--- title: Anthropic's Scion is heavily inspired by Mononoke description: The creator of Facebook's Mononoke source control server points out that Anthropic's newly announced version control system, Scion, closely mirrors Mononoke's... canonical: https://daily.dev/posts/anthropic-s-scion-is-heavily-inspired-by-mononoke-cjgzwv5qx twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Anthropic's Scion is heavily inspired by Mononoke | daily.dev og:description: The creator of Facebook's Mononoke source control server points out that Anthropic's newly announced version control system, Scion, closely mirrors Mononoke's... og:url: https://daily.dev/posts/anthropic-s-scion-is-heavily-inspired-by-mononoke-cjgzwv5qx og:image: https://api.daily.dev/og/posts/CJGzwv5qx.png og:image:alt: Anthropic's Scion is heavily inspired by Mononoke og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Anthropic's Scion is heavily inspired by Mononoke **[Hacker News](https://daily.dev/sources/hn)** · 2 min read · 0 upvotes · 0 comments ## Summary The creator of Facebook's Mononoke source control server points out that Anthropic's newly announced version control system, Scion, closely mirrors Mononoke's architecture — specifically its use of 'derived data' to speed up operations like blame. The author, who worked on Mononoke and described this same concept in materials from 2022, says the imitation goes beyond shared insight, contrasting it with Cursor's Vicent Marti blog post on git scaling, which has similar goals but different design choices. The author has no issue with the design being copied since Mononoke is open source, but argues that as LLMs trained on open-source code increasingly influence new system designs, giving credit to prior art is both easier and more important than ever — noting that asking Claude Opus or GPT models about prior art immediately surfaces the Mononoke connection. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is the 'derived data' concept used in Mononoke and Anthropic's Scion version control system? Derived data is a design concept where expensive-to-compute information, such as blame history, is precomputed and cached separately from the raw version control data, making operations like blames much more efficient. Mononoke, the source control server built for Facebook, used this concept as early as 2017-18, and Anthropic's new system Scion reportedly uses a nearly identical approach. _Developers evaluating new version control architectures can follow design debates like this one on daily.dev._ ### Is Anthropic's Scion version control system based on Mononoke's design? Scion's described use of 'derived data' for efficient operations like blame closely parallels Mononoke's 2017-18 design, according to one of Mononoke's original builders, who argues the similarity goes well beyond coincidental shared insight. The claim is partly based on asking Claude Opus 5.5 and GPT-6 Astra about prior art, both of which immediately identified Mononoke as the precedent. _Anyone comparing version control systems and their lineage can track these design disputes on daily.dev._ ## Community take How the wider developer community reacted, aggregated from 2 discussions and 119 comments across hackernews, lobsters (as of 2026-10-15). **TL;DR:** Discussion centers on whether Anthropic adequately credited Mononoke/Sapling in its Scion announcement, with many arguing the data model is a near-direct copy deserving explicit attribution, while others see the Sapling mention as sufficient and the complaint overblown. **Sentiment:** 15% positive · 35% mixed · 50% skeptical **The case for** - Several note Anthropic did credit Sapling (which includes Mononoke) and link to its repo, so the complaint may be overstated. - Some argue building new VCS infrastructure makes sense given real scaling pain points that Google, Meta, and GitHub have also hit. - A few see AI-assisted engineers simply reproducing institutional knowledge from prior FAANG work as normal and expected. **The pushback** - Many argue the data model and terminology are a near-direct copy of Mononoke, not just 'inspiration,' and deserve explicit credit. - Some suspect the announcement is IPO-oriented marketing, hyping novelty that isn't really new. - Concern that LLM-assisted design increasingly launders provenance, making it look like ideas emerged de novo when they didn't. - Doubts raised about whether the stated scale/PR-volume justification for a new VCS is even meaningful or verifiable. - Some question why contributor names were abbreviated to initials, suggesting possible obscuring of Meta/Google overlap. **By community** - hackernews (heated): Long, contentious back-and-forth between the original author defending the attribution complaint and others (including a prominent commenter) arguing the Sapling credit was sufficient, with side debates about IPO marketing and AI's role in design. - lobsters (heated): A sharp, repeated clash between the post's author insisting credit was inadequate (even alleging bad faith) and a commenter defending Anthropic's engineering choices as reasonable. **Hottest debate:** Whether crediting 'Sapling' was sufficient attribution or whether Mononoke specifically needed to be named given how closely its data model was replicated. **Open questions** - Was the similarity to Mononoke the result of direct knowledge from overlapping contributors, or simply AI models drawing on training data? - Did Anthropic act in bad faith, as one commenter claims to have been privately told, and what evidence supports that? - How different is Mononoke really from Google's Piper, and could comparative analysis clarify the originality question? **Highlights** > From my post: > And, to be clear, I do not have a problem with Anthropic copying Mononoke’s design. (This is part of why we put out