GitHub Copilot to retire six AI models on December 14

GitHub will deprecate six models across all Copilot experiences on December 14, 2026. The change covers Copilot Chat, inline edits, ask and agent modes, and code completions. The affected models are Claude Fable 5, Claude Haiku 4.5, Gemini 3.8 Flash, Gemini 4 Argon, Grok 4.6, and Kimi K3.

GitHub suggests a replacement for each model. Claude Fable 5 maps to Claude Fable 5.2, Claude Haiku 4.5 to Claude Haiku 5.5, Gemini 3.8 Flash to Gemini 4 Hydrogen, Gemini 4 Argon to Gemini 4 Carbon, and Grok 4.6 to Grok 4.7. The suggested alternative for Kimi K3 has not been announced.

Claude Haiku 4.5 will remain available to individual Copilot subscribers on annual plans.

Why it matters

Teams that have pinned a specific model in prompts, workflows, or integrations will need to update those settings before the cutoff. Results from a replacement model may differ in style, speed, or accuracy, so outputs should be checked after the switch. Organizations that depend on a particular model for consistent output should test the alternatives in advance.

What to do

Update workflows and integrations to use supported models before December 14. Copilot Enterprise and Business admins should confirm that suggested alternatives are enabled under default model enablement, or enable them through model policies in Copilot settings if the global default has been turned off. Enterprise customers with concerns can contact their GitHub account team, and readers should confirm the Kimi K3 replacement on GitHub’s documentation for supported models.