Code looks good, but it looks like this fix shows for any incorrect addition, like number + HTMLElement, and then proceeds to do nothing when invoked. Did you think about making specific errors for + et al when one of the sides is a Promise? That would make the codefix suggestion quite a bit more accurate. What do you think?

Hum, yes, I did think about it, but it should be handled by isMissingAwaitError. Something is amiss. (Related, I had a discussion with Wes in Teams about how VS Code doesn’t request code fixes for related info error codes, which would make this much cleaner. I’m thinking about PRing them to suggest a change there.)

but it looks like this fix shows for any incorrect addition, like number + HTMLElement

Ah, I thought you were saying you observed this happening, but I think you were just looking at the error codes? I believe it’s working correctly, but I just pushed a test for that negative case specifically. It’s a good thing to assert in the tests.

I gave some more context about what’s happening and why I took this approach in the inline comments, but TL;DR, the error codes are necessary but not sufficient to surface a quick fix. Once getCodeActions is invoked with a possible candidate, it correlates the error with the related message Did you forget to use 'await'? that the checker added via semantic knowledge that there’s a strong chance await is appropriate (#32239). If it doesn’t find that, it bails, and a code fix doesn’t show.

Nope, I didn't run it, just read the code. I think I was thinking of the refactor API instead of the codefix API? IIRC the refactor API is the one with two calls, and the first one has to be fast because it runs a lot.