fix(api): 修复缓存状态判断逻辑

- fetch_data_with_ttl 返回 (data, is_cached) 元组
- 修复 cached 字段始终为 false 的问题
- 批量接口适配新的返回格式

core/datasource/flask_server.py

@@ -137,14 +137,17 @@ def _fetch_data_cached(code: str, start: str, end: str, retry: int) -> Optional[
         return json.dumps({"error": str(e)})
 
 
-def fetch_data_with_ttl(code: str, start: str, end: str, retry: int = 3, nocache: bool = False) -> Optional[Dict]:
+def fetch_data_with_ttl(code: str, start: str, end: str, retry: int = 3, nocache: bool = False) -> tuple[Optional[Dict], bool]:
     """
     获取数据，支持TTL缓存
+    
+    Returns:
+        (data, is_cached): 数据和是否命中缓存
     """
     if nocache:
         # 直接获取，不使用缓存
         result_json = _fetch_data_cached.__wrapped__(code, start, end, retry)
-        return json.loads(result_json) if result_json else None
+        return (json.loads(result_json) if result_json else None, False)
     
     # 使用缓存
     cache_key = (code, start, end, retry)
@@ -154,7 +157,7 @@ def fetch_data_with_ttl(code: str, start: str, end: str, retry: int = 3, nocache
         if cache_key in fetch_data_with_ttl._ttl_cache:
             entry = fetch_data_with_ttl._ttl_cache[cache_key]
             if not entry.is_expired():
-                return entry.data
+                return entry.data, True
             # 过期，删除
             del fetch_data_with_ttl._ttl_cache[cache_key]
     else:
@@ -164,14 +167,14 @@ def fetch_data_with_ttl(code: str, start: str, end: str, retry: int = 3, nocache
     result_json = _fetch_data_cached(code, start, end, retry)
     
     if result_json is None:
-        return None
+        return None, False
     
     result = json.loads(result_json)
     
     # 存入TTL缓存
     fetch_data_with_ttl._ttl_cache[cache_key] = TimedCacheEntry(result)
     
-    return result
+    return result, False
 
 
 def clear_data_cache():
@@ -422,7 +425,7 @@ def get_ohlcv():
         retry_count = 3
     
     # 使用缓存获取数据
-    result = fetch_data_with_ttl(code, start, end, retry_count, nocache)
+    result, is_cached = fetch_data_with_ttl(code, start, end, retry_count, nocache)
     
     if result is None:
         return jsonify({
@@ -443,7 +446,7 @@ def get_ohlcv():
         }), 500
     
     # 添加缓存状态
-    result['cached'] = not nocache and _fetch_data_cached.cache_info().hits > 0
+    result['cached'] = is_cached
     
     return jsonify(result)
 
@@ -520,7 +523,7 @@ def batch_ohlcv():
             for code in codes:
                 try:
                     # 使用缓存获取数据
-                    result = fetch_data_with_ttl(code, start, end, retry, nocache=False)
+                    result, _ = fetch_data_with_ttl(code, start, end, retry, nocache=False)
                     
                     if result is not None and "error" not in result:
                         results[code] = result