/** * Shapes merged daily totals into the per-day provider stacks both chart * implementations (Swift Charts on iOS, plain views elsewhere) render. * * @module usageChartData */import type { UsageProviderKind } from "@t3tools/contracts";import type { DailyTotals } from "@t3tools/shared/usageMerge"; import { PROVIDER_ORDER } from "./usageProviders"; export type UsageChartMetric = "cost" | "tokens"; export interface UsageChartDay {  readonly day: string;  /** In {@link PROVIDER_ORDER}, i.e. bottom of the stack first. */  readonly values: readonly { readonly provider: UsageProviderKind; readonly value: number }[];  readonly total: number;} /** One entry per day in the window, zero-filled where nothing happened. */export function buildChartDays(  days: readonly string[],  daily: readonly DailyTotals[],  metric: UsageChartMetric,): readonly UsageChartDay[] {  const byDay = new Map(daily.map((totals) => [totals.day, totals]));  return days.map((day) => {    const totals = byDay.get(day);    const values = PROVIDER_ORDER.map((provider) => {      const entry = totals?.byProvider.get(provider);      const value = entry === undefined ? 0 : metric === "cost" ? entry.costUsd : entry.totalTokens;      return { provider, value };    });    return {      day,      values,      total: values.reduce((sum, entry) => sum + entry.value, 0),    };  });}