Update saved form

Update a saved form's name, audience targeting, copy, visual theme, or content blocks. Every field is optional - send only what should change.

The headline, description, buttonText, and successMessage fields edit the matching content block and fail with 400 when the form has no such block; replace blocks for structural changes. The blocks array fully replaces the form's content blocks and must keep exactly one required email field and one submit button. An empty redirectUrl switches the form back to its confirmation message.

Blocks render in array order and each needs a unique id and a kind. Input blocks use kind: "form-field" with fieldType (text, email, phone, number, textarea, select, radio, checkbox, consent, hidden), name (the custom attribute key), label, placeholder, required, defaultValue, showLabel, width (full or half), mapsTo (email, firstName, lastName, phone, customAttribute; defaults to customAttribute), and options for choice fields ([{ value, label, id }], where label and id default to value). A hidden field with a defaultValue stores that server-owned value and ignores submitted values; a hidden field without one stores the value the page submits. Validation errors name the offending property, for example blocks[3].options[0].value.