Git interactive rebase for clean history

Feature branch has messy commits (WIP, fixup, typo fixes) that need to be cleaned before merging.

Clean up commits with interactive rebase:

# Rebase last N commits
git rebase -i HEAD~5

# Rebase from branch point
git rebase -i main

# Editor opens with commit list:
# pick abc1234 Add user model
# pick def5678 WIP
# pick ghi9012 Fix typo
# pick jkl3456 Add user API endpoint
# pick mno7890 Fix tests

# Change to:
# pick abc1234 Add user model
# squash def5678 WIP           <- merge into previous
# fixup ghi9012 Fix typo       <- merge, discard message
# pick jkl3456 Add user API endpoint
# squash mno7890 Fix tests     <- merge into previous

# Commands:
# pick   = keep commit as-is
# squash = merge into previous, combine messages
# fixup  = merge into previous, discard this message
# reword = keep commit, edit message
# edit   = pause to amend commit
# drop   = remove commit entirely

Safe workflow:

# 1. Create backup branch
git branch backup-feature

# 2. Rebase
git rebase -i main

# 3. If something goes wrong
git rebase --abort
# Or restore from backup
git reset --hard backup-feature

# 4. Auto-squash fixup commits
git commit --fixup=abc1234    # Creates: fixup! Add user model
git rebase -i --autosquash main  # Automatically reorders

Clean commit history makes code review easier, git bisect more useful, and the project history more navigable.

Cleaning up feature branch commits before merge/PR