Spec with pseudocode and test vectors, APK disassembly, analysis tools, shelved reference Python and the macOS BLE probe. Findings are not yet validated against a real tag. The vendor XAPK and nested lib clone are excluded. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EinWd3UT2Xw7UakFtTp6hn