configurable data is no longer included in the metadata.

### Submission checklist - [x] This is a bug, not a usage question. - [ ] I added a clear and descriptive title that summarizes this issue. - [ ] I used the GitHub search to find a similar question and didn't find it. - [ ] I am sure that this is a bug in LangChain rather than my code. - [ ] The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package). - [ ] This is not related to the langchain-community package. - [ ] I posted a self-contained, minimal, reproducible example. A maintainer can copy it and run it AS IS. ### Package (Required) - [ ] langchain - [ ] langchain-openai - [ ] langchain-anthropic - [ ] langchain-classic - [x] langchain-core - [ ] langchain-model-profiles - [ ] langchain-tests - [ ] langchain-text-splitters - [ ] langchain-chroma - [ ] langchain-deepseek - [ ] langchain-exa - [ ] langchain-fireworks - [ ] langchain-groq - [ ] langchain-huggingface - [ ] langchain-mistralai - [ ] langchain-nomic - [ ] langchain-ollama - [ ] langchain-openrouter - [ ] langchain-perplexity - [ ] langchain-qdrant - [ ] langchain-xai - [ ] Other / not sure / general ### Related Issues / PRs <img width="1358" height="290" alt="Image" src="https://github.com/user-attachments/assets/5f83258a-f6a8-4fb6-9806-9eb77ac0ae40" /> Since `langchain-core 1.3.0`, `configurable` section is no longer stored in the `metadata` due to commit af4d711a2f2ebcaa524af34abb0262dfdac9678a ### Reproduction Steps / Example Code (Python) ```python session_store = {} def get_session_history(session_id): if session_id not in session_store: session_store[session_id] = ChatMessageHistory() return session_store[session_id] def demo_langchain_history_stream(): session_id = "demo_session_123123" prompt = ChatPromptTemplate.from_messages([ ("system", "你是一个乐于助人的助手"), ("human", "{input}"), ]) chain = prompt | llm | StrOutputParser() agent = RunnableWithMessageHistory(chain, get_session_history, …