16 parallel Claude agents build a 100,000-line Rust C compiler that builds Linux, for ~$20,000
An Anthropic researcher ran 16 Claude Opus 4.6 agents in a simple loop harness, each in its own container, coordinating through git and lock files with no orchestrator. Over nearly 2,000 Claude Code sessions in two weeks they wrote a clean-room C compiler in Rust with no internet access. It builds a bootable Linux 6.9 on x86, ARM and RISC-V and compiles QEMU, FFmpeg, SQLite, Postgres, Redis and Doom. Most of the human effort went into tests and the harness.
The numbers (as reported)
| API cost | Just under $20,000 |
|---|---|
| Duration | ~2 weeks, nearly 2,000 Claude Code sessions |
| Output | 100,000-line compiler |
| Tokens | 2B input, 140M output |
| Test-suite pass rate | 99% on most suites incl. GCC torture tests |
Facts
- Company / subject
- Anthropic (Nicholas Carlini)
- Tools
- Claude Code, Claude Opus 4.6
- Codebase
- greenfield
- Work type
- New product (research)
- Stack
- Rust, C
- Published
- 2026-02-05
- Last checked
- 2026-10-18
Caveats
Vendor-published capability stress test, not a product. Calls out to GCC for 16-bit x86 real-mode boot. Its own assembler and linker are still buggy (the demo used GCC's). It isn't a drop-in compiler, and its output is less efficient than GCC with optimisations off. Rust quality is 'nowhere near' expert level. Late on, new features often broke existing ones. The author says he's uneasy about deploying software nobody has personally verified.