diff --git a/changelog.d/fixes/10936-standalone-server-cjs-esm-scope.md b/changelog.d/fixes/10936-standalone-server-cjs-esm-scope.md
new file mode 100644
index 0000000000..824f7df647
--- /dev/null
+++ b/changelog.d/fixes/10936-standalone-server-cjs-esm-scope.md
@@ -0,0 +1 @@
+- **fix(build):** the `next` Docker image no longer crashes on boot with `ReferenceError: require is not defined in ES module scope`. The standalone `server.js` is CommonJS, but the `postbuild` colocate step was re-adding `"type":"module"` to the standalone root `package.json` (undoing `assembleStandalone`'s strip) to make its ESM worker bundles load. The `type:module` scope is now written per-worker-directory instead of on the root, so `server.js` stays CommonJS while the workers stay ESM ([#10936](https://github.com/diegosouzapw/OmniRoute/pull/10936), fixes [#10933](https://github.com/diegosouzapw/OmniRoute/issues/10933)) — thanks @arminanton
diff --git a/scripts/build/colocate-standalone.mjs b/scripts/build/colocate-standalone.mjs
index 0748cf6db7..bb108da47f 100644
--- a/scripts/build/colocate-standalone.mjs
+++ b/scripts/build/colocate-standalone.mjs
@@ -16,14 +16,20 @@
  *
  * Run manually after a build, or automatically via the `postbuild` npm hook.
  */
-import { cpSync, existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
+import { cpSync, existsSync, mkdirSync, writeFileSync } from "node:fs";
 import { dirname, join } from "node:path";
 import { execFileSync } from "node:child_process";
-import { fileURLToPath } from "node:url";
+import { fileURLToPath, pathToFileURL } from "node:url";
 import { computeDependencyClosure } from "./colocateOptionals.mjs";
 
 const ROOT = dirname(dirname(dirname(fileURLToPath(import.meta.url))));
-const STANDALONE = join(ROOT, ".build", "next", "standalone");
+// STANDALONE defaults to the real build output; OMNIROUTE_STANDALONE_DIR overrides
+// it so tests can drive the co-location logic against a synthetic tree without a
+// full `next build`. Mirrors the OMNIROUTE_* override seams in the sibling build
+// scripts (write-build-sha.mjs, write-build-base-path.mjs, optionalPackStaging.mjs).
+const STANDALONE = process.env.OMNIROUTE_STANDALONE_DIR
+  ? process.env.OMNIROUTE_STANDALONE_DIR
+  : join(ROOT, ".build", "next", "standalone");
 
 const CALL_LOG_WORKER_REL = join("src", "lib", "usage", "callLogArtifactWorker.js");
 const CALL_LOG_WORKER_SRC = join(ROOT, "src", "lib", "usage", "callLogArtifactWorker.ts");
@@ -35,97 +41,138 @@ const WORKER_REL = join(
   "llmlingua",
   "onnxWorker.js"
 );
-const GATE_PKG = join("node_modules", "@atjsh", "llmlingua-2", "package.json");
 
-const hasOptionals = existsSync(
-  join(ROOT, "node_modules", "@atjsh", "llmlingua-2", "package.json")
-);
-
-if (!existsSync(STANDALONE)) {
-  console.log("[colocate-standalone] .build/next/standalone not found — nothing to do.");
-  process.exit(0);
-}
-const callLogWorkerDest = join(STANDALONE, CALL_LOG_WORKER_REL);
-mkdirSync(dirname(callLogWorkerDest), { recursive: true });
-execFileSync(
-  join(ROOT, "node_modules", ".bin", "esbuild"),
-  [
-    CALL_LOG_WORKER_SRC,
-    "--bundle",
-    "--platform=node",
-    "--packages=external",
-    "--format=esm",
-    `--outfile=${callLogWorkerDest}`,
-  ],
-  { stdio: "inherit" }
-);
-console.log("[colocate-standalone] ✅ call-log artifact worker bundled");
-
-if (!hasOptionals) {
-  console.log(
-    "[colocate-standalone] optional SLM deps absent at root node_modules — LLMLingua stays fail-open (slim install)."
