If uv/pip exits with code 0 but emits non-JSON output (e.g. warnings that slip through -qqq), json.loads in _run_pip_dry_run raises json.JSONDecodeError, which is not caught by except DryRunFailed here and will crash the entire script instead of skipping that python version gracefully. Have you considered widening the except clause to also catch json.JSONDecodeError (and possibly KeyError)?

At line 732 (_has_free_threading_dependencies), wheel_filename.rstrip(".tar.gz") removes any character from the set {'.','t','a','r','g','z'} from the right — not the literal suffix .tar.gz. For a sdist like foo-2.0a.tar.gz it would strip the trailing a from the version, corrupting the package name/version split. Use removesuffix(".tar.gz") (already used correctly at line 700 for .whl).