From the source
Google says its Antigravity agent, using Gemini 4 Argon, migrated the core of a 174,000-line Fortran coastal ocean model into memory-safe Rust in 59 minutes.
- The company picked FVCOM, a widely used coastal ocean simulation with 174,774 lines of Fortran 90 and C across 264 files, and gave the agent one prompt with four hard rules.
- Those rules required zero unsafe blocks, no heap allocations in hot loops, Rust files under 400 lines, and 95% branch coverage with zero numerical difference across 100 randomized seeds.
- The run had three stages: an 11-minute baseline capture that compiled the original Fortran with gfortran -O3, a 3-minute audit of all 264 files, and a 45-minute Rust port.
- During the port the agent scaffolded the Cargo workspace and rewrote the core solver into 13 Rust modules, each under 240 lines.
- Google says the agent caught six decades-old bugs, cut memory usage in half, and sped up simulations by 1.88x, and it is releasing the workflow as an open-source skill.
