<!-- Copyright 2025-2026 Richard Shade. Licensed under Apache-2.0. -->
<!-- SPDX-License-Identifier: Apache-2.0 -->
Commitlint
Validate commit messages follow the
Conventional Commits specification.
Enables automatic changelog generation, semantic versioning, and clean git
history.
What this skill does
- Checks if
@commitlint/cli and @commitlint/config-conventional are
installed; installs them if missing.
- Detects project-specific commitlint configuration or falls back to a
sensible default config.
- Validates commit messages for type, scope, subject, body, and footer
format.
- Reports errors with specific fixes and examples.
Installation check
# Check if commitlint is available
npx commitlint --version 2>/dev/null
If not installed, install globally:
npm install -g @commitlint/cli @commitlint/config-conventional
If installation fails (permissions, no npm), stop validation and report
the issue with remediation steps:
- Use
sudo npm install -g ... or fix npm permissions
- Use a Node version manager (nvm, volta, fnm)
- Install Node.js if not present
Do not silently skip validation.
Config detection priority
commitlint.config.js in project root.commitlintrc.json in project root.commitlintrc.yaml in project root.commitlintrc in project rootcommitlint field in package.json- Default config (see
references/conventional-commits.md)
If no project config exists, create a temporary .commitlintrc.json using
the default config from the reference document before running validation.
Validation workflow
1. Check commitlint installation
├─ Installed → continue
└─ Missing → install, then continue (fail if install fails)
2. Detect project config
├─ Found → use it
└─ Not found → use default config from references/
3. Run validation
├─ From a string:
│ echo "<message>" | npx commitlint
├─ From a file:
│ cat <file> | npx commitlint
└─ From last git commit:
git log -1 --format=%B | npx commitlint
4. Report results
├─ Valid → confirm and proceed
└─ Invalid → show errors, suggest fixes, re-validate after correction
Validation methods
Validate a commit message string
echo "feat(api): add login endpoint" | npx commitlint
Validate contents of a file
cat path/to/message-file.txt | npx commitlint
Validate the most recent git commit
git log -1 --format=%B | npx commitlint
Error handling
Install failure
If commitlint cannot be installed, report the error and provide
remediation steps. Do not proceed with validation.
Invalid message
When validation fails, report each error with:
- The rule that failed (e.g.,
type-enum, header-max-length)
- What was wrong (e.g., type
feature is not allowed)
- A concrete fix (e.g., use
feat instead)
Example:
Validation failed:
1. type-enum: type 'feature' is not allowed
Allowed: feat, fix, docs, style, refactor, perf, test, build, ci,
chore, revert
Fix: use 'feat' instead of 'feature'
2. header-max-length: header is 72 characters (max 50)
Fix: shorten to 'feat: add user authentication with JWT'
After reporting errors, suggest a corrected message and re-validate.
Format reference
See references/conventional-commits.md for the full Conventional Commits
format specification, type descriptions, rules, default config, and
examples.