Price case notes for flagged card payments

Most payments never touch a model. The few that do decide the bill, and one number decides it most.

Your task

Declare the fraud review pipeline, price it per month, and find where the bill is most sensitive.

• declare PIPELINE: one entry per step, with an eval and a fallback on every model step
• write monthly_cost(pipeline, prices, items_per_day, days) and get the arithmetic right
• prices are dollars per million tokens; the cache discount applies to INPUT tokens only
• a step with no cached_in_frac has nothing cached; a step with no cache_discount pays the full rate on cached input
• runs_per_item is fan-out and retries together: 0.4 percent of payments, generated twice, is 0.008
• round to cents once, on the monthly total

design.md and cost_math.md are read by the critique, not by the suite. Say in them where the bill is most sensitive.