fix(i18n): pass locale to background threads via thread-local storage

Background threads (graph building, simulation prep, report generation,
profile generation) now inherit the requesting user's locale preference.
Previously these fell back to 'zh' because Flask request context was
unavailable in spawned threads.

backend/app/services/graph_builder.py

@@ -17,7 +17,7 @@ from ..config import Config
 from ..models.task import TaskManager, TaskStatus
 from ..utils.zep_paging import fetch_all_nodes, fetch_all_edges
 from .text_processor import TextProcessor
-from ..utils.locale import t
+from ..utils.locale import t, get_locale, set_locale
 
 
 @dataclass
@@ -84,10 +84,13 @@ class GraphBuilderService:
             }
         )
         
+        # Capture locale before spawning background thread
+        current_locale = get_locale()
+
         # 在后台线程中执行构建
         thread = threading.Thread(
             target=self._build_graph_worker,
-            args=(task_id, text, ontology, graph_name, chunk_size, chunk_overlap, batch_size)
+            args=(task_id, text, ontology, graph_name, chunk_size, chunk_overlap, batch_size, current_locale)
         )
         thread.daemon = True
         thread.start()
@@ -102,9 +105,11 @@ class GraphBuilderService:
         graph_name: str,
         chunk_size: int,
         chunk_overlap: int,
-        batch_size: int
+        batch_size: int,
+        locale: str = 'zh'
     ):
         """图谱构建工作线程"""
+        set_locale(locale)
         try:
             self.task_manager.update_task(
                 task_id,

backend/app/services/oasis_profile_generator.py

@@ -20,7 +20,7 @@ from zep_cloud.client import Zep
 
 from ..config import Config
 from ..utils.logger import get_logger
-from ..utils.locale import get_language_instruction, t
+from ..utils.locale import get_language_instruction, get_locale, set_locale, t
 from .zep_entity_reader import EntityNode, ZepEntityReader
 
 logger = get_logger('mirofish.oasis_profile')
@@ -916,8 +916,12 @@ class OasisProfileGenerator:
                 except Exception as e:
                     logger.warning(f"实时保存 profiles 失败: {e}")
         
+        # Capture locale before spawning thread pool workers
+        current_locale = get_locale()
+
         def generate_single_profile(idx: int, entity: EntityNode) -> tuple:
             """生成单个profile的工作函数"""
+            set_locale(current_locale)
             entity_type = entity.get_entity_type() or "Entity"
             
             try:

backend/app/services/simulation_runner.py

@@ -20,6 +20,7 @@ from queue import Queue
 
 from ..config import Config
 from ..utils.logger import get_logger
+from ..utils.locale import get_locale, set_locale
 from .zep_graph_memory_updater import ZepGraphMemoryManager
 from .simulation_ipc import SimulationIPCClient, CommandType, IPCResponse
 
@@ -455,10 +456,13 @@ class SimulationRunner:
             cls._processes[simulation_id] = process
             cls._save_run_state(state)
             
+            # Capture locale before spawning monitor thread
+            current_locale = get_locale()
+
             # 启动监控线程
             monitor_thread = threading.Thread(
                 target=cls._monitor_simulation,
-                args=(simulation_id,),
+                args=(simulation_id, current_locale),
                 daemon=True
             )
             monitor_thread.start()
@@ -475,8 +479,9 @@ class SimulationRunner:
         return state
     
     @classmethod
-    def _monitor_simulation(cls, simulation_id: str):
+    def _monitor_simulation(cls, simulation_id: str, locale: str = 'zh'):
         """监控模拟进程，解析动作日志"""
+        set_locale(locale)
         sim_dir = os.path.join(cls.RUN_STATE_DIR, simulation_id)
         
         # 新的日志结构：分平台的动作日志

backend/app/services/zep_graph_memory_updater.py

@@ -16,6 +16,7 @@ from zep_cloud.client import Zep
 
 from ..config import Config
 from ..utils.logger import get_logger
+from ..utils.locale import get_locale, set_locale
 
 logger = get_logger('mirofish.zep_graph_memory_updater')
 
@@ -275,10 +276,14 @@ class ZepGraphMemoryUpdater:
         """启动后台工作线程"""
         if self._running:
             return
-        
+
+        # Capture locale before spawning background thread
+        current_locale = get_locale()
+
         self._running = True
         self._worker_thread = threading.Thread(
             target=self._worker_loop,
+            args=(current_locale,),
             daemon=True,
             name=f"ZepMemoryUpdater-{self.graph_id[:8]}"
         )
@@ -356,8 +361,9 @@ class ZepGraphMemoryUpdater:
         
         self.add_activity(activity)
     
-    def _worker_loop(self):
+    def _worker_loop(self, locale: str = 'zh'):
         """后台工作循环 - 按平台批量发送活动到Zep"""
+        set_locale(locale)
         while self._running or not self._activity_queue.empty():
             try:
                 # 尝试从队列获取活动（超时1秒）