# Display Density

## Objective

Let users pick comfortable or compact spacing without breaking the layout.

A density setting that tightens row height, padding, and font size across the app's data surfaces.

## 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. Express spacing as tokens first. If padding is hardcoded across components, extract it before adding the setting.
2. Offer two or three levels, no more. Comfortable and compact cover almost everyone.
3. Apply density consistently to tables, lists, menus, cards, and form rows. A compact table beside a comfortable form looks broken.
4. Apply the stored choice before first paint so rows do not resize under the cursor.
5. Do not shrink touch targets below the accessible minimum in compact mode. Reduce padding and line height, not hit area.

## 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

- Compact mode must not clip descenders or truncate text that fitted before.
- Icons and avatars need their own scale steps; leaving them at full size defeats the compaction.
- Touch devices should default to comfortable regardless of the desktop preference.
- In a multi-tenant app, decide whether density follows the user or the workspace, and say which.
- Row heights used by virtualized lists must be recalculated when density changes, or scrolling will misplace items.
- Density must not change the number of columns or hide content, only the spacing around it.

## 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

- [ ] Density applies uniformly across tables, lists, menus, cards, and forms.
- [ ] The choice persists and is applied before the page renders.
- [ ] Touch targets stay at least 44x44px in every mode.
- [ ] No text is clipped or truncated in compact mode.
- [ ] Virtualized lists measure correctly after a density change.
- [ ] 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.