-  );
-  process.exit(0);
-}
-
-// 1) Bundle the worker the resolver expects: <standalone>/open-sse/.../onnxWorker.js
-const workerDest = join(STANDALONE, WORKER_REL);
-if (!existsSync(workerDest)) {
-  mkdirSync(dirname(workerDest), { recursive: true });
-  try {
-    execFileSync(
-      join(ROOT, "node_modules", ".bin", "esbuild"),
-      [
-        join(ROOT, "open-sse", "services", "compression", "engines", "llmlingua", "onnxWorker.ts"),
-        "--bundle",
-        "--platform=node",
-        "--packages=external",
-        "--format=esm",
-        `--outfile=${workerDest}`,
-      ],
-      { stdio: "inherit" }
-    );
-    console.log("[colocate-standalone] ✅ LLMLingua worker bundled into standalone tree");
-  } catch (err) {
-    console.warn("[colocate-standalone] ⚠️  worker bundle error:", err.message);
-  }
-} else {
-  console.log("[colocate-standalone] worker already present (skipping bundle)");
-}
-
-// 2) Co-locate the optional-dep closure (NO-CLOBBER, same semantics as colocateOptionals.mjs)
-const srcNm = join(ROOT, "node_modules");
-const dstNm = join(STANDALONE, "node_modules");
-const closure = computeDependencyClosure(srcNm);
-let copied = 0;
-for (const pkg of closure) {
-  const src = join(srcNm, pkg);
-  const dst = join(dstNm, pkg);
-  if (!existsSync(src)) continue;
-  if (existsSync(dst)) continue; // no-clobber: keep traced instances (e.g. pinned @huggingface/transformers)
-  mkdirSync(dirname(dst), { recursive: true });
-  cpSync(src, dst, { recursive: true });
-  copied++;
-}
-console.log(
-  `[colocate-standalone] ✅ optional-dep closure: ${closure.length} packages (copied ${copied})`
-);
-
-// 3) Ensure standalone package.json declares "type": "module" so Node 24 runs ESM worker bundles without warning
-const standalonePkgPath = join(STANDALONE, "package.json");
-if (existsSync(standalonePkgPath)) {
-  try {
-    const rawPkg = readFileSync(standalonePkgPath, "utf8");
-    const pkgJson = JSON.parse(rawPkg);
-    if (!pkgJson.type) {
-      pkgJson.type = "module";
-      writeFileSync(standalonePkgPath, JSON.stringify(pkgJson, null, 2) + "\n", "utf8");
-      console.log("[colocate-standalone] ✅ standalone package.json configured with type: module");
+/**
+ * Give each esbuild'd ESM worker its OWN `"type":"module"` scope.
+ *
+ * The worker bundles are emitted with `--format=esm` under `.js` names, so Node
+ * needs a nearest-ancestor package.json declaring `"type":"module"` to load them
+ * as ESM. It is tempting to set that on the standalone ROOT package.json, but the
+ * standalone entrypoint `server.js` is CommonJS (`require()`, `__dirname`); a root
+ * `"type":"module"` makes Node parse server.js as ESM and it crashes at startup
+ * with `ReferenceError: require is not defined in ES module scope`.
+ * assembleStandalone.mjs::patchStandalonePackageJson strips `type` for exactly
+ * this reason — re-adding it on the root here reintroduced that crash.
+ *
+ * Node resolves module type from the NEAREST package.json, so a scoped
+ * `{"type":"module"}` beside each worker makes the worker ESM while the root stays
+ * CommonJS for server.js. Both coexist with no format change and no root edit.
+ *
+ * @param {string[]} workerDirs Absolute directories that hold an ESM worker bundle.
+ * @returns {string[]} The package.json paths that were written (existing ones are left intact).
