Release Notes:

- Added support for Grok 4.1 Fast (reasoning and non-reasoning) models
in the xAI provider, with 2M token context windows and full vision
capabilities.
- Extended 2M token context to existing Grok 4 Fast variants (from 128K)
for consistency with xAI updates.
- Enabled image/vision support for all Grok 4 family models.

Doc:
https://docs.x.ai/docs/models/grok-4-1-fast-reasoning
https://docs.x.ai/docs/models/grok-4-1-fast-non-reasoning