Filing45 publishes every stock trade disclosed by members of Congress, the fund managers who file 13Fs, and the executive branch — each row linked back to the filing it came from. This post is not a feature tour. It is about the architecture: why the system is shaped the way it is, which constraints did the shaping, and where I got it wrong first. The short version: almost every design decision in this system was forced by the documents, not chosen.