Redesigning source control at Anthropic
Points and comments are a snapshot, not live.
Anthropic built Scion, a server-centric VCS, to handle AI-driven code growth.
Anthropic's monorepo growth from 2,500 to 30,000+ daily merges by September 2026 made git unsustainable. The 100 GB history and 600 PB daily checkout traffic prompted Scion, a custom VCS designed for always-online AI agents. Scion uses a write-ahead log of changesets, server-side operations, and horizontally scalable infrastructure. It eliminated packfiles and mirrors, achieving 200x less CPU/memory and 25% CI capacity gains. A team of seven built Scion and the Antique code review tool in five months, aided by Claude itself to optimize critical pipelines.
What commenters are saying
Commenters drew parallels to centralized systems like SVN and Perforce, noting Anthropic reinvented that paradigm for agents. Some questioned the 100 GB monorepo size, suspecting agents misuse git history as a message queue. A notable exchange involved the Anthropic team confirming they review agent actions to prevent such misuse. Others highlighted the advantage of in-house AI for optimizing pipelines, though some cautioned that speed and memory gains matter less when the original is already adequate.