//AGENT-NATIVE APPLICATION VOCABULARY
Host
In the agent-native application model, the Host is the AI system an app mounts into: the model, its inference, its tool execution, its permission boundary, and its runtime surface. The Host supplies general intelligence and conversation, plus frontier upgrades as the model improves. The agent-native app supplies what the Host cannot: domain identity, judgment, governance, workflows, and durable state. A Host can be a frontier platform or a local model.
The Host boundary is what makes the category's economics work. Because the Host carries inference, the publisher of an agent-native app doesn't have to host frontier compute or price it into the product. Because the Host enforces its own permission boundary, the app's declared tools operate inside limits the user's platform already controls.
Two Host classes are first-class in the specification: frontier Hosts, for reach and inherited upgrades, and local-model Hosts, for sovereignty, air-gap support, and controlled egress. The same package targets both through adapters, which is what 'designed to be portable' means in practice.