chore(langchain): qwen support in _init_chat_model_helper

[keenborder786]

• Fixes Add support for ChatQwen in init_chat_model() #34183
• Simple Addition of langchain_qwen in init_chat_model
• Related PR in Docs: chore: Qwen Support in Providers docs#1732

[TBice123123]

1. There is no langchain-qwen. You probably mean langchain-qwq.
2. langchain-qwq is better suited for use with ChatQwen, as it supports more models, whereas QWQ only supports the QWQ model.
3. langchain-qwq is a third-party library with low update frequency, so it's not really suitable to be included in init_chat_model. The integrations in init_chat_model are generally officially maintained, and langchain-qwq is not one of them.

[keenborder786]

Please see: https://docs.langchain.com/oss/python/integrations/chat/qwen

[TBice123123]

I wrote this content myself—how could I not know it? Look closely; isn't it langchain-qwq?

[TBice123123]

First of all, I greatly appreciate your support for ChatQwen. I made the majority of the contributions to ChatQwen, while the original author @yigit353 primarily contributed to ChatQwQ. However, I believe that since ChatQwen was developed by a third party and is not officially maintained, it shouldn't be included in init_chat_model. Moreover, it lacks a JavaScript version, which would lead to inconsistencies between the two language implementations if it were included—a situation I think the official team would discourage.

[keenborder786]

@TBice123123 okay, so what do you suggest, should we ask Langchain Team to officially support this package then?

[keenborder786]

@ccurme any suggestions?

[keenborder786]

@mdrxy any suggestion from you?

[ccurme]

LangChain maintainers don't maintain or have access to langchain-qwen, so I'd prefer not to add it here for now.

Let me know if this is blocking any usage, you should be able to run

from langchain_qwen import ChatQwQ

model = ChatQwQ(model=model, **kwargs)

and use this in create_agent or other places.