Choose an agent and model
SHORT ANSWER
Choose the agent when the session starts. A session stays bound to that backend; models can be changed within the choices that backend and your gateway expose.
Choose the backend at session start
- Claude Code supports Claude permission modes and model aliases.
- Codex uses a Cautious, Balanced, Autonomous, or Full auto preset mapped to approval policy and sandbox settings.
- OpenCode runs full access because its run command has no interactive approval protocol.
Choose a model
Use the model picker in a session. If Claude Code is routed through an Anthropic-compatible gateway, custom ids and saved gateway presets are passed to that local CLI; the gateway decides which model the id reaches.