Threw out the old test harness. It was testing against a system layout that hasn't existed for months -- still referenced "proxy" and "node" as service names, still assumed a single-machine topology, still expected the old REST endpoints that got replaced with the binary protocol.
Starting clean. New harness talks to the coordinator and artifact server directly, uses real parquet files from the test fixtures, validates end-to-end. The old one was giving me green checkmarks for a system that no longer exists. That's worse than no tests at all.