Engine Logic

Source code

Astro astro

---
import GanttScheduling from '@revolist/revogrid-examples/components/gantt/GanttScheduling.vue';
---

<GanttScheduling client:only="vue" />

TypeScript ts

// src/components/gantt/GanttScheduling.ts
import { defineCustomElements } from '@revolist/revogrid/loader';
defineCustomElements();

import { GanttPlugin, createDefaultTaskTableColumn } from '@revolist/revogrid-enterprise';
import type { TaskEntity, DependencyEntity, CalendarEntity } from '@revolist/revogrid-enterprise';
import { currentTheme } from '../composables/useRandomData';

const { isDark } = currentTheme();

const PROJECT_ID = 'project-web-redesign';
const CALENDAR_ID = 'cal-us';

// Calendar-aware scheduling: durations are in working days (Mon–Fri, excluding holidays)
const ganttConfig = {
  id: PROJECT_ID,
  name: 'Website Redesign',
  version: '1',
  currency: 'USD',
  timeZone: 'America/New_York',
  primaryCalendarId: CALENDAR_ID,
  updatedAt: '2026-04-06T00:00:00Z',
  zoomPreset: 'week' as const,
  scheduling: {
    excludeHolidaysFromDuration: true, // durations skip weekends and holidays
  },
  visuals: {
    shadeNonWorkingTime: true, // shade weekend columns on the timeline
    projectLineDate: '2026-04-06', // vertical status-date line
  },
};

// US calendar with public holidays
const calendars: CalendarEntity[] = [
  {
    id: CALENDAR_ID,
    name: 'US Standard',
    timeZone: 'America/New_York',
    workingDays: [1, 2, 3, 4, 5], // Mon–Fri
    holidays: [
      '2026-05-25', // Memorial Day
      '2026-07-04', // Independence Day
    ],
    hoursPerDay: 8,
  },
];

const tasks: TaskEntity[] = [
  {
    id: 't1', projectId: PROJECT_ID, parentId: null,
    wbsCode: '1', name: 'Design', type: 'summary', status: 'in-progress',
    startDate: '2026-04-06', endDate: '2026-04-24', durationDays: 15,
    progressPercent: 60, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't2', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.1', name: 'Wireframes', type: 'task', status: 'done',
    startDate: '2026-04-06', endDate: '2026-04-10', durationDays: 5,
    progressPercent: 100, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't3', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.2', name: 'Design Review', type: 'milestone', status: 'done',
    startDate: '2026-04-10', endDate: '2026-04-10', durationDays: 0,
    progressPercent: 100, calendarId: CALENDAR_ID, isCritical: true, tags: ['milestone'],
  },
  {
    id: 't4', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.3', name: 'Visual Design', type: 'task', status: 'in-progress',
    startDate: '2026-04-13', endDate: '2026-04-24', durationDays: 10,
    progressPercent: 40, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't5', projectId: PROJECT_ID, parentId: null,
    wbsCode: '2', name: 'Development', type: 'summary', status: 'not-started',
    startDate: '2026-04-27', endDate: '2026-05-28', durationDays: 24,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: false, tags: [],
  },
  {
    id: 't6', projectId: PROJECT_ID, parentId: 't5',
    wbsCode: '2.1', name: 'Frontend', type: 'task', status: 'not-started',
    // constraint: cannot start before May 4 (waiting on external API)
    startDate: '2026-05-04', endDate: '2026-05-20', durationDays: 13,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    constraintType: 'start-no-earlier-than',
    constraintDate: '2026-05-04',
  },
  {
    id: 't7', projectId: PROJECT_ID, parentId: 't5',
    wbsCode: '2.2', name: 'Backend', type: 'task', status: 'not-started',
    startDate: '2026-04-27', endDate: '2026-05-28', durationDays: 24,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    deadlineDate: '2026-05-22', // deadline marker — project expects early delivery
  },
  {
    id: 't8', projectId: PROJECT_ID, parentId: null,
    wbsCode: '3', name: 'Launch', type: 'milestone', status: 'not-started',
    startDate: '2026-05-28', endDate: '2026-05-28', durationDays: 0,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: ['milestone'],
  },
];

