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Welcome! So glad you've decided to help make Cursorless better. You'll want to start by getting set up and learning how to run / test a local copy of the extension. You may also find the VSCode API docs helpful to learn about VSCode extension development.

Initial setup


  • Git
  • Node.js
  • Corepack or pnpm
  • VSCode; minimum version for local development is 1.72.0 in order to support settings profiles for sandboxed development. Please file an issue if that is a problem.


  1. Clone cursorless

  2. Open the newly created cursorless directory in VSCode. If you're on Windows, don't use WSL (see #919 for discussion / workaround).

  3. Run the following in the terminal:

    pnpm install
    pnpm compile
  4. Run

    code --profile=cursorlessDevelopment

    and then close the window that opens (eg say "window close"). This step is necessary to create the VSCode settings profile that acts as a sandbox containing a specific set of VSCode extensions that will be run alongside Cursorless when you launch Cursorless in debug or test mode. Once is resolved, we will be able to remove this step, as the profile can then automatically be created.

  5. Run the following in the terminal:

    pnpm init-vscode-sandbox

    The pnpm init-vscode-sandbox command creates a local VSCode settings profile that acts as a sandbox containing a specific set of VSCode extensions that will be run alongside Cursorless when you launch Cursorless in debug or test mode. This approach is suggested by the VSCode documentation. If you need to update any of the extension dependencies in the sandbox, you can add --force to the command. If you'd like to use additional extensions when debugging locally, you can use the following command:

    code --profile=cursorlessDevelopment --install-extension some.extension

    where some.extension is the id of the extension you'd like to install into the sandbox.

    Note that if you are adding support for a new language that isn't in the default list of language identifiers supported by VSCode, you may need to add an extension dependency. See Adding a new language for more details.

  6. Copy / symlink cursorless-talon-dev into your Talon user directory for some useful voice commands for developing Cursorless.

Running / testing extension locally

In order to test out your local version of the extension or to run unit tests locally, you need to run the extension in debug mode. To do so you need to run the workbench.action.debug.selectandstart command in VSCode and then select either "Run Extension" or "Extension Tests".

Running a subset of tests

The entire test suite takes a little while to run (1-2 mins), so you may want to run just a subset of the tests.

To specify the set of tests to run, say "debug generate subset", or if you haven't installed the cursorless-talon-dev files, run the VSCode task "Generate test subset file". To do this, choose "Tasks: Run Task" from the command pallete.

To run the specified subset of tests, use the "Run test subset" launch config instead of the usual "Extension Tests".

If you need to edit the subset of tests to run in the future, you can say "debug edit subset".

Code formatting

We use pre-commit to automate autoformatting. Autoformatters will automatically run on PRs in CI, but you can also run them locally or install pre-commit hooks as described in the pre-commit documentation.

Running docs site locally

Run the workbench.action.debug.selectandstart command and then select "Docusaurus Start (Debug)".

Adding tests


It is also possible to write manual tests. When doing so, we have a convention that any test that must be run within a VSCode context (eg because it imports "vscode"), should be placed in a file with the suffix .vscode.test.ts. All other tests should end with just .test.ts. This allows us to run non-VSCode tests locally outside of VSCode using the Run unit tests launch config. These tests run much faster than the full VSCode test suite.

Parse tree support

Adding a new programming language

See docs.

Adding syntactic scope types to an existing language


Testing Cursorless with a local version of the VSCode parse tree extension

First bundle the parse tree extension into a .vsix, using something like the following:

cd ../vscode-parse-tree
vsce package -o bundle.vsix

Once you have your package then you can install it into the sandbox using the following command:

code --profile=cursorlessDevelopment --install-extension bundle.vsix

Installing a local build of the Cursorless extension

You can install a local build of the Cursorless extension by running the following command:

pnpm -F cursorless-vscode install-local

This will bundle and install a local version of Cursorless, uninstalling production Cursorless first and using a special extension id to break the update chain.

If you don't want to have to check out the PR and do the build yourself, you can use install-from-pr instead, and pass a PR number to the command and it will download and install the artifact from the PR build. This requires the gh cli. For example:

pnpm -F cursorless-vscode install-from-pr 1281

To uninstall the local build and revert to production cursorless, run the following command:

pnpm -F cursorless-vscode uninstall-local

Changing SVGs

SVG preprocessing script

You'll probably want to run the following to make sure the SVGs have everything they need:

pnpm -F @cursorless/cursorless-vscode preprocess-svg-hats

This script will add dummy width, height and fill attributes as necessary to appease the regex in Decorations.ts

Adding hat adjustments at finish

While tweaking, the easiest approach is probably to use the cursorless.individualHatAdjustments setting in your settings.json to change size / alignment so you don't need to refresh every time. Once you're done, you can paste the settings into packages/cursorless-vscode/src/scripts/hatAdjustments/add.ts and run the following to get your updates:

pnpm -F @cursorless/cursorless-vscode hat-adjustments-add

If instead, you want to average your adjustments with those in main and see the differences to get to yours and main, you can paste the settings into packages/cursorless-vscode/src/scripts/hatAdjustments/average.ts and run:

pnpm -F @cursorless/cursorless-vscode hat-adjustments-average