Did the Model Upgrade Break Your AI Agent?

Model upgrades can unexpectedly alter AI agent behavior without internal code changes, creating issues that are difficult to track in git history or roll back. As companies transition from experiments to production, the focus is shifting from finding the smartest model to efficient operation. This has highlighted the need for a model routing infrastructure layer to manage requests based on cost and reliability, a trend exemplified by Stripe acquiring OpenRouter to enhance multi-model AI application control.