test(sveltekit): Enable native OTel tracing in SvelteKit 3 e2e app

Turn on SvelteKit 3's native server-side tracing (`experimental.tracing.server`
and `experimental.instrumentation.server`) so the e2e app exercises the path
where @sentry/sveltekit picks up Kit's OpenTelemetry spans instead of starting
its own `http.server` span.

`Sentry.init` moves to `src/instrumentation.server.ts` (the native instrumentation
entry point); `hooks.server.ts` is reduced to `sequence(sentryHandle())` plus the
error handler. Swap the default-path performance/sdk tests for the native-tracing
`tracing.*` suites and add a `form-action` route to cover form-action spans,
mirroring `sveltekit-2-kit-tracing`. Config is passed via the `sveltekit()` Vite
plugin since SvelteKit 3 dropped `svelte.config.js`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: chargome

dev-packages/e2e-tests/test-applications/sveltekit-3/README.md

@@ -5,6 +5,12 @@ float the `next` dist-tag: `@sveltejs/kit@next`, `@sveltejs/adapter-node@next`,
 `@sveltejs/adapter-auto@next`). Built on Svelte 5, Vite 8, vite-plugin-svelte 7, TypeScript 6,
 Node 22 — the minimums SvelteKit 3 requires.
 
+This app enables SvelteKit's **native server-side OpenTelemetry tracing**
+(`experimental.tracing.server` + `experimental.instrumentation.server`), so the Sentry SDK
+picks up Kit's spans instead of starting its own `http.server` span. `Sentry.init` therefore
+lives in `src/instrumentation.server.ts`, and the `tests/tracing.*` suites assert the native span
+tree (`sveltekit.handle.root`, `function.sveltekit.resolve`, form-action spans, etc.).
+
 ## Status: `sentryTest.skip = true` (draft)
 
 This app is **skipped in CI** because it cannot build on the current SvelteKit 3 prerelease yet.
@@ -13,7 +19,7 @@ The build fails in SvelteKit's own pipeline (reproduced with the Sentry plugin r
 **not** a Sentry issue):
 
 ```
-[vite]: Rolldown failed to resolve import "$env/static/private" from "src/hooks.server.ts"
+[vite]: Rolldown failed to resolve import "$env/static/private" from "src/instrumentation.server.ts"
 ```
 
 SvelteKit 3 ships on Vite 8 / Rolldown, and `$env/*` virtual-module resolution is broken in the

dev-packages/e2e-tests/test-applications/sveltekit-3/src/app.d.ts

@@ -0,0 +1,13 @@
+// See https://kit.svelte.dev/docs/types#app
+// for information about these interfaces
+declare global {
+  namespace App {
+    // interface Error {}
+    // interface Locals {}
+    // interface PageData {}
+    // interface PageState {}
+    // interface Platform {}
+  }
+}
+
+export {};

dev-packages/e2e-tests/test-applications/sveltekit-3/src/hooks.server.ts

@@ -1,15 +1,7 @@
-import { E2E_TEST_DSN } from '$env/static/private';
 import * as Sentry from '@sentry/sveltekit';
-
-Sentry.init({
-  environment: 'qa', // dynamic sampling bias to keep transactions
-  dsn: E2E_TEST_DSN,
-  debug: !!process.env.DEBUG,
-  tunnel: `http://localhost:3031/`, // proxy server
-  tracesSampleRate: 1.0,
-});
+import { sequence } from '@sveltejs/kit/hooks';
 
 // not logging anything to console to avoid noise in the test output
 export const handleError = Sentry.handleErrorWithSentry(() => {});
 
-export const handle = Sentry.sentryHandle();
+export const handle = sequence(Sentry.sentryHandle());

dev-packages/e2e-tests/test-applications/sveltekit-3/src/instrumentation.server.ts

@@ -0,0 +1,12 @@
+import { E2E_TEST_DSN } from '$env/static/private';
+import * as Sentry from '@sentry/sveltekit';
+
+// With SvelteKit 3 native instrumentation enabled (`experimental.instrumentation.server`),
+// `Sentry.init` runs here instead of in `hooks.server.ts`.
+Sentry.init({
+  environment: 'qa', // dynamic sampling bias to keep transactions
+  dsn: E2E_TEST_DSN,
+  debug: !!process.env.DEBUG,
+  tunnel: `http://localhost:3031/`, // proxy server
+  tracesSampleRate: 1.0,
+});

dev-packages/e2e-tests/test-applications/sveltekit-3/src/routes/form-action/+page.server.ts

@@ -0,0 +1,7 @@
+export const actions = {
+  default: async ({ request }) => {
+    const formData = await request.formData();
+    const name = formData.get('name');
+    return { name };
+  },
+};

dev-packages/e2e-tests/test-applications/sveltekit-3/src/routes/form-action/+page.svelte

