On October 13, 2026, Anthropic published "Redesigning source control at Anthropic". It opens with the claim that "coding is no longer the bottleneck". The new bottleneck, it says, is developer infrastructure built for human-scale source control, builds and CI. On Hacker News the post reached more than 850 points and 950 comments.
The numbers that broke git
- "In May 2026, Anthropic averaged around 2,500 code changes merged per day". By September, "we merged over 30,000 per day".
- CI alone ran "on the order of 25 million code checkouts per day". Fetched naively, the post estimates "over 600 PB of git traffic per day".
- Git is decentralised, so every clone is a full repository. But almost all of Anthropic's clients are always-online agents and jobs, so that design added cost without benefit.
The replacement, Scion, moves history, merges and rebases to the server. Clients keep a bounded cache and fetch files on demand, and many CI jobs never check out at all. A code review tool, Antique, was built alongside it. Anthropic reports infrastructure "200x smaller than our previous git mirroring infrastructure", checkouts "in seconds rather than minutes", and a full migration of the monorepo "from git in five months" by "A team of seven people". The post is clear that this is not for everyone: "Scion is by no means a suitable replacement for git for general use." Anthropic says it is sharing the design "so that we can partner with GitHub, GitLab, and the OSS community."
The line everyone quoted
Claude wrote much of the system. The post's most discussed passage is about what the engineers did: "Very often, we found that the role of the engineers was to tell Claude 'no.'" It explains that "Agents will sometimes violate core system constraints to satisfy a pattern". Its examples include systems that found merges by scanning the commit log linearly instead of asking the code review tool. Engineers, it says, now examine "the intent of the change as opposed to reading every line of code".
Why this is a trend
The Hacker News thread argued about consequences more than about git. One commenter said that whenever they stop reviewing Claude's code, "I later find janky crap." Another: "Anthropic is first and foremost trying to sell you something." Others saw a wave of rebuilt tools coming because "AI makes writing code significantly cheaper", and worried about "A world where starting is incredibly easy and finishing is more complicated than ever". It continues a debate this digest covered the day before, about whether capability has outrun the tooling around it.
I read this post as an infrastructure warning more than a git story. A twelvefold rise in merges in four months is what agent-driven development looks like once it works. Every system built on the assumption that humans write code slowly, from source control to CI capacity to code review, starts to fail at the same time. Most teams are nowhere near 30,000 merges a day, and Anthropic itself says Scion is not a general git replacement, so I would not copy the system. I would copy the questions. Which of our tools assume a human pace? What does our CI bill look like at ten times today's merge volume? And who on the team is responsible for saying "no"? That last point matters most. The post's own examples are agents taking shortcuts that pass a local check and break a system-wide rule. Reviewing intent instead of every line only works if someone writes those rules down and enforces them in tests and architecture, not just in reviewers' heads. The commenters who still find "janky crap" are describing what happens without that.
Anthropic's October 13 post says agent-driven merges rose from about 2,500 to over 30,000 a day between May and September 2026, so a team of seven built Scion, a server-side version control system, and migrated off git in five months; its line that engineers very often had to tell Claude 'no' drove a 950-plus-comment debate.