NumberField

{
  "type": "object",
  "properties": {
    "component": {
      "const": "NumberField"
    },
    "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 (a raw number), always {\"path\": ...}."
    },
    "min": {
      "type": "number"
    },
    "max": {
      "type": "number"
    },
    "step": {
      "type": "number",
      "description": "Increment granularity, e.g. 0.5. Default 1."
    },
    "unit": {
      "type": "string",
      "description": "Unit rendered beside the input: 'ms', '%', 'GB', or an ISO 4217 currency code."
    },
    "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"
  ]
}

### NumberField — a number with bounds and a unit

| prop     | type       | required | notes                                             |
| -------- | ---------- | -------- | ------------------------------------------------- |
| `label`  | string     | yes      | visible label and accessible name                 |
| `value`  | `{"path"}` | yes      | always a binding; the answer is a raw number      |
| `min`    | number     | no       |                                                   |
| `max`    | number     | no       |                                                   |
| `step`   | number     | no       | increment granularity; default `1`                |
| `unit`   | string     | no       | `"GB"`, `"%"`, or a currency code like `"USD"`    |
| `hint`   | string     | no       |                                                   |
| `checks` | check[]    | no       | `numeric` with `{"min"}`/`{"max"}` mirrors bounds |

```
{"id":"replicas","component":"NumberField","label":"Replica count","value":{"path":"/svc/replicas"},"min":1,"max":20,"hint":"Production runs at least 2.","checks":[{"condition":{"call":"numeric","args":{"min":1,"max":20}},"message":"Choose between 1 and 20 replicas."}]}
```