diff --git a/android/oral-trainer-sdk/src/main/java/cn/learningpad/oraltrainer/sdk/OralTrainerController.kt b/android/oral-trainer-sdk/src/main/java/cn/learningpad/oraltrainer/sdk/OralTrainerController.kt
index bfb20f3..57d9fb5 100644
--- a/android/oral-trainer-sdk/src/main/java/cn/learningpad/oraltrainer/sdk/OralTrainerController.kt
+++ b/android/oral-trainer-sdk/src/main/java/cn/learningpad/oraltrainer/sdk/OralTrainerController.kt
@@ -258,9 +258,14 @@ class OralTrainerController internal constructor(
 
     fun playCurrentSentenceAndStop() {
         val sentence = currentSentence() ?: return
-        player.seekTo(sentence.startMs)
+        playSentenceAndStop(sentence.startMs, sentence.index)
+    }
+
+    /** Seek to a known sentence and stop automatically when that sentence ends. */
+    fun playSentenceAndStop(startMs: Long, sentenceIndex: Int) {
         stopAtSentenceEnd = true
-        stopAtSentenceEndIndex = sentence.index
+        stopAtSentenceEndIndex = sentenceIndex
+        player.seekTo(max(0L, startMs))
         player.play()
         refreshSentenceBoundaryGuard()
     }
diff --git a/android/oral-trainer-sdk/src/main/java/cn/learningpad/oraltrainer/sdk/UserApi.kt b/android/oral-trainer-sdk/src/main/java/cn/learningpad/oraltrainer/sdk/UserApi.kt
index d6841fc..9694645 100644
--- a/android/oral-trainer-sdk/src/main/java/cn/learningpad/oraltrainer/sdk/UserApi.kt
+++ b/android/oral-trainer-sdk/src/main/java/cn/learningpad/oraltrainer/sdk/UserApi.kt
@@ -67,6 +67,21 @@ data class UserDubShare(
     val createdAt: String,
 )
 
+data class DubShareSegmentDetail(
+    val index: Int,
+    val overallScore: Float,
+    val recognizedText: String,
+    val scoreDetails: Map<String, Float>,
+    val audioUrl: String,
+)
+
+data class DubShareDetail(
+    val shareId: String,
+    val videoHash: String,
+    val title: String,
+    val segments: List<DubShareSegmentDetail>,
+)
+
 class UserApiException(
     val statusCode: Int,
     responseBody: String,
@@ -150,6 +165,13 @@ class UserApi internal constructor(
         onComplete: (Result<List<UserDubShare>>) -> Unit,
     ): CancellableRequest = submitObject(onComplete, token) { parseDubShares(getBlocking(it, "api/v1/me/dub-shares")) }
 
+    fun dubShareDetail(
+        shareId: String,
+        onComplete: (Result<DubShareDetail>) -> Unit,
+    ): CancellableRequest = submit(onComplete) {
+        parseDubShareDetail(JSONObject(request("api/v1/dub-shares/$shareId", method = "GET")))
+    }
+
     fun release() {
         executor.shutdownNow()
     }
@@ -252,6 +274,34 @@ class UserApi internal constructor(
         )
     }
 
+    private fun parseDubShareDetail(root: JSONObject): DubShareDetail {
+        val segmentsJson = root.optJSONArray("segments") ?: JSONArray()
+        val segments = List(segmentsJson.length()) { index ->
+            val item = segmentsJson.getJSONObject(index)
+            val detailsJson = item.optJSONObject("score_details") ?: JSONObject()
+            val scoreDetails = buildMap<String, Float> {
+                for (key in detailsJson.keys()) {
+                    if (!detailsJson.isNull(key)) {
+                        put(key, detailsJson.optDouble(key).toFloat())
+                    }
+                }
+            }
+            DubShareSegmentDetail(
+                index = item.getInt("index"),
+                overallScore = item.optDouble("overall_score", 0.0).toFloat(),
+                recognizedText = item.optString("recognized_text"),
+                scoreDetails = scoreDetails,
+                audioUrl = item.getString("audio_url"),
+            )
+        }
+        return DubShareDetail(
+            shareId = root.getString("share_id"),
+            videoHash = root.getString("video_hash"),
+            title = root.optString("title"),
+            segments = segments,
+        )
+    }
+
     private fun request(
         path: String,
         token: String? = null,
diff --git a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/AssessmentState.kt b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/AssessmentState.kt
index dcd453c..1fe5788 100644
--- a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/AssessmentState.kt
+++ b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/AssessmentState.kt
@@ -9,5 +9,19 @@ internal class AssessmentState {
         scores[sentenceIndex] = result
     }
 
