Anthropic published engineering blog post describing Scion migration, completed in five months
Following·New·first covered 13 Oct 2026·2 sources
Anthropic Replaces Git With In-House Scion VCS After 12x Merge Surge
The gist
The migration shows developer infrastructure designed for human-scale workflows becoming a bottleneck when AI agents generate code at high volume. The numbers Anthropic reported, a 12x increase in daily merges over roughly four months, illustrate the infrastructure demands that can follow from agentic coding at scale.
The full picture
Anthropic completed a migration away from Git to an in-house version control system called Scion, after daily code merges in its monorepo grew from roughly 2,500 in May 2026 to over 30,000 by September 2026. The growth was driven by AI coding agents rather than human developers. A team of seven engineers built Scion, which resembles centralized systems like Subversion rather than distributed Git, and completed the migration in five months. Anthropic also built a companion code review system called Antique as part of the overhaul. The scale involved roughly 25 million CI checkouts per day, which Anthropic said would amount to over 600 petabytes of naive Git traffic daily.
How it developed
Sources
Anthropic Twitter
Simon Willison
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