Two stances toward the model

Finally, two stances worth naming because they shape design:

• The model as a smart but unreliable collaborator. It will occasionally produce malformed output, hallucinate, or call a tool wrong. Design defensively: validate its outputs, give every tool call a defined result, and degrade gracefully. (This stance drives Chapter 13.)
• The model as a component you can swap. Today's best model won't be next quarter's. Decouple from any specific provider so you can change models without rewriting your agent. (This stance drives Chapter 4.)

Hold both stances and you'll make architecture decisions that age well.