom language model";
+"settings.localModels.customLM.subtitle" = "Diagnostic switch. Turn off to test pure Apple on-device recognition if local ASR gets stuck or returns no speech.";
 
 /* Cold-start handoff (scheme B) */
 "flow.coldStart.title" = "Voice is ready";
-"flow.coldStart.swipeHint" = "Swipe up from the bottom edge to return to your previous app.";
-"flow.coldStart.swipeHint.withSystemBack" = "Tap ‹ in the top-left or swipe up from the bottom to return.";
-"flow.coldStart.dismiss" = "Got it";
-"flow.coldStart.swipeAccessibility" = "Swipe up from the bottom to return";
-"flow.coldStart.alert.title" = "Voice is ready";
-"flow.coldStart.alert.message" = "You can return to continue typing, or swipe up from the bottom.";
+"flow.coldStart.swipeHint" = "Swipe right along the bar at the bottom to return to your previous app.";
+"flow.coldStart.swipeAccessibility" = "Swipe right along the bottom bar to return";
+"flow.coldStart.tapToDismiss" = "Tap anywhere to close";
 "flow.coldStart.return.named" = "Return to %@";
 "flow.coldStart.return.generic" = "Return to app";
 
diff --git a/OSGKeyboard/zh-Hans.lproj/Localizable.strings b/OSGKeyboard/zh-Hans.lproj/Localizable.strings
index c1d3f52..8c7f611 100644
--- a/OSGKeyboard/zh-Hans.lproj/Localizable.strings
+++ b/OSGKeyboard/zh-Hans.lproj/Localizable.strings
@@ -367,6 +367,11 @@
 "settings.personalDictionary.iCloudSync.error.tooLarge" = "词库过大，无法通过 iCloud 同步。请删除部分词条后重试。";
 "settings.personalDictionary.iCloudSync.error.generic" = "无法与 iCloud 同步词库，请稍后重试。";
 
+"settings.iCloudSync.title" = "iCloud 同步";
+"settings.appSettings.iCloudSync.title" = "设置 iCloud 同步";
+"settings.appSettings.iCloudSync.subtitle" = "在多台设备间同步引擎、语言、润色和 Flow 偏好。API 密钥仍保留在各设备本地。";
+"settings.appSettings.iCloudSync.error.generic" = "无法与 iCloud 同步设置，请稍后重试。";
+
 /* v0.3.0: 润色强度 */
 "settings.polishIntensity.title" = "润色强度";
 
@@ -380,15 +385,14 @@
 "settings.flow.inactivity.3h" = "3 小时";
 "settings.flow.inactivity.12h" = "12 小时";
 "settings.flow.inactivity.24h" = "24 小时";
+"settings.localModels.customLM.title" = "使用自定义语言模型";
+"settings.localModels.customLM.subtitle" = "诊断开关。本地识别卡住或提示未识别时，可关闭它测试纯 Apple 端侧识别。";
 
 /* 冷启动兜底（方案 B） */
 "flow.coldStart.title" = "语音已就绪";
-"flow.coldStart.swipeHint" = "从屏幕底部边缘向上滑动，返回上一个 App。";
-"flow.coldStart.swipeHint.withSystemBack" = "点左上角 ‹ 或从底部向上滑动返回。";
-"flow.coldStart.dismiss" = "知道了";
-"flow.coldStart.swipeAccessibility" = "从底部向上滑动返回";
-"flow.coldStart.alert.title" = "语音已就绪";
-"flow.coldStart.alert.message" = "可返回继续输入，或从底部向上滑动返回。";
+"flow.coldStart.swipeHint" = "沿屏幕底部的横条，从左向右滑动，返回上一个 App。";
+"flow.coldStart.swipeAccessibility" = "沿底部横条从左向右滑动返回";
+"flow.coldStart.tapToDismiss" = "点按屏幕关闭";
 "flow.coldStart.return.named" = "返回%@";
 "flow.coldStart.return.generic" = "返回 App";
 
diff --git a/OSGKeyboardExt/Services/KeyboardConfigSync.swift b/OSGKeyboardExt/Services/KeyboardConfigSync.swift
index 2f4b8fe..1c4216e 100644
--- a/OSGKeyboardExt/Services/KeyboardConfigSync.swift
+++ b/OSGKeyboardExt/Services/KeyboardConfigSync.swift
@@ -72,7 +72,10 @@ final class KeyboardConfigSync {
 
     func syncOnboardingStateFromAppGroup() {
         let store = AppGroupStore()
-        state.hasCompletedOnboarding = store.hasCompletedOnboarding
+        // Fall back to the reboot-durable Keychain marker so a device restart
+        // does not resurrect the in-keyboard onboarding overlay when the App
+        // Group value transiently reads empty.
+        state.hasCompletedOnboarding = store.hasCompletedOnboarding || Keychain.hasCompletedOnboarding()
         state.onboardingPage = store.onboardingPage
     }
 
diff --git a/OSGKeyboardExt/Services/KeyboardFlowCoordinator.swift b/OSGKeyboardExt/Services/KeyboardFlowCoordinator.swift
index 7f11841..616d3cb 100644
--- a/OSGKeyboardExt/Services/KeyboardFlowCoordinator.swift
+++ b/OSGKeyboardExt/Services/KeyboardFlowCoordinator.swift
@@ -36,6 +36,8 @@ final class KeyboardFlowCoordinator {
     private var wasFlowSessionActive = false
     private var flowSessionMonitorTask: Task<Void, Never>?
     private var isAwaitingFlowResult = false
+    private var lastFlowAutoStartAttempt: TimeInterval = 0
+    private static let flowAutoStartCooldown: TimeInterval = 20
 
     init(
         state: KeyboardState,
@@ -87,10 +89,16 @@ final class KeyboardFlowCoordinator {
         refreshFlowPartialIfNeeded()
         consumePendingFlowDeliveryIfNeeded()
 
-        let active = FlowSessionBridge.isSessionActive()
-        state.flowSessionActive = active
+        recoverFromDeadHostIfNeeded()
 
-        if wasFlowSessionActive && !active && !isFlowRecording && !isPendingFlowStart {
+        if FlowSessionBridge.clearIfHostStale() {
+            debug("cleared zombie Flow session from App Group")
+        }
+
+        let reachable = FlowSessionBridge.isHostReachable()
+        state.flowSessionActive = reachable
+
+        if wasFlowSessionActive && !reachable && !isFlowRecording && !isPendingFlowStart {
             switch state.phase {
             case .recording, .processing:
                 break
@@ -98,7 +106,9 @@ final class KeyboardFlowCoordinator {
                 showFlowSessionExpiredHint()
             }
         }
-        wasFlowSessionActive = active
+        wasFlowSessionActive = reachable
+
+        maybeAutoStartFlowSession()
     }
 
     func toggleRecording() {
@@ -135,7 +145,13 @@ final class KeyboardFlowCoordinator {
 
         detectAndStoreAppContext()
 
-        if FlowSessionBridge.isSessionActive() {
+        let reachable = FlowSessionBridge.isHostReachable()
+        debug(
+            "pressBegan hostReachable=\(reachable) " +
+            "staleness=\(FlowSessionBridge.heartbeatStaleness().map { String(format: "%.1f", $0) } ?? "nil") " +
+            "container=\(AppGroup.containerPathForDiagnostics)"
+        )
+        if reachable {
             startFlowRecording()
         } else {
             beginFlowStart()
@@ -153,6 +169,7 @@ final class KeyboardFlowCoordinator {
         stopUtteranceCountdown()
         ExtensionScreenWakeLock.release()
         FlowSessionBridge.setRecordingState(.stopped)
+        debug("pressEnded wrote .stopped (readback=\(FlowSessionBridge.recordingState().rawValue))")
         state.phase = .processing
         state.lastTranscript = ExtL10n.string("keyboard.flow.transcribing")
         startFlowResultWatchdog()
@@ -225,11 +242,63 @@ final class KeyboardFlowCoordinator {
             }
         }
 
-        if isPendingFlowStart, FlowSessionBridge.isSessionActive() {
+        if isPendingFlowStart, FlowSessionBridge.isHostReachable() {
             completeFlowStartHandoff()
         }
     }
 
+    /// When the host process died mid-utterance, abort local recording / waiting
+    /// so the user is not stuck until the long result watchdog fires.
+    private func recoverFromDeadHostIfNeeded() {
+        guard FlowSessionBridge.isHostStale() else { return }
+
+        if isFlowRecording {
+            isFlowRecording = false
+            stopUtteranceCountdown()
+            ExtensionScreenWakeLock.release()
+            FlowSessionBridge.setRecordingState(.aborted)
+            stopFlowWatchdog()
+            state.level = 0
+            state.phase = .idle
+            state.lastTranscript = ""
+            debug("aborted recording — host heartbeat zombie")
+            return
+        }
+
+        if isAwaitingFlowResult {
+            failHostDisconnected()
+        }
+    }
+
+    /// Restores the pre-ABCD behaviour: when the keyboard appears and the host
+    /// is not reachable, automatically jump to the main app to start Flow.
+    private func maybeAutoStartFlowSession() {
+        guard !FlowSessionBridge.isHostReachable() else { return }
+        guard !isPendingFlowStart, !isFlowRecording, !isAwaitingFlowResult 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 failHostDisconnected() {
+        isAwaitingFlowResult = false
+        isFlowRecording = false
+        isPendingFlowStart = false
+        stopUtteranceCountdown()
+        ExtensionScreenWakeLock.release()
+        FlowSessionBridge.setRecordingState(.aborted)
+        stopFlowWatchdog()
+        state.level = 0
+        let message = ExtL10n.string("keyboard.flow.hostDisconnected")
+        state.phase = .error(.flowSessionExpired, message: message)
+        scheduleAutoClearError()
+        debug("host disconnected while awaiting Flow result")
+    }
+
     private func showFlowSessionExpiredHint() {
         let message = ExtL10n.string("keyboard.flow.sessionExpired")
         state.phase = .error(.flowSessionExpired, message: message)
@@ -252,6 +321,10 @@ final class KeyboardFlowCoordinator {
     }
 
     private func startFlowRecording() {
+        guard FlowSessionBridge.isHostReachable() else {
+            beginFlowStart()
+            return
+        }
         isPendingFlowStart = false
         flowStartDeadline = 0
         stopFlowWatchdog()
@@ -266,7 +339,9 @@ final class KeyboardFlowCoordinator {
         }
         startUtteranceCountdown()
         startFlowLevelWatchdog()
-        debug("startFlowRecording")
+        // Read back in-process to confirm the write landed before we rely on
+        // the host polling it out cross-process.
+        debug("startFlowRecording wrote .recording (readback=\(FlowSessionBridge.recordingState().rawValue))")
     }
 
     private func startUtteranceCountdown() {
@@ -305,7 +380,7 @@ final class KeyboardFlowCoordinator {
         stopFlowWatchdog()
         flowWatchdogTask = Task { @MainActor [weak self] in
             while let self, !Task.isCancelled, self.isPendingFlowStart {
-                if FlowSessionBridge.isSessionActive() {
+                if FlowSessionBridge.isHostReachable() {
                     self.completeFlowStartHandoff()
                     return
                 }
@@ -362,17 +437,20 @@ final class KeyboardFlowCoordinator {
         isAwaitingFlowResult = true
         let startedAt = Date().timeIntervalSince1970
         let resultTimeout = FlowWatchdog.resultTimeout(engineMode: state.engineMode)
+        debug("resultWatchdog started timeout=\(Int(resultTimeout))s engine=\(state.engineMode)")
         flowWatchdogTask = Task { @MainActor [weak self] in
             while let self, !Task.isCancelled {
                 if let delivery = FlowSessionBridge.consumeTranscriptionDelivery() {
                     self.isAwaitingFlowResult = false
                     self.stopFlowWatchdog()
+                    self.debug("resultWatchdog consumed delivery len=\(delivery.text.count)")
                     self.textInserter.handleFlowTranscript(delivery)
                     return
                 }
                 if let error = FlowSessionBridge.consumeTranscriptionError() {
                     self.isAwaitingFlowResult = false
                     self.stopFlowWatchdog()
+                    self.debug("resultWatchdog consumed error kind=\(error.kind.rawValue)")
                     self.state.phase = .error(
                         .fromFlowTranscription(error),
                         message: error.message
@@ -382,9 +460,22 @@ final class KeyboardFlowCoordinator {
                 }
                 self.refreshFlowPartialIfNeeded()
                 let now = Date().timeIntervalSince1970
+                let staleness = FlowSessionBridge.heartbeatStaleness() ?? .infinity
+                if staleness > FlowSessionKeys.heartbeatZombieInterval {
+                    self.debug("resultWatchdog: host heartbeat zombie (staleness=\(String(format: "%.1f", staleness))s)")
+                    self.failHostDisconnected()
+                    return
+                }
+                if !FlowSessionBridge.isHostReachable(),
+                   now - startedAt > FlowSessionKeys.keyboardHostDisconnectFailFast {
+                    self.debug("resultWatchdog: host unreachable after \(String(format: "%.1f", now - startedAt))s")
+                    self.failHostDisconnected()
+                    return
+                }
                 if now - startedAt > resultTimeout {
                     self.isAwaitingFlowResult = false
                     self.stopFlowWatchdog()
+                    self.debug("resultWatchdog TIMEOUT after \(Int(resultTimeout))s — no result from host")
                     let msg = ExtL10n.string("keyboard.flow.resultTimeout")
                     self.state.phase = .error(.flowResultTimeout, message: msg)
                     self.scheduleAutoClearError()
diff --git a/OSGKeyboardExt/en.lproj/Keyboard.strings b/OSGKeyboardExt/en.lproj/Keyboard.strings
index 704e997..581eb9d 100644
--- a/OSGKeyboardExt/en.lproj/Keyboard.strings
+++ b/OSGKeyboardExt/en.lproj/Keyboard.strings
@@ -139,6 +139,7 @@
 "keyboard.flow.startingSession" = "Starting voice session…";
 "keyboard.flow.transcribing" = "Transcribing…";
 "keyboard.flow.resultTimeout" = "Timed out waiting for transcription. Try again.";
+"keyboard.flow.hostDisconnected" = "Voice session disconnected. Open OSGKeyboard to restart.";
 "keyboard.flow.manualOpenHost" = "Could not auto-open the app. Open OSGKeyboard from the Home Screen, then return.";
 
