This paper studies the upper gate of VBRC, also called the Planck-label gate, as a gate-scoped R3 time completion of the protocol-licensed summary-side quotient. It is not a direct opening of raw unread interior data, not a numerical claim about physical Planck-scale ontology, and not a new structural law-space. Under the Internal Invisibility Principle, raw unread content never enters retained laws. The upper gate instead applies conservative time completion to the retained channel and to a gauge-fixed representative of the summary-side quotient inherited from Part I. The upper gate is read within the low-energy atlas fixed in Part XV. Unlike the quasistatic summary window of Part XV or the memory-dependent mixed gate of Part XVI, Part XVII studies the window in which the licensed summary is itself time-completed. Starting from a minimal coupled action on the inherited branch, the paper derives the coupled representative-level equations and eliminates the time-completed summary-quotient representative. The resulting retained closure is governed by the same reduced Schur structure as the earlier low-energy representative, now evaluated on the upper-gate-completed summary-side window. The principal outputs are quartic dispersion, genuine two-branch spectral splitting, and a critical threshold for the stability of the licensed summary-quotient completion. Plane-wave analysis gives a critical wave number controlled by the normalized coupling ratio. At the mode level, the instability is equivalently the loss of positive definiteness of the coupled stiffness matrix on the corresponding nonzero window. The lower branch also selects a fastest-growing scale within the symbolic linearized analysis. The interpretation is conditional and gate-scoped. The lower-branch instability signals that the fully time-completed summary-quotient window cannot persist as the stable readable low-energy regime and must reorganize toward a reduced phase in which the summary is again read on a quasistatic or frozen window. The resulting Schur residue is not a universal mass term. It is a channel-selective retained residue of the post-instability reduced branch. Thus mass is not the primary content of the upper gate; it is a possible residue of the stable phase reached after gate handoff. Part XVII therefore continues the threshold grammar of Parts XV and XVI at one gate higher, while leaving the saturation and frozen-handoff mechanism as conditional post-instability structure.
Yi (Fri,) studied this question.