Gravitational Phenomena as Emergent Properties of Observable Algebra Selection: A Structural Analysis

Can physical histories select a localization structure whose evolution is gravitational, rather than merely alter an observer's reconstruction? We develop this proposal through three demands: the selected structure must admit a common geometric consistency law, the selecting interaction must carry the complete physical source, and its response must enter later operations. A conformal scalar bridge fixes the first-order sourced Einstein tensor from common stress and surface data, exposing why a change of algebra at fixed matter history is not an additional source. Actual correction, protection and projection interactions do change stress. A finite scalar/JT mean-action model connects an acquired record to material radiation and a later acquisition while retaining the old content, references, clock, support and work. Maintenance adds a selection pressure: pointer alignment lowers the complete renewal debit, and a thermal chiral exhaust of fixed capacity has a quadratic entropy-rate price. Sustained renewal and joint sharp exhaust with nonvanishing causal return remain strong targets. Their window, delay and resource conditions identify what must be realized together. The common-action conjecture asks more than ordinary feedback in an assigned gravity theory: the same dynamics must form the localization structure and explain its geometric law. Main and Appendices PDFs are supplied separately, with full sources and scientific supplements in the accompanying ZIP.