An interface is an example of a seam in regular code. It's basically what forms architectural shapes that you can depend on for both design and testing.

It's a fairly good concise term ... load-bearing, even. /ducks

But even then, I think "boundary" was the more common term before some LLM decided it really liked "seam" instead.

Yes, and I prefer that term because no one but claude ever talks to me using the word seam every other paragraph.

I have instructions which is confidently ignores to never use seam and instead say interface.