commit-msg

#!/usr/bin/env sh
# Validate Conventional Commits without Node/npm.
# Enable once per clone:  git config core.hooksPath .githooks
#
# Format: <type>(optional-scope)!: <summary>
# Types: feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert|release

msg_file="$1"
if [ -z "$msg_file" ] || [ ! -f "$msg_file" ]; then
  echo "commit-msg: missing commit message file" >&2
  exit 1
fi

# First non-comment, non-empty line is the subject.
subject=$(
  grep -v '^#' "$msg_file" | sed '/^[[:space:]]*$/d' | head -n 1
)

if [ -z "$subject" ]; then
  echo "commit-msg: empty commit subject" >&2
  exit 1
fi

# Allow merge / revert subjects produced by git itself.
case "$subject" in
  Merge\ *|Revert\ *)
    exit 0
    ;;
esac

pattern='^(feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert|release)(\([a-z0-9._/-]+\))?(!)?: .+'

if ! printf '%s\n' "$subject" | grep -Eq "$pattern"; then
  cat >&2 <<'EOF'
commit-msg: subject must follow Conventional Commits

  <type>(optional-scope): <summary>

Examples:
  feat(cache): add get_or_set helper
  fix(node): restore swagger navbar versions
  docs: expand root README install section
  chore(release): bump to 2.0.2

Types: feat fix docs style refactor perf test build ci chore revert release
EOF
  exit 1
fi

# Soft limit: keep the subject scannable in git log.
len=$(printf '%s' "$subject" | wc -c | tr -d ' ')
if [ "$len" -gt 100 ]; then
  echo "commit-msg: subject is ${len} chars (max 100)" >&2
  exit 1
fi

exit 0