# \[Scheduling Gantt Chart\] - Chart does not always reconcile snapped date values after save-handler Action

**URL:** <https://community.palantir.com/t/scheduling-gantt-chart-chart-does-not-always-reconcile-snapped-date-values-after-save-handler-action/7173>\
**Category:** Ask the Community\
**Tags:** dynamic-scheduling, scheduler\
**Created:** [September 2, 2026, 4:46pm UTC](https://community.palantir.com/t/scheduling-gantt-chart-chart-does-not-always-reconcile-snapped-date-values-after-save-handler-action/7173 "2026-09-02T16:46:47Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ryanmoles](https://avatars.discourse-cdn.com/v4/letter/r/b77776/32.png) [@ryanmoles](https://community.palantir.com/u/ryanmoles)\
**Post date:** [September 2, 2026, 4:46pm UTC](https://community.palantir.com/t/scheduling-gantt-chart-chart-does-not-always-reconcile-snapped-date-values-after-save-handler-action/7173/1 "2026-09-02T16:46:47Z")

</div>

Good afternoon all,

I’m seeing some unexpected behaviour from a custom save handler used when resizing pucks in the Workshop Scheduling Gantt.

### **Setup**

- Background pucks represent **Team Slots**.
- Standard pucks represent **Staffings** within those Team Slots.
- Both use Ontology LocalDate start and end properties.

The save handler checks whether a user has dragged a Staffing outside its Team Slot’s date range. If so, the submitted date is snapped back to the relevant Team Slot boundary. This works correctly, and the resulting Ontology values are as expected.

### **Issue**

The problem occurs when a Staffing already sits on a Team Slot boundary and the user attempts to resize it farther beyond that boundary.

The save handler correctly snaps the submitted date back to its existing value. However, because the final value is identical to the value already stored in the Ontology, there is no material property edit for the Gantt to reconcile against.

As a result:

- The Ontology continues to contain the correct date.
- The Gantt retains the user’s optimistic dragged position.
- The puck therefore appears outside the Team Slot until the page is manually reloaded.

I have enabled auto-refresh for the Staffing and Team Slot objects in Workshop and configured the Gantt’s post-submission behaviour to reset the relevant object-set variables, but it stays in the stale rendered position.

Is there a supported way to make the Gantt roll back or reconcile its optimistic puck position after the save handler completes successfully when the final Ontology value has not materially changed?

Ideally, I would like to handle this without throwing a UserFacingError, as that treats the expected snapping behaviour as a failed Action.

Thanks!