Exploring Claude's System Prompt Evolution with an Innovative Git Timeline

research#prompt engineering📝 Blog|Analyzed: Apr 18, 2026 23:34
Published: Apr 18, 2026 12:25
1 min read
Simon Willison

Analysis

Simon Willison has brilliantly transformed Anthropic's publicly available system prompts into a highly granular, version-controlled git repository. This innovative approach allows researchers to seamlessly navigate the history of Claude's underlying instructions using familiar developer tools. It is a fantastic resource that significantly enhances transparency and makes tracing the evolution of AI behavior incredibly accessible and engaging.
Reference / Citation
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"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."
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Simon WillisonApr 18, 2026 12:25
* Cited for critical analysis under Article 32.