const dependencies: DependencyEntity[] = [
  { id: 'd1', predecessorTaskId: 't2', successorTaskId: 't3', type: 'finish-to-start', lagDays: 0 },
  { id: 'd2', predecessorTaskId: 't3', successorTaskId: 't4', type: 'finish-to-start', lagDays: 1 },
  { id: 'd3', predecessorTaskId: 't4', successorTaskId: 't6', type: 'finish-to-start', lagDays: 1 },
  { id: 'd4', predecessorTaskId: 't4', successorTaskId: 't7', type: 'finish-to-start', lagDays: 1 },
  { id: 'd5', predecessorTaskId: 't6', successorTaskId: 't8', type: 'finish-to-start', lagDays: 0 },
  { id: 'd6', predecessorTaskId: 't7', successorTaskId: 't8', type: 'finish-to-start', lagDays: 0 },
];

export function load(parentSelector: string) {
  const grid = document.createElement('revo-grid');

  grid.theme = isDark() ? 'darkCompact' : 'compact';
  grid.hideAttribution = true;
  grid.plugins = [GanttPlugin];
  grid.gantt = ganttConfig;
  grid.ganttCalendars = calendars;
  grid.ganttDependencies = dependencies;
  grid.source = tasks;
  grid.columns = [
    createDefaultTaskTableColumn('wbs'),
    createDefaultTaskTableColumn('name'),
  ];

  document.querySelector(parentSelector)?.appendChild(grid);
}

Vue vue

<template>
  <RevoGrid
    hide-attribution
    style="height: 500px"
    :theme="isDark ? 'darkCompact' : 'compact'"
    :plugins="plugins"
    :source="tasks"
    :columns="columns"
    :gantt.prop="ganttConfig"
    :gantt-dependencies.prop="dependencies"
    :gantt-calendars.prop="calendars"
  />
</template>

<script setup lang="ts">
import { ref } from 'vue';
import RevoGrid from '@revolist/vue3-datagrid';
import { GanttPlugin, createDefaultTaskTableColumn } from '@revolist/revogrid-enterprise';
import type { TaskEntity, DependencyEntity, CalendarEntity } from '@revolist/revogrid-enterprise';
import { currentThemeVue } from '../composables/useRandomData';

const { isDark } = currentThemeVue();

const PROJECT_ID = 'project-web-redesign';
const CALENDAR_ID = 'cal-us';

const plugins = ref([GanttPlugin]);

const ganttConfig = ref({
  id: PROJECT_ID,
  name: 'Website Redesign',
  version: '1',
  currency: 'USD',
  timeZone: 'America/New_York',
  primaryCalendarId: CALENDAR_ID,
  updatedAt: '2026-04-06T00:00:00Z',
  zoomPreset: 'week' as const,
  scheduling: {
    excludeHolidaysFromDuration: true,
  },
  visuals: {
    shadeNonWorkingTime: true,
    projectLineDate: '2026-04-06',
  },
});

const calendars = ref<CalendarEntity[]>([
  {
    id: CALENDAR_ID,
    name: 'US Standard',
    timeZone: 'America/New_York',
    workingDays: [1, 2, 3, 4, 5],
    holidays: ['2026-05-25', '2026-07-04'],
    hoursPerDay: 8,
  },
]);

