A Code Authorship Analysis on the Claude Code Leak. What Was Found Doesn't Match Human or AI Code.

On March 31, 2026, Anthropic shipped a source map in their npm package, exposing 514,000 lines of TypeScript. Thousands of developers analyzed it. They found feature flags, a pet system, undercover mode, and a frustration regex. Nobody analyzed the authorship pattern of the code itself. Curia is an evidence-accumulating prediction system built for unrelated research. It turned out to be exactly the right tool to ask a question nobody was asking: does this code look like it was written by humans? The numbers are real. What they mean is up to you. The Fingerprint 30+ metrics were extracted from every TypeScript file and compared across codebases spanning two eras: Codebase Era Purpose Next.js v12.0.0 2021 Pre-AI baseline Next.js latest 2026 Same project, AI era TypeORM 0.2.29 2020 Pre-AI baseline TypeORM latest 2026 Same project, AI era Vite 1.0-rc13 2020 Pre-AI baseline Vite latest 2026 Same project, AI era Claude Code Action 2026 Same Anthropic team, same project type Claude Code v2.1.