... and today we've discovered that the input field on which I've been relying to link data between two systems is, in fact, not shared between those systems. It _can_ be, but there's no mandate that it must, so our hit rate is low teens. Because everything is a manual process and nobody has a consistent data model and my project relies on interoperability between those systems.
I'm unconscionably angry right now, because I was so hung up on whether or not I'd be able to interface with the old legacy system that I never stopped to ask whether the new system would be feeding me the data I needed to make the old system do stuff. And it _can_, but it presently... isn't.
So right now, I'm working with one of my coworkers to create an encoding scheme so we can encode the data we need, which contains spaces into a data tag we can append to the data we're already getting through a system which strips spaces, so that we can unmunge the data ourselves on the receiving end to get back the string we need to do the lookup to get the data we actually need so we can execute the function we have to call without having to rely on the legacy system's internal GUIDs.
The long-term solution is to make the remote system do the lookup in the legacy system and fetch the internal GUID for us, but that could take three weeks and I can get this hack done today. And the real long-term goal is to get off the legacy system with its internal GUIDs, but we can't afford to do that if we can't make these legacy calls in the meantime to let us not have to reinvent the entire system from scratch before we use it.