Reproduction for sentry-javascript#19815

sentry-javascript/19815/README.md

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+# Reproduction for sentry-javascript#19815
+
+**Issue:** https://github.com/getsentry/sentry-javascript/issues/19815
+
+## Description
+
+When tracing is disabled (no `tracesSampleRate` set), all errors from different
+requests are assigned the **same** `traceId`. Without an active span per request,
+the SDK never creates a fresh propagation context for each incoming request, so
+every event ends up on the same static trace.
+
+## Steps to Reproduce
+
+1. Install dependencies:
+   ```bash
+   npm install
+   ```
+
+2. (Optional) Set your Sentry DSN to also see events in Sentry UI:
+   ```bash
+   export SENTRY_DSN=https://<key>@sentry.io/<project>
+   ```
+
+3. Run the automated test (starts the server, fires 5 requests, then exits):
+   ```bash
+   bash test.sh
+   ```
+
+   Or run the server manually and send requests yourself:
+   ```bash
+   npm start
+   # in another terminal:
+   curl http://localhost:3000
+   curl http://localhost:3000
+   curl http://localhost:3000
+   ```
+
+## Expected Behavior
+
+Each request produces a **unique** `traceId`, so unrelated errors are not
+grouped into the same trace.
+
+## Actual Behavior
+
+All requests share the same `traceId`. Example output:
+
+```
+[request #1] propagation traceId: e551c9b4398346c88486608a44c0a2a2
+[request #2] propagation traceId: e551c9b4398346c88486608a44c0a2a2
+[request #3] propagation traceId: e551c9b4398346c88486608a44c0a2a2
+[request #4] propagation traceId: e551c9b4398346c88486608a44c0a2a2
+[request #5] propagation traceId: e551c9b4398346c88486608a44c0a2a2
+```
+
+This creates a false impression in Sentry that unrelated errors from different
+requests belong to the same execution flow.
+
+## Environment
+
+- Node.js: v22.15.0
+- @sentry/node: 10.43.0
+- express: ^5.2.1

sentry-javascript/19815/app.js

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+import * as Sentry from '@sentry/node';
+import express from 'express';
+
+const app = express();
+
+let requestCount = 0;
+
+app.get('/', async (_req, res) => {
+  requestCount++;
+  const reqNum = requestCount;
+
+  // Capture the current trace context before captureException
+  const scope = Sentry.getCurrentScope();
+  const propagationContext = scope.getPropagationContext();
+  console.log(`[request #${reqNum}] propagation traceId: ${propagationContext.traceId}`);
+
+  Sentry.captureException(new Error(`Test Error from request #${reqNum}`));
+
+  res.end(`ok (request #${reqNum})\n`);
+});
+
+const server = app.listen(3000, () => {
+  console.log('App listening on port 3000');
+  console.log('');
+  console.log('Bug: All requests share the same traceId when tracing is disabled.');
+  console.log('Each request should produce a different traceId.');
+  console.log('');
+  console.log('Run: curl http://localhost:3000 several times and observe the trace_id in the output.');
+  console.log('');
+});
+
+// Auto-shutdown after 30 seconds to simplify testing
+setTimeout(() => {
+  server.close();
+  process.exit(0);
+}, 30_000);

sentry-javascript/19815/instrument.js

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+import * as Sentry from '@sentry/node';
+
+Sentry.init({
+  // Set your DSN here: export SENTRY_DSN=https://...
+  dsn: process.env.SENTRY_DSN,
+  // Tracing is intentionally disabled (no tracesSampleRate)
+  beforeSend(event) {
+    const traceId = event.contexts?.trace?.trace_id;
+    console.log(`[beforeSend] event type: error | trace_id: ${traceId}`);
+    return event;
+  },
+  beforeSendTransaction(event) {
+    const traceId = event.contexts?.trace?.trace_id;
+    console.log(`[beforeSend] event type: transaction | trace_id: ${traceId}`);
+    return event;
+  },
+});

sentry-javascript/19815/package.json

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+{
+  "name": "sentry-repro-19815",
+  "version": "1.0.0",
+  "description": "Reproduction for sentry-javascript#19815: All errors assigned to same trace when tracing is disabled",
+  "type": "module",
+  "scripts": {
+    "start": "node --import ./instrument.js app.js"
+  },
+  "dependencies": {
+    "@sentry/node": "10.43.0",
+    "express": "^5.2.1"
+  }
+}

sentry-javascript/19815/test.sh

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+#!/usr/bin/env bash
+# Automated test: starts the server, fires 5 requests, and prints the trace IDs.
+# All trace IDs should be the same (the bug), but each should be unique (the fix).
+
+set -e
+
+echo "Starting server..."
+node --import ./instrument.js app.js &
+SERVER_PID=$!
+
+# Wait for server to be ready
+sleep 2
+
+echo ""
+echo "Sending 5 requests..."
+for i in 1 2 3 4 5; do
+  curl -s http://localhost:3000 > /dev/null
+  sleep 0.2
+done
+
+echo ""
+echo "Waiting for events to flush..."
+sleep 1
+
+kill $SERVER_PID 2>/dev/null || true
+echo "Done."