Anthropic’s newly released version‑control system, Scion, adopts the “derived data” technique originally pioneered in the Mononoke source‑control server to accelerate operations such as blame calculations. Both systems store auxiliary, pre‑computed views of the repository that enable fast retrieval of line‑origin information without scanning the full history. The author of the Mononoke project notes that Scion’s description mirrors the 2022 Oxide candidate materials that detailed how Mononoke used derived data to achieve comparable performance gains, suggesting a level of imitation that extends beyond superficial similarity. While Anthropic acknowledges Sapling for “hard‑won lessons,” it omits any mention of Mononoke, a omission the author characterizes as bordering on plagiarism given the near‑identical core insight. The post also references prior art examined during Mononoke’s development, including Google’s SrcFS and database‑style write‑ahead logs, and observes that contemporary large language models such as Opus 5.5 and GPT‑6 Astra readily identify the overlap when asked about relevant prior work. Finally, the author points to Vicent Marti’s Cursor blog post as an example of a system that shares the derived‑data insight but diverges in key design choices.