Are tag scores changed when a tag synonym is created?

Question

Suppose I have a score of X for tag A and a score of Y for tag B.

Now suppose that B becomes a synonym of A (A is the master).

Would my score for tags A and B change?

I can think of several options :

1. My score for tag A will become X + Y (assuming I have no upvoted answers tagged with both A and B. If such overlap does exist, my new score for tag A will be lower) and my score for B will be gone.

2. No change. Tag synonyms don't affect tag scores.

3. The score of A will become X + Y (under the same assumptions as in 1) and the score of B won't change.

The first option makes the most sense to me. Does anybody know what's the implemented logic?

Answer 1

Note that tag synonyms are not applied retroactively¹. They only affect new questions. So when B is made a synonym for A, any existing questions will still remain tagged as they are. That means your existing tag scores will be unchanged initially.

However, during mass retags, users will often retag old questions from B to A manually (moderators have tools to automate this). When this happens, your scores will change accordingly. This means more or less the same as your option 1, except that any question that was tagged with both A and B will obviously not be counted twice.

_{¹ Example: On SO, lazy is a synonym of lazy-evaluation, but there are old questions such as this one that are still tagged lazy.}