Tools · Updated 14 Oct, 04:30 am IST
Anthropic replaces Git with Scion to handle massive code growth
Why it matters for readers: It explains why a company would stop using Git and build bespoke source control when code output increases dramatically.
- Anthropic migrated its monorepo from Git to an in-house system named Scion, completing the migration in five months.12
- The company also built a new code review surface called Antique, plus code search and IAM tooling to support the change.12
- Merged changes grew from about 2,500 per day in May 2026 to over 30,000 per day by September 2026, driving the redesign.12
- Anthropic’s engineering team reported extreme scale requirements: the main branch history is almost 100 GB and CI performs on the order of 25 million checkouts per day.2
- A seven-person team built Scion, and the migration aimed to address infrastructure not designed for machine-scale code generation and CI.12
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13 Oct, 09:19 pm · Hacker News (100+ points)
Redesigning source control at Anthropic
14 Oct, 04:30 am · Simon Willison
Redesigning source control at Anthropic