{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://durable-streams.dev/state-protocol/v1",
  "title": "Durable Streams State Protocol Schema",
  "description": "JSON Schema for the Durable Streams State Protocol, an extension of the Durable Streams Protocol that defines change events and control messages for state synchronization",
  "type": "object",
  "oneOf": [
    {
      "$ref": "#/definitions/ChangeMessage"
    },
    {
      "$ref": "#/definitions/ControlMessage"
    }
  ],
  "definitions": {
    "ChangeMessage": {
      "type": "object",
      "title": "Change Message",
      "description": "A change event representing a state mutation (insert, update, or delete)",
      "required": ["type", "key", "headers"],
      "properties": {
        "type": {
          "type": "string",
          "description": "Entity type discriminator. Used to route events to the correct collection or handler in multi-type streams",
          "minLength": 1,
          "examples": ["user", "message", "presence", "config"]
        },
        "key": {
          "type": "string",
          "description": "Entity identifier. Must be unique within a given type",
          "minLength": 1,
          "examples": ["user:123", "msg:456", "config:theme"]
        },
        "value": {
          "description": "The new value for the entity. Required for insert and update operations. For delete operations, this field is typically omitted or set to null",
          "oneOf": [
            { "type": "string" },
            { "type": "number" },
            { "type": "boolean" },
            { "type": "null" },
            { "type": "array" },
            { "type": "object" }
          ]
        },
        "old_value": {
          "description": "Optional previous value. May be included in update or delete operations to enable conflict detection or audit logging",
          "oneOf": [
            { "type": "string" },
            { "type": "number" },
            { "type": "boolean" },
            { "type": "null" },
            { "type": "array" },
            { "type": "object" }
          ]
        },
        "headers": {
          "$ref": "#/definitions/ChangeHeaders"
        }
      },
      "additionalProperties": false,
      "allOf": [
        {
          "if": {
            "properties": {
              "headers": {
                "properties": {
                  "operation": { "const": "insert" }
                }
              }
            }
          },
          "then": {
            "required": ["value"]
          }
        },
        {
          "if": {
            "properties": {
              "headers": {
                "properties": {
                  "operation": { "const": "update" }
                }
              }
            }
          },
          "then": {
            "required": ["value"]
          }
        }
      ]
    },
    "ChangeHeaders": {
      "type": "object",
      "title": "Change Headers",
      "description": "Headers for change messages containing operation metadata",
      "required": ["operation"],
      "properties": {
        "operation": {
          "type": "string",
          "enum": ["insert", "update", "delete"],
          "description": "The operation type. 'insert' creates a new entity, 'update' modifies an existing entity, 'delete' removes an entity"
        },
        "txid": {
          "type": "string",
          "description": "Optional transaction identifier. Used to group related changes or enable transactional semantics",
          "minLength": 1
        },
        "timestamp": {
          "type": "string",
          "format": "date-time",
          "description": "Optional RFC 3339 timestamp indicating when the change occurred. If omitted, servers may use the append timestamp"
        }
      },
      "additionalProperties": false
    },
    "ControlMessage": {
      "type": "object",
      "title": "Control Message",
      "description": "A control event for stream management, separate from data changes",
      "required": ["headers"],
      "properties": {
        "headers": {
          "$ref": "#/definitions/ControlHeaders"
        }
      },
      "additionalProperties": false
    },
    "ControlHeaders": {
      "type": "object",
      "title": "Control Headers",
      "description": "Headers for control messages",
      "required": ["control"],
      "properties": {
        "control": {
          "type": "string",
          "enum": ["snapshot-start", "snapshot-end", "reset"],
          "description": "Control event type. 'snapshot-start' and 'snapshot-end' delimit snapshot boundaries, 'reset' signals a state reset"
        },
        "offset": {
          "type": "string",
          "description": "Optional offset associated with the control event. Used to indicate the stream position at which the control event applies",
          "minLength": 1
        }
      },
      "additionalProperties": false
    },
    "Operation": {
      "type": "string",
      "enum": ["insert", "update", "delete"],
      "description": "Operation type for change events"
    },
    "ControlType": {
      "type": "string",
      "enum": ["snapshot-start", "snapshot-end", "reset"],
      "description": "Control event type"
    },
    "Value": {
      "description": "A generic value type supporting primitives, arrays, and objects",
      "oneOf": [
        { "type": "string" },
        { "type": "number" },
        { "type": "boolean" },
        { "type": "null" },
        {
          "type": "array",
          "items": {
            "$ref": "#/definitions/Value"
          }
        },
        {
          "type": "object",
          "additionalProperties": {
            "$ref": "#/definitions/Value"
          }
        }
      ]
    },
    "Row": {
      "type": "object",
      "description": "A row is a record of values",
      "additionalProperties": {
        "$ref": "#/definitions/Value"
      }
    }
  }
}