vscode

SysML v2 / KerML for VS Code

Language support for the OMG SysML v2 and KerML textual notations, powered by the sysmlv2 language server (sysmlv2 lsp).

• Exact, dialect-aware highlighting via semantic tokens. Keywords in this language are contextual — part is a keyword in SysML and a legal name in KerML — so no TextMate grammar can classify them; the parser does, and this extension renders its verdict. The bundled TextMate grammar is a deliberately coarse fallback (notes, doc comments, strings, numbers) shown only until the server answers.
• Live diagnostics: parse errors with recovery and body-context validation; a configured standard library enables semantic diagnostics.
• Navigation and editing: go to definition, references, completion, hover, rename, inlay hints, code lenses, and refactoring actions from the language server. Semantic features require library context.
• Outline / breadcrumbs / sticky scroll from the document symbol tree, including anonymous members («part») and : Type [mult] details.
• Formatting via the toolkit's idempotent, note-preserving formatter.

Setup

1. Install the sysmlv2 binary somewhere on PATH (or set sysmlv2.serverPath). The default release binary includes the server; check with sysmlv2 lsp --help.

2. Build and install the extension:

   cd editors/vscode
   npm install
   npx vsce package        # produces sysmlv2-<version>.vsix
   code --install-extension sysmlv2-*.vsix

To enable semantic features, start VS Code from an environment with SYSMLV2_LIB_DIR set to an initialized sysml.library directory. The extension launches sysmlv2 lsp and inherits that environment; sysmlv2.serverPath controls only the executable. Other clients can pass --lib /path/to/sysml.library directly.

Other editors

The server is plain LSP over stdio; any client works.

Neovim (0.11+):

vim.filetype.add { extension = { sysml = "sysml", kerml = "kerml" } }
vim.lsp.config("sysmlv2", {
  cmd = { "sysmlv2", "lsp" },
  filetypes = { "sysml", "kerml" },
})
vim.lsp.enable("sysmlv2")

Helix (languages.toml):

[language-server.sysmlv2]
command = "sysmlv2"
args = ["lsp"]

[[language]]
name = "sysml"
scope = "source.sysml"
file-types = ["sysml", "kerml"]
language-servers = ["sysmlv2"]