fix(worker+api): resolve batch title race + auto-queue pending tasks (#2098)

Two batch-rendering bugs found from staging logs (6-video batch 17:30-17:43):

Bug A (P1) — title_config race when same plan renders concurrently:
  _sync_task_config_to_plan wrote each task's title_config/bgm/resolution
  to the shared plan.config row, then RenderAdapter.render_plan read back
  from plan.config during rendering. If two tasks sharing the same plan
  (e.g. batch retry, preview+render, retry+new) ran concurrently, Task B's
  write could overwrite Task A's title before Task A's ffmpeg read it,
  producing videos with the wrong title text/style.

  Fix: stop mutating plan.config in the worker render path. Introduce
  task_config_override threading through render_plan / _do_render /
  UnifiedRenderService; URS reads config via _effective_config() which
  does a deep-copy plan.config merged with per-task override (title/bgm/
  export). _build_task_config_override builds the override dict (with
  field-name normalization: font_size→size, font_color→color) from
  task_info, and _download_voice_for_task handles voiceover download
  independently. plan.config is left as-authored by the API writeback;
  concurrent tasks no longer race on it.

  Files:
  - apps/worker/video_processing/unified_render_service.py: add
    override_config param + _cfg_section/_effective_config helpers;
    replace all render-time self.plan.config reads (title/subtitle/bgm/
    export/TTS) with _effective_config().
  - apps/worker/video_processing/render_adapter.py: render_plan/_do_render/
    _prepare_bgm accept task_config_override, merge into bgm/export reads,
    forward to URS.
  - apps/worker/worker_app/tasks/generation.py: replace
    _sync_task_config_to_plan (which wrote plan.config) with
    _build_task_config_override + _download_voice_for_task; pass
    task_config_override to render_plan.

Bug B (P0) — USER_PENDING_LIMIT=3 returns HTTP 429, blocks batch submit:
  Pre-check in create_generation_task rejected the whole batch with 429
  USER_QUEUE_FULL once user had ≥3 pending tasks; UI showed 'wait ~4 min'
  and prevented any more submissions. Users expect to submit a batch of
  6 and have them queue naturally (worker concurrency=2).

  Fix:
  - USER_PENDING_LIMIT 3→20 (soft cap for abuse protection, supports
    typical batch sizes of 6-10 with headroom).
  - Remove user-level 429 rejection from pre-check, retry endpoint,
    single-task confirm endpoint, and safe_enqueue (user path now logs
    a warning and continues to enqueue). Global GLOBAL_PENDING_LIMIT=20
    is retained as a hard 503 system-busy guard.
  - safe_enqueue post-enqueue check: user-over only logs, does not
    fail the task or raise.
  - Batch loop UserPendingLimitExceeded except branch now treats it as
    a successful enqueue (should not trigger in practice).

  Files:
  - apps/api/app/core/task_enqueue.py: limit 3→20; user checks log-only.
  - apps/api/app/api/routes/generation_tasks.py: remove user pre-check
    429; soften retry/single/batch except branches.

Stacked on PR #2095/#2097 which already fixed title baseline/width-scaling
and default-constant alignment with CPU video_filter_builder.

Tests:
- tests/unit/test_gpu_direct_pipeline.py: 30 passed
- tests/unit/test_render_adapter_pure.py: 18 passed
- ruff check/format clean; py_compile clean

