Except that, as mentioned, this was a software design document and not a legal document. I described intended behavior of a software component. There's no ambiguity in using "will" or "shall" since software does not (at least did not at that time) have intent and does not make promises.

I tried to avoid argument because it didn't matter, not because I thought my word choice was incorrect. It was an internal document describing intended software behavior, to help the poor soul who had to maintain that code.

"When 'shall' is used to describe a status, to describe future actions, or to seemingly impose an obligation on an inanimate object, it's being used incorrectly."[0]

[0]https://law.utexas.edu/faculty/wschiess/legalwriting/2005/05...