The only things flowing in the circuit are electrons. Current doesn't flow. Current is flow.
The electrons flow in the circuit external to the battery from the negative terminal to the positive terminal.
Electrons will flow in a branch according the the electric field along the branch. According to the diagram the electric field is more positive at A relative to B, so the electrons will flow from B to A.
Internal to the battery: Negative ions flow toward the positive terminal. Positive ions flow toward the negative terminal. For me this is an interesting visualization.
Andre-Marie Ampere traced current around a circuit with a compass. He found that the compass deflected in the same direction whether tracing the circuit external the the voltaic pile or the circuit internal to it. Electrons and protons had not been discovered yet, but the scientists of the day new about positive and negative charge.
Eventually the direction for conventional current was set as the direction of charge flow that produce the same magnetic deflection as does the flow of positive charge. This means that positive charge flowing in one direction produce the same magnetic field as negative charge flowing opposite.
So therefore the current in the branch with the red arrows will be in the direction from A to B because the electric field along the branch will move the electrons from B to A.