@@ -0,0 +1,15 @@
+<script>
+  import { enhance } from '$app/forms';
+
+  const { data, form } = $props();
+</script>
+
+<form method="post" use:enhance>
+  <label for="name">Name:</label>
+  <input id="inputName" type="text" name="name" />
+  <button id="buttonSubmit" type="submit">Submit</button>
+</form>
+
+{#if form?.name}
+  <p>Hello {form.name}</p>
+{/if}

dev-packages/e2e-tests/test-applications/sveltekit-3/tests/errors.client.test.ts

@@ -6,7 +6,7 @@ test.describe('client-side errors', () => {
   test('captures error thrown on click', async ({ page }) => {
     await waitForInitialPageload(page, { route: '/client-error' });
 
-    const errorEventPromise = waitForError('sveltekit-2', errorEvent => {
+    const errorEventPromise = waitForError('sveltekit-3', errorEvent => {
       return errorEvent?.exception?.values?.[0]?.value === 'Click Error';
     });
 
@@ -33,7 +33,7 @@ test.describe('client-side errors', () => {
     await waitForInitialPageload(page);
     await page.reload();
 
-    const errorEventPromise = waitForError('sveltekit-2', errorEvent => {
+    const errorEventPromise = waitForError('sveltekit-3', errorEvent => {
       return errorEvent?.exception?.values?.[0]?.value === 'Universal Load Error (browser)';
     });
 

dev-packages/e2e-tests/test-applications/sveltekit-3/tests/errors.server.test.ts

@@ -3,7 +3,7 @@ import { waitForError } from '@sentry-internal/test-utils';
 
 test.describe('server-side errors', () => {
   test('captures universal load error', async ({ page }) => {
-    const errorEventPromise = waitForError('sveltekit-2', errorEvent => {
+    const errorEventPromise = waitForError('sveltekit-3', errorEvent => {
       return errorEvent?.exception?.values?.[0]?.value === 'Universal Load Error (server)';
     });
 
@@ -14,14 +14,25 @@ test.describe('server-side errors', () => {
 
     expect(errorEventFrames?.[errorEventFrames?.length - 1]).toEqual(
       expect.objectContaining({
-        function: 'load$1',
+        function: 'load',
         in_app: true,
       }),
     );
+
+    expect(errorEvent.request).toEqual({
+      cookies: {},
+      headers: expect.objectContaining({
+        accept: expect.any(String),
+        'user-agent': expect.any(String),
+      }),
+      method: 'GET',
+      // SvelteKit's node adapter defaults to https in the protocol even if served on http
+      url: 'http://localhost:3030/universal-load-error',
+    });
   });
 
   test('captures server load error', async ({ page }) => {
-    const errorEventPromise = waitForError('sveltekit-2', errorEvent => {
+    const errorEventPromise = waitForError('sveltekit-3', errorEvent => {
       return errorEvent?.exception?.values?.[0]?.value === 'Server Load Error';
     });
 
@@ -32,14 +43,24 @@ test.describe('server-side errors', () => {
 
     expect(errorEventFrames?.[errorEventFrames?.length - 1]).toEqual(
       expect.objectContaining({
-        function: 'load$1',
+        function: 'load',
         in_app: true,
       }),
     );
+
+    expect(errorEvent.request).toEqual({
+      cookies: {},
+      headers: expect.objectContaining({
+        accept: expect.any(String),
+        'user-agent': expect.any(String),
+      }),
+      method: 'GET',
+      url: 'http://localhost:3030/server-load-error',
+    });
   });
 
   test('captures server route (GET) error', async ({ page }) => {
-    const errorEventPromise = waitForError('sveltekit-2', errorEvent => {
+    const errorEventPromise = waitForError('sveltekit-3', errorEvent => {
       return errorEvent?.exception?.values?.[0]?.value === 'Server Route Error';
     });
 
@@ -50,43 +71,21 @@ test.describe('server-side errors', () => {
 
     expect(errorEventFrames?.[errorEventFrames?.length - 1]).toEqual(
       expect.objectContaining({
-        filename: expect.stringContaining('app:///_server.ts'),
+        filename: expect.stringMatching(/app:\/\/\/_server.ts-.+.js/),
         function: 'GET',
         in_app: true,
       }),
     );
 
     expect(errorEvent.transaction).toEqual('GET /server-route-error');
-  });
 
-  test('captures error() thrown in server route with `wrapServerRouteWithSentry`', async ({ page }) => {
-    const errorEventPromise = waitForError('sveltekit-2', errorEvent => {
-      return errorEvent?.exception?.values?.[0]?.value === "'HttpError' captured as exception with keys: body, status";
-    });
-
-    await page.goto('/wrap-server-route');
-
-    expect(await errorEventPromise).toMatchObject({
-      exception: {
-        values: [
-          {
-            value: "'HttpError' captured as exception with keys: body, status",
-            mechanism: {
-              handled: false,
-              type: 'auto.function.sveltekit.server_route',
-            },
-            stacktrace: { frames: expect.any(Array) },
-          },
-        ],
-      },
-      extra: {
-        __serialized__: {
-          body: {
-            message: 'error() error',
-          },
-          status: 500,
-        },
-      },
+    expect(errorEvent.request).toEqual({
+      cookies: {},
+      headers: expect.objectContaining({
+        accept: expect.any(String),
+      }),
+      method: 'GET',
+      url: 'http://localhost:3030/server-route-error',
     });
   });
 });