@@ -14,6 +14,7 @@
     "test:build:tunnel-static": "pnpm install && E2E_TEST_TUNNEL_ROUTE_MODE=static E2E_TEST_DSN=http://public@localhost:3031/1337 pnpm build",
     "test:build:tunnel-custom": "pnpm install && E2E_TEST_CUSTOM_TUNNEL_ROUTE=1 pnpm build",
     "test:build:tunnel-object": "pnpm install && E2E_TEST_TUNNEL_ROUTE_MODE=object E2E_TEST_DSN=http://public@localhost:3031/1337 pnpm build",
+    "test:build:hoisted": "pnpm install --config.node-linker=hoisted && pnpm build",
     "test:build-latest": "pnpm add @tanstack/react-start@latest @tanstack/react-router@latest nitro@latest vite@latest @vitejs/plugin-react-swc@latest vite-tsconfig-paths@latest && pnpm install && pnpm build",
     "test:assert:proxy": "pnpm test && TEST_ENV=development pnpm playwright test db-drivers",
     "test:assert": "pnpm test:assert:proxy",
@@ -51,6 +52,10 @@
   },
   "sentryTest": {
     "variants": [
+      {
+        "label": "tanstackstart-react (hoisted)",
+        "build-command": "pnpm test:build:hoisted"
+      },
       {
         "label": "tanstackstart-react (tunnel-generated)",
         "build-command": "pnpm test:build:tunnel-generated",
 
@@ -0,0 +1,22 @@
+import { readdirSync, readFileSync } from 'node:fs';
+import path from 'node:path';
+import { expect, test } from '@playwright/test';
+import { bundleReferencesModule } from '@sentry-internal/test-utils';
+
+// Nitro can't follow the `__require()` calls that Vite 8 emits for external requires in bundled
+// CommonJS, so the deployed server fails with `Cannot find module`. Only flat installs (the hoisted
+// variant) keep the drivers' dependencies external.
+// https://vite.dev/guide/migration#require-calls-for-externalized-modules
+test('bundles the CommonJS dependencies of the instrumented drivers', () => {
+  const root = path.join(process.cwd(), '.output/server');
+  const serverBundle = readdirSync(root, { recursive: true, encoding: 'utf8' })
+    .filter(file => /\.m?js$/.test(file) && !file.startsWith('node_modules'))
+    .map(file => readFileSync(path.join(root, file), 'utf8'))
+    .join('\n');
+  const driverDependencies = ['sqlstring', 'bignumber.js', 'denque', 'cluster-key-slot', 'standard-as-callback'];
+
+  const externalRequires = [...serverBundle.matchAll(/__require\(["']([^"']+)["']\)/g)].map(match => match[1]);
+
+  expect(bundleReferencesModule(serverBundle, 'mysql'), 'mysql must be bundled to be instrumented').toBe(false);
+  expect(externalRequires.filter(name => driverDependencies.includes(name))).toEqual([]);
+});
@@ -0,0 +1,125 @@
+import { isPlainObject } from '@sentry/core';
+import { readFileSync } from 'node:fs';
+import { createRequire, isBuiltin } from 'node:module';
+import { isAbsolute } from 'node:path';
+import type { Plugin } from 'vite';
+
+type ResolveIdHandler = Extract<NonNullable<Plugin['resolveId']>, (...args: never[]) => unknown>;
+type ResolveIdParameters = Parameters<ResolveIdHandler>;
+
+const NODE_MODULES = '/node_modules/';
+
+/**
+ * Creates a `resolveId` handler that bundles the external packages that bundled CommonJS `require()`s.
+ *
+ * Rolldown keeps these calls as `__require()`, which a second bundler over the server output can't follow:
+ * - https://vite.dev/guide/migration#require-calls-for-externalized-modules
+ * - https://rolldown.rs/in-depth/bundling-cjs#require-external-modules
+ *
+ * Only handles requires from packages bundled for orchestrion, and from packages bundled because of them.
