feat: 重构资料包模型与会话绑定主链路

apps/chat/services.py

@@ -0,0 +1,26 @@
+from .models import Conversation
+
+
+def create_conversation_for_batch(batch_id: str, product_name: str) -> Conversation:
+    """
+    为资料包创建主会话。
+
+    会话标题固定优先使用解析出的产品名称，
+    缺失时回退到批次号，确保前台始终有稳定标题。
+    """
+    conversation = Conversation.objects.create(
+        conversation_id=_generate_conversation_id(),
+        title=product_name or f"未命名资料包-{batch_id}",
+        product_name=product_name,
+        batch_id=batch_id,
+        task_status=Conversation.STATUS_PENDING,
+        node_results=[
+            {"code": "package_import", "label": "资料包导入", "status": "已完成"},
+            {"code": "overview", "label": "目录汇总", "status": "处理中"},
+        ],
+    )
+    return conversation
+
+
+def _generate_conversation_id() -> str:
+    return f"conv-{Conversation.objects.count() + 1:03d}"