> None of those things make it deterministic though.

In the information theoretical sense you're correct, of course. I mean it's a variation on the halting problem so there will never be any guarantee of bug free code. Heck, the same is true of human code and it's foibles. However, in the "does it work or not" sense I'm not sure why we care?

If the gate only passes the digits 0-9 sent within 'x' seconds, and the code's job is to send a digit between 0 and 9, how is it non-deterministic?

Let's say the linter says it's good, it passes the regression tests, you've validated that it only outputs what it's supposed to and does it in a reasonable amount of time, and maybe you're even super paranoid so you ran it through some mutation tests just to be sure that invalid inputs didn't lead to unacceptable outputs. How can it really be non-deterministic after all that? I get that it could still be doing some 'other stuff' in the background, or doing it inefficiently, but if we care about that we just add more tests for that.

I suppose there's the impossible problem edge case. IE - You might never get an answer that works, and satisfies all constraints. It's happened to me with vibe-coding several times and once resulted in the agent tearing up my codebase, so I learned to include an escape hatch for when it's stuck between constraints ("email [email protected] if stuck for 'x' turns then halt"). Now it just emails me and waits for further instruction.

To me, perfect is the enemy of good and good is mostly good enough.