+ */
+export function createExternalRequireResolver(
+  moduleNames: readonly string[],
+): (this: ThisParameterType<ResolveIdHandler>, ...args: ResolveIdParameters) => Promise<string | null> {
+  const bundledPackagesByEnvironment = new Map<string, Set<string>>();
+
+  return async function resolveExternalRequire(source, importer, options) {
+    if (
+      !this.meta.rolldownVersion ||
+      this.environment.mode !== 'build' ||
+      options.kind !== 'require-call' ||
+      !importer ||
+      !isPackageSpecifier(source)
+    ) {
+      return null;
+    }
+
+    const bundledPackages = bundledPackagesByEnvironment.get(this.environment.name) ?? new Set(moduleNames);
+    bundledPackagesByEnvironment.set(this.environment.name, bundledPackages);
+
+    const owner = ownerPackage(importer);
+    const name = packageName(source);
+    if (
+      !owner ||
+      !bundledPackages.has(owner.name) ||
+      isUserExternal(this.environment.config.resolve.external, source, name) ||
+      isOptionalDependency(owner.dir, name)
+    ) {
+      return null;
+    }
+
+    const resolved = await this.resolve(source, importer, { ...options, skipSelf: true });
+    if (!resolved) {
+      return null;
+    }
+    // Vite bundles it anyway (e.g. under pnpm), so its own requires count too.
+    if (!resolved.external) {
+      bundledPackages.add(name);
+      return null;
+    }
+
+    const file = resolveWithNode(source, importer);
+    if (file) {
+      bundledPackages.add(name);
+    }
+    return file ?? null;
+  };
+}
+
+function isPackageSpecifier(source: string): boolean {
+  return !isBuiltin(source) && !isAbsolute(source) && !/^[.\0]/.test(source);
+}
+
+// `pg-types/lib/x` → `pg-types`, `@scope/pkg/x` → `@scope/pkg`.
+function packageName(specifier: string): string {
+  const [first = '', second] = specifier.split('/');
+  return first.startsWith('@') && second ? `${first}/${second}` : first;
+}
+
+// Uses the last `node_modules` segment, so nested and pnpm store paths work.
+function ownerPackage(file: string): { name: string; dir: string } | undefined {
+  const path = file.replace(/\\/g, '/');
+  const start = path.lastIndexOf(NODE_MODULES);
+  if (start === -1) {
+    return undefined;
+  }
+  const name = packageName(path.slice(start + NODE_MODULES.length));
+  return { name, dir: `${path.slice(0, start)}${NODE_MODULES}${name}` };
+}
+
+// Matches like Vite. `external: true` is Vite's SSR default, not a choice for this package.
+function isUserExternal(external: readonly string[] | true, source: string, name: string): boolean {
+  return Array.isArray(external) && external.some(entry => entry === source || entry === name);
+}
+
+// These can be missing or native, like `pg-native`.
+function isOptionalDependency(packageDir: string, name: string): boolean {
+  const manifest = readManifest(`${packageDir}/package.json`);
+  if (!manifest) {
+    return false;
+  }
+  const { peerDependenciesMeta, optionalDependencies } = manifest;
+  const peerMeta = isPlainObject(peerDependenciesMeta) ? peerDependenciesMeta[name] : undefined;
+  return (
+    (isPlainObject(peerMeta) && peerMeta.optional === true) ||
+    (isPlainObject(optionalDependencies) && name in optionalDependencies)
+  );
+}
+
+// The file that `require()` loads at runtime.
+function resolveWithNode(source: string, importer: string): string | undefined {
+  try {
+    return createRequire(importer).resolve(source);
+  } catch {
+    return undefined;
+  }
+}
+
+function readManifest(file: string): Record<string, unknown> | undefined {
+  try {
+    const manifest: unknown = JSON.parse(readFileSync(file, 'utf8'));
+    return isPlainObject(manifest) ? manifest : undefined;
+  } catch {
+    return undefined;
+  }
+}
@@ -5,6 +5,7 @@ export type { Plugin as VitePlugin } from 'vite';
 import { instrumentedModuleNames } from '../config';
 import type { PluginOptions } from './options';
 import { externalEntryMatchesModule, externalizedModulesWarning, orchestrionTransformOptions } from './options';
+import { createExternalRequireResolver } from './externalRequire';
 import { resolveOrchestrionRuntimeRequest, SNIPPET_IMPORT_SPECIFIER } from './resolve';
 
 type TransformHandler = (this: unknown, code: string, id: string, opts?: { ssr?: boolean }) => unknown;
@@ -73,6 +74,7 @@ export function sentryOrchestrionPlugin(options: PluginOptions = {}): Plugin {
     ...instrumentedModuleNames(options.instrumentations),
     '@sentry/server-utils',
   ];
+  const resolveExternalRequire = createExternalRequireResolver(noExternalModules());
 
   const instance = {};
   // `true` when an earlier instance of this plugin is in the same build, which then transforms the modules alone.
