This is the place for the stable API and for API proposals.

1. find a proposal you are interested in
2. add its name to your extensions package.json#enabledApiProposals property
3. run npx vscode-dts dev to download the d.ts files into your project
4. don't forget that extension using proposed API cannot be published
5. learn more here: https://code.visualstudio.com/api/advanced-topics/using-proposed-api

1. create a new file in this directory, its name must follow this pattern vscode.proposed.[a-zA-Z]+.d.ts
2. creating the proposal-file will automatically update src/vs/platform/extensions/common/extensionsApiProposals.ts (make sure to run npm run watch)
3. declare and implement your proposal
4. make sure to use the checkProposedApiEnabled and/or isProposedApiEnabled-utils to enforce the API being proposed. Make sure to invoke them with your proposal's name which got generated into extensionsApiProposals.ts
5. Most likely will need to add your proposed api to vscode-api-tests as well