復旧のためのReflog

git reflog is a journal of every move your HEAD makes — commit, checkout, merge, rebase, reset. It's a powerful safety net for recovering lost work.

HEAD points to your current position, and the reflog records everywhere it's been. It lives locally on your machine — not in the shared repo history.

Run git reflog to see each action indexed as HEAD@{0}, HEAD@{1}, and so on — with the commit hash, the move, and a timestamp.

Read reflog output as a stack: HEAD@{0} is your current state, HEAD@{1} the one before it. Each entry marks where HEAD changed.

Accidentally ran git reset --hard HEAD~2? Don't panic — those commits aren't gone, just unreachable. The reflog still remembers where HEAD was before the reset.

Find the commit before your bad reset in git reflog, then recover it with git reset --hard <hash> — or use the index directly, like HEAD@{2}.

Deleted a branch with git branch -D? Its commits still live in your reflog, since HEAD's movements onto that branch were all recorded.

Find the deleted branch's last commit in the reflog, then recreate it: git branch my-feature <hash>. Check it out and you're back in business.

Reflog entries don't last forever: reachable ones expire after 90 days, unreachable ones after 30. It's a safety net, not a backup — always push important work.

You accidentally ran git reset --hard HEAD~3 and lost your last three commits. You check git reflog and see:

a1b2c3d HEAD@{0}: reset: moving to HEAD~3
e4f5g6h HEAD@{1}: commit: Final bug fix
f7e8d9c HEAD@{2}: commit: Implement new feature
i7j8k9l HEAD@{3}: commit: Initial setup

Which command would restore your repository to the state before the reset, bringing back "Final bug fix" and "Implement new feature"?

Recap: git reflog logs everywhere HEAD has been, your first defense against bad resets and lost branches. Recover with git reset --hard HEAD@{n} — but it does expire.