+    fun get(sentenceIndex: Int): ImitationAssessmentResult? = scores[sentenceIndex]
+
+    fun replaceAll(values: Map<Int, ImitationAssessmentResult>) {
+        scores.clear()
+        scores.putAll(values)
+    }
+
+    fun clear() {
+        scores.clear()
+    }
+
     fun toMap(): Map<Int, ImitationAssessmentResult> = scores.toMap()
+
+    val size: Int
+        get() = scores.size
 }
diff --git a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingHistoryStore.kt b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingHistoryStore.kt
new file mode 100644
index 0000000..03fcea4
--- /dev/null
+++ b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingHistoryStore.kt
@@ -0,0 +1,244 @@
+package cn.learningpad.oraltrainer.sample
+
+import android.content.Context
+import cn.learningpad.oraltrainer.sdk.ImitationAssessmentResult
+import java.io.File
+import java.net.HttpURLConnection
+import java.net.URL
+import java.util.Locale
+import org.json.JSONArray
+import org.json.JSONObject
+
+/** Persists per-course dubbing audio and assessment scores under app filesDir. */
+internal class DubbingHistoryStore(context: Context) {
+    private val rootDir = File(context.applicationContext.filesDir, "dubbing-history")
+
+    fun loadSnapshot(videoHash: String): Snapshot {
+        val normalized = normalize(videoHash) ?: return Snapshot()
+        val dir = videoDir(normalized)
+        if (!dir.isDirectory) {
+            return Snapshot()
+        }
+        val segments = dir.listFiles()
+            ?.mapNotNull { file ->
+                val match = SEGMENT_PATTERN.matchEntire(file.name) ?: return@mapNotNull null
+                if (!file.isFile || file.length() <= 0L) return@mapNotNull null
+                match.groupValues[1].toInt() to file
+            }
+            ?.toMap()
+            .orEmpty()
+        val merged = File(dir, MERGED_FILE_NAME).takeIf { it.isFile && it.length() > 0L }
+        val scores = readScores(File(dir, SCORES_FILE_NAME))
+        return Snapshot(segments = segments, scores = scores, mergedFile = merged)
+    }
+
+    fun saveSegment(videoHash: String, sentenceIndex: Int, source: File): File {
+        val normalized = requireNotNull(normalize(videoHash)) { "invalid video hash" }
+        val dest = File(videoDir(normalized), "segment-$sentenceIndex.m4a")
+        if (source.canonicalFile != dest.canonicalFile) {
+            source.copyTo(dest, overwrite = true)
+        }
+        // Any new recording invalidates the previous merged export.
+        File(videoDir(normalized), MERGED_FILE_NAME).delete()
+        return dest
+    }
+
+    fun saveScores(videoHash: String, scores: Map<Int, ImitationAssessmentResult>) {
+        val normalized = normalize(videoHash) ?: return
+        val file = File(videoDir(normalized), SCORES_FILE_NAME)
+        val root = JSONObject()
+        scores.toSortedMap().forEach { (index, result) ->
+            root.put(index.toString(), encodeScore(result))
+        }
+        file.writeText(root.toString())
+    }
+
+    fun saveMerged(videoHash: String, source: File): File {
+        val normalized = requireNotNull(normalize(videoHash)) { "invalid video hash" }
+        val dest = File(videoDir(normalized), MERGED_FILE_NAME)
+        if (source.canonicalFile != dest.canonicalFile) {
+            source.copyTo(dest, overwrite = true)
+        }
+        return dest
+    }
+
+    fun clear(videoHash: String) {
+        val normalized = normalize(videoHash) ?: return
+        videoDir(normalized).deleteRecursively()
+    }
+
+    /**
+     * Downloads one public share-audio URL into local history.
+     * Returns the saved file, or null when the download fails.
+     */
+    fun downloadSegmentAudio(
+        baseUrl: String,
+        videoHash: String,
+        sentenceIndex: Int,
+        audioUrl: String,
+    ): File? {
+        val normalized = normalize(videoHash) ?: return null
+        val absolute = when {
+            audioUrl.startsWith("http://") || audioUrl.startsWith("https://") -> audioUrl
+            audioUrl.startsWith("/") -> baseUrl.trimEnd('/') + audioUrl
+            else -> baseUrl.trimEnd('/') + "/" + audioUrl
+        }
+        var connection: HttpURLConnection? = null
+        return try {
+            connection = URL(absolute).openConnection() as HttpURLConnection
+            connection.connectTimeout = 15_000
+            connection.readTimeout = 60_000
+            connection.requestMethod = "GET"
+            connection.instanceFollowRedirects = true
+            val code = connection.responseCode
+            if (code !in 200..299) {
+                return null
+            }
+            val dest = File(videoDir(normalized), "segment-$sentenceIndex.m4a")
+            connection.inputStream.use { input ->
+                dest.outputStream().use { output -> input.copyTo(output) }
+            }
+            if (dest.length() <= 0L) {
+                dest.delete()
+                null
+            } else {
+                dest
+            }
+        } catch (_: Throwable) {
+            null
+        } finally {
+            connection?.disconnect()
+        }
+    }
+
+    private fun videoDir(videoHash: String): File =
+        File(rootDir, videoHash).also { it.mkdirs() }
+
+    private fun readScores(file: File): Map<Int, ImitationAssessmentResult> {
+        if (!file.isFile) {
+            return emptyMap()
+        }
+        return runCatching {
+            val root = JSONObject(file.readText())
+            buildMap {
+                for (key in root.keys()) {
+                    val index = key.toIntOrNull() ?: continue
+                    val value = root.optJSONObject(key) ?: continue
+                    put(index, decodeScore(value))
+                }
+            }
+        }.getOrDefault(emptyMap())
+    }
+
+    data class Snapshot(
+        val segments: Map<Int, File> = emptyMap(),
+        val scores: Map<Int, ImitationAssessmentResult> = emptyMap(),
+        val mergedFile: File? = null,
+    )
+
+    companion object {
+        private const val SCORES_FILE_NAME = "scores.json"
+        private const val MERGED_FILE_NAME = "merged.m4a"
+        private val SEGMENT_PATTERN = Regex("""segment-(\d+)\.m4a""")
+
+        fun normalize(videoHash: String): String? {
+            val value = videoHash.trim().lowercase(Locale.US)
+            return value.takeIf { PlaybackFormat.isVideoHash(it) }
+        }
+
+        fun encodeScore(result: ImitationAssessmentResult): JSONObject =
+            JSONObject().apply {
+                put("overall_score", result.overallScore.toDouble())
+                result.pronunciationScore?.let { put("pronunciation_score", it.toDouble()) }
+                result.fluencyScore?.let { put("fluency_score", it.toDouble()) }
+                result.completenessScore?.let { put("completeness_score", it.toDouble()) }
+                result.feedback?.let { put("feedback", it) }
+                if (result.details.isNotEmpty()) {
+                    put(
+                        "details",
+                        JSONObject().also { details ->
+                            result.details.forEach { (key, value) -> details.put(key, value) }
+                        },
+                    )
+                }
+                result.passed?.let { put("passed", it) }
+                result.contentScore?.let { put("content_score", it.toDouble()) }
+                result.durationScore?.let { put("duration_score", it.toDouble()) }
+                result.pauseScore?.let { put("pause_score", it.toDouble()) }
+                result.speechRateScore?.let { put("speech_rate_score", it.toDouble()) }
+                result.durationRatio?.let { put("duration_ratio", it.toDouble()) }
+                result.referenceText?.let { put("reference_text", it) }
+                result.recognizedText?.let { put("recognized_text", it) }
+                if (result.missingTokens.isNotEmpty()) {
+                    put("missing_tokens", JSONArray(result.missingTokens))
+                }
+                if (result.extraTokens.isNotEmpty()) {
+                    put("extra_tokens", JSONArray(result.extraTokens))
+                }
+                if (result.substitutions.isNotEmpty()) {
+                    put(
+                        "substitutions",
+                        JSONArray().also { array ->
+                            result.substitutions.forEach { (expected, actual) ->
+                                array.put(
+                                    JSONObject()
+                                        .put("expected", expected)
+                                        .put("actual", actual),
+                                )
+                            }
+                        },
+                    )
+                }
+            }
+
+        fun decodeScore(root: JSONObject): ImitationAssessmentResult {
+            val substitutions = buildList {
+                val array = root.optJSONArray("substitutions") ?: return@buildList
+                for (index in 0 until array.length()) {
+                    val item = array.optJSONObject(index) ?: continue
+                    add(item.optString("expected") to item.optString("actual"))
+                }
+            }
+            val details = buildMap {
+                val objectValue = root.optJSONObject("details") ?: return@buildMap
+                for (key in objectValue.keys()) {
+                    put(key, objectValue.optString(key))
+                }
+            }
+            return ImitationAssessmentResult(
+                overallScore = root.optDouble("overall_score", 0.0).toFloat(),
+                pronunciationScore = root.optNullableFloat("pronunciation_score"),
+                fluencyScore = root.optNullableFloat("fluency_score"),
+                completenessScore = root.optNullableFloat("completeness_score"),
+                feedback = root.optString("feedback").ifBlank { null },
+                details = details,
+                passed = if (root.has("passed")) root.optBoolean("passed") else null,
+                contentScore = root.optNullableFloat("content_score"),
+                durationScore = root.optNullableFloat("duration_score"),
+                pauseScore = root.optNullableFloat("pause_score"),
+                speechRateScore = root.optNullableFloat("speech_rate_score"),
+                durationRatio = root.optNullableFloat("duration_ratio"),
+                referenceText = root.optString("reference_text").ifBlank { null },
+                recognizedText = root.optString("recognized_text").ifBlank { null },
+                missingTokens = root.optStringList("missing_tokens"),
+                extraTokens = root.optStringList("extra_tokens"),
+                substitutions = substitutions,
+            )
+        }
+
+        private fun JSONObject.optNullableFloat(name: String): Float? {
+            if (!has(name) || isNull(name)) return null
+            return optDouble(name).toFloat()
+        }
+
+        private fun JSONObject.optStringList(name: String): List<String> {
+            val array = optJSONArray(name) ?: return emptyList()
+            return buildList {
+                for (index in 0 until array.length()) {
+                    val value = array.optString(index)
+                    if (value.isNotBlank()) add(value)
+                }
+            }
+        }
+    }
+}
diff --git a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingPlayback.kt b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingPlayback.kt
index 43154b6..8eb7e92 100644
--- a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingPlayback.kt
+++ b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingPlayback.kt
@@ -24,8 +24,8 @@ internal class DubbingPlayback(
     fun start(
         audioFile: File,
         controller: OralTrainerController,
-        syncToSentence: Boolean,
-        sentenceStartMs: Long?,
+        sentenceStartMs: Long,
+        sentenceIndex: Int,
         onComplete: () -> Unit,
     ) {
         listener?.let(player::removeListener)
@@ -45,11 +45,9 @@ internal class DubbingPlayback(
             }
         }.also(player::addListener)
 
