Add functionality to send extra body arguments within streamText API

[RostyslavManko]

The Vanilla Vercel AI SDK doesn't support sending extra body arguments like provider, route, and others, which OpenRouter provides. These arguments are essential for fully using the OpenRouter. Please add support for these arguments to the streamText function.

[daun-io]

Hi @RostyslavManko,

Thanks for the request. We've created an extraBody argument.

You can use it like this:

import { createOpenRouter } from "@ai-sdk/openrouter";

const provider = createOpenRouter({
  apiKey: "your-api-key",
  // Extra body to pass to OpenRouter
  extraBody: {
    custom_field: "custom_value",
    providers: {
      anthropic: {
        custom_field: "custom_value",
      },
    },
  },
});
const model = provider.chat("anthropic/claude-3.5-sonnet");
const response = await model.doStream({
  inputFormat: "prompt",
  mode: { type: "regular" },
  prompt: [{ role: "user", content: "Hello" }],
});

[RostyslavManko]

Could you please update @openrouter/ai-sdk-provider's package so we can start using it? The last update was a month ago.