Using Proposed API
- Using a proposed API
- Proposed API incompatibility

Using Proposed API

At Visual Studio Code, we take Extension API compatibility seriously. We give our best effort to avoid breaking API changes, and extension authors could expect published extensions to continue to work. However, this puts great limitation on us: once we introduce an API, we cannot easily change it any more.

Proposed API solves the problem for us. Proposed API is a set of unstable API that are implemented in VS Code but not exposed to the public as stable API does. They are subject to change, only available in Insiders distribution and cannot be used in published extensions. Nevertheless, extension authors could test these new API in local development and provide feedback for VS Code team to iterate on the API. Eventually, Proposed API finds their way into the stable API and becomes available for all extensions.

Using a proposed API

These are the steps for testing Proposed API in local extension development:

Use Insiders release of VS Code.
Add "enableProposedApi": true to your package.json.
Copy the latest version of the vscode.proposed.d.ts into your project’s source location.

The vscode-dts CLI utility allows you to quickly download latest vscode.proposed.d.ts for extension development.

> npx vscode-dts dev
Downloading vscode.proposed.d.ts to /Users/username/Code/vscode-docs/vscode.proposed.d.ts
Please set "enableProposedApi": true in package.json.
Read more about proposed API at: https://code.visualstudio.com/api/advanced-topics/using-proposed-api

Here is a pre-configured sample using proposed API: proposed-api-sample.

Proposed API incompatibility

On the master branch, the vscode.proposed.d.ts is always compatible with vscode.d.ts. However, when you add vscode.proposed.d.ts to your project that uses @types/vscode, the latest vscode.proposed.d.ts might be incompatible with the version in @types/vscode.

You can solve this issue by either:

Remove dependency on @types/vscode and use npx vscode-dts master to download vscode.d.ts from microsoft/vscode master branch.
Use @types/vscode@<version> and also use npx vscode-dts dev <version> to download the vscode.proposed.d.ts from an old branch of microsoft/vscode. However, be careful the API might have changed in the latest version of VS Code Insiders.