feat(home): add usage statistics card above preview field

Track dictation duration, dictation/translation character counts, and
personal dictionary size. Record metrics when Flow finalizes utterances.

Co-authored-by: Rocky <hkgood@users.noreply.github.com>

OSGKeyboard/Services/FlowSessionManager.swift

@@ -57,6 +57,8 @@ final class FlowSessionManager: ObservableObject {
     private var currentPartial = ""
     private var lastFinal = ""
     private var chunkWarnings: [String] = []
+    /// Wall-clock span of the current mic-open utterance (excludes LLM polish).
+    private var utteranceRecordingStartedAt: Date?
     /// True while the host app scene is `.active` — drives foreground renewal.
     private var isAppForeground = false
     private var backgroundTaskID: UIBackgroundTaskIdentifier = .invalid
@@ -407,6 +409,7 @@ final class FlowSessionManager: ObservableObject {
         chunkedPipeline = pipeline
 
         isUtteranceRecording = true
+        utteranceRecordingStartedAt = Date()
         FlowDiagnostics.log(
             "beginUtterance engine=\(store.engineMode) asr=\(store.localASRBackend.rawValue) " +
             "asrType=\(type(of: asr)) pipelined=true max=\(Int(FlowSessionKeys.maxUtteranceDuration))s"
@@ -473,6 +476,7 @@ final class FlowSessionManager: ObservableObject {
     private func abortUtterance() {
         isUtteranceRecording = false
         isUtteranceProcessing = false
+        utteranceRecordingStartedAt = nil
         finalizeTask?.cancel()
         finalizeTask = nil
         asrTask?.cancel()
@@ -490,6 +494,7 @@ final class FlowSessionManager: ObservableObject {
     private func failUtterance(message: String) {
         isUtteranceRecording = false
         isUtteranceProcessing = false
+        utteranceRecordingStartedAt = nil
         finalizeTask?.cancel()
         finalizeTask = nil
         asrTask?.cancel()
@@ -507,6 +512,7 @@ final class FlowSessionManager: ObservableObject {
 
     private func finishProcessing(withError message: String) {
         isUtteranceProcessing = false
+        utteranceRecordingStartedAt = nil
         finalizeTask?.cancel()
         finalizeTask = nil
         chunkedPipeline = nil
@@ -555,12 +561,15 @@ final class FlowSessionManager: ObservableObject {
                 ? "flow.error.recognitionInterrupted"
                 : "flow.error.noSpeech"
             FlowDiagnostics.log("finalize failed: empty transcript after \(String(format: "%.1f", asrElapsed))s")
+            utteranceRecordingStartedAt = nil
             FlowSessionBridge.storeTranscriptionError(
                 AppL10n.string(key)
             )
             return
         }
 
+        let recordingDuration = consumeRecordingDuration()
+
         let engineMode = store.engineMode
         let chunkNote = Self.chunkWarningMessage(chunkWarnings)
         // Re-read App Group at finalize so chip-side translation changes
@@ -574,7 +583,12 @@ final class FlowSessionManager: ObservableObject {
                 "finalize ASR-only total=\(String(format: "%.1f", Date().timeIntervalSince(pipelineStarted)))s " +
                 "len=\(text.count)"
             )
-            SpeechHistoryStore.shared.append(text: text, engineMode: engineMode)
+            SpeechHistoryStore.shared.recordUtterance(
+                text: text,
+                engineMode: engineMode,
+                duration: recordingDuration,
+                wasTranslation: false
+            )
             currentPartial = ""
             lastFinal = ""
             chunkWarnings = []
@@ -616,7 +630,12 @@ final class FlowSessionManager: ObservableObject {
             FlowSessionBridge.storeTranscriptionResult(text, polishWarning: warning)
         }
 
-        SpeechHistoryStore.shared.append(text: delivered, engineMode: engineMode)
+        SpeechHistoryStore.shared.recordUtterance(
+            text: delivered,
+            engineMode: engineMode,
+            duration: recordingDuration,
+            wasTranslation: pipelineStore.isTranslationEffective
+        )
 
         currentPartial = ""
         lastFinal = ""
@@ -639,6 +658,12 @@ final class FlowSessionManager: ObservableObject {
         return warnings.joined(separator: "\n")
     }
 
+    private func consumeRecordingDuration() -> TimeInterval {
+        defer { utteranceRecordingStartedAt = nil }
+        guard let start = utteranceRecordingStartedAt else { return 0 }
+        return max(0, Date().timeIntervalSince(start))
+    }
+
     /// 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.

