fix: merge streamed tail text into the previous assistant bubble

Keep late-arriving streamed punctuation attached to the active assistant reply so desktop chat no longer renders the final character as its own bubble.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

desktop/src/stores/chatStore.test.ts

@@ -385,6 +385,95 @@ describe('chatStore history mapping', () => {
     })
   })
 
+  it('merges trailing streamed punctuation into the previous assistant bubble on completion', () => {
+    useChatStore.setState({
+      sessions: {
+        [TEST_SESSION_ID]: {
+          messages: [
+            {
+              id: 'assistant-1',
+              type: 'assistant_text',
+              content: '你好',
+              timestamp: 1,
+            },
+          ],
+          chatState: 'streaming',
+          connectionState: 'connected',
+          streamingText: '。',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+
+    useChatStore.getState().handleServerMessage(TEST_SESSION_ID, {
+      type: 'message_complete',
+      usage: { input_tokens: 1, output_tokens: 1 },
+    })
+
+    expect(useChatStore.getState().sessions[TEST_SESSION_ID]?.messages).toMatchObject([
+      {
+        type: 'assistant_text',
+        content: '你好。',
+      },
+    ])
+  })
+
+  it('merges streamed tail text when status changes out of streaming', () => {
+    useChatStore.setState({
+      sessions: {
+        [TEST_SESSION_ID]: {
+          messages: [
+            {
+              id: 'assistant-1',
+              type: 'assistant_text',
+              content: '分析完成',
+              timestamp: 1,
+            },
+          ],
+          chatState: 'streaming',
+          connectionState: 'connected',
+          streamingText: '。',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+
+    useChatStore.getState().handleServerMessage(TEST_SESSION_ID, {
+      type: 'status',
+      state: 'idle',
+      tokens: 3,
+    })
+
+    expect(useChatStore.getState().sessions[TEST_SESSION_ID]?.messages).toMatchObject([
+      {
+        type: 'assistant_text',
+        content: '分析完成。',
+      },
+    ])
+  })
+
   it('flushes the previous assistant draft before starting a new user turn', () => {
     useChatStore.setState({
       sessions: {

desktop/src/stores/chatStore.ts

@@ -108,6 +108,29 @@ const pendingTaskToolUseIds = new Set<string>()
 let msgCounter = 0
 const nextId = () => `msg-${++msgCounter}-${Date.now()}`
 
+function appendAssistantTextMessage(messages: UIMessage[], content: string): UIMessage[] {
+  if (!content) return messages
+  const last = messages[messages.length - 1]
+  if (last?.type === 'assistant_text') {
+    return [
+      ...messages.slice(0, -1),
+      {
+        ...last,
+        content: last.content + content,
+      },
+    ]
+  }
+  return [
+    ...messages,
+    {
+      id: nextId(),
+      type: 'assistant_text',
+      content,
+      timestamp: Date.now(),
+    },
+  ]
+}
+
 // Streaming throttle for content_delta
 let pendingDelta = ''
 let flushTimer: ReturnType<typeof setTimeout> | null = null
@@ -218,15 +241,7 @@ export const useChatStore = create<ChatStore>((set, get) => ({
       const pendingAssistantText = `${session.streamingText}${bufferedDelta}`.trim()
 
       const newMessages = pendingAssistantText
-        ? [
+        ? appendAssistantTextMessage(session.messages, pendingAssistantText)
-            ...session.messages,
-            {
-              id: nextId(),
-              type: 'assistant_text' as const,
-              content: pendingAssistantText,
-              timestamp: Date.now(),
-            },
-          ]
         : [...session.messages]
       if (!isMemberSession && allTasksDone) {
         newMessages.push({
@@ -392,6 +407,16 @@ export const useChatStore = create<ChatStore>((set, get) => ({
         break
 