const tasks = ref<TaskEntity[]>([
  {
    id: 't1', projectId: PROJECT_ID, parentId: null,
    wbsCode: '1', name: 'Design', type: 'summary', status: 'in-progress',
    startDate: '2026-04-06', endDate: '2026-04-24', durationDays: 15,
    progressPercent: 60, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't2', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.1', name: 'Wireframes', type: 'task', status: 'done',
    startDate: '2026-04-06', endDate: '2026-04-10', durationDays: 5,
    progressPercent: 100, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't3', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.2', name: 'Design Review', type: 'milestone', status: 'done',
    startDate: '2026-04-10', endDate: '2026-04-10', durationDays: 0,
    progressPercent: 100, calendarId: CALENDAR_ID, isCritical: true, tags: ['milestone'],
  },
  {
    id: 't4', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.3', name: 'Visual Design', type: 'task', status: 'in-progress',
    startDate: '2026-04-13', endDate: '2026-04-24', durationDays: 10,
    progressPercent: 40, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't5', projectId: PROJECT_ID, parentId: null,
    wbsCode: '2', name: 'Development', type: 'summary', status: 'not-started',
    startDate: '2026-04-27', endDate: '2026-05-28', durationDays: 24,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: false, tags: [],
  },
  {
    id: 't6', projectId: PROJECT_ID, parentId: 't5',
    wbsCode: '2.1', name: 'Frontend', type: 'task', status: 'not-started',
    startDate: '2026-05-04', endDate: '2026-05-20', durationDays: 13,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    constraintType: 'start-no-earlier-than',
    constraintDate: '2026-05-04',
  },
  {
    id: 't7', projectId: PROJECT_ID, parentId: 't5',
    wbsCode: '2.2', name: 'Backend', type: 'task', status: 'not-started',
    startDate: '2026-04-27', endDate: '2026-05-28', durationDays: 24,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    deadlineDate: '2026-05-22',
  },
  {
    id: 't8', projectId: PROJECT_ID, parentId: null,
    wbsCode: '3', name: 'Launch', type: 'milestone', status: 'not-started',
    startDate: '2026-05-28', endDate: '2026-05-28', durationDays: 0,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: ['milestone'],
  },
]);

const dependencies = ref<DependencyEntity[]>([
  { id: 'd1', predecessorTaskId: 't2', successorTaskId: 't3', type: 'finish-to-start', lagDays: 0 },
  { id: 'd2', predecessorTaskId: 't3', successorTaskId: 't4', type: 'finish-to-start', lagDays: 1 },
  { id: 'd3', predecessorTaskId: 't4', successorTaskId: 't6', type: 'finish-to-start', lagDays: 1 },
  { id: 'd4', predecessorTaskId: 't4', successorTaskId: 't7', type: 'finish-to-start', lagDays: 1 },
  { id: 'd5', predecessorTaskId: 't6', successorTaskId: 't8', type: 'finish-to-start', lagDays: 0 },
  { id: 'd6', predecessorTaskId: 't7', successorTaskId: 't8', type: 'finish-to-start', lagDays: 0 },
]);

const columns = ref([
  createDefaultTaskTableColumn('wbs'),
  createDefaultTaskTableColumn('name'),
]);
</script>

React tsx

import React, { useMemo } from 'react';
import { RevoGrid } from '@revolist/react-datagrid';
import { GanttPlugin, createDefaultTaskTableColumn } from '@revolist/revogrid-enterprise';
import type { TaskEntity, DependencyEntity, CalendarEntity } from '@revolist/revogrid-enterprise';
import { currentTheme } from '../composables/useRandomData';

const { isDark } = currentTheme();

const PROJECT_ID = 'project-web-redesign';
const CALENDAR_ID = 'cal-us';

