# Models

Model selection is handled through the model registry.

## Registry Responsibilities

- built-in model definitions
- alias resolution
- family grouping
- provider-specific model identifiers
- capability metadata

## Families

- Opus
- Sonnet
- Haiku

## Related Systems

- `tokens.md` for context-window handling
- `budget.md` for pricing and cost control
- `cloud-providers.md` for provider-specific routing
