Another banger by the Anthropic Engineering team. The mass-parallelized 16 Claude instances to build a full C compiler from scratch. 100,000 lines of Rust. Compiles the Linux kernel. No active human supervision. The wildest part isn't even the compiler itself. It's that they built a system where agents autonomously pick up tasks, lock files to avoid conflicts, and git sync with each other like a remote dev team. Looks inspired by Ralph Loop. 2 billion input tokens, 140 million output tokens, 2 weeks, and $20k in total cost. If you're still writing code one file at a time in a single session, you are massively underestimating where this is headed. Agent swarms that coordinate on real codebases aren't a thing of the future anymore. They're a right now thing. 2026 is shaping up to be the year of agent harnesses. And the cool part is that you can go and build your agent team with Claude Code now.