{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "validator-descriptor.schema.json",
  "title": "ValidatorDescriptor",
  "description": "A single backend/UI validator applied to an entity property or form field.",
  "markdownDescription": "AI guidance: always set `type`. Use `required` for mandatory input, `minLength`/`maxLength`/`stringLength` for strings, `min`/`max`/`range` for numbers and comparable values, `pattern` or `regularExpression` for regex, and `email`, `phone`, `url`, or `creditCard` for common formats. Use lower-case validator names for new JSON. Add `message` only when a custom localized/user-facing message is needed.",
  "type": "object",
  "required": ["type"],
  "properties": {
    "type": {
      "type": "string",
      "description": "Validator type. Prefer lower-case values in descriptor JSON; PascalCase aliases are accepted for compatibility.",
      "enum": [
        "required",
        "Required",
        "minLength",
        "MinLength",
        "maxLength",
        "MaxLength",
        "stringLength",
        "StringLength",
        "min",
        "Min",
        "minimum",
        "Minimum",
        "max",
        "Max",
        "maximum",
        "Maximum",
        "range",
        "Range",
        "pattern",
        "Pattern",
        "regularExpression",
        "RegularExpression",
        "email",
        "Email",
        "emailAddress",
        "EmailAddress",
        "phone",
        "Phone",
        "url",
        "Url",
        "creditCard",
        "CreditCard"
      ]
    },
    "message": {
      "type": "string",
      "description": "Optional custom error message shown when validation fails. Omit to use the default localized message."
    },
    "length": {
      "type": "integer",
      "description": "Length value for minLength or maxLength validators. Example: { \"type\": \"maxLength\", \"length\": 128 }.",
      "minimum": 0
    },
    "minimumLength": {
      "type": "integer",
      "description": "Minimum length for stringLength validator.",
      "minimum": 0
    },
    "maximumLength": {
      "type": "integer",
      "description": "Maximum length for stringLength validator.",
      "minimum": 0
    },
    "value": {
      "type": "number",
      "description": "Generic numeric value alias for single-value validators such as min/minimum, max/maximum, minLength/maxLength, and stringLength maximumLength."
    },
    "minimum": {
      "type": "number",
      "description": "Minimum value for min/minimum or range validators."
    },
    "maximum": {
      "type": "number",
      "description": "Maximum value for max/maximum or range validators."
    },
    "pattern": {
      "type": "string",
      "description": "Regular expression pattern for pattern/regularExpression validators. Store the regex pattern string only; do not include leading/trailing slashes."
    },
    "allowEmptyStrings": {
      "type": "boolean",
      "description": "Whether required validation should allow empty strings. Usually false for user-entered text."
    }
  },
  "additionalProperties": true,
  "examples": [
    { "type": "required" },
    { "type": "maxLength", "length": 128 },
    { "type": "range", "minimum": 0, "maximum": 100 },
    { "type": "pattern", "pattern": "^[A-Z]{3}-[0-9]{4}$", "message": "Code must match ABC-1234." },
    { "type": "email" }
  ]
}