rederive is live: verify what a package does, not who published it
The infrastructure behind Friday's essay. The registry hands you bytes and a name to trust; rederive ships the contract instead — a spec and a held-out oracle the publisher can't move. Plus three things you can run right now.
Your tests pass. Would they notice if the code was wrong?
97% line coverage, a green suite, millions of weekly downloads — and a real bug none of it could see. What characterization testing finds that coverage misses.
Modernize legacy code without changing what it does
A 2,000-line module, no tests, nobody left who understands it. Keep the original running as the oracle, refactor into clean units, and prove the behavior is unchanged.
Verifying code that has no reference
When there's no original to execute, where does the oracle come from? Property oracles, decompose-to-named-leaves, and the discipline of sourcing truth for brand-new code.
The contract underneath it all
SIR: a language-neutral behavioral contract that lets a JavaScript function be re-derived in Rust and proven identical. The format, the invariants, and why the oracle is the substrate.
Vibe coding, minus the vibes
The essay that opened the week. An AI wrote this Rust; a reviewer called it gorgeous. Vibe is uncertainty made visible — remove the freedom and the slop disappears.
colors.js had a trusted maintainer. That was the problem.
Every supply-chain defense we've built verifies the pipeline. None of it verifies the payload. What a held-out oracle catches that provenance can't.