Part VIII — The whole story

Put together: you ask for a locked room → the system checks whether this building has a lock and hands you one (or honestly says it can't) → you fit the lock to the door → now the worker is kept to its own bench — and, if you asked for the curtained room, out of the secret folders too, while the Linux doorkeeper also cuts the phone line by default → the locks wear a tamper-evident seal → and every promise comes with its honest limit.

If you want it, there's one optional extra on top: only the foreman holds the pen, and a clerk in the back office does the actual changing — which relies on the locked room being fitted, and trusts the owner's own computer.

The four things to carry away, one more time:

1. By default the room is unlocked — you have to ask.
2. A lock does nothing until someone turns the key.
3. The lock is proven on Linux; on Macs it's advice; on Windows there's none.
4. It contains a careless worker; it doesn't stop someone with the master key.

That's the whole of it. For the machinery behind the story, the Reference edition has every detail.