-        if (syncToSentence && sentenceStartMs != null) {
-            controller.seekTo(sentenceStartMs)
-        }
+        // Mute original audio and drive the video for this sentence only.
         controller.setVolume(0f)
-        controller.play()
+        controller.playSentenceAndStop(sentenceStartMs, sentenceIndex)
         player.setMediaItem(MediaItem.fromUri(Uri.fromFile(audioFile)))
         player.prepare()
         player.volume = 1f
diff --git a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingShareApi.kt b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingShareApi.kt
index 632c215..b72ddbe 100644
--- a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingShareApi.kt
+++ b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingShareApi.kt
@@ -10,11 +10,13 @@ import org.json.JSONObject
 internal class DubbingShareApi {
     fun upload(
         baseUrl: String,
+        token: String,
         videoHash: String,
         videoTitle: String,
         segments: Map<Int, java.io.File>,
         scores: Map<Int, cn.learningpad.oraltrainer.sdk.ImitationAssessmentResult>,
     ): String {
+        require(token.isNotBlank()) { "Login required." }
         val previousPolicy = StrictMode.getThreadPolicy()
         StrictMode.setThreadPolicy(StrictMode.ThreadPolicy.Builder().detectAll().penaltyLog().build())
         val boundary = "oral-trainer-${System.currentTimeMillis()}"
@@ -25,6 +27,7 @@ internal class DubbingShareApi {
             connection.doOutput = true
             connection.connectTimeout = 15_000
             connection.readTimeout = 120_000
+            connection.setRequestProperty("Authorization", "Bearer $token")
             connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=$boundary")
 
             DataOutputStream(connection.outputStream).use { output ->
@@ -83,7 +86,9 @@ internal class DubbingShareApi {
             val code = connection.responseCode
             val body = (if (code in 200..299) connection.inputStream else connection.errorStream)
                 ?.bufferedReader()?.use { it.readText() }.orEmpty()
-            require(code in 200..299) { "HTTP $code: $body" }
+            if (code !in 200..299) {
+                throw IllegalStateException(friendlyShareError(code, body))
+            }
             val response = JSONObject(body).getString("share_id")
             return "$baseUrl/dub-shares/$response"
         } finally {
@@ -91,4 +96,19 @@ internal class DubbingShareApi {
             StrictMode.setThreadPolicy(previousPolicy)
         }
     }
+
+    private fun friendlyShareError(code: Int, body: String): String {
+        val detail = runCatching { JSONObject(body).optString("detail") }.getOrNull()
+            ?.takeIf { it.isNotBlank() }
+            ?: body
+        return when {
+            code == 401 ||
+                detail.contains("Login required", ignoreCase = true) ||
+                detail.contains("sign in", ignoreCase = true) ||
+                detail.contains("Session expired", ignoreCase = true) ->
+                "还未登录或登录已过期，请重新登录后再分享"
+            detail.isNotBlank() -> "HTTP $code: $detail"
+            else -> "HTTP $code"
+        }
+    }
 }
diff --git a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingState.kt b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingState.kt
index e1f7fb8..fab15dd 100644
--- a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingState.kt
+++ b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/DubbingState.kt
@@ -8,12 +8,29 @@ internal class DubbingState {
         private set
 
     fun storeSegment(sentenceIndex: Int, file: File) {
-        segments[sentenceIndex]?.delete()
-        segments[sentenceIndex] = file
+        val previous = segments.put(sentenceIndex, file)
+        if (previous != null && previous.absolutePath != file.absolutePath) {
+            previous.delete()
+        }
         mergedFile = null
     }
 
-    fun setMergedFile(file: File) {
+    fun setMergedFile(file: File?) {
         mergedFile = file
     }
+
+    fun replaceAll(newSegments: Map<Int, File>, merged: File?) {
+        val keep = newSegments.values.map { it.absolutePath }.toHashSet()
+        segments.values
+            .filter { it.absolutePath !in keep }
+            .forEach { /* keep history files on disk; only drop memory refs */ }
+        segments.clear()
+        segments.putAll(newSegments)
+        mergedFile = merged?.takeIf { it.exists() }
+    }
+
+    fun clearMemory() {
+        segments.clear()
+        mergedFile = null
+    }
 }
diff --git a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/MainActivity.kt b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/MainActivity.kt
index fdf0039..6589f2e 100644
--- a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/MainActivity.kt
+++ b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/MainActivity.kt
@@ -32,6 +32,7 @@ class MainActivity : Activity() {
     private val dubbingState = DubbingState()
     private val assessmentState = AssessmentState()
     private val dubbingShareApi = DubbingShareApi()
+    private lateinit var dubbingHistoryStore: DubbingHistoryStore
 
     private lateinit var attemptRecorder: AttemptRecorder
     private lateinit var dubbingMerger: DubbingMerger
@@ -57,6 +58,7 @@ class MainActivity : Activity() {
         attemptRecorder = AttemptRecorder(this)
         dubbingMerger = DubbingMerger(cacheDir)
         dubbingPlaybackController = DubbingPlayback(this)
+        dubbingHistoryStore = DubbingHistoryStore(this)
         configureWindow()
 
         authSessionStore = AuthSessionStore(this)
@@ -89,6 +91,9 @@ class MainActivity : Activity() {
             dubbingShareApi = dubbingShareApi,
             dubbingPlayback = dubbingPlaybackController,
             assessmentState = assessmentState,
+            historyStore = dubbingHistoryStore,
+            userApi = sdk.userApi,
+            tokenProvider = { authSessionStore.session?.token.orEmpty() },
             host = testHost(),
         )
 
