Git Advanced Workflows: Rebase, Cherry-Pick, Bisect, Hooks & Team Branching Strategies

# Interactively rebase the last 5 commits
git rebase -i HEAD~5

pick 3a7f9e1 Add user authentication
pick 8b2c4d5 Fix typo in auth service
pick 1e9f2a3 WIP: working on password reset
pick 5c8d7b6 WIP still not working
pick 7a4e3f9 Password reset finally works

# Commands:
# p, pick   = use commit
# r, reword = use commit, but edit the message
# e, edit   = use commit, but stop for amending
# s, squash = melt into previous commit
# f, fixup  = squash but discard this commit's message
# d, drop   = remove commit

pick 3a7f9e1 Add user authentication
f    8b2c4d5 Fix typo in auth service     ← squash into above
r    1e9f2a3 Add password reset feature    ← reword message
f    5c8d7b6 WIP still not working         ← squash into above
f    7a4e3f9 Password reset finally works  ← squash into above

# Situation: Critical bugfix is on feature branch, needs to go to main immediately
git log --oneline feature/user-auth
# a1b2c3d Fix null pointer in AuthService  ← this specific commit
# e4f5g6h Implement OAuth2 flow
# h7i8j9k Add JWT refresh logic

# Apply just the bugfix to main
git checkout main
git cherry-pick a1b2c3d

# Cherry-pick a range of commits
git cherry-pick a1b2c3d..e4f5g6h

# Cherry-pick without committing (stage only)
git cherry-pick --no-commit a1b2c3d

# Start bisecting
git bisect start

# Current state is broken
git bisect bad

# This commit 3 weeks ago definitely worked
git bisect good v2.1.0

# Git checks out commit halfway between bad and good
# Test your application...
# If broken:
git bisect bad
# If working:
git bisect good

# Repeat ~9 times. Git tells you:
# "3a7f9e1 is the first bad commit"

# Automate with a script!
git bisect start HEAD v2.1.0
git bisect run npm test -- --testPathPattern="auth"
# Git runs your tests automatically on each commit — fully automated bisect

# .git/hooks/pre-commit (runs before every commit)
#!/bin/bash
echo "Running pre-commit checks..."

# Run TypeScript type check
npx tsc --noEmit
if [ $? -ne 0 ]; then
  echo "❌ TypeScript errors found. Fix them before committing."
  exit 1
fi

# Run linter
npx eslint --max-warnings=0 src/
if [ $? -ne 0 ]; then
  echo "❌ ESLint errors found. Fix them before committing."
  exit 1
fi

echo "✅ Pre-commit checks passed."

npm install --save-dev husky lint-staged
npx husky init

# .husky/pre-commit
npx lint-staged

# package.json
{
  "lint-staged": {
    "*.{ts,tsx}": ["eslint --fix", "prettier --write"],
    "*.{json,md}": ["prettier --write"]
  }
}

main (always deployable)
  ├── feature/add-search
  ├── fix/login-redirect
  └── chore/upgrade-dependencies

main (production)
  └── develop (integration)
        ├── feature/oauth
        ├── release/v2.3.0  ← Stabilization branch
        └── hotfix/v2.2.1   ← Emergency production fixes

# Format: <type>(<scope>): <description>
git commit -m "feat(auth): add Google OAuth2 login"
git commit -m "fix(api): handle null user in authentication middleware"
git commit -m "perf(db): add index on posts.published_at"
git commit -m "docs(readme): update local development setup"
git commit -m "refactor(users): extract UserService from AuthModule"
git commit -m "BREAKING CHANGE: rename /api/v1 to /api/v2"

# See what changed in the last commit
git show --stat

# Find which commit introduced a specific line
git log -S "functionName" --all

# Undo last commit but keep changes staged
git reset --soft HEAD~1

# Stash with a descriptive name
git stash push -m "wip: halfway through auth refactor"
git stash list
git stash pop stash@{0}

# Clean untracked files (dry-run first!)
git clean -n    # Show what would be deleted
git clean -fd   # Actually delete

# See all branches and their last commit
git branch -vv

# Revert a specific commit (safe for shared branches)
git revert 3a7f9e1 --no-edit