fix(v10/server-runtime-injection): Load ESM hook without the build/esm package.json marker

packages/server-utils/src/orchestrion/runtime/register.ts

@@ -105,6 +105,14 @@ export function registerDiagnosticsChannelInjection(_options?: RegisterDiagnosti
       // Our own bundled copy of the tracing-hooks async hooks (see
       // `src/orchestrion/runtime/hook.mjs`) — the dependency itself is bundled into this package's
       // build and no longer resolvable as a bare specifier at runtime.
+      // Deployments can omit the package marker that tells Node these bundled hook files are ESM.
+      const esmDirUrl = new URL('../../../esm/', parentURL).href;
+      mod.register(
+        `data:text/javascript,${encodeURIComponent(
+          `const d=${JSON.stringify(esmDirUrl)};export async function load(u,c,n){return n(u,u.startsWith(d)?{...c,format:'module'}:c)}`,
+        )}`,
+      );
+
       mod.register('@sentry/server-utils/orchestrion/hook', {
         parentURL,
         data: { instrumentations: SENTRY_INSTRUMENTATIONS, diagnosticsPort },

packages/server-utils/test/orchestrion/esmMarker.test.ts

@@ -0,0 +1,45 @@
+import { spawnSync } from 'node:child_process';
+import { cpSync, mkdtempSync, rmSync } from 'node:fs';
+import { join } from 'node:path';
+import { afterAll, describe, expect, it } from 'vitest';
+
+/**
+ * Deployments can drop `build/esm/package.json` (the only `"type": "module"` marker for the hook),
+ * and Vercel runs Node with syntax detection disabled, so the loader thread then parses the hook as
+ * CommonJS. Runs against the built files, so it needs the package built.
+ *
+ * The copy sits inside this package so `@sentry/*` still resolves from its `node_modules`.
+ */
+const copyDir = mkdtempSync(join(__dirname, '.esm-marker-'));
+cpSync(join(__dirname, '../..', 'build'), join(copyDir, 'build'), { recursive: true });
+cpSync(join(__dirname, '../..', 'package.json'), join(copyDir, 'package.json'));
+rmSync(join(copyDir, 'build', 'esm', 'package.json'));
+
+afterAll(() => {
+  rmSync(copyDir, { recursive: true, force: true });
+});
+
+describe('without the build/esm package.json marker', () => {
+  it('registers the ESM loader hook', { timeout: 30_000 }, () => {
+    // Removing `registerHooks` forces the `Module.register()` path, the one that loads the hook on
+    // Node < 24.13, whatever Node version runs the test.
+    const script = `
+      require('node:module').registerHooks = undefined;
+      require('@sentry/core').debug.warn = (...args) => console.error(...args);
+      const { registerDiagnosticsChannelInjection } = require(${JSON.stringify(join(copyDir, 'build', 'cjs', 'orchestrion', 'runtime', 'register.js'))});
+      registerDiagnosticsChannelInjection();
+      import('data:text/javascript,export default 1').then(() => {
+        const marker = globalThis.__SENTRY__?.__SENTRY_ORCHESTRION__ ?? globalThis.__SENTRY_ORCHESTRION__;
+        process.stdout.write(JSON.stringify(marker));
+      });
+    `;
+
+    const { stdout, stderr, status } = spawnSync(process.execPath, ['--no-experimental-detect-module', '-e', script], {
+      encoding: 'utf8',
+    });
+
+    expect(status, stderr).toBe(0);
+    expect(stderr).not.toContain('Failed to register diagnostics-channel injection hooks');
+    expect(JSON.parse(stdout)).toEqual({ runtime: [] });
+  });
+});