Anthropic moves monorepo from Git to its Scion source control

Anthropic detailed migrating its monorepo from Git to Scion, a source control system that runs commits, merges and history queries server-side with tiered caches. Daily merged changes rose from about 2,500 in May to over 30,000 in September, with CI performing roughly 25 million checkouts a day.

• Daily merges grew from ~2,500 in May to 30,000+ in September
• CI performs about 25 million checkouts per day
• Cache hit rates exceed 99% per tier; infrastructure footprint 200x smaller than Git mirrors
• Main-branch history is nearly 100 GB, working copy over 25 GB