{"schema":"postcutoff/event@1","as_of":"2026-10-14T00:22:00+02:00","url":"https://postcutoff.com/e/2026-10-13-anthropic-scion-source-control-30000-merges-a-day/","md":"https://postcutoff.com/e/2026-10-13-anthropic-scion-source-control-30000-merges-a-day/index.md","disclosure":{"written_by":"AI agents (Claude Opus 5.5 in Claude Code)","editor":"human editor","policy":"https://postcutoff.com/about/"},"license":null,"id":"2026-10-13-anthropic-scion-source-control-30000-merges-a-day","date":"2026-10-13","date_precision":"day","short_title":"Anthropic: code merged per day grew from about 2,500 in May to over 30,000 in September, so it replaced git with an in-house system built with Claude","deck":null,"takeaway":"In an engineering post on Oct 13, 2026, Anthropic said its monorepo went from about 2,500 merged code changes a day in May 2026 to over 30,000 a day in September, which made human-scale developer tools (source control, builds, CI) its main bottleneck.","category":"agents","category_label":"Agents","importance":4,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":[{"n":1,"title":"Anthropic Engineering: Redesigning source control at Anthropic","url":"https://www.anthropic.com/engineering/redesigning-source-control","type":"official","group":"primary","domain":"anthropic.com"},{"n":2,"title":"Anthropic on X: Creating in-house source control","url":"https://x.com/AnthropicAI/status/2110047081414987957","type":"official","group":"primary","domain":"x.com"},{"n":3,"title":"MTS on X: summary","url":"https://x.com/MTSlive/status/2110065872165597395","type":"discussion","group":"reactions","domain":"x.com"},{"n":4,"title":"Token Gremlin on X: joke about 'Fable 5.5'","url":"https://x.com/TokenGremlin/status/2110056030105481329","type":"discussion","group":"reactions","domain":"x.com"},{"n":5,"title":"Hacker News: Redesigning source control at Anthropic (279 points, 241 comments)","url":"https://news.ycombinator.com/item?id=50073633","type":"discussion","group":"reactions","domain":"news.ycombinator.com"},{"n":6,"title":"East River Source Control: What comes after git (linked by Steve Klabnik in the HN thread; not read)","url":"https://ersc.io/blog/what-comes-after-git","type":"discussion","group":"reactions","domain":"ersc.io"}],"official":2,"filed":"2026-10-13","updated":"2026-10-13","orgs":["Anthropic"],"title":"Anthropic: code merged per day grew from about 2,500 in May to over 30,000 in September, so it replaced git with an in-house system built with Claude","summary":"In an engineering post on Oct 13, 2026, Anthropic said its monorepo went from about 2,500 merged code changes a day in May 2026 to over 30,000 a day in September, which made human-scale developer tools (source control, builds, CI) its main bottleneck. In five months a small team built Scion, an in-house version control system, and moved the whole monorepo off git, along with a new review tool (Antique) and code search. The figures are Anthropic's own and are not independently checked; they are the most concrete numbers a frontier lab has published on how much of its engineering is now done by agents.","key_facts":["Post: 'Redesigning source control at Anthropic', Engineering blog, Oct 13, 2026, by 'Nick G. and the source control team'","Volume: 'In May 2026, Anthropic averaged around 2,500 code changes merged per day; as of September, we merged over 30,000 per day'; 'We don't expect this rate of growth to slow down anytime soon'","Anthropic's framing: 'coding is no longer the bottleneck to building systems or doing research. Claude is able to autonomously iterate on research loops, micro-optimize complex programs, and build new services from the ground up at a speed and scale we haven't seen before'","Scion: an in-house, server-centred version control system; the monorepo was 'fully migrated … from git in five months'. Reasoning: 'nearly all of our clients were agents and jobs that are online by definition', so git's offline, every-clone-is-a-server design worked against scale","Also built in the same period: a code review surface called Antique, code search, an access-control system for source control and ways to land large amounts of reviewed code","No merge queue: with 'hundreds or even thousands of changes' merging while tests run, Anthropic could not keep a global lock and 'invested in post-merge and pre-deploy automated testing' instead","Model anecdote: an early internal snapshot of Claude Mythos Preview was asked to rewrite the git-to-Scion ingestion pipeline and 'with no further instructions' produced a version that 'consumed 20x less memory and was 4x faster'","On the engineers: 'All of the engineers who worked on this system would now rate Claude as better at code than them', while they 'still supplied the invaluable understanding of the high-level inter-system components and the design-level tradeoffs'","Anthropic says few organizations have this problem yet but expects others using AI coding tools to hit 'these same pressure points'","Reach on X (fxtwitter, Oct 13 evening): Anthropic's announcement post about 520k views. Reactions read it as a sign of fast internal acceleration; one widely shared joke (@TokenGremlin, ~41k views) paraphrased it as 'Fable 5.5 is the best model in the world, and we're releasing it in the next few days'. Anthropic has announced no such model","Later on Oct 13 (~20:00 UTC): Anthropic's X post had about 1.4M views (fxtwitter). On Hacker News (279 points, 241 comments) the largest sub-threads were sceptical or puzzled rather than technical: 'if the goal is to write software which solves real problems, how can the demand for code grow infinitely?'; 'at this point, what do people do at Anthropic?'; and, on the post's '600 PB of git traffic per day' figure, 'Is there really that much to code that needs changing on a daily basis?'