Undoing things safely

Pick the undo that matches where the mistake is · 7 min

In one breath

The right undo depends on how far the change got (the four places). Before pushing, you can rewrite freely. After pushing, don't rewrite. Add a new commit that reverses it (revert). And almost nothing committed is ever truly lost: reflog remembers.

Match the undo to the place

Mistake is in…	Undo	Effect
Working tree (unsaved-to-git edit)	`git restore File.cpp`	Throws the edit away. Can't be undone, so be sure
Staging (added by mistake)	`git restore --staged File.cpp`	Unstages it; your edit stays in the file
Last commit, not pushed	`git commit --amend`	Fix the message or add forgotten files to it
Recent commits, not pushed	`git reset HEAD~1`	Un-commits, keeping the changes in your files
A commit that's already pushed	`git revert abc1234`	Makes a new commit that does the opposite. History stays intact. The team-safe one.

revert vs reset: the one that matters in a team

reset moves your branch label backwards, erasing commits from history. If teammates already pulled them, your histories no longer match, and pushing needs --force (never on shared branches).
revert moves forward: a new commit that undoes the old one. Everyone just pulls it. Nothing is rewritten.

Rule: pushed means revert. Only yours and unpushed means amend or reset are fine.

The dangerous one

git reset --hard resets the branch and wipes uncommitted changes in your files. Committed work is recoverable (see below); uncommitted work is not. Run git status first, or git stash to keep things safe.

The safety net: reflog

git reflog
7a3d5fc HEAD@{0}: reset: moving to HEAD~2
9f12ab3 HEAD@{1}: commit: Add unequip axe ability      ← "lost" commit, still here
...
git switch -c rescue 9f12ab3                            # get it back on a branch

The reflog records every place HEAD has been, locally, for about 90 days. A bad reset or a deleted branch is almost always recoverable from it.

Quiz yourself

You staged a file by mistake. Undo without losing the edit?

git restore --staged File.

Typo in your last commit message, not pushed yet. Fix?

git commit --amend.

A commit that broke the build is already on GitHub's main. Undo how?

git revert <hash>: a new commit reversing it. Push that. Don't reset shared history.

revert vs reset, in one line each?

Revert adds a new opposite commit (safe after pushing). Reset moves the branch back, erasing commits (only for unpushed work).

What can git reset --hard destroy permanently?

Uncommitted changes in your working tree. Committed work can still be recovered via the reflog.

You reset away a commit and regret it. Where do you find it?

git reflog. Then branch or reset back to its hash.