CheckboxGroup

{
  "type": "object",
  "properties": {
    "component": {
      "const": "CheckboxGroup"
    },
    "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 values as an array of strings, always {\"path\": ...}. Seed [] (or a preselection) with updateDataModel."
    },
    "options": {
      "type": "array",
      "items": {
        "oneOf": [
          {
            "type": "string"
          },
          {
            "type": "object",
            "properties": {
              "value": {
                "type": "string"
              },
              "label": {
                "type": "string"
              }
            },
            "required": [
              "value",
              "label"
            ],
            "additionalProperties": false
          }
        ]
      }
    },
    "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"
  ]
}

### CheckboxGroup — many of a few

The bound value is an **array of strings**. Seed it (usually `[]`) with `updateDataModel`.

| prop      | type       | required | notes                              |
| --------- | ---------- | -------- | ---------------------------------- |
| `label`   | string     | yes      | group label and accessible name    |
| `value`   | `{"path"}` | yes      | binds a string array               |
| `options` | option[]   | yes      |                                    |
| `hint`    | string     | no       |                                    |
| `checks`  | check[]    | no       | `required` = at least one selected |

```
{"id":"channels","component":"CheckboxGroup","label":"Notify via","value":{"path":"/prefs/channels"},"options":["Email","Slack","PagerDuty"],"hint":"Pick any."}
```