Function formatTimeTickValue

src/core/createRenderCoordinator.ts:1054–1090

(timestampMs: number, visibleRangeMs: number)

];

const formatTimeTickValue = (timestampMs: number, visibleRangeMs: number): string | null => {
  if (!Number.isFinite(timestampMs)) return null;
  if (!Number.isFinite(visibleRangeMs) || visibleRangeMs < 0) visibleRangeMs = 0;

  const d = new Date(timestampMs);
  // Guard against out-of-range timestamps that produce an invalid Date.
  if (!Number.isFinite(d.getTime())) return null;
  const yyyy = d.getFullYear();
  const mm = d.getMonth() + 1; // 1-12
  const dd = d.getDate();
  const hh = d.getHours();
  const min = d.getMinutes();

  // Requirements (range in ms):
  // - < 1 day: HH:mm
  // - 1-7 days: MM/DD HH:mm
  // - 1-12 weeks (and up to ~3 months): MM/DD
  // - 3-12 months: MMM DD
  // - > 1 year: YYYY/MM
  if (visibleRangeMs < MS_PER_DAY) {
    return `${pad2(hh)}:${pad2(min)}`;
  }
  // Treat the 7-day boundary as inclusive for the “1–7 days” tier.
  if (visibleRangeMs <= 7 * MS_PER_DAY) {
    return `${pad2(mm)}/${pad2(dd)} ${pad2(hh)}:${pad2(min)}`;
  }
  // Keep short calendar dates until the visible range reaches ~3 months.
  // (This covers the 1–12 week requirement, plus the small 12w→3m gap.)
  if (visibleRangeMs < 3 * MS_PER_MONTH_APPROX) {
    return `${pad2(mm)}/${pad2(dd)}`;
  }
  if (visibleRangeMs <= MS_PER_YEAR_APPROX) {
    const mmm = MONTH_SHORT_EN[d.getMonth()] ?? pad2(mm);
    return `${mmm} ${pad2(dd)}`;
  }
  return `${yyyy}/${pad2(mm)}`;
};

const generateLinearTicks = (domainMin: number, domainMax: number, tickCount: number): number[] => {
  const count = Math.max(1, Math.floor(tickCount));