Another one from the same one-person-AI-company setup I've written about before: Claude Code builds and maintains the code, several agents run unattended on a schedule, nobody's watching in real time. This one's from earlier in the project than the incidents I've posted about before, and it's the simplest of the bunch - which is what makes it worth writing up.
The setup
A crypto trading bot polls a broker's API every 5 minutes, pulls the last hour of price bars, and decides whether to buy, sell, or hold based on recent price movement. Every cycle, it logs its decision - symbol, price, reasoning - to a file. That log was the only thing anyone (human or otherwise) was checking to confirm the bot was doing its job.
What actually happened
The code asked the broker's API for "the last N bars" by passing a limit parameter and nothing else - no explicit start time. That seemed like a reasonable way to ask for "the most recent bars." It wasn't. Without an explicit start time, the API silently returned a fixed window - bars starting from midnight UTC that day, sorted oldest-first - instead of the most recent N bars. Two very different requests that happen to share a limit parameter, with no error, no warning, nothing in the response shape that would tip you off.