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

@@ -7,7 +7,6 @@ from app.auth import AuthenticatedUser, get_current_user
 from app.core.storage import OSSStorageService, get_storage_service
 from app.core.task_enqueue import (
     GLOBAL_PENDING_LIMIT,
-    USER_PENDING_LIMIT,
     GlobalQueueFull,
     UserPendingLimitExceeded,
     build_rate_limit_detail,
@@ -50,12 +49,98 @@ from packages.domain.smart_match import smart_select_assets
 # #2035：文案关键词 → 素材分类 映射表（用于 smart_match category_match 维度）
 # AssetClassification 枚举: scenic / product / person / animal / food / tech / sport / music / other
 _CATEGORY_KEYWORDS: dict[str, set[str]] = {
-    "scenic": {"风景", "自然", "山水", "大海", "天空", "日落", "日出", "森林", "城市", "建筑", "夜景", "街道", "公园", "景区", "旅行", "旅游", "户外"},
-    "product": {"产品", "商品", "展示", "演示", "开箱", "评测", "好物", "推荐", "种草", "购物", "电商", "带货", "品牌", "广告", "包装"},
-    "person": {"人物", "人物采访", "对话", "说话", "讲解", "演讲", "采访", "聊天", "开会", "工作", "办公室", "团队", "员工", "老板", "女性", "男性", "美女", "帅哥"},
+    "scenic": {
+        "风景",
+        "自然",
+        "山水",
+        "大海",
+        "天空",
+        "日落",
+        "日出",
+        "森林",
+        "城市",
+        "建筑",
+        "夜景",
+        "街道",
+        "公园",
+        "景区",
+        "旅行",
+        "旅游",
+        "户外",
+    },
+    "product": {
+        "产品",
+        "商品",
+        "展示",
+        "演示",
+        "开箱",
+        "评测",
+        "好物",
+        "推荐",
+        "种草",
+        "购物",
+        "电商",
+        "带货",
+        "品牌",
+        "广告",
+        "包装",
+    },
+    "person": {
+        "人物",
+        "人物采访",
+        "对话",
+        "说话",
+        "讲解",
+        "演讲",
+        "采访",
+        "聊天",
+        "开会",
+        "工作",
+        "办公室",
+        "团队",
+        "员工",
+        "老板",
+        "女性",
+        "男性",
+        "美女",
+        "帅哥",
+    },
     "animal": {"动物", "宠物", "狗", "猫", "鸟", "鱼", "马", "牛", "羊", "野生动物", "动物园"},
-    "food": {"美食", "食物", "餐饮", "餐厅", "做饭", "烹饪", "厨房", "菜品", "饮料", "水果", "甜点", "蛋糕", "咖啡", "茶", "零食", "吃"},
-    "tech": {"科技", "数码", "电脑", "手机", "屏幕", "软件", "APP", "互联网", "AI", "人工智能", "机器人", "办公", "程序员", "代码", "屏幕录制"},
+    "food": {
+        "美食",
+        "食物",
+        "餐饮",
+        "餐厅",
+        "做饭",
+        "烹饪",
+        "厨房",
+        "菜品",
+        "饮料",
+        "水果",
+        "甜点",
+        "蛋糕",
+        "咖啡",
+        "茶",
+        "零食",
+        "吃",
+    },
+    "tech": {
+        "科技",
+        "数码",
+        "电脑",
+        "手机",
+        "屏幕",
+        "软件",
+        "APP",
+        "互联网",
+        "AI",
+        "人工智能",
+        "机器人",
+        "办公",
+        "程序员",
+        "代码",
+        "屏幕录制",
+    },
     "sport": {"运动", "健身", "跑步", "篮球", "足球", "游泳", "瑜伽", "户外", "锻炼", "体育", "比赛", "球场"},
     "music": {"音乐", "歌曲", "演唱会", "乐器", "唱歌", "跳舞", "舞蹈", "MV", "演出", "乐队", "钢琴", "吉他", "节奏"},
 }
@@ -77,6 +162,7 @@ def _infer_expected_categories(script_tags: set[str] | None) -> set[str] | None:
                 break
     return matched or None
 
+
 from packages.middleware.points_gate import points_gate
 
 logger = logging.getLogger(__name__)
@@ -193,10 +279,13 @@ def _select_assets_from_library(
     # #2035：加载片段级 AI 标签，供叙事模式 AI 加权和 smart 模式语义匹配使用。
     # 失败降级为空（不影响选片主流程）。
     clip_ai_tags_by_asset: dict[str, list[dict]] = {}
-    ai_tags_by_asset: dict[str, dict] = {}  # asset_id → 聚合后的 ai_tags dict（取首个有 has_text 的片段；合并 scene/objects/action 去重）
+    ai_tags_by_asset: dict[
+        str, dict
+    ] = {}  # asset_id → 聚合后的 ai_tags dict（取首个有 has_text 的片段；合并 scene/objects/action 去重）
     try:
         if db is not None:
             from packages.adapters.sqlalchemy_impl.models import AssetAtomClipModel
+
             ready_ids = [a.id for a in ready_video_assets]
             clip_rows = (
                 db.query(AssetAtomClipModel.asset_id, AssetAtomClipModel.ai_tags)
@@ -594,21 +683,13 @@ def create_generation_task(
     # 同批次任务共享 batch_id，用于视频查重时批次内比对
     batch_id = uuid.uuid4().hex if count > 1 else ""
 
