@cphtech-dk/expo-crash-capture

Next-launch native crash capture for Expo apps. Reads the OS's own record of why the process last exited — Android's ApplicationExitInfo, iOS's MetricKit — since neither platform gives an app any hook that runs during a native (non-JS) crash.

This is a separate package from @cphtech-dk/app-monitor on purpose: the SDK depends on neither react-native nor any expo-* package (see ADR-0007), so native crash capture has to be something a consumer opts into, not something the SDK pulls in for everyone.

Install

bun add @cphtech-dk/expo-crash-capture
npx expo prebuild

Requires a dev client or production build — this is native code, so it is not available in Expo Go.

Wiring it into @cphtech-dk/app-monitor

Pass a loader that imports this package by its literal name:

import { init } from "@cphtech-dk/app-monitor/native";

init({
  endpoint: "...",
  apiKey: "...",
  nativeCrashReader: () => import("@cphtech-dk/expo-crash-capture"),
});

That literal specifier matters: Metro (React Native's bundler) only resolves import() calls whose argument it can see as a string at bundle time. It cannot resolve one built from string concatenation or passed as a variable — so init()'s built-in fallback, which builds the specifier from parts to stay polite to other bundlers, silently finds nothing under Metro even when this package is installed. nativeCrashReader is not an optional tuning knob; on React Native it is the difference between this package actually being used and init() quietly no-op'ing every launch. See @cphtech-dk/app-monitor's NativeConfig.nativeCrashReader doc comment and ADR-0011 for the full story.

API

import { getLastExitReasons } from "@cphtech-dk/expo-crash-capture";

const records = await getLastExitReasons();

Resolves to [] on Expo Go, on iOS without MetricKit, on Android below API 30 (Android 11), or if nothing crashed since the last call — never rejects. Each call reports only records newer than the last one it already returned (tracked in SharedPreferences / UserDefaults), so calling it more than once — e.g. once from @cphtech-dk/app-monitor and once from the host app — does not duplicate reports.

See src/types.ts for CrashRecord.

On Android 12+ a native crash's trace is the OS's protobuf tombstone, not text. The module decodes it (TombstoneProto.kt — signal, cause, abort message, the crashing thread's top frames; memory dumps and the memory map are skipped without being read into memory) and renders it in the shape debuggerd logs, with topFrame = SIGNAME lib.so Symbol so one crash site stays one group. Text traces (Android 11, JVM crashes, ANRs) are passed through as before.