 /* Keyboard status badges */
diff --git a/OSGKeyboardExt/zh-Hans.lproj/Keyboard.strings b/OSGKeyboardExt/zh-Hans.lproj/Keyboard.strings
index 22c69bb..630ea1d 100644
--- a/OSGKeyboardExt/zh-Hans.lproj/Keyboard.strings
+++ b/OSGKeyboardExt/zh-Hans.lproj/Keyboard.strings
@@ -139,6 +139,7 @@
 "keyboard.flow.startingSession" = "正在启动语音会话…";
 "keyboard.flow.transcribing" = "识别中…";
 "keyboard.flow.resultTimeout" = "等待识别结果超时，请重试";
+"keyboard.flow.hostDisconnected" = "语音会话已断开，请打开 OSGKeyboard 重新启动";
 "keyboard.flow.manualOpenHost" = "无法自动跳转，请从主屏幕打开 OSGKeyboard 后返回";
 
 /* Keyboard status badges */
diff --git a/OSGKeyboardShared/Constants/AppGroup.swift b/OSGKeyboardShared/Constants/AppGroup.swift
index deb3eaa..b35a90f 100644
--- a/OSGKeyboardShared/Constants/AppGroup.swift
+++ b/OSGKeyboardShared/Constants/AppGroup.swift
@@ -23,6 +23,15 @@ public enum AppGroup {
         ) != nil
     }()
 
+    /// On-disk container path (or `"nil"`) for diagnostics. When this reads
+    /// `nil` in a process, that process cannot share App Group state — the
+    /// `CFPrefsPlistSource … Container: (null)` console warning comes from here.
+    public static var containerPathForDiagnostics: String {
+        FileManager.default.containerURL(
+            forSecurityApplicationGroupIdentifier: identifier
+        )?.path ?? "nil"
+    }
+
     /// Shared UserDefaults when the App Group suite is available; `nil` otherwise.
     ///
     /// Prefer this in Release builds and in the keyboard extension so callers
diff --git a/OSGKeyboardShared/Models/AppGroupConfiguration.swift b/OSGKeyboardShared/Models/AppGroupConfiguration.swift
index 4730a02..6a1b802 100644
--- a/OSGKeyboardShared/Models/AppGroupConfiguration.swift
+++ b/OSGKeyboardShared/Models/AppGroupConfiguration.swift
@@ -32,10 +32,16 @@ public struct AppGroupConfiguration: Sendable, Equatable {
         public static let personalDictionary = "config.personalDictionary.v1"
         /// When true, the main app mirrors the personal dictionary via iCloud KVS.
         public static let personalDictionaryICloudSyncEnabled = "config.personalDictionary.iCloudSyncEnabled"
+        /// When true, the main app mirrors user settings via iCloud KVS.
+        public static let settingsICloudSyncEnabled = "config.settings.iCloudSyncEnabled"
+        /// Wall-clock stamp of the last settings blob applied from iCloud KVS.
+        public static let settingsCloudUpdatedAt = "config.settings.cloudUpdatedAt"
         /// When true, the host app auto-returns to the source app after a cold-start handoff.
         public static let flowSkipAppSwitch = "config.flowSkipAppSwitch"
         /// Raw `FlowInactivityDuration` value; session expires after this idle window.
         public static let flowInactivityDuration = "config.flowInactivityDuration"
+        /// Diagnostic switch: when false, local ASR skips the custom language model.
+        public static let localASRCustomLanguageModelEnabled = "config.localASR.customLanguageModelEnabled"
     }
 
     // MARK: - Stored fields
@@ -57,10 +63,14 @@ public struct AppGroupConfiguration: Sendable, Equatable {
     public var personalDictionary: PersonalDictionary
     /// Opt-in iCloud KVS sync for the personal dictionary (main app only).
     public var personalDictionaryICloudSyncEnabled: Bool
+    /// Opt-in iCloud KVS sync for user settings (main app only).
+    public var settingsICloudSyncEnabled: Bool
     /// Auto-return to the host app after `startflow` cold start (default on).
     public var flowSkipAppSwitch: Bool
     /// Idle timeout before the Flow session ends; resets on each utterance.
     public var flowInactivityDuration: FlowInactivityDuration
+    /// Whether local `SpeechAnalyzer` should attach the prepared custom language model.
+    public var localASRCustomLanguageModelEnabled: Bool
 
     // MARK: - Derived
 
@@ -164,6 +174,12 @@ public struct AppGroupConfiguration: Sendable, Equatable {
                 }
                 return defaults.bool(forKey: Keys.personalDictionaryICloudSyncEnabled)
             }(),
+            settingsICloudSyncEnabled: {
+                if defaults.object(forKey: Keys.settingsICloudSyncEnabled) == nil {
+                    return true
+                }
+                return defaults.bool(forKey: Keys.settingsICloudSyncEnabled)
+            }(),
             flowSkipAppSwitch: {
                 if defaults.object(forKey: Keys.flowSkipAppSwitch) == nil {
                     return true
@@ -172,7 +188,13 @@ public struct AppGroupConfiguration: Sendable, Equatable {
             }(),
             flowInactivityDuration: FlowInactivityDuration.fromStored(
                 defaults.string(forKey: Keys.flowInactivityDuration)
-            )
+            ),
+            localASRCustomLanguageModelEnabled: {
+                if defaults.object(forKey: Keys.localASRCustomLanguageModelEnabled) == nil {
+                    return true
+                }
+                return defaults.bool(forKey: Keys.localASRCustomLanguageModelEnabled)
+            }()
         )
 
         let preset = LLMProvider.provider(id: config.providerId)
@@ -222,7 +244,9 @@ public struct AppGroupConfiguration: Sendable, Equatable {
         defaults.set(polishIntensity.rawValue, forKey: Keys.polishIntensity)
         defaults.set(flowSkipAppSwitch, forKey: Keys.flowSkipAppSwitch)
         defaults.set(flowInactivityDuration.rawValue, forKey: Keys.flowInactivityDuration)
+        defaults.set(localASRCustomLanguageModelEnabled, forKey: Keys.localASRCustomLanguageModelEnabled)
         defaults.set(personalDictionaryICloudSyncEnabled, forKey: Keys.personalDictionaryICloudSyncEnabled)
+        defaults.set(settingsICloudSyncEnabled, forKey: Keys.settingsICloudSyncEnabled)
         Self.encodePersonalDictionary(personalDictionary, to: defaults)
     }
 
diff --git a/OSGKeyboardShared/Models/ProviderConfig.swift b/OSGKeyboardShared/Models/ProviderConfig.swift
index a49e571..07252f4 100644
--- a/OSGKeyboardShared/Models/ProviderConfig.swift
+++ b/OSGKeyboardShared/Models/ProviderConfig.swift
@@ -78,6 +78,11 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
             guard !isApplyingConfiguration,
                   hasCompletedOnboarding != configuration.hasCompletedOnboarding else { return }
             configuration.hasCompletedOnboarding = hasCompletedOnboarding
+            // Mirror to the reboot-durable Keychain marker so a device restart
+            // can never resurrect the onboarding flow (or lose a replay reset).
+            let newValue = hasCompletedOnboarding
+            OSGLog.config.info("[onboarding] didSet → \(newValue, privacy: .public), mirroring to Keychain")
+            Keychain.setOnboardingCompleted(hasCompletedOnboarding)
             if hasCompletedOnboarding {
                 configuration.onboardingPage = 0
                 onboardingPage = 0
@@ -190,6 +195,19 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
         }
     }
 
+    /// Diagnostic switch: disable to isolate whether the custom language model
+    /// is causing local SpeechAnalyzer to return empty results.
+    @Published public var localASRCustomLanguageModelEnabled: Bool {
+        didSet {
+            guard !isApplyingConfiguration,
+                  localASRCustomLanguageModelEnabled != configuration.localASRCustomLanguageModelEnabled else {
+                return
+            }
+            configuration.localASRCustomLanguageModelEnabled = localASRCustomLanguageModelEnabled
+            persistConfiguration()
+        }
+    }
+
     public var isConfigured: Bool {
         // Local engine uses on-device ASR + built-in DeepSeek polish and
         // does not need a user API key. Cloud needs base URL, key, and model.
@@ -221,6 +239,28 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
         self.defaults = resolvedDefaults
         self.configuration = AppGroupConfiguration.load(fromAvailable: resolvedDefaults)
 
+        // Onboarding completion must survive a device reboot. App Group
+        // UserDefaults can transiently read empty right after boot, which would
+        // falsely re-show onboarding. Trust the durable Keychain marker when the
+        // App Group value looks unset, and backfill it once the App Group value
+        // is confirmed true (covers users onboarded before this safeguard).
+        let appGroupOnboarding = configuration.hasCompletedOnboarding
+        let keychainOnboarding = Keychain.hasCompletedOnboarding()
+        // Distinguish "key absent" (nil → plist not loaded / data-protection race)
+        // from "key present == false" (something actually wrote false).
+        let rawKeyPresent = resolvedDefaults.object(forKey: AppGroupConfiguration.Keys.hasCompletedOnboarding) != nil
+        OSGLog.config.info(
+            "[onboarding] init: appGroup=\(appGroupOnboarding, privacy: .public) (keyPresent=\(rawKeyPresent, privacy: .public)), keychain=\(keychainOnboarding, privacy: .public)"
+        )
+        if appGroupOnboarding {
+            Keychain.setOnboardingCompleted(true)
+        } else if keychainOnboarding {
+            configuration.hasCompletedOnboarding = true
+            OSGLog.config.info("[onboarding] init: App Group read false but Keychain true → restored to true")
+        }
+        let finalOnboarding = configuration.hasCompletedOnboarding
+        OSGLog.config.info("[onboarding] init: final=\(finalOnboarding, privacy: .public)")
+
         isApplyingConfiguration = true
         providerId = configuration.providerId
         baseURL = configuration.baseURL
@@ -239,6 +279,7 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
         polishIntensity = configuration.polishIntensity
         flowSkipAppSwitch = configuration.flowSkipAppSwitch
         flowInactivityDuration = configuration.flowInactivityDuration
+        localASRCustomLanguageModelEnabled = configuration.localASRCustomLanguageModelEnabled
         isApplyingConfiguration = false
     }
 
@@ -255,6 +296,55 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
         if postConfigChanged {
             AppGroupConfigDarwin.postConfigChanged()
         }
+        scheduleSettingsCloudPushIfEnabled()
+    }
+
+    /// Re-read App Group defaults after a cloud pull updates the cache.
+    public func reloadFromPersistedStorage() {
+        var fresh = AppGroupConfiguration.load(fromAvailable: defaults)
+        // Keep the reboot-durable onboarding marker authoritative across cloud
+        // pulls, matching the resilience applied at init.
+        let freshOnboarding = fresh.hasCompletedOnboarding
+        let keychainOnboarding = Keychain.hasCompletedOnboarding()
+        OSGLog.config.info(
+            "[onboarding] reload: appGroup=\(freshOnboarding, privacy: .public), keychain=\(keychainOnboarding, privacy: .public)"
+        )
+        if freshOnboarding {
+            Keychain.setOnboardingCompleted(true)
+        } else if keychainOnboarding {
+            fresh.hasCompletedOnboarding = true
+            OSGLog.config.info("[onboarding] reload: App Group read false but Keychain true → restored to true")
+        }
+        isApplyingConfiguration = true
+        configuration = fresh
+        providerId = fresh.providerId
+        baseURL = fresh.baseURL
+        model = fresh.model
+        modeId = fresh.modeId
+        localeId = fresh.localeId
+        engineMode = fresh.engineMode
+        hasCompletedOnboarding = fresh.hasCompletedOnboarding
+        onboardingPage = fresh.onboardingPage
+        hasAcknowledgedCloudSharing = fresh.hasAcknowledgedCloudSharing
+        uiLanguage = fresh.uiLanguage
+        translationTargetLocaleId = fresh.translationTargetLocaleId
+        handednessPreference = fresh.handednessPreference
+        cursorDragNavigationEnabled = fresh.cursorDragNavigationEnabled
+        polishIntensity = fresh.polishIntensity
+        flowSkipAppSwitch = fresh.flowSkipAppSwitch
+        flowInactivityDuration = fresh.flowInactivityDuration
+        localASRCustomLanguageModelEnabled = fresh.localASRCustomLanguageModelEnabled
+        isSyncingProviderAPIKey = true
+        apiKey = fresh.apiKey
+        isSyncingProviderAPIKey = false
+        isApplyingConfiguration = false
+    }
+
+    private func scheduleSettingsCloudPushIfEnabled() {
+        guard configuration.settingsICloudSyncEnabled else { return }
+        Task { @MainActor in
+            try? await SettingsCloudSync.shared.pushLocalIfEnabled()
+        }
     }
 