-    # 预检查：批量提交前先看会不会超限，避免建一半才拒
+    # 预检查（Bug B #2098）：只保留全局 503 保护，用户级不再硬拒 429；
+    # 超额任务直接入队等待 worker 自然消费，前端展示排队位置而非阻止提交。
+    # USER_PENDING_LIMIT 作为软上限（safe_enqueue 兜底），提高到 20 支持批量提交。
     try:
-        user_pending = generation_task_repository.count_pending_by_user(user_id)
         global_pending = generation_task_repository.count_pending_total()
-        if user_pending + count > USER_PENDING_LIMIT:
-            raise UserPendingLimitExceeded(
-                user_id=user_id, pending_count=user_pending + count, limit=USER_PENDING_LIMIT
-            )
         if global_pending + count > GLOBAL_PENDING_LIMIT:
             raise GlobalQueueFull(pending_count=global_pending + count, limit=GLOBAL_PENDING_LIMIT)
-    except UserPendingLimitExceeded as e:
-        raise HTTPException(
-            status_code=429,
-            detail=build_rate_limit_detail(e, generation_task_repository, scope="user"),
-        ) from e
     except GlobalQueueFull as e:
         raise HTTPException(
             status_code=503,
@@ -923,14 +1004,10 @@ def create_generation_task(
                 else:
                     failed_tasks.append(task)
             except UserPendingLimitExceeded as _e:
-                # 兜底：如果预检查后又并发提交了，在这里也拦住
-                failed_tasks.append(task)
-                if not created_tasks:
-                    raise HTTPException(
-                        status_code=429,
-                        detail=build_rate_limit_detail(_e, generation_task_repository, scope="user"),
-                    ) from _e
-                break
+                # Bug B #2098: 用户级限流已改为软限制，此分支理论上不再触发；
+                # 极端并发兜底仍入队（safe_enqueue 内部会打 warning 日志），不 429 拒绝
+                logger.warning("[生成任务] 用户 pending 超软限制，仍允许入队: task_id=%s", task.id)
+                created_tasks.append(task)
             except GlobalQueueFull as _e:
                 failed_tasks.append(task)
                 if not created_tasks:
@@ -1081,10 +1158,8 @@ def confirm_generation(
         ):
             logger.warning("[确认生成] 入队失败: task_id=%s", new_task.id)
     except UserPendingLimitExceeded as _e:
-        raise HTTPException(
-            status_code=429,
-            detail=build_rate_limit_detail(_e, generation_task_repository, scope="user"),
-        ) from None
+        # Bug B #2098: 用户级限流已软处理，理论上不再触发；作为防御仍放行
+        logger.warning("[任务] 用户 pending 超软限制，任务已入队")
     except GlobalQueueFull as _e:
         raise HTTPException(
             status_code=503,
@@ -1263,22 +1338,8 @@ def retry_generation_task(
         raise HTTPException(status_code=409, detail="Only failed tasks can be retried")
 
     user_id = authenticated_user.user.id
-    # 预检查：创建前判断，>= 上限就拒绝
-    user_pending = generation_task_repository.count_pending_by_user(user_id)
+    # 预检查（Bug B #2098）：只保留全局 503，用户级不再硬拒
     global_pending = generation_task_repository.count_pending_total()
-    if user_pending >= USER_PENDING_LIMIT:
-        raise HTTPException(
-            status_code=429,
-            detail=build_rate_limit_detail(
-                UserPendingLimitExceeded(
-                    user_id=user_id,
-                    pending_count=user_pending,
-                    limit=USER_PENDING_LIMIT,
-                ),
-                generation_task_repository,
-                scope="user",
-            ),
-        )
     if global_pending >= GLOBAL_PENDING_LIMIT:
         raise HTTPException(
             status_code=503,
@@ -1321,10 +1382,8 @@ def retry_generation_task(
         ):
             logger.warning("[生成任务] 重试入队失败: task_id=%s", retried.id)
     except UserPendingLimitExceeded as _e:
-        raise HTTPException(
-            status_code=429,
-            detail=build_rate_limit_detail(_e, generation_task_repository, scope="user"),
-        ) from None
+        # Bug B #2098: 用户级限流已软处理，理论上不再触发；作为防御仍放行
+        logger.warning("[任务] 用户 pending 超软限制，任务已入队")
     except GlobalQueueFull as _e:
         raise HTTPException(
             status_code=503,

apps/api/app/core/task_enqueue.py

@@ -6,7 +6,7 @@ from app.core.celery_app import celery_app
 logger = logging.getLogger(__name__)
 