@@ -109,6 +114,7 @@ class MainActivity : Activity() {
         screenFactory.renderCatalog()
         refreshCurrentUi()
         if (screenState.activeModule == Module.TEST) {
+            testSession.ensureHistoryForCurrentCourse()
             testSession.refreshTestUi()
         }
     }
@@ -268,6 +274,9 @@ class MainActivity : Activity() {
     }
 
     private fun switchModule(module: Module) {
+        if (module != Module.TEST) {
+            testSession.stopDubbingIfNeeded()
+        }
         screenState.activeModule = module
         if (module == Module.COURSE || module == Module.MINE) {
             catalogController.loadUserData(module) {
@@ -310,9 +319,14 @@ class MainActivity : Activity() {
         }
 
         override fun onMediaChanged(item: TrainingMediaItem?) {
-            if (!bindings.hasPlayerChrome) return
-            bindings.lessonTitleText.text = item?.title ?: "未选择课程"
-            screenState.currentSentenceCount = item?.sentences?.size ?: 0
+            if (bindings.hasPlayerChrome) {
+                bindings.lessonTitleText.text = item?.title ?: "未选择课程"
+                screenState.currentSentenceCount = item?.sentences?.size ?: 0
+            }
+            testSession.ensureHistoryForCurrentCourse()
+            if (screenState.activeModule == Module.TEST) {
+                testSession.refreshTestUi()
+            }
         }
 
         override fun onSentenceChanged(sentence: SentenceBoundary?) {
@@ -408,15 +422,21 @@ class MainActivity : Activity() {
         }
 
         override fun onPrevSentence() {
+            testSession.stopDubbingIfNeeded()
             controller.seekToPreviousSentence()
+            testSession.refreshTestUi()
         }
 
         override fun onReplaySentence() {
+            testSession.stopDubbingIfNeeded()
+            testSession.refreshTestUi()
             controller.playCurrentSentenceAndStop()
         }
 
         override fun onNextSentence() {
+            testSession.stopDubbingIfNeeded()
             controller.seekToNextSentence()
+            testSession.refreshTestUi()
         }
 
         override fun onToggleRecording() = testSession.toggleRecording()
diff --git a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/SampleTheme.kt b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/SampleTheme.kt
index 935cdf2..a78d97f 100644
--- a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/SampleTheme.kt
+++ b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/SampleTheme.kt
@@ -19,5 +19,6 @@ internal object SampleTheme {
     val textDark = Color.rgb(18, 24, 31)
     val textMuted = Color.rgb(151, 162, 174)
     val textSubtle = Color.rgb(88, 98, 108)
+    val danger = Color.rgb(220, 38, 38)
     val textOverlay = Color.rgb(163, 172, 182)
 }
diff --git a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/TestSessionController.kt b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/TestSessionController.kt
index e5ebce9..f5b5e11 100644
--- a/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/TestSessionController.kt
+++ b/android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/TestSessionController.kt
@@ -5,13 +5,18 @@ import android.app.Activity
 import android.content.Intent
 import android.content.pm.PackageManager
 import android.net.Uri
+import android.os.Handler
+import android.os.Looper
 import android.util.Log
 import android.view.View
 import cn.learningpad.oraltrainer.sdk.ImitationAssessmentCallback
 import cn.learningpad.oraltrainer.sdk.ImitationAssessmentResult
 import cn.learningpad.oraltrainer.sdk.OralTrainerController
+import cn.learningpad.oraltrainer.sdk.UserApi
 import java.io.File
 import java.util.Locale
+import java.util.concurrent.Executors
+import java.util.concurrent.atomic.AtomicInteger
 
 /** Recording, assessment, and dubbing flow for the TEST module. */
 internal class TestSessionController(
@@ -24,6 +29,9 @@ internal class TestSessionController(
     private val dubbingShareApi: DubbingShareApi,
     private val dubbingPlayback: DubbingPlayback,
     private val assessmentState: AssessmentState,
+    private val historyStore: DubbingHistoryStore,
+    private val userApi: UserApi,
+    private val tokenProvider: () -> String,
     private val host: Host,
 ) {
     interface Host {
@@ -33,6 +41,15 @@ internal class TestSessionController(
         fun refreshPlayerUi()
     }
 
+    private val mainHandler = Handler(Looper.getMainLooper())
+    private val background = Executors.newSingleThreadExecutor()
+    private val remoteLoadGeneration = AtomicInteger(0)
+
+    private var loadedVideoHash: String? = null
+    private var assessing = false
+    private var sharing = false
+    private var historyStatusMessage: String? = null
+
     val isDubbingActive: Boolean
         get() = dubbingPlayback.isActive
 
@@ -47,8 +64,10 @@ internal class TestSessionController(
     }
 
     fun release() {
+        remoteLoadGeneration.incrementAndGet()
         attemptRecorder.discard()
         dubbingPlayback.release()
+        background.shutdownNow()
     }
 
     fun stopDubbingIfNeeded() {
@@ -57,7 +76,29 @@ internal class TestSessionController(
         }
     }
 
