No Dice: The Double-Slit Is Deterministic - Quantum Probability Is a Discrete Preimage Count

One axiom. One operation. Zero free parameters. For a century quantum mechanics has been read as irreducibly random — God plays dice. This paper gives the fold’s reading of the double-slit, and there are no dice in it. The interference pattern is deterministic: where two fold paths arrive opposed they cancel to the One and the spot is forbidden (a dark band); where aligned they survive (a bright band), and the bands fall on a discrete standing-mode comb — the fold’s stationary states. What the textbook calls probability is a discrete preimage count (the atomic branch weight 1/8), not a continuum likelihood. The single-shot appearance of randomness is the non-invertible (two-to-one) fold’s self-opacity: a state cannot read which preimage it came from. No probability, no continuum, no dice. The determinism is non-local and survives Bell, which excludes only local hidden variables. Machine-checked; reproduces from one command. A standalone result within the Smithian Fold Theory of Everything (SFTOE). Full corpus, code, and the run-it-yourself VERIFY.md protocol: https://github.com/MettaMazza/Smithian-Fold-Theory