macOS 27's unzip refuses to extract a symlink member whose target is absolute or escapes the destination and exits 2, so the volume label examples that archived such a symlink fail there before reaching the fallback they test. Plant the same-named symlink in unpack_dir instead so both examples keep guarding the move by basename and the symlink unlink on every macOS version. brew tests --only=unpack_strategy/zip on macOS 27 reproduces the failures.

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Claude Code (Opus 5.5) found the cause by running scratch ZIP fixtures through /usr/bin/unzip, ditto and a direct symlinkat call, then wrote the change. It checked that both examples fail on main and pass with the change, that they still fail when either protection in extend/os/mac/unpack_strategy/zip.rb is removed and that brew lgtm passes.