Support for xAI SuperGrok/SuperGrok Heavy OAuth with BYOK.

[ScionOfDesign]

GitHub Copilot is one of the best harnesses on the market and, with the launch of Grok Build, xAI has been open about their support for 3rd-party harnesses such as OpenCode, OpenClaw, and Hermes Agent (While Anthropic has been openly hostile to third-party harnesses).

Currently, using my temporary xAI OAuth token instead of API Key actually works with GitHub Copilot right now.
The only issue is that they key needs to be updated every time it expires.

Official support for OAuth instead of just permanent Api Keys for endpoints that support it would be greatly appreciated.

[ScionOfDesign]

I was able to create a proof-of-concept for this functionality of authenticating with xAI OAuth here, based on how OpenCode and Hermes Agent do it:
https://github.com/ScionOfDesign/vscode/tree/feature/xai-oauth

A lot of work would still need to be done in order to allow people to actually manage the authentication via the Provider UI, but this proves that this functionality is doable.

[ScionOfDesign]

It seems that they changed their permitted redirect uri's to only include loopback addresses.
I have added a temporary loopback server which still allows for authentication, but this is not ideal.
It is also affecting OpenClaw: openclaw/openclaw#83425