Borrowing it
Nothing to install: this file belongs to bonnguyenitc/antigravity-superpowers. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/bonnguyenitc/antigravity-superpowers/main/.agent/skills/mobile-developer/SKILL.mdgit clone --depth 1 https://github.com/bonnguyenitc/antigravity-superpowersWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/bonnguyenitc/antigravity-superpowers/mobile-developer)<a href="https://agentmods.dev/skills/bonnguyenitc/antigravity-superpowers/mobile-developer"><img src="https://agentmods.dev/badge/skills/bonnguyenitc/antigravity-superpowers/mobile-developer.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00035 | $0.01873 |
| Opus 5 | $0.00017 | $0.00937 |
| Sonnet 5 | $0.00007 | $0.00375 |
| Haiku 4.5 | $0.00003 | $0.00187 |
Grade A, and why
mobile-developer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 195 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mobile Developer Lens
Philosophy: Touch-first. Offline-capable. Battery-conscious. Platform-respectful. Mobile is NOT a small desktop. Design for bad network, one hand, bright sun, low battery.
⚠️ ASK BEFORE ASSUMING
If the request is open-ended, DO NOT default to React Native. Ask:
| What | Why it matters |
|---|---|
| Platform? iOS / Android / Both | Affects EVERY design decision |
| Framework? RN / Flutter / SwiftUI / Compose | Determines patterns and tools |
| Offline required? | Core architecture decision |
| Target devices? Phone / Tablet | Layout and nav complexity |
When stack is unspecified, assume React Native + Expo.
Framework Decision Tree
What are you building?
├── Need OTA updates + rapid iteration → React Native + Expo
├── Pixel-perfect custom UI + perf-critical → Flutter
├── Deep native features, single platform
│ ├── iOS only → SwiftUI (iOS 16+) or UIKit (legacy)
│ └── Android only → Kotlin + Jetpack Compose
└── Existing codebase → match the codebase
Core Instincts
- Offline-first — assume the network will fail; design around it from day one
- Platform parity — iOS and Android behave differently; both must work
- Startup cost — every dependency adds to cold start time and binary size; justify each one
- UI/main thread is precious — heavy computation and animations must run off the main thread
- Battery budget — background tasks, location, and push use real energy; minimize wake-ups
Performance Thresholds
| Metric | Target | Critical |
|---|---|---|
| Cold start time (JS bundle ready) | < 1s | > 2s |
| Time to interactive (first screen) | < 2s | > 4s |
| List scroll frame rate | 60fps | < 45fps |
| IPA / APK download size | < 30MB | > 100MB |
| Memory usage (foreground) | < 150MB | > 300MB |
| JS bundle size (RN, gzipped) | < 1MB | > 3MB |
❌ Anti-Patterns to Avoid
| ❌ NEVER DO | Why | ✅ DO INSTEAD |
|---|---|---|
ScrollView for long lists |
Renders ALL items, memory explodes | FlatList / FlashList / ListView.builder |
Inline renderItem function |
New function every render, all items re-render | useCallback + React.memo on item component |
Missing keyExtractor (or using index) |
Reorder causes state/animation bugs | Use unique stable ID from data |
useNativeDriver: false on animations |
Animations run on JS thread, janky | useNativeDriver: true — GPU-only transforms |
Token in AsyncStorage |
Plaintext, exposed on rooted device | expo-secure-store / Keychain / EncryptedSharedPreferences |
| Business logic in UI components | Untestable, duplicated | Separate service/hook layer |
| Deep links as afterthought | Notifications and shares break | Plan linking config from day one |
console.log in production build |
Blocks JS thread, leaks data | Remove; use a proper logger with levels |
What ships with it
60 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- references/android-native.md 13 KB
