Unified Coherence Geometry: A Common Action for Physical Fields

This paper introduces a unified geometric formulation of Coherence Geometry for physical fields. It develops the Unified Coherence Action (UCA), a variational principle in which physical field equations are treated as domain-specific projections of a common coherence-geometric structure. The manuscript represents physical systems through continuous coherence fields with amplitude and multi-phase structure, and studies how constrained forms of the action project into familiar physical regimes, including classical mechanics, gravitation, electromagnetism, quantum systems, thermodynamic transport, hydrodynamic behavior, and relativistic field structure. Across these regimes, quantities such as energy, momentum, temperature, curvature, entropy, and quantization are interpreted through coherence transport, phase alignment, topological closure, and variational constraint. This record contains the original hash-committed foundation paper associated with Coherence Geometry Canon CDR-01. The PDF is released in the same form referenced by the CDR-01 provenance record so that the public file remains consistent with the recorded SHA-256 hash. Later documents may expand individual derivations, equivalent formulations, or domain-specific consequences, while this record preserves the original foundation statement.