FORM-005: field outside a form

Error: the page doesn't build until this is fixed.

A field belongs to the form it's in: the form sends its value, and the form's tool for AI agents lists it. Fields are known when the page compiles, so they can't be inside for or if in the form either.

Fails

page(title: "Shoes", description: "All our running shoes, from light racers to trail shoes.") {
  h1 "Shoes"
  field("email", type: Email, label: "Email")
}

error[FORM-005]: `field` must be inside a form
 --> page.hypra:3:3
  |
3 |   field("email", type: Email, label: "Email")
  |   ^^^^^
  = docs: https://hypralang.dev/rules/form-005/

1 error, 0 warnings

Fixed

page(title: "Shoes", description: "All our running shoes, from light racers to trail shoes.") {
  h1 "Shoes"
  form("/newsletter", name: "newsletter") {
    field("email", type: Email, label: "Email")
    button "Subscribe"
  }
}

A choice that comes from data is a Choice field, whose options are data; a field that only some people fill in is optional: true.