A developer cloned Photoshop with Claude. Is that legal?

A commit called "one-shot"

On September 30, around 11 a.m. Paris time, Brandon Thomas records a commit titled "one-shot": 42,241 lines in one go, less than three hours after the project's first commit. Overnight between October 1 and 2, he posts on Hacker News: "Software is over." Then: "I just one-shotted Photoshop. The whole thing."

The project is called ArtCraft, and its flagship, PhotoCraft, bills itself as a clean-room reimplementation of Photoshop. Three questions follow: how did he do it, is it legal, and what does it mean for Adobe. So we opened the repo.

What the repo shows

ArtCraft starts as seven free apps under MIT or Apache licenses: stand-ins for Photoshop, Illustrator, Premiere, Lightroom, After Effects, InDesign and Acrobat, written in Rust for Mac, Windows, Linux and the browser. On October 7, the organization added clones of Word, Excel, PowerPoint, AutoCAD and Pro Tools.

On October 13, PhotoCraft had 55,400 GitHub stars. Thomas's stated motive, on Hacker News: he'd been burned by Adobe's cancellation fees once too often.

The "one-shot" was only the first floor. As of October 10, the contributors file lists 1,302 commits and 189 contributors. Claude Opus 5.5, Anthropic's model, is co-author on 736 of them. That's countable because those commits carry a co-author trailer. The rest comes from Thomas, outside contributors and other models. Less a stroke of genius than a building site where the workers are agents and the foreman is a human.

The method is written down in the guidelines file that contributors and agents both read. The goal is "1:1 Photoshop parity": same menus, same shortcuts, same behavior. The rule is that Photoshop was studied for behavior and look only, its code is never copied, and everything is built from public specifications (Adobe's documented PSD format, the ICC color standards) and observation. Every function can also be driven by an agent.

The observation is serious. The team installed Photoshop 2026 and inventoried the package without launching it: default shortcuts, plug-ins, strings from the main binary. A companion repo holds more than 250 PSD files generated by scripts that drive the real Photoshop. Each file embeds Photoshop's own rendering, and the tests check that PhotoCraft reproduces the same pixels. For one undocumented parameter, the team writes that it read the name in the software's internal strings.

A clean room with one room

The clean room has a history. In 1984, Phoenix Technologies wanted to sell an IBM-compatible BIOS without copying a line of IBM's code. Engineers read the code printed in IBM's technical manual and wrote a specification. A different engineer, who had never seen that code, wrote the program from the specification alone. Phoenix kept a record of their exchanges.

That wall isn't, strictly speaking, a legal requirement. Legal scholar Andres Guadamuz, on his TechnoLlama blog, says it's "mostly about evidence": to infringe, you have to have copied, and the wall shows the people writing never had the original in front of them. Think of an alibi. You don't prove you did nothing; you prove you couldn't have.

ArtCraft's setup is different. Photoshop's source code isn't public, and nobody claims to have read it. But the repo's guidelines don't describe any partition between the people who observe the original and the people who write the code. That's exactly where Guadamuz locates the problem: there would be an issue, he writes, if the clean room is just the same developer who observes Adobe's software, writes the specifications, and then prompts the model to write the code. And one question can't be checked from the outside: what the model read during training.

What case law says

On copyright alone, the ground is fairly favorable. In Europe, the EU Court of Justice ruled in 2012, in SAS Institute v. World Programming, that neither a program's functionality, nor its programming language, nor its data file format is protected. A licensee can observe, study and test the software to understand its principles, and a contract clause saying otherwise is void. The same ruling warns that copying the manual can be infringement.

In the US, the Ninth Circuit held in 1992 (Sega v. Accolade) and again in 2000 (Sony v. Connectix) that copying or disassembling a program during reverse engineering, to reach its unprotected elements, is fair use. In 2021, the Supreme Court sided with Google against Oracle over roughly 11,500 lines taken from Java's programming interface. With a caveat people tend to forget: the Court assumed, without deciding, that the code was protected, and then found fair use.

The risk is elsewhere

Adobe's terms of use, in force since October 2025, forbid recreating its products. They specifically name monitoring or tracking an application's inputs and outputs "in order to recreate that system". We don't know under which license the project's copy of Photoshop runs, and in Europe the SAS ruling limits what a contract can forbid. Guadamuz, who says "very tentatively" that ArtCraft "may be" on the right side of the law in the US, puts the weak points outside copyright: licence terms, patents and trademarks.

Then there's the look. The README says "Familiar by design" and "If you know Photoshop, you already know PhotoCraft", and the interface guide describes a Photoshop-style theme. Ars Technica sees a "trade dress" risk. Add patents, which Adobe holds by the thousands according to PetaPixel, and product names suggestive enough, in Guadamuz's words, that one suspects a trademark lawyer is quietly making notes. As of October 13, we found no public action by Adobe, and no takedown notice against the project in the registry GitHub publishes.

45%, by the project's own count

On Reddit, according to Ars Technica and PetaPixel, Thomas promised full parity within a month. We couldn't open those posts ourselves. On October 5, on Hacker News, his tone was softer: 99% would be a matter of months, not years.

The project keeps its own books. As of October 10, it puts itself at roughly 45% of what a professional would need to replace Photoshop, with 579 open issues and 1,100 to 1,800 agent-hours of work before a beta. The README says it isn't yet a tool for daily work: generative AI, fifteen tools and plug-in compatibility are missing.

That's where the real shift sits. In under two weeks, all 631 menu entries found in Photoshop were wired into PhotoCraft: reproducing a program's surface now costs next to nothing. What Adobe sells to professionals lives in the other half: files exchanged without surprises, plug-ins, Firefly and support.

Open source already knows what a flood of AI-generated code costs to maintain. The copy has become cheap. The finished product hasn't.