Mistral AI shares agent-led modernization of a reservoir simulator's legacy code

Shared a case of using agents to modernize the legacy code of a European energy company's reservoir simulator. Says that, out of a 300,000-line Fortran 77 codebase with neither a test suite nor central documentation, 40,000 lines were ported to C++ in the first sprint. Before the migration, a harness for checking numerical equivalence was set up first; more than 100 agents were launched with the Vibe CLI to document the codebase, and Mistral OCR was used to process documents. The company claims it was not fully autonomous but a structured workflow, with roles split into planner, coder, tester and code quality reviewer, and with human review gates.