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Formally verifying the Claude Agent SDK

Research made with Claude Opus 5.5 · by Boris Cherny

Preview of “Formally verifying the Claude Agent SDK” by Boris Cherny
Still from media the creator shared publicly.

A couple of short prompts had Opus 5.5 model the Claude Agent SDK in Lean, leading to 16 pull requests that fixed bugs and race conditions. The creator says he doesn’t know Lean or TLA+ well.

Sources & verification

Verified against the original source on 11 Nov 2026.

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