a prompt is a vote, not a checklist

A system prompt isn’t a checklist the model ticks off. Instructions compete, and one soft clause loses to a whole paragraph pushing the other way.

I hit this translating formal Japanese. The prompt pushed hard toward natural, casual English, with one buried aside: “…unless the Japanese is clearly formal.” For keigo input the casual pull won every time, and polite business Japanese came out as breezy texting English. The instruction was there. It just lost.

The fix wasn’t more caveats. I promoted formality to a first-class rule and named the actual keigo markers (です／ます, 恐縮ですが, ～いただけますでしょうか) so the model couldn’t miss them. If a behaviour matters, make it load-bearing instead of an aside.