Time as Actualization: A foundational ontology reconciling the quantum future and the relativistic past

Quantum mechanics describes the potential future; general relativity describes the actualized past; the present is the process of actualization that turns the one into the other. That single move is Time–Actualization (TA), the foundational ontology set out here. TA assumes the quantum formalism and the relativistic causal structure, and derives neither: it adds no new physics, makes no new prediction, and asks to be judged on coherence and unifying power rather than on a measurement. It proposes a common ontological reading of measurement, EPR and the structural arrow of time. D5 locates the einselecting environment in the event's causal past; the couplings within that past remain imported, and the system/environment split is relocated rather than removed. In detail. The ontology is a minimal triplet (ρ, ν, ⟨P,≺⟩): a positive normalized state ρ on a local net of algebras (the conditional future potential), a primitive tempo ν (the rate of becoming), and a growing causal set ⟨P,≺⟩ (the past). What is not derived, and is named as such throughout, is the Born rule, Einstein's equations, and the constants. Eight core hypotheses yield seven consequences. A structural arrow of time, prior to thermodynamics (D1). A partial dissolution of the measurement problem (D2), with definiteness posited and the trigger open. Conditional dissolutions of EPR and the signalling worry (D3–D4), requiring a propagation law. A preferred basis anchored in the couplings carried by the causal past (D5). A conditional thermodynamic reading of the structural arrow (D6), requiring a posited bridge to physical reset, and further thermal assumptions for its value. And a conditional coherence lemma (D7): the actualization dynamics is generally covariant and no-signalling once the substrate carries the standard locality of physics. D7 claims less than the Rideout–Sorkin Bell causality condition, which is a screening-off analogue of Bell's local causality and is not inherited. We then develop the proposed physics of the tempo ν: a correspondence with a local quantum speed scale and a saturation choice, both posited. Quantum speed limits alone do not bound an ontic event count. The missing bridge must specify event resolution, additive counting and an applicable composable speed bound. The substrate cadence that reconstructs proper time is kept distinct from a system's tempo; their operational connection remains to be supplied. TA aims at empirical equivalence to quantum mechanics on a causal-set substrate. We label the admissibility requirement P5; its verification, including instrumented multi-time statistics, remains open. No distinctive prediction is claimed. The causal-set "swerve" is inherited from discreteness, generic and not specific to actualization. We close with the open dynamics, its system/substrate interface, the conditional constitution of systems, and the inherited limits of the programme.