Information Protection as a Fundamental Principle I: Classical Foundations -- Inertia, MOND, and Dark Energy from Information-Response Dynamics

We present the classical foundations of a unified framework in which inertia, gravitation, the dark matter phenomenon, and the cosmological constant emerge from a single underlying principle: spacetime acts to protect the information content of physical systems from arbitrary modification. Starting from a single foundational axiom, we derive the equivalence of inertial and gravitational mass, a finite-difference response equation for acceleration, and a natural transition to Modified Newtonian Dynamics (MOND) in the low-acceleration regime. Crucially, the MOND interpolation function mu (x) = x / sqrt (1 + x²) is derived without any free parameters from a strictly independent combination of the holographic entropy bound and the Rindler--de Sitter temperature. The characteristic MOND acceleration scale a0 is shown to be exactly c² sqrt (Lambda / 3), linking galactic dynamics directly to the cosmological constant. We construct a covariant vector-tensor action that encodes the information-response lag via a dynamical preferred frame, and we demonstrate that the theory reduces to general relativity in high-acceleration environments, to MOND on galactic scales, and to a holographically natural dark energy component on cosmological scales. Testable predictions include a quantifiable violation of the equivalence principle at accelerations below a0, a tight correlation between a0 and Lambda, and specific modifications to the growth of cosmic structure. The framework offers a conceptually unified, zero-parameter resolution to the dark sector puzzles and provides a new information-theoretic foundation for gravitational physics.