# Persistent View Preferences

## Objective

Remember how each user arranged a screen instead of resetting it every visit.

Per-user persistence of sort order, visible columns, filters, and layout choices, restored on return.

## 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. List every view-level choice the app currently forgets: sort, column visibility and order, filters, density, grouping, page size.
2. Decide for each whether it belongs to the device, the account, or the workspace, and be consistent. A column layout is usually account-wide; a sidebar width is usually device-local.
3. Restore preferences before the view renders, so the user never sees the default layout flash into their own.
4. Version the stored shape and discard or migrate anything that no longer matches the current columns and filters.
5. Do not persist transient state such as an open row, a search query typed once, or a selected checkbox. Restoring those is confusing, not helpful.

## 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

- A preference referencing a deleted column or a filter the user has lost access to must be dropped, not applied.
- Signing in must not overwrite newer server preferences with stale local state left over from a signed-out session.
- Two tabs open on the same view must not fight over the stored value.
- Every persisted view needs a visible reset that returns it to defaults.
- In a multi-tenant app, one workspace's layout must not leak into another.
- A user with no stored preferences must get sensible defaults, not an empty layout.

## 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

- [ ] Sort, filters, columns, and layout survive a reload and a new session.
- [ ] Each preference has a documented scope: device, account, or workspace.
- [ ] The saved layout is applied before first paint, with no visible reset.
- [ ] Preferences referencing removed columns or filters are discarded cleanly.
- [ ] Every view offers a reset to defaults.
- [ ] 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.