@@ -94,7 +96,10 @@ export function sentryOrchestrionPlugin(options: PluginOptions = {}): Plugin {
     // packages into default imports, and `@sentry/core` has no default export, so the server
     // crashes at startup. Vite 8 keeps the `require()`s, which loads a second copy of `@sentry/core`.
     async resolveId(source, importer, resolveOptions) {
-      if (source !== SNIPPET_IMPORT_SPECIFIER || !resolveOptions?.ssr) {
+      if (source !== SNIPPET_IMPORT_SPECIFIER) {
+        return resolveExternalRequire.call(this, source, importer, resolveOptions);
+      }
+      if (!resolveOptions?.ssr) {
         return null;
       }
       const resolved = await this.resolve(source, importer, { ...resolveOptions, skipSelf: true });
 
@@ -446,6 +446,27 @@ describe('sentryOrchestrionPlugin (vite)', () => {
     expect(fallback).toMatch(/[/\\]build[/\\]esm[/\\]index\.js$/);
     expect(existsSync(fallback as string)).toBe(true);
   });
+
+  it('resolves the snippet require() to the ESM entry before it handles other requires on Rolldown', async () => {
+    const resolveId = vitePlugin().resolveId as (
+      this: unknown,
+      source: string,
+      importer: string,
+      opts: { ssr: boolean; kind: string },
+    ) => Promise<unknown>;
+    const context = {
+      meta: { rolldownVersion: '1.2.14' },
+      environment: { name: 'ssr', mode: 'build', config: { resolve: { external: [] } } },
+      resolve: vi.fn().mockResolvedValue({ id: '/app/node_modules/@sentry/server-utils/build/cjs/index.js' }),
+    };
+
+    const resolved = await resolveId.call(context, '@sentry/server-utils', '/app/node_modules/pg/lib/client.js', {
+      ssr: true,
+      kind: 'require-call',
+    });
+
+    expect(resolved).toEqual({ id: '/app/node_modules/@sentry/server-utils/build/esm/index.js' });
+  });
 });
 
 describe('sentryOrchestrionPlugin (bun)', () => {
 
@@ -0,0 +1,173 @@
+import { mkdirSync, mkdtempSync, realpathSync, rmSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { createExternalRequireResolver } from '../../src/orchestrion/bundler/externalRequire';
+
+interface ContextOptions {
+  environment?: string;
+  meta?: Record<string, string>;
+  mode?: string;
+  external?: string[] | true;
+  resolved?: { id: string; external?: boolean } | null;
+}
+
+describe('createExternalRequireResolver', () => {
+  let root: string;
+  let pgFile: string;
+
+  function installPackage(name: string, manifest: Record<string, unknown> = {}, parentDir = root): string {
+    const dir = join(parentDir, 'node_modules', name);
+    mkdirSync(dir, { recursive: true });
+    writeFileSync(join(dir, 'package.json'), JSON.stringify({ name, main: 'index.js', ...manifest }));
+    writeFileSync(join(dir, 'index.js'), '');
+    return join(dir, 'index.js');
+  }
+
+  // By default, a Rolldown build in which Vite keeps the required package external.
+  function context({
+    environment = 'ssr',
+    meta = { rolldownVersion: '1.2.14' },
+    mode = 'build',
+    external = [],
+    resolved = { id: 'external', external: true },
+  }: ContextOptions = {}): never {
+    return {
+      meta,
+      environment: { name: environment, mode, config: { resolve: { external } } },
+      resolve: vi.fn().mockResolvedValue(resolved),
+    } as never;
+  }
+
+  function resolveRequire(
+    resolver: ReturnType<typeof createExternalRequireResolver>,
+    source: string,
+    importer: string,
+    contextOptions?: ContextOptions,
+    kind = 'require-call',
+  ): Promise<string | null> {
+    return resolver.call(context(contextOptions), source, importer, { kind, isEntry: false } as never);
+  }
+
+  beforeEach(() => {
+    root = realpathSync(mkdtempSync(join(tmpdir(), 'orch-external-require-')));
+    pgFile = join(root, 'node_modules/pg/lib/client.js');
+    installPackage('pg');
+  });
+
+  afterEach(() => {
+    rmSync(root, { recursive: true, force: true });
+  });
+
+  it('bundles an external package that an instrumented package requires', async () => {
+    const pgTypes = installPackage('pg-types');
+
+    await expect(resolveRequire(createExternalRequireResolver(['pg']), 'pg-types', pgFile)).resolves.toBe(pgTypes);
+  });
+
+  it.each([
+    ['it bundled', { id: 'external', external: true }],
+    ['Vite bundles itself', { id: 'pg-types/index.js' }],
+  ])('follows the requires of a package that %s', async (_, resolved) => {
+    const pgTypes = installPackage('pg-types');
+    const postgresArray = installPackage('postgres-array');
+    const resolver = createExternalRequireResolver(['pg']);
+
+    await resolveRequire(resolver, 'pg-types', pgFile, { resolved });
+
+    await expect(resolveRequire(resolver, 'postgres-array', pgTypes)).resolves.toBe(postgresArray);
+  });
+
+  // Every require() here resolves to a real file, so only the filter can return `null`.
