Henrik encountered a persistent bug where a third-party service provided inconsistent results. Updates sent by Henrik's company sometimes didn't reflect correctly, and reads showed inexplicable data. The vendor initially blamed Henrik's team, but Henrik was unconvinced. He collaborated with colleagues and the vendor, developing reproducible test cases over several weeks. These tests strongly suggested the vendor's service was at fault. After a period of silence, the vendor's product owner acknowledged the issue. They identified the root cause as the API occasionally misidentifying record ownership. Their proposed solution was to implement unique, never-repeating IDs for entities. This innovative approach was, in fact, the well-established concept of primary keys and unique identifiers. The vendor, despite the common knowledge of these concepts, had apparently been unaware of them.