Anthropic replaces Git with in-house Scion as Claude-generated code surges
Anthropic disclosed in an engineering blog post that it has moved its main monorepo off Git and onto an in-house version control system called Scion. Anthropic says merged code changes rose from about 2,500 per day in May 2026 to more than 30,000 per day by September, with main-branch history near 100 GB and CI performing roughly 25 million code checkouts daily; Scion moves operations such as commits, merges and history queries to servers while clients keep only limited caches. Anthropic's internal measurements put Scion's infrastructure CPU and memory use at about one two-hundredth of the Git mirror setup it replaced, with checkouts falling from minutes to seconds and CI saving about 25% of CPU capacity; the system was built by a seven-person team over five months with help from Claude, and Anthropic stresses Scion targets very large repositories and many online agents rather than serving as a general Git replacement.
Anthropic's account shows that as Claude-driven agents push tens of thousands of code merges a day, human-scale version control and CI infrastructure can become the bottleneck, prompting a rebuild of source control.
Updated October 15 to include more detail on the projects that pioneered many of the techniques we use in Scion.
At Anthropic, coding is no longer the bottleneck to building systems or doing research. Claude is able to autonomously iterate on research loops, micro-optimize complex programs, and build new services from the ground up at a speed and scale we haven’t seen before. The bottleneck, now, is all of the developer infrastructure built for human scale: source control, builds, and CI.
In May 2026, Anthropic averaged around 2,500 code changes merged per day; as of September, we merged over 30,000 per day. We don’t expect this rate of growth to slow down anytime soon; the latent demand for merging code is practically infinite, and every bottleneck we remove immediately leads to a further increase in the amount of code we produce.
