analyzing-llm-rationale: Skill for Claude Code

OTel Expo Style

Preserve existing runtime guards. If the app avoids native SDKs in Expo Go or an unsupported runtime branch, initialize OTel only inside the supported branch.

const isExpoGo = process.env.EXPO_PUBLIC_RUNTIME === "expo-go";

if (!isExpoGo) {
  initObservability();
  Sentry.init({ dsn: process.env.EXPO_PUBLIC_SENTRY_DSN });
}

registerRootComponent(App);

In supported builds, call initObservability() before Sentry and before app registration/user code.

SDK Shape

Use native OTel JS APIs and browser/mobile-compatible providers/exporters. Do not create recordCounter, sendSuperlogSpan, or tracking-specific helper files.

export const tracer = trace.getTracer("mugline.mobile");
export const meter = metrics.getMeter("mugline.mobile");
export const ordersSubmitted = meter.createCounter("mug.orders.submitted");

Add automatic fetch/XHR instrumentation when compatible so API calls get spans without wrapping application code.

Product Actions

Wrap low-risk business operations with native active spans.

await tracer.startActiveSpan("mug.order.submit", async (span) => {
  try {
    span.setAttribute("tenant.id", tenantId);
    ordersSubmitted.add(1, { "tenant.id": tenantId, outcome: "success" });
  } catch (error) {
    span.recordException(error as Error);
    span.setStatus({ code: SpanStatusCode.ERROR });
    throw error;
  } finally {
    span.end();
  }
});

Configuration

Inline the endpoint and sl_public_ token directly in the observability module. The token is project-scoped, write-only, and intended to be safe in client bundles. Avoid EXPO_PUBLIC_* env vars for Superlog so the mobile build does not depend on deploy-time configuration.

const SUPERLOG_ENDPOINT = "https://intake.superlog.sh";
const SUPERLOG_PUBLIC_TOKEN = "sl_public_...";
const SERVICE_NAME = "mugline-mobile";

// The token MUST be sent as the `x-api-key` header. Ingest only reads
// `x-api-key` or `Authorization: Bearer <token>`; any other header name 401s.
function superlogHeaders(token: string): Record<string, string> {
  return { "x-api-key": token };
}

const exporter = new OTLPTraceExporter({
  url: `${SUPERLOG_ENDPOINT}/v1/traces`,
  headers: superlogHeaders(SUPERLOG_PUBLIC_TOKEN),
});