Why interrupting does not cancel a turn
Interrupting while a turn is actively running does not cancel it. The turn keeps going in the background exactly as it would have otherwise; only the local prompt stops actively waiting on it.
This gives you control of the terminal back immediately rather than being blocked until the turn finishes entirely on its own, which is useful if you want to glance at something else without losing your place.
This behavior is intentional rather than a limitation: a turn already partway through an approved file write is not something that should be cut off mid-write. See Troubleshooting if a turn appears to be genuinely stuck rather than merely taking a while.
A pending permission prompt is the one exception worth knowing: since the turn is genuinely waiting on your answer rather than doing anything, there is nothing running in the background to let continue in that specific case; getting control back simply means you can go answer it when ready.
Once you do come back to a turn that kept running, whatever it produced is already there waiting, exactly as if you had stayed and watched the whole thing happen in real time.