Simon Willison’s Weblog

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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.

This is a beat by Simon Willison, posted on 18th April 2026.

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