Mobile observability goes far beyond crash reporting. A mature architecture connects five signal classes — crashes, structured logs, distributed traces, API failure telemetry, and business events — using shared correlation identifiers (session ID, flow ID, trace context headers) across mobile clients and backend services. The post covers a four-layer model (instrumentation, correlation, backend propagation, analysis), a Kotlin OkHttp interceptor example for attaching request context, common misconceptions (crash-free rate ≠ healthy app, backend traces don't explain client-side failures), key architectural trade-offs (privacy vs. detail, fidelity vs. cost, real-time vs. battery), and a practical checklist. A real-world case study illustrates how joining mobile API failure events, backend payment traces, and product analytics revealed a post-payment polling bug invisible to any single dashboard.
