How to fire validation script during worklog creation?

[Chris Hotz]

We utilize Tempo Worklogs for time tracking.  We are currently experiencing an issue in which users are allowed to enter more time than is left in the remaining hours field.  We have the remaining hours optional turned off  (unchecked) and expected Tempo/JIRA to enforce that, however, users can leave remaining hours at 0 and still enter time.  

I'm looking for a workaround, such as a script that can validate and stop the worklog save if the Hours Worked on the work log plus the total hours spent on the issue is greater than the original estimate.  Due project specifics the original estimate is actually a hard cap.

I'm currently in communication with Tempo regarding what appears to be a missing enforcement on remaining time but am hoping to find a workaround in the meantime.  I appreciate any helpful thoughts you may have. Thanks!

UPDATE (Mar 6, 2019): Tempo has created a defect for their dev team to review.