Czechoslovakia was different. It had a stable democratic government that didn't have a Communist-allied majority and there was no prospect of forming a permanent ruling coalition of just Communists. Then the Communist party took over in a coup while Soviet troops waited just outside.
Czechoslovakia was different, but not because it had a stable democratic government. Rather the communists were (initially) actually voted into power with considerable popular support.
It was 1946 and the Communist Party got almost a third of the vote. Gottwald became prime minister with Benes as President. The Czechoslovak communists operated more or less independently of Moscow to the point they entertained joining the Marshall Plan, at which point Stalin presumably went enough is enough, and tightened the reins, hence the "coup", after which point the country followed the standard Eastern Bloc path to Stalinism as you described.
tl;dr a democracy that voted Stalinists into government can't really be considered "stable"