MIsCORE–RIUD: Paper VI Frequency, Timing, Geometry, and the Mechanism Boundary

Paper VI tests whether the already-frozen MIsCORE–RIUD merger dynamics can be reduced to a simpler predictive or microscopic description without rebuilding the lower-order observational system. The predictive arm finds a strong frequency phenotype but no independent out-of-fold predictive law, and geometry provides no incremental support. The mechanistic arm tests direct GR waveform representations, richer source-state and history variables, orbital/spin structure, source-native SXS dynamics, common-horizon relaxation, QNM chronology, RAW carriers, timing, and source-variable reduction. The higher-order path structure survives multiscale SXS replay, and a measurable common-horizon-to-QNM relaxation chronology is present, but no unique microscopic derivation of the frozen R40 transition system is established. The PRE/POST operator reorganizes strongly across intrinsic progression, while R40 remains a rate law on normalized progression rather than an absolute-seconds clock. A 20-variable, 9,999-permutation family-corrected source screen identifies CHI_A_NORMALIZED as the strongest surviving source association (MaxT p = 0.0321) without refitting the frozen law. Paper VI therefore closes the reduction campaign at a defined boundary: the effective state/history dynamics survive simple predictive and microscopic compression, while the viable source-mechanism space is narrowed without being reduced to a unique first-principles explanation. No GR violation, new-physics detection, exact physical MT identity, absolute-second R40 clock, or unique microscopic mechanism is claimed. Holdout30 remains unopened. Related integrated volumehttps://zenodo.org/records/22254049 Standalone Papers MIsCORE–RIUD: Paper IDefining and Falsifying Recurrent Merger-Local Morphology in Gravitational-Wave Post-Model Data* https://zenodo.org/records/22319453 MIsCORE–RIUD: Paper II Connected Multiscale Paths in Gravitational-Wave Post-Model Data* https://zenodo.org/records/22278310 MIsCORE–RIUD: Paper III Partially Shared Dynamics in Recurrent Gravitational-Wave Undiscovered Pathshttps://zenodo.org/records/22282910 MIsCORE–RIUD: Paper IV Population Dynamics and a Frozen Physical Clockhttps://zenodo.org/records/22313433 MIsCORE–RIUD: Paper V Cross-Representation Regimes and Physical Sectors in Black-Hole Merger Dynamicshttps://zenodo.org/records/22332074 MIsCORE–RIUD: Paper VIFrequency, Timing, Geometry, and the Mechanism Boundary https://zenodo.org/records/22409081