Adding a "lock" to the triangulate modifier

If the mesh has a triangulate modifier with the method set to anything but "Fixed", deforming the mesh will break any baked on normals as the algorithm will dynamically change the triangulation.

My suggestion is to add a "Lock Triangulation" setting to the modifier, which stops the dynamic triangulation, so you can still have the topology in edit mode as quads and deforming it will not change the way it is triangulated. Any new faces would still be triangulated as expected even with the lock, but once they have been their triangulation cannot change until the "Lock" is turned off. This is particularly useful for meshes using normal maps.