# Anthropic replaces git with in-house system Scion for agent-scale code

Digest AI · Enterprise & Industry · published 2026-10-13T15:49:56Z

Canonical: https://digestai.news/story/anthropic-replaces-git-with-in-house-system-scion-for-agent-scale-code

## Summary

Anthropic has migrated its entire monorepo from git to a custom version control system called Scion, driven by the explosive growth in AI-generated code. The company reports that daily merged code changes surged from around 2,500 in May 2026 to over 30,000 by September. This volume strained traditional infrastructure, as the main branch history alone approached 100 GB, and daily CI checkouts reached 25 million, creating an estimated 600 PB of git traffic if fetched naively.

The new system, Scion, was designed specifically for agents that are always online, abandoning git’s decentralized, offline-first model. Instead, Scion uses a client-server architecture where the server handles commits, merges, and history queries, while clients maintain only sparse, on-demand working copies. This approach eliminates the need for large local repositories and allows for horizontal scaling without the maintenance burden of packfiles or internal mirrors.

Anthropic built Scion, along with a code review tool named Antique, in five months. The company notes that while few organizations face such extreme scale today, the pressure points identified are likely to become common as AI coding tools become more widespread. The shift highlights how developer infrastructure must evolve to support autonomous software development at machine speed.

## Key points

- Anthropic migrated its monorepo from git to an in-house system called Scion in five months.
- Daily merged code changes increased from 2,500 in May 2026 to over 30,000 in September.
- Scion uses a client-server model designed for always-online agents, replacing git's decentralized offline approach.

## Why it matters

This marks a significant shift in developer infrastructure, showing that traditional tools like git are becoming bottlenecks for AI-driven development. It signals that future software engineering workflows will require systems optimized for autonomous, high-volume code generation rather than human-paced editing.

## Sources

1. [Redesigning Source Control at Anthropic](https://anthropic.com/engineering/redesigning-source-control) (anthropic.com, 2026-10-13, primary source)

## Cite

Digest AI, "Anthropic replaces git with in-house system Scion for agent-scale code", 13 October 2026, https://digestai.news/story/anthropic-replaces-git-with-in-house-system-scion-for-agent-scale-code

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