Editor setup

You want diagnostics, completion, hover, and navigation while you edit .sysml and .kerml files in VS Code. That comes from two pieces: the sysml-lsp-server language server (a Rust binary) and a thin client extension that launches it. This page covers the VS Code setup; for the server as an interface in its own right — its capabilities, generic LSP clients like Helix or Neovim, and the WebSocket bridge — see the language server.

Before you start

The extension is not published to the VS Code Marketplace or Open VSX. Install it from the .vsix attached to the latest release — one per platform, each with the language server bundled — or build it from a source checkout.

# Linux x86-64; substitute your platform's asset name
curl -L -O https://github.com/RickyMillar/sysml-rs/releases/latest/download/sysml-linux-x64-0.1.0.vsix
code --install-extension sysml-linux-x64-0.1.0.vsix

The published packages are sysml-{linux-x64,linux-arm64,darwin-arm64,darwin-x64,win32-x64}-0.1.0.vsix. They carry the extension’s own version (0.1.0), which is not the release tag — check the release you downloaded from rather than the filename.

To build both from source instead, follow the installation guide first so that cargo builds work in your clone.

VS Code

1. Build the language server

cargo build --release -p sysml-lsp-server

The binary lands at target/release/sysml-lsp-server.

2. Package and install the extension

The extension lives in editors/vscode. Packaging it produces a .vsix you install into your normal VS Code:

cd editors/vscode
npm ci
npm run package        # runs vsce; produces sysml-0.1.0.vsix
code --install-extension sysml-0.1.0.vsix

If a server binary is present at editors/vscode/server/sysml-lsp-server when you package, it is bundled into the VSIX and the extension uses it automatically. Otherwise, point the extension at the binary you built in step 1 with the sysml.server.path setting (or put sysml-lsp-server on your PATH).

Continuous integration packages the same per-platform VSIXes (Linux x64/arm64, macOS arm64/x64, Windows x64) with the server bundled, via .github/workflows/vscode-extension.yml; a tagged build attaches them to the GitHub Release, which is where the packages above come from.

3. Check it works

Open a folder containing .sysml files. You should see syntax highlighting immediately and, once the server has indexed the workspace, squiggles for real diagnostics and working hover/completion. The SysML: Show Output command opens the server log if something looks wrong.

How the extension finds the server

In priority order:

1. the sysml.server.path setting,
2. a bundled server/ binary inside the installed extension,
3. sysml-lsp-server on the system PATH,
4. the SysML: Install/Update Language Server command, which downloads a prebuilt server from GitHub releases. Releases now publish those server binaries, so this path is live for Linux x64/arm64, macOS arm64/x64, and Windows x64.

Useful settings

All settings are under the SysML section (sysml.*):

Setting	Default	What it does
sysml.server.path	(empty)	Explicit path to sysml-lsp-server; empty means auto-detect.
sysml.server.trace	off	LSP wire tracing (messages, verbose) in the Output channel.
sysml.library.enabled	true	Load the SysML v2 standard library on startup.
sysml.validation.enabled	true	Semantic validation (constraint and type checking).
sysml.inlayHints.enabled	true	Inlay hints for inferred types and multiplicities.
sysml.formatting.enabled	true	Document formatting.
sysml.workspace.maxIndexFiles	500	Cap on indexed workspace files (0 = unlimited).

What you get

Everything the language server provides — diagnostics as you type, semantic highlighting on top of the extension’s TextMate grammars, completion, hover, navigation, rename, formatting, code actions, and inlay hints. The full capability list, checked against the server’s live initialize response, is on the language server page.

The extension additionally ships snippets for common SysML/KerML constructs and JSON-schema validation for .project.json / .workspace.json / .meta.json manifests.

Experimental / partial support — the extension is deliberately thin right now: the diagram webview, simulation panels, and debug adapter were removed during the renderer rework and will return with the new React-SVG renderer. Diagrams are available today through the CLI export and the embeddable viewer, and model execution through the CLI and runtime.

Other editors

sysml-lsp-server is a standard LSP server, so any editor with an LSP client — Neovim, Helix, Emacs, Zed, and the rest — can use it directly. Invocation, a worked client configuration, and the WebSocket bridge are on the language server page.