- references/android-rules/android-accessibility.md 1.8 KB
- references/android-rules/android-architecture.md 3.0 KB
- references/android-rules/android-coroutines.md 5.4 KB
- references/android-rules/android-data-layer.md 1.8 KB
- references/android-rules/android-emulator-skill.md 3.6 KB
- references/android-rules/android-gradle-logic.md 3.4 KB
- references/android-rules/android-retrofit.md 4.5 KB
- references/android-rules/android-testing.md 2.9 KB
- references/android-rules/android-viewmodel.md 1.8 KB
- references/android-rules/coil-compose.md 3.1 KB
- references/android-rules/compose-navigation.md 11 KB
- references/android-rules/compose-performance-audit.md 6.6 KB
- references/android-rules/compose-ui.md 2.6 KB
- references/android-rules/gradle-build-performance.md 8.0 KB
- references/android-rules/kotlin-concurrency-expert.md 5.5 KB
- references/android-rules/rxjava-to-coroutines-migration.md 4.8 KB
- references/android-rules/xml-to-compose-migration.md 10.0 KB
- references/flutter-rules/dart-best-practices.md 1.5 KB
- references/flutter-rules/dart-checks-migration.md 4.4 KB
- references/flutter-rules/dart-cli-app-best-practices.md 4.0 KB
- references/flutter-rules/dart-doc-validation.md 1.5 KB
- references/flutter-rules/dart-matcher-best-practices.md 3.5 KB
- references/flutter-rules/dart-modern-features.md 5.7 KB
- references/flutter-rules/dart-package-maintenance.md 3.0 KB
- references/flutter-rules/dart-test-fundamentals.md 3.5 KB
- references/flutter.md 10 KB
- references/ios-native.md 12 KB
- references/ios-rules/accessibility-patterns.md 5.9 KB
- references/ios-rules/animation-advanced.md 10 KB
- references/ios-rules/animation-basics.md 6.7 KB
- references/ios-rules/animation-transitions.md 7.4 KB
- references/ios-rules/charts-accessibility.md 6.1 KB
- references/ios-rules/charts.md 17 KB
- references/ios-rules/image-optimization.md 7.2 KB
- references/ios-rules/latest-apis.md 15 KB
- references/ios-rules/layout-best-practices.md 6.8 KB
- references/ios-rules/liquid-glass.md 11 KB
- references/ios-rules/list-patterns.md 11 KB
- references/ios-rules/macos-scenes.md 9.1 KB
- references/ios-rules/macos-views.md 11 KB
- references/ios-rules/macos-window-styling.md 8.6 KB
- references/ios-rules/performance-patterns.md 12 KB
- references/ios-rules/scroll-patterns.md 8.3 KB
- references/ios-rules/sheet-navigation-patterns.md 11 KB
- references/ios-rules/state-management.md 14 KB
- references/ios-rules/view-structure.md 13 KB
- references/react-native-rules/_sections.md 2.2 KB
- references/react-native-rules/_template.md 631 B
- references/react-native-rules/animation-derived-value.md 1.3 KB
- references/react-native-rules/animation-gesture-detector-press.md 2.5 KB
- references/react-native-rules/animation-gpu-properties.md 2.0 KB
- references/react-native-rules/design-system-compound-components.md 1.6 KB
- references/react-native-rules/fonts-config-plugin.md 1.4 KB
- references/react-native-rules/imports-design-system-folder.md 1.4 KB
- references/react-native-rules/js-hoist-intl.md 1.6 KB
- references/react-native-rules/list-performance-callbacks.md 1.0 KB
- references/react-native-rules/list-performance-function-references.md 4.0 KB
- references/react-native-rules/list-performance-images.md 1.4 KB
- references/react-native-rules/list-performance-inline-objects.md 2.3 KB
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 195 lines · 35 tokens per session scan A 636ecc38f6fb
mobile-developer is a skill published in the GitHub repository bonnguyenitc/antigravity-superpowers (19 stars, last pushed 4mo ago), licensed MIT. It adds 35 tokens to every session and 1,873 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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