fix(sveltekit): Upload source maps with SvelteKit 3 (#25139)

SvelteKit 3 builds all environments in a single Vite build and runs the
adapter in a post `buildApp` hook. Our upload waited for a separate SSR
build in `closeBundle`, which Kit 3 never does, so nothing was uploaded.
We now also upload from a post `buildApp` hook, but only once an
environment has been built. Kit 2 builds only after all `buildApp` hooks
have run, so its `closeBundle` path still does the upload.

Source maps were also never deleted after upload, on Kit 2 or Kit 3. The
deletion check read `build.sourcemap` after our own plugin had already
set it.

The new `sveltekit-3-sourcemaps` e2e app builds against a mock Sentry
server. It asserts that the upload happens, that every debug ID has a
map, and that no maps are left in `build/`.

Fixes #25096

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: chargome

dev-packages/e2e-tests/test-applications/sveltekit-3-sourcemaps/.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+node_modules
+/build
+/.svelte-kit
+
+# Mock Sentry server artifacts
+.tmp_*
+/tmp_mock_chunks

dev-packages/e2e-tests/test-applications/sveltekit-3-sourcemaps/assert-build.ts

@@ -0,0 +1,100 @@
+import * as assert from 'node:assert/strict';
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+import {
+  findInjectedDebugIds,
+  findSourceMapFiles,
+  findSourceMappingUrlComments,
+  getArtifactBundles,
+  getAssembleRequests,
+  getChunkUploadPosts,
+  getDebugIdPairs,
+  getSourcemaps,
+  loadMockServerResults,
+} from '@sentry-internal/test-utils';
+
+const BUILD_OUTPUT = 'build';
+const CLIENT_OUTPUT = path.join(BUILD_OUTPUT, 'client');
+const SERVER_OUTPUT = path.join(BUILD_OUTPUT, 'server');
+
+/** Both markers sit in comments, so bundlers strip them from the code but keep them in `sourcesContent`. */
+const CLIENT_MARKER = 'SOURCEMAP_MARKER_CLIENT';
+const SERVER_MARKER = 'SOURCEMAP_MARKER_SERVER';
+
+/** Written by the build, see `recordChunksWithoutSourceMap` in `vite.config.js`. */
+const debugIdsWithoutSourceMap = new Set(
+  fs.existsSync('.tmp_debug_ids_without_source_map')
+    ? fs.readFileSync('.tmp_debug_ids_without_source_map', 'utf8').split('\n').filter(Boolean)
+    : [],
+);
+
+const requests = loadMockServerResults();
+
+console.log(`Captured ${requests.length} requests to mock Sentry server:\n`);
+for (const request of requests) {
+  console.log(`  ${request.method} ${request.url} (${request.bodySize} bytes)`);
+}
+console.log('');
+
+assert.ok(
+  requests.some(r => r.authorization.includes('fake-auth-token')),
+  'Expected requests with the configured auth token',
+);
+
+assert.ok(
+  requests.some(r => r.url?.includes('/releases') && r.method === 'POST'),
+  'Expected a POST to create the release',
+);
+
+assert.ok(
+  getChunkUploadPosts(requests).some(r => r.bodySize > 0),
+  'Expected at least one chunk upload POST with a non-empty body',
+);
+
+const assembleRequests = getAssembleRequests(requests);
+assert.ok(assembleRequests.length > 0, 'Expected at least one assemble request');
+for (const request of assembleRequests) {
+  assert.ok(request.assembleBody?.projects?.includes('test-project'), 'Expected assemble request for test-project');
+  assert.equal(request.assembleBody?.version, 'test-release', 'Expected assemble request to reference the release');
+}
+
+const bundles = getArtifactBundles(requests);
+assert.ok(bundles.length > 0, 'Expected at least one artifact bundle with a manifest');
+
+const sourcemaps = getSourcemaps(bundles);
+
+const containsMarker = (marker: string): boolean =>
+  sourcemaps.some(map => map.sourcemap.sourcesContent?.some(source => source?.includes(marker)));
+
+assert.ok(containsMarker(CLIENT_MARKER), 'Expected an uploaded sourcemap carrying the client source');
+assert.ok(containsMarker(SERVER_MARKER), 'Expected an uploaded sourcemap carrying the server source');
+
+// The auto-instrument plugin loads wrapped modules under this suffix. It must be stripped before
+// upload, or the uploaded sources don't match the frames Sentry receives.
+const wrappedSources = sourcemaps
+  .flatMap(map => map.sourcemap.sources ?? [])
+  .filter(source => source.includes('?sentry-auto-wrap'));
+assert.deepEqual(wrappedSources, [], 'Expected no uploaded source to carry the auto-wrap query suffix');
+
+const uploadedDebugIds = new Set(getDebugIdPairs(bundles).map(pair => pair.debugId.toLowerCase()));
+assert.ok(uploadedDebugIds.size > 0, 'Expected at least one JS/sourcemap pair with matching debug IDs');
+
+for (const outputDir of [CLIENT_OUTPUT, SERVER_OUTPUT]) {
+  const injectedDebugIds = findInjectedDebugIds({ outputDir });
+  assert.ok(injectedDebugIds.length > 0, `Expected debug IDs to be injected into ${outputDir}`);
+
+  const unuploaded = injectedDebugIds.filter(
+    debugId => !uploadedDebugIds.has(debugId) && !debugIdsWithoutSourceMap.has(debugId),
+  );
+  assert.deepEqual(unuploaded, [], `Expected every debug ID in ${outputDir} to have an uploaded sourcemap`);
+}
+
+// The app does not set `build.sourcemap`, so the SDK enables hidden maps and must delete them after upload.
+assert.deepEqual(findSourceMapFiles({ outputDir: BUILD_OUTPUT }), [], `Expected no source maps in ${BUILD_OUTPUT}`);
+assert.deepEqual(
+  findSourceMappingUrlComments({ outputDir: CLIENT_OUTPUT }),
+  [],
+  `Expected no sourceMappingURL comments in ${CLIENT_OUTPUT}`,
+);
+
+console.log('All sourcemap assertions passed!');

