ST-321 timing with boost/barrel roll

[Genghis97]

When co-ordinating with ST-321, does the ability to acquire a lock resolve before or after the co-ordinated ship completes (or fails) its action?

For example if you co-ordinate a boost, is the range requirement for ST-321 measured from the original position of the co-ordinated ship or after it has completed (or failed) the boost?

[Dee Y]

The ST-321 lock acquisition occurs after the coordinated ship performs (or fails) the coordinated action.  That action is part of Coordinate (step 3).  ST-321 resolves after that, and you would thus measure from the post-boost position of the coordinated ship.