OSGKeyboard/Services/SpeechHistoryStore.swift

@@ -47,6 +47,21 @@ final class SpeechHistoryStore: ObservableObject {
         persist()
     }
 
+    /// Append history and update cumulative home-screen usage stats.
+    func recordUtterance(
+        text: String,
+        engineMode: String,
+        duration: TimeInterval,
+        wasTranslation: Bool
+    ) {
+        append(text: text, engineMode: engineMode)
+        UsageStatisticsStore.shared.recordUtterance(
+            text: text,
+            duration: duration,
+            wasTranslation: wasTranslation
+        )
+    }
+
     func clearAll() {
         entries.removeAll()
         persist()

OSGKeyboard/Services/UsageStatisticsStore.swift

@@ -0,0 +1,102 @@
+// UsageStatisticsStore.swift
+// OSGKeyboard · Main App
+//
+// Cumulative usage metrics shown on the home screen stats card.
+// Updated when Flow finalizes a successful utterance.
+
+import Foundation
+import Combine
+
+struct UsageStatistics: Codable, Equatable {
+    var dictationDurationSeconds: TimeInterval
+    var dictationCharacterCount: Int
+    var translationCharacterCount: Int
+
+    static let zero = UsageStatistics(
+        dictationDurationSeconds: 0,
+        dictationCharacterCount: 0,
+        translationCharacterCount: 0
+    )
+}
+
+@MainActor
+final class UsageStatisticsStore: ObservableObject {
+    static let shared = UsageStatisticsStore()
+
+    @Published private(set) var dictationDurationSeconds: TimeInterval = 0
+    @Published private(set) var dictationCharacterCount: Int = 0
+    @Published private(set) var translationCharacterCount: Int = 0
+
+    private let defaults: UserDefaults
+    private let storageKey = "usageStatistics.v1"
+
+    init(defaults: UserDefaults = .standard) {
+        self.defaults = defaults
+        load()
+    }
+
+    func recordUtterance(text: String, duration: TimeInterval, wasTranslation: Bool) {
+        let trimmed = text.trimmingCharacters(in: .whitespacesAndNewlines)
+        guard !trimmed.isEmpty else { return }
+
+        let count = Self.characterCount(for: trimmed)
+        if wasTranslation {
+            translationCharacterCount += count
+        } else {
+            dictationCharacterCount += count
+        }
+        dictationDurationSeconds += max(0, duration)
+        persist()
+    }
+
+    static func characterCount(for text: String) -> Int {
+        text.trimmingCharacters(in: .whitespacesAndNewlines).count
+    }
+
+    // MARK: - Formatting
+
+    static func formatDuration(_ seconds: TimeInterval, language: AppUILanguage) -> String {
+        let total = max(0, Int(seconds.rounded()))
+        if total < 60 {
+            return language.resolvedLanguageCode().hasPrefix("zh")
+                ? "\(total)秒"
+                : "\(total)s"
+        }
+        let hours = total / 3600
+        let minutes = (total % 3600) / 60
+        if hours > 0 {
+            return language.resolvedLanguageCode().hasPrefix("zh")
+                ? "\(hours)小时\(minutes)分"
+                : "\(hours)h \(minutes)m"
+        }
+        return language.resolvedLanguageCode().hasPrefix("zh")
+            ? "\(minutes)分"
+            : "\(minutes)m"
+    }
+
+    static func formatCount(_ value: Int, language: AppUILanguage) -> String {
+        let formatter = NumberFormatter()
+        formatter.numberStyle = .decimal
+        formatter.locale = Locale(identifier: language.resolvedLanguageCode())
+        return formatter.string(from: NSNumber(value: value)) ?? "\(value)"
+    }
+
+    private func load() {
+        guard let data = defaults.data(forKey: storageKey),
+              let stats = try? JSONDecoder().decode(UsageStatistics.self, from: data)
+        else { return }
+        dictationDurationSeconds = stats.dictationDurationSeconds
+        dictationCharacterCount = stats.dictationCharacterCount
+        translationCharacterCount = stats.translationCharacterCount
+    }
+
+    private func persist() {
+        let stats = UsageStatistics(
+            dictationDurationSeconds: dictationDurationSeconds,
+            dictationCharacterCount: dictationCharacterCount,
+            translationCharacterCount: translationCharacterCount
+        )
+        guard let data = try? JSONEncoder().encode(stats) else { return }
+        defaults.set(data, forKey: storageKey)
+    }
+}

