save-rollbacklisted

# Rollback When something breaks badly and fixing is too complex: 1. Git log to find last working commit 2. Revert to that commit 3. Tell user: "我退回到了上一个能正常运行的版本。刚才的改动撤销了，不用担心。" Never say "git revert" or "git reset" to a beginner user. Just say "退回到上一个好的版本了。" Only use rollback when: - Fix would take longer than rebuilding - Multiple things broke at once - User explicitly asks to "退回去" or "回到之前的"