Strip AI Co-Authored-By Lines Implementation Plan¶

For agentic workers: REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (- [ ]) syntax for tracking.

Goal: Add a commit-msg lefthook command that silently removes Co-Authored-By: trailers from AI agents (Claude, Copilot, Gemini, ChatGPT, OpenAI, Cursor) before commitlint runs.

Architecture: A single perl -i -pe one-liner is added as a new strip-ai-coauthors command in the commit-msg section of lefthook.yml, with priority: 1 so it runs before the existing commitlint command (priority: 2). No new files are created.

Tech Stack: lefthook, perl (available on macOS and Linux by default)

Task 1: Add strip-ai-coauthors command to lefthook.yml¶

Files: - Modify: lefthook.yml

[ ] Step 1: Open lefthook.yml and read current state

Current content of lefthook.yml:

pre-commit:
  parallel: true
  commands:
    go-fmt:
      run: test -z "$(gofmt -l .)"
      fail_text: "Go files need formatting. Run: make format"
    go-lint:
      run: golangci-lint run
    web-lint:
      run: cd web && bun run type-check

commit-msg:
  commands:
    commitlint:
      run: cd web && bunx commitlint --config commitlint.config.ts --edit {1}

pre-push:
  commands:
    go-test:
      run: make test
      priority: 1
    web-test:
      run: make web-test
      priority: 1
    arch-test:
      run: make arch-test
      priority: 2

[ ] Step 2: Replace the commit-msg section

Replace the commit-msg block with:

commit-msg:
  commands:
    strip-ai-coauthors:
      run: perl -i -pe 's/^Co-Authored-By:.*?(claude|copilot|gemini|chatgpt|openai|cursor).*\n?//i' {1}
      priority: 1
    commitlint:
      run: cd web && bunx commitlint --config commitlint.config.ts --edit {1}
      priority: 2

[ ] Step 3: Verify the file looks correct

Run:

cat lefthook.yml

Expected output — the commit-msg section should read:

commit-msg:
  commands:
    strip-ai-coauthors:
      run: perl -i -pe 's/^Co-Authored-By:.*?(claude|copilot|gemini|chatgpt|openai|cursor).*\n?//i' {1}
      priority: 1
    commitlint:
      run: cd web && bunx commitlint --config commitlint.config.ts --edit {1}
      priority: 2

[ ] Step 4: Manually test the perl command

Create a test commit message file and run the perl command directly:

cat > /tmp/test-commit-msg.txt << 'EOF'
feat: add something

Co-Authored-By: Claude <[email protected]>
Co-Authored-By: Alice Smith <[email protected]>
Co-Authored-By: GitHub Copilot <[email protected]>
EOF

perl -i -pe 's/^Co-Authored-By:.*?(claude|copilot|gemini|chatgpt|openai|cursor).*\n?//i' /tmp/test-commit-msg.txt

cat /tmp/test-commit-msg.txt

Expected output — AI lines removed, human line kept:

feat: add something

Co-Authored-By: Alice Smith <[email protected]>

[ ] Step 5: Commit

git add lefthook.yml
git commit -m "chore: strip AI Co-Authored-By trailers in commit-msg hook"

Task 2: Reinstall hooks so lefthook picks up the change¶

Files: - No file changes — hook reinstall only

[ ] Step 1: Reinstall lefthook hooks

make hooks

Expected output: lefthook prints something like:

SYNCING
  commit-msg
  pre-commit
  pre-push

(exact output varies by lefthook version; exit code 0 is what matters)

[ ] Step 2: Verify the commit-msg hook script was updated

cat .git/hooks/commit-msg

Expected: the file should reference lefthook and exist (non-empty). Exact content depends on lefthook version.

[ ] Step 3: Do a live smoke test

Create a scratch branch, make a trivial change, commit with an AI co-author trailer, and confirm it is stripped from the recorded commit:

git checkout -b test/strip-coauthor-smoke-test
echo "// smoke test" >> lefthook.yml
git add lefthook.yml

# Write the commit message manually to a temp file to bypass interactive editor
cat > /tmp/smoke-commit.txt << 'EOF'
chore: smoke test strip-ai-coauthors hook

Co-Authored-By: Claude <[email protected]>
EOF

GIT_EDITOR="cp /tmp/smoke-commit.txt" git commit

Then inspect the recorded commit:

git log -1 --format="%B"

Expected output — no Co-Authored-By line:

chore: smoke test strip-ai-coauthors hook

[ ] Step 4: Clean up the smoke test branch

git checkout -
git branch -D test/strip-coauthor-smoke-test

[ ] Step 5: Confirm no further commits needed

No new files were created in this task. Nothing to commit.