I Built a CLI Tool That Writes My Commit Messages

--- title: I Built a CLI Tool That Writes My Commit Messages published: true tags: git, ai, cli, productivity --- Hello guys! We've all been there. You just finished a feature, you're ready to commit, and then you stare at the terminal for 30 seconds trying to come up with a decent commit message. Sometimes I'd spend more time thinking about the message than writing the actual code. So I did what any developer would do. I automated it. ## How it started I already had Claude installed on my machine. One day I realized I could just pipe my git diff into it and ask for a commit message. So I added this little function to my `.zshrc`: ```bash gpm() { git diff HEAD | claude -p "propose a conventional commit message for these changes. output only the message, nothing else." } ``` That was it. Run `gpm`, get a message, copy paste it. Simple. Then I wanted to go further. Why not commit directly with the proposed message? ```bash gac() { msg=$(git diff HEAD | claude -p "propose a conventional commit message for these changes, one line only. output only the message, nothing else.") echo "\n$msg\n" read "confirm?Commit with this message? [y/N] " if [[ "$confirm" == "y" ]]; then git add -A && git commit -m "$msg" fi } ``` This worked great for a while. But I kept wanting more. What about code review? PR descriptions? What if I could choose the model? What about using the API directly instead of going through the CLI? At some point I realized these shell functions were becoming a full tool. So I decided to build one. ## Meet claude-git [claude-git](https://github.com/lucasnevespereira/claude-git) is a CLI that reads your git diff and sends it to Claude to generate commit messages, review code, write PR descriptions, and more. It's written in bash, runs entirely in your terminal, and installs in one command. ```bash curl -fsSL https://raw.githubusercontent.com/lucasnevespereira/claude-git/main/install.sh | bash ``` Let's go through the main features. ## Proposing a commit message The most basic command. Stage your changes, run `claude-git msg`, and you get a conventional commit message. ```bash claude-git msg # -> feat: add user authentication with JWT tokens ``` That's it. It reads the diff, sends it to Claude, and outputs a message. You can copy it or use it however you want. ## Committing directly If you don't want to copy paste, `claude-git commit` will propose a message and ask you to confirm before committing. ```bash claude-git commit feat: add user authentication with JWT tokens Commit with this message? [y/N] y ``` And if you're feeling confident and want to skip the confirmation: ```bash claude-git commit -y ``` ## Prefix mode At work we often need to prefix commits with a ticket ID. Something like `PROJ-42: fix login redirect`. I got tired of typing the prefix manually so I added a `prefix` command that auto detects the ticket from your branch name. If your branch is called `feature/PROJ-42-login-fix`, running `claude-git prefix` will automatically extract `PROJ-42` and prepend it to the message. ```bash claude-git prefix # -> PROJ-42: fix login redirect after session expiry ``` You can also pass the prefix manually: ```bash claude-git prefix PROJ-42 ``` ## Code review Before pushing, I sometimes want a quick sanity check. The `review` command sends your diff to Claude and asks it to flag bugs, security issues, or logic errors. ```bash claude-git review ``` It's not a replacement for a real code review, but it's useful to catch obvious mistakes before opening a PR. ## PR descriptions Writing PR descriptions is another thing that takes longer than it should. The `pr` command looks at all commits and the full diff against your base branch and generates a structured description. ```bash claude-git pr ``` By default it compares against `main`, but you can specify another branch: ```bash claude-git pr develop ``` ## Explaining changes Sometimes you come back to some changes you made yesterday and forgot what they do. The `explain` command gives you a quick summary. ```bash claude-git explain # -> These changes add rate limiting to the API endpoints using a token bucket... ``` ## Short aliases I like short commands. The installer automatically adds aliases to your shell config: ```bash cg # claude-git cgm # claude-git msg cgc # claude-git commit cgcy # claude-git commit --yes cgrev # claude-git review cgpr # claude-git pr cgex # claude-git explain cgpx # claude-git prefix ``` So in practice, committing with AI looks like this: ```bash cgcy ``` Three characters and you're done. ## Configuration You can configure the model, the max diff size, and whether to use the API directly or go through the Claude CLI. ```bash claude-git config model sonnet # use a more capable model claude-git config api_key sk-ant-... # use API calls directly (faster) claude-git config max_lines 5000 # handle larger diffs ``` By default it uses Haiku which is fast and cheap. If you set an API key, it will call the Anthropic API directly instead of going through Claude Code, which is noticeably faster. The config lives in `~/.claude-git` as a simple key=value file. Nothing fancy. ## Why bash? I get this question a lot. Bash is not glamorous. But for a tool that wraps git commands and pipes text to an API, it's actually the perfect fit. No compile step, no dependencies, no runtime. It just works on any machine that has bash and git. The entire tool is a single file. That makes it easy to install, easy to read, and easy to contribute to. ## What I learned Building this tool taught me a few things. First, sometimes the best projects come from automating your own annoyances. I didn't sit down and plan this. It grew from a two line function in my shell config. Second, keeping things simple pays off. bash is not the fanciest choice but it made the tool easy to distribute and maintain. No build system, no package manager drama. And finally, AI is really good at reading diffs. The commit messages Claude generates are genuinely useful. Most of the time I accept them as is. ## Try it out If you want to give it a try: ```bash curl -fsSL https://raw.githubusercontent.com/lucasnevespereira/claude-git/main/install.sh | bash ``` The repo is here: [github.com/lucasnevespereira/claude-git](https://github.com/lucasnevespereira/claude-git) It's open source under MIT. Feedback and contributions are welcome. Hope you find it useful!