I’m happy to announce that we’ve just released the workflow validator module for Connect apps, which joins the workflow condition module that was introduced a few months ago.
See the documentation for more details:
To declare a condition or validator, the app needs to provide a Jira expression that will control its behvaiour. Jira expressions are a domain-specific language evaluated on the Jira side, which makes it possible for conditions and validators to be executed synchronously, without any remote calls.
Keep in mind that after a Connect app adds a validator or condition, it still needs to be added to a transition by Jira admins, just like any other (built-in) condition or validator. They are not applied automatically to all transitions.
Looking forward to hearing your feedback and seeing all the amazing things you will be able to build with this!