Fix live activity streaming and replay summary

backend/api/server.py

@@ -1901,7 +1901,14 @@ def create_app(state: AgentState) -> FastAPI:
                     break
                 yield json.dumps(item, ensure_ascii=False) + '\n'
 
-        return StreamingResponse(generate(), media_type='application/x-ndjson')
+        return StreamingResponse(
+            generate(),
+            media_type='application/x-ndjson',
+            headers={
+                'Cache-Control': 'no-cache, no-transform',
+                'X-Accel-Buffering': 'no',
+            },
+        )
 
     @app.post('/api/clear')
     async def clear_state(account_id: str | None = None) -> dict[str, Any]:
@@ -2117,12 +2124,17 @@ def _interrupted_session_message(status: str) -> str:
 
 def _runtime_event_stage(event: dict[str, object]) -> str:
     event_type = event.get('type')
+    if event_type == 'content_delta':
+        return ''
     if event_type == 'tool_start':
         stage_note = str(event.get('assistant_content') or '').strip()
         if stage_note.startswith(('进度：', '进度:')):
             return stage_note
         tool_name = str(event.get('tool_name') or '').strip()
         return f'调用工具 {tool_name}' if tool_name else '正在调用工具'
+    if event_type == 'tool_delta':
+        tool_name = str(event.get('tool_name') or '').strip()
+        return f'{tool_name} 输出中' if tool_name else '工具输出中'
     if event_type == 'tool_result':
         tool_name = str(event.get('tool_name') or '').strip()
         return f'工具完成 {tool_name}' if tool_name else '工具调用完成'
@@ -2149,7 +2161,9 @@ def _runtime_event_stage(event: dict[str, object]) -> str:
 _RUN_EVENT_TYPES = {
     'run_queued',
     'run_started',
+    'content_delta',
     'tool_start',
+    'tool_delta',
     'tool_result',
     'final_text_start',
     'final_text_end',
@@ -2175,8 +2189,10 @@ def _normalize_run_event(event: dict[str, object]) -> dict[str, Any] | None:
         'tool_name',
         'tool_call_id',
         'arguments',
+        'delta',
         'assistant_content',
         'message_id',
+        'stream',
         'ok',
         'metadata',
         'reason',