Dexter for VS Code / Cursor

Dexter is a lightning fast, full-featured Elixir language server optimized for speed on large codebases.

Features

• Go-to-definition, find references, rename, and more!
• Autocompletion with snippet support across aliases, imports, and use injections
• Hover documentation for @doc, @moduledoc, @typedoc, and @spec
• Near-instant format on save, including support for any formatter plugins your project has configured, like Styler
• Syntax highlighting for Elixir, EEx, HEEx, and Livebook
• Monorepo-aware with automatic reindexing on git branch switches

See the Dexter repo for the full feature list.

Quick start

1. Install this extension from the VS Code or Cursor marketplace
2. Either set dexter.binary to the Dexter binary you want to use, or let the extension set Dexter up for you
3. Open any Elixir file — the index builds automatically on first startup

When dexter.binary is left at its default, the extension first looks for Dexter on your PATH. If it cannot find one, it downloads a checksum-verified binary into VS Code's extension storage. This does not modify your system installation. Extension-managed binaries can also be updated automatically.

If automatic installation is unavailable, follow Dexter's manual installation instructions. Native Windows support is best effort and automatic installation is unavailable. Configure a compatible Dexter executable with dexter.binary, or use the extension from a WSL workspace.

Dexter stores its project index in .dexter/. The directory manages its own .gitignore, so no project .gitignore entry is needed.

Configuration

Setting	Default	Description
dexter.binary	"dexter"	Path to the dexter binary, or a command name to find on PATH. Accepts ~ and workspace-relative paths
dexter.autoInstall	true	Download Dexter into extension storage when it is not installed
dexter.autoUpdate	true	Keep the extension-managed Dexter binary up to date
dexter.followDelegates	true	Follow defdelegate to the target function definition
dexter.maxTransientDocuments	50	Buffers the server keeps for files the editor never opened. 0 disables caching
dexter.stdlibPath	""	Path to the Elixir stdlib lib/ directory. Auto-detected if not set
dexter.debug	false	Enable verbose LSP logging (view with Output → Dexter)

Format on save

The extension does not change your format-on-save settings. To turn format on save on globally:

{
  "editor.formatOnSave": true
}

Or turn it on only for the languages Dexter supports:

{
  "[elixir][phoenix-heex]": { "editor.formatOnSave": true }
}

If another Elixir extension is installed, set Dexter as the default formatter. The extension ID is different in each editor:

// VS Code
{
  "[elixir]": { "editor.defaultFormatter": "remoteoss.dexter-lsp" }
}

// Cursor
{
  "[elixir]": { "editor.defaultFormatter": "remote-com-oss.dexter-lsp" }
}

Dexter settings are read when the language server starts. After you change one, the extension offers to restart the server. You can also restart it yourself from the Command Palette.

Commands

Command	Description
Dexter: Restart Language Server	Restarts the language server and applies the current settings. Use it after an update, or if the server stops responding

Development

git clone https://github.com/remoteoss/dexter-vscode.git
cd dexter-vscode
make install   # installs to Cursor by default, or: make install-vscode
make test      # runs the unit tests

The tests cover binary resolution, checksum verification, and the release asset mapping. They stub the vscode module, so they run under plain Node and need no editor. GitHub Actions runs them on every pull request.

Releasing

GitHub Actions builds and packages the extension, but the two marketplaces are published by hand. The marketplaces use different publisher namespaces, so each one needs its own package:

Editor	Marketplace	Extension ID
VS Code	Visual Studio Marketplace	remoteoss.dexter-lsp
Cursor	Open VSX	remote-com-oss.dexter-lsp

1. Create a release branch. Bump the version in package.json and add a CHANGELOG.md entry with a ## v<version> heading.
2. Merge the branch into main, then check out main.
3. Tag and push. The tag must match the version in package.json:

   make release VERSION=0.3.0

   The Release workflow then builds both packages and creates the GitHub release, using that version's CHANGELOG.md section as the release notes. It fails if the tag and package.json disagree, or if the changelog section is missing.
4. Publish to both marketplaces:

   export VSCE_PAT=...   # Visual Studio Marketplace token
   export OVSX_PAT=...   # Open VSX token
   make publish

   Or publish to one at a time with make publish-vscode and make publish-openvsx.

To build the packages without publishing, run make package and make package-openvsx. make package-openvsx sets the Open VSX publisher, builds the package, then restores package.json.