Anthropic's release-notes page lists the system prompt shipped with every Claude model since Claude Haiku 3, with diffs bolded where a prompt changed between dated versions for the same model. A submission by user tosh reached 331 points…
In the News: August 16, 2026, Evening
A Hacker News thread on Anthropic's system-prompt diffs shows what's baked into Claude's harness, and Simon Willison's case for why it stays closed to users.
Evening edition
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