Anthropic merged 30,000 code changes a day, so it ditched git for in-house Scion in 5 months

ronbodkin · x · 2026-10-14

Anthropic details how Claude-driven coding output forced a rebuild of its source control. Key points:

Merges to its monorepo grew from 2,500/day in May 2026 to over 30,000/day by September; the bottleneck shifted from writing code to human-scale infrastructure (source control, builds, CI).
The team built Scion, an in-house version control system, and fully migrated off git in five months, plus shipping a code review surface (Antique), code search, and a rich source-control IAM system in the same window.
Engineer roles changed: reviewers now check the intent of changes rather than reading every line, and their job is understanding high-level design tradeoffs — often telling Claude "no" to prevent over-engineering for hypothetical concerns.
The case study is circular: Claude both caused the growth and enabled building the scalable replacement quickly.

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