The d4-rich Prompt Pattern#

Non-reasoning chat models (deepseek-V4-Flash, grok-4.3, kimi with thinking disabled) collapse on multi-file refactor tasks when given thin or baseline prompts. Pass rates of 0-33% on canaries that reasoning models clear at 67-100%. The cheap fix is a three-part prompt addendum: completion checklist, callsites-exhaustively-updated rule, and verify-before-push instruction. Drop it into the system prompt of a non-reasoning model and the canaries go green. Drop it into a reasoning model and you pay 12× more for 0% quality improvement.