The copyright argument is a sidetrack both in the PR comment thread and here. The issue opened claims the new code is based on the old code, and therefore derivative, and therefore must be offered in a modified version of the source code under the previous license, LGPL. The complaint is the maintainers violated the terms of LGPL, that they must prove no derivation from the original code to legally claim this is a legal new version without the LGPL license. Claim is if they or Claude read the old code (or of course directly use any of it) it is a license violation. “… in the release 7.0.0, the maintainers claim to have the right to “relicense” the project. They have no such right; doing so is an explicit violation of the LGPL. Licensed code, when modified, must be released under the same LGPL license. Their claim that it is a "complete rewrite" is irrelevant, since they had ample exposure to the originally licensed code (i.e. this is not a "clean room" implementation).“ By this reasoning, I am genuinely asking (I’m not a license expert) if a valid clean room rewrite is possible, because at a minimum you would need a spec describing all behavior, which ses to require ample exposure to the original to be sufficiently precise.