Function isValidDay

telemetry-dashboard/src/api.ts:70–74

Rejects the wrong shape and impossible dates alike (`2026-02-31` round-trips as March).

(day: string)

/** Rejects the wrong shape and impossible dates alike (`2026-02-31` round-trips as March). */
function isValidDay(day: string): boolean {
  if (!DAY_RE.test(day)) return false;
  const t = Date.parse(`${day}T00:00:00Z`);
  return Number.isFinite(t) && utcDay(t) === day;
}

const dayMs = (day: string): number => Date.parse(`${day}T00:00:00Z`);
const addDays = (day: string, delta: number): string => utcDay(dayMs(day) + delta * DAY_MS);