Freeing up space · Emergency Space
What is Emergency Space in Storage Studio?
Short answer: Emergency Space is for when you're out of room: you say how much you need, it plans the smallest, safest set of steps to get there, shows you everything first, and reports what actually came back.
Emergency Space is the screen for when your Mac is genuinely out of room. You tell it how much space you need, and it puts together the smallest, safest set of steps that gets you there — then shows you everything before anything happens.
It starts with what costs you nothing: space your Mac is holding onto, then rebuildable caches and temporary files an app abandoned, then things moved to your fast drive, and only then anything deliberate. Nothing that removes data is ever ticked for you, and removals stay recoverable in the Recycle Vault.
Afterwards it tells you what actually came back. See how to open it and the manual section.