A case study watched one agent build a real data system against a fixed spec and catalogued the failures.

arXiv 2609.01985 fixes storage technologies, schema, entity-resolution algorithm and retrieval-filtering strategy in advance, then characterizes how a coding agent behaves on systems-level requirements: schema design, async orchestration, configuration correctness, retrieval-filtering tradeoffs. It's a defect taxonomy for the class of work agents are increasingly handed end to end, and the defects it finds are ones a passing test suite doesn't surface.