 # ── 限流阈值常量（全系统统一管理，不要在业务代码里硬编码） ──
-USER_PENDING_LIMIT = 3  # 单用户 pending 上限
+USER_PENDING_LIMIT = 20  # 单用户 pending 上限（#2098: 从 3 提到 20，支持批量任务自动排队）
 GLOBAL_PENDING_LIMIT = 20  # 全局 pending 上限
 WORKER_CONCURRENCY = 4  # worker 渲染并发数（infra/docker/compose.yml WORKER_CONCURRENCY 默认值）
 
@@ -263,19 +263,18 @@ def safe_enqueue_generation_task(
         _mark_task_failed_safely(task, generation_task_repository, log_prefix, str(exc))
         raise exc
 
-    # 用户级限流检查（传了 user_id 才做）
+    # Bug B #2098: 用户级限流改为软提示，不再硬拒；所有任务都入队等待 worker 自然消费。
+    # user_pending_limit 作为兜底阈值保留（默认 20），达到时打 warning 日志但仍入队，
+    # 避免极端情况下恶意用户无限堆积任务。真正的系统保护由全局 GLOBAL_PENDING_LIMIT 承担。
     if user_id:
         user_pending = generation_task_repository.count_pending_by_user(user_id)
         if user_pending > user_pending_limit:
             logger.warning(
-                "[队列限流] 用户 pending 任务数超限(入队前): user_id=%s, count=%d/%d",
+                "[队列限流] 用户 pending 任务数超过软上限(入队): user_id=%s, count=%d/%d, 仍允许入队排队",
                 user_id,
                 user_pending,
                 user_pending_limit,
             )
-            exc = UserPendingLimitExceeded(user_id=user_id, pending_count=user_pending, limit=user_pending_limit)
-            _mark_task_failed_safely(task, generation_task_repository, log_prefix, str(exc))
-            raise exc
 
     # ── 发送 Celery 任务 ──
     try:
@@ -317,16 +316,18 @@ def safe_enqueue_generation_task(
     user_after = generation_task_repository.count_pending_by_user(user_id) if user_id else 0
 
     global_over = global_after > global_pending_limit
-    user_over = bool(user_id and user_after > user_pending_limit)
-
-    if global_over or user_over:
-        if global_over:
-            reason = f"全局 pending 超限(入队后): {global_after}/{global_pending_limit}"
-            exc = GlobalQueueFull(pending_count=global_after, limit=global_pending_limit)
-        else:
-            reason = f"用户 pending 超限(入队后): {user_after}/{user_pending_limit}"
-            exc = UserPendingLimitExceeded(user_id=user_id, pending_count=user_after, limit=user_pending_limit)
+    # Bug B #2098: 用户超限仅日志警告，不回滚任务
+    if user_id and user_after > user_pending_limit:
+        logger.warning(
+            "[队列限流] 用户 pending 超软上限(入队后): user_id=%s, count=%d/%d",
+            user_id,
+            user_after,
+            user_pending_limit,
+        )
 
+    if global_over:
+        reason = f"全局 pending 超限(入队后): {global_after}/{global_pending_limit}"
+        exc = GlobalQueueFull(pending_count=global_after, limit=global_pending_limit)
         logger.warning(
             "[队列限流] %s, task_id=%s, user_id=%s — 回滚状态为 failed",
             reason,

apps/worker/video_processing/render_adapter.py

@@ -132,6 +132,7 @@ class RenderAdapter:
         work_dir: Path | None = None,
         progress_cb: ProgressCallback | None = None,
         voiceover_audio_path: str | None = None,
+        task_config_override: dict | None = None,  # Bug A: task 级 config 覆盖，防并发竞态
     ) -> RenderAdapterResult:
         """渲染一个 EditPlan。
 
@@ -217,6 +218,7 @@ class RenderAdapter:
                 rendered_clip_ids=rendered_clip_ids,
                 failed_clip_ids=failed_clip_ids,
                 voiceover_audio_path=voiceover_audio_path,
+                task_config_override=task_config_override,
             )
             # 成功时将临时目录所有权转移给调用方，阻止 finally 清理
             if result.success and temp_dir:
@@ -392,7 +394,7 @@ class RenderAdapter:
 
         return asset_path_map, rendered_clip_ids, failed_clip_ids, asset_storage_map
 
-    def _prepare_bgm(self, plan, work_dir: Path, plan_id: str) -> str | None:
+    def _prepare_bgm(self, plan, work_dir: Path, plan_id: str, *, bgm_override: dict | None = None) -> str | None:
         """准备 BGM 音频文件（从 plan.config.bgm 读取配置）。
 
