If it had a screen and buttons, I would try to break it.
So I started striving for highly reliable systems not because there are professional bad actors out there or spammers or to achieve high performance… but because there’s another little shit out there.
I'm not sure this is the kind of failure idempotency is design to tackle.
Idempotency tackles the issue of handling multiple requests for doing the same thing, isn't it?
yeah... there should be no extra side effect if you call something more than once on it with the same parameters. ie foo(x) is the same as foo(foo(x)) is the same as foo(foo(foo(x)))
or in networking GET x is the same as GET x followed by a GET x etc... the GET request doesn't (*shouldn't) change anything.
If you start with State A and a call changes it to State B, what does running the call again do? A->B? But you’re already at B. Shit’s going to break. Redesign your system.
If there's a process with two steps, moving from Step A to B requires the process to be at Step A and it's already at step B, it should return an error. At first glance, this doesn't seem the kind of problem that idempotency is supposed to prevent...