Device Testing Presets
Give every tester the same named conditions instead of whatever their laptop does.
What it adds
Named presets bundling viewport, pixel ratio, pointer type, safe-area insets, network speed, and CPU throttling for repeatable testing.
What your agent is told to do
5
What your agent is told to do
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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.
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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.
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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.
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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.
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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.
Edge cases it handles
7
Edge cases it handles
7- 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.
Definition of done
8
Definition of done
8- 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.
Related features
Visual Regression Testing
Visual Regression Testing
Catch unintended visual changes before they reach users, not after.
What it does
An automated comparison of rendered screenshots against approved baselines, run on every change.
How it works
- 1 Identify the surfaces where a silent visual change would actually hurt — the shared components, the pricing table, the checkout, the dashboard — and capture those rather than screenshotting every route in the app.
- 2 Freeze everything that varies between runs before capturing: load fonts and wait for them, fix the clock to a known instant, disable animations and transitions, and render from seeded fixtures rather than live data.
- 3 Capture each surface in every theme and at every viewport the app claims to support, and label each capture with that combination so a diff says exactly which one moved.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/visual-regression-testing
UX Edge-Case Checklist
UX Edge-Case Checklist
Make every UI feature state what it does when things go wrong before it counts as done.
What it does
A required list of non-happy-path behaviours — failure, empty, loading, offline, permission, mobile, and accessibility — answered per feature.
How it works
- 1 Attach the checklist to the point where work is proposed and to the point where it is reviewed, so the answers exist before the feature is built rather than being reconstructed afterwards.
- 2 Require a concrete answer for each category: what the empty state says and what it offers, what appears while data is loading, what the user sees when the request fails, and what a user without permission gets instead.
- 3 Make each answer an outcome someone else could verify. A feature that says errors are handled has not answered; one that says a failed save keeps the form open with the values intact and a retry has.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/ux-edge-case-checklist
Theme Acceptance Criteria
Theme Acceptance Criteria
Set the bar every theme has to clear before it ships to anyone.
What it does
A release gate for light, dark, branded, and customer-supplied themes, covering contrast, first paint, tokens, and print.
How it works
- 1 Write the criteria against the theme layer, not against individual screens. The question is whether a set of token values is fit to ship, and the answer should not require walking every page by hand.
- 2 Require measured contrast for text, icons, borders, focus rings, and disabled content in every interactive state — resting, hover, focus, active, and selected — because a palette that passes at rest often fails on hover.
- 3 Cover the surfaces that sit outside the component library: chart series and their gridlines, map and image overlays, embedded documents, illustrations, and any asset shipped as a fixed-colour file that will not follow the theme.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/theme-acceptance-criteria
How it works
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Copy the link
Grab the Markdown instruction URL for this feature.
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Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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It inspects, then implements
Your agent reads your existing app first, then adds the feature to fit it.
Works with your stack
These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.
Need it tighter than that? Customize the feature and tell it exactly what you're running.