diff --git a/app-expo/src/app/(main)/conversation/[id].tsx b/app-expo/src/app/(main)/conversation/[id].tsx
index e66984f..d1417e3 100644
--- a/app-expo/src/app/(main)/conversation/[id].tsx
+++ b/app-expo/src/app/(main)/conversation/[id].tsx
@@ -62,6 +62,7 @@ import { useSession } from '@/features/auth/hooks';
 import { useProfile } from '@/features/profile/hooks';
 import {
   assistantSegmentMessageId,
+  playbackListKeyMatchesBubble,
   splitMessageParts,
   splitStreamingSegments,
 } from '@/features/conversation/message-split';
@@ -171,16 +172,6 @@ function segmentTtsUrlAt(
 /** 流式助手区与自动 TTS 的 `PlaybackItem.messageRef.listKey` 对齐，用于点区域停止朗读 */
 const TTS_STREAMING_LIST_KEY = '__tts_streaming__';
 
-/** PlaybackItem.messageRef.listKey 可与 `item.id` 或 `${id}_seg_/part_` 后缀对齐 */
-function playbackMessageRefMatchesMessage(
-  playbackListKey: string | undefined,
-  messageItemId: string,
-): boolean {
-  if (!playbackListKey?.length) return false;
-  if (playbackListKey === messageItemId) return true;
-  return playbackListKey.startsWith(`${messageItemId}_`);
-}
-
 /** 展平消息列表：assistant 消息按 [SPLIT] 边界拆成多条，每条一个 listKey */
 function flattenMessagesForList(
   messages: MessageItem[],
@@ -230,7 +221,9 @@ function MessageBubble({
   onPauseAssistantTts,
   onResumeAssistantTts,
   onInterruptAssistantTts,
+  onPreemptAssistantPlayback,
   onReplayAssistantTts,
+  assistantPlaybackEngaged,
   bubbleTextStyle,
   voiceDurationTextStyle,
   readAloudIconSize,
@@ -254,7 +247,11 @@ function MessageBubble({
   onPauseAssistantTts: () => void;
   onResumeAssistantTts: () => void;
   onInterruptAssistantTts: () => void;
+  /** 切换到另一条助手分段朗读前，仅停止本地播放（不发 tts_cancel） */
+  onPreemptAssistantPlayback: () => void;
   onReplayAssistantTts: (messageId: string, urls: string[]) => void;
+  /** 当前有助手 TTS 在播或已暂停（不含用户语音气泡） */
+  assistantPlaybackEngaged: boolean;
   bubbleTextStyle?: TextStyle;
   voiceDurationTextStyle?: TextStyle;
   readAloudIconSize: number;
@@ -284,8 +281,7 @@ function MessageBubble({
     !isUser &&
     !isVoice &&
     playbackKind !== 'voice' &&
-    (playbackRefListKey === listKey ||
-      playbackMessageRefMatchesMessage(playbackRefListKey, item.id));
+    playbackListKeyMatchesBubble(playbackRefListKey, listKey, item.id);
 