open source — to benefit humanity through the spread of good ideas.) > But as LLMs continue to assist in designing new systems, they are likely to index heavily on existing designs. Mononoke is open source and in every LLM’s training set. If you ask Opus 5.5 or GPT-6 Astra (thanks Matthew Fowle) about prior art, they both immediately point out the similarities to Mononoke. > Giving credit to those that came before us is now easier — and more important — than ever. There is no longer an excuse. > — [sunshowers on hackernews · 1 comments](https://news.ycombinator.com/item?id=50095847) > Oh, is that why they only listed the initials of the contributors in their blog post? The plot thickens! > — [mycoliza on hackernews · 1 comments](https://news.ycombinator.com/item?id=50096987) > I have since privately received information that this was done in bad faith, and that I was far too generous in my post. Does that change your beliefs? > — [sunshowers on lobsters · 1 points, 2 comments](https://lobste.rs/s/plcgps/anthropic_s_scion_is_heavily_inspired_by#c_wtwktk) > Rebuilding what you know from the previous FAANG you worked at is expected on the whole. What is douchey is presenting the whole thing as some sort of intense novelty and stroke of genius required in the age of agents when it's just doing what the other BigCo companies did to scale their monorepos already. Like a decade ago. The reality it is when I first read the thing I was -- as a Xoogler -- like "Oh, yeah, so, like Piper & SrcFs and the stuff that Meta also does" and really didn't understand why they wouldn't have started with something off the shelf inside of vibe-conjuring a clone that they would then have to support To me it speaks ill, again, of the engineering culture at Anthropic. "We do these things not because they are useful, but because they are novel." Don't they have better things to do at Anthropic than building their own source control or rewriting Bun from scratch in another language? Like, y'know, basic site reliability? Or a coding harness that doesn't eat multiple GB of RAM? > — [cmrdporcupine on hackernews · 1 comments](https://news.ycombinator.com/item?id=50097406) > If I credit my newly introduced car as inspired by Corvette, then sure, it might be ok not to mention the engine (Mononoke is the server part of Sapling) However if my new car's engine is a near copy of the one in the Corvette, and my announcement gushes about the engine using the same terms the Corvette design team invented... Then can you see how a mention might be nice? > — [WhitneyLand on hackernews · 1 comments](https://news.ycombinator.com/item?id=50096179) **Source threads** - [hackernews](https://news.ycombinator.com/item?id=50094694) · 217 points · 103 comments - [lobsters](https://lobste.rs/s/plcgps/anthropic_s_scion_is_heavily_inspired_by) · 39 points · 16 comments ## Similar posts on daily.dev - [Google Open Sources Experimental Multi-Agent Orchestration Testbed Scion](https://daily.dev/posts/google-open-sources-experimental-multi-agent-orchestration-testbed-scion-lnrn47ksh) · InfoQ · 0 upvotes · 0 comments - [Google’s Scion Gives Developers a Smarter Way to Run AI Agents in Parallel](https://daily.dev/posts/google-s-scion-gives-developers-a-smarter-way-to-run-ai-agents-in-parallel-os7hdmwvq) · DevOps.com · 0 upvotes · 0 comments - [Anthropic’s rough week: leaked models, exposed source code, and a botched GitHub takedown](https://daily.dev/posts/anthropic-s-rough-week-leaked-models-exposed-source-code-and-a-botched-github-takedown-m7takp1vp) · The New Stack · 0 upvotes · 0 comments --- Tags: [#open-source](https://daily.dev/tags/open-source), [#anthropic](https://daily.dev/tags/anthropic), [#version-control](https://daily.dev/tags/version-control) [View this post on daily.dev](https://daily.dev/posts/anthropic-s-scion-is-heavily-inspired-by-mononoke-cjgzwv5qx) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Anthropic's Scion is heavily inspired by Mononoke","url":"https://daily.dev/posts/anthropic-s-scion-is-heavily-inspired-by-mononoke-cjgzwv5qx","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/anthropic-s-scion-is-heavily-inspired-by-mononoke-cjgzwv5qx"},"datePublished":"2026-10-14T21:39:11.997Z","dateModified":"2026-10-15T00:25:19.915Z","description":"The creator of Facebook's Mononoke source control server points out that Anthropic's newly announced version control system, Scion, closely mirrors Mononoke's...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/43c2053bd49b9aac7556d590a7bc29f0?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/43c2053bd49b9aac7556d590a7bc29f0?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Hacker News","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Hacker News","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/hn","url":"https://daily.dev/sources/hn"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/anthropic-s-scion-is-heavily-inspired-by-mononoke-cjgzwv5qx","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"open-source,anthropic,version-control","timeRequired":"PT2M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Hacker News","item":"https://daily.dev/sources/hn"},{"@type":"ListItem","position":3,"name":"Anthropic's Scion is heavily inspired by Mononoke"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/anthropic-s-scion-is-heavily-inspired-by-mononoke-cjgzwv5qx#faq","mainEntity":[{"@type":"Question","name":"What is the 'derived data' concept used in Mononoke and Anthropic's Scion version control system?","acceptedAnswer":{"@type":"Answer","text":"Derived data is a design concept where expensive-to-compute information, such as blame history, is precomputed and cached separately from the raw version control data, making operations like blames much more efficient. 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