xslint-lsp

A Language Server Protocol server that surfaces xslint's diagnostics as you type — squiggles in your editor instead of a failed build.

xslint lints XSL/XSLT stylesheets — malformed XML, invalid XPath, and stylistic defects — but only in the terminal and CI. This wraps xslint's engine in an LSP server, so the same defects light up in any LSP-capable editor: VS Code, Neovim, and JetBrains IDEs (via LSP4IJ or their built-in LSP support).

Because it is a thin transport over xslint — it calls xslint's lint(sources) in-process and maps each defect onto an LSP Diagnostic — there is no second rule engine to keep in sync.

How it works

editor  ──(LSP over stdio)──▶  src/server.js
                                  │  lint(buffer)      → @xslint/xslint
                                  │  diagnostics(defects)  → src/diagnostics.js
                                  ▼
editor  ◀──(publishDiagnostics)──  { range, severity, code: rule, message }

The server keeps open documents in sync, re-lints on every change (checking the live buffer, not the saved file), and clears a file's diagnostics when it closes. Each xslint defect {name, severity, message, line, pos} becomes an LSP diagnostic whose code is the rule name and whose source is xslint.

It also offers code actions: a quick-fix on each fixable defect and a fix all action for the safe fixes. Both are computed by xslint's own fixed engine, so an editor fix is byte-for-byte identical to a command-line --fix.

Run it

The server speaks LSP over stdio:

npm install
node src/server.js --stdio

Point any LSP client at that command for .xsl/.xslt files.

Editor extension

A VS Code-compatible extension lives in client/; it bundles and launches this server. It's published to Open VSX and attached as a .vsix to every release — it is not on the Microsoft VS Code Marketplace.

• Cursor, VSCodium, Windsurf, Gitpod — search xslint in the Extensions view (they install from Open VSX).
• VS Code — code --install-extension xslint-vscode-<version>.vsix, or Extensions → ⋯ → Install from VSIX… with the release's .vsix.

See client/README.md for the full guide. To hack on the extension, open this repo and press F5; to build a .vsix, run cd client && npm run package. Releases publish it automatically (see RELEASING.md).

Development

npm test        # unit tests + an end-to-end LSP round-trip
npm run coverage   # the same, under c8 with a 100% gate
npm run lint    # eslint (google + @stylistic)

Tests run on Node's built-in runner (node --test). test/diagnostics.test.js covers the defect→diagnostic mapping; test/server.test.js spawns the server and drives it through open/change/close, asserting the diagnostics it publishes — and it exits the server cleanly so its subprocess coverage is captured.

License

MIT — see LICENSE.txt.