vercel/ai with Expo

[younes200]

Hi
I'm try to use vercel/ai with @expo the issue is @expo use @remix-run/node as part of the server api runtime which rely on @remix-run/web-stream and cause ReadableStream incompatibility :

ai/packages/provider-utils/src/response-handler.ts

Line 98 in 4d458df

value: response.body

The error being raised is:

TypeError: First parameter has member 'readable' that is not a ReadableStream.
    at assertReadableStream (/Users/x/test-ai/node_modules/web-streams-polyfill/src/lib/validators/readable-stream.ts:5:11)
    at convertReadableWritablePair (/Users/x/test-ai/node_modules/web-streams-polyfill/src/lib/validators/readable-writable-pair.ts:15:3)
    at ReadableStream.pipeThrough (/Users/x//test-ai/node_modules/web-streams-polyfill/src/lib/readable-stream.ts:223:23)

Is there a way for solve the issue ?

[lgrammel]

Not sure if this helps, but the AI SDK uses the Node standard fetch.

Have you tried setting the following in vite.config.js?

installGlobals({ nativeFetch: true })

More info: https://remix.run/docs/en/main/guides/single-fetch

[younes200]

rhank you, @lgrammel. It's certainly due to the configuration of Remix.

[ekimcem]

Were you able to use ai sdk in Expo ?

I think you have a seperate nodejs as backend, am i wrong ?

[younes200]

no, I'm using Expo Router API which running on remix-node I believe. Also React Native doesn't support fetch streams for now : facebook/react-native#27741

[ekimcem]

That's really bad, nowadays everyone needs streams... I think using event source is another approach, lets see if they will work on an ai sdk, thanks for answer btw.

[lgrammel]

Not sure if it helps, but you can set a custom fetch function on most providers now, e.g. for the OpenAI provider: https://sdk.vercel.ai/providers/ai-sdk-providers/openai#provider-instance

[ekimcem]

The important thing is not really what the Vercel SDK provides, but rather that the React Native and Expo teams need to address fetch streams. I hope they work on this issue. Still, thank you very much!