# Mobile Observability Overview

> Mobile observability - metrics, traces, logs, and events within the constraints of battery, network, and storage. Use when defining what to collect, how to sample, and how to pipe signals to analytics and APM tools.

- Skill: `almasumdev/mobile-observability-overview` (Agent Skill)
- Install (CLI): `npx skillmds@latest add almasumdev/mobile-observability-overview`
- Raw SKILL.md: https://api.skillmd.com/api/skills/almasumdev/mobile-observability-overview/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Data & Analytics
- Author: almasumdev (https://skillmd.com/u/almasumdev)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/almasumdev/mobile-observability-overview

---


# Mobile Observability Overview

## Instructions

Mobile observability is not "backend observability, but smaller". Devices are constrained: battery, flaky networks, storage quotas, privacy boundaries, and the impossibility of hotfixing. Collect what you need, sample aggressively, and never ship a telemetry SDK that costs more than it informs.

### 1. The Four Signals, Mobile-Flavored

| Signal | Why | Constraints |
| --- | --- | --- |
| Metrics | Numeric trends (startup time, crash-free, conversion) | Low volume, aggregate client-side |
| Traces | Causal chain across calls (cold start, feature flow) | Sample heavily; one trace per flow |
| Logs | Event narrative | Expensive to ship; breadcrumbs are preferable |
| Events (analytics) | Product decisions | Deduplicate and batch; respect consent |

### 2. What to Measure

Minimum set every mobile app should emit:

- **Cold start** time to first frame, to first interactive.
- **Warm start** time.
- **Frame drops / jank** on key screens.
- **Network**: p50/p95 latency per endpoint, error rate per endpoint, retry counts.
- **Crash-free sessions / users** (see `crash-reporting-strategy`).
- **ANRs** (Android), **hangs** (iOS).
- **Battery drain** signals via OS tooling; not a per-event metric.
- **Sync**: outbox length, drain success rate, conflict rate.
- **Funnel events**: sign-in started/completed, checkout stages, key feature start/complete.

### 3. Cold Start Budget

- Target **under 2s** to first meaningful paint on mid-range devices.
- Measure with `MetricKit` on iOS and `Macrobenchmark` / `StartupTracing` on Android.
- Budget: every new SDK adds 50-200ms; every synchronous disk read in Application startup adds 20-100ms.

```kotlin
// Android: AppStartup + Firebase Performance
class PerformanceInitializer : Initializer<Unit> {
    override fun create(context: Context) {
        FirebasePerformance.getInstance().isPerformanceCollectionEnabled = true
    }
    override fun dependencies(): List<Class<out Initializer<*>>> = emptyList()
}
```

```swift
// iOS: MetricKit
class MetricsObserver: NSObject, MXMetricManagerSubscriber {
    func didReceive(_ payloads: [MXMetricPayload]) {
        for p in payloads { Metrics.send("launch.time", p.applicationLaunchMetrics?.histogrammedTimeToFirstDraw) }
    }
}
MXMetricManager.shared.add(MetricsObserver.shared)
```

### 4. Tracing

Use tracing for end-to-end flows that span UI, local storage, and network. Typical traces:

- Cold start: process start -> splash -> first screen render.
- Sign-in: tap -> auth API -> token exchange -> first authed screen.
- Checkout: cart -> address -> payment -> confirmation.

Keep per-trace spans shallow (under 20). Sample heavily (5-10% on production, 100% in dev/staging). Attach trace IDs to logs for correlation.

### 5. Logs vs Breadcrumbs

- Ship **breadcrumbs** to the crash reporter; they travel with the next crash.
- Do not stream every log to a backend. It burns battery and bandwidth.
- For debugging in the field, ship a **log export** feature that bundles recent logs with the user's consent and a support ticket.

### 6. Analytics Events

- Maintain a **spec** (JSON schema) for every event: name, required properties, versioning.
- Gate event emission on **consent** where legally required (GDPR, CCPA).
- Deduplicate: retry-safe events carry a client event ID; the pipeline dedupes.
- Batch and flush on:
    - Network available + above threshold N events.
    - App backgrounding (with a short budget).
    - Foreground recovery after offline.

```tsx
// React Native - simple batcher
const queue: AnalyticsEvent[] = [];
function track(event: AnalyticsEvent) {
  queue.push({ ...event, id: uuid(), ts: Date.now() });
  if (queue.length >= 20) flush();
}
AppState.addEventListener('change', (s) => { if (s === 'background') flush(); });
```

### 7. Privacy and Consent

- Never send PII in telemetry. Hash stable IDs; do not send email, name, phone.
- Respect **App Tracking Transparency** on iOS for anything that qualifies as tracking.
- Respect **Play Data Safety** declarations; the label must match what you actually collect.
- Provide in-app **opt-out** for analytics/crash reporting. Persist the choice across reinstalls if legally required (keychain on iOS).
- Do not store telemetry buffers in backups that might sync to iCloud/Drive with PII.

### 8. Sampling and Cost

- Client-side sampling: traces and non-critical metrics at 1-10%. Scale with user base.
- Server-side backstop: pipeline rejects over-quota events to keep costs sane.
- Aggregate on-device where possible (histograms over events) and send summaries.

### 9. Dashboards and Alerts

- One dashboard per release showing: crash-free sessions, key funnel, top endpoints, cold start.
- Alerts tied to SLOs, not raw metrics.
- Release-aware: the alert knows which version is rolling out and compares cohorts.

### 10. Tool Menu

- **Firebase Performance + Crashlytics**: free, baseline.
- **Sentry**: traces + release health + errors + logs.
- **Datadog RUM**, **New Relic Mobile**, **Dynatrace**: enterprise APM.
- **PostHog**, **Amplitude**, **Mixpanel**: product analytics.
- **OpenTelemetry** for mobile: growing; useful if your backend is OTel-native.

Do not stack five SDKs. Inventory every one against privacy labels and startup cost.

### 11. Anti-Patterns

- Logging every function call "just in case". Data volume drowns the signal.
- Streaming real-time logs from production clients. Use breadcrumbs and support bundles.
- Sending full URLs with query strings containing secrets.
- Collecting precise location for analytics. Truncate or avoid.
- Not versioning event schemas. Breaking downstream consumers silently.
- Letting the analytics backlog grow unbounded on disk.

## Checklist

- [ ] Core metrics (cold start, jank, crash-free, network p95) are collected per release.
- [ ] Tracing is set up for critical flows with sane sampling.
- [ ] Analytics events follow a versioned schema with a single spec.
- [ ] Consent gates telemetry where legally required.
- [ ] No PII or secrets travel in telemetry.
- [ ] Breadcrumbs replace always-on log streaming.
- [ ] Event batches flush on backgrounding and on network recovery.
- [ ] Dashboards are release-aware with cohort comparison.
- [ ] Telemetry SDK count is audited against privacy labels.
- [ ] Per-endpoint error and latency signals feed rollout halt criteria.