Mastodawn

The chardet open source library relicensed from LGPL to MIT two days ago thanks to a Claude Code assisted "clean room" rewrite - but original author Mark Pilgrim is disputing that the way this was done justifies the change in license - my notes here: https://simonwillison.net/2026/Mar/5/chardet/

Can coding agents relicense open source through a “clean room” implementation of code?

Over the past few months it’s become clear that coding agents are extraordinarily good at building a weird version of a “clean room” implementation of code. The most famous version …

Simon Willison’s Weblog

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Tom Insam

@simon im so intrigued by the position (taken by a few of the commenters there) of “this would be ok with a different name” which seems to imply that there isn’t a copyright issue at all (otherwise it would not be fine) but that the license is somehow attached to the package name and not the implementation.

Dan clearly has the right to release software with that name - he’s the maintainer - and in the eyes of some he’s also allowed to produce a clean-room implementation, but he’s not allowed to release that implementation with the other name?

I see the position but it seems very narrow.