The runtime is the operational home of the agent. It handles the actual execution loop: receive input, assemble context, call the model, use tools, store state, return output, log actions, and trigger the next step.
For Growth Marshal's audience, the runtime is usually invisible, but it matters. If agents are going to become business infrastructure, they need somewhere reliable to run. That means scheduling, retries, permissions, monitoring, logging, and failure handling, not just a clever prompt in a browser tab.