Rust Crate Source

Rust Crate Source Explorer

This skill clones Rust crate repositories from crates.io to explore their source code. It fetches the repository URL from the crates.io API, clones to /tmp/rust-crates/, and checks out the appropriate version tag.

When to Use

Use this skill when the user:

• Wants to explore or read source code for a Rust crate
• Wants to understand how a crate is implemented
• Needs context about a Rust library's internals
• Mentions "crate source", "explore crate", "how does X crate work"
• Asks to look at the implementation of a specific crate feature

How to Use

Step 1: Fetch Crate Info

Query the crates.io API to get the repository URL and latest version:

CRATE_NAME="serde"  # replace with the actual crate name
mkdir -p /tmp/rust-crates
CRATE_INFO=$(curl -sH "User-Agent: rust-crate-explorer" "https://crates.io/api/v1/crates/$CRATE_NAME")
REPO_URL=$(echo "$CRATE_INFO" | jq -r '.crate.repository')
VERSION=$(echo "$CRATE_INFO" | jq -r '.crate.max_version')
echo "Repository: $REPO_URL"
echo "Version: $VERSION"

Step 2: Clone Repository

Clone if not already cached:

if [ ! -d "/tmp/rust-crates/$CRATE_NAME" ]; then
  git clone "$REPO_URL" "/tmp/rust-crates/$CRATE_NAME"
fi

Step 3: Checkout Version Tag

Try common tag naming patterns to match the crate version:

cd "/tmp/rust-crates/$CRATE_NAME"
git fetch --tags
git checkout "v$VERSION" 2>/dev/null || \
git checkout "$VERSION" 2>/dev/null || \
git checkout "$CRATE_NAME-$VERSION" 2>/dev/null || \
echo "No matching tag found, using HEAD"

Step 4: Explore the Source

Use Read, Glob, and Grep tools to explore the crate source at: /tmp/rust-crates/$CRATE_NAME/

For workspace crates, the main source is typically in src/ or a subdirectory matching the crate name.

Example Workflow

User asks: "How does serde handle derive macros?"

# fetch and clone
CRATE_NAME="serde"
mkdir -p /tmp/rust-crates
CRATE_INFO=$(curl -sH "User-Agent: rust-crate-explorer" "https://crates.io/api/v1/crates/$CRATE_NAME")
REPO_URL=$(echo "$CRATE_INFO" | jq -r '.crate.repository')
VERSION=$(echo "$CRATE_INFO" | jq -r '.crate.max_version')

if [ ! -d "/tmp/rust-crates/$CRATE_NAME" ]; then
  git clone "$REPO_URL" "/tmp/rust-crates/$CRATE_NAME"
fi

cd "/tmp/rust-crates/$CRATE_NAME"
git fetch --tags
git checkout "v$VERSION" 2>/dev/null || git checkout "$VERSION" 2>/dev/null || echo "Using HEAD"

Then explore with Glob/Read tools to find derive macro implementations.

Notes

• Missing repository: Some crates don't set the repository field; the API will return null
• Version tags: Not all crates tag releases; fall back to HEAD if no tag matches
• Monorepos: Large projects (tokio, serde) may have multiple crates in subdirectories
• Dependencies: Requires jq for JSON parsing
• Temp storage: Repos are stored in /tmp/rust-crates/ and will be cleaned on reboot