fix: ensure cover title matches current video title

- Add task_id parameter to extract_and_upload_cover_frames
- Change storage key from covers/{plan_id}/frame_{i}.jpg to covers/{plan_id}/{task_id}/frame_{i}.jpg
- Clear cover field in plan.config when title changes in _writeback_edit_plan_config
- Pass job_id as task_id in render_adapter.py

This fixes the issue where modifying the title and generating a new video
would still show the old title on the cover.

apps/api/app/api/routes/generation_tasks.py

@@ -169,8 +169,22 @@ def _writeback_edit_plan_config(
         current_config = plan_model.config if isinstance(plan_model.config, dict) else {}
         merged = dict(current_config)
         merged["generation_task_id"] = task_id
+        
+        # 检查标题是否发生变化，如果变化则清除 cover 字段强制重新生成封面
         if title_config:
+            old_title_config = merged.get("title_config", {}) or {}
+            old_title_text = (old_title_config.get("text") or "").strip()
+            new_title_text = (title_config.get("text") or "").strip()
+            if old_title_text != new_title_text:
+                # 标题变化，清除旧封面
+                if "cover" in merged:
+                    del merged["cover"]
+                    logger.info(
+                        "[生成任务] 标题变化，清除旧封面: plan_id=%s old_title=%s new_title=%s",
+                        plan_id, old_title_text, new_title_text,
+                    )
             merged["title_config"] = title_config
+        
         plan_model.config = merged
         db.commit()
         logger.info(

apps/worker/video_processing/render_adapter.py

@@ -598,7 +598,7 @@ class RenderAdapter:
             # 抽帧天然带标题，因此这里传空字符串，避免 Pillow 二次叠加导致重影。
             # Pillow 叠加仅用于 API 从源素材抽帧（源素材本身无标题）的兜底场景。
             cover_candidates = extract_and_upload_cover_frames(
-                str(result.output_path), plan_id, num_frames=3, title_text=""
+                str(result.output_path), plan_id, task_id=job_id, num_frames=3, title_text=""
             )
             if cover_candidates:
                 logger.info(

apps/worker/video_processing/thumbnail_generator.py

@@ -278,6 +278,7 @@ def extract_and_upload_cover_frames(
     video_path: str,
     plan_id: str,
     *,
+    task_id: str = "",
     num_frames: int = 3,
     title_text: str = "",
     title_color: str = "#ffffff",
@@ -291,6 +292,7 @@ def extract_and_upload_cover_frames(
     Args:
         video_path: 视频文件路径
         plan_id: 编辑计划 ID（用于生成 storage key）
+        task_id: 任务 ID（用于生成独立的 storage key，避免标题变更时封面冲突）
         num_frames: 抽取帧数（默认 3）
         title_text: 标题文字；非空时用 Pillow 叠加到每帧。
             从已渲染视频抽帧时通常传空（标题已烧录）；从源素材抽帧时传标题。
@@ -338,7 +340,7 @@ def extract_and_upload_cover_frames(
                         font_size=title_font_size,
                     )
 
-                storage_key = f"covers/{plan_id}/mediakit_frame_{i}.jpg"
+                storage_key = f"covers/{plan_id}/{task_id}/mediakit_frame_{i}.jpg"
                 url = upload_to_oss(tmp.name, storage_key)
                 if url:
                     seek_time = frame.get("timestamp", 0.0)
@@ -377,7 +379,7 @@ def extract_and_upload_cover_frames(
                     position=title_position,
                     font_size=title_font_size,
                 )
-            storage_key = f"covers/{plan_id}/frame_{i}.jpg"
+            storage_key = f"covers/{plan_id}/{task_id}/frame_{i}.jpg"
             url = upload_to_oss(frame_path, storage_key)
             if url:
                 seek_time = max(0.5, duration * ratio) if duration > 0 else 0.0