# Card and List View Toggle

## Objective

Let users switch between a visual card view and a compact list without losing context.

Two renderings of the same result set, sharing one query, one selection, and one set of controls.

## 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. Drive both views from a single query and a single result set. The toggle is a rendering choice, not a second data path.
2. Keep search, filters, sort, selection, and pagination identical across views. Switching must not clear a filter or reset the page.
3. Give every row action a card equivalent and every card action a row equivalent. If an action exists in only one view, users will not find it.
4. Switch without refetching data you already have, and without a flash of empty state on the way.
5. Persisting the chosen view is owned by Persistent View Preferences; use it rather than adding another storage mechanism.

## 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

- Page size that suits a list is usually wrong for cards — if it differs, changing view must keep the user looking at the same records, not the same page number.
- Selection must survive the switch, including selections scrolled out of view.
- The empty, loading, and error states need a treatment in both views, not just the default one.
- Both views must enforce the same permissions — a card must not reveal a field the list hides.
- Cards without an image need a defined placeholder, or the grid collapses into ragged rows.
- The toggle itself must be keyboard-operable and announce the current view, not just show a highlighted icon.

## 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

- [ ] Switching views issues no additional data request and shows no flicker.
- [ ] Search, filters, sort, selection, and position in the result set are preserved.
- [ ] Every action is available in both views.
- [ ] Empty, loading, and error states exist for both renderings.
- [ ] The two views expose exactly the same fields under the same permissions.
- [ ] The chosen view is persisted through Persistent View Preferences.
- [ ] 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.