Start here. This is the direct spoken answer to practice first.
Overview
A larger context window does not make indiscriminate context assembly correct. The goal is sufficient evidence with clear provenance and bounded cost.
I start from the task and include only the instructions, current user input, conversation state, and supporting facts needed to complete it. I prefer authoritative and recent data, keep the context within a deliberate token budget, and define what the model should do when evidence is missing. Context is a request-scoped view, not the system of record.