TextArea

{
  "type": "object",
  "properties": {
    "component": {
      "const": "TextArea"
    },
    "label": {
      "$ref": "https://a2ui.org/specification/v1_0/common_types.json#/$defs/DynamicString",
      "description": "Visible field label. Required — the accessible name."
    },
    "value": {
      "$ref": "https://a2ui.org/specification/v1_0/common_types.json#/$defs/DataBinding",
      "description": "Data binding for the answer, always {\"path\": ...}."
    },
    "rows": {
      "type": "number",
      "description": "Visible line count. Default 3."
    },
    "maxLength": {
      "type": "number",
      "description": "Maximum characters; the field shows a live counter when set."
    },
    "placeholder": {
      "type": "string"
    },
    "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"
  ]
}

### TextArea — multi-line text

| prop          | type       | required | notes                                   |
| ------------- | ---------- | -------- | --------------------------------------- |
| `label`       | string     | yes      | visible label and accessible name       |
| `value`       | `{"path"}` | yes      | always a binding                        |
| `rows`        | number     | no       | visible lines; default `3`              |
| `maxLength`   | number     | no       | shows a live character counter when set |
| `placeholder` | string     | no       |                                         |
| `hint`        | string     | no       |                                         |
| `checks`      | check[]    | no       | `length` with `{"min"}` pairs well here |

```
{"id":"details","component":"TextArea","label":"What happened?","value":{"path":"/report/details"},"rows":5,"maxLength":2000,"checks":[{"condition":{"call":"length","args":{"min":30}},"message":"A sentence or two more helps us reproduce it."}]}
```