+ */
+export function writeEsmWorkerScopes(workerDirs) {
+  const written = [];
+  for (const dir of workerDirs) {
+    const scopedPkgPath = join(dir, "package.json");
+    if (existsSync(scopedPkgPath)) continue; // never clobber a traced package.json
+    try {
+      writeFileSync(scopedPkgPath, JSON.stringify({ type: "module" }, null, 2) + "\n", "utf8");
+      written.push(scopedPkgPath);
+      console.log(`[colocate-standalone] ✅ ESM scope written: ${scopedPkgPath}`);
+    } catch (err) {
+      console.warn(`[colocate-standalone] ⚠️  could not write ESM scope for ${dir}:`, err.message);
     }
-  } catch (err) {
-    console.warn(
-      "[colocate-standalone] ⚠️  could not update standalone package.json:",
-      err.message
-    );
   }
+  return written;
+}
+
+function main() {
+  const hasOptionals = existsSync(
+    join(ROOT, "node_modules", "@atjsh", "llmlingua-2", "package.json")
+  );
+
+  if (!existsSync(STANDALONE)) {
+    console.log("[colocate-standalone] .build/next/standalone not found — nothing to do.");
+    return;
+  }
+
+  const callLogWorkerDest = join(STANDALONE, CALL_LOG_WORKER_REL);
+  mkdirSync(dirname(callLogWorkerDest), { recursive: true });
+  execFileSync(
+    join(ROOT, "node_modules", ".bin", "esbuild"),
+    [
+      CALL_LOG_WORKER_SRC,
+      "--bundle",
+      "--platform=node",
+      "--packages=external",
+      "--format=esm",
+      `--outfile=${callLogWorkerDest}`,
+    ],
+    { stdio: "inherit" }
+  );
+  console.log("[colocate-standalone] ✅ call-log artifact worker bundled");
+
+  // The call-log worker is always present; scope it to ESM immediately. The
+  // optional LLMLingua worker dir is added below only when its deps are installed.
+  const workerDirs = [dirname(callLogWorkerDest)];
+
+  if (!hasOptionals) {
+    console.log(
+      "[colocate-standalone] optional SLM deps absent at root node_modules — LLMLingua stays fail-open (slim install)."
+    );
+    writeEsmWorkerScopes(workerDirs);
+    return;
+  }
+
+  // 1) Bundle the worker the resolver expects: <standalone>/open-sse/.../onnxWorker.js
+  const workerDest = join(STANDALONE, WORKER_REL);
+  if (!existsSync(workerDest)) {
+    mkdirSync(dirname(workerDest), { recursive: true });
+    try {
+      execFileSync(
+        join(ROOT, "node_modules", ".bin", "esbuild"),
+        [
+          join(
+            ROOT,
+            "open-sse",
+            "services",
+            "compression",
+            "engines",
+            "llmlingua",
+            "onnxWorker.ts"
+          ),
+          "--bundle",
+          "--platform=node",
+          "--packages=external",
+          "--format=esm",
+          `--outfile=${workerDest}`,
+        ],
+        { stdio: "inherit" }
+      );
+      console.log("[colocate-standalone] ✅ LLMLingua worker bundled into standalone tree");
+    } catch (err) {
+      console.warn("[colocate-standalone] ⚠️  worker bundle error:", err.message);
+    }
+  } else {
+    console.log("[colocate-standalone] worker already present (skipping bundle)");
+  }
+  workerDirs.push(dirname(workerDest));
+
+  // 2) Co-locate the optional-dep closure (NO-CLOBBER, same semantics as colocateOptionals.mjs)
+  const srcNm = join(ROOT, "node_modules");
+  const dstNm = join(STANDALONE, "node_modules");
+  const closure = computeDependencyClosure(srcNm);
+  let copied = 0;
+  for (const pkg of closure) {
+    const src = join(srcNm, pkg);
+    const dst = join(dstNm, pkg);
+    if (!existsSync(src)) continue;
+    if (existsSync(dst)) continue; // no-clobber: keep traced instances (e.g. pinned @huggingface/transformers)
+    mkdirSync(dirname(dst), { recursive: true });
+    cpSync(src, dst, { recursive: true });
+    copied++;
+  }
+  console.log(
+    `[colocate-standalone] ✅ optional-dep closure: ${closure.length} packages (copied ${copied})`
+  );
+
+  // 3) Give each esbuild'd ESM worker its own "type":"module" scope (see helper doc).
+  writeEsmWorkerScopes(workerDirs);
+}
+
+// Run as a script (npm `postbuild` hook), but stay importable for unit tests.
+const entryScript = process.argv[1] ? pathToFileURL(process.argv[1]).href : null;
+if (entryScript === import.meta.url) {
+  main();
 }
diff --git a/tests/unit/build/colocate-standalone-esm-scope.test.ts b/tests/unit/build/colocate-standalone-esm-scope.test.ts
new file mode 100644
index 0000000000..548d72f6f1
--- /dev/null
+++ b/tests/unit/build/colocate-standalone-esm-scope.test.ts
@@ -0,0 +1,129 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { mkdtempSync, mkdirSync, writeFileSync, readFileSync, existsSync, rmSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { execFileSync } from "node:child_process";
+
+import { writeEsmWorkerScopes } from "../../../scripts/build/colocate-standalone.mjs";
+
+/**
+ * Regression coverage for the standalone CJS/ESM `package.json` conflict.
