Connect: the editor

Arxo Law (arxo.law) is the extension for VS Code and Cursor. It highlights .law files, shows compiler diagnostics, and renders the compiler’s output: outline, proof, why-not. It has no semantics of its own. The repository also contains a separate law-lsp language server.

Asking an already formalized canon from an agent is a different door: Connect an AI assistant (MCP).

Install

Install Arxo Law from the Visual Studio Marketplace (VS Code) or Open VSX (Cursor), then reload the window. Identifier: arxo.law.

code --install-extension arxo.law

What runs without Rust

The package ships a WebAssembly build of the compiler. With that bundle present, parse, check, layer, lower, expand, test, explain, why-not and graph run in the editor without a native binary on the machine.

What still needs law-cli

These commands go through the native compiler. Put law-cli on PATH, or set law.lawcPath:

• format, including format-on-save
• package-root
• semantic hash
• eval on a vector
• the strict imports check

The default engine setting is auto: WebAssembly when the bundle is found, otherwise the binary.

Language server status

The provider parity checks passed for all twelve provider rows on 24.09.2026, so a local build of the extension hands hover, navigation, references, completion, inlays, code actions, symbols, semantic tokens, rename, formatting and workspace symbols to law-lsp — all 12 JS providers are torn down. With the ledger fully PASS the client also enables backgroundAnalysis: true, so diagnostics move to the server as well (apps/editors/vscode/lib/lsp-client.js); the JavaScript adapter keeps diagnostics only while a row is not yet PASS. Rename is certified only for package-private declarations with an explicit @id that the compiler honours; everything else is refused with a reason. The published Marketplace build predates this handoff.

The extension shows compiler output; it does not decide what the law says. Read the act alongside the editor result.