TextField

{
  "type": "object",
  "properties": {
    "component": {
      "const": "TextField"
    },
    "label": {
      "$ref": "https://a2ui.org/specification/v1_0/common_types.json#/$defs/DynamicString",
      "description": "Visible field label, e.g. 'Work email'. Required — it is the field's accessible name."
    },
    "value": {
      "$ref": "https://a2ui.org/specification/v1_0/common_types.json#/$defs/DataBinding",
      "description": "Data binding for the answer, always {\"path\": ...}. Seed a default by writing that path with updateDataModel; the user's input is written back to it."
    },
    "kind": {
      "enum": [
        "text",
        "email",
        "url",
        "tel",
        "secret"
      ],
      "description": "Input treatment and mobile keyboard. 'secret' masks input. Default 'text'."
    },
    "placeholder": {
      "type": "string",
      "description": "Example content shown while empty. Never a substitute for label."
    },
    "hint": {
      "$ref": "https://a2ui.org/specification/v1_0/common_types.json#/$defs/DynamicString",
      "description": "One line of help under the field, e.g. 'We only use this for receipts.'"
    },
    "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"
  ]
}

### TextField — one line of text

| prop          | type                                              | required | notes                                               |
| ------------- | ------------------------------------------------- | -------- | --------------------------------------------------- |
| `label`       | string                                            | yes      | visible label and accessible name                   |
| `value`       | `{"path"}`                                        | yes      | where the answer lives; always a binding            |
| `kind`        | `"text" \| "email" \| "url" \| "tel" \| "secret"` | no       | input treatment + mobile keyboard; default `"text"` |
| `placeholder` | string                                            | no       | example content, never a label substitute           |
| `hint`        | string                                            | no       | one line of help under the field                    |
| `checks`      | check[]                                           | no       | see rule 3                                          |

```
{"id":"email","component":"TextField","label":"Work email","kind":"email","value":{"path":"/contact/email"},"hint":"We only use this for receipts.","checks":[{"condition":{"call":"required"},"message":"Enter your email."},{"condition":{"call":"email"},"message":"That doesn't look like an email address."}]}
```