While building LogicVisor's review system, I was faced with a question I hadn't thought about before: what would happen if users submitted duplicate algorithm solutions?
I decided to test it myself. I submitted a solution to a simple palindrome challenge. The request went through, my solution was reviewed correctly. Normal happy stuff. Then I submitted the exact same solution a second time. And the normal happy stuff happened again. But I was far from happy.
That duplicate submission meant more tokens spent, more database memory consumed, more remote procedure calls, more AI calls, and more waiting time. For a problem that had already been solved.
I shuddered at the thought of a bad actor effectively DOS-ing my site or running up my AI bill just by hammering the same solution repeatedly. Rate limiting controls the number of requests per client — but it has nothing to do with the content of those requests. A user could stay well within their rate limit and still abuse the system by submitting the same code over and over.
This wasn't going to work. I needed a way to identify duplicate submissions and return a cached response instead of processing everything from scratch. Which led me to a more interesting question: how do you actually detect identical code?
