The detection story here is what's interesting from an SRE perspective. A 200 OK with truncated data and no error logs is about the hardest class of bug to catch with standard monitoring — your error rate is flat, your latency looks normal, and the only signal is a customer saying "my image is broken."

The race condition aspect makes it worse: it only triggers when the reader is slower than the writer, which in production means it's intermittent and load-dependent. The kind of thing synthetic monitoring almost never catches because your test client is usually fast.