Redesigning source control at Anthropic
- ID
- 35064
- Status
- summarized
- Published
- 14 Oct 2026, 7:00 AM
- Fetched
- 15 Oct 2026, 8:45 AM
- Provider
- Simon Willison
- Category
- developer-ai
- Original URL
- https://simonwillison.net/2026/Oct/13/redesigning-source-control-at-anthropic/
- Source URL
- https://simonwillison.net/atom/everything/
Summary
- Score
- 8.0
- Created
- 15 Oct 2026, 8:46 AM
- Tags
- Audience
- developersai_agent_usersai_ml_learnersvibe_coders
What happened
Simon Willison flags an Anthropic write-up on why it replaced Git with a custom centralized system called "Scion", plus a new code review system called "Antique". Anthropic says it went from roughly 2,500 merged code changes per day in May 2026 to over 30,000 per day by September 2026, with a main-branch history near 100 GB, a compressed working copy over 25 GB, and about 25 million CI checkouts per day that would have meant 600 PB of naive git traffic daily. A seven-person team finished the Git migration in five months, and Willison adds his own note that adversarial model review tends to over-engineer unless engineers steer it.
Why it matters
If you run CI or agent sandboxes that clone repos, the 25 million daily checkouts and 600 PB/day naive-fetch figure is the number to check against your own setup: full clones per job stop scaling well before repo size hits Anthropic's 100 GB history, so shallow/sparse clones, a shared checkout cache, or a non-Git store for CI become concrete options rather than hypotheticals. The adversarial-review note is the other decision point: if you point one model at another model's diff, budget human time to reject fixes for hypothetical problems, because Anthropic reportedly had to steer Claude away from over-engineering. Nothing in this item is Malaysia-specific, so treat it as general engineering signal.
Discussion angle
At what repo size or merge rate does Git + full-clone CI stop working for you, and would you rather fix it with shallow clones and caching or follow Anthropic's route of a purpose-built centralized system?