Even top models miss errors in over half of buggy code submissions.

UOJ-Bench uses real competitive-programming submissions to test generation, error-finding, and repair. In single-attempt evaluation, top models fail to identify errors in over 50% of incorrect submissions (arXiv). Test-time scaling pushes success above 90%, but models also flag problems in more than 5% of perfect submissions. So your code-judging agent both misses real bugs and invents fake ones, and only multi-attempt scaling rescues it. Single-pass agent code review is unreliable by the numbers.