Git Rebase vs Merge Explained

git checkout main
git merge feature-branch

Before:
main:    A → B → C
feature:      ↘ D → E

After merge:
main:    A → B → C → M (merge commit)
feature:      ↘ D → E ↗

git checkout feature-branch
git rebase main

Before:
main:    A → B → C
feature:      ↘ D → E

After rebase:
main:    A → B → C
feature:              → D' → E' (replayed on top of C)

git checkout main
git merge feature-branch  # Fast-forward, no merge commit

main: A → B → C → D' → E'

git rebase -i HEAD~4  # Last 4 commits

pick abc1234 Add user model
pick def5678 Fix typo in user model
pick ghi9012 Add user controller
pick jkl3456 Fix lint errors

pick abc1234 Add user model
fixup def5678 Fix typo in user model
pick ghi9012 Add user controller
fixup jkl3456 Fix lint errors

# Or via CLI
git checkout main
git merge --squash feature-branch
git commit -m "feat: add user management (#42)"

Before:
feature: D → E → F → G (4 WIP commits)

After squash merge to main:
main: A → B → C → S (one clean commit)

# On your feature branch
git fetch origin
git rebase origin/main

# Fix any conflicts
git add .
git rebase --continue

# Force push (only your branch!)
git push --force-with-lease origin feature-branch

# Option 1: Rebase (clean history)
git checkout feature-branch
git rebase main

# Option 2: Merge (preserves context)
git checkout feature-branch
git merge main

git rebase main
# CONFLICT in file.ts

# Fix the conflict
vim file.ts
git add file.ts
git rebase --continue

# Or abort and go back
git rebase --abort

- Develop on feature branches (messy commits OK)
- PR review
- Squash merge to main (one clean commit)
- Delete feature branch

- Develop on feature branches
- Interactive rebase to clean up before PR
- Fast-forward merge to main
- Delete feature branch

- Develop on feature branches
- PR review
- Merge commit to main
- Delete feature branch

# Undo last merge (before push)
git reset --hard HEAD~1

# Undo rebase
git reflog
git reset --hard HEAD@{2}  # Go back to pre-rebase state

# Cherry-pick specific commit
git cherry-pick abc1234

# Amend last commit
git commit --amend

# Autosquash (fixup commits)
git commit --fixup abc1234
git rebase -i --autosquash main