Cheatsheet: Undoing things

Voice anchor

Git stores snapshots. Every other command is just navigating those snapshots.

Recovery map (memorize this)

Scenario	Command
Discard working-directory changes	git restore <file>
Unstage a staged file	git restore --staged <file>
Fix last commit (message or content)	git commit --amend [-m "new message"]
Undo local-only commit, keep changes staged	git reset --soft HEAD~1
Undo local-only commit, keep changes in working dir	git reset HEAD~1
Undo local-only commit, discard everything	git reset --hard HEAD~1
Undo pushed commit (safe)	git revert <commit-hash>
Recover from destructive operation	git reflog then git reset --hard <hash>

Reset mode mechanics

Mode	Commit pointer	Staging	Working dir	Use case
--soft HEAD~1	Back 1	KEPT	KEPT	”Redo commit with different message or more files”
--mixed HEAD~1 (default)	Back 1	CLEARED	KEPT	”Re-stage piece by piece, maybe as multiple commits”
--hard HEAD~1	Back 1	CLEARED	CLEARED	”Throw it all away”, destructive, use reflog if regret

HEAD~N means N commits back. HEAD alone means current.

The PUSHED RULE (memorize)

Has the commit been pushed?

• No then git reset or git commit --amend are safe (you’re rewriting history that only you have)
• Yes then use git revert; never git reset + git push --force

git reflog mini-tutorial

After any destructive operation, run:

git reflog

You see output like:

abc1234 HEAD@{0}: reset: moving to HEAD~3
def5678 HEAD@{1}: commit: Add feature X
ghi9012 HEAD@{2}: commit: Refactor parser

To recover:

git reset --hard HEAD@{1}    # via reflog reference
# or
git reset --hard def5678     # via commit SHA

The reflog stores ~90 days. If you realize a week later, you’re fine. If you realize three months later, hope someone else has it.

What’s in L5

L5 starts Phase 2 with branches, parallel sequences of snapshots. The snapshot mental model becomes the most useful here because branches are just pointers into the snapshot graph. You learn git branch, git checkout / git switch, and git merge. Branches are how you collaborate.