Zed Mojo#

A Zed extension providing Mojo language support with syntax highlighting and LSP integration.

Fork of bajrangCoder/zed-mojo, modified to look up mojo-lsp-server directly from PATH instead of depending on pixi. This makes it compatible with Nix-based environments using direnv.

Features#

• Syntax highlighting via tree-sitter-mojo
• Outlines and text objects
• Language Server Protocol (LSP) support

How it works#

The extension simply looks up mojo-lsp-server in PATH via worktree.which(). With Zed's load_direnv setting enabled, any Mojo installation provided by direnv/Nix will be picked up automatically.

Recommended Zed settings:

{
  "load_direnv": "direct",
  "languages": {
    "Mojo": {
      "formatter": {
        "external": {
          "command": "mojo",
          "arguments": ["format", "-q", "-"]
        }
      },
      "format_on_save": "on"
    }
  }
}

Project structure#

zed-mojo/
├── src/
│   └── mojo.rs                    # Extension entry point — LSP binary lookup
├── languages/
│   └── mojo/
│       ├── config.toml            # Language configuration (file types, brackets, indentation)
│       ├── highlights.scm         # Syntax highlighting queries
│       ├── brackets.scm           # Bracket matching queries
│       ├── indents.scm            # Auto-indentation queries
│       ├── outline.scm            # Symbol outline queries
│       ├── embedding.scm          # Embedding queries
│       ├── overrides.scm          # Scope override queries
│       └── textobjects.scm        # Text object queries (functions, classes, comments)
├── extension.toml                 # Extension metadata and grammar/LSP declarations
├── Cargo.toml                     # Rust project configuration
├── Cargo.lock                     # Dependency lock file
└── default.nix                    # Nix flakelight module (package + dev shell)

Installation#

This extension is installed as a Zed dev extension via Home Manager. The activation script copies the source into ~/.local/share/zed/dev_extensions/mojo, where Zed compiles it to WASM.

Development#

Enter the dev shell (requires Nix):

nix develop .#zed-mojo

This provides a Rust toolchain with the wasm32-wasip2 target needed to compile the extension.