The Axiomatic Opacity Constraint: Epistemic Self-Limitation and the Architecture of Embedded Agency

The Axiomatic Opacity Constraint (AOC) states that no agent embedded in a causally closed system operating under linear temporal ordering can achieve infallible epistemic access to its own future states while retaining the capacity for causal intervention. Previously established as a corollary of the Fixed-Point Paradox, the AOC merits independent examination. We prove that the AOC is axiomatic in the strict sense: derivable from temporal linearity, informational closure, and non-contradiction alone, prior to any empirical commitments. We establish formal connections with Gödel incompleteness, Turing undecidability, and Lawvere's categorical fixed-point theorem, situating the AOC as a fourth member of the self-reference family. We derive the Probability Corollary: no contingent future event can receive credence one for any embedded agent retaining causal agency. We prove the Optimal Epistemic Position Theorem: deliberative efficiency DE = ρ·Ω (reason-responsiveness times residual epistemic uncertainty) is maximized at an interior noise level σ* = γσ_R, with maximum efficiency DE* = (1−φ²)/4. Neither certainty nor randomness is optimal; the wisest agent operates at the equipartition point. We extend the AOC to multi-agent systems, derive structural consequences for communication and moral assessment, and establish that the first-person perspectival asymmetry is a formally necessary feature of any agent retaining causal agency rather than a contingent limitation. The epistemology of perspective is not incidental to agency but constitutive of it.