cross-platform-error-handlinglisted

# Cross-Platform Error Handling Patterns for centralized error capture, user-appropriate messaging, and observability across web and mobile clients. ## When to use - Inconsistent error UX across platforms - Unhandled promise rejections or crash reports - Adding global error boundary/handler ## When not to use - Server-side API error design (use `api-and-interface-design`) - Single-platform app with existing mature pattern (extend, don't rewrite) ## Architecture ``` Error occurs → classify (network/auth/validation/unknown) → log (structured, no PII) → user message (actionable, localized) → optional retry/report ``` ## Platform patterns | Platform | Mechanism | |----------|-----------| | React web | Error boundary + window `unhandledrejection` | | React Native | Global handler + native crash reporting SDK | | Next.js | `error.tsx` boundaries + server action error mapping | ## User messaging rules - **Network** — "Check connection" + retry - **Auth** — redirect to login; no token details - **Validation** — field-level hints - **Unknown** — generic message + support/ref ID; log details server-side ## Checklist - [ ] Central error type taxonomy (shared package if monorepo) - [ ] No stack traces shown to end users - [ ] Correlation ID in user-facing error when support needed - [ ] Regression test for at least one error path per platform - [ ] Offline mode handled where applicable