# Form Builder

## Objective

Let an admin build a form and change its fields without a developer touching the schema.

An admin-facing form designer plus a stored definition that renders, validates, and collects submissions.

## Before You Begin

This feature is being added to an application that already exists and already
works. Do not scaffold a new project, and do not assume a blank slate.

Inspect the codebase first and establish:

- The existing application structure and where code of this kind already lives.
- The framework and version in use.
- The existing design system — colours, spacing, typography, and component conventions.
- Existing UI components you can reuse instead of writing new ones.
- The existing database structure, if this feature needs to persist anything.
- The existing authentication and authorization system, if this feature is user-scoped.
- Dependencies already installed, so you don't add a library that duplicates one.
- The existing test setup and conventions.

Only start writing code once you understand the above. If the application
already implements part of this feature, extend it rather than replacing it.

## Implementation Instructions

1. Store the form as a definition of ordered fields, each with a type, a stable key, a label, and validation rules. Do not generate a database column per field; answers belong in a submission record tied to the definition.
2. Render the built form with the app's existing Form Field Shell, Inline Validation, and Conditional Form Fields so a generated form is indistinguishable from a hand-written one.
3. Enforce every builder rule again on the server. Client validation is a convenience, and a public endpoint will receive submissions that never touched the rendered form.
4. Version the definition whenever a field is removed or retyped, and render and export old submissions against the version they were made under.
5. A file field on a public form lets an anonymous visitor put bytes into the app's storage, so route it through the existing File Upload and inherit the accepted types and the size ceiling already enforced there. A form the admin built must not be able to accept what the rest of the app rejects.

## UI and UX Requirements

Match the application's existing design system exactly. Reuse its components,
spacing, and typography. This feature should look like it was always there.

## Responsive Requirements

Works on mobile, tablet, and desktop. Touch targets are large enough to hit on a
phone, and nothing overflows horizontally at 320px.

## Accessibility Requirements

- Fully keyboard navigable.
- Correct semantic elements and ARIA roles.
- Visible focus states.
- Meets WCAG AA contrast.
- Dynamic changes are announced to screen readers.
- Respects prefers-reduced-motion.

## Edge Cases

- Deleting a field must not blank the answers already given for it. Keep the version each submission was made against so an export from last month still has its columns.
- Rules configured in the builder must be enforced server-side as well as in the browser. A field that is only required in the page is not required at all.
- A field key that is edited or duplicated silently orphans every answer stored under the old key. Generate keys once, keep them immutable, and let the visible label change freely instead.
- A public form endpoint will be found by bots within days. Rate limit by address and by form and screen for spam without a visible puzzle, reusing the app's existing Rate Limiting rather than adding a second one.
- File fields are the easiest route for arbitrary content into your storage. Enforce size and type server-side, scan what the app already scans, and set a retention period for submitted files.
- Submissions routinely contain personal data. Decide who in the workspace may read them back, and make deleting a submission actually delete its uploaded files.
- A form the author is still editing must not be collecting real answers. Keep an explicit published state and a preview mode that does not write a submission.
- A submission rejected by the server must return the person to the form with their typed answers intact, not to an empty one.

## Testing

Exercise the feature end to end in the running application. Cover every edge case
above, then run the existing test suite and confirm nothing regressed.

## Acceptance Criteria

- [ ] An admin adds, reorders, retypes, and removes fields and publishes the result without a code change.
- [ ] Every builder rule is enforced on the server at submission time.
- [ ] Field keys are stable and stored answers survive label and ordering changes.
- [ ] Submissions made under an earlier version still render and export correctly.
- [ ] Public form endpoints are rate limited and spam screened.
- [ ] A file submitted through a public form is restricted to the same types and sizes as any other upload in the app.
- [ ] A failed submission returns the person's answers rather than an empty form.
- [ ] The feature matches the existing design system.
- [ ] No existing functionality is broken.

## Adaptation Rules

- Match the existing design system. Do not introduce a new colour palette,
  spacing scale, or component library.
- Reuse existing components and utilities wherever they fit.
- Follow the naming, file layout, and code style already present.
- Do not upgrade, replace, or remove existing dependencies to make this
  feature fit. Adapt the feature to the app, not the app to the feature.
- Do not break existing functionality. If a change is genuinely required in
  existing code, make the smallest one that works and say so.
- If something in these instructions conflicts with how the application is
  built, follow the application and explain the deviation.

## Final Verification

Before you report the work as done:

1. Re-read the acceptance criteria above and check each one against what you
   actually built.
2. Run the application and exercise the feature end to end.
3. Run the existing test suite and confirm you have broken nothing.
4. Check the feature on mobile, tablet, and desktop widths.
5. Check keyboard navigation and focus handling.
6. Summarize what changed: files added, files modified, and anything you
   deliberately did differently because of how this application is built.

If any acceptance criterion is unmet, fix it before reporting completion.