上线版: 产品表单统一+form嵌套修复+用户管理+部署+三套叙事

- 产品编辑入口统一走 ProductFormFull(卖点/风格/人群/品牌词全字段);
  修复开任务页 <form> 套 <form> 致"编辑产品"报错、改不了、跳回首个产品
- dashboard 入口卡片对齐实际路由: 系统管理(/config) 与 工作配置(/settings) 分开;
  settings ?tab=products 直达改用挂载后读 URL, 消除 hydration mismatch
- 新增用户管理(users API/admin service/改密页) + alembic 022/023/024
- 上线部署: Dockerfile / docker-compose.prod+https / nginx https / .env.example
- A8 三套正交叙事(痛点/场景/成分背书) + beige 调色去AI化 + 飞轮 text_import 高权重信号

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

backend/app/services/fission_service.py

@@ -23,6 +23,39 @@ logger = logging.getLogger(__name__)
 MAX_FANOUT = 5  # 每用户并发上限5(红线)；裂变 N 套直出受同等约束
 
 
+def _source_copy_from_payload(payload) -> str:
+    """从候选文案 JSON 中提取可裂变的正文，避免把整段 JSON 当 prompt。"""
+    if isinstance(payload, str):
+        raw = payload.strip()
+        if not raw:
+            return ""
+        try:
+            parsed = json.loads(raw)
+        except Exception:
+            return raw
+        return _source_copy_from_payload(parsed)
+
+    if isinstance(payload, dict):
+        parts: list[str] = []
+        for key in ("title", "content", "body", "note", "text", "opening", "selling_points", "tags"):
+            value = payload.get(key)
+            if isinstance(value, str) and value.strip():
+                parts.append(value.strip())
+            elif isinstance(value, list):
+                items = [str(item).strip() for item in value if str(item).strip()]
+                if items:
+                    parts.append(" / ".join(items))
+        if parts:
+            return "\n".join(parts)
+        return json.dumps(payload, ensure_ascii=False)
+
+    if isinstance(payload, list):
+        items = [_source_copy_from_payload(item) for item in payload]
+        return "\n".join(item for item in items if item)
+
+    return str(payload or "")
+
+
 def create_fission(
     db: Session, current_user: CurrentUser,
     source_task_id: int, reference_level: str, fanout_count: int,
@@ -73,5 +106,5 @@ def _extract_source_copy(db: Session, src: GenerationTask) -> str:
          .order_by(TextCandidate.is_selected.desc(), TextCandidate.id.asc())
          .first())
     if c and c.content:
-        return c.content
+        return _source_copy_from_payload(c.content)
     return src.theme or ""