Scion

Anthropic migrated its monorepo from Git to Scion, an in-house server-side source control system built on content-addressed storage and tiered caching to serve agent and CI workloads. Daily merged changes grew from roughly 2,500 in May to over 30,000 in September, with CI performing about 25 million checkouts per day, outpacing shallow clones, sparse checkout and mirror-based Git workarounds. The design trades offline independence for less local data and shared infrastructure.