Language support

Sirius uses the Language Server Protocol to power autocomplete, hover, go-to-definition, diagnostics and refactor hints.

Bundled servers

Sirius ships a curated catalog of ~45 languages — the full core plus must-have ecosystem languages — and installs the matching language server on demand the first time you open a file:

Language	Server	Notes
Python	pyright + Sirius extras	Uses your project’s pyproject.toml
TypeScript / JavaScript	typescript-language-server	Honors tsconfig.json
Rust	rust-analyzer	Cargo workspace aware
Go	gopls	Go modules
C / C++	clangd	Generates compile_commands.json
HTML / CSS	vscode-langservers-extracted
Kotlin	kotlin-language-server	brew install kotlin-language-server
Scala	metals	cs install metals (coursier)
Dart	dart language-server	Ships with the Dart SDK
Zig	zls	scoop install zls / brew install zls
Nim	nimlangserver	nimble install nimlangserver

A handful of languages have no installable standalone server and rely on a toolchain you already have: R (Rscript -e "install.packages('languageserver')"), Makefile (no LSP — highlighting + tasks only), MATLAB (server ships with MATLAB), and GDScript (LSP is built into the running Godot editor).

The source of truth for every supported language, its extensions and its install plan is gui/languages/catalog.yaml in the repo.

Add a custom server

Preferences → Languages → Servers → Add:

{
  "id": "elixir",
  "extensions": ["ex", "exs"],
  "command": ["elixir-ls"]
}

Restart the LSP host (Ctrl+Shift+P → LSP: Restart).

Performance notes

• Sirius lazy-loads servers per project, not per file.
• Each server runs in its own process, sandboxed to the project root.
• If a server hangs, the Indexing indicator turns red and you can kill it from Ctrl+Shift+P → LSP: Servers….