  Soft gamma-ray emission (100 keV -- 10 MeV) has previously been detected in
the hard state of several microquasars. In some sources, this emission was
found to be highly polarized and was suggested to be emitted at the base of the
jet. Until now, no $\gamma$-ray polarization had been found in any other state.
Using INTEGRAL/IBIS, we studied the soft gamma-ray spectral and polarization
properties of Swift J1727.8-1613 throughout its outburst. We detect a highly
polarized spectral component in both the hard intermediate state and the early
stages of the soft intermediate state above 210 keV. In the hard intermediate
state, the polarization angle significantly deviates from the compact jet angle
projected onto the sky, whereas in the soft intermediate they are closely
aligned. This constitutes the first detection of jet-aligned polarization in
the soft gamma-ray for a microquasar. We attribute this polarized spectral
component to synchrotron emission from the jet, which indicates that some of
the jet might persist into the softer states.