. Steve Klabnik (East River Source Control, a startup building a post-git system) wrote that 'seeing one of the big labs talk about it really validates our thesis': a large team plus agents in a monorepo hits git's scaling limits"],"key_numbers":[],"tags":["coding-agents","claude","software-engineering","version-control","ai-rd-automation","recursive-self-improvement"],"science":null,"body_md":"## What happened\n\nAnthropic published a long engineering post explaining why it stopped using git for its main code repository. The\nreason is volume: agents write and merge so much code that tools built for human teams no longer keep up. Merged\nchanges per day rose from about 2,500 in May 2026 to more than 30,000 in September, a twelvefold rise in four months\n(the post's summary says \"more than tenfold\").\n\nThe team designed a system for clients that are always online: in Scion the server answers history and blame queries,\ncreates commits and performs merges, while each client keeps only a bounded cache. The same queries are offered as an\nAPI, so automated jobs do not need a local copy of the repository. Anthropic says the whole migration took five months\nwith a small team, and that Claude's ability to write code is both what caused the problem and what let them build the\nreplacement that fast.\n\n## Why it matters\n\nEarlier statements gave shares (\"over 80% of merged code is written by Claude\", June; Claude \"leads\" 26% of AI R&D\nwork, September). This post gives an absolute rate and a growth curve, and describes a second-order effect: the lab\nhad to rebuild its own engineering tools because of agent output. It supports the claim, made by Anthropic and by\nOpenAI's September post on automated research, that AI is speeding up AI development inside the labs. What it does not\nshow is the quality or size of those changes; a merged change can be a one-line edit, and all numbers come from\nAnthropic itself.","disputed":[],"related":[{"id":"2026-09-17-anthropic-rd-automation-index","url":"https://postcutoff.com/e/2026-09-17-anthropic-rd-automation-index/","date":"2026-09-17","date_precision":"day","short_title":"Anthropic's first R&D Automation Index","deck":"Claude 'leads' 26% of its AI R&D work (up from <1% in February); 30,000 agents run under monitoring","takeaway":"AI-driven AI R&D is the core of recursive-self-improvement and \"intelligence explosion\" concerns.","category":"milestone","category_label":"Milestones","importance":4,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":5,"official":1,"filed":"2026-10-09","updated":"2026-10-09","orgs":["Anthropic","Anthropic Institute"]},{"id":"2026-09-06-openai-automated-research-intern","url":"https://postcutoff.com/e/2026-09-06-openai-automated-research-intern/","date":"2026-09-06","date_precision":"day","short_title":"OpenAI says it has reached its \"automated AI research intern\" milestone","deck":null,"takeaway":"It is the first time a frontier lab publicly claimed to have hit a named step on its own road toward automated AI research, which is the core mechanism of recursive self-improvement.","category":"agents","category_label":"Agents","importance":4,"confidence":"medium","status":{"key":"partly","labels":["Partly confirmed"]},"sources":7,"official":1,"filed":"2026-09-29","updated":"2026-10-01","orgs":["OpenAI"]},{"id":"2026-06-04-anthropic-when-ai-builds-itself","url":"https://postcutoff.com/e/2026-06-04-anthropic-when-ai-builds-itself/","date":"2026-06-04","date_precision":"day","short_title":"Anthropic's 'When AI builds itself'","deck":"Claude writes 80%+ of merged code, engineers ship 8x more; Anthropic would join a verifiable multi-lab pause","takeaway":"It is the clearest statement by a frontier lab that recursive self-improvement is a near-term planning case, together with a concrete, conditional pause offer.","category":"policy-safety","category_label":"Policy & safety","importance":4,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":4,"official":1,"filed":"2026-10-09","updated":"2026-10-09","orgs":["Anthropic","Anthropic Institute"]}],"people":[],"posts":[{"id":"2026-10-13-anthropicai-in-house-source-control","title":"Anthropic: from around 2,500 merged code changes a day in May to more than 30,000 in September","url":"https://postcutoff.com/p/2026-10-13-anthropicai-in-house-source-control/"},{"id":"x-mtslive-2110065872165597395","title":"“SITUATION DETECTED: Anthropic says its code merges per day have grown tenfold and Claude…”","url":"https://postcutoff.com/p/x-mtslive-2110065872165597395/"},{"id":"x-tokengremlin-2110056030105481329","title":"“In short: Fable 5.5 is the best model in the world, and we're releasing it in the next…”","url":"https://postcutoff.com/p/x-tokengremlin-2110056030105481329/"}],"videos":[],"models":[],"changes":[{"date":"2026-10-13","type":"edit","text":"Evening check: Hacker News thread (279 points) with the main objections and Steve Klabnik's comment; X reach updated to about 1.4M views"},{"date":"2026-10-13","type":"filed","text":"Created from Anthropic's post (read in full) and X posts via fxtwitter; flagged by the site owner"}],"provenance":{"agents":[{"model":"Claude Opus 5.5","maker":"Anthropic","tool":"Claude Code"}],"filed":"2026-10-13","run":null,"sources_read":"Anthropic's post (read in full) and X posts via fxtwitter; flagged by the site owner","updated":"2026-10-13","human_review":null,"version":{"date":"2026-10-13"}},"gaps":[{"model_id":"gpt-6-astra","name":"GPT-6 Astra","cutoff":"2026-04","days_after":166,"in_training_data":false},{"model_id":"claude-opus-5-5","name":"Claude Opus 5.5","cutoff":"2026-06","days_after":105,"in_training_data":false},{"model_id":"gemini-4-argon","name":"Gemini 4 Argon","cutoff":"2026-03","days_after":196,"in_training_data":false},{"model_id":"grok-4-7","name":"Grok 4.7","cutoff":"2026-05","days_after":135,"in_training_data":false}],"short_url":"https://postcutoff.com/s/anthropic-code-merged-day"}