Smug
Etymology
From a Low German or Dutch word (smuk) meaning "neat, trim, sleek." Early English "smug" meant well-groomed and spruce — pleasingly tidy. The sense curdled: from looking neatly pleased with one’s appearance, it came to mean being obnoxiously pleased with oneself in general.
adjective · /SMUG/
Excessively pleased with oneself in a self-satisfied, self-righteous way.
What it names
The insufferable contentment of someone who is quietly certain they are right and want you to notice.
Example
She wore a smug little smile all through the meeting, having predicted this outcome weeks earlier.
Related idea
Complacent is a lazy, dangerous contentment that stops trying; smug is contentment worn on the face, a self-satisfaction that irritates others.