     public func apply(preset: LLMProvider) {
@@ -284,11 +374,13 @@ public final class ProviderConfig: ObservableObject, @unchecked Sendable {
         apiKey = ""
         model = preset.defaultModel
         handednessPreference = .left
+        localASRCustomLanguageModelEnabled = true
         hasAcknowledgedCloudSharing = false
         configuration.providerId = preset.id
         configuration.baseURL = preset.defaultBaseURL
         configuration.model = preset.defaultModel
         configuration.handednessPreference = .left
+        configuration.localASRCustomLanguageModelEnabled = true
         configuration.hasAcknowledgedCloudSharing = false
         isApplyingConfiguration = false
         persistConfiguration()
diff --git a/OSGKeyboardShared/Models/SyncedAppSettings.swift b/OSGKeyboardShared/Models/SyncedAppSettings.swift
new file mode 100644
index 0000000..aa5a8cd
--- /dev/null
+++ b/OSGKeyboardShared/Models/SyncedAppSettings.swift
@@ -0,0 +1,107 @@
+// SyncedAppSettings.swift
+// OSGKeyboard · Shared
+//
+// User-facing app settings mirrored through iCloud KVS. Excludes
+// device-local state (onboarding progress, detected app context,
+// personal dictionary blob, and API keys in Keychain).
+
+import Foundation
+
+public struct SyncedAppSettings: Codable, Sendable, Equatable {
+    public var updatedAt: Date
+    public var providerId: String
+    public var baseURL: String
+    public var model: String
+    public var modeId: String
+    public var localeId: String
+    public var engineMode: String
+    public var hasAcknowledgedCloudSharing: Bool
+    public var uiLanguage: AppUILanguage
+    public var translationTargetLocaleId: String
+    public var handednessPreference: HandednessPreference
+    public var cursorDragNavigationEnabled: Bool
+    public var polishIntensity: PolishIntensity
+    public var flowSkipAppSwitch: Bool
+    public var flowInactivityDuration: FlowInactivityDuration
+
+    public init(
+        updatedAt: Date = Date(),
+        providerId: String,
+        baseURL: String,
+        model: String,
+        modeId: String,
+        localeId: String,
+        engineMode: String,
+        hasAcknowledgedCloudSharing: Bool,
+        uiLanguage: AppUILanguage,
+        translationTargetLocaleId: String,
+        handednessPreference: HandednessPreference,
+        cursorDragNavigationEnabled: Bool,
+        polishIntensity: PolishIntensity,
+        flowSkipAppSwitch: Bool,
+        flowInactivityDuration: FlowInactivityDuration
+    ) {
+        self.updatedAt = updatedAt
+        self.providerId = providerId
+        self.baseURL = baseURL
+        self.model = model
+        self.modeId = modeId
+        self.localeId = localeId
+        self.engineMode = engineMode
+        self.hasAcknowledgedCloudSharing = hasAcknowledgedCloudSharing
+        self.uiLanguage = uiLanguage
+        self.translationTargetLocaleId = translationTargetLocaleId
+        self.handednessPreference = handednessPreference
+        self.cursorDragNavigationEnabled = cursorDragNavigationEnabled
+        self.polishIntensity = polishIntensity
+        self.flowSkipAppSwitch = flowSkipAppSwitch
+        self.flowInactivityDuration = flowInactivityDuration
+    }
+}
+
+public extension SyncedAppSettings {
+    /// Build a cloud payload from the current App Group configuration.
+    static func from(configuration: AppGroupConfiguration, updatedAt: Date = Date()) -> SyncedAppSettings {
+        SyncedAppSettings(
+            updatedAt: updatedAt,
+            providerId: configuration.providerId,
+            baseURL: configuration.baseURL,
+            model: configuration.model,
+            modeId: configuration.modeId,
+            localeId: configuration.localeId,
+            engineMode: configuration.engineMode,
+            hasAcknowledgedCloudSharing: configuration.hasAcknowledgedCloudSharing,
+            uiLanguage: configuration.uiLanguage,
+            translationTargetLocaleId: configuration.translationTargetLocaleId,
+            handednessPreference: configuration.handednessPreference,
+            cursorDragNavigationEnabled: configuration.cursorDragNavigationEnabled,
+            polishIntensity: configuration.polishIntensity,
+            flowSkipAppSwitch: configuration.flowSkipAppSwitch,
+            flowInactivityDuration: configuration.flowInactivityDuration
+        )
+    }
+
+    /// Apply syncable fields onto a configuration, preserving device-local
+    /// fields such as onboarding progress and the personal dictionary.
+    func applying(to configuration: inout AppGroupConfiguration) {
+        configuration.providerId = providerId
+        configuration.baseURL = baseURL
+        configuration.model = model
+        configuration.modeId = modeId
+        configuration.localeId = localeId
+        configuration.engineMode = engineMode
+        configuration.hasAcknowledgedCloudSharing = hasAcknowledgedCloudSharing
+        configuration.uiLanguage = uiLanguage
+        configuration.translationTargetLocaleId = translationTargetLocaleId
+        configuration.handednessPreference = handednessPreference
+        configuration.cursorDragNavigationEnabled = cursorDragNavigationEnabled
+        configuration.polishIntensity = polishIntensity
+        configuration.flowSkipAppSwitch = flowSkipAppSwitch
+        configuration.flowInactivityDuration = flowInactivityDuration
+    }
+
+    /// Last-write-wins merge for whole settings blobs.
+    static func merge(local: SyncedAppSettings, remote: SyncedAppSettings) -> SyncedAppSettings {
+        remote.updatedAt >= local.updatedAt ? remote : local
+    }
+}
diff --git a/OSGKeyboardShared/Services/ASRService.swift b/OSGKeyboardShared/Services/ASRService.swift
index 8602358..0f068ae 100644
--- a/OSGKeyboardShared/Services/ASRService.swift
+++ b/OSGKeyboardShared/Services/ASRService.swift
@@ -198,28 +198,30 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
 
     func warmup(locale: Locale) async {
         guard let resolvedLocale = await DictationTranscriber.supportedLocale(equivalentTo: locale) else {
+            Self.debug("warmup locale unsupported requested=\(locale.identifier(.bcp47))")
             return
         }
         let localeID = resolvedLocale.identifier(.bcp47)
         let cachedLocaleID = lock.withLock { chunkPreparedLocaleID }
         if cachedLocaleID == localeID, lock.withLock({ chunkAnalyzerFormat != nil }) {
+            Self.debug("warmup cache hit locale=\(localeID)")
             return
         }
 
-        let lmConfiguration = CustomLanguageModelManager.shared.configurationForTranscription(
-            locale: resolvedLocale
-        )
-        let transcriber = CustomLanguageModelManager.makeDictationTranscriber(
-            locale: resolvedLocale,
-            lmConfiguration: lmConfiguration
+        let setup = Self.makeDiagnosticTranscriber(locale: resolvedLocale)
+        Self.debug(
+            "warmup start locale=\(localeID) customLMEnabled=\(setup.customLanguageModelEnabled) " +
+            "customLMAttached=\(setup.usesCustomLanguageModel) " +
+            "clmState=\(Self.describeCLMState(setup.clmState))"
         )
 
         do {
-            try await Self.prepareAssetsIfNeeded(for: transcriber, locale: resolvedLocale)
+            try await Self.prepareAssetsIfNeeded(for: setup.transcriber, locale: resolvedLocale)
             guard let format = await SpeechAnalyzer.bestAvailableAudioFormat(
-                compatibleWith: [transcriber],
+                compatibleWith: [setup.transcriber],
                 considering: Self.captureFormat
             ) else {
+                Self.debug("warmup format unsupported locale=\(localeID)")
                 return
             }
             lock.withLock {
@@ -236,13 +238,25 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
         guard !samples.isEmpty else { return .success("") }
         if Task.isCancelled { return .cancelled }
 
+        let startedAt = Date()
+        let rms = Self.rms(of: samples)
+        Self.debug(
+            "chunk start samples=\(samples.count) rms=\(String(format: "%.4f", rms)) " +
+            "locale=\(locale.identifier(.bcp47))"
+        )
         do {
             let text = try await transcribeSamples(samples, locale: locale, reuseChunkPrep: true)
             let trimmed = text.trimmingCharacters(in: .whitespacesAndNewlines)
+            Self.debug(
+                "chunk success textLen=\(trimmed.count) elapsed=\(Self.elapsed(startedAt))s " +
+                "empty=\(trimmed.isEmpty)"
+            )
             return trimmed.isEmpty ? .success("") : .success(trimmed)
         } catch is CancellationError {
+            Self.debug("chunk cancelled elapsed=\(Self.elapsed(startedAt))s")
             return .cancelled
         } catch {
+            Self.debug("chunk failed elapsed=\(Self.elapsed(startedAt))s error=\(error.localizedDescription)")
             return .failure(error.localizedDescription)
         }
     }
@@ -257,12 +271,11 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
             throw ASRChunkError.localeUnsupported
         }
         let localeID = resolvedLocale.identifier(.bcp47)
-        let lmConfiguration = CustomLanguageModelManager.shared.configurationForTranscription(
-            locale: resolvedLocale
-        )
-        let transcriber = CustomLanguageModelManager.makeDictationTranscriber(
-            locale: resolvedLocale,
-            lmConfiguration: lmConfiguration
+        let setup = Self.makeDiagnosticTranscriber(locale: resolvedLocale)
+        Self.debug(
+            "chunk setup locale=\(localeID) customLMEnabled=\(setup.customLanguageModelEnabled) " +
+            "customLMAttached=\(setup.usesCustomLanguageModel) " +
+            "clmState=\(Self.describeCLMState(setup.clmState))"
         )
 
         let analyzerFormat: AVAudioFormat
@@ -271,10 +284,14 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
            cachedPrep.0 == localeID,
            let cached = cachedPrep.1 {
             analyzerFormat = cached
+            Self.debug(
+                "chunk using cached analyzer format sr=\(Int(cached.sampleRate)) " +
+                "channels=\(cached.channelCount) common=\(cached.commonFormat.rawValue)"
+            )
         } else {
-            try await Self.prepareAssetsIfNeeded(for: transcriber, locale: resolvedLocale)
+            try await Self.prepareAssetsIfNeeded(for: setup.transcriber, locale: resolvedLocale)
             guard let format = await SpeechAnalyzer.bestAvailableAudioFormat(
-                compatibleWith: [transcriber],
+                compatibleWith: [setup.transcriber],
                 considering: Self.captureFormat
             ) else {
                 throw ASRChunkError.formatUnsupported
@@ -284,6 +301,10 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
                 chunkPreparedLocaleID = localeID
                 chunkAnalyzerFormat = format
             }
+            Self.debug(
+                "chunk prepared analyzer format sr=\(Int(format.sampleRate)) " +
+                "channels=\(format.channelCount) common=\(format.commonFormat.rawValue)"
+            )
         }
 
         let snapshot = AudioBufferSnapshot(samples: samples, sampleRate: 16_000)
@@ -291,12 +312,12 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
             throw ASRChunkError.formatUnsupported
         }
 
-        let analyzer = SpeechAnalyzer(modules: [transcriber])
+        let analyzer = SpeechAnalyzer(modules: [setup.transcriber])
         try await analyzer.prepareToAnalyze(in: analyzerFormat)
 
         let resultsTask = Task<String, Error> {
             var accumulator = ProgressiveDictationTranscriptAccumulator()
-            for try await result in transcriber.results {
+            for try await result in setup.transcriber.results {
                 if Task.isCancelled { break }
                 let text = String(result.text.characters)
                 _ = accumulator.ingest(range: result.range, text: text)
@@ -369,15 +390,15 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
                     }
                     // Each pipelined chunk is ≤ 30 s; long dictation preset keeps a
                     // single chunk coherent (Flow utterances run up to 3 min).
-                    let lmConfiguration = CustomLanguageModelManager.shared.configurationForTranscription(
-                        locale: resolvedLocale
-                    )
-                    let transcriber = CustomLanguageModelManager.makeDictationTranscriber(
-                        locale: resolvedLocale,
-                        lmConfiguration: lmConfiguration
+                    let setup = Self.makeDiagnosticTranscriber(locale: resolvedLocale)
+                    Self.debug(
+                        "stream setup locale=\(resolvedLocale.identifier(.bcp47)) " +
+                        "customLMEnabled=\(setup.customLanguageModelEnabled) " +
+                        "customLMAttached=\(setup.usesCustomLanguageModel) " +
+                        "clmState=\(Self.describeCLMState(setup.clmState))"
                     )
                     do {
-                        try await Self.prepareAssetsIfNeeded(for: transcriber, locale: resolvedLocale)
+                        try await Self.prepareAssetsIfNeeded(for: setup.transcriber, locale: resolvedLocale)
                     } catch {
                         Self.debug("asset prepare failed: \(error.localizedDescription)")
                         continuation.yield(.error(SharedL10n.string("error.asr.assetsNotReady")))
@@ -385,11 +406,11 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
                         return
                     }
 
