Not only is the API called `FileSavePicker.PickSaveFileAsync` which any reasonable person would assume would give you a truncated file, but even Microsoft agrees that it should give you a truncated file.
Sorry, my "reasonable" interpretation of the name tells me that it's a method to choose the file you want to save. It suggests absolutely nothing about actually writing data.
Now continue reading the rest of the sentence.
`FileSavePicker.PickSaveFileAsync` manages to be redundant and ambiguous at the same time. Definitely wouldn't want to guess what that might do.
you are right. so it is the savefileandoverwriteexisting() api, with a bug. I stand corrected.