feat(core)!: Enable span streaming by default

Default clients to the streamed trace lifecycle and automatically install
the required streaming integration in browser and server runtimes.
Explicit static lifecycle configuration remains supported.

BREAKING CHANGE: Spans use the streamed trace lifecycle unless configured otherwise.
Fixes #22344

Co-Authored-By: Cursor <cursoragent@cursor.com>

Author: Lms24

packages/browser/src/sdk.ts

@@ -19,6 +19,7 @@ import { globalHandlersIntegration } from './integrations/globalhandlers';
 import { httpContextIntegration } from './integrations/httpcontext';
 import { linkedErrorsIntegration } from './integrations/linkederrors';
 import { spotlightBrowserIntegration } from './integrations/spotlight';
+import { spanStreamingIntegration } from './integrations/spanstreaming';
 import { defaultStackParser } from './stack-parsers';
 import { makeFetchTransport } from './transports/fetch';
 import { normalizeStringifyValue } from './normalizeStringifyValue';
@@ -110,14 +111,20 @@ export function init(options: BrowserOptions = {}): Client | undefined {
   }
   /*! rollup-include-development-only-end */
 
+  const integrations = getIntegrationsToSetup({
+    integrations: options.integrations,
+    defaultIntegrations,
+  });
+
+  if (options.traceLifecycle !== 'static' && !integrations.some(integration => integration.name === 'SpanStreaming')) {
+    integrations.push(spanStreamingIntegration());
+  }
+
   const clientOptions: BrowserClientOptions = {
     ...options,
     enabled: shouldDisableBecauseIsBrowserExtenstion ? false : options.enabled,
     stackParser: stackParserFromStackParserOptions(options.stackParser || defaultStackParser),
-    integrations: getIntegrationsToSetup({
-      integrations: options.integrations,
-      defaultIntegrations,
-    }),
+    integrations,
     transport: options.transport || makeFetchTransport,
   };
 

packages/browser/test/profiling/UIProfiler.test.ts

@@ -11,6 +11,7 @@ function getBaseOptionsForTraceLifecycle(sendMock: Mock<any>, enableTracing = tr
   return {
     dsn: 'https://public@o.ingest.sentry.io/1',
     ...(enableTracing ? { tracesSampleRate: 1 } : {}),
+    traceLifecycle: 'static',
     profileSessionSampleRate: 1,
     profileLifecycle: 'trace',
     integrations: [Sentry.browserProfilingIntegration()],
@@ -711,6 +712,7 @@ function getBaseOptionsForManualLifecycle(sendMock: Mock<any>, enableTracing = t
   return {
     dsn: 'https://public@o.ingest.sentry.io/1',
     ...(enableTracing ? { tracesSampleRate: 1 } : {}),
+    traceLifecycle: 'static',
     profileSessionSampleRate: 1,
     profileLifecycle: 'manual',
     integrations: [Sentry.browserProfilingIntegration()],

packages/browser/test/profiling/integration.test.ts

@@ -39,6 +39,7 @@ describe('BrowserProfilingIntegration', () => {
     const send = vi.fn().mockImplementation(() => Promise.resolve());
     const client = Sentry.init({
       tracesSampleRate: 1,
+      traceLifecycle: 'static',
       profilesSampleRate: 1,
       environment: 'test-environment',
       dsn: 'https://7fa19397baaf433f919fbe02228d5470@o1137848.ingest.sentry.io/6625302',
@@ -134,6 +135,7 @@ describe('BrowserProfilingIntegration', () => {
       const send = vi.fn().mockResolvedValue(undefined);
       const client = Sentry.init({
         tracesSampleRate: 1,
+        traceLifecycle: 'static',
         profilesSampleRate: 1,
         dsn: 'https://7fa19397baaf433f919fbe02228d5470@o1137848.ingest.sentry.io/6625302',
         transport: _opts => ({

packages/browser/test/sdk.test.ts

@@ -61,6 +61,32 @@ describe('init', () => {
     expect(optionsPassed?.integrations.length).toBeGreaterThan(0);
   });
 
+  it('installs spanStreamingIntegration by default', () => {
+    // @ts-expect-error this is fine for testing
+    const initAndBindSpy = vi.spyOn(SentryCore, 'initAndBind').mockImplementationOnce(() => {});
+    const options = getDefaultBrowserOptions({ dsn: PUBLIC_DSN, defaultIntegrations: undefined });
+
+    init(options);
+
+    const optionsPassed = initAndBindSpy.mock.calls[0]?.[1];
+    expect(optionsPassed?.integrations.some(integration => integration.name === 'SpanStreaming')).toBe(true);
+  });
+
+  it('does not install spanStreamingIntegration when traceLifecycle is static', () => {
+    // @ts-expect-error this is fine for testing
+    const initAndBindSpy = vi.spyOn(SentryCore, 'initAndBind').mockImplementationOnce(() => {});
+    const options = getDefaultBrowserOptions({
+      dsn: PUBLIC_DSN,
+      defaultIntegrations: undefined,
+      traceLifecycle: 'static',
+    });
+
+    init(options);
+
+    const optionsPassed = initAndBindSpy.mock.calls[0]?.[1];
+    expect(optionsPassed?.integrations.some(integration => integration.name === 'SpanStreaming')).toBe(false);
+  });
+
   test("doesn't install default integrations if told not to", () => {
     const DEFAULT_INTEGRATIONS: Integration[] = [
       new MockIntegration('MockIntegration 0.3'),
@@ -73,6 +99,17 @@ describe('init', () => {
     expect(DEFAULT_INTEGRATIONS[1]!.setupOnce as Mock).toHaveBeenCalledTimes(0);
   });
 
