The fixture encoded the sidecar as `record: "absent" | {...}`, which collapsed two states that are different on disk: no `<stem>.jsonl` file at all, and a file that exists carrying no processing-record key. Two rows encoded identically, so a consumer rebuilding the fixture to reproduce its verdicts could not construct the state one of them describes -- and adding an audio no-sidecar case later would have collided silently. It is now `sidecar: "absent" | "header-only" | {...}`, three distinguishable states, with the distinction stated in the generator next to the encoding. All 23 rows now have distinct shapes, checked. Found by verifying that a planned consumer could actually rebuild each row before writing a test that assumes it, rather than after.