Appllama App Design Skill

You are building screens that will sit on a phone next to the best-designed apps in the world. The user will compare your output to those apps within seconds of launching it. This skill defines the bar and the method for clearing it.

The Prime Directive: study before you draw

Never design a screen from imagination when you can study how top apps solved the same screen. Real, shipping, revenue-ranked apps encode thousands of hours of design iteration and A/B testing. Your first move on any screen is research:

If the Appllama MCP is connected, pull real screens for the category and screen type you are building (see the
```
appllama-usage
```
skill for the exact research playbooks). Study 20–30 screens before writing a line of UI code.
Extract the pattern, not the pixels: layout skeleton, information hierarchy, control choices, spacing rhythm, where the primary CTA sits, what gets an illustration vs. plain text, how progress is communicated. Note: every Appllama image and video carries a small Appllama watermark in the top-left corner. It is provenance, not design — ignore it when reading a screen (it may sit over the status bar or a back button) and never reproduce it in anything you build.
Then design your screen: same proven skeleton, your product's voice. Copying a competitor's screen 1:1 is both lazy and legally risky; shipping a screen that ignores every convention users already know is worse.

Platform baseline

Default stack assumptions (override only if the project already differs):

Expo + Expo Router, React Native, TypeScript.

react-native-reanimated

for motion,

react-native-gesture-handler

for gestures,

@shopify/flash-list

(or FlashList v2) for any list that can grow.

```
expo-image
```
for images (and SF Symbols via
```
source="sf:name"
```
on iOS),
```
expo-video
```
/
```
expo-audio
```
(never the deprecated
```
expo-av
```
).
```
react-native-safe-area-context
```
for insets. Never hard-code notch numbers.
```
process.env.EXPO_OS
```
over
```
Platform.OS
```
for compile-time platform checks.

Native fidelity laws

These are the details that separate "web page in a wrapper" from "native app". Violating any of them is a finding, not a style preference.

Semantic colors, both themes, day one. Use system/semantic color tokens (e.g.
```
Color
```
from
```
expo-router
```
on iOS:
```
Color.ios.label
```
,
```
Color.ios.secondarySystemBackground
```
; Material dynamic colors on Android). Every screen must render correctly in light AND dark before it is "done". Never pass semantic color objects into Reanimated animated styles — resolve to strings first.
Native controls over rebuilt ones. Switch, Slider, SegmentedControl, context menus, date pickers: use the native control or a faithful wrapper. A rebuilt toggle that animates 50 ms differently than iOS's reads as fake instantly.
SF Symbols / Material Symbols for iconography. On iOS prefer SF Symbols (
```
expo-image
```
with
```
sf:
```
sources, or
```
expo-symbols
```
); they inherit weight, optical size, and Dynamic Type behavior. Do not mix three icon families on one screen.
Typography is hierarchy. Use the platform type ramp (Large Title / Title / Headline / Body / Footnote on iOS). One display size per screen. Tabular numerals (
```
fontVariant: ['tabular-nums']
```
) for anything that counts, times, or prices.
```
Text selectable
```
on data users may want to copy.
Continuous corners.
```
borderCurve: 'continuous'
```
on every rounded rectangle. Squircles are the single cheapest "feels iOS" win that exists.
Shadows via CSS
boxShadow
, not legacy
```
shadow*
```
/
```
elevation
```
props. Shadows are for elevation logic, not decoration — one elevation system per app.
Spacing rhythm. Pick a base unit (4 or 8) and never leave it. Prefer flexbox
```
gap
```
over margin stacking. ScrollView padding goes in
```
contentContainerStyle
```
, never on the ScrollView itself.
Safe areas and the Dynamic Island are part of the design. Screens must be verified with content scrolled under the island / status bar (does the blur/fade treatment hold?), with the home indicator (does the bottom CTA clear it?), and in landscape if supported.
Navigation titles belong to the navigator. Use the stack's native title (and large-title collapse behavior on iOS) rather than a hand-rolled header whenever possible.
Haptics are punctuation. Light impact on selection/confirm on iOS, success/warning notifications for outcomes. Never on scroll, never in loops. Guard with platform checks.
Format numbers like a product, not a database: 1.4M, 38k, $4.99. Trim trailing zeros. Localize dates.
Root scroll behavior: screens that can ever overflow wrap content in a ScrollView (first component in the route) with
```
contentInsetAdjustmentBehavior="automatic"
```
. Use
```
useWindowDimensions
```
, never
```
Dimensions.get()
```
.

