Ruddy for VS Code

Syntax highlighting for .rud files using the bundled Ruddy Tree-sitter parser, plus diagnostics, hover, completion, go-to-definition, and document formatting through ruddy lsp.

Install

From a Ruddy checkout, just vscode-install regenerates and checks the grammar, builds the extension, and installs it with code --install-extension --force. The code command must be on PATH. An alternative executable can be selected with just vscode-install code-insiders. Use just vscode to build the VSIX without installing it; this writes editors/vscode/ruddy.vsix.

In VS Code, run Extensions: Install from VSIX… and select the downloaded or locally built .vsix file. Highlighting works immediately, including standalone files and Restricted Mode. It uses VS Code semantic tokens, enabled by default for Ruddy. If you override editor.semanticHighlighting.enabled to false, highlighting is disabled; there is no TextMate fallback.

For language server features, install the Ruddy CLI. From a checkout of Ruddy, with Rust and just installed:

just install

Make sure ruddy is on the PATH visible to VS Code, or set Ruddy › Server: Path (ruddy.server.path) to the executable. Enter a path, not a shell command; the extension supplies the lsp argument. Relative paths resolve from the project workspace folder. Restart VS Code after changing your shell's PATH.

Open the folder containing Ruddy.toml, then open a .rud file and trust the workspace to start the language server. A multi-root workspace gets one server per folder with a Ruddy.toml directly at its root. Add nested projects as workspace folders explicitly; the extension does not search for them. Files outside those project folders have highlighting only.

Use Format Document for formatting. Format-on-save follows your own VS Code settings. Use Ruddy: Restart Language Server to recover a stopped server; details appear in the Ruddy output channel. Changing the executable setting automatically restarts affected servers.

Desktop VS Code and remote workspaces are supported. For SSH, WSL, or containers, install the extension and Ruddy on the remote host; the executable setting and PATH are resolved there. Browser-only VS Code is not supported.

Develop and package

Requires Node.js 20 or newer and npm. From editors/vscode:

npm ci
npm run build
npm run typecheck
npm run test:unit
npm run package

The build compiles treesitter/src/parser.c to WASM, copies the existing treesitter/queries/highlights.scm and Tree-sitter runtime, and bundles the extension's JavaScript and dependency licenses. Tree-sitter's build tool fetches wasi-sdk on its first build. End users need none of these build dependencies. After grammar changes, run just grammar at the repository root before rebuilding the extension. Generated extension assets and VSIX packages are not committed.

For the full extension tests, first run cargo build -p ruddy --bin ruddy at the repository root, then npm test here. On headless Linux, use xvfb-run -a npm test. The tests download VS Code 1.96.4, the minimum supported release, and exercise the extension in an isolated profile with temporary projects and the real server. Set RUDDY_TEST_BINARY to use another compiler binary, or VSCODE_TEST_VERSION to test another editor release. Rust tests must run through just test.

The highlighter keeps a parser and syntax tree per requested document. Each edit updates tree coordinates before the next incremental parse, including multicursor edits and UTF-16 positions. Highlight queries currently run over the resulting whole tree; incremental parsing does not imply incremental query evaluation.