+    /** Loads local (and if needed remote) history for the active cloud course. */
+    fun ensureHistoryForCurrentCourse(forceRemote: Boolean = false) {
+        val videoHash = currentVideoHash()
+        if (videoHash == null) {
+            if (loadedVideoHash != null) {
+                loadedVideoHash = null
+                dubbingState.clearMemory()
+                assessmentState.clear()
+                historyStatusMessage = null
+            }
+            return
+        }
+        if (loadedVideoHash == videoHash && !forceRemote) {
+            return
+        }
+        loadLocalHistory(videoHash)
+        if (forceRemote || dubbingState.segments.isEmpty()) {
+            restoreRemoteHistory(videoHash)
+        }
+    }
+
     fun refreshTestUi() {
+        ensureHistoryForCurrentCourse()
         val ui = host.bindings
         if (!ui.hasTestChrome) {
             return
@@ -68,22 +109,40 @@ internal class TestSessionController(
         val sentence = controller.currentSentence()
         val currentRecording = sentence?.let { dubbingState.segments[it.index] }
         val segmentLabel = when {
-            currentRecording != null -> " · 本句已录音，重录将覆盖"
-            else -> ""
+            currentRecording != null -> "本句已有配音，重录将覆盖"
+            else -> null
         }
-        ui.testStatusText.text = if (item == null || sentence == null) {
-            "请先在训练模块选择课程$segmentLabel"
-        } else {
-            "评测对象：第 ${sentence.index + 1} 句（共 ${item.sentences.size} 句）$segmentLabel"
-        }
-        refreshDubButtons()
-        if (dubbingState.mergedFile == null) {
-            ui.dubbingStatusText?.text = when (dubbingState.segments.size) {
-                0 -> "配音：请先录音"
-                1 -> "配音：已保存 1 句，可生成配音"
-                else -> "配音：已保存 ${dubbingState.segments.size} 句，可生成配音"
+
+        if (!assessing && !attemptRecorder.isRecording) {
+            val score = sentence?.let { assessmentState.get(it.index) }
+            if (score != null) {
+                applyAssessmentResult(score, segmentLabel)
+            } else {
+                ui.testStatusText.text = when {
+                    item == null || sentence == null -> "请先在训练模块选择课程"
+                    segmentLabel != null -> "评测对象：第 ${sentence.index + 1} 句（共 ${item.sentences.size} 句） · $segmentLabel"
+                    else -> "评测对象：第 ${sentence.index + 1} 句（共 ${item.sentences.size} 句）"
+                }
+                ui.scoreSummaryText.text = "尚未评测"
+                ui.scoreDetailText.text = ""
             }
         }
+
+        refreshDubButtons()
+        if (!sharing) {
+            val historyNote = historyStatusMessage
+            if (dubbingState.mergedFile?.exists() == true) {
+                ui.dubbingStatusText?.text = historyNote
+                    ?: "已合成 ${dubbingState.segments.size} 句配音，可点击“分享配音”"
+            } else {
+                ui.dubbingStatusText?.text = historyNote ?: when (dubbingState.segments.size) {
+                    0 -> "配音：请先录音（进入本页会自动加载历史配音）"
+                    1 -> "配音：已保存 1 句，可生成配音"
+                    else -> "配音：已保存 ${dubbingState.segments.size} 句，可生成配音"
+                }
+            }
+            ui.dubbingStatusText?.setTextColor(SampleTheme.accentDeep)
+        }
     }
 
     fun toggleRecording() {
@@ -95,6 +154,7 @@ internal class TestSessionController(
     }
 
     fun startRecording() {
+        stopDubbingIfNeeded()
         controller.pause()
         val ui = host.bindings
         if (!ui.hasTestChrome) {
@@ -136,18 +196,41 @@ internal class TestSessionController(
             host.setMainStatus("已停止配音播放")
             return
         }
-        val audio = dubbingState.mergedFile ?: activeAudioForPlayback() ?: return
-        startDubPlayback(audio)
+        val sentence = controller.currentSentence()
+        if (sentence == null) {
+            host.setMainStatus("请先选择要播放的句子")
+            return
+        }
+        val audio = dubbingState.segments[sentence.index]
+        if (audio == null || !audio.exists()) {
+            host.setMainStatus("当前句还没有录音，请先录音后再播放")
+            refreshTestUi()
+            return
+        }
+        startDubPlayback(audio, sentence.startMs, sentence.index)
     }
 
     fun mergeDubSegments() {
+        stopDubbingIfNeeded()
+        val videoHash = currentVideoHash()
         val segments = dubbingState.segments.toSortedMap().map { (index, file) -> index to file }
         if (segments.isEmpty()) {
+            setDubbingStatus("没有可合成的配音")
             return
         }
         try {
             val output = dubbingMerger.merge(segments)
-            dubbingState.setMergedFile(output)
+            val persisted = if (videoHash != null) {
+                historyStore.saveMerged(videoHash, output).also {
+                    if (it.absolutePath != output.absolutePath) {
+                        output.delete()
+                    }
+                }
+            } else {
+                output
+            }
+            dubbingState.setMergedFile(persisted)
+            historyStatusMessage = null
             refreshTestUi()
             setDubbingStatus("已合成 ${segments.size} 句配音，可点击“分享配音”")
         } catch (error: Throwable) {
@@ -160,30 +243,62 @@ internal class TestSessionController(
     }
 
     fun shareMergedDubbing() {
+        stopDubbingIfNeeded()
+        if (sharing) {
+            return
+        }
         val item = controller.currentTrainingItem()
         if (item == null || !PlaybackFormat.isVideoHash(item.id)) {
             setDubbingStatus("分享失败：网页分享仅支持云端课程视频")
             return
         }
-        try {
-            val shareUrl = dubbingShareApi.upload(
-                baseUrl = SERVER_BASE_URL,
-                videoHash = item.id,
-                videoTitle = item.title,
-                segments = dubbingState.segments,
-                scores = assessmentState.toMap(),
-            )
-            val intent = Intent(Intent.ACTION_SEND).apply {
-                type = "text/plain"
-                putExtra(Intent.EXTRA_TEXT, "我的口语配音：$shareUrl")
-                putExtra(Intent.EXTRA_TITLE, "我的口语配音")
-                addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+        val token = tokenProvider().trim()
+        if (token.isEmpty()) {
+            setDubbingStatus("分享失败：请先登录后再分享配音")
+            return
+        }
+        val segmentsSnapshot = dubbingState.segments.toMap()
+        val scoresSnapshot = assessmentState.toMap()
+        val videoHash = item.id
+        val videoTitle = item.title
+        sharing = true
+        setDubbingStatus("正在生成分享链接，请稍候...", alert = true)
+        refreshDubButtons()
+        background.execute {
+            try {
+                val shareUrl = dubbingShareApi.upload(
+                    baseUrl = SERVER_BASE_URL,
+                    token = token,
+                    videoHash = videoHash,
+                    videoTitle = videoTitle,
+                    segments = segmentsSnapshot,
+                    scores = scoresSnapshot,
+                )
+                mainHandler.post {
+                    sharing = false
+                    if (!host.bindings.hasTestChrome) {
+                        return@post
+                    }
+                    val intent = Intent(Intent.ACTION_SEND).apply {
+                        type = "text/plain"
+                        putExtra(Intent.EXTRA_TEXT, "我的口语配音：$shareUrl")
+                        putExtra(Intent.EXTRA_TITLE, "我的口语配音")
+                        addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+                    }
+                    activity.startActivity(Intent.createChooser(intent, "分享配音"))
+                    setDubbingStatus("已生成分享链接：$shareUrl")
+                    refreshDubButtons()
+                }
+            } catch (error: Throwable) {
+                Log.e(TAG, "share failed", error)
+                val detail = error.message?.takeIf { it.isNotBlank() }
+                    ?: error.javaClass.simpleName
+                mainHandler.post {
+                    sharing = false
+                    setDubbingStatus("分享失败：$detail", alert = true)
+                    refreshDubButtons()
+                }
             }
-            activity.startActivity(Intent.createChooser(intent, "分享配音"))
-            setDubbingStatus("已生成分享链接：$shareUrl")
-        } catch (error: Throwable) {
-            Log.e(TAG, "share failed", error)
-            setDubbingStatus("分享失败：${error.javaClass.simpleName}: ${error.message.orEmpty()}")
         }
     }
 
@@ -195,6 +310,160 @@ internal class TestSessionController(
         refreshTestUi()
     }
 