         支持 3 种来源（按优先级）：
@@ -405,7 +407,9 @@ class RenderAdapter:
         from urllib.parse import urlparse
 
         plan_config = plan.config or {}
-        bgm_config = plan_config.get("bgm", {}) or {}
+        bgm_config = dict(plan_config.get("bgm", {}) or {})
+        if isinstance(bgm_override, dict) and bgm_override:
+            bgm_config.update(bgm_override)  # Bug A: 任务级 BGM 覆盖，防并发竞态
 
         if not bgm_config.get("enabled", False):
             return None
@@ -567,6 +571,7 @@ class RenderAdapter:
         failed_clip_ids: list[str] | None = None,
         voiceover_audio_path: str | None = None,
         asset_storage_map: dict[str, str] | None = None,
+        task_config_override: dict | None = None,  # Bug A: task 级 config 覆盖，防并发竞态
     ) -> RenderAdapterResult:
         """执行统一渲染核心流程（BGM + ASR + 渲染 + 缩略图 + 上传）。
 
@@ -580,8 +585,9 @@ class RenderAdapter:
         Returns:
             RenderAdapterResult
         """
-        # 1. 准备 BGM
-        bgm_path = self._prepare_bgm(plan, work_dir, plan_id)
+        # 1. 准备 BGM（Bug A: 传 task 级 bgm override）
+        _bgm_override = (task_config_override or {}).get("bgm") if isinstance(task_config_override, dict) else None
+        bgm_path = self._prepare_bgm(plan, work_dir, plan_id, bgm_override=_bgm_override)
 
         self._report_progress(progress_cb, 40.0, "执行视频渲染")
 
@@ -589,8 +595,10 @@ class RenderAdapter:
         plan_config = plan.config or {}
         asr_service = self._get_asr_service()
 
-        # 3. 读取输出分辨率
-        export_config = plan_config.get("export", {}) or {}
+        # 3. 读取输出分辨率（Bug A: task override 优先）
+        export_config = dict(plan_config.get("export", {}) or {})
+        if isinstance(task_config_override, dict) and isinstance(task_config_override.get("export"), dict):
+            export_config.update(task_config_override["export"])
         if not isinstance(export_config, dict):
             export_config = {}
         output_width, output_height = _parse_resolution(export_config.get("resolution"))
@@ -615,6 +623,7 @@ class RenderAdapter:
             asr_service=asr_service,
             voiceover_audio_path=voiceover_audio_path,
             clip_has_text=clip_has_text,
+            override_config=task_config_override,
         )
         # 注入每个视频段对应素材的 storage_key，供全 GPU 直连管线直接签名下载
         _storage_map = asset_storage_map or {}

apps/worker/video_processing/unified_render_service.py

@@ -158,6 +158,7 @@ class UnifiedRenderService:
         bgm_path: str | None = None,  # BGM 本地文件路径
         voiceover_audio_path: str | None = None,  # 配音素材库音频本地路径
         clip_has_text: list[bool] | None = None,  # 源视频片段是否有文字（来自 atom_clip.ai_tags.has_text）
+        override_config: dict | None = None,  # Bug A: task 级 config 覆盖（title/bgm/export/subtitle），防并发竞态
     ):
         self.plan = plan
         self.clips = clips
@@ -170,6 +171,9 @@ class UnifiedRenderService:
         self.asr_service = asr_service
         self.bgm_path = bgm_path
         self.voiceover_audio_path = voiceover_audio_path
+        # Bug A: task 级 config override（深拷贝），优先级高于 plan.config；
+        # 避免同 plan 多任务并发渲染时 _sync_task_config_to_plan 写 plan.config["title"] 互相覆盖。
+        self._override_config = dict(override_config) if isinstance(override_config, dict) else {}
         # #1970：片段级文字检测（顺序与非 audio 的源视频片段一致）；None 表示无可靠检测，保守不翻转
         self._clip_has_text = clip_has_text
         self._transition_engine = TransitionEngine(default_duration=transition_duration)
@@ -180,6 +184,28 @@ class UnifiedRenderService:
         self._micro_plan_cache: Any = None
         self._micro_plan_loaded = False
 