const tasks: TaskEntity[] = [
  {
    id: 't1', projectId: PROJECT_ID, parentId: null,
    wbsCode: '1', name: 'Design', type: 'summary', status: 'in-progress',
    startDate: '2026-04-06', endDate: '2026-04-24', durationDays: 15,
    progressPercent: 60, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't2', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.1', name: 'Wireframes', type: 'task', status: 'done',
    startDate: '2026-04-06', endDate: '2026-04-10', durationDays: 5,
    progressPercent: 100, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't3', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.2', name: 'Design Review', type: 'milestone', status: 'done',
    startDate: '2026-04-10', endDate: '2026-04-10', durationDays: 0,
    progressPercent: 100, calendarId: CALENDAR_ID, isCritical: true, tags: ['milestone'],
  },
  {
    id: 't4', projectId: PROJECT_ID, parentId: 't1',
    wbsCode: '1.3', name: 'Visual Design', type: 'task', status: 'in-progress',
    startDate: '2026-04-13', endDate: '2026-04-24', durationDays: 10,
    progressPercent: 40, calendarId: CALENDAR_ID, isCritical: true, tags: [],
  },
  {
    id: 't5', projectId: PROJECT_ID, parentId: null,
    wbsCode: '2', name: 'Development', type: 'summary', status: 'not-started',
    startDate: '2026-04-27', endDate: '2026-05-28', durationDays: 24,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: false, tags: [],
  },
  {
    id: 't6', projectId: PROJECT_ID, parentId: 't5',
    wbsCode: '2.1', name: 'Frontend', type: 'task', status: 'not-started',
    startDate: '2026-05-04', endDate: '2026-05-20', durationDays: 13,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    constraintType: 'start-no-earlier-than',
    constraintDate: '2026-05-04',
  },
  {
    id: 't7', projectId: PROJECT_ID, parentId: 't5',
    wbsCode: '2.2', name: 'Backend', type: 'task', status: 'not-started',
    startDate: '2026-04-27', endDate: '2026-05-28', durationDays: 24,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    deadlineDate: '2026-05-22',
  },
  {
    id: 't8', projectId: PROJECT_ID, parentId: null,
    wbsCode: '3', name: 'Launch', type: 'milestone', status: 'not-started',
    startDate: '2026-05-28', endDate: '2026-05-28', durationDays: 0,
    progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: ['milestone'],
  },
];

const dependencies: DependencyEntity[] = [
  { id: 'd1', predecessorTaskId: 't2', successorTaskId: 't3', type: 'finish-to-start', lagDays: 0 },
  { id: 'd2', predecessorTaskId: 't3', successorTaskId: 't4', type: 'finish-to-start', lagDays: 1 },
  { id: 'd3', predecessorTaskId: 't4', successorTaskId: 't6', type: 'finish-to-start', lagDays: 1 },
  { id: 'd4', predecessorTaskId: 't4', successorTaskId: 't7', type: 'finish-to-start', lagDays: 1 },
  { id: 'd5', predecessorTaskId: 't6', successorTaskId: 't8', type: 'finish-to-start', lagDays: 0 },
  { id: 'd6', predecessorTaskId: 't7', successorTaskId: 't8', type: 'finish-to-start', lagDays: 0 },
];

const calendars: CalendarEntity[] = [
  {
    id: CALENDAR_ID,
    name: 'US Standard',
    timeZone: 'America/New_York',
    workingDays: [1, 2, 3, 4, 5],
    holidays: ['2026-05-25', '2026-07-04'],
    hoursPerDay: 8,
  },
];

function GanttScheduling() {
  const ganttConfig = useMemo(() => ({
    id: PROJECT_ID,
    name: 'Website Redesign',
    version: '1',
    currency: 'USD',
    timeZone: 'America/New_York',
    primaryCalendarId: CALENDAR_ID,
    updatedAt: '2026-04-06T00:00:00Z',
    zoomPreset: 'week' as const,
    scheduling: {
      excludeHolidaysFromDuration: true,
    },
    visuals: {
      shadeNonWorkingTime: true,
      projectLineDate: '2026-04-06',
    },
  }), []);

  const columns = useMemo(() => [
    createDefaultTaskTableColumn('wbs'),
    createDefaultTaskTableColumn('name'),
  ], []);

  return (
    <RevoGrid
      style={{ height: '500px' }}
      theme={isDark() ? 'darkCompact' : 'compact'}
      hideAttribution
      plugins={[GanttPlugin]}
      source={tasks}
      columns={columns}
      gantt={ganttConfig}
      ganttDependencies={dependencies}
      ganttCalendars={calendars}
    />
  );
}

export default GanttScheduling;

Angular ts

import { Component, NO_ERRORS_SCHEMA, ViewEncapsulation } from '@angular/core';
import { RevoGrid } from '@revolist/angular-datagrid';
import { GanttPlugin, createDefaultTaskTableColumn } from '@revolist/revogrid-enterprise';
import type { TaskEntity, DependencyEntity, CalendarEntity } from '@revolist/revogrid-enterprise';
import { currentTheme } from '../composables/useRandomData';

const PROJECT_ID = 'project-web-redesign';
const CALENDAR_ID = 'cal-us';

