From 83093bf71bdd432d9cfdfac65fba2c7d6a7079a3 Mon Sep 17 00:00:00 2001
From: JPeer264 <jan.peer@sentry.io>
Date: Thu, 11 Dec 2025 13:39:11 +0100
Subject: [PATCH] fix(cloudflare): Missing events inside waitUntil

---
 .../cloudflare-workers/src/index.ts           | 16 ++++++++-
 .../cloudflare-workers/tests/index.test.ts    | 33 ++++++++++++++++++-
 packages/cloudflare/src/flush.ts              | 16 +++++++--
 3 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/dev-packages/e2e-tests/test-applications/cloudflare-workers/src/index.ts b/dev-packages/e2e-tests/test-applications/cloudflare-workers/src/index.ts
index ab438432a004..a42aed262089 100644
--- a/dev-packages/e2e-tests/test-applications/cloudflare-workers/src/index.ts
+++ b/dev-packages/e2e-tests/test-applications/cloudflare-workers/src/index.ts
@@ -81,7 +81,7 @@ export default Sentry.withSentry(
     },
   }),
   {
-    async fetch(request, env) {
+    async fetch(request, env, ctx) {
       const url = new URL(request.url);
       switch (url.pathname) {
         case '/rpc/throwException':
@@ -96,6 +96,20 @@ export default Sentry.withSentry(
             }
           }
           break;
+        case '/waitUntil':
+          console.log('waitUntil called');
+
+          const longRunningTask = async () => {
+            await new Promise(resolve => setTimeout(resolve, 3000));
+
+            console.log('ʕっ•ᴥ•ʔっ');
+            Sentry.captureException(new Error('ʕノ•ᴥ•ʔノ ︵ ┻━┻'));
+          };
+
+          ctx.waitUntil(longRunningTask());
+
+          return new Response(null, { status: 200 });
+
         case '/throwException':
           throw new Error('To be recorded in Sentry.');
         default:
diff --git a/dev-packages/e2e-tests/test-applications/cloudflare-workers/tests/index.test.ts b/dev-packages/e2e-tests/test-applications/cloudflare-workers/tests/index.test.ts
index 8c09693c81ed..7b674fd7f122 100644
--- a/dev-packages/e2e-tests/test-applications/cloudflare-workers/tests/index.test.ts
+++ b/dev-packages/e2e-tests/test-applications/cloudflare-workers/tests/index.test.ts
@@ -1,6 +1,7 @@
 import { expect, test } from '@playwright/test';
-import { waitForError, waitForRequest } from '@sentry-internal/test-utils';
+import { waitForError, waitForRequest, waitForTransaction } from '@sentry-internal/test-utils';
 import { SDK_VERSION } from '@sentry/cloudflare';
+import { waitForDebugger } from 'inspector';
 import { WebSocket } from 'ws';
 
 test('Index page', async ({ baseURL }) => {
@@ -82,3 +83,33 @@ test('sends user-agent header with SDK name and version in envelope requests', a
     'user-agent': `sentry.javascript.cloudflare/${SDK_VERSION}`,
   });
 });
+
+test('waitUntil', async ({ baseURL }) => {
+  const errorWaiter = waitForError('cloudflare-workers', () => true);
+  const waitUntilSpanWaiter = waitForTransaction('cloudflare-workers', span => span.transaction === 'waitUntil');
+  const httpTransactionWaiter = waitForTransaction(
+    'cloudflare-workers',
+    transactionEvent => transactionEvent.contexts?.trace?.op === 'http.server',
+  );
+
+  const response = await fetch(`${baseURL}/waitUntil`);
+
+  const transactionRequest = await httpTransactionWaiter;
+  const waitUntilSpan = await waitUntilSpanWaiter;
+  const errorEvent = await errorWaiter;
+
+  expect(response.status).toBe(200);
+
+  // All traceIds should be the same
+  expect(transactionRequest.contexts?.trace?.trace_id).toBe(waitUntilSpan.contexts?.trace?.trace_id);
+  expect(transactionRequest.contexts?.trace?.trace_id).toBe(errorEvent.contexts?.trace?.trace_id);
+
+  expect(errorEvent.exception?.values?.[0]?.value).toBe('ʕノ•ᴥ•ʔノ ︵ ┻━┻');
+  expect(errorEvent.breadcrumbs).toStrictEqual(waitUntilSpan.breadcrumbs);
+
+  expect(waitUntilSpan.contexts?.trace?.parent_span_id).toBe(transactionRequest.contexts?.trace?.span_id);
+
+  console.log(JSON.stringify(transactionRequest, null, 2));
+  console.log(JSON.stringify(waitUntilSpan, null, 2));
+  console.log(JSON.stringify(errorEvent, null, 2));
+});
diff --git a/packages/cloudflare/src/flush.ts b/packages/cloudflare/src/flush.ts
index f38c805d0f8b..a6568d81ab46 100644
--- a/packages/cloudflare/src/flush.ts
+++ b/packages/cloudflare/src/flush.ts
@@ -1,4 +1,5 @@
 import type { ExecutionContext } from '@cloudflare/workers-types';
+import { startSpan, withScope } from '@sentry/core';
 
 type FlushLock = {
   readonly ready: Promise<void>;
@@ -22,9 +23,20 @@ export function makeFlushLock(context: ExecutionContext): FlushLock {
   const originalWaitUntil = context.waitUntil.bind(context) as typeof context.waitUntil;
   context.waitUntil = promise => {
     pending++;
+
     return originalWaitUntil(
-      promise.finally(() => {
-        if (--pending === 0) resolveAllDone();
+      // Wrap the promise in a new scope and transaction so spans created inside
+      // waitUntil callbacks are properly isolated from the HTTP request transaction
+      withScope(() =>
+        startSpan({ forceTransaction: true, op: 'cloudflare.wait_until', name: 'wait_until' }, async () => {
+          // By awaiting the promise inside the new scope, all of its continuations
+          // will execute in this isolated scope
+          await promise;
+        }),
+      ).finally(() => {
+        if (--pending === 0) {
+          resolveAllDone();
+        }
       }),
     );
   };