The SIP-PHY Forks Register, v2.1 A consolidated register of eight registered foundational forks — well-formed open questions, each with named branches, traced consequences, and resolution criteria — in the quantum-foundations layer of the GTRS / coherence–decoherence–recoherence (CDR) framework. A registered fork turns a hidden theoretical tension into transparent research infrastructure; the register records what is open and why, and asserts no resolutions. A working connection map (explicitly a hypothesis for examination, not established structure) proposes that the eight forks may cluster around two deeper roots — an orientability question on the state manifold and an observer/selection question. Version 2.1 propagates the decidability finding of SIP-PHY-NOTE-04 (24 May 2026) into the topological branch of FORK-02, FORK-04, and FORK-06, and sharpens §3.1 accordingly. The topological reading of the "Klein cluster" is reclassified from open, attack via the toy model to open, but untestable on the single-oscillator model — a statement about the reach of the instrument, not a refutation — with the decisive test relocated to a holonomy check on a parameter manifold. No fork is closed and no new physics is introduced; the change is record-keeping. All eight forks remain open. Part of the SIP corpus, SymbioMind Research Practice. Released under CC BY-NC-SA 4.0 as a pedagogical boundary: use to teach, not to certify.
Smith et al. (Mon,) studied this question.