{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://a2ui.org/specification/v0_10/client_to_server.json",
  "title": "A2UI (Agent to UI) Client-to-Server Event Schema",
  "description": "Describes a JSON payload for a client-to-server event message.",
  "type": "object",
  "minProperties": 2,
  "maxProperties": 2,
  "properties": {
    "version": {
      "const": "v0.10"
    },
    "action": {
      "type": "object",
      "description": "Reports a user-initiated action from a component.",
      "properties": {
        "name": {
          "type": "string",
          "description": "The name of the action, taken from the component's action.event.name property."
        },
        "surfaceId": {
          "type": "string",
          "description": "The id of the surface where the event originated."
        },
        "sourceComponentId": {
          "type": "string",
          "description": "The id of the component that triggered the event."
        },
        "timestamp": {
          "type": "string",
          "format": "date-time",
          "description": "An ISO 8601 timestamp of when the event occurred."
        },
        "context": {
          "type": "object",
          "description": "A JSON object containing the key-value pairs from the component's action.event.context, after resolving all data bindings.",
          "additionalProperties": true
        }
      },
      "required": [
        "name",
        "surfaceId",
        "sourceComponentId",
        "timestamp",
        "context"
      ]
    },
    "functionResponse": {
      "properties": {
        "functionCallId": {
          "$ref": "common_types.json#/$defs/CallId",
          "description": "Unique ID for the instance of this function. MUST be copied verbatim from the function invocation."
        },
        "value": {
          "description": "The return value of the function invocation.",
          "type": [
            "string",
            "number",
            "boolean",
            "array",
            "object",
            "null"
          ]
        }
      },
      "required": ["functionCallId", "value"],
      "unevaluatedProperties": false
    },
    "error": {
      "description": "Reports a client-side error.",
      "oneOf": [
        {
          "type": "object",
          "title": "Validation Failed Error",
          "properties": {
            "code": {
              "const": "VALIDATION_FAILED"
            },
            "surfaceId": {
              "type": "string",
              "description": "The id of the surface where the error occurred."
            },
            "path": {
              "type": "string",
              "description": "The JSON pointer to the field that failed validation (e.g. '/components/0/text')."
            },
            "message": {
              "type": "string",
              "description": "A short one or two sentence description of why validation failed."
            }
          },
          "required": ["code", "path", "message", "surfaceId"],
          "additionalProperties": false
        },
        {
          "type": "object",
          "title": "Generic Error",
          "properties": {
            "code": {
              "not": {
                "const": "VALIDATION_FAILED"
              }
            },
            "message": {
              "type": "string",
              "description": "A short one or two sentence description of why the error occurred."
            },
            "surfaceId": {
              "type": "string",
              "description": "The id of the surface where the error occurred."
            },
            "functionCallId": {
              "$ref": "common_types.json#/$defs/CallId",
              "description": "The unique ID of the function invocation, which must be identical to the value specified in the function invocation."
            }
          },
          "required": ["code", "message"],
          "oneOf": [
            {
              "required": ["surfaceId"],
              "not": {
                "required": ["functionCallId"]
              }
            },
            {
              "required": ["functionCallId"],
              "not": {
                "required": ["surfaceId"]
              }
            }
          ],
          "additionalProperties": true
        }
      ]
    }
  },
  "oneOf": [
    {
      "required": ["action", "version"]
    },
    {
      "required": ["functionResponse", "version"]
    },
    {
      "required": ["error", "version"]
    }
  ]
}
