AI
Redesigning source control at Anthropic
Publication: Simon Willison's Weblog
Author: Not available in collected metadata
Source published: 13/10/2026, 23:00:06 UTC
Briefing created: 25/10/2026, 02:53:24 UTC
Based on a feed excerpt; full article content has not been acquired. Source evidence retrieved 15/10/2026, 00:27:24 UTC.
Briefings
Anthropic redesigned its source control system from Git to Scion in five months to handle a 25-fold increase in daily code changes from 2,500 to 30,000 in September 2026. The system supports massive data volumes, with main branch history exceeding 100 GB and working copies over 25 GB, requiring 25 million code checkouts daily for CI. The migration was completed by a seven-person team, and the system prioritizes online access for the primary Claude user. Key uncertainty remains regarding the specific impact of the introduction of Fable/Mythos class models on the coding velocity trend.
Key points
- Anthropic migrated from Git to Scion in five months to manage a 25-fold increase in daily code changes, rising from 2,500 to 30,000 per day by September 2026.
- The new system handles massive data volumes, with main branch history exceeding 100 GB and working copies over 25 GB, requiring 25 million code checkouts daily for CI.
Context
Anthropic's source control system, Scion, was developed to address a dramatic surge in code changes following the past six months. The project involved a seven-person team and prioritized online access for the primary Claude user, as offline support was deemed unnecessary for the heaviest user. The system was inspired by prior art from Google's Piper and Meta's Sapling, with core concepts derived from Mononoke.
Limitations
The evidence covers the migration timeline and technical requirements but lacks specific data on the impact of the Fable/Mythos model introduction on coding velocity. The article notes that while adversarial review is effective, it can be myopic, leaving the long-term stability of the new system uncertain without further testing.
Generated by Bittrees-hosted qwen35-2b sha256:aaf42c8b7c3c on 25/10/2026, 02:53:24 UTC. Based on publisher-provided feed evidence; may not cover the full original article. Check the source for details.
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