AI migrated legacy COBOL programs to Java, bugs included

Researchers have developed a novel "Locksmith Loop" method to validate AI-generated Java migrations of legacy COBOL programs by instrumenting both source and target code in test environments and using an iterative agent-based approach to systematically explore program branches. The method achieved nearly complete branch coverage on open-source programs and 91.90% coverage on a production-like COBOL program, while ensuring the generated Java matched the original COBOL behavior under deterministic parity checks.