claude-commit: Use Claude Code to generate git commit messages, then review in your editor before committing

claude-commit.sh

#!/usr/bin/env bash
#
# claude-commit: Use Claude Code to generate a commit message for staged changes,
# then open it in the editor for review before committing.
#
# Usage: claude-commit [custom instruction]
#
# Examples:
#   claude-commit                        # Generate a standard commit message
#   claude-commit "detailed description" # Add custom instructions for Claude
#
# Prerequisites: Claude Code CLI (https://claude.com/product/claude-code)

claude-commit() {
  if ! command -v claude &> /dev/null; then
    echo "Claude Code CLI is not installed. Get it at https://claude.com/product/claude-code"
    return 1
  fi

  if git diff --cached --quiet; then
    echo "No staged changes to commit."
    return 1
  fi

  local max_subject_length=72
  local user_instruction=""
  if [[ -n "$*" ]]; then
    user_instruction="Additional instruction from the user: $*"
  fi

  local msg_file
  msg_file=$(mktemp "${TMPDIR:-/tmp}/claude-commit.XXXXXX")

  echo "Generating commit message with Claude..."
  if ! git diff --cached | claude -p \
    "Generate a git commit message for these staged changes. Output ONLY the commit message, nothing else. Rules: use conventional commit format (e.g. feat:, fix:, refactor:). The first line MUST be at most ${max_subject_length} characters including the prefix — this is a hard limit, truncate or rephrase if needed. Optionally follow with a blank line and a longer description. ${user_instruction}" \
    > "$msg_file"; then
    echo "Failed to generate commit message."
    rm -f "$msg_file"
    return 2
  fi

  git commit --edit --file="$msg_file"
  local exit_code=$?

  rm -f "$msg_file"
  return $exit_code
}