Anthropic replaces Git with in-house Scion system as daily merges top 30K
Anthropic detailed its migration from Git to Scion, an in-house version control system built by seven engineers with Claude in five months, to handle a surge in daily code merges from about 2,500 in May 2026 to over 30,000 in September. The company also developed Antique, a new code review system, and migrated its entire monorepo to Scion, citing Git's decentralized design as a bottleneck for its growing workload.
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Anthropic Engineering
As our merges per day grew more than tenfold, source control became our biggest development bottleneck. Here, we share how we migrated to an in-house version control system in five months.
Techmeme
Anthropic : Anthropic details Scion, a git replacement for its monorepo, built by seven engineers with Claude in five months, as daily merges rose from 2.5K in May to 30K+ — As our merges per day grew more than tenfold, source control became our biggest development bottleneck.
Simon Willison
Redesigning source control at Anthropic Interesting piece from Anthropic describing why and how they built their own custom alternative to Git, based on the dramatic increase in rate of changes to their code after the past six months. In May 2026, Anthropic averaged around 2,500 code changes merged per day; as of September, we merged over 30,000 per day. They included a chart showing those changes. I had Claude modify their chart ( code here ) to add markers for the public releases of each of their models in 2026: This shows public release dates, not the date when models became available for Anthropic's internal use. My guess is that the introduction of Fable/Mythos class models is a key factor in the increased coding velocity. "Antique" is their new code review system. The source control system is called Scion, and sounds to me like a reinvention of centralized source control along the lines of Subversion. They had some pretty extreme requirements: The history of our main branch alone
机器之心机器之心
Git，这个统治程序员 20 年的版本控制工具，竟然被 Anthropic 自己造的新系统替换了。 而完成这一切的，只有 7 名工程师和深度参与开发的 Claude。 5 个月，Anthropic 从零开发出了内部源代码控制系统 Scion、配套的代码审查工具 Antique 以及其他多个相关系统，并完成了整个单体代码仓库从 Git 到 Scion 的迁移 。 这意味着什么？几个人借助 AI，仅需要数月，就造出一套新系统，把自家内部用了多年的 Git 直接换掉了。简直太夸张了！这就不由得有人发出了「RIP GIT」的感叹。 为什么要自己造一套 Git 替代品？ 原因很简单，Anthropic 的 AI 编程规模已经大到原有开发基础设施快撑不住了。 Anthropic 给出的数据显示，今年 5 月，其平均每天合并约 2500 次代码变更。到了 9 月， 这个数字已经突破 3 万次 ，短短 4 个月增长了 12 倍以上。并且，Anthropic 预计，这种增长短期内不会放缓。代码合并的潜在需求几乎没有上限，每当解决一个瓶颈，代码产出量就会进一步增加。 在现实的倒逼下，Anthropic 开发了内部版本控制系统，并在五个月内将整个 Monorepo（单体代码仓库）从 Git 完整迁移到 Scion。 Anthropic 在最新的博客中完整介绍了整个流程。 一、不断膨胀的 Monorepo 在介绍 Scion 之前，有必要先说明 Anthropic 的工作负载有多特殊。其使用 Claude 编写软件的程度，远远超过绝大多数公司。其中，那些为人类开发规模设计的工具在哪些地方开始吃力。源代码控制只是其中一个例子。 Anthropic 预计，短期内不会有太多公司遇到同样的问题。但随着 AI 编程工具越来越普及，其他公司应该也用不了多久就会碰到类似的瓶颈。这也是我们决定分享 Scion 的设计和开发经验的原因。 Git 是一个去中心化系统。每次克隆都会得到一份完整、独立的代码仓库。即使完全离线，开发者也能计算代码差异、查看提交历史、追踪某一行代码的修改记录以及检出任意版本。对绝大多数代码仓库来说，这套设计非常合理，也是 Git 成为行业标准的重要原因。 但随着 Anthropic 的 Monorepo 不断增长，Git 的设计越来越难以满足需求。目前，仅主分支的历史数据就接近 10