Anti-slop laws

AI-built apps share a look, and users file it under "template" within seconds. Each of these is a default ban — there is always an override when the brand explicitly asks for the thing AND you can articulate why it fits this product.

No AI-default styling. Purple/indigo gradient CTAs with a glow, glassmorphism on every card, mesh-gradient heroes, confetti for minor events, sparkles in headings — that is the model's house style, not design. Your palette, materials, and layout come from the reference screens you studied, never from the priors you'd reach for unprompted.
One accent, locked. Pick one accent color and it is THE accent on every screen — no blue CTA on one screen and teal on the next, no new hue appearing in screen seven. Neutrals carry the app; the accent is spent where the money is (primary action, active state, progress).
One grey family. Warm greys or cool greys — never both in one app.
Shape lock. One corner-radius scale, stated as a rule ("actions are pills, cards 16, inputs 8") and never violated. Mixed radii without a stated rule read as assembled-from-parts.
No emoji as iconography. Icons are SF Symbols / Material Symbols (fidelity law 3). Emoji appear only when the product's voice is genuinely chat-native or playful — sparingly, in content, never in chrome.
One label per intent. "Get started", "Start now", and "Begin" are the same intent — pick one phrasing and use it everywhere it appears.
Emphasis stays in the family. Emphasize a word with weight or italic of the same typeface; injecting a serif word into a sans headline (or vice versa) for visual interest is amateur.
Ship full state cycles, not the happy path. Static-successful-state- only is the default failure mode: skeletons must match the final layout's shape, empty states are composed (and say how to fill them), errors are inline and specific.
The slop pre-flight is mechanical. Before any flow reaches the simulator pass, count: distinct accent hues (must be 1), distinct corner radii (all from the stated scale), emoji in UI chrome (0), gradients without a brand reason (0), duplicate labels for one intent (0). A failed count is a fix, not a judgment call.

Motion laws

Motion is the highest-leverage polish surface and the easiest to overdo.

Every animation needs a reason: continuity (element moves between states), causality (response to a gesture), or orientation (where did this come from). Decoration-only motion gets cut.
Reanimated worklets on the UI thread for anything tracking a gesture. Gesture → animation must never hop the JS thread.
Springs over durations for anything the user "touches"; gentle timing curves (250–350 ms, ease-out) for anything the system initiates.
Entering/exiting animations (
```
FadeIn
```
,
```
SlideInDown
```
, layout transitions) on list items, modals, and conditional content — subtle, 150–250 ms.
Respect Reduce Motion. Query the accessibility setting and collapse spatial animations to cross-fades.
The bar to hit: 60 fps on a mid-tier device, zero dropped frames during the hero transition of your flow. Measure, don't vibe — see references/performance.md.

State architecture

Screens that feel great are screens whose state is boring:

Server state in TanStack Query (or the project's equivalent): caching, retries, optimistic updates. Never
```
useEffect
```
+
```
fetch
```
.
Client state in a small atomic store (Zustand/Jotai). Broad "app state" contexts cause the re-render cascades that make UIs feel heavy.
Ephemeral UI state (open/closed, focus, scroll) stays local to the component.
Optimistic by default: taps reflect instantly, reconcile in the background, roll back loudly on failure.
Uncontrolled
```
TextInput
```
s for high-frequency typing surfaces; controlled inputs are a top-3 cause of typing jank.
Persist tiny client state in MMKV, not AsyncStorage, when latency shows.