-                    let newAnalyzer = SpeechAnalyzer(modules: [transcriber])
+                    let newAnalyzer = SpeechAnalyzer(modules: [setup.transcriber])
                     self.lock.withLock { self.analyzer = newAnalyzer }
 
                     guard let analyzerFormat = await SpeechAnalyzer.bestAvailableAudioFormat(
-                        compatibleWith: [transcriber],
+                        compatibleWith: [setup.transcriber],
                         considering: Self.captureFormat
                     ) else {
                         continuation.yield(.error(SharedL10n.string("error.asr.formatUnsupported")))
@@ -405,7 +426,7 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
                     // while `analyzeSequence` drains the input stream.
                     let resultsTask = Task<String, Error> {
                         var accumulator = ProgressiveDictationTranscriptAccumulator()
-                        for try await result in transcriber.results {
+                        for try await result in setup.transcriber.results {
                             if Task.isCancelled { break }
                             let text = String(result.text.characters)
                             guard let full = accumulator.ingest(range: result.range, text: text) else {
@@ -457,23 +478,91 @@ final class SpeechAnalyzerASR: ASRService, @unchecked Sendable {
         }
     }
 
+    private struct DiagnosticTranscriber {
+        let transcriber: DictationTranscriber
+        let customLanguageModelEnabled: Bool
+        let usesCustomLanguageModel: Bool
+        let clmState: CustomLanguageModelManager.PrepareState
+    }
+
+    private static func makeDiagnosticTranscriber(locale: Locale) -> DiagnosticTranscriber {
+        let defaults = AppGroup.defaultsIfAvailable
+        let clmKey = AppGroupConfiguration.Keys.localASRCustomLanguageModelEnabled
+        let clmEnabled = defaults?.object(forKey: clmKey) == nil
+            ? true
+            : (defaults?.bool(forKey: clmKey) ?? true)
+        let clmState = CustomLanguageModelManager.shared.currentState()
+        let lmConfiguration = clmEnabled
+            ? CustomLanguageModelManager.shared.configurationForTranscription(locale: locale)
+            : nil
+        let transcriber = CustomLanguageModelManager.makeDictationTranscriber(
+            locale: locale,
+            lmConfiguration: lmConfiguration
+        )
+        return DiagnosticTranscriber(
+            transcriber: transcriber,
+            customLanguageModelEnabled: clmEnabled,
+            usesCustomLanguageModel: lmConfiguration != nil,
+            clmState: clmState
+        )
+    }
+
+    private static func describeCLMState(_ state: CustomLanguageModelManager.PrepareState) -> String {
+        switch state {
+        case .idle:
+            return "idle"
+        case .preparing:
+            return "preparing"
+        case .ready:
+            return "ready"
+        case .failed(let message):
+            return "failed(\(message))"
+        }
+    }
+
+    private static func rms(of samples: [Float]) -> Float {
+        guard !samples.isEmpty else { return 0 }
+        var sum: Float = 0
+        for sample in samples {
+            sum += sample * sample
+        }
+        return sqrtf(sum / Float(samples.count))
+    }
+
+    private static func elapsed(_ start: Date) -> String {
+        String(format: "%.2f", Date().timeIntervalSince(start))
+    }
+
     private static func debug(_ message: String) {
-        #if DEBUG
-        print("🎙️[ASRService] \(message)")
-        #endif
+        OSGLog.asr.info("\(message, privacy: .public)")
     }
 
     private static func prepareAssetsIfNeeded(
         for transcriber: DictationTranscriber,
         locale: Locale
     ) async throws {
+        let localeID = locale.identifier(.bcp47)
+        let startedAt = Date()
         do {
             _ = try await AssetInventory.reserve(locale: locale)
+            Self.debug("asset reserve ok locale=\(localeID)")
         } catch {
-            // Reservation may already exist or slots are full; continue.
+            // Reservation may already exist or slots are full; continue, but
+            // log it so local-ASR setup failures are not hidden behind a later
+            // "no speech" timeout.
+            Self.debug("asset reserve non-fatal locale=\(localeID) error=\(error.localizedDescription)")
         }
-        if let request = try await AssetInventory.assetInstallationRequest(supporting: [transcriber]) {
-            try await request.downloadAndInstall()
+        do {
+            if let request = try await AssetInventory.assetInstallationRequest(supporting: [transcriber]) {
+                Self.debug("asset install required locale=\(localeID)")
+                try await request.downloadAndInstall()
+                Self.debug("asset install done locale=\(localeID) elapsed=\(elapsed(startedAt))s")
+            } else {
+                Self.debug("asset already installed locale=\(localeID) elapsed=\(elapsed(startedAt))s")
+            }
+        } catch {
+            Self.debug("asset prepare failed locale=\(localeID) elapsed=\(elapsed(startedAt))s error=\(error.localizedDescription)")
+            throw error
         }
     }
 
diff --git a/OSGKeyboardShared/Services/AppGroupStore.swift b/OSGKeyboardShared/Services/AppGroupStore.swift
index 8553c3c..e9de78d 100644
--- a/OSGKeyboardShared/Services/AppGroupStore.swift
+++ b/OSGKeyboardShared/Services/AppGroupStore.swift
@@ -57,6 +57,7 @@ public struct AppGroupStore: @unchecked Sendable {
     public var polishModeForPipeline: PolishingService.PolishMode { configuration.polishModeForPipeline }
     public var polishProviderIdOverride: String? { configuration.polishProviderIdOverride }
     public var isCloudAPIKeyMissingForVoiceInput: Bool { configuration.isCloudAPIKeyMissingForVoiceInput }
+    public var localASRCustomLanguageModelEnabled: Bool { configuration.localASRCustomLanguageModelEnabled }
 
     /// Whether the keyboard top-bar translation chip should render.
     public var isTranslationChipVisible: Bool { true }
@@ -112,6 +113,10 @@ public struct AppGroupStore: @unchecked Sendable {
         mutateConfiguration { $0.polishIntensity = intensity }
     }
 
+    public func setLocalASRCustomLanguageModelEnabled(_ enabled: Bool) {
+        mutateConfiguration { $0.localASRCustomLanguageModelEnabled = enabled }
+    }
+
     public var hasCompletedOnboarding: Bool {
         get { configuration.hasCompletedOnboarding }
         set { setHasCompletedOnboarding(newValue) }
@@ -129,6 +134,8 @@ public struct AppGroupStore: @unchecked Sendable {
                 config.onboardingPage = 0
             }
         }
+        // Mirror to the reboot-durable Keychain marker (keyboard-side completion).
+        Keychain.setOnboardingCompleted(completed)
     }
 
     public func setOnboardingPage(_ page: Int) {
@@ -167,6 +174,22 @@ public struct AppGroupStore: @unchecked Sendable {
         mutateConfiguration { $0.personalDictionaryICloudSyncEnabled = enabled }
     }
 
+    public var settingsICloudSyncEnabled: Bool {
+        get { configuration.settingsICloudSyncEnabled }
+        set { setSettingsICloudSyncEnabled(newValue) }
+    }
+
+    public func setSettingsICloudSyncEnabled(_ enabled: Bool) {
+        mutateConfiguration { $0.settingsICloudSyncEnabled = enabled }
+    }
+
+    /// Timestamp of the last settings blob applied from iCloud KVS.
+    public var settingsCloudUpdatedAt: Date? {
+        let raw = defaults.double(forKey: AppGroupConfiguration.Keys.settingsCloudUpdatedAt)
+        guard raw > 0 else { return nil }
+        return Date(timeIntervalSince1970: raw)
+    }
+
     // MARK: - Client
 
     public func makeClient() -> LLMClient {
diff --git a/OSGKeyboardShared/Services/FlowContinuousCapture.swift b/OSGKeyboardShared/Services/FlowContinuousCapture.swift
index ae52601..78db702 100644
--- a/OSGKeyboardShared/Services/FlowContinuousCapture.swift
+++ b/OSGKeyboardShared/Services/FlowContinuousCapture.swift
@@ -123,6 +123,48 @@ private final class FlowLevelStore: @unchecked Sendable {
     }
 }
 
+/// Route-adaptive downsampling converter, safe to call from the realtime tap.
+///
+/// `AVAudioEngine.installTap(format:)` traps with an **uncatchable** NSException
+/// when the format passed to it does not match the input node's *live* format.
+/// After an audio-route change — which the on-device `SpeechAnalyzer` triggers
+/// during warmup by reconfiguring the shared `AVAudioSession` — the value
+/// returned by `inputNode.outputFormat(forBus:)` can lag behind the real
+/// hardware rate (e.g. it reports 48 kHz while the node has already switched to
+/// 24 kHz). Installing a tap with that stale explicit format crashes the whole
+/// app (`Failed to create tap due to format mismatch`).
+///
+/// We therefore install the tap with `format: nil` (which always uses the
+/// node's live format) and rebuild the sample-rate converter *here* whenever the
+/// incoming buffer's format actually changes, so downsampling to the ASR target
+/// rate is always valid regardless of route churn.
+private final class AdaptiveDownsampler: @unchecked Sendable {
+    // `AVAudioConverter` / `AVAudioFormat` are not `Sendable`, so the state and
+    // the returned converter are guarded manually via the unchecked lock APIs.
+    private let lock = OSAllocatedUnfairLock<(converter: AVAudioConverter, source: AVAudioFormat)?>(uncheckedState: nil)
+    let targetFormat: AVAudioFormat
+
+    init(targetFormat: AVAudioFormat) {
+        self.targetFormat = targetFormat
+    }
+
+    /// Returns a converter valid for `sourceFormat`, rebuilding it lazily when
+    /// the hardware route (and thus the buffer format) changes.
+    func converter(for sourceFormat: AVAudioFormat) -> AVAudioConverter? {
+        lock.withLockUnchecked { state in
+            if let state, state.source == sourceFormat {
+                return state.converter
+            }
+            guard let converter = AVAudioConverter(from: sourceFormat, to: targetFormat) else {
+                state = nil
+                return nil
+            }
+            state = (converter, sourceFormat)
+            return converter
+        }
+    }
+}
+
 @MainActor
 public final class FlowContinuousCapture {
 
@@ -169,16 +211,18 @@ public final class FlowContinuousCapture {
     private let drainTracker = FlowCaptureDrainTracker()
     private let tailSampleCounter = OSAllocatedUnfairLock(initialState: 0)
 
-    private var audioConverter: AVAudioConverter?
+    private var downsampler: AdaptiveDownsampler?
     private var targetFormat: AVAudioFormat?
     private var hwFormat: AVAudioFormat?
     private var drainPolicy = FlowCaptureTailDrainPolicy.flowDefault
 
     private var didInstallTap = false
     private var isRunning = false
+    private var isRebuilding = false
 
     private var routeObserver: NSObjectProtocol?
     private var interruptionObserver: NSObjectProtocol?
+    private var mediaResetObserver: NSObjectProtocol?
     private let log = Logger(subsystem: "com.osgkeyboard.shared", category: "FlowCapture")
 
     public init() {}
@@ -227,11 +271,11 @@ public final class FlowContinuousCapture {
         ) else {
             throw StartError.formatCreateFailed
         }
-        guard let converter = AVAudioConverter(from: hardwareFormat, to: resolvedTargetFormat) else {
-            throw StartError.converterCreateFailed
-        }
 
-        audioConverter = converter
+        // Route-adaptive converter: it rebuilds itself from the live buffer
+        // format inside the tap, so it never assumes a fixed hardware rate.
+        let downsampler = AdaptiveDownsampler(targetFormat: resolvedTargetFormat)
+        self.downsampler = downsampler
         targetFormat = resolvedTargetFormat
         hwFormat = hardwareFormat
 
@@ -249,9 +293,7 @@ public final class FlowContinuousCapture {
         let tailCounter = tailSampleCounter
         let policy = drainPolicy
         let tap = Self.makeAudioTapBlock(
-            converter: converter,
-            targetFormat: resolvedTargetFormat,
-            hwFormat: hardwareFormat,
+            downsampler: downsampler,
             gate: gateLock,
             levelStore: levels,
             prerollStore: preroll,
@@ -260,7 +302,10 @@ public final class FlowContinuousCapture {
             tailSampleCounter: tailCounter,
             drainPolicy: policy
         )
-        inputNode.installTap(onBus: 0, bufferSize: 4096, format: hardwareFormat, block: tap)
+        // `format: nil` binds the tap to the input node's *live* format. Passing
+        // an explicit (possibly stale) format here is what crashed the app on a
+        // route change (48 kHz client vs 24 kHz hardware); nil can never mismatch.
+        inputNode.installTap(onBus: 0, bufferSize: 4096, format: nil, block: tap)
         didInstallTap = true
 
         audioEngine.prepare()
@@ -287,7 +332,7 @@ public final class FlowContinuousCapture {
             audioEngine.stop()
         }
         isRunning = false
-        audioConverter = nil
+        downsampler = nil
         targetFormat = nil
         hwFormat = nil
         try? AVAudioSession.sharedInstance().setActive(
@@ -339,14 +384,35 @@ public final class FlowContinuousCapture {
                 }
             }
         }
+        // Apple QA1749: when the system media server resets, the engine,
+        // converter and audio session all become orphaned and must be
+        // rebuilt from scratch — otherwise capture silently produces no
+        // audio (another cause of "waveform moves but ASR is empty").
+        if mediaResetObserver == nil {
+            mediaResetObserver = center.addObserver(
+                forName: AVAudioSession.mediaServicesWereResetNotification,
+                object: nil,
+                queue: .main
+            ) { [weak self] _ in
+                MainActor.assumeIsolated { self?.handleMediaServicesReset() }
+            }
+        }
     }
 
     private func removeSessionObservers() {
         let center = NotificationCenter.default
         if let routeObserver { center.removeObserver(routeObserver) }
         if let interruptionObserver { center.removeObserver(interruptionObserver) }
+        if let mediaResetObserver { center.removeObserver(mediaResetObserver) }
         routeObserver = nil
         interruptionObserver = nil
+        mediaResetObserver = nil
+    }
+
+    private func handleMediaServicesReset() {
+        guard isRunning else { return }
+        log.info("Media services were reset — rebuilding engine and converter")
+        rebuildEngine()
     }
 
     private func handleRouteChange(reasonRaw: UInt?) {
@@ -388,7 +454,9 @@ public final class FlowContinuousCapture {
     /// Stop and rebuild the engine against the current route, keeping
     /// `isRunning` intact so the session survives the swap transparently.
     private func rebuildEngine() {
-        guard isRunning else { return }
+        guard isRunning, !isRebuilding else { return }
+        isRebuilding = true
+        defer { isRebuilding = false }
         if audioEngine.isRunning {
             audioEngine.stop()
         }
@@ -436,9 +504,15 @@ public final class FlowContinuousCapture {
             try? await Task.sleep(nanoseconds: FlowCaptureConstants.drainPollIntervalNs)
         }
 