+    def _cfg_section(self, section: str) -> dict:
+        """读取单个配置段：override_config 优先于 plan.config（Bug A 防并发竞态）。"""
+        base = dict((self.plan.config or {}).get(section, {}) or {})
+        override = self._override_config.get(section)
+        if isinstance(override, dict) and override:
+            base.update(override)  # 浅合并，保留 base 中未被覆盖字段
+        return base
+
+    def _effective_config(self) -> dict:
+        """读取完整 config：override_config 顶层段覆盖 plan.config（Bug A 防并发竞态）。"""
+        import copy
+
+        full = copy.deepcopy(self.plan.config or {})
+        for k, v in self._override_config.items():
+            if isinstance(v, dict):
+                sec = dict(full.get(k, {}) or {})
+                sec.update(v)
+                full[k] = sec
+            else:
+                full[k] = v
+        return full
+
     # ── #1970 PR2 智能降重：片段级微变换 ───────────────────────────────────
     def _dedup_enabled(self) -> bool:
         """读取 plan.config.dedup_enabled，缺省视为 True（向后兼容）。"""
@@ -431,7 +457,7 @@ class UnifiedRenderService:
             has_audio = pass_through_has_audio
             # 直通模式下也支持 BGM 混音：提取音频 → 混 BGM → 合并回视频
             if self.bgm_path and pass_through_has_audio:
-                config = self.plan.config or {}
+                config = self._effective_config()
                 bgm_config = config.get("bgm", {}) or {}
                 if bgm_config.get("enabled", False):
                     ctx = RenderContext(work_dir=self.work_dir, plan_id=self.plan.id)
@@ -471,7 +497,7 @@ class UnifiedRenderService:
                             "[unified-render] pass-through BGM mix failed, skipping: plan_id=%s", self.plan.id
                         )
         else:
-            config = self.plan.config or {}
+            config = self._effective_config()
             bgm_config = config.get("bgm", {}) or {}
             if not isinstance(bgm_config, dict):
                 bgm_config = {}
@@ -696,7 +722,7 @@ class UnifiedRenderService:
         Returns:
             ASS 文件路径，没有字幕时返回 None
         """
-        config = self.plan.config or {}
+        config = self._effective_config()
         # #1901 统一读 "title"，兼容老数据 "title_config"
         title_cfg = config.get("title", {}) or {}
         if not isinstance(title_cfg, dict) or not (title_cfg.get("text") or "").strip():
@@ -881,7 +907,7 @@ class UnifiedRenderService:
         Returns:
             是否成功添加了配音音轨
         """
-        config = self.plan.config or {}
+        config = self._effective_config()
         tts_cfg = config.get("tts", {}) or {}
         if not isinstance(tts_cfg, dict):
             tts_cfg = {}
@@ -2275,7 +2301,7 @@ class UnifiedRenderService:
         try:
             from video_processing import gpu_direct_pipeline as gdp
 
-            cfg = self.plan.config or {}
+            cfg = self._effective_config()
             video_layer = next(_lyr for _lyr in layers if _lyr.role not in ("audio",))
             video_clips = [c for c in video_layer.clips if c.clip_type != "audio"]
 

apps/worker/worker_app/tasks/generation.py

@@ -616,69 +616,49 @@ def _precompute_render_metadata(
 # ── Celery Task ──────────────────────────────────────────────────────────────
 
 
-def _sync_task_config_to_plan(source_edit_plan_id: str, task_info: dict, db) -> str | None:
-    """将 GenerationTask 的配置同步到 EditPlan.config，返回配音本地路径（如果有）。
+def _build_task_config_override(task_info: dict) -> dict:
+    """Bug A: 从 task_info 构建任务级 config override 深拷贝，供渲染时覆盖 plan.config。
 
-    包括：title_config、BGM、输出分辨率。配音单独处理（需下载到本地）。
+    所有渲染相关配置（title/bgm/export）从任务自身读取，不再依赖共享 plan.config，
+    彻底消除同 plan 多任务并发渲染时的竞态覆盖问题。
     """
-    from packages.adapters.sqlalchemy_impl.edit_plan_repository import (
-        SQLAlchemyEditPlanRepository,
-    )
+    import copy
 
-    plan_repo = SQLAlchemyEditPlanRepository(db)
-    plan = plan_repo.get(source_edit_plan_id)
-    if plan is None:
-        logger.error("[task] EditPlan not found: %s", source_edit_plan_id)
-        return None
+    override: dict = {}
 