       case 'status':
+        // Flush any pending delta before processing status change
+        if (flushTimer && msg.state !== 'streaming') {
+          clearTimeout(flushTimer)
+          flushTimer = null
+        }
+        if (pendingDelta && msg.state !== 'streaming') {
+          const deltaText = pendingDelta
+          pendingDelta = ''
+          set((s) => ({ sessions: updateSessionIn(s.sessions, sessionId, (sess) => ({ streamingText: sess.streamingText + deltaText })) }))
+        }
         update((session) => {
           const pendingText = session.streamingText.trim()
           const shouldFlush = pendingText && session.chatState === 'streaming' && msg.state !== 'streaming'
@@ -401,7 +426,7 @@ export const useChatStore = create<ChatStore>((set, get) => ({
             ...(msg.tokens ? { tokenUsage: { ...session.tokenUsage, output_tokens: msg.tokens } } : {}),
             ...(msg.state === 'idle' ? { activeThinkingId: null, statusVerb: '' } : {}),
             ...(shouldFlush ? {
-              messages: [...session.messages, { id: nextId(), type: 'assistant_text' as const, content: pendingText, timestamp: Date.now() }],
+              messages: appendAssistantTextMessage(session.messages, pendingText),
               streamingText: '',
             } : {}),
           }
@@ -423,7 +448,7 @@ export const useChatStore = create<ChatStore>((set, get) => ({
         const pendingText = session.streamingText.trim()
         if (pendingText) {
           update((s) => ({
-            messages: [...s.messages, { id: nextId(), type: 'assistant_text' as const, content: pendingText, timestamp: Date.now() }],
+            messages: appendAssistantTextMessage(s.messages, pendingText),
             streamingText: '',
           }))
         }
@@ -460,7 +485,7 @@ export const useChatStore = create<ChatStore>((set, get) => ({
         update((s) => {
           const pendingText = s.streamingText.trim()
           const base = pendingText
-            ? [...s.messages, { id: nextId(), type: 'assistant_text' as const, content: pendingText, timestamp: Date.now() }]
+            ? appendAssistantTextMessage(s.messages, pendingText)
             : s.messages
           const last = base[base.length - 1]
           if (last && last.type === 'thinking') {
@@ -553,13 +578,25 @@ export const useChatStore = create<ChatStore>((set, get) => ({
         break
 
       case 'message_complete': {
+        // Flush any pending delta before processing complete
+        if (flushTimer) {
+          clearTimeout(flushTimer)
+          flushTimer = null
+        }
+        if (pendingDelta) {
+          const deltaText = pendingDelta
+          pendingDelta = ''
+          set((s) => ({ sessions: updateSessionIn(s.sessions, sessionId, (sess) => ({ streamingText: sess.streamingText + deltaText })) }))
+        }
         const session = get().sessions[sessionId]
         if (!session) break
-        const text = session.streamingText
+        const text = session.streamingText.trim()
         if (text) {
-          update((s) => ({
+          set((s) => ({
-            messages: [...s.messages, { id: nextId(), type: 'assistant_text', content: text, timestamp: Date.now() }],
+            sessions: updateSessionIn(s.sessions, sessionId, (sess) => ({
-            streamingText: '',
+              messages: appendAssistantTextMessage(sess.messages, text),
+              streamingText: '',
+            })),
           }))
         }
         if (session.elapsedTimer) clearInterval(session.elapsedTimer)
@@ -579,7 +616,7 @@ export const useChatStore = create<ChatStore>((set, get) => ({
           const pendingText = s.streamingText.trim()
           const newMessages = [...s.messages]
           if (pendingText) {
-            newMessages.push({ id: nextId(), type: 'assistant_text' as const, content: pendingText, timestamp: Date.now() })
+            newMessages.splice(0, newMessages.length, ...appendAssistantTextMessage(newMessages, pendingText))
           }
           newMessages.push({ id: nextId(), type: 'error', message: msg.message, code: msg.code, timestamp: Date.now() })
           return {