vscode-holocron

Visual Studio Code (and Cursor) extension for Holocron — a declarative schema and query compiler.

Activates on *.holocron.yaml files and attaches the holocron-lsp language server. Schema errors (unknown columns, duplicate aliases, unknown types, etc.) surface as red squiggles with the same rustc-style messages you'd see from the CLI — pointing at the exact YAML token at fault.

Install

1. Install the LSP binary (one of):

cargo install holocron-lsp
# or
brew install holocron-lang/holocron/holocron-lsp

2. Install the extension

VS Code → Extensions → search for Holocron → Install.

(Marketplace publish pending — until then, build from source: see Development below.)

Configuration

By default, the extension launches holocron-lsp from your PATH. Override in settings.json:

{
  "holocron.server.path": "/custom/path/to/holocron-lsp"
}

How it works

We don't declare a new language — that would lose VS Code's built-in YAML syntax highlighting. Instead, the extension attaches the LSP via a path pattern on the existing YAML language:

documentSelector: [
  { scheme: "file", language: "yaml", pattern: "**/*.holocron.yaml" }
]

VS Code provides highlighting; holocron-lsp provides diagnostics.

Development

npm install
npm run compile
# Open this folder in VS Code → F5 to launch an Extension Development Host.

To package a .vsix locally:

npx @vscode/vsce package

License

MPL-2.0 — matches the parent project.