# Device Testing Presets

## Objective

Give every tester the same named conditions instead of whatever their laptop does.

Named presets bundling viewport, pixel ratio, pointer type, safe-area insets, network speed, and CPU throttling for repeatable testing.

## 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. Define a small set of named presets that each bundle a viewport, pixel ratio, pointer type, safe-area insets, network profile, and CPU throttle, so a defect can be reported as a preset name rather than a paragraph of settings.
2. Include at least one deliberately hostile preset with a slow network and a throttled processor, because loading states, skeletons, and timeout handling are invisible on a fast machine and are exactly what breaks for real users.
3. Include presets that exercise a touch pointer and a device with safe-area insets, so hit targets, hover-only affordances, and content trapped under a home indicator are caught rather than assumed.
4. Require a preset to cover a keyboard appearing and an orientation change during a flow, not merely at its start, since both resize the viewport while state is already on screen.
5. Version the presets with the QA documentation and change them in the same commit, and state clearly that these presets do not replace testing on real hardware. Which viewports each flow must pass is owned by the Responsive QA Matrix; this brief owns the reproducible conditions themselves.

## 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

- An emulated device is not the device — touch latency, real font rendering, memory pressure, and browser-specific quirks only appear on hardware, so presets must be presented as a first pass rather than as sufficient coverage.
- Without a slow-network and throttled-CPU preset, nobody ever sees the loading state, the request timeout, or the layout shift that real users on a poor connection see every time.
- The on-screen keyboard and a rotation mid-flow both change the usable viewport while a dialog or a form is already open, and testing only from a fresh load in each orientation misses the resulting clipping and lost scroll position.
- Presets that drift away from the QA documentation produce results nobody can reproduce, so the two must move together and each preset must be named and dated.
- A preset that sets a viewport but leaves the pointer as a mouse will report hover states working on a device that has no hover at all.
- Throttling that is applied inconsistently between runs makes performance observations meaningless; the profile must be fixed and stated rather than approximate.
- Presets accumulate for devices no longer in the support list, so retiring one has to be as routine as adding 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

- [ ] Each preset has a name and specifies viewport, pixel ratio, pointer type, safe-area insets, network profile, and CPU throttle.
- [ ] At least one preset applies a slow network and a reduced CPU, and loading and timeout behaviour is verified under it.
- [ ] At least one preset uses a touch pointer and non-zero safe-area insets.
- [ ] Presets cover a keyboard appearing and an orientation change occurring during a flow, not only at its start.
- [ ] Preset definitions live with the QA documentation and are updated in the same change.
- [ ] The documentation states which findings require real hardware and are out of scope for the presets.
- [ ] 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.