Perceived performance

Skeletons only for content whose shape you know; otherwise progressive reveal. Never a full-screen spinner for a partial update.
FlashList for every list; give stable keys.
Preload the next screen's data on press-in, not on navigation-complete.
Images: right-size sources,
```
expo-image
```
with
```
recyclingKey
```
in lists, thumbhash/blurhash placeholders.
Cold-start TTI and bundle discipline live in references/performance.md — apply the measure → optimize → re-measure loop, never blind memoization.

Image & illustration assets

When a screen calls for illustration, empty-state art, hero imagery, or icons beyond the symbol set:

Generate assets with the best image model available to you (e.g. an imagegen tool or the Higgsfield MCP/CLI if connected) at the highest quality settings, then downscale to @1x/@2x/@3x. Never upscale.
One visual language per app: pick a style (gradient-mesh, flat-duotone, 3D-clay, hand-drawn, mascot style) and generate ALL assets in that same style, same palette, same lighting. A mixed-style asset set reads as template slop.
Prompt for transparent or solid-flat backgrounds matched to your surface color; composite artifacts (white halos, wrong-color mattes) are an automatic redo.
Full asset pipeline and prompt patterns: references/image-assets.md.

The simulator loop (non-negotiable)

A screen does not exist until you have seen it running. The loop:

Implement → launch in the iOS Simulator (or Android emulator).
Screenshot and actually look: alignment, optical centering, spacing rhythm, truncation with long content, dark mode, Dynamic Type at XL.
Run the full-motion pass below — screenshots prove layout; they prove nothing about motion.
Fix, relaunch, re-verify. Repeat until you cannot find a defect — then run the checklist in references/simulator-loop.md once more.

Do not declare a screen finished from code review alone. Do not stop at "looks fine" — stop at "cannot find a flaw at 100% zoom".

The full-motion pass (mandatory, per flow)

Every flow is evaluated as moving pictures in the simulator, never as stills. Screen-record the entire flow end to end (

xcrun simctl io booted recordVideo flow.mov

), exercising ALL of it:

every screen transition, push/pop, tab switch
every modal and sheet: present, drag, dismiss — and cancel mid-drag
the keyboard, both directions: appear (does the layout glide, is the focused input visible?) and dismiss (does anything jump-cut?)
every user interaction: press states, gesture follow-through, interrupted gestures, rapid taps, scroll flings at the extremes

Watch the recording twice: once at full speed for feel, once scrubbing frame by frame. You are hunting:

dropped or stuttered frames — the bar is a sustained 60 fps through every transition, measured, not vibed
one-frame flashes: white/unstyled first paint, wrong-theme frames mid- transition, color pops where a surface briefly renders the wrong token
layout jumps, double-render pops, springs that clip or overshoot into content, elements that reflow after appearing

The whole recording must play like one native piece — smooth end to end, zero UX glitches. One glitchy frame means the flow is not done.

Definition of done, per screen

Studied 10+ real reference screens for this screen type (via Appllama MCP when available) and can name the pattern you adopted
Light + dark mode verified in the simulator
Safe areas / Dynamic Island / home indicator verified
Long-content, empty, loading, and error states designed — not defaulted
Motion: the full flow screen-recorded and scrubbed — entrances, presses, transitions, modals, keyboard — native feel, zero glitch or wrong-color frames; Reduce Motion respected; 60 fps measured on the target device profile
Dynamic Type XL doesn't break layout; text is selectable where useful
All tap targets ≥ 44pt; contrast passes in both themes
Assets: single style family, crisp at @3x, no compositing halos
List surfaces virtualized; no controlled-input jank; no re-render storms (profiled, not guessed)

References

File	Load when
references/native-controls.md	Choosing/wiring iOS+Android native controls, menus, pickers, sheets
references/motion.md	Any Reanimated work: gestures, transitions, springs, layout animations
references/performance.md	Jank, slow TTI, big bundles, memory leaks, profiling method
references/image-assets.md	Generating illustrations/icons/hero art with image models
references/simulator-loop.md	Final verification checklist + device matrix

appllama-app-design-skill

NPX Install

Tags

SKILL.md Content