Ladybird Rust Port: Methodology for Large-Scale Agentic Engineering

ladybird.org — 25,000 lines of Rust written in approximately 2 weeks using Claude Code and OpenAI Codex. The methodology is the story: comprehensive test suite written first (by humans), human-directed architecture decisions, bounded scope per agent session (small focused prompts), and hundreds of small prompts rather than a few large ones. Success factors align perfectly with Willison's guide and the TDD convergence. This is the proof that agentic engineering scales to production-critical systems when the methodology is right.