dev-packages/e2e-tests/test-applications/sveltekit-3-sourcemaps/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "sveltekit-3-sourcemaps",
+  "description": "E2E test app asserting what the SvelteKit SDK uploads to Sentry and what it leaves behind in `build`.",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "build": "node start-mock-sentry-server.mjs & vite build > .tmp_build_stdout 2> .tmp_build_stderr; BUILD_EXIT=$?; kill %1 2>/dev/null; if [ $BUILD_EXIT -ne 0 ]; then cat .tmp_build_stdout; cat .tmp_build_stderr >&2; fi; exit $BUILD_EXIT",
+    "clean": "npx rimraf node_modules pnpm-lock.yaml",
+    "test:build": "pnpm install && pnpm build",
+    "test:assert": "node assert-build.ts"
+  },
+  "dependencies": {
+    "@sentry/sveltekit": "file:../../packed/sentry-sveltekit-packed.tgz"
+  },
+  "devDependencies": {
+    "@sentry-internal/test-utils": "link:../../../test-utils",
+    "@sveltejs/adapter-node": "^6.0.0",
+    "@sveltejs/kit": "^3.0.0",
+    "@sveltejs/vite-plugin-svelte": "^7.3.1",
+    "@types/node": "^22.20.0",
+    "svelte": "^5.57.1",
+    "typescript": "^6.0.0",
+    "vite": "^8.0.12"
+  },
+  "volta": {
+    "node": "22.20.0",
+    "extends": "../../package.json"
+  }
+}

dev-packages/e2e-tests/test-applications/sveltekit-3-sourcemaps/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-sourcemaps/src/app.html

@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <link rel="icon" href="%sveltekit.assets%/favicon.png" />
+    <meta name="viewport" content="width=device-width" />
+    %sveltekit.head%
+  </head>
+  <body data-sveltekit-preload-data="off">
+    <div style="display: contents">%sveltekit.body%</div>
+  </body>
+</html>

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

@@ -0,0 +1,7 @@
+import * as Sentry from '@sentry/sveltekit';
+
+Sentry.init({
+  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+});
+
+export const handleError = Sentry.handleErrorWithSentry();

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

@@ -0,0 +1,5 @@
+import * as Sentry from '@sentry/sveltekit';
+
+export const handleError = Sentry.handleErrorWithSentry();
+
+export const handle = Sentry.sentryHandle();

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

@@ -0,0 +1,6 @@
+import * as Sentry from '@sentry/sveltekit';
+
+// SvelteKit 3 loads this file before the app, which is where `Sentry.init` belongs.
+Sentry.init({
+  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+});

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

@@ -0,0 +1,8 @@
+<script lang="ts">
+  // SOURCEMAP_MARKER_CLIENT
+  function throwError() {
+    throw new Error('Client error');
+  }
+</script>
+
+<button on:click={throwError}>Throw error</button>

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

@@ -0,0 +1,4 @@
+// SOURCEMAP_MARKER_SERVER
+export const load = async () => {
+  throw new Error('Server load error');
+};