# Shadcn Cross-Question Rule

> A rule that sends you back

- Type: example, free and open source (MIT)
- Component: [Questionnaire](https://web.dev.reui.io/components/questionnaire.md)
- Page: https://web.dev.reui.io/components/questionnaire/c-questionnaire-6
- Docs (Base UI): https://ui.shadcn.com/docs/components/base/questionnaire.md
- Docs (Radix UI): https://ui.shadcn.com/docs/components/radix/questionnaire.md
- MCP: `get_example("c-questionnaire-6")`
- Registry item: https://web.dev.reui.io/r/styles/base-nova/c-questionnaire-6.json
- Uses: Button, Card, Questionnaire

## Best for

Controlled step position that a failed submit check moves back, with custom error copy holding Next until the plan or region changes

## Agent notes

- Replace the `self-managed` and `starter` check in `handleSubmit` and its `PLAN_CONFLICT` copy with your own cross question rule
- Each region and plan choice clears `planError` in its `onChange`, since a set `invalid` flag keeps blocking Next

## When not to use

- Checks that each question can settle alone, with no rule across two answers: use [Guided Setup](https://web.dev.reui.io/components/questionnaire/c-questionnaire-1.md) (`get_example("c-questionnaire-1")`)

## Install

```bash
npx shadcn@latest add @reui/c-questionnaire-6
```

## About Shadcn Questionnaire

### When to use

- Onboarding and setup flows that ask one single or multiple answer question per screen
- Short intake surveys, such as how a visitor heard about you or what they are moving off
- Question flows with an optional step, a branch that joins on an earlier answer or a rule across answers

### When not to use

- Steps that each hold a whole screen of mixed fields rather than one question: use [Stepper](https://web.dev.reui.io/components/stepper.md) (`get_component("stepper")`)
- A bar that reports how far an upload, a goal or a task has got, with no questions: use [Progress](https://web.dev.reui.io/components/progress.md) (`get_component("progress")`)
- A complete first-run screen that also collects a profile, a timezone and teammate invites: use the [Onboarding blocks](https://web.dev.reui.io/blocks/application/onboarding.md)

### Agent notes

- A `QuestionnaireItem` whose `name` is missing from the root `items` list is left out of the flow and the count, with only a dev warning
- `handleSubmit` reads the answers with `FormData` and only renders a local confirmation; send them to your API from there
- `QuestionnaireActions` is a 3 column grid placed for Previous, Skip and Next or Submit, so keep any other button outside it

Every ReUI item has a twin like this one; the index is https://web.dev.reui.io/llms.txt. Agents with the ReUI MCP (https://web.dev.reui.io/docs/mcp) get the same guidance from the getters named above.