CMS/CERN Quark Null Result under B_U: Candidate Residuals, Settlement Windows, and the Next Structural Boundary reclassifies the recent CMS search for quark substructure as a boundary-level result rather than a low-value null outcome. Based on Run 2 dijet angular distribution analysis, no significant deviation from the Standard Model was observed at the current 10^{-20}\,\mathrm{m} probing scale. Under B_U, this result is interpreted as evidence that candidate residuals for quark compositeness, extra dimensions, or related beyond-Standard-Model structures have not yet entered a readable, auditable, indexable, and settleable window. The paper distinguishes absence of detection from absence of structure: a null result means the candidate residual remains within the microscopic-zeroing interval and has not acquired settlement standing at the current resolution. It then derives the next natural structural settlement window through the inverse energy–length mapping, moving from E_{\mathrm{current}}\sim10^4\,\mathrm{GeV} and \lambda_{\mathrm{current}}\sim10^{-20}\,\mathrm{m} toward E_{\mathrm{ontic}}\sim10^{19}\,\mathrm{GeV}, yielding \lambda_{\mathrm{next}}\sim10^{-35}\,\mathrm{m}. The paper further separates geometric scale estimation from cost bridging, residual gating, readout probability, and auditability strength. Its central claim is that frontier null results should be treated as boundary imaging, candidate pruning, and settlement-window localization, not as empty experimental failure.