fix: cloudflare-ai-gateway sdk.chat undefined error

[englishm]

Summary

Fixes the sdk.chat is not a function error when using Cloudflare AI Gateway as a provider.

• Changed sdk.chat(modelID) to sdk.languageModel(modelID) in the cloudflare-ai-gateway custom loader

Problem

The @ai-sdk/openai-compatible SDK (which Cloudflare AI Gateway uses per models.dev) does not have a .chat() method. It only exposes .languageModel() and .chatModel(). This caused the error:

ERROR sdk.chat is not a function. (In 'sdk.chat(modelID)', 'sdk.chat' is undefined)

The original PR #5174 was merged with sdk.chat(), even though the author noted in a comment that they had "fixed the way we call the openai-compatible SDK (.languageModel)" - that fix was never actually committed.

Solution

Use .languageModel() which is the standard method available on all AI SDK providers and matches how other providers in this file work (see bedrock, google-vertex, sap-ai-core, etc.).

Testing

Tested locally with Cloudflare AI Gateway credentials - models now load and respond correctly.

---

This fix was developed entirely using opencode itself 🎉

Fixes #6262