Editor Support

Halo has a small language server (src/lsp/) and editor packages in editors/.

Language server

The server provides:

• Diagnostics: syntax errors at the offending token, plus every halo validate error and warning at its line.
• Hover: details for declarations (model, system prompt, provider, policy rules) and for operators.
• Completion: keywords and the names declared in the file. It also offers System methods after System., directives after @, providers after tool X :, rule names on policy lines, and categories inside Block( / Redact(.

It does not provide go-to-definition, rename, completion of context.data fields, or a debugger. For step-by-step output, use halo debug.

VS Code

editors/vscode contains a syntax grammar and the language-server client. It isn't on the Marketplace. Build and install it from the repository:

bun run package:vsx                                 # bundles the server and builds a .vsix
code --install-extension editors/vscode/halo-dsl-0.1.0.vsix

Zed

editors/zed is a Zed extension with a tree-sitter grammar for highlighting, brackets, and indentation. It has no language server. See editors/zed/README.md to install it as a dev extension.

Sublime Text

editors/sublime/Halo.sublime-syntax provides syntax highlighting. Copy it into your Sublime Packages/User directory.

Docs

This site highlights ```halo blocks with the VS Code TextMate grammar.