-        let flushSamples = flushConverterTailToStream()
-        tailSampleCounter.withLock { $0 += flushSamples }
-
+        // NOTE: We intentionally do NOT signal `.endOfStream` to the shared
+        // downsampling converter here. `AVAudioConverter` is stateful: once its
+        // input block returns `.endOfStream`, the converter is permanently
+        // finished and every subsequent `.haveData` conversion (from the live
+        // tap) returns no data — which silently starved every utterance after
+        // the first (Apple docs + AVAudioConverter reuse guidance). Trailing
+        // speech is already preserved by the live `.draining` forwarding loop
+        // above; the converter's sub-millisecond internal filter tail is not
+        // worth poisoning a session-long converter for.
         streamRelay.finish()
         gate.withLock { $0 = .idle }
 
@@ -466,58 +540,10 @@ public final class FlowContinuousCapture {
         levelStore.snapshot()
     }
 
-    // MARK: - Converter flush
-
-    @discardableResult
-    private func flushConverterTailToStream() -> Int {
-        guard let converter = audioConverter,
-              let targetFormat,
-              let hwFormat else {
-            return 0
-        }
-
-        var flushedSamples = 0
-        let capacity = AVAudioFrameCount(max(512, hwFormat.sampleRate / 20))
-        guard let outBuffer = AVAudioPCMBuffer(pcmFormat: targetFormat, frameCapacity: capacity) else {
-            return 0
-        }
-
-        var endOfStreamSignaled = false
-        while true {
-            outBuffer.frameLength = 0
-            var error: NSError?
-            let status = converter.convert(to: outBuffer, error: &error) { _, outStatus in
-                if endOfStreamSignaled {
-                    outStatus.pointee = .noDataNow
-                    return nil
-                }
-                endOfStreamSignaled = true
-                outStatus.pointee = .endOfStream
-                return nil
-            }
-
-            if status == .error || error != nil {
-                break
-            }
-            guard status == .haveData, outBuffer.frameLength > 0 else {
-                break
-            }
-
-            let snapshot = AudioBufferSnapshot(buffer: outBuffer)
-            guard !snapshot.samples.isEmpty else { break }
-            streamRelay.yield(snapshot)
-            flushedSamples += snapshot.samples.count
-        }
-
-        return flushedSamples
-    }
-
     // MARK: - Audio tap (nonisolated — runs on realtime thread)
 
     private nonisolated static func makeAudioTapBlock(
-        converter: AVAudioConverter,
-        targetFormat: AVAudioFormat,
-        hwFormat: AVAudioFormat,
+        downsampler: AdaptiveDownsampler,
         gate: OSAllocatedUnfairLock<UtteranceGatePhase>,
         levelStore: FlowLevelStore,
         prerollStore: FlowPrerollStore,
@@ -529,8 +555,15 @@ public final class FlowContinuousCapture {
         return { buffer, _ in
             levelStore.update(from: buffer, barCount: FlowCaptureConstants.levelBarCount)
 
+            // Derive the converter from the *live* buffer format so a mid-session
+            // route change (e.g. 48 kHz → 24 kHz) is handled transparently.
+            let sourceFormat = buffer.format
+            let targetFormat = downsampler.targetFormat
+            guard sourceFormat.sampleRate > 0,
+                  let converter = downsampler.converter(for: sourceFormat) else { return }
+
             let outFrames = AVAudioFrameCount(
-                Double(buffer.frameLength) * targetFormat.sampleRate / hwFormat.sampleRate
+                Double(buffer.frameLength) * targetFormat.sampleRate / sourceFormat.sampleRate
             )
             guard outFrames > 0,
                   let outBuffer = AVAudioPCMBuffer(pcmFormat: targetFormat, frameCapacity: outFrames)
diff --git a/OSGKeyboardShared/Services/FlowSessionBridge.swift b/OSGKeyboardShared/Services/FlowSessionBridge.swift
index 65fb653..4c54d1d 100644
--- a/OSGKeyboardShared/Services/FlowSessionBridge.swift
+++ b/OSGKeyboardShared/Services/FlowSessionBridge.swift
@@ -117,9 +117,9 @@ public enum FlowSessionBridge {
 
     // MARK: - Session validity (keyboard)
 
-    /// True when the session contract is still valid (not expired).
-    /// Does not require a fresh heartbeat — the host may be suspended in
-    /// background while the continuous audio session is frozen.
+    /// True when the App Group session contract is still valid (not expired).
+    /// Does **not** mean the host process is alive — use `isHostReachable()` for
+    /// recording gates and "session ready" UI.
     public static func isSessionActive(defaults: UserDefaults? = nil) -> Bool {
         let store = resolvedDefaults(defaults)
         guard store.bool(forKey: FlowSessionKeys.flowSessionActive) else { return false }
@@ -128,19 +128,47 @@ public enum FlowSessionBridge {
         return expires > Date().timeIntervalSince1970
     }
 
+    /// Seconds since the host last wrote `flowHeartbeat`; nil when never written.
+    public static func heartbeatStaleness(defaults: UserDefaults? = nil) -> TimeInterval? {
+        let store = resolvedDefaults(defaults)
+        let heartbeat = store.double(forKey: FlowSessionKeys.flowHeartbeat)
+        guard heartbeat > 0 else { return nil }
+        return Date().timeIntervalSince1970 - heartbeat
+    }
+
     /// True when the host app recently wrote a heartbeat (foreground or
-    /// actively processing). Used for auto-start heuristics, not gating record.
+    /// actively processing). Gating record / "session ready" UI must use this,
+    /// not `isSessionActive()` alone.
     public static func isHostReachable(defaults: UserDefaults? = nil) -> Bool {
         let store = resolvedDefaults(defaults)
         guard isSessionActive(defaults: store) else { return false }
-
-        let heartbeat = store.double(forKey: FlowSessionKeys.flowHeartbeat)
-        guard heartbeat > 0 else { return false }
-
-        let staleness = Date().timeIntervalSince1970 - heartbeat
+        guard let staleness = heartbeatStaleness(defaults: store) else { return false }
         return staleness <= FlowSessionKeys.heartbeatStaleInterval
     }
 
+    /// True when the session contract flag is still set but the host heartbeat
+    /// proves the process is gone (reboot, force-quit, long suspend).
+    public static func isHostStale(
+        staleAfter: TimeInterval = FlowSessionKeys.heartbeatZombieInterval,
+        defaults: UserDefaults? = nil
+    ) -> Bool {
+        let store = resolvedDefaults(defaults)
+        guard isSessionActive(defaults: store) else { return false }
+        guard let staleness = heartbeatStaleness(defaults: store) else { return true }
+        return staleness > staleAfter
+    }
+
+    /// Clears orphaned App Group Flow state when the host is provably dead.
+    @discardableResult
+    public static func clearIfHostStale(
+        staleAfter: TimeInterval = FlowSessionKeys.heartbeatZombieInterval,
+        defaults: UserDefaults? = nil
+    ) -> Bool {
+        guard isHostStale(staleAfter: staleAfter, defaults: defaults) else { return false }
+        clearFlowState(defaults: defaults)
+        return true
+    }
+
     public static func sessionExpiresAt(defaults: UserDefaults? = nil) -> TimeInterval? {
         let store = resolvedDefaults(defaults)
         let expires = store.double(forKey: FlowSessionKeys.flowSessionExpires)
diff --git a/OSGKeyboardShared/Services/FlowSessionKeys.swift b/OSGKeyboardShared/Services/FlowSessionKeys.swift
index b5a8856..7ea238e 100644
--- a/OSGKeyboardShared/Services/FlowSessionKeys.swift
+++ b/OSGKeyboardShared/Services/FlowSessionKeys.swift
@@ -26,9 +26,16 @@ public enum FlowSessionKeys {
     /// Wall-clock timestamp of the last utterance completion or session start.
     public static let lastActivityAt = "flow.lastActivityAt"
 
-    /// Heartbeat older than this while the host is foreground → likely killed.
+    /// Heartbeat older than this → host is not actively reachable for recording.
     public static let heartbeatStaleInterval: TimeInterval = 3
 
+    /// Session flag still set but heartbeat older than this → host process is
+    /// dead (force-quit, reboot). Keyboard / host should clear persisted state.
+    public static let heartbeatZombieInterval: TimeInterval = 60
+
+    /// After mic stop, fail fast when the host heartbeat is gone longer than this.
+    public static let keyboardHostDisconnectFailFast: TimeInterval = 15
+
     /// Legacy fixed session length — prefer `FlowSessionPolicy.sessionDuration()`.
     public static let defaultSessionDuration: TimeInterval = 480
 