+  it('installs spanStreamingIntegration with defaultIntegrations disabled', () => {
+    // @ts-expect-error this is fine for testing
+    const initAndBindSpy = vi.spyOn(SentryCore, 'initAndBind').mockImplementationOnce(() => {});
+    const options = getDefaultBrowserOptions({ dsn: PUBLIC_DSN, defaultIntegrations: false });
+
+    init(options);
+
+    const optionsPassed = initAndBindSpy.mock.calls[0]?.[1];
+    expect(optionsPassed?.integrations.some(integration => integration.name === 'SpanStreaming')).toBe(true);
+  });
+
   it('installs merged default integrations, with overrides provided through options', () => {
     const DEFAULT_INTEGRATIONS = [
       new MockIntegration('MockIntegration 1.1'),

packages/bun/test/init.test.ts

@@ -35,7 +35,7 @@ describe('init()', () => {
 
   describe('integrations', () => {
     it("doesn't install default integrations if told not to", () => {
-      init({ dsn: PUBLIC_DSN, defaultIntegrations: false });
+      init({ dsn: PUBLIC_DSN, defaultIntegrations: false, traceLifecycle: 'static' });
 
       const client = getClient();
 
@@ -132,7 +132,7 @@ describe('init()', () => {
 
   describe('initWithoutDefaultIntegrations()', () => {
     it('installs no default integrations', () => {
-      initWithoutDefaultIntegrations({ dsn: PUBLIC_DSN });
+      initWithoutDefaultIntegrations({ dsn: PUBLIC_DSN, traceLifecycle: 'static' });
 
       const client = getClient();
 
@@ -143,7 +143,11 @@ describe('init()', () => {
     it('still installs user-provided integrations', () => {
       const customIntegration = new MockIntegration('Custom integration');
 
-      initWithoutDefaultIntegrations({ dsn: PUBLIC_DSN, integrations: [customIntegration] });
+      initWithoutDefaultIntegrations({
+        dsn: PUBLIC_DSN,
+        integrations: [customIntegration],
+        traceLifecycle: 'static',
+      });
 
       const client = getClient();
 

packages/bundler-plugins/src/core/sentry/telemetry.ts

@@ -27,6 +27,7 @@ export function createSentryInstance(
     dsn: 'https://4c2bae7d9fbc413e8f7385f55c515d51@o1.ingest.sentry.io/6690737',
 
     tracesSampleRate: 1,
+    traceLifecycle: 'static',
     sampleRate: 1,
 
     release: LIB_VERSION,

packages/cloudflare/test/instrumentations/worker/instrumentEmail.test.ts

@@ -245,6 +245,7 @@ describe('instrumentEmail', () => {
         env => ({
           dsn: env.SENTRY_DSN,
           tracesSampleRate: 1,
+          traceLifecycle: 'static',
           beforeSendTransaction(event) {
             sentryEvent = event;
             return null;

packages/cloudflare/test/instrumentations/worker/instrumentQueue.test.ts

@@ -258,6 +258,7 @@ describe('instrumentQueue', () => {
         env => ({
           dsn: env.SENTRY_DSN,
           tracesSampleRate: 1,
+          traceLifecycle: 'static',
           beforeSendTransaction(event) {
             sentryEvent = event;
             return null;

packages/cloudflare/test/instrumentations/worker/instrumentScheduled.test.ts

@@ -240,6 +240,7 @@ describe('instrumentScheduled', () => {
         env => ({
           dsn: env.SENTRY_DSN,
           tracesSampleRate: 1,
+          traceLifecycle: 'static',
           beforeSendTransaction(event) {
             sentryEvent = event;
             return null;

packages/cloudflare/test/opentelemetry.test.ts

@@ -16,6 +16,7 @@ describe('opentelemetry compatibility', () => {
     const client = init({
       dsn: 'https://username@domain/123',
       tracesSampleRate: 1,
+      traceLifecycle: 'static',
       skipOpenTelemetrySetup: true,
       beforeSendTransaction: event => {
         transactionEvents.push(event);
@@ -46,6 +47,7 @@ describe('opentelemetry compatibility', () => {
     const client = init({
       dsn: 'https://username@domain/123',
       tracesSampleRate: 1,
+      traceLifecycle: 'static',
       beforeSendTransaction: event => {
         transactionEvents.push(event);
         return null;
@@ -106,6 +108,7 @@ describe('opentelemetry compatibility', () => {
     const client = init({
       dsn: 'https://username@domain/123',
       tracesSampleRate: 1,
+      traceLifecycle: 'static',
       beforeSendTransaction: event => {
         transactionEvents.push(event);
         return null;
@@ -149,6 +152,7 @@ describe('opentelemetry compatibility', () => {
     const client = init({
       dsn: 'https://username@domain/123',
       tracesSampleRate: 1,
+      traceLifecycle: 'static',
       beforeSendTransaction: event => {
         transactionEvents.push(event);
         return null;
@@ -176,6 +180,7 @@ describe('opentelemetry compatibility', () => {
     const client = init({
       dsn: 'https://username@domain/123',
       tracesSampleRate: 1,
+      traceLifecycle: 'static',
       beforeSendTransaction: event => {
         transactionEvents.push(event);
         return null;