  We present the first simultaneous global QCD analysis of spin-dependent
parton distribution functions alongside their spin-averaged counterparts and
pion, kaon, and unidentified hadron fragmentation functions. This analysis
includes all data relevant for constraining the polarized light quark sea
asymmetry $\Delta \bar{u} - \Delta \bar{d}$, in particular the latest polarized
$W$-lepton production data from the STAR collaboration at RHIC and
semi-inclusive deep inelastic scattering data from COMPASS, allowing the most
robust extraction available with minimal theoretical assumptions. We also
extract a self-consistent set of antiquark polarization ratios $\Delta
\bar{u}/\bar{u}$ and $\Delta \bar{d}/\bar{d}$ and determine the signs of the
truncated contributions to the proton spin from the light antiquarks.