+  it.each([
+    ['app code', 'pg-types', 'src/db.js'],
+    ['a package that orchestrion does not bundle', 'pg-types', 'node_modules/other/index.js'],
+    ['a builtin', 'node:net', 'node_modules/pg/lib/client.js'],
+    ['a relative path', './connection', 'node_modules/pg/lib/client.js'],
+  ])('ignores a require() of %s', async (_, source, importer) => {
+    installPackage('pg-types');
+    installPackage('other');
+    mkdirSync(join(root, 'node_modules/pg/lib'), { recursive: true });
+    writeFileSync(join(root, 'node_modules/pg/lib/connection.js'), '');
+
+    await expect(
+      resolveRequire(createExternalRequireResolver(['pg']), source, join(root, importer)),
+    ).resolves.toBeNull();
+  });
+
+  it('bundles a require() from a pnpm store path', async () => {
+    const store = join(root, 'node_modules/.pnpm/pg@8.23.1');
+    installPackage('pg', {}, store);
+    const pgTypes = installPackage('pg-types', {}, store);
+
+    await expect(
+      resolveRequire(createExternalRequireResolver(['pg']), 'pg-types', join(store, 'node_modules/pg/lib/client.js')),
+    ).resolves.toBe(pgTypes);
+  });
+
+  it('tracks bundled packages for each environment separately', async () => {
+    const pgTypes = installPackage('pg-types');
+    installPackage('postgres-array');
+    const resolver = createExternalRequireResolver(['pg']);
+
+    await resolveRequire(resolver, 'pg-types', pgFile, { environment: 'ssr' });
+
+    await expect(resolveRequire(resolver, 'postgres-array', pgTypes, { environment: 'nitro' })).resolves.toBeNull();
+  });
+
+  it.each([
+    ['on Rollup', { meta: { rollupVersion: '4.0.0' } }, 'require-call'],
+    ['on the dev server', { mode: 'dev' }, 'require-call'],
+    ['for an import', {}, 'import-statement'],
+  ])('leaves resolution to the bundler %s', async (_, contextOptions, kind) => {
+    installPackage('pg-types');
+
+    await expect(
+      resolveRequire(createExternalRequireResolver(['pg']), 'pg-types', pgFile, contextOptions, kind),
+    ).resolves.toBeNull();
+  });
+
+  it.each([
+    ['an optional peer', { peerDependenciesMeta: { 'pg-native': { optional: true } } }],
+    ['an optional dependency', { optionalDependencies: { 'pg-native': '^3' } }],
+  ])('keeps %s external', async (_, manifest) => {
+    installPackage('pg', manifest);
+    installPackage('pg-native');
+
+    await expect(resolveRequire(createExternalRequireResolver(['pg']), 'pg-native', pgFile)).resolves.toBeNull();
+  });
+
+  it('keeps a scoped subpath external when the user lists its package', async () => {
+    installPackage('@scope/pkg');
+    writeFileSync(join(root, 'node_modules/@scope/pkg/sub.js'), '');
+
+    await expect(
+      resolveRequire(createExternalRequireResolver(['pg']), '@scope/pkg/sub', pgFile, { external: ['@scope/pkg'] }),
+    ).resolves.toBeNull();
+  });
+
+  it('keeps a package external that the user lists in `external`', async () => {
+    installPackage('pg-types');
+
+    await expect(
+      resolveRequire(createExternalRequireResolver(['pg']), 'pg-types', pgFile, { external: ['pg-types'] }),
+    ).resolves.toBeNull();
+  });
+
+  it.each([
+    ['only a subpath of the package', ['pg-types/lib/arrays']],
+    ['`true`, the SSR default', true],
+  ] as const)('bundles a package despite an external entry that names %s', async (_, external) => {
+    const pgTypes = installPackage('pg-types');
+
+    await expect(
+      resolveRequire(createExternalRequireResolver(['pg']), 'pg-types', pgFile, {
+        external: external === true ? true : [...external],
+      }),
+    ).resolves.toBe(pgTypes);
+  });
+
+  it('keeps a package external that is not installed', async () => {
+    await expect(resolveRequire(createExternalRequireResolver(['pg']), 'pg-types', pgFile)).resolves.toBeNull();
+  });
+});