   const playbackEngaged = playbackIsPlaying || playbackIsPaused;
   const isThisBubbleActiveTts = matchesThisMessageForTts && playbackEngaged;
@@ -335,19 +331,26 @@ function MessageBubble({
                 onPauseAssistantTts();
               } else if (isThisBubbleTtsPaused) {
                 onResumeAssistantTts();
-              } else if (ttsUrlThisPart) {
-                onReplayAssistantTts(listKey, [ttsUrlThisPart]);
-              } else if (durableAssistantId) {
-                const ok = requestAssistantSegmentTts({
-                  assistantMessageId: durableAssistantId,
-                  segmentIndex: assistantSegmentIndex,
-                  segmentText: item.content,
-                });
-                if (!ok) {
-                  Alert.alert('', t('readAloudRequestFailed'));
-                }
               } else {
-                Alert.alert('', t('readAloudNoMessageId'));
+                const switchingSegment =
+                  assistantPlaybackEngaged && !isThisBubbleActiveTts;
+                if (switchingSegment) {
+                  onPreemptAssistantPlayback();
+                }
+                if (ttsUrlThisPart) {
+                  onReplayAssistantTts(listKey, [ttsUrlThisPart]);
+                } else if (durableAssistantId) {
+                  const ok = requestAssistantSegmentTts({
+                    assistantMessageId: durableAssistantId,
+                    segmentIndex: assistantSegmentIndex,
+                    segmentText: item.content,
+                  });
+                  if (!ok) {
+                    Alert.alert('', t('readAloudRequestFailed'));
+                  }
+                } else {
+                  Alert.alert('', t('readAloudNoMessageId'));
+                }
               }
             }}
             style={({ pressed }) => [
@@ -432,7 +435,7 @@ function MessageBubble({
         ) : (
           <View style={styles.assistantBubbleWrap}>
             {assistantTextBubbleBody}
-            {isThisBubbleActiveTts ? (
+            {isThisBubbleTtsPlaying ? (
               <Pressable
                 onPress={onInterruptAssistantTts}
                 style={({ pressed }) => [
@@ -1470,6 +1473,14 @@ export default function ConversationScreen() {
     pausePlayback();
   }, [pausePlayback]);
 
+  const handlePreemptAssistantPlayback = useCallback(() => {
+    void stop();
+  }, [stop]);
+
+  const assistantPlaybackEngaged =
+    (playerStatus === 'playing' || playerStatus === 'paused') &&
+    currentPlaybackItem?.kind !== 'voice';
+
   const handleResumeAssistantPlayback = useCallback(() => {
     void resumePlayback();
   }, [resumePlayback]);
@@ -1918,7 +1929,9 @@ export default function ConversationScreen() {
             onResumeAssistantTts={handleResumeAssistantPlayback}
             onPlayVoiceExclusive={handlePlayVoiceExclusive}
             onInterruptAssistantTts={handleInterruptAssistantTts}
+            onPreemptAssistantPlayback={handlePreemptAssistantPlayback}
             onReplayAssistantTts={handleReplayAssistantTts}
+            assistantPlaybackEngaged={assistantPlaybackEngaged}
             bubbleTextStyle={chatBubbleTextStyle}
             voiceDurationTextStyle={chatVoiceDurationStyle}
             readAloudIconSize={chatReadAloudIconSize}
diff --git a/app-expo/src/features/conversation/message-split.ts b/app-expo/src/features/conversation/message-split.ts
index 45b1348..0a4c432 100644
--- a/app-expo/src/features/conversation/message-split.ts
+++ b/app-expo/src/features/conversation/message-split.ts
@@ -50,6 +50,56 @@ export function assistantSegmentMessageId(
   return `${assistantMessageId}_seg_${segmentIndex}`;
 }
 
+const ASSISTANT_SPLIT_LIST_KEY_RE =
+  /^([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})_(?:seg|part)_(\d+)$/i;
+
+/**
+ * 解析展平气泡 `uuid_part_n` 或播放队列 `uuid_seg_n` 的落库 id 与段下标。
+ */
+export function parseAssistantSplitListKey(listKey: string | undefined): {
+  messageId: string;
+  segmentIndex: number;
+} | null {
+  if (!listKey?.length) return null;
+  const m = ASSISTANT_SPLIT_LIST_KEY_RE.exec(listKey);
+  if (m) {
+    return { messageId: m[1]!, segmentIndex: Number(m[2]) };
+  }
+  if (
+    /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i.test(
+      listKey,
+    )
+  ) {
+    return { messageId: listKey, segmentIndex: 0 };
+  }
+  return null;
+}
+
+/** 播放中的 `messageRef.listKey` 是否与当前气泡（含 `_part_` / `_seg_`）为同一段 */
+export function playbackListKeyMatchesBubble(
+  playbackListKey: string | undefined,
+  bubbleListKey: string,
+  messageItemId: string,
+): boolean {
+  if (!playbackListKey?.length) return false;
+  if (playbackListKey === bubbleListKey) return true;
+
+  const playback = parseAssistantSplitListKey(playbackListKey);
+  const bubble =
+    parseAssistantSplitListKey(bubbleListKey) ??
+    parseAssistantSplitListKey(messageItemId);
+  if (playback && bubble) {
+    return (
+      playback.messageId === bubble.messageId &&
+      playback.segmentIndex === bubble.segmentIndex
+    );
+  }
+  if (playbackListKey === messageItemId) {
+    return !playback || playback.segmentIndex === 0;
+  }
+  return false;
+}
+
 /** 历史/已落库消息：拆成非空片段，各渲染为一个气泡 */
 export function splitMessageParts(content: string): string[] {
   return splitToPartsNormalized(String(content ?? ''));
diff --git a/app-expo/src/features/voice/hooks/use-player.ts b/app-expo/src/features/voice/hooks/use-player.ts
index edee04b..d260304 100644
--- a/app-expo/src/features/voice/hooks/use-player.ts
+++ b/app-expo/src/features/voice/hooks/use-player.ts
@@ -3,25 +3,9 @@ import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 
 import { audioFocus } from '@/core/audio/audio-focus';
 