@Component({
  selector: 'gantt-scheduling-grid',
  standalone: true,
  imports: [RevoGrid],
  // Allows Angular demos to bind RevoGrid plugin props that are not wrapper inputs.
  schemas: [NO_ERRORS_SCHEMA],
  template: `
    <revo-grid
      style="min-height: 500px"
      [theme]="theme"
      [hideAttribution]="true"
      [plugins]="plugins"
      [source]="tasks"
      [columns]="columns"
      [gantt]="ganttConfig"
      [ganttDependencies]="dependencies"
      [ganttCalendars]="calendars"
    ></revo-grid>
  `,
  encapsulation: ViewEncapsulation.None,
})
export class GanttSchedulingGridComponent {
  theme = currentTheme().isDark() ? 'darkCompact' : 'compact';
  plugins = [GanttPlugin];

  ganttConfig = {
    id: PROJECT_ID,
    name: 'Website Redesign',
    version: '1',
    currency: 'USD',
    timeZone: 'America/New_York',
    primaryCalendarId: CALENDAR_ID,
    updatedAt: '2026-04-06T00:00:00Z',
    zoomPreset: 'week' as const,
    scheduling: {
      excludeHolidaysFromDuration: true,
    },
    visuals: {
      shadeNonWorkingTime: true,
      projectLineDate: '2026-04-06',
    },
  };

  calendars: CalendarEntity[] = [
    {
      id: CALENDAR_ID,
      name: 'US Standard',
      timeZone: 'America/New_York',
      workingDays: [1, 2, 3, 4, 5],
      holidays: ['2026-05-25', '2026-07-04'],
      hoursPerDay: 8,
    },
  ];

  tasks: TaskEntity[] = [
    {
      id: 't1', projectId: PROJECT_ID, parentId: null,
      wbsCode: '1', name: 'Design', type: 'summary', status: 'in-progress',
      startDate: '2026-04-06', endDate: '2026-04-24', durationDays: 15,
      progressPercent: 60, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    },
    {
      id: 't2', projectId: PROJECT_ID, parentId: 't1',
      wbsCode: '1.1', name: 'Wireframes', type: 'task', status: 'done',
      startDate: '2026-04-06', endDate: '2026-04-10', durationDays: 5,
      progressPercent: 100, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    },
    {
      id: 't3', projectId: PROJECT_ID, parentId: 't1',
      wbsCode: '1.2', name: 'Design Review', type: 'milestone', status: 'done',
      startDate: '2026-04-10', endDate: '2026-04-10', durationDays: 0,
      progressPercent: 100, calendarId: CALENDAR_ID, isCritical: true, tags: ['milestone'],
    },
    {
      id: 't4', projectId: PROJECT_ID, parentId: 't1',
      wbsCode: '1.3', name: 'Visual Design', type: 'task', status: 'in-progress',
      startDate: '2026-04-13', endDate: '2026-04-24', durationDays: 10,
      progressPercent: 40, calendarId: CALENDAR_ID, isCritical: true, tags: [],
    },
    {
      id: 't5', projectId: PROJECT_ID, parentId: null,
      wbsCode: '2', name: 'Development', type: 'summary', status: 'not-started',
      startDate: '2026-04-27', endDate: '2026-05-28', durationDays: 24,
      progressPercent: 0, calendarId: CALENDAR_ID, isCritical: false, tags: [],
    },
    {
      id: 't6', projectId: PROJECT_ID, parentId: 't5',
      wbsCode: '2.1', name: 'Frontend', type: 'task', status: 'not-started',
      startDate: '2026-05-04', endDate: '2026-05-20', durationDays: 13,
      progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: [],
      constraintType: 'start-no-earlier-than',
      constraintDate: '2026-05-04',
    },
    {
      id: 't7', projectId: PROJECT_ID, parentId: 't5',
      wbsCode: '2.2', name: 'Backend', type: 'task', status: 'not-started',
      startDate: '2026-04-27', endDate: '2026-05-28', durationDays: 24,
      progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: [],
      deadlineDate: '2026-05-22',
    },
    {
      id: 't8', projectId: PROJECT_ID, parentId: null,
      wbsCode: '3', name: 'Launch', type: 'milestone', status: 'not-started',
      startDate: '2026-05-28', endDate: '2026-05-28', durationDays: 0,
      progressPercent: 0, calendarId: CALENDAR_ID, isCritical: true, tags: ['milestone'],
    },
  ];

