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Schemas define reusable object shapes. 
schema task {
    title: string
    priority: enum { low, medium, high }
    tags: [string]
}
Use schemas anywhere a type is expected. 
input {
    task: schema.task
}

agent summarize {
    model: model.fast
    instruction: "Summarize {{ input.task.title }}."

    output {
        summary: string
        priority: schema.task.priority
    }
}

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Nested reusable fields

A schema field can be referenced from another schema. 
schema shared {
    status: enum {
        draft
        ready
        published
    }
}

schema article {
    title: string
    status: schema.shared.status
}

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Supported schema field types

Schemas support the full type system. Common options:
  • Primitive: string, number, float, boolean, null
  • Any object: object
  • Arrays: [string], fixed length [string; 3]
  • Tuples: (string, number)
  • Objects: { title: string, score: number }
  • Enums: enum { draft, ready, published }
  • Unions: string | number
  • Nullable values: maybe string
  • Schema references: schema.shared.status
  • Variants (tagged unions): variant kind { ... }
Example with multiple types: 
schema typed_example {
    name: string
    age: number
    ratio: float
    active: boolean
    metadata: object
    nickname: maybe string
    tags: [string]
    fixed_tags: [string; 3]
    coordinates: (number, number)
    status: enum { draft, ready, published }
    fallback: string | number
}

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Variants

Use variant when a value can be one of multiple structured cases, each identified by a discriminator field. 
schema event_payload {
    payload: variant type {
        user_created {
            user_id: string
        }

        "user.deleted" {
            user_id: string
            reason: maybe string
        }
    }
}
In this example, type is the discriminator and each case defines its own object shape.

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Field descriptions

Use triple-slash comments to document schema fields. These descriptions are preserved for schema-aware tooling and can improve structured output quality. 
schema release_note {
    /// Short title shown to the user
    title: string

    /// Severity bucket
    impact: enum { low, medium, high }
}

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Enum formatting

Inline enum variants use commas: 
enum { draft, ready, published }
Multiline enum variants do not require commas: 
enum {
    draft
    ready
    published
}