Core concepts
Runtime architecture
How the SDK, harness, maps, skills, and agent surfaces fit together.
One runtime
Agent or application
│
CLI · MCP · createSession()
│
Shared tool registry
│
Permissions · traces
│
Maps · intent verbs · skills
│
@phone-use/sdk
│
Phone Use iOS backend
│
iOS SimulatorDevice layer
@phone-use/sdk owns lifecycle, observation, action resolution, waiting, normalized errors, and backend capabilities. Transport-specific types do not cross its public boundary.
When model calls happen
| Operation | Model calls |
|---|---|
| SDK action | 0 |
| CLI primitive | 0 |
| Known goto route | 0 |
| Saved skill replay | 0 |
| phone-use task | Yes |
| MCP tool use | Determined by the client agent |