import type { UsageModelPriceOverride } from "@t3tools/contracts"; export const USAGE_PRICE_FIELDS = [  { key: "inputCostPerMillionTokens", label: "Input", optional: false },  { key: "outputCostPerMillionTokens", label: "Output", optional: false },  { key: "cacheReadCostPerMillionTokens", label: "Cache read", optional: true },  { key: "cacheWriteCostPerMillionTokens", label: "Cache write", optional: true },] as const; export type UsagePriceForm = { model: string } & Record<  (typeof USAGE_PRICE_FIELDS)[number]["key"],  string>; export function usagePriceForm(model = "", price?: UsageModelPriceOverride): UsagePriceForm {  return {    model,    inputCostPerMillionTokens: price?.inputCostPerMillionTokens.toString() ?? "",    outputCostPerMillionTokens: price?.outputCostPerMillionTokens.toString() ?? "",    cacheReadCostPerMillionTokens: price?.cacheReadCostPerMillionTokens?.toString() ?? "",    cacheWriteCostPerMillionTokens: price?.cacheWriteCostPerMillionTokens?.toString() ?? "",  };} /** Blank cache prices use the input rate; explicit zero means free. */export function parseUsagePriceForm(  form: UsagePriceForm,): { model: string; price: UsageModelPriceOverride } | null {  const model = form.model.trim();  if (model.length === 0) return null;  const rates: Partial<Record<(typeof USAGE_PRICE_FIELDS)[number]["key"], number>> = {};  for (const field of USAGE_PRICE_FIELDS) {    const raw = form[field.key].trim();    if (raw === "") {      if (field.optional) continue;      return null;    }    if (!/^(?:\d+(?:\.\d*)?|\.\d+)(?:e[+-]?\d+)?$/i.test(raw)) return null;    const value = Number(raw);    if (!Number.isFinite(value) || value < 0) return null;    rates[field.key] = value;  }  if (    rates.inputCostPerMillionTokens === undefined ||    rates.outputCostPerMillionTokens === undefined  ) {    return null;  }  return {    model,    price: {      inputCostPerMillionTokens: rates.inputCostPerMillionTokens,      outputCostPerMillionTokens: rates.outputCostPerMillionTokens,      ...(rates.cacheReadCostPerMillionTokens === undefined        ? {}        : { cacheReadCostPerMillionTokens: rates.cacheReadCostPerMillionTokens }),      ...(rates.cacheWriteCostPerMillionTokens === undefined        ? {}        : { cacheWriteCostPerMillionTokens: rates.cacheWriteCostPerMillionTokens }),    },  };}