+    private fun loadLocalHistory(videoHash: String) {
+        val snapshot = historyStore.loadSnapshot(videoHash)
+        dubbingState.replaceAll(snapshot.segments, snapshot.mergedFile)
+        assessmentState.replaceAll(snapshot.scores)
+        loadedVideoHash = videoHash
+        historyStatusMessage = when {
+            snapshot.segments.isNotEmpty() && snapshot.scores.isNotEmpty() ->
+                "已加载历史配音 ${snapshot.segments.size} 句、评分 ${snapshot.scores.size} 句"
+            snapshot.segments.isNotEmpty() ->
+                "已加载历史配音 ${snapshot.segments.size} 句"
+            snapshot.scores.isNotEmpty() ->
+                "已加载历史评分 ${snapshot.scores.size} 句（暂无本地录音）"
+            else -> null
+        }
+        Log.i(
+            TAG,
+            "loaded local history video=$videoHash segments=${snapshot.segments.size} scores=${snapshot.scores.size}",
+        )
+    }
+
+    private fun restoreRemoteHistory(videoHash: String) {
+        val token = tokenProvider().trim()
+        if (token.isEmpty()) {
+            return
+        }
+        val generation = remoteLoadGeneration.incrementAndGet()
+        historyStatusMessage = when {
+            dubbingState.segments.isEmpty() && assessmentState.size == 0 -> "正在同步历史配音…"
+            else -> historyStatusMessage
+        }
+        if (host.bindings.hasTestChrome) {
+            host.bindings.dubbingStatusText?.text = historyStatusMessage
+        }
+
+        // Latest score summary per sentence.
+        userApi.results(token) { result ->
+            if (generation != remoteLoadGeneration.get() || loadedVideoHash != videoHash) {
+                return@results
+            }
+            result.onSuccess { rows ->
+                val latestBySentence = linkedMapOf<Int, cn.learningpad.oraltrainer.sdk.UserResult>()
+                rows.filter { it.videoHash.equals(videoHash, ignoreCase = true) }
+                    .sortedBy { it.createdAt }
+                    .forEach { latestBySentence[it.sentenceIndex] = it }
+                var added = 0
+                latestBySentence.forEach { (index, row) ->
+                    if (assessmentState.get(index) == null) {
+                        assessmentState.store(
+                            index,
+                            ImitationAssessmentResult(
+                                overallScore = row.overallScore,
+                                passed = row.passed,
+                                referenceText = row.sentenceText.takeIf { it.isNotBlank() },
+                                feedback = "来自历史测试记录",
+                            ),
+                        )
+                        added += 1
+                    }
+                }
+                if (added > 0) {
+                    historyStore.saveScores(videoHash, assessmentState.toMap())
+                    historyStatusMessage = "已同步历史评分 ${assessmentState.size} 句"
+                    refreshTestUi()
+                }
+            }
+        }
+
+        // Latest shared dubbing audio for this course.
+        userApi.dubShares(token) { shareResult ->
+            if (generation != remoteLoadGeneration.get() || loadedVideoHash != videoHash) {
+                return@dubShares
+            }
+            val latestShare = shareResult.getOrNull()
+                ?.filter { it.videoHash.equals(videoHash, ignoreCase = true) }
+                ?.maxByOrNull { it.createdAt }
+            if (latestShare == null) {
+                if (dubbingState.segments.isEmpty() && assessmentState.size == 0) {
+                    historyStatusMessage = "暂无历史配音，请开始录音"
+                    if (host.bindings.hasTestChrome) {
+                        host.bindings.dubbingStatusText?.text = historyStatusMessage
+                    }
+                }
+                return@dubShares
+            }
+            if (dubbingState.segments.isNotEmpty()) {
+                return@dubShares
+            }
+            userApi.dubShareDetail(latestShare.shareId) { detailResult ->
+                if (generation != remoteLoadGeneration.get() || loadedVideoHash != videoHash) {
+                    return@dubShareDetail
+                }
+                val detail = detailResult.getOrNull() ?: run {
+                    Log.w(TAG, "dub share detail failed: ${detailResult.exceptionOrNull()?.message}")
+                    return@dubShareDetail
+                }
+                background.execute {
+                    val downloaded = linkedMapOf<Int, File>()
+                    val remoteScores = linkedMapOf<Int, ImitationAssessmentResult>()
+                    detail.segments.forEach { segment ->
+                        val file = historyStore.downloadSegmentAudio(
+                            baseUrl = SERVER_BASE_URL,
+                            videoHash = videoHash,
+                            sentenceIndex = segment.index,
+                            audioUrl = segment.audioUrl,
+                        )
+                        if (file != null) {
+                            downloaded[segment.index] = file
+                        }
+                        if (assessmentState.get(segment.index) == null) {
+                            remoteScores[segment.index] = ImitationAssessmentResult(
+                                overallScore = segment.overallScore,
+                                contentScore = segment.scoreDetails["content_score"],
+                                fluencyScore = segment.scoreDetails["fluency_score"],
+                                durationScore = segment.scoreDetails["duration_score"],
+                                pauseScore = segment.scoreDetails["pause_score"],
+                                speechRateScore = segment.scoreDetails["speech_rate_score"],
+                                recognizedText = segment.recognizedText.takeIf { it.isNotBlank() },
+                                feedback = "来自历史配音分享",
+                            )
+                        }
+                    }
+                    mainHandler.post {
+                        if (generation != remoteLoadGeneration.get() || loadedVideoHash != videoHash) {
+                            return@post
+                        }
+                        if (downloaded.isNotEmpty()) {
+                            val mergedSegments = dubbingState.segments.toMutableMap()
+                            mergedSegments.putAll(downloaded)
+                            dubbingState.replaceAll(mergedSegments, dubbingState.mergedFile)
+                        }
+                        if (remoteScores.isNotEmpty()) {
+                            val mergedScores = assessmentState.toMap().toMutableMap()
+                            remoteScores.forEach { (index, score) ->
+                                if (mergedScores[index] == null) {
+                                    mergedScores[index] = score
+                                }
+                            }
+                            assessmentState.replaceAll(mergedScores)
+                            historyStore.saveScores(videoHash, assessmentState.toMap())
+                        }
+                        historyStatusMessage = when {
+                            downloaded.isNotEmpty() ->
+                                "已从云端恢复配音 ${downloaded.size} 句"
+                            assessmentState.size > 0 ->
+                                "已同步历史评分 ${assessmentState.size} 句"
+                            else -> "暂无可用的历史配音音频"
+                        }
+                        refreshTestUi()
+                    }
+                }
+            }
+        }
+    }
+
     private fun stopRecordingAndAssess() {
         if (!attemptRecorder.isRecording) return
         val ui = host.bindings
@@ -215,12 +484,28 @@ internal class TestSessionController(
             refreshTestUi()
             return
         }
-        dubbingState.storeSegment(sentenceIndex, file)
-        submitAssessment(Uri.fromFile(file))
+        val videoHash = currentVideoHash()
+        val persisted = if (videoHash != null) {
+            try {
+                historyStore.saveSegment(videoHash, sentenceIndex, file).also {
+                    if (it.absolutePath != file.absolutePath) {
+                        file.delete()
+                    }
+                }
+            } catch (error: Throwable) {
+                Log.e(TAG, "persist segment failed", error)
+                file
+            }
+        } else {
+            file
+        }
+        dubbingState.storeSegment(sentenceIndex, persisted)
+        historyStatusMessage = null
+        submitAssessment(Uri.fromFile(persisted), sentenceIndex)
         refreshTestUi()
     }
 
