Anthropic moves away from git to its own version control system, Scion

Anthropic moves away from git to its own version control system, Scion

According to Anthropic’s engineering blog, the company has stopped using git in its monorepo and adopted Scion, a proprietary version control system designed for AI agents.

Thanks to agents, the number of changes merged into its monorepo each day now reaches 30,000; in May it was around 2,500. Decentralized git cannot handle this volume because every clone must contain a full copy of the repository. That is convenient for humans, but because agents generate huge amounts of code, Anthropic estimated that without optimization it would cost roughly 600 PB of traffic per day.

The company first tried mirrors, snapshots, and partial clones, but the architecture scaled poorly. Over five months, Anthropic moved entirely to its own product, Scion.

Scion works as an always-available server that stores and computes history, commits, and merges, then exposes them through an API. Agent clients need only a small cache and the files they actually use.

The product was developed by a team of just seven people, using Mythos and other models. They also built Antique, a code-review tool designed specifically for agents.

The bad news is that Scion will not be open source.

Anthropic states directly that Scion is not meant as a general replacement for git; it was built for Anthropic’s own needs: a massive monorepo, swarms of agents, and a huge token budget. Still, the post gently suggests that the git team should consider change: in the age of AI agents, infrastructure built for humans is gradually becoming the main bottleneck.