  WASP-107 b seems to be a poster child of the long-suspected high-eccentricity
migration scenario. It is on a 5.7-day, polar orbit. The planet is Jupiter-like
in radius but Neptune-like in mass with exceptionally low density. WASP-107 c
is on a 1100-day, $e=0.28$ orbit with at least Saturn mass. Planet b may still
have a residual eccentricity of $0.06\pm 0.04$: the ongoing tidal dissipation
leads to the observed internally heated atmosphere and hydrodynamic atmospheric
erosion. We present a population synthesis study coupling octopole Lidov-Kozai
oscillations with various short-range forces, while simultaneously accounting
for the radius inflation and tidal disruption of the planet. We find that a
high-eccentricity migration scenario can successfully explain nearly all
observed system properties. Our simulations further suggest that the initial
location of WASP-107 b at the onset of migration is likely within the snowline
($<0.5\,{\rm AU}$). More distant initial orbits usually lead to tidal
disruption or orbit crossing. WASP-107 b most likely lost no more than 20% of
its mass during the high-eccentricity migration, i.e. it did not form as a
Jupiter-mass object. More vigorous tidally-induced mass loss leads to
disruption of the planet during migration. We predict that the current-day
mutual inclination between the planets b and c is substantial: at least
25-55$^\circ$ which may be tested with future Gaia astrometric observations.
Knowing the current-day mutual inclination may further constrain the initial
orbit of planet b. We suggest that the proposed high-eccentricity migration
scenario of WASP-107 may be applicable to HAT-P-11, GJ-3470, HAT-P-18, and
GJ-436 which have similar orbital architectures.
