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Prerequisites

  • Advanced dependency types enabled (nextedy.gantt.default.advanced_dependencies=true)
  • The gantt_dependency_metadata custom field exists on your work item types (see Dependency Metadata Storage)

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How Lag Works

Each dependency link carries an optional lag value measured in days:
Lag ValueEffect
0 (default)Successor starts immediately per the dependency constraint
Positive (e.g., 2)Successor is delayed by 2 days after the constraint is met
Negative (e.g., -1)Successor can start 1 day before the constraint is met (lead time)
Lag is stored alongside the dependency type in the gantt_dependency_metadata custom field on the work item. diagram

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Step 1 — Edit the Lag Value

  1. Enter Edit mode on the Gantt chart.
  2. Double-click a dependency link arrow between two tasks to open the link editor.
  3. Set the Lag field to the desired number of days. Use a positive number for delay or a negative number for lead time.
  4. Click Save to apply the change.
The exact UI for editing lag may vary by Gantt version. If double-clicking the link arrow does not open an editor, check that your Gantt version supports lag editing.

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Step 2 — Verify Lag Persistence

After saving, reload the Gantt page. Hover over the dependency link arrow to see a tooltip displaying the link type, role name, and lag value.
Some earlier Gantt versions had an issue where lag values were not persisted correctly and would reset to 0 on page refresh. If you experience this behavior, update to the latest Gantt version and verify that the gantt_dependency_metadata custom field is properly configured.

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Step 3 — Combine Lag with Auto-Scheduling

When auto-scheduling is enabled, the Gantt takes lag into account when calculating successor start dates. A Finish-to-Start link with a lag of 3 means the successor will be scheduled to start 3 working days after the predecessor finishes.
If two tasks can partially overlap — for example, testing can begin 2 days before development finishes — set a negative lag value (e.g., -2) on the Finish-to-Start dependency link between them.

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Verification

You should now see:
  • The lag value displayed in the dependency link tooltip
  • The successor task bar shifted by the specified number of days relative to the predecessor
  • Lag values preserved after saving and reloading the Gantt chart

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See Also

KB ArticlesSupport TicketsSource Code
  • prod-gantt-src/com.nextedy.polarion.gantt.client/src/types/gantt-extended.d.ts
  • prod-gantt-src/com.nextedy.polarion.gantt/src/com/nextedy/polarion/gantt/model/Link.java
  • prod-gantt-src/com.nextedy.polarion.gantt/src/com/nextedy/polarion/gantt/model/impl/WorkItemsGanttDataService.java
  • prod-gantt-src/com.nextedy.polarion.gantt/src/com/nextedy/polarion/gantt/model/IGanttDataService.java
  • prod-gantt-src/com.nextedy.polarion.gantt/src/com/nextedy/polarion/gantt/model/IGanttService.java