fix(desktop): collapse duplicate thinking blocks in history mapping

Subagent transcripts persist streamed thinking snapshots, and the
history-mapping path pushed every block verbatim, so the subagent run
page rendered long runs of repeated empty "thought" bubbles. Give the
history path the same guards as the streaming path: drop blank blocks,
drop verbatim replays, replace prefix-growth snapshots, and merge
adjacent blocks while keeping deterministic ids for stable React keys.

desktop/src/stores/chatStore.test.ts

@@ -484,6 +484,69 @@ describe('chatStore history mapping', () => {
     expect(mapped[3]).toMatchObject({ parentToolUseId: 'agent-1' })
   })
 
+  it('collapses replayed and blank thinking blocks from history mapping', () => {
+    const messages: MessageEntry[] = [
+      {
+        id: 'assistant-snap-1',
+        type: 'assistant',
+        timestamp: '2026-04-06T00:00:00.000Z',
+        content: [{ type: 'thinking', thinking: 'plan the fix' }],
+      },
+      // 流式快照整块重发：逐字相同，应丢弃
+      {
+        id: 'assistant-snap-2',
+        type: 'assistant',
+        timestamp: '2026-04-06T00:00:01.000Z',
+        content: [{ type: 'thinking', thinking: 'plan the fix' }],
+      },
+      // 流式快照前缀增长：应替换为更全的新块而非追加
+      {
+        id: 'assistant-snap-3',
+        type: 'assistant',
+        timestamp: '2026-04-06T00:00:02.000Z',
+        content: [{ type: 'thinking', thinking: 'plan the fix carefully' }],
+      },
+      // 纯空白块：不应产生空壳气泡
+      {
+        id: 'assistant-blank',
+        type: 'assistant',
+        timestamp: '2026-04-06T00:00:03.000Z',
+        content: [{ type: 'thinking', thinking: '   \n  ' }],
+      },
+      // 相邻但内容无关的思考：合并为一个气泡
+      {
+        id: 'assistant-more',
+        type: 'assistant',
+        timestamp: '2026-04-06T00:00:04.000Z',
+        content: [{ type: 'thinking', thinking: 'then run tests' }],
+      },
+      // 被工具打断后的新思考：保持独立
+      {
+        id: 'assistant-tools',
+        type: 'assistant',
+        timestamp: '2026-04-06T00:00:05.000Z',
+        content: [
+          { type: 'tool_use', name: 'Bash', id: 'bash-1', input: { command: 'pwd' } },
+        ],
+      },
+      {
+        id: 'assistant-final',
+        type: 'assistant',
+        timestamp: '2026-04-06T00:00:06.000Z',
+        content: [{ type: 'thinking', thinking: 'tests pass' }],
+      },
+    ]
+
+    const mapped = mapHistoryMessagesToUiMessages(messages)
+
+    expect(mapped.map((message) => message.type)).toEqual(['thinking', 'tool_use', 'thinking'])
+    expect(mapped[0]).toMatchObject({
+      id: 'assistant-snap-1-block-0',
+      content: 'plan the fix carefullythen run tests',
+    })
+    expect(mapped[2]).toMatchObject({ id: 'assistant-final-block-0', content: 'tests pass' })
+  })
+
   it('maps AskUserQuestion transcript answers from toolUseResult metadata', () => {
     const messages: MessageEntry[] = [
       {

desktop/src/stores/chatStore.ts

@@ -4150,6 +4150,32 @@ function pushAssistantHistoryText(
   })
 }
 
+function pushAssistantHistoryThinking(
+  messages: UIMessage[],
+  id: string,
+  content: string,
+  timestamp: number,
+): void {
+  // 与流式路径（case 'thinking'）保持同等防护：纯空白块不产生空壳气泡。
+  if (!content.trim()) return
+
+  const last = messages[messages.length - 1]
+  if (last?.type === 'thinking') {
+    // 流式落盘的快照会让同一段思考在 jsonl 里以"整块重发"或"前缀增长"的
+    // 形态重复出现，逐字相同直接丢弃，前缀包含则用更全的新块替换旧块。
+    // 合并时保留首个块的确定性 id，保证轮询重映射时 React key 稳定。
+    if (last.content === content) return
+    if (content.startsWith(last.content)) {
+      last.content = content
+      return
+    }
+    last.content += content
+    return
+  }
+
+  messages.push({ id, type: 'thinking', content, timestamp })
+}
+
 type HistoryMappingOptions = {
   includeTeammateMessages?: boolean
 }
@@ -4767,7 +4793,7 @@ export function mapHistoryMessagesToUiMessages(
     }
     if ((msg.type === 'assistant' || msg.type === 'tool_use') && Array.isArray(msg.content)) {
       for (const [blockIndex, block] of (msg.content as AssistantHistoryBlock[]).entries()) {
-        if (block.type === 'thinking' && block.thinking) uiMessages.push({ id: `${msg.id}-block-${blockIndex}`, type: 'thinking', content: block.thinking, timestamp })
+        if (block.type === 'thinking' && block.thinking) pushAssistantHistoryThinking(uiMessages, `${msg.id}-block-${blockIndex}`, block.thinking, timestamp)
         else if (block.type === 'text' && block.text) {
           pushAssistantHistoryText(uiMessages, block.text, timestamp, msg.model, msg.id || undefined)
         }