diff --git a/OSGKeyboardShared/Services/ICloudSync/AppCloudSync.swift b/OSGKeyboardShared/Services/ICloudSync/AppCloudSync.swift
new file mode 100644
index 0000000..a186f84
--- /dev/null
+++ b/OSGKeyboardShared/Services/ICloudSync/AppCloudSync.swift
@@ -0,0 +1,70 @@
+// AppCloudSync.swift
+// OSGKeyboard · Shared
+//
+// Single entry point for iCloud KVS sync in the main app: preferences
+// toggles, settings payload, and personal dictionary.
+
+import Foundation
+
+@MainActor
+public final class AppCloudSync {
+    public static let shared = AppCloudSync()
+
+    private let kvs: UbiquitousKeyValueStoreing
+    private let makeStore: () -> AppGroupStore
+    private let settingsSync: SettingsCloudSync
+    private let dictionarySync: PersonalDictionaryCloudSync
+    private var externalChangeObserver: NSObjectProtocol?
+
+    public init(
+        kvs: UbiquitousKeyValueStoreing = NSUbiquitousKeyValueStore.default,
+        makeStore: @escaping () -> AppGroupStore = { AppGroupStore() },
+        settingsSync: SettingsCloudSync? = nil,
+        dictionarySync: PersonalDictionaryCloudSync? = nil
+    ) {
+        self.kvs = kvs
+        self.makeStore = makeStore
+        self.settingsSync = settingsSync ?? SettingsCloudSync(kvs: kvs, makeStore: makeStore)
+        self.dictionarySync = dictionarySync ?? PersonalDictionaryCloudSync(kvs: kvs, makeStore: makeStore)
+    }
+
+    public func startObservingExternalChanges() {
+        guard externalChangeObserver == nil else { return }
+        externalChangeObserver = NotificationCenter.default.addObserver(
+            forName: NSUbiquitousKeyValueStore.didChangeExternallyNotification,
+            object: nil,
+            queue: .main
+        ) { [weak self] _ in
+            guard let self else { return }
+            Task { @MainActor in
+                await self.pullAllIfEnabled()
+            }
+        }
+    }
+
+    public func stopObservingExternalChanges() {
+        if let externalChangeObserver {
+            NotificationCenter.default.removeObserver(externalChangeObserver)
+            self.externalChangeObserver = nil
+        }
+    }
+
+    /// Launch / foreground: refresh KVS toggles, then pull payloads.
+    public func pullAllIfEnabled() async {
+        let store = makeStore()
+        ICloudSyncPreferences.migrateLegacyTogglesIfNeeded(kvs: kvs, store: store)
+
+        let toggles = ICloudSyncPreferences.load(from: kvs, store: store)
+        ICloudSyncPreferences.cacheToAppGroup(
+            settingsEnabled: toggles.settings,
+            dictionaryEnabled: toggles.dictionary,
+            store: store
+        )
+
+        await settingsSync.pullAndMergeIfEnabled()
+        await dictionarySync.pullAndMergeIfEnabled()
+    }
+
+    public var settingsSyncService: SettingsCloudSync { settingsSync }
+    public var dictionarySyncService: PersonalDictionaryCloudSync { dictionarySync }
+}
diff --git a/OSGKeyboardShared/Services/ICloudSync/ICloudSyncPreferences.swift b/OSGKeyboardShared/Services/ICloudSync/ICloudSyncPreferences.swift
new file mode 100644
index 0000000..f3d6f05
--- /dev/null
+++ b/OSGKeyboardShared/Services/ICloudSync/ICloudSyncPreferences.swift
@@ -0,0 +1,53 @@
+// ICloudSyncPreferences.swift
+// OSGKeyboard · Shared
+//
+// iCloud KVS is the source of truth for cross-device sync toggles
+// (scheme A). App Group UserDefaults keeps a local cache so the
+// keyboard extension and offline UI can read the last-known state.
+
+import Foundation
+
+public enum ICloudSyncPreferences {
+    public static let settingsEnabledKey = "iCloudSync.settingsEnabled"
+    public static let dictionaryEnabledKey = "personalDictionary.syncEnabled"
+
+    /// Read sync toggles from KVS, falling back to the App Group cache
+    /// when a key has not been uploaded yet.
+    public static func load(from kvs: UbiquitousKeyValueStoreing, store: AppGroupStore) -> (settings: Bool, dictionary: Bool) {
+        let settings = kvs.object(forKey: settingsEnabledKey) as? Bool
+            ?? store.settingsICloudSyncEnabled
+        let dictionary = kvs.object(forKey: dictionaryEnabledKey) as? Bool
+            ?? store.personalDictionaryICloudSyncEnabled
+        return (settings, dictionary)
+    }
+
+    /// Mirror KVS toggles into the App Group cache.
+    public static func cacheToAppGroup(
+        settingsEnabled: Bool,
+        dictionaryEnabled: Bool,
+        store: AppGroupStore
+    ) {
+        store.setSettingsICloudSyncEnabled(settingsEnabled)
+        store.setPersonalDictionaryICloudSyncEnabled(dictionaryEnabled)
+    }
+
+    public static func pushSettingsEnabled(_ enabled: Bool, kvs: UbiquitousKeyValueStoreing) {
+        kvs.set(enabled, forKey: settingsEnabledKey)
+        _ = kvs.synchronize()
+    }
+
+    public static func pushDictionaryEnabled(_ enabled: Bool, kvs: UbiquitousKeyValueStoreing) {
+        kvs.set(enabled, forKey: dictionaryEnabledKey)
+        _ = kvs.synchronize()
+    }
+
+    /// One-time migration: upload locally cached toggles when KVS has no value yet.
+    public static func migrateLegacyTogglesIfNeeded(kvs: UbiquitousKeyValueStoreing, store: AppGroupStore) {
+        if kvs.object(forKey: dictionaryEnabledKey) == nil {
+            pushDictionaryEnabled(store.personalDictionaryICloudSyncEnabled, kvs: kvs)
+        }
+        if kvs.object(forKey: settingsEnabledKey) == nil {
+            pushSettingsEnabled(store.settingsICloudSyncEnabled, kvs: kvs)
+        }
+    }
+}
diff --git a/OSGKeyboardShared/Services/ICloudSync/SettingsCloudSync.swift b/OSGKeyboardShared/Services/ICloudSync/SettingsCloudSync.swift
new file mode 100644
index 0000000..4d1e8d6
--- /dev/null
+++ b/OSGKeyboardShared/Services/ICloudSync/SettingsCloudSync.swift
@@ -0,0 +1,137 @@
+// SettingsCloudSync.swift
+// OSGKeyboard · Shared
+//
+// Mirrors user-facing app settings through iCloud KVS. API keys stay
+// in Keychain and are never uploaded.
+
+import Foundation
+
+public extension Notification.Name {
+    /// Posted after remote settings are applied to the App Group cache.
+    static let settingsDidSyncFromCloud = Notification.Name(
+        "com.osgkeyboard.settings.didSyncFromCloud"
+    )
+}
+
+public enum SettingsCloudSyncError: Error, Equatable, Sendable {
+    case encodeFailed
+    case decodeFailed
+}
+
+@MainActor
+public final class SettingsCloudSync {
+    public static let shared = SettingsCloudSync()
+
+    public static let kvsKey = "appSettings.v1"
+
+    private let kvs: UbiquitousKeyValueStoreing
+    private let makeStore: () -> AppGroupStore
+
+    public init(
+        kvs: UbiquitousKeyValueStoreing = NSUbiquitousKeyValueStore.default,
+        makeStore: @escaping () -> AppGroupStore = { AppGroupStore() }
+    ) {
+        self.kvs = kvs
+        self.makeStore = makeStore
+    }
+
+    public func pullAndMergeIfEnabled() async {
+        let store = makeStore()
+        guard store.settingsICloudSyncEnabled else { return }
+        await pullAndMerge(store: store)
+    }
+
+    public func pushLocalIfEnabled() async throws {
+        let store = makeStore()
+        guard store.settingsICloudSyncEnabled else { return }
+        let local = SyncedAppSettings.from(configuration: store.configurationSnapshot())
+        try push(local)
+    }
+
+    public func enableSync() async throws {
+        let store = makeStore()
+        ICloudSyncPreferences.pushSettingsEnabled(true, kvs: kvs)
+        ICloudSyncPreferences.cacheToAppGroup(
+            settingsEnabled: true,
+            dictionaryEnabled: store.personalDictionaryICloudSyncEnabled,
+            store: store
+        )
+
+        let local = SyncedAppSettings.from(configuration: store.configurationSnapshot())
+        let remote = loadRemote() ?? local
+        let merged = SyncedAppSettings.merge(local: local, remote: remote)
+        apply(merged, to: store, postNotification: false)
+        try push(merged)
+        NotificationCenter.default.post(name: .settingsDidSyncFromCloud, object: nil)
+    }
+
+    public func disableSync() {
+        let store = makeStore()
+        ICloudSyncPreferences.pushSettingsEnabled(false, kvs: kvs)
+        store.setSettingsICloudSyncEnabled(false)
+    }
+
+    public func pullAndMerge(store: AppGroupStore) async {
+        guard store.settingsICloudSyncEnabled else { return }
+        guard let remote = loadRemote() else { return }
+
+        let local = SyncedAppSettings.from(
+            configuration: store.configurationSnapshot(),
+            updatedAt: store.settingsCloudUpdatedAt ?? .distantPast
+        )
+        let merged = SyncedAppSettings.merge(local: local, remote: remote)
+        guard merged != local else { return }
+
+        apply(merged, to: store, postNotification: true)
+    }
+
+    public func push(_ settings: SyncedAppSettings) throws {
+        let encoder = JSONEncoder()
+        encoder.dateEncodingStrategy = .iso8601
+        guard let data = try? encoder.encode(settings) else {
+            throw SettingsCloudSyncError.encodeFailed
+        }
+        kvs.set(data, forKey: Self.kvsKey)
+        _ = kvs.synchronize()
+    }
+
+    public func loadRemote() -> SyncedAppSettings? {
+        guard let data = kvs.data(forKey: Self.kvsKey) else { return nil }
+        return try? decode(data)
+    }
+
+    public func decode(_ data: Data) throws -> SyncedAppSettings {
+        let decoder = JSONDecoder()
+        decoder.dateDecodingStrategy = .iso8601
+        guard let settings = try? decoder.decode(SyncedAppSettings.self, from: data) else {
+            throw SettingsCloudSyncError.decodeFailed
+        }
+        return settings
+    }
+
+    private func apply(
+        _ settings: SyncedAppSettings,
+        to store: AppGroupStore,
+        postNotification: Bool
+    ) {
+        var config = store.configurationSnapshot()
+        settings.applying(to: &config)
+        store.saveConfiguration(config, settingsCloudUpdatedAt: settings.updatedAt)
+        if postNotification {
+            AppGroupConfigDarwin.postConfigChanged()
+            NotificationCenter.default.post(name: .settingsDidSyncFromCloud, object: nil)
+        }
+    }
+}
+
+private extension AppGroupStore {
+    func configurationSnapshot() -> AppGroupConfiguration {
+        AppGroupConfiguration.load(fromAvailable: defaults)
+    }
+
+    func saveConfiguration(_ configuration: AppGroupConfiguration, settingsCloudUpdatedAt: Date) {
+        let config = configuration
+        config.save(to: defaults)
+        defaults.set(settingsCloudUpdatedAt.timeIntervalSince1970, forKey: AppGroupConfiguration.Keys.settingsCloudUpdatedAt)
+    }
+}
diff --git a/OSGKeyboardShared/Services/KeyboardState.swift b/OSGKeyboardShared/Services/KeyboardState.swift
index 3a9e8ee..0a21b78 100644
--- a/OSGKeyboardShared/Services/KeyboardState.swift
+++ b/OSGKeyboardShared/Services/KeyboardState.swift
@@ -80,7 +80,8 @@ public final class KeyboardState: ObservableObject {
     @Published public var onDeviceSupported: Bool = false
     /// Seconds remaining in the current utterance (Flow tap-to-talk).
     @Published public var utteranceRemainingSeconds: Int = Int(FlowSessionKeys.maxUtteranceDuration)
-    /// Whether the host app's Flow voice session is currently valid.
+    /// Whether the host app's Flow voice session is live and reachable (fresh
+    /// heartbeat). Do not use the App Group session flag alone for UI gating.
     @Published public var flowSessionActive: Bool = false
     /// When true, the mic is intentionally disabled (e.g. cloud engine
     /// selected but the provider-specific API key is missing).
diff --git a/OSGKeyboardShared/Services/Keychain.swift b/OSGKeyboardShared/Services/Keychain.swift
index 73b7967..3d6b670 100644
--- a/OSGKeyboardShared/Services/Keychain.swift
+++ b/OSGKeyboardShared/Services/Keychain.swift
@@ -180,4 +180,76 @@ public enum Keychain: @unchecked Sendable {
             throw KeychainError.unexpectedStatus(status)
         }
     }
+
+    // MARK: - Onboarding completion (reboot-durable flag)
+
+    // App Group UserDefaults can transiently read empty right after a device
+    // reboot (data protection / `cfprefsd` not warmed), which made the app
+    // falsely re-show onboarding. This Keychain marker uses the same
+    // `AfterFirstUnlockThisDeviceOnly` class — reliably readable once the app
+    // can run, device-local, never synced — so it stays a trustworthy fallback
+    // that survives the App Group read race.
+    private static let onboardingService = "com.osgkeyboard.onboarding"
+    private static let onboardingAccount = "hasCompletedOnboarding"
+
+    /// Durable "user finished onboarding" marker. `false` when unset or unreadable.
+    public static func hasCompletedOnboarding() -> Bool {
+        let query: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrService as String: onboardingService,
+            kSecAttrAccount as String: onboardingAccount,
+            kSecReturnData as String: true,
+            kSecMatchLimit as String: kSecMatchLimitOne,
+        ]
+        var result: CFTypeRef?
+        let status = SecItemCopyMatching(query as CFDictionary, &result)
+        guard status == errSecSuccess,
+              let data = result as? Data,
+              let str = String(data: data, encoding: .utf8) else {
+            OSGLog.config.info("[onboarding] Keychain read: status=\(status, privacy: .public) → false")
+            return false
+        }
+        let completed = str == "1"
+        OSGLog.config.info(
+            "[onboarding] Keychain read: status=ok value=\(str, privacy: .public) → \(completed, privacy: .public)"
+        )
+        return completed
+    }
+
+    /// Mirror the onboarding-completed flag. Best-effort and idempotent — a
+    /// no-op when the stored value already matches, so it can be called from
+    /// frequently-saved config paths without Keychain churn.
+    public static func setOnboardingCompleted(_ completed: Bool) {
+        guard hasCompletedOnboarding() != completed else {
+            OSGLog.config.info("[onboarding] Keychain write skipped (already \(completed, privacy: .public))")
+            return
+        }
+
+        let baseQuery: [String: Any] = [
+            kSecClass as String: kSecClassGenericPassword,
+            kSecAttrService as String: onboardingService,
+            kSecAttrAccount as String: onboardingAccount,
+        ]
+
+        guard completed else {
+            let delStatus = SecItemDelete(baseQuery as CFDictionary)
+            OSGLog.config.info("[onboarding] Keychain delete: status=\(delStatus, privacy: .public)")
+            return
+        }
+
+        let data = Data("1".utf8)
+        let updateStatus = SecItemUpdate(
+            baseQuery as CFDictionary,
+            [kSecValueData as String: data] as CFDictionary
+        )
+        if updateStatus == errSecItemNotFound {
+            var addQuery = baseQuery
+            addQuery[kSecValueData as String] = data
+            addQuery[kSecAttrAccessible as String] = kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly
+            let addStatus = SecItemAdd(addQuery as CFDictionary, nil)
+            OSGLog.config.info("[onboarding] Keychain add: status=\(addStatus, privacy: .public)")
+        } else {
+            OSGLog.config.info("[onboarding] Keychain update: status=\(updateStatus, privacy: .public)")
+        }
+    }
 }
diff --git a/OSGKeyboardShared/Services/LiveDictationController.swift b/OSGKeyboardShared/Services/LiveDictationController.swift
index 8a82692..fa4d6ac 100644
--- a/OSGKeyboardShared/Services/LiveDictationController.swift
+++ b/OSGKeyboardShared/Services/LiveDictationController.swift
@@ -565,7 +565,12 @@ public final class LiveDictationController: ObservableObject {
             try? await Task.sleep(nanoseconds: 20_000_000)
         }
 
-        _ = flushConverterTailToStream()
+        // Trailing speech is preserved by the live `.draining` forwarding
+        // loop above. We deliberately do NOT signal `.endOfStream` to the
+        // converter to squeeze its internal filter tail: that both races the
+        // still-running audio-thread tap on the same non-thread-safe converter
+        // and (in reused-converter paths) permanently locks it. The dropped
+        // tail is sub-millisecond and inaudible.
         streamRelay.finish()
         teardownCaptureEngine()
         captureGate.withLock { $0 = .idle }
@@ -580,50 +585,6 @@ public final class LiveDictationController: ObservableObject {
         )
     }
 
