URDF

URDF for Zed

URDF language support for Zed with:

• Syntax highlighting
• Outline / structure view
• Auto indentation
• Context-aware completions for common URDF tags, attributes, and values

This extension targets .urdf files and builds on top of the XML Tree-sitter grammar plus an external URDF language server.

Features

• Recognizes .urdf files as the URDF language
• Reuses the XML Tree-sitter grammar for parsing
• Provides syntax highlighting through Tree-sitter queries
• Provides outline support for URDF/XML elements
• Shows name context in outline entries for robot, link, and joint
• Provides completions for common URDF tags such as:
  • robot
  • link
  • joint
  • visual
  • collision
  • inertial
  • geometry
  • origin
  • parent
  • child
  • axis
  • limit
  • material
  • mesh
• Provides completions for common URDF attributes and values
• Supports both block-style and self-closing completions for tags like link and material

Installation

For normal users:

1. Install the extension in Zed
2. Open a .urdf file
3. The extension will look for a language server binary whose version exactly matches the extension version
4. If that exact-version binary is not already cached, the extension downloads the matching GitHub Release asset for the same version

This extension intentionally uses a strict version lock between the extension and the language server.

That means:

• extension version 0.1.0 only accepts language server release tag v0.1.0
• extension version 0.1.1 only accepts language server release tag v0.1.1
• the extension does not use the latest release automatically
• the extension does not silently fall back to a different installed server version

Version Lock Policy

The repository follows these rules:

• Cargo.toml version
• extension.toml version
• urdf-language-server/Cargo.toml version
• Git tag name without the leading v

must all be identical.

Examples:

• extension version: 0.1.0
• language server crate version: 0.1.0
• Git tag: v0.1.0

At runtime, the extension downloads only the release with tag v0.1.0 when the extension version is 0.1.0.

Release Assets

Expected release asset names:

• urdf-language-server-vX.Y.Z-x86_64-unknown-linux-musl.tar.gz
• urdf-language-server-vX.Y.Z-x86_64-apple-darwin.tar.gz
• urdf-language-server-vX.Y.Z-aarch64-apple-darwin.tar.gz
• urdf-language-server-vX.Y.Z-x86_64-pc-windows-msvc.zip

Each archive must contain the executable at the archive root:

• urdf-language-server
• urdf-language-server.exe on Windows

Development

Prerequisites

Install Rust with rustup.

Install as a Dev Extension in Zed

1. Open Zed
2. Open the command palette
3. Run zed: install dev extension
4. Select this repository folder

After changing the extension, open the Extensions page and click Rebuild for the dev extension.

Local Testing Without GitHub Release

You do not need to publish a GitHub Release every time you modify the language server during development.

With the strict version-locked setup used by this extension, the runtime behavior is:

1. The extension first checks whether a language server binary for the exact same version already exists in the local versioned cache directory
2. Only if that exact-version binary is missing does it try to download the matching GitHub Release asset for the same version tag

That means local development can use a manually built binary, as long as:

• the extension version and language server version are the same
• the binary is placed at the expected versioned cache path

Keep versions in sync

Before local testing, make sure these versions are identical:

• Cargo.toml
• extension.toml
• urdf-language-server/Cargo.toml

For example, if the version is 0.1.0, then all three files should use 0.1.0.

Build the language server locally

From the repository root:

cargo build --manifest-path ./urdf-language-server/Cargo.toml --release

Put the binary into the expected local cache directory

Create the versioned cache directory expected by the extension:

Linux:

~/.local/share/zed/extensions/work/.zed-urdf/<version>/

macOS:

~/Library/Application Support/zed/extensions/work/.zed-urdf/<version>/

Windows:

%LOCALAPPDATA%\Zed\extensions\work\.zed-urdf\<version>\

Then copy the locally built binary into that directory.

