{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://a2ui.org/specification/v1_0/client_capabilities.json",
    "title": "A2UI Client Capabilities Schema",
    "description": "A schema for the a2uiClientCapabilities object, which is sent from the client to the server as part of the A2A metadata to describe the client's UI rendering capabilities.",
    "type": "object",
    "properties": {
        "v1.0": {
            "type": "object",
            "description": "The capabilities structure for version 1.0 of the A2UI protocol.",
            "properties": {
                "supportedCatalogIds": {
                    "type": "array",
                    "description": "The URI of each of the component and function catalogs that is supported by the client.",
                    "items": { "type": "string" }
                },
                "inlineCatalogs": {
                    "type": "array",
                    "description": "An array of inline catalog definitions, which can contain both components and functions. This should only be provided if the agent declares 'acceptsInlineCatalogs: true' in its capabilities.",
                    "items": { "$ref": "#/$defs/Catalog" }
                }
            },
            "required": ["supportedCatalogIds"]
        }
    },
    "required": ["v1.0"],
    "$defs": {
        "FunctionCallValidationSchema": {
            "type": "object",
            "description": "JSON Schema structure that validates a wire-level FunctionCall object.",
            "properties": {
                "type": {
                    "const": "object"
                },
                "description": {
                    "type": "string"
                },
                "properties": {
                    "type": "object",
                    "properties": {
                        "call": {
                            "type": "object",
                            "properties": {
                                "const": { "type": "string" }
                            },
                            "required": ["const"]
                        },
                        "args": {
                            "type": "object",
                            "description": "A JSON Schema describing the expected arguments (args) for this function.",
                            "$ref": "https://json-schema.org/draft/2020-12/schema"
                        }
                    },
                    "required": ["call"],
                    "additionalProperties": false
                },
                "required": {
                    "type": "array",
                    "items": { "type": "string" },
                    "contains": { "const": "call" }
                },
                "unevaluatedProperties": {
                    "type": "boolean"
                },
                "additionalProperties": {
                    "type": "boolean"
                }
            },
            "required": ["type", "properties", "required"]
        },
        "FunctionDefinition": {
            "type": "object",
            "description": "Describes a function's validation schema and interface metadata.",
            "allOf": [
                {
                    "$ref": "#/$defs/FunctionCallValidationSchema"
                },
                {
                    "type": "object",
                    "properties": {
                        "returnType": {
                            "type": "string",
                            "enum": ["string", "number", "boolean", "array", "object", "any", "void"],
                            "description": "The type of value this function returns."
                        },
                        "callableFrom": {
                            "type": "string",
                            "enum": ["clientOnly", "remoteOnly", "clientOrRemote"],
                            "default": "clientOnly",
                            "description": "Specifies where this function can be invoked from."
                        }
                    },
                    "required": ["returnType"]
                }
            ],
            "unevaluatedProperties": false
        },
        "Catalog": {
            "type": "object",
            "description": "A collection of component and function definitions.",
            "properties": {
                "$schema": { "type": "string" },
                "$id": { "type": "string" },
                "$defs": {
                    "type": "object",
                    "description": "Standardized schema definitions referenced from outside the catalog file.",
                    "properties": {
                        "surfaceProperties": {
                            "title": "A2UI Surface Properties Schema",
                            "description": "A JSON Schema that defines the catalog's surface properties.",
                            "$ref": "https://json-schema.org/draft/2020-12/schema"
                        },
                        "anyComponent": {
                            "title": "A2UI Any Component Schema",
                            "description": "Unified validation schema for all components.",
                            "$ref": "https://json-schema.org/draft/2020-12/schema"
                        },
                        "anyFunction": {
                            "title": "A2UI Any Function Schema",
                            "description": "Unified validation schema for all functions.",
                            "$ref": "https://json-schema.org/draft/2020-12/schema"
                        }
                    },
                    "required": ["anyComponent", "anyFunction"],
                    "additionalProperties": false
                },
                "title": {
                    "type": "string",
                    "description": "The title of the catalog."
                },
                "description": {
                    "type": "string",
                    "description": "A human-readable description of the catalog."
                },
                "catalogId": {
                    "type": "string",
                    "description": "Unique identifier for this catalog."
                },
                "instructions": {
                    "type": "string",
                    "description": "Markdown-formatted design guidelines or instructions specific to this catalog."
                },
                "components": {
                    "type": "object",
                    "description": "Definitions for UI components supported by this catalog.",
                    "additionalProperties": {
                        "$ref": "https://json-schema.org/draft/2020-12/schema"
                    }
                },
                "functions": {
                    "type": "object",
                    "description": "Definitions for functions supported by this catalog.",
                    "additionalProperties": {
                        "$ref": "#/$defs/FunctionDefinition"
                    }
                }
            },
            "required": ["catalogId"],
            "additionalProperties": false
        }
    }
}