Co-Author Committer

A fast terminal UI tool to amend your latest git commit with co-authors.

Preview

┌ cac ─────────────────────────────────-────── v.X.Y.Z ┐
│ Amending: a1b2c3d feat: add user authentication      │
└──────────────────────────────────────────────────────┘
┌ Search contributors ─────────────────────────────────┐
│ ali                                                  │
└──────────────────────────────────────────────────────┘
┌ Contributors (3) ────────────────────────────────────┐
│ ✓ Alice Smith <alice@example.com>                    │
│ ──────────────────────────────────────────────────── │
│   Alina Mueller <alina@example.com>                  │
│   Ali Hassan <ali.hassan@example.com>                │
└──────────────────────────────────────────────────────┘
 ↑↓ navigate   Tab toggle   Enter confirm   Esc cancel

Workflow

commit → cac → push

Features

• Smart Contributor Discovery: Scans your git history to find contributors automatically
• Pinned Authors: Predefine team members in ~/.config/cac/authors — useful for teammates who haven't committed to this repo yet
• Fuzzy Search: Quickly filter contributors by name or email
• Multi-select: Add multiple co-authors at once
• Amend Mode: Modifies your latest commit in-place — no extra commits
• Fast: Built with Rust, uses libgit2 natively

Installation

Via Homebrew

brew tap tomhuettmann/tap
brew trust tomhuettmann/tap
brew install tomhuettmann/tap/cac

From Release

Download the latest release from GitHub Releases.

From Source

cargo install --path .

Usage

Run in any git repository after making a commit:

# Use current directory
cac

# Specify a repository path
cac -d /path/to/repo

Pinned Authors

Predefine authors in ~/.config/cac/authors to have them appear at the top of the contributor list. The file is created automatically on first run with a template entry.

# cac authors — add one author per line in "Name <email>" format
# Lines starting with # are comments
Alice Example <alice@example.com>
Bob Builder <bob@example.com>

Authors from this file always appear first, in file order, followed by contributors discovered from git history. Duplicates are automatically removed (matched by email, case-insensitive). Your own entry is filtered out automatically.

Controls

Key	Action
↑ / ↓	Navigate contributor list
Tab	Toggle co-author selection
Enter	Confirm and amend commit
Esc	Cancel (no changes)
Type	Fuzzy search contributors

Requirements

• macOS arm64 (Apple Silicon)
• Git installed and configured
• A git repository with at least one commit

How It Works

1. Loads pinned authors from ~/.config/cac/authors
2. Scans your entire git history for unique contributors (excluding yourself)
3. Merges the lists: pinned authors first, then git history contributors (deduplicated)
4. Presents an interactive fuzzy-searchable list
5. Amends the commit with selected Co-authored-by: trailers

Your commit message

Co-authored-by: Alice Smith <alice@example.com>
Co-authored-by: Bob Jones <bob@example.com>

Development

cargo run
cargo test
cargo build --release

License

MIT — see LICENSE.

Author

Tom Hüttmann — @tomhuettmann