| name | platform-engineering |
| description | Cross-platform development rulebook covering security, architecture, and performance for SPA, PWA, mobile (iOS/Android), and desktop (Electron/Tauri) applications. MUST/DO/DON'T framework with real-world incident references and platform-specific guidance. TRIGGER WHEN: reviewing or building cross-platform apps, checking security posture, validating architecture decisions, optimizing performance, or auditing code against industry standards (OWASP, Core Web Vitals, OAuth 2.1). DO NOT TRIGGER WHEN: the task is purely about UI design, copywriting, or business logic unrelated to platform engineering concerns.
|
Cross-Platform Development Rulebook
Three pillars govern every application you ship -- Security, Architecture, and Performance. Each rule is tagged with severity (MUST/DO/DON'T) and platform applicability.
Quick Platform Decision Matrix
| Concern | SPA | PWA | Mobile | Electron | Tauri |
|---|
| Auth token storage | JS memory + httpOnly cookies | JS memory + httpOnly cookies | Platform Keychain/Keystore | OS credential store | OS credential store |
| OAuth flow | Auth Code + PKCE | Auth Code + PKCE | System browser + PKCE | Standard PKCE | Standard PKCE |
| XSS impact | Session hijack | + persistent SW hijack | WebView bridge access | XSS to RCE | Limited to web context |
| CSP | Critical | Critical | WebViews only | Critical | Relevant |
| Offline strategy | Optional | IndexedDB + Cache API + SW | Room/CoreData + sync queue | Optional | Optional |
| Bundle target | <170KB compressed JS | <170KB compressed JS | <20MB APK/IPA | 80-150MB (Chromium) | <10MB total |
| API style | REST or GraphQL | REST (SW caching) | GraphQL (fewer round-trips) | REST (server-side aggregation) | REST |
| State management | Zustand/Redux + TanStack Query | IndexedDB + Cache API | ViewModel+StateFlow / SwiftUI | IPC + context isolation | Rust invoke commands |
When to Load References
- Security review or audit: Load
server-validation, auth-tokens, passkeys-webauthn, api-security, xss-csp, secrets-management, platform-security
- Architecture decisions: Load
client-server-architecture, api-design, offline-first, infrastructure
- Performance optimization: Load
frontend-performance, backend-and-platform-performance
- Full platform review: Load all 13 references
Reference Materials
Security (Part 1)
- server-validation.md -- Server-side validation rules, trust boundaries, real-world bypass incidents
- auth-tokens.md -- Token storage per platform, OAuth 2.1 flows, JWT best practices, secure storage APIs
- passkeys-webauthn.md -- WebAuthn Level 3 / passkey patterns, server-side verification, cross-platform support, cloned-authenticator detection
- api-security.md -- Endpoint auth, rate limiting, CORS, OWASP API risks, Peloton/Parler case studies
- xss-csp.md -- XSS severity by platform, CSP directives, anti-CSRF, sanitization, British Airways incident
- secrets-management.md -- Secret exposure risks, environment variables, vault services, GitGuardian stats
- platform-security.md -- Mobile (Keychain/Keystore, cert pinning), Electron (nodeIntegration, contextIsolation, sandbox), Tauri (deny-by-default), PWA (service worker scope, Cache API risks), security headers matrix
Architecture (Part 2)
- client-server-architecture.md -- Thin client principle, BFF pattern, server-authoritative design
- api-design.md -- REST vs GraphQL trade-offs by platform, pagination strategies, state management per platform
- offline-first.md -- Conflict resolution strategies (LWW, CRDTs, OT), optimistic UI, sync patterns
- infrastructure.md -- Monolith-first principle, database access patterns, CI/CD pipelines per platform, observability, feature flag lifecycle
Performance (Part 3)
- frontend-performance.md -- Bundle size optimization, image formats and responsive loading, Core Web Vitals (LCP, INP, CLS) with business impact data
- backend-and-platform-performance.md -- API/DB performance (pagination, indexing, connection pooling), mobile battery/memory, SSR/SSG/ISR rendering strategies, CDN caching patterns