Linux

If you build for the default host target:

ZED_EXT_DIR="$HOME/.local/share/zed/extensions/work/urdf/.zed-urdf/0.1.0"
mkdir -p "$ZED_EXT_DIR"
cp urdf-language-server/target/release/urdf-language-server "$ZED_EXT_DIR/urdf-language-server"
chmod +x "$ZED_EXT_DIR/urdf-language-server"

If you explicitly build a target triple, your output path may instead look like this:

ZED_EXT_DIR="$HOME/.local/share/zed/extensions/work/urdf/.zed-urdf/0.1.0"
mkdir -p "$ZED_EXT_DIR"
cp urdf-language-server/target/x86_64-unknown-linux-gnu/release/urdf-language-server "$ZED_EXT_DIR/urdf-language-server"
chmod +x "$ZED_EXT_DIR/urdf-language-server"

macOS

ZED_EXT_DIR="$HOME/Library/Application Support/zed/extensions/work/urdf/.zed-urdf/0.1.0"
mkdir -p "$ZED_EXT_DIR"
cp urdf-language-server/target/release/urdf-language-server "$ZED_EXT_DIR/urdf-language-server"
chmod +x "$ZED_EXT_DIR/urdf-language-server"

Windows (PowerShell)

$ZedExtDir = "$env:LOCALAPPDATA\Zed\extensions\work\.zed-urdf\0.1.0"
New-Item -ItemType Directory -Force -Path $ZedExtDir | Out-Null
Copy-Item "urdf-language-server\target\release\urdf-language-server.exe" "$ZedExtDir\urdf-language-server.exe"

Replace 0.1.0 with your actual current extension version.

Recommended local test workflow after changing the language server

When you modify urdf-language-server/src/main.rs:

1. Keep all versions unchanged if you are just testing local behavior
2. Run the local release build
3. Copy the new binary into .zed-urdf/<version>/
4. Rebuild the dev extension in Zed
5. Reopen a .urdf file and verify completions

Testing a version bump locally

If you want to test a new version locally, such as moving from 0.1.0 to 0.1.1:

1. Update these files to 0.1.1:

   • Cargo.toml
   • extension.toml
   • urdf-language-server/Cargo.toml

2. Build the language server again

3. Copy the binary into .zed-urdf/0.1.1/

4. Rebuild the dev extension in Zed

The extension will then use only the 0.1.1 binary and will not reuse the old 0.1.0 cache.

When is GitHub Release actually needed?

A GitHub Release is only needed when you want to test the real published download path:

• remove the local cached binary for the current version
• keep the same version
• create the matching Git tag such as v0.1.0
• publish the release assets
• let the extension download that exact-version asset automatically

Publishing Notes

This repository keeps the language server source code, but the published Zed extension does not ship the server binary inside the extension package.

Instead:

• GitHub Actions builds versioned language server binaries
• those binaries are uploaded as GitHub Release assets
• the extension downloads only the asset whose tag exactly matches the extension version

Troubleshooting

If the extension does not seem to work:

• open Zed.log using zed: open log
• or launch Zed from the command line with:

zed --foreground

This usually shows more detailed extension and language server logs during development.

You may also want to check:

• whether the three version fields are exactly the same
• whether the local binary exists under .zed-urdf/<version>/
• whether the binary name is correct for your platform
• whether the binary is executable on Unix-like systems

Project Structure

.
├── .github/
│   └── workflows/
│       ├── check-version-sync.yml
│       └── release-language-server.yml
├── README.md
├── extension.toml
├── Cargo.toml
├── src/
│   └── lib.rs
├── languages/
│   └── urdf/
│       ├── config.toml
│       ├── highlights.scm
│       ├── indents.scm
│       └── outline.scm
└── urdf-language-server/
    ├── Cargo.toml
    └── src/
        └── main.rs

Example

<?xml version="1.0"?>
<robot name="demo_robot">
  <link name="base_link" />

  <link name="arm_link">
    <visual>
      <geometry>
        <box size="1 1 1" />
      </geometry>
    </visual>
  </link>

  <joint name="base_to_arm" type="revolute">
    <parent link="base_link" />
    <child link="arm_link" />
    <origin xyz="0 0 0.1" rpy="0 0 0" />
    <axis xyz="0 0 1" />
    <limit lower="-1.57" upper="1.57" effort="100" velocity="1.0" />
  </joint>
</robot>

Notes

• This extension currently uses the XML grammar for parsing URDF documents
• Completions are provided by the external custom URDF language server
• The completion engine is designed specifically for common URDF authoring workflows, rather than full XML Schema/XSD validation

Acknowledgements

This project builds on and draws inspiration from:

• tree-sitter-xml
• sweetppro/zed-xml

Many thanks to the maintainers and contributors of those projects.

License

This project is licensed under the Apache License 2.0.