V01.07 — Mirror Physics I: Constraint Propagation and the Physical Conditions for Observerhood

This paper is the first paper in the Physics Support Arc of the Mirror Programme, Volume I: Observerhood. It bridges the completed theory, mathematical and computational observerhood sequence into a conservative physical-support account of observer-continuity. Mirror Theory derives observerhood from constraint, viability, bounded modelling, self-modelling and recursive reliability tracking. Earlier work in Volume I formalised constraint regimes, minimal observer thresholds, recursive reliability, governed memory incorporation and identity-continuity. This paper asks what physical conditions must be present for such observers to be realised in a universe like ours. The paper does not propose a modification of special relativity, general relativity, quantum theory or thermodynamics. Instead, it identifies physical support conditions for recursive observer-continuity: ordered causal update, finite channels of propagation, locally persistent substrates, metastable memory, thermodynamic throughput and error-corrective repair. Within this framing, the invariant speed ccc is not redefined or exceeded; it is treated as part of the causal constraint structure that bounds physical update in relativistic spacetime. The central result is a causal support theorem: if a local system robustly maintains observer-continuity across time, then the underlying physical regime must support compatible structures of causal ordering, local persistence, memory preservation, viability-relevant interaction and correction under perturbation. The paper thereby provides a conservative bridge from Mirror mathematics to future physical work without claiming new physics.