Claude system prompts as a git timeline

Research: Claude system prompts as a git timeline Simon Willison’s Weblog Subscribe Sponsored by: Honeycomb — AI agents behave unpredictably. Get the context you need to debug what actually happened. Read the blog 18th April 2026 Research Claude system prompts as a git timeline — Anthropic's published system prompt history for Claude is transformed into a git-based exploration tool, breaking up the monolithic markdown source into granular files and timestamped commits. By structuring extracted prompts per model, family, and revision, researchers can leverage `git log`, `diff`, and `blame` to trace prompt evolution, compare differences, and attribute changes to specific dates—all without manual parsing. Anthropic publish the system prompts for Claude chat and make that page available as Markdown . I had Claude Code turn that page into separate files for each model and model family with fake git commit dates to enable browsing the changes via the GitHub commit view. I used this to write my own detailed notes on the changes between Opus 4.6 and 4.7 . Posted 18th April 2026 at 12:25 pm Recent articles Changes in the system prompt between Claude Opus 4.6 and 4.7 - 18th April 2026 Join us at PyCon US 2026 in Long Beach - we have new AI and security tracks this year - 17th April 2026 Qwen3.6-35B-A3B on my laptop drew me a better pelican than Claude Opus 4.7 - 16th April 2026 This is a beat by Simon Willison, posted on 18th April 2026 . ai 1967 generative-ai 1745 llms 1712 anthropic 272 claude 269 system-prompts 52 Monthly briefing Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments. Pay me to send you less! Sponsor & subscribe Disclosures Colophon © 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026