Changes in the system prompt between Claude Opus 4.6 and 4.7

Changes in the system prompt between Claude Opus 4.6 and 4.7 18th April 2026 Anthropic are the only major AI lab to publish the system prompts for their user-facing chat systems. Their system prompt archive now dates all the way back to Claude 3 in July 2024 and it’s always interesting to see how the system prompt evolves as they publish new models. Opus 4.7 shipped the other day (April 16, 2026) with a Claude.ai system prompt update since Opus 4.6 (February 5, 2026). I had Claude Code take the Markdown version of their system prompts, break that up into separate documents for each of the models and then construct a Git history of those files over time with fake commit dates representing the publication dates of each updated prompt—here’s the prompt I used with Claude Code for the web.…