-    private fun submitAssessment(recordingUri: Uri) {
+    private fun submitAssessment(recordingUri: Uri, sentenceIndex: Int) {
         val ui = host.bindings
         val item = controller.currentTrainingItem()
         val sentence = controller.currentSentence()
@@ -236,6 +521,7 @@ internal class TestSessionController(
             ui.testStatusText.text = "未配置评分密钥：请在 AppConfig 填入服务器 .env 的 CLIENT_API_KEY"
             return
         }
+        assessing = true
         ui.testStatusText.text = "正在评测第 ${sentence.index + 1} 句，请稍候…"
         ui.scoreSummaryText.text = "评测中…"
         ui.scoreDetailText.text = ""
@@ -247,13 +533,24 @@ internal class TestSessionController(
             metadata = mapOf("video_hash" to item.id),
             callback = object : ImitationAssessmentCallback {
                 override fun onResult(result: ImitationAssessmentResult) {
+                    assessing = false
+                    assessmentState.store(sentenceIndex, result)
+                    currentVideoHash()?.let { hash ->
+                        historyStore.saveScores(hash, assessmentState.toMap())
+                    }
                     if (host.bindings.hasTestChrome) {
                         applyAssessmentResult(result)
+                        refreshDubButtons()
+                        host.bindings.dubbingStatusText?.text = when (dubbingState.segments.size) {
+                            0 -> "配音：请先录音"
+                            1 -> "配音：已保存 1 句，可生成配音"
+                            else -> "配音：已保存 ${dubbingState.segments.size} 句，可生成配音"
+                        }
                     }
-                    assessmentState.store(sentence.index, result)
                 }
 
                 override fun onError(error: Throwable) {
+                    assessing = false
                     if (host.bindings.hasTestChrome) {
                         host.bindings.testStatusText.text = "评测失败：${error.message.orEmpty()}"
                         host.bindings.scoreSummaryText.text = "评测失败"
@@ -263,9 +560,17 @@ internal class TestSessionController(
         )
     }
 
-    private fun applyAssessmentResult(result: ImitationAssessmentResult) {
+    private fun applyAssessmentResult(
+        result: ImitationAssessmentResult,
+        segmentLabel: String? = null,
+    ) {
         val ui = host.bindings
-        ui.testStatusText.text = if (result.passed == true) "已通过" else "未通过"
+        val passLabel = when (result.passed) {
+            true -> "已通过"
+            false -> "未通过"
+            null -> "已评测"
+        }
+        ui.testStatusText.text = listOfNotNull(passLabel, segmentLabel).joinToString(" · ")
         ui.scoreSummaryText.text = String.format(Locale.US, "总分 %.1f", result.overallScore)
         ui.scoreDetailText.text = buildString {
             result.contentScore?.let { appendLine(String.format(Locale.US, "内容分 %.1f", it)) }
@@ -302,49 +607,51 @@ internal class TestSessionController(
 
     private fun refreshDubButtons() {
         val ui = host.bindings
+        if (!ui.hasTestChrome) {
+            return
+        }
         val dubbingActive = dubbingPlayback.isActive
-        ui.playDubButton.isEnabled = dubbingState.segments.isNotEmpty() && !dubbingActive
+        val currentSentenceAudio = controller.currentSentence()?.let { dubbingState.segments[it.index] }
+        // Keep the play button tappable while active so the user can stop playback.
+        ui.playDubButton.isEnabled = dubbingActive || currentSentenceAudio != null
         ui.mergeDubButton.isEnabled = dubbingState.segments.isNotEmpty() && !dubbingActive
-        ui.shareDubButton.isEnabled = dubbingState.mergedFile?.exists() == true && !dubbingActive
-        val activeAudio = controller.currentSentence()?.let { dubbingState.segments[it.index] }
+        ui.shareDubButton.isEnabled =
+            dubbingState.mergedFile?.exists() == true && !dubbingActive && !sharing
         ui.playDubButton.text = when {
-            dubbingActive -> "停止配音"
-            dubbingState.mergedFile?.exists() == true -> "播放配音"
-            activeAudio != null -> "播放本句配音"
-            else -> "播放录音（${dubbingState.segments.size}）"
+            dubbingActive -> "停止播放"
+            currentSentenceAudio != null -> "播放本句录音"
+            dubbingState.segments.isNotEmpty() -> "播放本句录音"
+            else -> "播放录音"
         }
     }
 
-    private fun activeAudioForPlayback(): File? {
-        if (dubbingState.mergedFile != null) {
-            return dubbingState.mergedFile
-        }
-        return controller.currentSentence()?.let { sentence -> dubbingState.segments[sentence.index] }
-    }
-
-    private fun startDubPlayback(audioFile: File) {
-        val sentence = controller.currentSentence()
+    private fun startDubPlayback(audioFile: File, sentenceStartMs: Long, sentenceIndex: Int) {
         dubbingPlayback.start(
             audioFile = audioFile,
             controller = controller,
-            syncToSentence = dubbingState.mergedFile == null,
-            sentenceStartMs = sentence?.startMs,
+            sentenceStartMs = sentenceStartMs,
+            sentenceIndex = sentenceIndex,
         ) {
             refreshTestUi()
-            host.setMainStatus("配音播放完成")
+            host.setMainStatus("本句录音播放完成")
         }
         refreshTestUi()
-        host.setMainStatus(
-            if (dubbingState.mergedFile == null) {
-                "正在播放当前句配音，原视频画面同步但原声静音"
-            } else {
-                "正在播放整段配音，原视频画面同步但原声静音"
-            },
-        )
+        host.setMainStatus("正在播放当前句录音，原视频画面同步但原声静音")
     }
 
-    private fun setDubbingStatus(message: String) {
-        host.bindings.dubbingStatusText?.text = message
+    private fun setDubbingStatus(message: String, alert: Boolean = false) {
+        historyStatusMessage = null
+        host.bindings.dubbingStatusText?.apply {
+            text = message
+            setTextColor(if (alert) SampleTheme.danger else SampleTheme.accentDeep)
+        }
+    }
+
+    private fun currentVideoHash(): String? {
+        val id = controller.currentTrainingItem()?.id
+            ?: screenState.currentCourse?.videoHash
+            ?: screenState.activeItemId
+        return DubbingHistoryStore.normalize(id.orEmpty())
     }
 
     private companion object {
diff --git a/ios/OralTrainer/Services/ImitationAssessor.swift b/ios/OralTrainer/Services/ImitationAssessor.swift
index ff34376..464e2d8 100644
--- a/ios/OralTrainer/Services/ImitationAssessor.swift
+++ b/ios/OralTrainer/Services/ImitationAssessor.swift
@@ -171,15 +171,19 @@ enum ImitationAssessor {
         }
         body.append(Data("--\(boundary)--\r\n".utf8))
 
