fix: add xAI models grok-4.20-multi-agent-0309

[github-actions]

fix: add xAI models grok-4.20-multi-agent-0309

Closes #666

Source issue: #666

Summary

Field	Value
Provider	xai
Primary model	grok-4.20-multi-agent-0309
Changed models	grok-4.20-multi-agent-0309
Added models	grok-4.20-multi-agent-0309
Updated models	None
Verification sources	1 2

Verified metadata

Model	Display name	Parent	Providers	Format	Flavor	Token limits	Pricing	Lifecycle
grok-4.20-multi-agent-0309			xAI	openai	chat	input=1000000, output=not provided	in/out=1.25/2.5 per 1M; cache read=0.2 per 1M	multimodal=true; reasoning=true

Verification notes

No LLM verification step ran — model metadata was already complete in the issue.

sync_models vs proposed update

sync_models cross-check found differences. Official provider verification was used for the applied values, and sync_models discrepancies are listed below for review.

Model	Field	Proposed update	sync_models	sync_models source models
grok-4.20-multi-agent-0309	catalog entry	present	missing	None

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Project	Deployment	Actions	Updated (UTC)
ai-proxy	Ready	Preview, Comment	May 28, 2026 11:18am

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[chatgpt-codex-connector]

Route multi-agent through Responses API

For this model, flavor: "chat" makes the proxy's /auto path select /chat/completions (see packages/proxy/src/proxy.ts switch on modelSpec.flavor), and normal chat-completion calls are forwarded to xAI's /chat/completions. xAI's current multi-agent docs state that grok-4.20-multi-agent does not work with the OpenAI Chat Completions API and must use the xAI SDK or Responses API instead, so users who pick the newly added model through the standard chat route will get provider errors rather than a working model.

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