  dependencies: DependencyEntity[] = [
    { id: 'd1', predecessorTaskId: 't2', successorTaskId: 't3', type: 'finish-to-start', lagDays: 0 },
    { id: 'd2', predecessorTaskId: 't3', successorTaskId: 't4', type: 'finish-to-start', lagDays: 1 },
    { id: 'd3', predecessorTaskId: 't4', successorTaskId: 't6', type: 'finish-to-start', lagDays: 1 },
    { id: 'd4', predecessorTaskId: 't4', successorTaskId: 't7', type: 'finish-to-start', lagDays: 1 },
    { id: 'd5', predecessorTaskId: 't6', successorTaskId: 't8', type: 'finish-to-start', lagDays: 0 },
    { id: 'd6', predecessorTaskId: 't7', successorTaskId: 't8', type: 'finish-to-start', lagDays: 0 },
  ];

  columns = [
    createDefaultTaskTableColumn('wbs'),
    createDefaultTaskTableColumn('name'),
  ];
}

The RevoGrid Gantt scheduling engine follows a deterministic pipeline to compute effective dates for all tasks. It processes data changes in five distinct phases to ensure dependency safety and constraint satisfaction.

The 5-Step Pipeline

1. Topological Sort

The engine first builds a dependency graph and performs a topological sort. This ensures that tasks are ordered such that every predecessor is processed before its successors.

• Summary tasks are handled separately to ensure they can roll up dates from their children.
• Circular dependencies are detected and reported as errors.

2. Forward Pass (ASAP)

In the default scheduleFrom: 'project-start' mode, the engine performs a forward pass:

• Root tasks (those without predecessors) are anchored to the projectStartDate.
• Successors are shifted forward to satisfy their incoming dependencies (FS, SS, FF, SF) plus any lagDays.
• The engine uses the successor’s calendar to compute working-day offsets if lagCalendar: 'working-days' is enabled.

3. Constraint Application

Once the dependency-driven dates are known, the engine applies per-task constraints:

• Soft Constraints: SNET, SNLT, etc., refine the start date if the dependency date falls outside the constraint bound.
• Hard Constraints: must-start-on and must-finish-on override the forward pass results. If a hard constraint violates a dependency, a conflict is reported, but the constraint date wins.

4. Summary Rollup

After all leaf tasks have their dates resolved, the engine rolls up the schedule to summary (parent) tasks:

• A summary task’s startDate is the minimum of its children’s startDate.
• A summary task’s endDate is the maximum of its children’s endDate.
• Rollup is recursive, traversing the entire WBS (Work Breakdown Structure) tree.

5. Critical Path Analysis

The final phase computes the project’s early and late dates using a backward pass from the project finish date:

• Total Slack: The number of days a task can be delayed without delaying the project finish.
• Critical Path: Tasks with zero total slack are marked as isCritical.
• This analysis helps planners identify the “chain” of tasks that determines the total project duration.

Conflict Resolution

The engine prioritizes user intent and data integrity when scheduling rules collide:

Priority	Rule	Outcome
High	Actuals	actualStartDate and actualFinishDate pin the task; the engine won’t move them.
High	Hard Constraints	MSO / MFO dates win over dependencies; conflict reported.
Medium	Dependencies	Auto-tasks are clamped to satisfy predecessors.
Medium	Soft Constraints	Dates are adjusted to bounds where possible; conflict reported if windows are disjoint.
Low	Authored Dates	Used as the starting point for root tasks or manual tasks.

Tip

The scheduling engine runs synchronously on each render to provide immediate feedback during drag-and-drop or inline editing.