Harf reads every word with a morphological analyser and checks sentences against a small set of grammar rules that fire only when they are sure. Nothing you see marked right or wrong was decided by an AI model.
Amber on a word means the analyser does not know it. Names and rare words land there. It is marked, not hidden.
A question mark means more than one reading fits and Harf shows the likeliest.
AI labels the tutor's notes on your writing at Level 4. They are written by a model, checked against the analyser where they quote Arabic, and never used to mark you.
Corrections that come from the grammar rules or from the analyser's spelling check are deterministic: the same text always gets the same marks.