The Core Idea
Imagine a project with three tasks connected in sequence: Design, Build, and Test. If Design slips by two days, Build must also start two days later, which pushes Test by the same amount. Without auto-scheduling, you would need to manually adjust each task. With auto-scheduling enabled, moving Design automatically shifts Build and Test to maintain the dependency constraints.
Auto-scheduling updates the start date of a successor task according to the end date of its predecessor each time a change occurs. This allows you to maintain the project schedule by specifying relationships between tasks with no need to set dates manually.
When Design is moved to Jan 3 - Jan 7, auto-scheduling adjusts:
- Build shifts to Jan 8 - Jan 14
- Test shifts to Jan 15 - Jan 19
How It Works
Auto-scheduling is triggered only when you change a task or modify a dependency link. It does not continuously run in the background. When you drag a task bar, resize it, or edit dates in the lightbox, the Gantt evaluates all downstream dependencies and adjusts successor dates to satisfy the constraints.
The propagation follows dependency link types:
| Dependency type | Constraint |
|---|
| Finish-to-Start (FS) | Successor starts after predecessor finishes |
| Start-to-Start (SS) | Successor starts when predecessor starts |
| Finish-to-Finish (FF) | Successor finishes when predecessor finishes |
| Start-to-Finish (SF) | Successor finishes when predecessor starts |
When auto-scheduling is disabled and a successor’s start date is planned before the predecessor finishes, the Gantt highlights the conflict visually. This helps you spot scheduling violations even in manual scheduling mode.
Enabling and Controlling Auto-Scheduling
Auto-scheduling is controlled at the server level via the administration property nextedy.gantt.default.auto_scheduling. When set to true, the Gantt opens with auto-scheduling enabled by default.
Users can toggle auto-scheduling on and off at runtime using the toolbar toggle button. This allows switching between automatic constraint enforcement and manual date editing within the same session.
Per-Task Overrides
In complex projects, you may want auto-scheduling for most tasks but need certain tasks (such as milestones or fixed-date deliverables) to remain pinned. The Gantt supports per-task override flags:
enforceAutoMode — Forces auto-scheduling for a specific task, even if the global setting is offblockAutoMode — Prevents auto-scheduling from moving a specific task, even if the global setting is on
These flags enable mixed scheduling strategies where top-level milestones remain fixed while lower-level tasks are automatically adjusted.
When combining auto-scheduling with parent-child hierarchies, the behavior can become complex. Moving a parent task propagates to children, which in turn may trigger dependency propagation on their successors. If you need to prevent auto-scheduling on top-level work items while allowing it on lower levels, consider using a combination of readonly mode for top-level items and per-task blockAutoMode flags.
Interaction with Drag Children
The dragChildren configuration controls whether child tasks move together with their parent when the parent is dragged. When both dragChildren and auto-scheduling are enabled:
- Dragging the parent moves all children by the same offset
- Auto-scheduling then recalculates any successors of those children
This two-step behavior means that moving a parent task can cascade changes throughout the project schedule.
Interaction with Working Calendars
When working calendars are enabled, auto-scheduling respects non-working days. If a predecessor finishes on Friday and the successor has a Finish-to-Start dependency, the successor will start on Monday (skipping the weekend) rather than Saturday. This applies to all calendar exceptions including holidays and per-user off days.
What Auto-Scheduling Does Not Do
Auto-scheduling operates on the client side during the current editing session. It does not:
- Run automatically when Polarion data changes outside the Gantt (e.g., another user modifies dates via the Polarion work item form)
- Detect concurrent editing conflicts — the last save wins
- Automatically resolve resource overallocation
Auto-scheduling recalculates dates based on dependency constraints only. For resource capacity analysis, see Resource Load Calculation Modes.
