Three choices serve different purposes: the provider supplies access, the model handles a request, and the Agent defines working instructions and permissions.
Make a model available
Open Settings → Providers, add a provider and complete the authentication offered for it. This may be an API key or an authorization flow. Connected-provider details allow reconnecting or removing access. Model visibility controls affect which models appear in selection lists.
Back in the composer, select the model for that conversation. Adding an account and choosing a session model are separate steps.
For models exposed by Magpie, first configure its OpenCode connection on the execution host. The Magpie guide separates model access, plugin sign-ins and usage display.
Shape how an Agent works
Under Settings → Agents, create or select an Agent. The editor offers scope, description, primary/subagent mode, model and variant, and a system prompt.
Permissions use allow, ask or deny, including pattern-based rules. Open the advanced editor when you need to adjust those rules; inspect saved permissions separately. A broad wildcard can affect more operations than a narrowly targeted pattern.
The current Agent editor has no temperature control. Use the fields actually shown rather than looking for an older parameter form.