We give a global, intrinsic, and co-ordinate-free quantization formalism for Gromov{
Witten invariants and their B-model counterparts, which simultaneously generalizes the quantization
formalisms described by Witten, Givental, and Aganagic{Bouchard{Klemm. Descendant potentials
live in a Fock sheaf, consisting of local functions on Givental's Lagrangian cone that satisfy the
(3
g
2)-jet condition of Eguchi{Xiong; they also satisfy a certain anomaly equation, which gen-
eralizes the Holomorphic Anomaly Equation of Bershadsky{Cecotti{Ooguri{Vafa. We interpret
Givental's formula for the higher-genus potentials associated to a semisimple Frobenius manifold in
this setting, showing that, in the semisimple case, there is a canonical global section of the Fock
sheaf. This canonical section automatically has certain modularity properties. When
X
is a variety
with semisimple quantum cohomology, a theorem of Teleman implies that the canonical section
coincides with the geometric descendant potential de ned by Gromov{Witten invariants of
X
. We
use our formalism to prove a higher-genus version of Ruan's Crepant Transformation Conjecture for
compact toric orbifolds. When combined with our earlier joint work with Jiang, this shows that the
total descendant potential for compact toric orbifold
X
is a modular function for a certain group of
autoequivalences of the derived category of
X
.