Fix task status stuck at 'running': use new DB session in thread, add frontend auto-polling

platform/backend/app/api/tasks.py

@@ -227,25 +227,34 @@ def run_creator_task(
     from ..core.generator import run_creator
 
     def _run():
+        from ..database import SessionLocal
+        from datetime import datetime, timezone
+        new_db = SessionLocal()
         try:
             result = run_creator(topic_id)
-            finished = datetime.now(timezone.utc)
-            task.status = "completed"
-            task.finished_at = finished
-            task.progress = 100
-            task.message = "创作完成"
-            task.result_data = result or {}
-            if task.started_at:
-                task.duration = int((finished - task.started_at).total_seconds())
-            db.commit()
+            new_task = new_db.query(ContentTask).filter(ContentTask.task_id == task_id).first()
+            if new_task:
+                finished = datetime.now(timezone.utc)
+                new_task.status = "completed"
+                new_task.finished_at = finished
+                new_task.progress = 100
+                new_task.message = "创作完成"
+                new_task.result_data = result or {}
+                if new_task.started_at:
+                    new_task.duration = int((finished - new_task.started_at).total_seconds())
+                new_db.commit()
         except Exception as e:
-            finished = datetime.now(timezone.utc)
-            task.status = "failed"
-            task.finished_at = finished
-            task.error_msg = str(e)
-            if task.started_at:
-                task.duration = int((finished - task.started_at).total_seconds())
-            db.commit()
+            new_task = new_db.query(ContentTask).filter(ContentTask.task_id == task_id).first()
+            if new_task:
+                finished = datetime.now(timezone.utc)
+                new_task.status = "failed"
+                new_task.finished_at = finished
+                new_task.error_msg = str(e)
+                if new_task.started_at:
+                    new_task.duration = int((finished - new_task.started_at).total_seconds())
+                new_db.commit()
+        finally:
+            new_db.close()
 
     thread = threading.Thread(target=_run)
     thread.start()