Anthropic has moved its main internal monorepo off Git and onto Scion, a version-control system a seven-person team built over five months, the company said in an October 13 engineering post. A companion code-review tool is called Antique.

The driver was volume: merged changes rose from about 2,500 a day in May to more than 30,000 a day by September, a twelvefold jump Anthropic attributes largely to Claude writing and merging code. Git's model, built for human-paced work, became the bottleneck.

Scion is internal only — Anthropic says it is not a general-purpose Git replacement and will not be released as a standalone product. The company instead plans to share its architectural approach with GitHub, GitLab and open-source maintainers.