This preprint presents "Observer-Patch Holography," a foundational model in which fundamental degrees of freedom reside on a spherical horizon screen S², and physical reality emerges from the mutual consistency of overlapping local descriptions (patches) associated with internal observers.There are some great places for learning OPH:- Via this notebook. Watch the introduction video, then ask the model any questions to dig deeper.- With the interactive lab on floatingpragma.io Supplements to this paper: Emergence of gravity, measurement problem, dark matter, Koide formula, baryogenesis, and other derivations/proofs Recovering string theory from OPH Particle spectrum predictions See also: Book for non-Physicists Blog Post: How OPH solves the hardest open Physics problems Github repository The OPH framework is built on minimal axioms: - A net of von Neumann algebras assigned to connected subregions of S² with isotony and overlap consistency- Local Markov/recoverability conditions on separators (with controlled error in refinement limits)- Maximum-entropy state selection under rotationally invariant constraints Under these assumptions — together with derived properties such as edge-center completion from gauge-as-gluing, geometric modular covariance on caps, and null-surface modular additivity — the model yields: - Lorentz kinematics from geometric modular flow on caps (Bisognano-Wichmann on S²)- Semiclassical Einstein equations via entanglement equilibrium and a derived EFT bridge on null surfaces- Compact gauge symmetry reconstructed from edge-sector fusion via Tannaka-Krein duality- Masslessness of gauge bosons and the graviton as symmetry-protected zeros from emergent invariance The approach is explicitly holographic: all bulk physics arises from 2D boundary data and patch-overlap consistency, with "gluing freedom" naturally producing gauge structure. String theory emerges as a natural effective description at intermediate scales due to shared conformal symmetry (Conf(S²) ≅ SO(3,1)). Additional features include a prediction of the Higgs mass within 1σ of the experimental value and a resolution of foundational questions by eliminating any objective "third-party" or "God's eye" perspective. This work is presented as a candidate framework unifying quantum gravity, gauge theory, and observer-dependent emergence. It is released publicly for scrutiny and further development.