Implicating post_transformation → transformation
Link to implication
Reason:
To be able to tag post_transformation, the image needs enough context to determine a transformation had occurred (otherwise TWYS would dictate it not be tagged). Consequently, having an apparent transformation context should warrant the transformation tag, IMO. For the specific case of an in-progress transformation, the mid_transformation tag would be applicable.
I admit I don't quite know how this should work, given mid_transformation seems to be a rather under-utilized tag, but having transformation cover post_transformation makes sense and would be a useful for people that are looking for transformation-related content, including any aftermath.
I would also suggest the implication:
implied_transformation --> transformation
for similar reasons. There needs to be enough context to at least suggest a transformation can be or has occurred, which would generally be of interest to people searching for transformation-related content.
Updated