What is the proper colour to paint the door jamb? The colour of the inside door or the outside door colour?
In our experience, we will paint to the stop of the door.
What I mean by this is, where the door is designed to close there is a door stop built as part of the door jamb. The edge of the door stop is our demarcation line.
The answer to your question lay in if the door swings to the outside or inside. If an out swing door, paint to the edge of the door stop the exterior color. If an in swing door, paint to the inside edge of the door stop.