# xai/grok-4.1-fast-reasoning

Vertex AI deprecated the model xai/grok-4.1-fast-reasoning without giving a shutdown date yet.

- API: Vertex AI (aiplatform.googleapis.com)
- Model: xai/grok-4.1-fast-reasoning
- Released: November 19, 2025 (models.dev)
- Kind: Model retirement
- Takes effect: no date given yet
- Calls after that day: fail
- Calls it hits: `model xai/grok-4.1-fast-reasoning`
- Source: [models.dev](https://models.dev/api.json#google-vertex)
- Verified: November 6, 2026, against Vertex AI's own pages
- Page: https://www.okapi.bot/models/vertex-ai/xai/grok-4.1-fast-reasoning/

Okapi finds the calls this change hits in your repo and opens the pull request with the fix: https://github.com/apps/okapi-agent