>>96425042
>Much appreciated, anon, that helps a lot!
Your satisfaction is our best reward.

>But generally there is no real way to open an one-way door from the other side once it has closed?
I don't believe this is actually discussed explicitly anywhere, but it's "common knowledge" that they're undetectable and unopenable from the opposite side.

Contrast this with one-way secret passages, that are more ambiguous: Often they mean that the passage is secret on one side but unhidden on the other.