Mistral AI5 min read
Legacy code modernization with AI agents
Mistral's 40,000-line Fortran rewrite shows where agent autonomy runs out
Mistral moved 40,000 lines of Fortran 77 to C++ for an unnamed energy client and published the workflow. Its first attempt, run by fully autonomous agents, produced Fortran retyped in C++ syntax. Numerical parity checks and a human in the loop fixed that.
2026-09-19