6. Rebasing

Rebase replays your commits on top of another branch. Result: linear history.

# Basic rebase
git switch feature/login
git rebase main              # replay feature commits on top of main

# After rebase, go back to main and fast-forward merge
git switch main
git merge feature/login      # fast-forward, no merge commit

Interactive rebase (clean up history)

git rebase -i HEAD~4         # edit last 4 commits

Editor opens with a list of commits. Change the action keyword:

Action	Effect
pick	keep as-is
reword	change commit message
edit	pause to amend
squash	meld into previous commit, combine messages
fixup	meld, discard this commit's message
drop	delete this commit entirely

Example: squash 3 WIP commits into one before merge

pick a1b2c3 feat: scaffold login form
squash d4e5f6 wip: add validation
squash g7h8i9 fix: edge case null email

Result: one clean commit with a combined message.

Golden rule

Never rebase commits that have been pushed to a shared branch.
Rebase rewrites history. If others have pulled those commits, everyone's history diverges.

Safe rebase uses:

• Local-only branches
• Your own remote branch (before others pull it)
• Feature branches not yet merged

---