The option just shown up in Copilot settings page for me
GitHub says "Claude Opus 4 is hosted by Anthropic PBC. Claude Sonnet 4 is hosted by Anthropic 1P."[1]. What's Anthropic 1P? Based on the only Kagi result being a deployment tutorial[2] and the fact that GitHub negotiated a "zero retention agreement" with the PBC but not whatever "1P" is, I'm assuming it's a spinoff cloud company that only serves Claude...? No mention on the Wikipedia or any business docs I could find, either.
Anyway, off to see if I can access it from inside SublimeText via LSP!
[1] https://docs.github.com/en/copilot/using-github-copilot/ai-m...
[2] https://github.com/anthropics/prompt-eng-interactive-tutoria...
So far I have found it pretty powerful, its also the first time an LLM has ever stopped while working to ask me a question or for clarification.
"Claude Opus 4 and Claude Sonnet 4 are hosted by Anthropic PBC and Google Cloud Platform."
They also mention:
"GitHub has provider agreements in place to ensure data is not used for training."
They go on to elaborate. Perhaps this kind of offering instills confidence in some who might not trust model providers 1:1, but believe they will respect their contract with a large customer like Microsoft (GitHub).