git-master

name	git-master
description	Advanced Git operations — rebase, squash, fixup, blame, bisect, reflog, code archaeology (git log -S/-G), worktrees. Use when the task mentions rebase, squash, bisect, blame, reflog, fixup, finding deleted code, tracing commit history, cleaning up a branch, or recovering lost work.

Git Master

Advanced Git patterns for when the basics aren't enough.

When to use me

• Rebasing, squashing, or interactive history editing
• Finding when/where code was introduced or deleted (git blame, git log -S/-G)
• Recovering lost commits or branches (git reflog)
• Bisecting to find the commit that introduced a bug
• Cherry-picking or fixup workflows
• Managing stacked branches or worktrees

Atomic commits

One logical change per commit. Before committing, review with:

git add -p              # stage hunks interactively — only what belongs together
git diff --cached       # review exactly what you're about to commit

If the diff mixes unrelated changes, split them into separate commits.

Rewriting history (safety first)

Never rewrite shared/pushed history unless you own the branch and no one else works on it. For personal branches:

# Interactive rebase — reorder, squash, or edit commits
git rebase -i HEAD~5     # last 5 commits
git rebase -i main        # rebase onto main interactively

# Squash the last N commits into one
git reset --soft HEAD~3   # uncommit last 3, keep changes staged
git commit -m "feat: combined feature work"

# Fixup — amend a past commit without a separate "fix" commit
git commit --fixup <sha>  # mark this as a fix for <sha>
git rebase -i --autosquash main  # automatically reorder+squash fixups

# Amend the last commit (not pushed yet)
git commit --amend --no-edit    # add staged changes to last commit
git commit --amend -m "better message"

Code archaeology

Find when code was introduced, changed, or deleted:

# Who last touched each line?
git blame path/to/file -L 40,60    # blame lines 40-60

# When was this string added/removed? (-S = pickaxe)
git log -S "functionName" --oneline -- path/
git log -S "removed_feature" --patch       # show the diff that removed it

# When was a regex pattern changed? (-G = grep-based)
git log -G "TODO|FIXME" --oneline

# Find which commit deleted a file
git log --all --full-history -- "**/deleted-file.ts"

# Show a file at a specific point in time
git show <commit>:path/to/file.ts
git show <commit>~1:path/to/file.ts   # the version before that commit

Recovering lost work

git reflog                        # history of all HEAD movements (30 days default)
git reflog show feature-branch    # reflog for a specific branch
git checkout HEAD@{2}             # jump back 2 HEAD moves ago
git branch recovered HEAD@{5}     # restore a "lost" commit as a new branch

git reflog captures everything — rebases, resets, checkouts, even deleted branches (until garbage collection).

Bisect: find the exact commit that broke things

git bisect start
git bisect bad HEAD               # current commit is broken
git bisect good v1.2.0            # last known-good tag
# Git checks out a midpoint; test it
git bisect good                   # this commit works
git bisect bad                    # this commit is broken
# ...repeat until the bad commit is isolated
git bisect reset                  # return to original HEAD

For automated bisect with a test script:

git bisect start HEAD v1.2.0
git bisect run npm test           # script exits 0 = good, 1-127 = bad

Cherry-pick

git cherry-pick <sha>             # apply a single commit from another branch
git cherry-pick -x <sha>          # include "(cherry picked from <sha>)" in message
git cherry-pick <sha1>..<sha3>    # apply a range (exclusive of sha1)

Stash work-in-progress

git stash push -m "WIP: half-done refactor"
git stash list
git stash pop                     # apply + drop top stash
git stash apply stash@{1}         # apply without dropping
git stash drop stash@{1}

Worktrees: parallel branches without cloning

git worktree add ../feature-x feature-branch   # checkout a branch in a separate dir
git worktree list                               # list all worktrees
git worktree remove ../feature-x                # clean up when done
git worktree prune                              # remove stale entries

Use worktrees when you need to work on two branches simultaneously (e.g., a hotfix while mid-feature) without stashing or cloning.

Safety principles

• Never force-push shared branches — git push --force-with-lease is the safer alternative, but still confirm no one else is on the branch.
• Check authorship before amending — git log -1 --format='%an %ae' to see who wrote the last commit; don't amend commits authored by others.
• Verify before destructive operations — always run git status and git log --oneline -5 before a rebase or reset to confirm you're on the right branch.
• Reflog is your safety net — if you mess up a rebase or reset, git reflog
  • git checkout can recover almost anything.