THE ANATOMY OF A PRODUCTION HARNESS (COMPONENT MAP)

THE CONTEXT BUILDER The context builder is the component that assembles what the model sees at each step. You learned that the model has a limited context window and that it remembers nothing between calls. So before every call, something must decide exactly what text to send. That something is the context builder. It takes the assembled instructions from the instruction manager, the task, the recent history of what has happened, the results of tool calls, and any saved notes or retrieved documents. It then selects, orders, trims, and formats these pieces so that they fit within the window and put the most useful material where the model will notice it. Think of a personal assistant preparing a briefing folder for a busy executive before each meeting. The assistant does not hand over the entire filing cabinet. The assistant picks the pages that matter, puts the key facts on top, and leaves out the clutter. A poor briefing folder produces a poorly informed executive, no matter how smart that executive is. Part Five, Chapters 18 through 22, is devoted to this component, because context construction is one of the most important skills in the field.