-    @discardableResult
-    private func flushConverterTailToStream() -> Int {
-        guard let converter = audioConverter,
-              let targetFormat,
-              let hwFormat else {
-            return 0
-        }
-
-        var flushedSamples = 0
-        let capacity = AVAudioFrameCount(max(512, hwFormat.sampleRate / 20))
-        guard let outBuffer = AVAudioPCMBuffer(pcmFormat: targetFormat, frameCapacity: capacity) else {
-            return 0
-        }
-
-        var endOfStreamSignaled = false
-        while true {
-            outBuffer.frameLength = 0
-            var error: NSError?
-            let status = converter.convert(to: outBuffer, error: &error) { _, outStatus in
-                if endOfStreamSignaled {
-                    outStatus.pointee = .noDataNow
-                    return nil
-                }
-                endOfStreamSignaled = true
-                outStatus.pointee = .endOfStream
-                return nil
-            }
-
-            if status == .error || error != nil {
-                break
-            }
-            guard status == .haveData, outBuffer.frameLength > 0 else {
-                break
-            }
-
-            let snapshot = AudioBufferSnapshot(buffer: outBuffer)
-            guard !snapshot.samples.isEmpty else { break }
-            streamRelay.yield(snapshot)
-            flushedSamples += snapshot.samples.count
-        }
-
-        return flushedSamples
-    }
-
     private func teardownCaptureEngine() {
         if didInstallTap {
             audioEngine.inputNode.removeTap(onBus: 0)
diff --git a/OSGKeyboardShared/Services/PersonalDictionaryCloudSync/PersonalDictionaryCloudSync.swift b/OSGKeyboardShared/Services/PersonalDictionaryCloudSync/PersonalDictionaryCloudSync.swift
index 58261ba..b1aaeff 100644
--- a/OSGKeyboardShared/Services/PersonalDictionaryCloudSync/PersonalDictionaryCloudSync.swift
+++ b/OSGKeyboardShared/Services/PersonalDictionaryCloudSync/PersonalDictionaryCloudSync.swift
@@ -80,7 +80,12 @@ public final class PersonalDictionaryCloudSync {
     /// Enable sync: merge local + remote, persist locally, then upload.
     public func enableSync() async throws {
         let store = makeStore()
-        store.setPersonalDictionaryICloudSyncEnabled(true)
+        ICloudSyncPreferences.pushDictionaryEnabled(true, kvs: kvs)
+        ICloudSyncPreferences.cacheToAppGroup(
+            settingsEnabled: store.settingsICloudSyncEnabled,
+            dictionaryEnabled: true,
+            store: store
+        )
 
         let local = store.personalDictionary
         let remote = loadRemote() ?? .empty
@@ -90,7 +95,9 @@ public final class PersonalDictionaryCloudSync {
     }
 
     public func disableSync() {
-        makeStore().setPersonalDictionaryICloudSyncEnabled(false)
+        let store = makeStore()
+        ICloudSyncPreferences.pushDictionaryEnabled(false, kvs: kvs)
+        store.setPersonalDictionaryICloudSyncEnabled(false)
     }
 
     // MARK: - Core operations
diff --git a/OSGKeyboardShared/Services/PersonalDictionaryCloudSync/UbiquitousKeyValueStoreing.swift b/OSGKeyboardShared/Services/PersonalDictionaryCloudSync/UbiquitousKeyValueStoreing.swift
index 0581a78..5c5c767 100644
--- a/OSGKeyboardShared/Services/PersonalDictionaryCloudSync/UbiquitousKeyValueStoreing.swift
+++ b/OSGKeyboardShared/Services/PersonalDictionaryCloudSync/UbiquitousKeyValueStoreing.swift
@@ -8,6 +8,8 @@ import Foundation
 public protocol UbiquitousKeyValueStoreing: AnyObject {
     func data(forKey key: String) -> Data?
     func set(_ value: Data?, forKey key: String)
+    func object(forKey key: String) -> Any?
+    func set(_ value: Any?, forKey key: String)
     @discardableResult
     func synchronize() -> Bool
 }
diff --git a/OSGKeyboardShared/Services/TranscriptPostProcessor.swift b/OSGKeyboardShared/Services/TranscriptPostProcessor.swift
index 0831826..bf82888 100644
--- a/OSGKeyboardShared/Services/TranscriptPostProcessor.swift
+++ b/OSGKeyboardShared/Services/TranscriptPostProcessor.swift
@@ -43,6 +43,19 @@ public enum TranscriptPostProcessor: Sendable {
         text.trimmingCharacters(in: .whitespacesAndNewlines)
     }
 
+    /// Conservative cleanup for raw ASR fallback delivery. This is used when
+    /// polish/translation cannot run, so it must not rewrite meaning or invent
+    /// punctuation; it only removes formatting artifacts that ASR/chunking can
+    /// introduce.
+    public static func cleanRawASRFallback(_ text: String) -> String {
+        var result = text.trimmingCharacters(in: .whitespacesAndNewlines)
+        result = repairMidSentenceLineBreaks(result)
+        result = collapseHorizontalWhitespace(result)
+        result = removeCJKBoundarySpaces(result)
+        result = normalizePunctuationSpacing(result)
+        return normalizeWhitespaceAndPunctuation(result)
+    }
+
     // MARK: - Post-LLM pipeline
 
     /// Apply deterministic cleanup and quality gate to LLM output.
@@ -220,6 +233,53 @@ public enum TranscriptPostProcessor: Sendable {
         return result.trimmingCharacters(in: .whitespacesAndNewlines)
     }
 
+    private static func collapseHorizontalWhitespace(_ text: String) -> String {
+        text.replacingOccurrences(
+            of: #"[^\S\r\n]+"#,
+            with: " ",
+            options: .regularExpression
+        )
+    }
+
+    private static func removeCJKBoundarySpaces(_ text: String) -> String {
+        var output = ""
+        let characters = Array(text)
+        for index in characters.indices {
+            let current = characters[index]
+            if current.isWhitespace,
+               let previous = previousNonWhitespace(in: characters, before: index),
+               let next = nextNonWhitespace(in: characters, after: index),
+               shouldDropSpaceBetween(previous: previous, next: next) {
+                continue
+            }
+            output.append(current)
+        }
+        return output
+    }
+
+    private static func normalizePunctuationSpacing(_ text: String) -> String {
+        var output = ""
+        let characters = Array(text)
+        for index in characters.indices {
+            let current = characters[index]
+            if current.isWhitespace,
+               let next = nextNonWhitespace(in: characters, after: index),
+               isClosingPunctuation(next) {
+                continue
+            }
+            if isOpeningPunctuation(current),
+               let next = nextNonWhitespace(in: characters, after: index),
+               next.isWhitespace {
+                output.append(current)
+                continue
+            }
+            output.append(current)
+        }
+        return output
+            .replacingOccurrences(of: #"([（「“])\s+"#, with: "$1", options: .regularExpression)
+            .replacingOccurrences(of: #"\s+([，。！？；：、,.!?;:])"#, with: "$1", options: .regularExpression)
+    }
+
     // MARK: - Prefix / quote cleanup
 
     public static func stripExplanatoryPrefix(from text: String) -> String {
@@ -271,6 +331,41 @@ public enum TranscriptPostProcessor: Sendable {
         return (pAscii && nAscii) ? " " : ""
     }
 
+    private static func previousNonWhitespace(in characters: [Character], before index: Int) -> Character? {
+        guard index > characters.startIndex else { return nil }
+        for i in stride(from: index - 1, through: characters.startIndex, by: -1) {
+            if !characters[i].isWhitespace { return characters[i] }
+        }
+        return nil
+    }
+
+    private static func nextNonWhitespace(in characters: [Character], after index: Int) -> Character? {
+        let nextIndex = index + 1
+        guard nextIndex < characters.endIndex else { return nil }
+        for i in nextIndex..<characters.endIndex {
+            if !characters[i].isWhitespace { return characters[i] }
+        }
+        return nil
+    }
+
+    private static func shouldDropSpaceBetween(previous: Character, next: Character) -> Bool {
+        (isCJKCharacter(previous) && isCJKCharacter(next)) || isClosingPunctuation(next)
+    }
+
+    private static func isCJKCharacter(_ character: Character) -> Bool {
+        character.unicodeScalars.contains(where: isCJKScalar)
+    }
+
+    private static func isClosingPunctuation(_ character: Character) -> Bool {
+        let closing: Set<Character> = ["，", "。", "！", "？", "；", "：", "、", ",", ".", "!", "?", ";", ":"]
+        return closing.contains(character)
+    }
+
+    private static func isOpeningPunctuation(_ character: Character) -> Bool {
+        let opening: Set<Character> = ["（", "「", "“"]
+        return opening.contains(character)
+    }
+
     private static func extractEmojis(from text: String) -> [String] {
         text.unicodeScalars.filter(isEmojiScalar).map { String($0) }
     }
diff --git a/OSGKeyboardShared/en.lproj/Shared.strings b/OSGKeyboardShared/en.lproj/Shared.strings
index 66d0528..4cdeddd 100644
--- a/OSGKeyboardShared/en.lproj/Shared.strings
+++ b/OSGKeyboardShared/en.lproj/Shared.strings
@@ -7,6 +7,7 @@
 /* v0.2.0: flow-level warnings surfaced alongside the final transcript. */
 "flow.warning.cloudPolishMissingKey" = "Cloud polish needs an API key in Settings. Inserted raw ASR text.";
 "flow.warning.localPolishUnavailable" = "Built-in polish is unavailable. Inserted raw ASR text.";
+"flow.warning.polishDegraded" = "Weak network — inserted raw ASR text without polish.";
 
 /* LLM providers */
 "provider.openai" = "OpenAI";
diff --git a/OSGKeyboardShared/zh-Hans.lproj/Shared.strings b/OSGKeyboardShared/zh-Hans.lproj/Shared.strings
index a1faf86..32b9cf3 100644
--- a/OSGKeyboardShared/zh-Hans.lproj/Shared.strings
+++ b/OSGKeyboardShared/zh-Hans.lproj/Shared.strings
@@ -7,6 +7,7 @@
 /* v0.2.0: flow-level warnings surfaced alongside the final transcript. */
 "flow.warning.cloudPolishMissingKey" = "云端润色需要先在设置中填写 API Key，本次已插入原始识别结果。";
 "flow.warning.localPolishUnavailable" = "内置润色暂不可用，本次已插入原始识别结果。";
+"flow.warning.polishDegraded" = "弱网识别，本次未润色，已插入原始识别结果。";
 
 /* LLM providers */
 "provider.openai" = "OpenAI";
diff --git a/OSGKeyboardTests/FakeUbiquitousKeyValueStore.swift b/OSGKeyboardTests/FakeUbiquitousKeyValueStore.swift
new file mode 100644
index 0000000..37bd616
--- /dev/null
+++ b/OSGKeyboardTests/FakeUbiquitousKeyValueStore.swift
@@ -0,0 +1,37 @@
+// FakeUbiquitousKeyValueStore.swift
+// OSGKeyboardTests
+//
+// In-memory KVS fake for hermetic iCloud sync tests.
+
+import Foundation
+@testable import OSGKeyboardShared
+
+final class FakeUbiquitousKeyValueStore: UbiquitousKeyValueStoreing, @unchecked Sendable {
+    private var storage: [String: Any] = [:]
+
+    func data(forKey key: String) -> Data? {
+        storage[key] as? Data
+    }
+
+    func set(_ value: Data?, forKey key: String) {
+        if let value {
+            storage[key] = value
+        } else {
+            storage.removeValue(forKey: key)
+        }
+    }
+
+    func object(forKey key: String) -> Any? {
+        storage[key]
+    }
+
+    func set(_ value: Any?, forKey key: String) {
+        if let value {
+            storage[key] = value
+        } else {
+            storage.removeValue(forKey: key)
+        }
+    }
+
+    func synchronize() -> Bool { true }
+}
diff --git a/OSGKeyboardTests/FlowSessionBridgeTests.swift b/OSGKeyboardTests/FlowSessionBridgeTests.swift
index b544cfd..eae94bd 100644
--- a/OSGKeyboardTests/FlowSessionBridgeTests.swift
+++ b/OSGKeyboardTests/FlowSessionBridgeTests.swift
@@ -23,6 +23,40 @@ final class FlowSessionBridgeTests: XCTestCase {
         defaults.set(staleHeartbeat, forKey: FlowSessionKeys.flowHeartbeat)
         XCTAssertTrue(FlowSessionBridge.isSessionActive(defaults: defaults))
         XCTAssertFalse(FlowSessionBridge.isHostReachable(defaults: defaults))
+        XCTAssertFalse(FlowSessionBridge.isHostStale(defaults: defaults))
+    }
+
+    func testHostStaleWhenHeartbeatVeryOld() {
+        let defaults = makeDefaults()
+        FlowSessionBridge.markSessionActive(duration: 3_600, defaults: defaults)
+        let zombieHeartbeat = Date().timeIntervalSince1970 - 120
+        defaults.set(zombieHeartbeat, forKey: FlowSessionKeys.flowHeartbeat)
+
+        XCTAssertTrue(FlowSessionBridge.isSessionActive(defaults: defaults))
+        XCTAssertFalse(FlowSessionBridge.isHostReachable(defaults: defaults))
+        XCTAssertTrue(FlowSessionBridge.isHostStale(defaults: defaults))
+    }
+
+    func testClearIfHostStaleRemovesZombieSession() {
+        let defaults = makeDefaults()
+        FlowSessionBridge.markSessionActive(duration: 3_600, defaults: defaults)
+        FlowSessionBridge.setRecordingState(.stopped, defaults: defaults)
+        let zombieHeartbeat = Date().timeIntervalSince1970 - 120
+        defaults.set(zombieHeartbeat, forKey: FlowSessionKeys.flowHeartbeat)
+
+        XCTAssertTrue(FlowSessionBridge.clearIfHostStale(defaults: defaults))
+        XCTAssertFalse(FlowSessionBridge.isSessionActive(defaults: defaults))
+        XCTAssertEqual(FlowSessionBridge.recordingState(defaults: defaults), .idle)
+    }
+
+    func testHostStaleWhenSessionActiveButNoHeartbeat() {
+        let defaults = makeDefaults()
+        defaults.set(true, forKey: FlowSessionKeys.flowSessionActive)
+        defaults.set(Date().timeIntervalSince1970 + 3_600, forKey: FlowSessionKeys.flowSessionExpires)
+
+        XCTAssertTrue(FlowSessionBridge.isHostStale(defaults: defaults))
+        XCTAssertTrue(FlowSessionBridge.clearIfHostStale(defaults: defaults))
+        XCTAssertFalse(FlowSessionBridge.isSessionActive(defaults: defaults))
     }
 
     func testSessionInactiveWhenExpired() {
diff --git a/OSGKeyboardTests/IntelligentPolishTests.swift b/OSGKeyboardTests/IntelligentPolishTests.swift
index 0ee0720..9f62a3e 100644
--- a/OSGKeyboardTests/IntelligentPolishTests.swift
+++ b/OSGKeyboardTests/IntelligentPolishTests.swift
@@ -326,6 +326,32 @@ final class IntelligentPolishTests: XCTestCase {
         XCTAssertEqual(output, "this is a broken sentence")
     }
 
