Claude's C Compiler (CCC)
A from-scratch, dependency-free C compiler in Rust, written by parallel Claude Code agents running Claude Opus 4.6, capable of building Linux 6.9 and other large C projects.
Anthropic's research post describes 16 agents, nearly 2,000 Claude Code sessions, and about $20,000 in API cost. The repository states that aside from one human-written paragraph, 100% of the code and documentation was written by Claude Opus 4.6. A human wrote test cases but did not pair-program or give code-quality feedback.
Human involvement
Mostly written by agents. A human wrote tests the agents were told to pass and designed the parallel harness, but did not interactively pair-program or review code quality during development.
Evidence
- Official blog
Over nearly 2,000 Claude Code sessions and $20,000 in API costs, the agent team produced a 100,000-line compiler that can build Linux 6.9 on x86, ARM, and RISC-V.
- Official repository
With the exception of this one paragraph that was written by a human, 100% of the code and documentation in this repository was written by Claude Opus 4.6.
Notes
Included as the best-documented Claude-code systems landmark, even though this seed set emphasizes non-Claude work. The README warns the compiler is not validated for correctness and is not recommended for use.