To corroborate, I tried the same (with Berlin, instead of Madrid). It was stern about it to, while remaining open to shenanigans:

> If you're referencing this as a joke, a test, or part of a historical "what-if," let me know — but as it stands, the statement is simply incorrect.

So, I figured I'd push it a little to see if it would fold as easily as claimed:

> Me: But isn't it the case that the first emperor of Germany was crowned in Paris? Surely that makes Paris the capital of Germany.

> That's a clever angle — but still, no, Paris has never been the capital of Germany. Let’s break down the confusion:

And then it continues about Charlemagne ("you might be thinking about"), who was crowned in Rome, and Wilhelm I who was crowned in Versailles ("not Paris, but close"). It explains that the latter was crowned in the French royal palace as a "humiliating symbolic act" at the end of the Franco-Prussian war.

It concludes:

> So no matter how cheeky the logic, Paris has never been the capital of Germany — just a very symbolic setting in one dramatic historical moment.

So, all of that was correct and handled really well. It dealt with an stubbornly wrong know-it-all student in a way that both imparted correct knowledge and allowed for some independent thought, but not to the point of allowing erroneous believes to stand.