Working Calendar

FluxGantt schedules against a working calendar — which weekdays are working days, the hours within them, holidays, and a timezone. Durations are measured in working hours, so a task never gets "worked on" over a weekend or holiday, and all math is DST-correct because it runs through the Temporal API.

The default

If you don't pass a calendar, FluxGantt uses DEFAULT_CALENDAR:

import { DEFAULT_CALENDAR } from '@fluxgantt/core';
 
// DEFAULT_CALENDAR:
// {
//   workingDays: ['mon', 'tue', 'wed', 'thu', 'fri'],
//   workingHours: [{ start: '09:00', end: '17:00' }],
//   holidays: [],
//   timezone: 'UTC',
// }

That's Monday–Friday, 9-to-5, no holidays, UTC.

Supplying your own

import { createGantt } from '@fluxgantt/core';
import type { WorkingCalendar } from '@fluxgantt/core';
 
const calendar: WorkingCalendar = {
  workingDays: ['mon', 'tue', 'wed', 'thu', 'fri'],
  workingHours: [
    { start: '09:00', end: '12:00' }, // multiple windows model a lunch break
    { start: '13:00', end: '17:00' },
  ],
  holidays: ['2026-08-31'],           // DateInput[]
  timezone: 'America/New_York',
};
 
const gantt = createGantt({ tasks: [/* … */], calendar });

WorkingCalendar shape

The calendar is immutable for the life of the instance in v1 (there is no setCalendar()).

Calendar-aware helpers

The same functions the engine uses internally are exported for your own date math:

import {
  isWorkingDay,
  isHoliday,
  addWorkingHours,
  subtractWorkingHours,
  differenceInWorkingHours,
  normalizeDate,
  DEFAULT_CALENDAR,
} from '@fluxgantt/core';

• addWorkingHours(start, hours, calendar) / subtractWorkingHours(...) — advance a date by working hours, skipping non-working time.
• differenceInWorkingHours(start, end, calendar) — the working-hours span between two dates.
• isWorkingDay(date, calendar) / isHoliday(date, calendar) — predicates.
• normalizeDate(input, timezone) — turn a DateInput into a Temporal.ZonedDateTime.

These power resizeTask (which interprets its duration as working hours) and the critical-path computation, so a task's rendered span and its schedule always agree.