  It is an important question whether the final/initial state gluonic
interactions which lead to naive-time-reversal-odd single-spin asymmetries and
diffraction at leading twist can be associated in a definite way with the
light-front wave function hadronic eigensolutions of QCD. We use light-front
time-ordered perturbation theory to obtain augmented light-front wave functions
which contain an imaginary phase which depends on the choice of advanced or
retarded boundary condition for the gauge potential in light-cone gauge. We
apply this formalism to the wave functions of the valence Fock states of
nucleons and pions, and show how this illuminates the factorization properties
of naive-time-reversal-odd transverse momentum dependent observables which
arise from rescattering. In particular, one calculates the identical
leading-twist Sivers function from the overlap of augmented light-front
wavefunctions that one obtains from explicit calculations of the single-spin
asymmetry in semi-inclusive deep inelastic lepton-polarized nucleon scattering
where the required phases come from the final-state rescattering of the struck
quark with the nucleon spectators.
