Jj Clone Third Party

Jj Clone Third Party

Overview

Clone external repositories into the work/ directory for examination without affecting the main repository. This workflow enables source code research, dependency exploration, and upstream debugging while keeping external code isolated and gitignored.

When to Use

Use this skill when:

• Understanding how a third-party dependency implements a feature
• Researching API usage patterns or behavior in upstream libraries
• Debugging issues that might originate in dependencies
• Examining source code of tools or libraries used in the project
• Exploring alternative libraries before adding them as dependencies

Workflow

1. Identify the Repository

Determine the Git URL for the repository to examine. Common sources:

• GitHub: https://github.com/owner/repo
• GitLab: https://gitlab.com/owner/repo
• Package registries often link to source repositories

2. Clone into work/ Directory

Use jj git clone to clone the repository into work/:

jj git clone <repository-url> work/<descriptive-name>

Examples:

# Clone tokio to understand async runtime internals
jj git clone https://github.com/tokio-rs/tokio work/tokio

# Clone serde to examine serialization implementation
jj git clone https://github.com/serde-rs/serde work/serde

# Clone Buck2 to understand build system behavior
jj git clone https://github.com/facebook/buck2 work/buck2

Important: The clone is completely isolated from the main repository's history. It's stored under work/ which is gitignored, so it won't affect version control.

3. Examine the Code

Navigate into the cloned directory and use standard tools:

cd work/<repo-name>

# Search for specific functions or patterns
rg "pattern" .

# Read specific files
cat path/to/file

# Explore directory structure
tree -L 2

Alternatively, use absolute paths from the repository root:

# Search without changing directory
rg "pattern" work/<repo-name>

# Read files using absolute paths
cat work/<repo-name>/path/to/file

4. Clean Up When Done

Remove the cloned repository when the examination is complete:

rm -rf work/<repo-name>

The repository is not tracked by version control, so deletion won't affect the main repository.

Best Practices

Use Descriptive Names

Choose clear directory names that indicate the purpose:

• work/tokio - Good: immediately clear what it contains
• work/async-research - Better if examining multiple async libraries
• work/temp - Poor: unclear purpose

Navigate Efficiently

Prefer absolute paths from the repository root over changing directories:

# Preferred: stay in repo root
rg "Runtime::new" work/tokio/tokio/src

# Alternative: change directory
cd work/tokio && rg "Runtime::new" tokio/src

Leverage Existing Tools

Use Read, Grep, and Glob tools to examine cloned code efficiently:

• Grep for searching patterns across files
• Read for viewing specific files
• Glob for finding files by pattern

Document Findings

When examining third-party code to solve a problem, document key findings before cleanup:

• Note relevant file paths and line numbers
• Copy important code snippets into notes or comments
• Record insights about how the dependency works

Limitations

• No version control integration: The clone is a separate jj repository, not integrated with the main repo's history
• Manual cleanup required: The repository remains in work/ until manually deleted
• Not suitable for modifications: For testing patches to upstream, use the jj-graft-third-party skill instead

Related Skills

• jj-graft-third-party - For integrating third-party repos to test patches
• jj-workspace-experiments - For creating isolated workspaces to test changes