存量积累：生图素人感约束+评图分+幂等防重跑+审核回路

- 015-017迁移：image_candidate 文案复审/AI视觉分/重生标记
- constants C7素人感约束(反电商摆拍对齐真实笔记)+C3叠字口子
- celery visibility_timeout=2h 防长任务被误判重投重复烧钱(task75教训)
- image_scorer 评图分(只筛选+展示,真实信号才进飞轮权重)
- storyboard/image_gen/pipeline_io 生图存量
- task_actions/tasks/task_service/flywheel 审核回路+飞轮存量

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/api/v1/task_actions.py

@@ -95,22 +95,38 @@ def import_text(
     return ok(_fmt_text(tc))
 
 
+class RegenerateRequest(BaseModel):
+    """R2 重生参数（全 None=整体重生，兼容旧调用）。
+    strategy='A'/'B'/'C' 指定单套；role 指定单张(需配 strategy)；custom_prompt 人工追加提示词。"""
+    strategy: str | None = Field(default=None, pattern="^[ABC]$")
+    role: str | None = None
+    custom_prompt: str | None = Field(default=None, max_length=500)
+
+
 @router.post("/{task_id}/regenerate")
 def regenerate(
     task_id: int,
+    body: RegenerateRequest | None = None,
     current_user: Annotated[CurrentUser, Depends(require_write_permission)] = None,
     db: Session = Depends(get_db),
 ):
-    """重新生成（飞轮信号 regenerate -1）。"""
+    """重新生成（飞轮信号 regenerate -1）。
+    body 全空=整体重生；带 strategy=单套重生；带 strategy+role=单张重生；custom_prompt=人工提示词。"""
     from app.services.flywheel_service import record_signal
     from app.services.task_service import enqueue_generation
     task = _check_task_ownership(
         db.query(GenerationTask).filter(GenerationTask.id == task_id).first(),
         current_user.workspace_id,
     )
+    body = body or RegenerateRequest()
+    # role 必须配 strategy（单张重生需知道是哪套的哪张）
+    if body.role and not body.strategy:
+        raise_state_invalid("指定单张重生(role)时必须同时指定 strategy(套别)")
     record_signal(db, current_user, task, "regenerate")
-    enqueue_generation(task.id)
-    return ok({"task_id": task_id, "status": "regenerating"})
+    enqueue_generation(task.id, regen_strategy=body.strategy,
+                       regen_role=body.role, custom_prompt=body.custom_prompt)
+    scope = "单张" if body.role else ("单套" if body.strategy else "整体")
+    return ok({"task_id": task_id, "status": "regenerating", "scope": scope})
 
 
 @router.post("/{task_id}/submit-review")