-import type { PlaybackItem, PlayerStatus } from '../types';
+import { parseAssistantSplitListKey } from '@/features/conversation/message-split';
 
-/**
- * `handleTtsSegment` 使用 `assistantSegmentMessageId` → `{uuid}_seg_{n}`；
- * 展平气泡使用 `{uuid}_part_{n}`。同一条落库助手消息上的连续分段应用入队续播，
- * 而不是「暂停后又到一条 tts_auto 就整轨切换成最新」——否则多段朗读只会听到最后一段。
- */
-function parseAssistantSplitListKey(listKey: string | undefined): {
-  messageId: string;
-  segmentIndex: number;
-} | null {
-  if (!listKey) return null;
-  const m =
-    /^([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})_(?:seg|part)_(\d+)$/i.exec(
-      listKey,
-    );
-  if (!m) return null;
-  return { messageId: m[1]!, segmentIndex: Number(m[2]) };
-}
+import type { PlaybackItem, PlayerStatus } from '../types';
 
 function isLaterSegmentOfSameAssistantBubble(
   current: PlaybackItem | null | undefined,
diff --git a/app-expo/tests/features/conversation/message-split.test.ts b/app-expo/tests/features/conversation/message-split.test.ts
index 151595a..9bada8e 100644
--- a/app-expo/tests/features/conversation/message-split.test.ts
+++ b/app-expo/tests/features/conversation/message-split.test.ts
@@ -2,6 +2,8 @@ import {
   assistantSegmentMessageId,
   lastSegmentPreview,
   normalizeAssistantContentForSplit,
+  parseAssistantSplitListKey,
+  playbackListKeyMatchesBubble,
   splitMessageParts,
   splitStreamingSegments,
 } from '@/features/conversation/message-split';
@@ -75,6 +77,28 @@ describe('message-split', () => {
     expect(assistantSegmentMessageId('uuid-a', 1)).toBe('uuid-a_seg_1');
   });
 
+  it('playbackListKeyMatchesBubble aligns seg playback with part listKey', () => {
+    const uuid = '78b32c06-d2f9-453b-9cc4-354e68fbcb2d';
+    expect(
+      playbackListKeyMatchesBubble(
+        `${uuid}_seg_1`,
+        `${uuid}_part_1`,
+        uuid,
+      ),
+    ).toBe(true);
+    expect(
+      playbackListKeyMatchesBubble(
+        `${uuid}_seg_0`,
+        `${uuid}_part_1`,
+        uuid,
+      ),
+    ).toBe(false);
+    expect(parseAssistantSplitListKey(`${uuid}_part_0`)).toEqual({
+      messageId: uuid,
+      segmentIndex: 0,
+    });
+  });
+
   it('normalizeAssistantContentForSplit maps fullwidth brackets', () => {
     expect(normalizeAssistantContentForSplit('［x］')).toBe('[x]');
     expect(normalizeAssistantContentForSplit('【x】')).toBe('[x]');