Start here. This is the direct spoken answer to practice first.
Overview
Provider limits are downstream capacity constraints, not errors to solve with unlimited local queues.
I control admission before starting expensive work, limit concurrent calls, and maintain bounded queues for tasks that can wait. Capacity accounts for both requests and token volume because a few large prompts can consume a quota faster than many small ones. When capacity is exhausted, the system returns a clear retryable response, defers eligible background work, or degrades instead of accepting an unbounded backlog.