Heads-up, blinds 0.5 and 1, chips only: an open-shove from the small blind or a call of one from the big blind. The answers come from a jam-or-fold equilibrium I solved and checked against published Nash charts, priced in chip-EV, so ICM is not applied.

Spots are only chosen where one action beats the other by at least a quarter of a big blind, so there are no coin flips.