Canonical Chirality and the Global Asymmetry Condition for Temporal Persistence

The canonical deparameterization of time produces the familiar branch label σ = ±1, but its geometric meaning has always been underspecified. This paper shows that σ is the sign of a genuine three-dimensional enantiomeric structure on canonical phase space. The σ = +1 and σ = −1 branches are related by a simultaneous chiral flip, vertical inversion, and horizontal reflection — exactly the transformation that turns one optical isomer into its nonsuperimposable mirror image. Under chirally complete admissibility, the branch-oriented temporal ledger cancels exactly, just as a racemic mixture produces no net optical rotation. This is the Global Asymmetry Condition for Temporal Persistence (GACTP): determinate temporal evolution requires a global selector that excludes one chirality class from admissibility. The Band-anchored Designed-with-Time (DWT) Model serves as a clean control case where both the deparameterized clock and the enantiomeric branch pair are fully explicit. The paper establishes the need for such a selector but does not construct one; identifying the physical principle that breaks the symmetry is left for future work.