Conditional logic

Show a field or a whole page only when earlier answers match. Conditions live in the schema and are evaluated by the components and by the server, so a hidden field is never required and never stored.

{ key: 'role', type: 'dropdown', label: 'Role', options: ['Founder', 'Researcher', 'Other'], required: true },
{ key: 'role_other', type: 'short_text', label: 'Which role?', required: true,
  showWhen: { field: 'role', op: 'eq', value: 'Other' } },

Page-level:

{ title: 'Your team', showWhen: { field: 'role', op: 'in', value: ['Founder', 'Researcher'] }, fields: [ … ] }

Groups:

showWhen: { all: [ { field: 'team_size', op: 'gte', value: 10 }, { any: [ { field: 'interest', op: 'contains', value: 'surveys' }, { field: 'timeline', op: 'neq', value: 'Just looking' } ] } ] }

Operators: eq, neq, in, notIn, contains, notContains (strings and multiple choice), gt, gte, lt, lte (numbers, dates), empty, notEmpty.

Rules:

• A condition may reference fields on the same page or earlier pages, never later ones. defineForm checks this.
• A page with no visible fields is skipped; the progress indicator counts visible pages only.
• Hidden values are dropped before a partial save or a submit, and the server drops them again.
• Conditions are part of the schema version, so changing one creates a new version.

Explicit jumps and calculated fields are not supported. If showWhen turns out not to be enough, tell us.