Composite Transport, Projective Holonomy and Operational Spin in Finite Reversible Closure - Paper 12

Composite Transport, Projective Holonomy and Operational Spin in Finite Reversible Closure - Paper 12 Abstract Paper 11 established that driver-level U(1) recurrence is integer-wound while composite frames are generically projective, producing a Z2 parity at the emergent matter level. Paper 12 makes that parity operational. We construct an explicit minimal charge-flux composite, define a strictly local finite-depth transport operator and derive internally at lattice level that closed-loop transport yields a measurable minus-one holonomy in the unique nontrivial involutive sector of compact U(1), namely Wp = -1 (equivalently plaquette phase equal to pi modulo 2pi). No new primitive degrees of freedom are introduced and no SU(2) structure is assumed. The Z2 holonomy arises directly from Abelian surface-product identities and discrete linking on the lattice. This operationalises the projective frame parity identified in Paper 11 and prepares the ground for emergent spinor structure and transport-based spin tests in subsequent papers. Introduction The Finite Reversible Closure (FRC) programme develops a strictly local, finite-dimensional, constraint-defined substrate in which physical structure emerges through admissible reversible update. Paper 9 established minimal U(1) recurrence and infrared universality. Paper 10 constructed the first gauge-invariant charge-flux composite. Paper 11 showed that primitive recurrence is integer-quantised while composite structure is generically projective, yielding a Z2 parity fibre. Paper 12 addresses the next structural question;- How does the Z2 parity identified in Paper 11 become operational and measurable within the lattice theory itself? To answer this, we construct;- A minimal composite excitation combining a unit gauge charge with a local involutive plaquette defect Wp = -1; A strictly local Wilson-line transport operator along oriented lattice paths and A discrete linking notion between loops and plaquette defects. We then derive internally that a closed loop linking the defect once produces a minus-one holonomy acting on the composite state. This derivation uses only;- Compact U(1) group structure; Abelian surface-product identities; Discrete linking on the cubic lattice and Finite-depth local update assumptions. No additional covering groups or spinor primitives are inserted.