// Duration formatting helpers produce compact, precise, and human display

// strings from millisecond values.

export type FormatDurationSecondsOptions = {

decimals?: number;

unit?: "s" | "seconds";

// Covers duration, UTC/zoned timestamp, timezone, and relative time formatting.

import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";

import { formatUtcTimestamp, formatZonedTimestamp, resolveTimezone } from "./format-datetime.js";

import {

// Covers offsetless ISO datetime detection, timezone conversion, DST gaps, and

// sub-second round trips.

import { describe, expect, it } from "vitest";

import {

isOffsetlessIsoDateTime,

// Offsetless zoned datetime parsing interprets local wall-clock ISO strings in

// an explicit IANA time zone and rejects impossible DST times.

const OFFSETLESS_ISO_DATETIME_RE = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}(:\d{2})?(\.\d+)?$/;

const OFFSETLESS_ISO_DATETIME_PARTS_RE =

/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2})(?::(\d{2})(?:\.(\d+))?)?$/;