You've probably seen that trending post — "I Asked AI to Write My Commit Messages and It Was Embarrassing."
Same. But instead of accepting embarrassing output, I fixed it.
Here's the thing: the problem isn't AI writing commit messages. The problem is how you ask it. One clear system prompt + the actual diff = surprisingly good results.
The Setup
No new packages. No API key. If you have Claude Code, you're already set.
#!/usr/bin/env python3
import subprocess
SYSTEM = (
"You are a git commit message generator. "
"Output ONLY the commit message — no explanation, no markdown, no quotes. "
"Follow Conventional Commits: type(scope): subject. "
"Types: feat, fix, docs, style, refactor, test, chore. "
"Subject: imperative, lowercase, max 72 chars."
)
diff = subprocess.check_output(["git", "diff", "--staged"], text=True)
if not diff.strip():
print("Nothing staged. Run `git add` first.")
raise SystemExit(1)
msg = subprocess.check_output(
["claude", "-p", SYSTEM + "\n\n" + diff],
text=True,
).strip()
print(msg)
That's it. 20 lines. Uses the claude CLI under the hood — no API key, no config, just your existing Claude Code OAuth session.
Why It Works
The system prompt does the heavy lifting. Three constraints:
-
Output ONLY the commit message— no preamble, no explanation -
Follow Conventional Commits—feat,fix,chore, etc. -
max 72 chars— keeps it readable in git log
The diff is the context. You're not asking "write a commit message". You're asking "given these exact changes, what happened?" That's a much more answerable question.
Usage
# No setup needed if you have Claude Code. Just:
git add .
python /path/to/git_commit.py
# → feat(server): add AI commit message generator via Claude CLI
Or wire it into a git alias:
git config --global alias.ai '!python /path/to/git_commit.py'
# git ai
The Results
Before:
update stuff
fix bug
WIP
added the thing
After:
feat(api): add generate_commit_message tool to MCP server
fix(auth): handle expired token on refresh
refactor(db): extract query builder into separate module
As an MCP Tool Too
I also wrapped it as an MCP tool so Claude Code can call it directly from any conversation:
@mcp.tool()
def generate_commit_message(diff: str) -> str:
"""Generate a Conventional Commits message from a git diff string."""
full = SYSTEM + "\n\n" + diff
return subprocess.check_output(["claude", "-p", full], text=True).strip()
Full project: github.com/enjoy-kumawat/my-git-manager
20 lines. No new dependencies. No API key. Conventional Commits every time.
The embarrassing part was waiting this long to build it.
United States
NORTH AMERICA
Related News
Why Every Developer Needs a Strong Test Suite (Even If You Hate Writing Tests)
23h ago
SOLSTICE SIDEBAR - AI INCIDENT DESK
1d ago
The CFO's AI Playbook: 5 Finance Automations Every Indian Business Should Run in 2026
1d ago
Passkeys in 2026: A Practical Engineering Guide to Passwordless Auth
1d ago
AWS S3 Basics for Beginners
23h ago