diff --git a/src/api/blackboard_routes.py b/src/api/blackboard_routes.py
index 96660a0..0698584 100644
--- a/src/api/blackboard_routes.py
+++ b/src/api/blackboard_routes.py
@@ -74,11 +74,15 @@ async def create_task(project_id: str, body: Dict[str, Any]):
         prefix = re.sub(r'[^a-z0-9]', '-', project_id.lower()).strip('-')[:20]
         date_str = datetime.now().strftime('%Y%m%d')
         # seq: 查当前项目最大 seq
+        import sqlite3
+        db_path = get_data_root() / project_id / "blackboard.db"
         try:
-            max_id_row = bb._conn.execute(
+            conn = sqlite3.connect(str(db_path), timeout=5)
+            max_id_row = conn.execute(
                 "SELECT id FROM tasks WHERE id LIKE ? ORDER BY id DESC LIMIT 1",
                 (f"{prefix}-{date_str}-%",)
             ).fetchone()
+            conn.close()
             seq = int(max_id_row[0].split('-')[-1]) + 1 if max_id_row else 1
         except Exception:
             seq = 1