+        var headers = [
+            "Accept": "application/json",
+            "Content-Type": "multipart/form-data; boundary=\(boundary)",
+        ]
+        if !AppConfig.authToken.isEmpty {
+            headers["Authorization"] = "Bearer \(AppConfig.authToken)"
+        }
         let result = try await HTTPClient.execute(
             baseURL: AppConfig.serverBaseURL,
             path: "api/v1/dub-shares",
             method: "POST",
             timeout: 120,
-            headers: [
-                "Accept": "application/json",
-                "Content-Type": "multipart/form-data; boundary=\(boundary)",
-            ],
+            headers: headers,
             body: body
         )
         guard (200...299).contains(result.statusCode) else {
diff --git a/ios/OralTrainer/Views/TestView.swift b/ios/OralTrainer/Views/TestView.swift
index b12d4b5..cdba569 100644
--- a/ios/OralTrainer/Views/TestView.swift
+++ b/ios/OralTrainer/Views/TestView.swift
@@ -58,13 +58,16 @@ struct TestView: View {
                 }
                 HStack(spacing: 8) {
                     sentenceButton("上一句") {
+                        stopDubPlayback(message: nil)
                         controller.seekToPreviousSentence()
                     }
                     sentenceButton("播放原句") {
+                        stopDubPlayback(message: nil)
                         controller.playCurrentSentenceAndStop()
                         controller.showTransientMessage("正在播放当前句子，播放完自动停止")
                     }
                     sentenceButton("下一句") {
+                        stopDubPlayback(message: nil)
                         controller.seekToNextSentence()
                     }
                 }
@@ -80,19 +83,24 @@ struct TestView: View {
                 .buttonStyle(.plain)
                 .disabled(isAssessing)
                 HStack(spacing: 8) {
-                    dubButton("播放配音", enabled: !dubSegments.isEmpty && !dubbingPlayback && !isGeneratingDub) {
+                    dubButton(
+                        dubbingPlayback ? "停止播放" : "播放本句录音",
+                        enabled: dubbingPlayback || (controller.currentSentence.flatMap { dubSegments[$0.index] } != nil)
+                    ) {
                         toggleDubPlayback()
                     }
                     dubButton("生成配音", enabled: !dubRawSegments.isEmpty && !dubbingPlayback && !isGeneratingDub) {
+                        stopDubPlayback(message: nil)
                         generateDubShareAudio()
                     }
                     dubButton("分享配音", enabled: mergedDubURL != nil && !dubbingPlayback && !isSharingDub) {
+                        stopDubPlayback(message: nil)
                         shareMergedDub()
                     }
                 }
                 Text(dubbingStatus)
                     .font(.system(size: 13))
-                    .foregroundColor(Theme.accentDeep)
+                    .foregroundColor(isSharingDub ? Theme.danger : Theme.accentDeep)
                     .frame(maxWidth: .infinity, alignment: .leading)
                 Text(scoreSummary)
                     .font(.system(size: 22, weight: .bold))
@@ -159,6 +167,7 @@ struct TestView: View {
     // MARK: - 录音
 
     private func toggleRecording() {
+        stopDubPlayback(message: nil)
         if isRecording {
             stopRecordingAndAssess()
         } else {
@@ -394,32 +403,40 @@ struct TestView: View {
 
     private func toggleDubPlayback() {
         if dubbingPlayback {
-            stopDubPlayback(message: "已停止配音播放")
+            stopDubPlayback(message: "已停止录音播放")
             return
         }
-        let sentence = controller.currentSentence
-        let audioURL = mergedDubURL ?? sentence.flatMap { dubSegments[$0.index] }
-        guard let audioURL else { return }
-        if mergedDubURL == nil, let sentence = sentence {
-            controller.seek(to: sentence.startMs)
+        guard let sentence = controller.currentSentence else {
+            dubbingStatus = "请先选择要播放的句子"
+            return
         }
+        guard let audioURL = dubSegments[sentence.index] else {
+            dubbingStatus = "当前句还没有录音，请先录音后再播放"
+            return
+        }
+        // Always play the current sentence recording only (never the merged full track).
+        stopDubPlayback(message: nil)
+        controller.seek(to: sentence.startMs)
         controller.pause()
         controller.setVolume(0)
         let player = dubPlayer ?? AVPlayer()
         dubPlayer = player
-        player.replaceCurrentItem(with: AVPlayerItem(url: audioURL))
+        let item = AVPlayerItem(url: audioURL)
+        player.replaceCurrentItem(with: item)
         dubbingPlayback = true
-        dubbingStatus = mergedDubURL == nil ? "正在播放当前句配音，视频原声静音" : "正在播放整段配音，视频原声静音"
+        dubbingStatus = "正在播放当前句录音"
         player.play()
-        if dubPlaybackObserver == nil {
-            dubPlaybackObserver = NotificationCenter.default.addObserver(
-                forName: AVPlayerItem.didPlayToEndTimeNotification,
-                object: player.currentItem,
-                queue: .main
-            ) { _ in
-                DispatchQueue.main.asyncAfter(deadline: .now() + 0.25) {
-                    stopDubPlayback(message: "配音播放完成")
-                }
+        if let dubPlaybackObserver {
+            NotificationCenter.default.removeObserver(dubPlaybackObserver)
+            self.dubPlaybackObserver = nil
+        }
+        dubPlaybackObserver = NotificationCenter.default.addObserver(
+            forName: AVPlayerItem.didPlayToEndTimeNotification,
+            object: item,
+            queue: .main
+        ) { _ in
+            DispatchQueue.main.asyncAfter(deadline: .now() + 0.25) {
+                stopDubPlayback(message: "本句录音播放完成")
             }
         }
     }
@@ -468,7 +485,7 @@ struct TestView: View {
             return
         }
         isSharingDub = true
-        dubbingStatus = "正在生成分享链接…"
+        dubbingStatus = "正在生成分享链接，请稍候..."
         let request = DubShareUploadRequest(
             videoHash: item.id,
             title: item.title,
diff --git a/ios/OralTrainer/Views/Theme.swift b/ios/OralTrainer/Views/Theme.swift
index fd53041..799cc49 100644
--- a/ios/OralTrainer/Views/Theme.swift
+++ b/ios/OralTrainer/Views/Theme.swift
@@ -17,6 +17,7 @@ enum Theme {
     static let textDark = Color(hex: 0x12181F)
     static let textMuted = Color(hex: 0x97A2AE)
     static let textSubtle = Color(hex: 0x58626C)
+    static let danger = Color(hex: 0xDC2626)
     static let textOverlay = Color(hex: 0xA3ACB6)
 
     static func formatTime(_ ms: Int64) -> String {