Git Commit Trailers

Git Commit Trailers

When to Use This Skill

Structured key-value metadata at the end of commit messages. Trailers drive release-please automation, attribution, and issue linking.

When to Use

Release-Please Trailers

These trailers directly control version bumps and changelog generation.

BREAKING CHANGE

Triggers a major version bump. Both forms are recognized:

feat(api)!: redesign authentication endpoints

BREAKING CHANGE: /v1/users endpoint removed. Use /v2/users instead.

Both BREAKING CHANGE: and BREAKING-CHANGE: (hyphenated) are recognized.

Release-As

Force a specific version in the next release. Case-insensitive.

git commit --allow-empty -m "chore: release 2.0.0" -m "Release-As: 2.0.0"

Multiple Changes in One Commit

A single commit can produce multiple changelog entries via footer messages:

feat: add v4 UUID to crypto

This adds support for v4 UUIDs to the library.

fix(utils): unicode no longer throws exception
  BREAKING-CHANGE: encode method no longer throws.

feat(utils): update encode to support unicode

Additional conventional commit messages must be at the bottom of the commit body.

BEGIN_COMMIT_OVERRIDE

Edit a merged PR body to override its changelog entry. Only works with squash-merge.

BEGIN_COMMIT_OVERRIDE
feat: add ability to override merged commit message

fix: correct typo in error message
END_COMMIT_OVERRIDE

Use when a commit message needs correction after merge without reverting.

Attribution Trailers

Issue references (Fixes #N, Closes #N, Refs #N) are also trailers — see github-issue-autodetect skill.

Decision Tree

What trailers does this commit need?
├─ Breaking API change? → BREAKING CHANGE: <description>
├─ Force specific version? → Release-As: x.x.x
├─ AI-assisted code? → Co-authored-by: Claude <noreply@anthropic.com>
├─ DCO-required project? → Signed-off-by: Name <email>
├─ Fixes/closes an issue? → See github-issue-autodetect
└─ None of the above → No trailers needed

Detect DCO requirement:

git log -20 --format='%B' | git interpret-trailers --parse | grep -c "Signed-off-by"

Detecting Project Conventions

Scan recent commits to discover what trailers a project uses:

# Parse all trailers from recent commits
git log -20 --format='%B' | git interpret-trailers --parse

# List unique trailer types
git log -20 --format='%B' | git interpret-trailers --parse | sort -u -t: -k1,1

# Count trailer usage
git log -50 --format='%B' | git interpret-trailers --parse | cut -d: -f1 | sort | uniq -c | sort -rn

Always match existing project conventions before adding new trailer types.

Composing Trailers with git interpret-trailers

# Add a trailer to a message
echo "feat(auth): add OAuth2" | git interpret-trailers \
  --trailer "Co-authored-by: Claude <noreply@anthropic.com>"

# Add multiple trailers
echo "feat(auth): add OAuth2" | git interpret-trailers \
  --trailer "Co-authored-by: Claude <noreply@anthropic.com>" \
  --trailer "Signed-off-by: Dev <dev@example.com>"

# Parse trailers from last commit
git log -1 --format='%B' | git interpret-trailers --parse

Agentic Optimizations