World Model

Biter receives see commands from the sserver and parses them.
Biter maintains a WorldModel which has the absolute location of every object on the field that the agent can or has seen recently.
Static objects are read in at startup.
First, the closest line and flag are used to determine the player's absolute location, then the location of all other objects is deduced from it. Their certainty is set to one.
If the ball is not seen then its updated using dead-reckoning from its previous velocity. The certainty about its location is reduced. When the certainty reaches zero it is removed.
Player positions can be updated the same way.
You will need to decide how fast to forget (reduce phantom objects).