Summary

• When a Grok 4.x model (e.g. x-ai/grok-4-fast, x-ai/grok-4.1-fast, x-ai/grok-4.20-beta) is routed to Vercel and reasoning is explicitly disabled, the Vercel model ID now uses the -non-reasoning suffix instead of -reasoning.
• mapModelIdToVercel accepts a new optional reasoningDisabled parameter (defaults to false); when true and the hardcoded Vercel ID ends with -reasoning, the suffix is replaced with -non-reasoning.
• Both call sites in vercel/index.ts (shouldRouteToVercel and applyVercelSettings) pass isReasoningExplicitlyDisabled(request) to keep routing checks and model name in sync.

Verification

• TypeScript environment not fully available locally (missing tsgo/jest binaries); relying on CI.

Visual Changes

N/A

Reviewer Notes

• The change is additive: non-Grok models and Grok models without reasoning disabled are unaffected.
• isReasoningExplicitlyDisabled already handles all three request kinds (chat_completions, messages, responses).