RadioGroup

{
  "type": "object",
  "properties": {
    "component": {
      "const": "RadioGroup"
    },
    "label": {
      "$ref": "https://a2ui.org/specification/v1_0/common_types.json#/$defs/DynamicString",
      "description": "Group label. Required — the accessible name of the whole group."
    },
    "value": {
      "$ref": "https://a2ui.org/specification/v1_0/common_types.json#/$defs/DataBinding",
      "description": "Data binding for the chosen option's value, always {\"path\": ...}."
    },
    "options": {
      "type": "array",
      "items": {
        "oneOf": [
          {
            "type": "string"
          },
          {
            "type": "object",
            "properties": {
              "value": {
                "type": "string"
              },
              "label": {
                "type": "string"
              }
            },
            "required": [
              "value",
              "label"
            ],
            "additionalProperties": false
          }
        ]
      },
      "description": "All options are visible — use RadioGroup for 2–6 choices, SelectField beyond that."
    },
    "hint": {
      "$ref": "https://a2ui.org/specification/v1_0/common_types.json#/$defs/DynamicString"
    },
    "checks": {
      "type": "array",
      "items": {
        "type": "object",
        "description": "A validation check. Spec-shaped — `condition` is a FunctionCall — but narrowed to the renderer's built-ins, and `message` is required because a check with no human text fails silently.",
        "properties": {
          "condition": {
            "type": "object",
            "properties": {
              "call": {
                "enum": [
                  "required",
                  "email",
                  "regex",
                  "length",
                  "numeric"
                ],
                "description": "One of the protocol's built-in validation functions. The renderer supplies the field's current value automatically."
              },
              "args": {
                "type": "object",
                "description": "Arguments beyond the value: regex takes {\"pattern\"}, length and numeric take {\"min\"} and/or {\"max\"}. required and email take none."
              }
            },
            "required": [
              "call"
            ],
            "additionalProperties": false
          },
          "message": {
            "type": "string",
            "description": "Human text shown when the check fails. Always required."
          }
        },
        "required": [
          "condition",
          "message"
        ],
        "additionalProperties": false
      },
      "description": "Validation rules, evaluated by the renderer as the user types. Submission is blocked while any check fails."
    }
  },
  "required": [
    "label",
    "value",
    "options"
  ]
}

### RadioGroup — one of a few, all visible

Same shape as SelectField minus `placeholder`. Use for 2–6 options; SelectField beyond that.

```
{"id":"severity","component":"RadioGroup","label":"Severity","value":{"path":"/report/severity"},"options":[{"value":"sev1","label":"Sev 1 — total outage"},{"value":"sev2","label":"Sev 2 — degraded"},{"value":"sev3","label":"Sev 3 — cosmetic"}],"checks":[{"condition":{"call":"required"},"message":"Choose a severity."}]}
```