[WorldMaker]

Having been involved in various roles of double entry accounting adjacent tools, the next level up is realizing that it is easier to display the correct sign if you store things unsigned and use debit/credit nomenclature even in your DB model/codebase. It's not just that this makes it easier to talk to the accountants using your system about the internals of that system, but that showing the right sign becomes simple "pattern matching" based on entirely on the type of account and the user's type. There's no "math" involved to switch signs based on how it is "stored" in the codebase, the displayed signs are always a UI element that is clearly dependent on its inputs.

The centuries of accountant's aversion to using negative numbers in day to day accounting usage has abstraction uses even in your codebase.