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