OSGKeyboard/Views/Components/HomeStatsCard.swift

@@ -0,0 +1,132 @@
+// HomeStatsCard.swift
+// OSGKeyboard · Main App
+//
+// Home screen summary: dictation time, dictation characters,
+// translation characters, and personal-dictionary entry count.
+
+import SwiftUI
+import OSGKeyboardShared
+
+struct HomeStatsCard: View {
+    @Environment(\.themePalette) private var palette: ThemePalette
+
+    @ObservedObject private var stats = UsageStatisticsStore.shared
+    @ObservedObject private var config = ProviderConfig.shared
+
+    @State private var dictionaryCount = 0
+
+    var body: some View {
+        VStack(spacing: 0) {
+            HStack(spacing: 0) {
+                statCell(
+                    systemImage: "waveform",
+                    value: UsageStatisticsStore.formatDuration(
+                        stats.dictationDurationSeconds,
+                        language: config.uiLanguage
+                    ),
+                    label: "home.stats.dictationDuration"
+                )
+                divider
+                statCell(
+                    systemImage: "text.alignleft",
+                    value: UsageStatisticsStore.formatCount(
+                        stats.dictationCharacterCount,
+                        language: config.uiLanguage
+                    ),
+                    label: "home.stats.dictationCharacters"
+                )
+            }
+            horizontalDivider
+            HStack(spacing: 0) {
+                statCell(
+                    systemImage: "character.bubble",
+                    value: UsageStatisticsStore.formatCount(
+                        stats.translationCharacterCount,
+                        language: config.uiLanguage
+                    ),
+                    label: "home.stats.translationCharacters"
+                )
+                divider
+                statCell(
+                    systemImage: "books.vertical",
+                    value: UsageStatisticsStore.formatCount(
+                        dictionaryCount,
+                        language: config.uiLanguage
+                    ),
+                    label: "home.stats.dictionaryEntries"
+                )
+            }
+        }
+        .background(cardBackground, in: RoundedRectangle(cornerRadius: Radius.xl, style: .continuous))
+        .overlay(
+            RoundedRectangle(cornerRadius: Radius.xl, style: .continuous)
+                .stroke(palette.divider, lineWidth: 0.5)
+        )
+        .onAppear(perform: refreshDictionaryCount)
+        .onReceive(NotificationCenter.default.publisher(for: UIApplication.didBecomeActiveNotification)) { _ in
+            refreshDictionaryCount()
+        }
+    }
+
+    private var cardBackground: some View {
+        ZStack(alignment: .top) {
+            palette.surface
+            LinearGradient(
+                colors: [
+                    palette.accent.opacity(0.10),
+                    palette.accent.opacity(0.02),
+                    palette.surface.opacity(0)
+                ],
+                startPoint: .topLeading,
+                endPoint: .bottomTrailing
+            )
+        }
+    }
+
+    private func statCell(systemImage: String, value: String, label: LocalizedStringKey) -> some View {
+        VStack(alignment: .leading, spacing: Spacing.xs) {
+            HStack(spacing: 6) {
+                Image(systemName: systemImage)
+                    .font(.system(size: 13, weight: .semibold))
+                    .foregroundStyle(palette.accent)
+                Text(value)
+                    .font(TypeStyle.headline)
+                    .foregroundStyle(palette.textPrimary)
+                    .lineLimit(1)
+                    .minimumScaleFactor(0.75)
+            }
+            Text(label)
+                .font(TypeStyle.caption2)
+                .foregroundStyle(palette.textSecondary)
+                .lineLimit(1)
+                .minimumScaleFactor(0.85)
+        }
+        .frame(maxWidth: .infinity, alignment: .leading)
+        .padding(Spacing.md)
+    }
+
+    private var divider: some View {
+        Rectangle()
+            .fill(palette.divider)
+            .frame(width: 0.5)
+    }
+
+    private var horizontalDivider: some View {
+        Rectangle()
+            .fill(palette.divider)
+            .frame(height: 0.5)
+    }
+
+    private func refreshDictionaryCount() {
+        dictionaryCount = AppGroupStore().personalDictionary.entries.count
+    }
+}
+
+#if DEBUG
+#Preview {
+    ThemedRoot {
+        HomeStatsCard()
+            .padding()
+    }
+}
+#endif

OSGKeyboard/Views/HomeView.swift

@@ -64,6 +64,10 @@ struct HomeView: View {
                             .padding(.bottom, Spacing.lg)
                     }
 
+                    HomeStatsCard()
+                        .padding(.horizontal, Spacing.lg)
+                        .padding(.bottom, Spacing.md)
+
                     previewField
                         .padding(.horizontal, Spacing.lg)
                         .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .top)

OSGKeyboard/en.lproj/Localizable.strings

@@ -292,6 +292,10 @@
 "home.flow.endShort" = "End";
 "home.preview.label" = "Try typing";
 "home.preview.placeholder" = "Tap to type and test…";
+"home.stats.dictationDuration" = "Dictation time";
+"home.stats.dictationCharacters" = "Dictation chars";
+"home.stats.translationCharacters" = "Translation chars";
+"home.stats.dictionaryEntries" = "Dictionary";
 "home.engine.unsupportedOS" = "Qwen3-ASR CoreML requires iOS 18+";
 "home.engine.warming" = "Loading ASR model into memory…";
 "home.engine.downloading" = "Downloading ASR model…";

OSGKeyboard/zh-Hans.lproj/Localizable.strings

@@ -291,6 +291,10 @@
 "home.flow.endShort" = "结束";
 "home.preview.label" = "输入测试";
 "home.preview.placeholder" = "点这里试试键盘";
+"home.stats.dictationDuration" = "听写时长";
+"home.stats.dictationCharacters" = "听写字数";
+"home.stats.translationCharacters" = "翻译字数";
+"home.stats.dictionaryEntries" = "个性词库";
 "home.engine.unsupportedOS" = "Qwen3-ASR CoreML 需要 iOS 18 或更高版本";
 "home.engine.warming" = "正在加载语音识别模型…";
 "home.engine.downloading" = "正在下载语音识别模型…";