What to log

What to log in React Native — event taxonomy and minimum instrumentation for error monitoring and crash reporting

Always know who, which build, which screen, and what happened. Prefer stable event names over free-form sentences alone.

Levels

Level	Use for
`log` (info)	Milestones — screen opened, checkout started, order confirmed
`warn`	Recoverable weirdness — slow API, retry, empty list after success
`error`	Failed user outcomes — even if you catch the exception yourself

Always attach

userId via TraceRN.setUser
release + environment in TraceRN.init
screen via trackScreen or breadcrumb data
A stable event key in the message or extra (e.g. payment.failed)

Event families

Lifecycle

app.opened
screen.viewed (or rely on trackScreen)
auth.signed_in / auth.signed_out

Network

Auto fetch breadcrumbs for requests
Optional slowNetworkThresholdMs in init for slow-fetch warnings
Custom: api.slow, retry.exhausted, offline.queued

Core product flows

checkout.started → payment.failed / order.confirmed
search.submitted, filter.applied
upload.started / upload.failed

Data / UI

list.empty
form.validation_failed
image.load_failed

Minimum viable instrumentation

javascript

import { TraceRN } from "tracern-sdk";

TraceRN.init({
  apiKey: "trn_live_xxxxxxxx",
  environment: __DEV__ ? "dev" : "production",
  release: "1.4.2",
  enableAutoErrorCapture: true,
  enableAutoBreadcrumbs: true,
  enableSessionHeartbeat: true,
  slowNetworkThresholdMs: 3000,
});

TraceRN.setUser(user.id);
TraceRN.trackScreen("Home");

// Milestone
TraceRN.log("checkout.started", { cartSize: cart.items.length, screen: "Checkout" });

// Failed outcome (no throw required)
TraceRN.error(new Error("payment.failed"), {
  event: "payment.failed",
  orderId,
  reason: "card_declined",
});

Checklist

Init with release + environment
setUser after login
trackScreen on every navigation
One info log at the start of each critical flow
One error log for each failed user-visible outcome
Alerts on error spikes for those event names — see alerts

Next: Checkout failed playbook

Last updated · TraceRN docs