Microsoft is introducing hidden APIs in VS Code, only accessible by their Copilot extension. These Proposed APIs are unstable and not yet publicly available. The community can test them in dev mode, but they cannot be published as live extensions.

This move has sparked concerns about anti-competition tactics, as some startups choose to fork VS Code to implement changes. Others argue that these new APIs could benefit open-source Copilot alternatives.

Source: https://old.reddit.com/r/ChatGPTCoding/comments/1g8xrub/microsoft_is_introducing_hidden_apis_to_vs_code/