Why Decoherence Cannot Replace Measurement: Outcome-Resolved Dynamics Without a Fundamental Measurement Postulate in Modal Triplet Theory

Version 2. Measurement is treated as an ordinary system-apparatus-environment process with a retained record, not as a fundamental observer act. The paper proves in finite-dimensional quantum theory that pointer dephasing is a nonselective completely positive trace-preserving channel and that the same channel can arise from distinct outcome instruments with different probability laws. Consequently, decoherence alone specifies neither recorded outcomes nor their probabilities, and an MTT basin boundary or chart exit does not select a successor basin. A complete outcome-resolved model requires an instrument or normalized continuation kernel and its source. Current tier. The canonical q79 binary recorder supplies an exact stopped-output law on its declared finite domain; general apparatus contexts and objective single-history actualization remain open.