Modernizing complex legacy code with AI agents.

Mistral AI · 1 month ago · 42

Mistral and a European energy operator used AI agents to migrate a physics reservoir simulator from Fortran 77 to C++ while adding a documentation pipeline and a numerical parity harness. The project migrated 40,000 lines of Fortran 77 and used checkpoints to verify that key outputs matched, including an example RHOG value of 42.71834. They changed the workflow from fully autonomous subroutine-by-subroutine translation to structured, module-by-module agent collaboration with human review gates and PR-level verification.