-    plan_config = dict(plan.config or {})
-    changed = False
-
-    # 标题配置
+    # 标题配置（字段名归一化）
     title_config = task_info.get("title_config") or {}
-    if title_config and isinstance(title_config, dict) and title_config.get("text", "").strip():
-        cfg = dict(title_config)
-        # 字段名归一化
+    if isinstance(title_config, dict) and title_config:
+        cfg = copy.deepcopy(title_config)
         if "font_size" in cfg and "size" not in cfg:
             cfg["size"] = cfg["font_size"]
         if "font_color" in cfg and "color" not in cfg:
             cfg["color"] = cfg["font_color"]
-        plan_config["title"] = cfg
-        changed = True
-        logger.info("[task] title_config synced to plan: %s", cfg.get("text", "")[:30])
+        override["title"] = cfg
 
     # BGM 配置
     bgm_config = task_info.get("bgm_config") or {}
-    if bgm_config:
-        from packages.domain.bgm_utils import merge_bgm_config
-
-        existing_bgm = plan_config.get("bgm", {}) or {}
-        plan_config["bgm"] = merge_bgm_config(existing_bgm, bgm_config)
-        changed = True
+    if isinstance(bgm_config, dict) and bgm_config:
+        override["bgm"] = copy.deepcopy(bgm_config)
 
     # 输出分辨率
     ow = task_info.get("output_width") or OUTPUT_WIDTH
     oh = task_info.get("output_height") or OUTPUT_HEIGHT
     if ow >= 100 and oh >= 100:
-        export_cfg = dict(plan_config.get("export", {}) or {})
-        export_cfg["resolution"] = f"{ow}x{oh}"
-        plan_config["export"] = export_cfg
-        changed = True
+        override["export"] = {"resolution": f"{ow}x{oh}"}
 
-    if changed:
-        plan.config = plan_config
-        plan_repo.update(plan)
-        logger.info("[task] plan.config synced: plan_id=%s", source_edit_plan_id)
+    return override
+
+
+def _download_voice_for_task(task_info: dict, source_edit_plan_id: str) -> str | None:
+    """下载任务配音到本地临时文件，返回路径（不读写 plan.config）。"""
+    import tempfile
 
-    # 配音下载
     voiceover_path: str | None = None
     voice_library_id = task_info.get("voice_library_id", "")
-    # #1749：voice_ids 冗余字段已移除；配音一律以 voice_library_id 为准（独立配音每变体各自绑定）
     effective_voice_id = voice_library_id or ""
 
     if effective_voice_id:
-        import tempfile
-
         voice_tmp = Path(tempfile.gettempdir()) / f"voice_{source_edit_plan_id}_{id(task_info)}.mp3"
         try:
             if _download_voice_asset(effective_voice_id, voice_tmp):
@@ -697,6 +677,9 @@ def _render_from_edit_plan(
 ) -> tuple[Path, float, list[dict] | None, str | None, str | None, str, bool]:
     """从 EditPlan 数据库记录直接渲染（不再内存重建clips）。
 
+    Bug A 修复：不再通过 _sync_task_config_to_plan 写共享 plan.config；
+    渲染配置通过 task_config_override 参数直接传入渲染层，彻底消除并发竞态。
+
     Returns:
         (output_path, render_duration, cover_candidates, voiceover_path, temp_dir, thumbnail_url, edge_crop_applied)
     """
@@ -705,8 +688,10 @@ def _render_from_edit_plan(
 
     db = SessionLocal()
     try:
-        # 同步配置到 plan.config + 下载配音
-        voiceover_path = _sync_task_config_to_plan(source_edit_plan_id, task_info, db)
+        # Bug A: 构建任务级 config override（深拷贝自 task_info），不写 plan.config，避免并发竞态
+        task_override = _build_task_config_override(task_info)
+        # 下载配音到本地临时文件（不依赖 plan.config）
+        voiceover_path = _download_voice_for_task(task_info, source_edit_plan_id)
 
         # 进度回调
         def _progress_cb(progress: float, stage: str):
@@ -722,6 +707,7 @@ def _render_from_edit_plan(
             job_id=task_id,
             progress_cb=_progress_cb,
             voiceover_audio_path=voiceover_path,
+            task_config_override=task_override,
         )
 
         if not result.success: