How to Make a Custom Field Read-Only in Strategic Planning Workspace Planning Grid?

[Brijmohan]

Hi Community,

I have a requirement in ServiceNow Strategic Planning Workspace (Portfolio Planning → Planning tab).

We have a custom field named Project Number displayed as a column in the Planning grid. We want this field to be read-only for users, so they can view the value but should not be able to modify it through inline editing.

I have already tried configuring the field as read-only through the System Dictionary, but it is still editable in the Planning grid.

Could someone please suggest the recommended approach to achieve this requirement?

* Is there any OOTB configuration to make a specific column read-only in the Planning grid?
* Can this be achieved using ACLs, UI Policies, or any workspace-specific configuration?

Any guidance or a working approach would be greatly appreciated.

Thanks!