The Modal Triplet Theory Program A1: Coherent Kinematics

We develop a kinematic framework for Modal Triplet Theory that does not presuppose spacetime, geometry, or equations of motion. Motion is defined as persistence of coherent structure across chains of overlapping admissible encodings, and worldlines are identified as equivalence classes of admissible continuation chains under re-encoding. Using only the structural core of MTT, we derive causal structure, horizons, selection fronts, termination of motion, and irreversibility as unavoidable consequences of finite admissibility and global obstruction. Null and timelike distinctions arise from admissible continuation properties rather than from a metric. The results provide a purely structural notion of kinematics that underlies later emergence of gravity, gauge structure, and quantization as encoding responses.