Dprint (dprint) for Zed

This repository contains a Zed extension that wires Zed’s Language Server support to the dprint CLI running in LSP mode.

The extension does not implement formatting itself. It launches dprint lsp (by default) and lets Zed talk to it via the Language Server Protocol.

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How it works

Language server id

The language server id is dprint (as defined in extension.toml). Any Zed lsp configuration you apply must be under:

• lsp.dprint

Binary resolution order (truthy to the code)

When Zed asks the extension to start the language server, the extension resolves which dprint executable to run in this order:

1. Zed settings override: if you configured lsp.dprint.binary.path, that path is used.
2. Workspace node_modules install: if your worktree indicates you use dprint and node_modules/.bin/dprint exists, that path is used.
   • “Indicates you use dprint” means:
     • package.json contains dprint in dependencies or devDependencies, or
     • deno.json contains dprint in imports
   • Be sure to run npm install or equivalent to install dprint in node_modules. As Zed extension host does not have the permission to check if a binary is there.
3. System PATH: if dprint is found via which, it’s used.
4. Auto-install fallback: if none of the above apply, the extension downloads the latest stable release from dprint/dprint GitHub releases and runs it.

Notes:

• The auto-installed binary is downloaded as a GitHub release zip appropriate for your OS + CPU architecture.
• x86 (32-bit) is not supported by the auto-installer; in that case you must provide a dprint binary yourself.

Arguments

• If you set lsp.dprint.binary.arguments, those arguments are used.

• Otherwise the extension starts dprint with:

• ["lsp"]

So by default it runs:

• dprint lsp

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Supported languages

Zed will attempt to use this language server for the languages declared in extension.toml:

• JavaScript
• TypeScript
• TSX
• JSON
• JSONC
• Markdown
• TOML
• CSS
• SCSS
• LESS
• HTML
• Vue.js
• Svelte
• Astro
• Angular
• Twig
• GraphQL
• YAML
• PHP
• Python

Whether formatting works for a given file still depends on your dprint configuration and plugins.

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Configuration

1) Recommended: pin the dprint binary Zed should run

When troubleshooting, explicitly point Zed at the binary and arguments you want.

Example settings.json:

{
  "lsp": {
    "dprint": {
      "binary": {
        "path": "/absolute/path/to/dprint",
        "arguments": ["lsp"]
      }
    }
  }
}

If you omit arguments, the extension defaults to ["lsp"].

2) “Extension settings” passed to the server

This extension currently does not add or forward custom LSP settings to dprint.

If you see examples referencing settings like config_path, require_config_file, requireConfiguration, or configurationPath, those are not implemented by this codebase.

What actually happens today:

• The extension only provides Zed a command + args (and no extra environment variables).
• dprint discovers configuration the same way it normally does when you run it (for example, by finding dprint.json / .dprint.json according to dprint’s own rules).

If you need non-default config discovery behavior, you currently must accomplish that via:

• running dprint from an environment where it can find the desired config, or
• using a wrapper script/binary and configuring lsp.dprint.binary.path to point to that wrapper (advanced).

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Auto-install behavior (details)

If the extension auto-installs dprint, it:

• checks the latest stable GitHub release from dprint/dprint
• downloads the matching zip asset for your platform
• removes older dprint-* directories/files in the extension working directory
• runs the downloaded dprint binary

This is meant as a convenience fallback so the extension can work even when dprint is not already installed.

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Troubleshooting

The server fails to start

Most common causes:

• The configured binary isn’t executable or isn’t the dprint you expect.
• The binary arguments aren’t correct (if you overrode them).
• You’re on 32-bit (x86) and relying on auto-install (unsupported).

Quick checks:

• Run the exact command Zed would run (for example dprint lsp) in a terminal.
• Temporarily set lsp.dprint.binary.path to a known-good dprint and keep arguments as ["lsp"].

Formatting doesn’t change files

If the language server starts but formatting seems ineffective, validate your dprint configuration and plugins by running dprint fmt manually in the same worktree and ensuring it produces the expected output.

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Development

Prerequisites

• Rust toolchain (stable is fine)
• wasm32-wasip2 target (Zed loads Rust extensions as WASM):

rustup target add wasm32-wasip2

Build/check

cargo check

Load as a dev extension in Zed

1. Open Zed
2. Run zed: install dev extensions
3. Select the repository directory
4. After changes: open zed: extensions, find the extension, and click Rebuild

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License

MIT