How to set additional http headers when creating a model

OSS Product Help LangChain
1

Using LangChain with Typescript and working with google-genai, I want to use initChatModel so that I can have support for other model providers. My GOOGLE_API_KEY requires a specific referer http header to be set. I have not been able to find documentation or solutions through AI on how to properly do this.

With google’s genai library I do this to set it when creating the client:

new GoogleGenAI({
      apiKey,
      httpOptions: { headers: { referer }, timeout: 600000 },
    });

I’ve tried a lot of different combinations with LangChain using initChatModel but nothing seems to work. Here is my latest attempt:

await initChatModel(modelName, {
          thinkingConfig: { thinkingBudget: this.thinkingBudget },
          clientOptions: {
            httpOptions: {
              headers: { referer: this.referer },
            },
          },
        })

Does anyone know if there is a way to do this?