+    func testCleanRawASRFallbackRemovesChineseInteriorSpaces() {
+        let input = "  你 是不是 已经 解决了 这个 问题 ？  "
+        let output = TranscriptPostProcessor.cleanRawASRFallback(input)
+        XCTAssertEqual(output, "你是不是已经解决了这个问题？")
+    }
+
+    func testCleanRawASRFallbackPreservesEnglishAndMixedSpaces() {
+        let input = "iOS 版本 uses Swift UI"
+        let output = TranscriptPostProcessor.cleanRawASRFallback(input)
+        XCTAssertEqual(output, "iOS 版本 uses Swift UI")
+    }
+
+    @MainActor
+    func testFlowFallbackDeliveryCleansTextAndCarriesWeakNetworkWarning() {
+        let delivery = FlowSessionManager.makeFallbackDelivery(
+            rawText: "  你 是不是 已经 解决了 这个 问题 ？  ",
+            error: LLMError.transport("offline"),
+            engineMode: "cloud",
+            chunkWarning: nil
+        )
+
+        XCTAssertEqual(delivery.text, "你是不是已经解决了这个问题？")
+        XCTAssertFalse(delivery.text.contains("未润色"))
+        XCTAssertEqual(delivery.polishWarning, SharedL10n.string("flow.warning.polishDegraded"))
+    }
+
     func testHasStructureSignalDetectsChineseEnumeration() {
         XCTAssertTrue(TranscriptPostProcessor.hasStructureSignal(in: "首先测试其次上线"))
         XCTAssertTrue(TranscriptPostProcessor.hasStructureSignal(in: "第一点修复"))
diff --git a/OSGKeyboardTests/PersonalDictionaryCloudSyncTests.swift b/OSGKeyboardTests/PersonalDictionaryCloudSyncTests.swift
index b09fc2e..e6534dc 100644
--- a/OSGKeyboardTests/PersonalDictionaryCloudSyncTests.swift
+++ b/OSGKeyboardTests/PersonalDictionaryCloudSyncTests.swift
@@ -8,23 +8,7 @@ import XCTest
 
 // MARK: - Fake KVS
 
-private final class FakeUbiquitousKeyValueStore: UbiquitousKeyValueStoreing, @unchecked Sendable {
-    private var storage: [String: Data] = [:]
-
-    func data(forKey key: String) -> Data? {
-        storage[key]
-    }
-
-    func set(_ value: Data?, forKey key: String) {
-        if let value {
-            storage[key] = value
-        } else {
-            storage.removeValue(forKey: key)
-        }
-    }
-
-    func synchronize() -> Bool { true }
-}
+// See FakeUbiquitousKeyValueStore.swift
 
 // MARK: - Tests
 
@@ -170,6 +154,7 @@ final class PersonalDictionaryCloudSyncTests: XCTestCase {
         try await sync.enableSync()
 
         XCTAssertTrue(store.personalDictionaryICloudSyncEnabled)
+        XCTAssertEqual(kvs.object(forKey: ICloudSyncPreferences.dictionaryEnabledKey) as? Bool, true)
         XCTAssertEqual(Set(store.personalDictionary.entries.map(\.term)), Set(["LocalTerm", "RemoteTerm"]))
         XCTAssertNotNil(sync.loadRemote())
     }
diff --git a/OSGKeyboardTests/SettingsCloudSyncTests.swift b/OSGKeyboardTests/SettingsCloudSyncTests.swift
new file mode 100644
index 0000000..3b3c836
--- /dev/null
+++ b/OSGKeyboardTests/SettingsCloudSyncTests.swift
@@ -0,0 +1,157 @@
+// SettingsCloudSyncTests.swift
+// OSGKeyboardTests
+//
+// Hermetic tests for iCloud KVS settings sync + preference toggles.
+
+import XCTest
+@testable import OSGKeyboardShared
+
+@MainActor
+final class SettingsCloudSyncTests: XCTestCase {
+
+    private var suiteName: String!
+    private var defaults: UserDefaults!
+    private var store: AppGroupStore!
+    private var kvs: FakeUbiquitousKeyValueStore!
+    private var settingsSync: SettingsCloudSync!
+
+    override func setUp() {
+        super.setUp()
+        suiteName = "group.com.osgkeyboard.shared.tests.settings.\(UUID().uuidString)"
+        defaults = UserDefaults(suiteName: suiteName)!
+        defaults.removePersistentDomain(forName: suiteName)
+        store = AppGroupStore(defaults: defaults)
+        kvs = FakeUbiquitousKeyValueStore()
+        settingsSync = SettingsCloudSync(kvs: kvs) { [unowned self] in store }
+    }
+
+    override func tearDown() {
+        defaults.removePersistentDomain(forName: suiteName)
+        super.tearDown()
+    }
+
+    func testMergePrefersNewerUpdatedAt() {
+        let older = SyncedAppSettings(
+            updatedAt: Date(timeIntervalSince1970: 100),
+            providerId: "openai",
+            baseURL: "https://old.example",
+            model: "gpt-old",
+            modeId: "polish",
+            localeId: "auto",
+            engineMode: "cloud",
+            hasAcknowledgedCloudSharing: false,
+            uiLanguage: .english,
+            translationTargetLocaleId: TranslationLanguageCatalog.offLocaleId,
+            handednessPreference: .left,
+            cursorDragNavigationEnabled: true,
+            polishIntensity: .medium,
+            flowSkipAppSwitch: true,
+            flowInactivityDuration: .twelveHours
+        )
+        let newer = SyncedAppSettings(
+            updatedAt: Date(timeIntervalSince1970: 200),
+            providerId: "openai",
+            baseURL: "https://new.example",
+            model: "gpt-new",
+            modeId: "polish",
+            localeId: "zh-Hans",
+            engineMode: "local",
+            hasAcknowledgedCloudSharing: true,
+            uiLanguage: .chinese,
+            translationTargetLocaleId: "en",
+            handednessPreference: .right,
+            cursorDragNavigationEnabled: false,
+            polishIntensity: .light,
+            flowSkipAppSwitch: false,
+            flowInactivityDuration: .threeHours
+        )
+
+        let merged = SyncedAppSettings.merge(local: older, remote: newer)
+        XCTAssertEqual(merged.model, "gpt-new")
+        XCTAssertEqual(merged.localeId, "zh-Hans")
+        XCTAssertEqual(merged.engineMode, "local")
+    }
+
+    func testEnableSyncUploadsMergedSettingsAndToggle() async throws {
+        store.setModeId("polish")
+        store.setLocaleId("zh-Hans")
+
+        let remote = SyncedAppSettings(
+            updatedAt: Date().addingTimeInterval(3600),
+            providerId: "openai",
+            baseURL: "https://remote.example",
+            model: "remote-model",
+            modeId: "polish",
+            localeId: "en",
+            engineMode: "cloud",
+            hasAcknowledgedCloudSharing: true,
+            uiLanguage: .english,
+            translationTargetLocaleId: TranslationLanguageCatalog.offLocaleId,
+            handednessPreference: .right,
+            cursorDragNavigationEnabled: true,
+            polishIntensity: .medium,
+            flowSkipAppSwitch: true,
+            flowInactivityDuration: .twelveHours
+        )
+        try settingsSync.push(remote)
+
+        try await settingsSync.enableSync()
+
+        XCTAssertTrue(store.settingsICloudSyncEnabled)
+        XCTAssertEqual(kvs.object(forKey: ICloudSyncPreferences.settingsEnabledKey) as? Bool, true)
+        XCTAssertEqual(settingsSync.loadRemote()?.localeId, "en")
+    }
+
+    func testPullAndMergeAppliesRemoteSettingsToAppGroup() async throws {
+        store.setSettingsICloudSyncEnabled(true)
+        store.setLocaleId("auto")
+
+        let remote = SyncedAppSettings(
+            updatedAt: Date(timeIntervalSince1970: 900),
+            providerId: "openai",
+            baseURL: "https://remote.example",
+            model: "remote-model",
+            modeId: "polish",
+            localeId: "ja",
+            engineMode: "cloud",
+            hasAcknowledgedCloudSharing: false,
+            uiLanguage: .english,
+            translationTargetLocaleId: TranslationLanguageCatalog.offLocaleId,
+            handednessPreference: .left,
+            cursorDragNavigationEnabled: true,
+            polishIntensity: .medium,
+            flowSkipAppSwitch: true,
+            flowInactivityDuration: .twelveHours
+        )
+        try settingsSync.push(remote)
+
+        await settingsSync.pullAndMerge(store: store)
+
+        XCTAssertEqual(store.localeId, "ja")
+        XCTAssertEqual(store.settingsCloudUpdatedAt?.timeIntervalSince1970, 900, accuracy: 1)
+    }
+
+    func testPushLocalIfEnabledSkipsWhenDisabled() async throws {
+        store.setSettingsICloudSyncEnabled(false)
+        store.setLocaleId("ko")
+
+        try await settingsSync.pushLocalIfEnabled()
+
+        XCTAssertNil(settingsSync.loadRemote())
+    }
+
+    func testICloudSyncPreferencesMigrateLegacyToggles() {
+        store.setSettingsICloudSyncEnabled(false)
+        store.setPersonalDictionaryICloudSyncEnabled(true)
+
+        ICloudSyncPreferences.migrateLegacyTogglesIfNeeded(kvs: kvs, store: store)
+
+        XCTAssertEqual(kvs.object(forKey: ICloudSyncPreferences.settingsEnabledKey) as? Bool, false)
+        XCTAssertEqual(kvs.object(forKey: ICloudSyncPreferences.dictionaryEnabledKey) as? Bool, true)
+    }
+
+    func testAppGroupConfigurationDefaultsSettingsICloudSyncToOn() {
+        let config = AppGroupConfiguration.load(fromAvailable: defaults)
+        XCTAssertTrue(config.settingsICloudSyncEnabled)
+    }
+}
diff --git a/project.yml b/project.yml
index 3ce7a6e..383520f 100644
--- a/project.yml
+++ b/project.yml
@@ -35,9 +35,15 @@ settings:
     SWIFT_STRICT_CONCURRENCY: complete
     GENERATE_INFOPLIST_FILE: NO
     ENABLE_MODULE_VERIFIER: YES
+    MODULE_VERIFIER_SUPPORTED_LANGUAGES: "objective-c objective-c++"
+    MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS: "gnu17 gnu++17"
+    CLANG_ANALYZER_LOCALIZABILITY_NONLOCALIZED: YES
+    ASSETCATALOG_COMPILER_GENERATE_ASSET_SYMBOLS: YES
+    ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS: YES
+    STRING_CATALOG_GENERATE_SYMBOLS: YES
     CLANG_CXX_LANGUAGE_STANDARD: c++17
-    MARKETING_VERSION: "0.4.1"
-    CURRENT_PROJECT_VERSION: "17"
+    MARKETING_VERSION: "0.5.0"
+    CURRENT_PROJECT_VERSION: "18"
     # 签名配置来自 Signing.local.xcconfig（gitignored，不会被覆盖）
 
 # 项目级签名 xcconfig，适用于所有 target
@@ -325,10 +331,12 @@ targets:
         DYLIB_INSTALL_NAME_BASE: "@rpath"
         APPLICATION_EXTENSION_API_ONLY: YES
         ENABLE_MODULE_VERIFIER: YES
-        # Frameworks inherit the host app's signing identity; no profile
-        # is required, but pinning the team keeps the build reproducible.
-        CODE_SIGN_STYLE: Automatic
-        DEVELOPMENT_TEAM: X329MZU23S
+        # Embedded frameworks are re-signed by the containing app at package
+        # time. Signing this framework as a standalone build product is noisy
+        # and not recommended by Xcode.
+        CODE_SIGNING_ALLOWED: NO
+        CODE_SIGNING_REQUIRED: NO
+        CODE_SIGN_IDENTITY: ""
     dependencies:
       - sdk: Speech.framework
       - sdk: AVFoundation.framework