+ *
+ * The Next.js standalone entrypoint `server.js` is CommonJS, so the standalone
+ * root `package.json` must NOT carry `"type":"module"` (assembleStandalone strips
+ * it). The colocated worker bundles are ESM `.js` files that DO need a
+ * `"type":"module"` scope. Setting it on the root satisfied the workers but broke
+ * server.js with `ReferenceError: require is not defined in ES module scope`.
+ *
+ * The fix scopes `"type":"module"` to each worker directory instead of the root.
+ */
+
+test("writeEsmWorkerScopes writes a scoped type:module beside each worker", () => {
+  const root = mkdtempSync(join(tmpdir(), "colocate-scope-"));
+  try {
+    const workerA = join(root, "src", "lib", "usage");
+    const workerB = join(root, "open-sse", "services", "compression", "engines", "llmlingua");
+    mkdirSync(workerA, { recursive: true });
+    mkdirSync(workerB, { recursive: true });
+
+    const written = writeEsmWorkerScopes([workerA, workerB]);
+    assert.equal(written.length, 2, "both worker dirs get a package.json");
+
+    for (const dir of [workerA, workerB]) {
+      const pkg = JSON.parse(readFileSync(join(dir, "package.json"), "utf8"));
+      assert.equal(pkg.type, "module", `${dir} declares type:module`);
+    }
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
+test("writeEsmWorkerScopes never touches the standalone root package.json", () => {
+  const root = mkdtempSync(join(tmpdir(), "colocate-root-"));
+  try {
+    // Standalone root as assembleStandalone leaves it: CommonJS, no `type`.
+    const rootPkgPath = join(root, "package.json");
+    writeFileSync(rootPkgPath, JSON.stringify({ name: "omniroute-standalone" }, null, 2) + "\n");
+
+    const workerDir = join(root, "src", "lib", "usage");
+    mkdirSync(workerDir, { recursive: true });
+    writeEsmWorkerScopes([workerDir]);
+
+    const rootPkg = JSON.parse(readFileSync(rootPkgPath, "utf8"));
+    assert.equal(
+      rootPkg.type,
+      undefined,
+      "root package.json stays type-less so server.js is parsed as CommonJS"
+    );
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
+test("writeEsmWorkerScopes is no-clobber: it leaves an existing package.json intact", () => {
+  const root = mkdtempSync(join(tmpdir(), "colocate-noclobber-"));
+  try {
+    const workerDir = join(root, "src", "lib", "usage");
+    mkdirSync(workerDir, { recursive: true });
+    const traced = { name: "already-traced", type: "module", version: "9.9.9" };
+    writeFileSync(join(workerDir, "package.json"), JSON.stringify(traced, null, 2) + "\n");
+
+    const written = writeEsmWorkerScopes([workerDir]);
+    assert.equal(written.length, 0, "existing package.json is not rewritten");
+
+    const pkg = JSON.parse(readFileSync(join(workerDir, "package.json"), "utf8"));
+    assert.equal(pkg.version, "9.9.9", "the traced manifest is preserved verbatim");
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
+// End-to-end proof that the scoping actually lets a CommonJS server.js and an ESM
+// worker.js coexist under Node's nearest-package.json module resolution. This is
+// the behavior the bug broke: with type:module on the root, `node server.js`
+// threw "require is not defined in ES module scope".
+test("scoped layout runs a CJS server.js and an ESM worker.js side by side", () => {
+  const root = mkdtempSync(join(tmpdir(), "colocate-e2e-"));
+  try {
+    // Root: CommonJS entrypoint, no `type` (what assembleStandalone produces).
+    writeFileSync(join(root, "package.json"), JSON.stringify({ name: "standalone" }) + "\n");
+    writeFileSync(
+      join(root, "server.js"),
+      'const path = require("path");\nprocess.stdout.write("CJS_SERVER_OK:" + path.basename(__filename));\n'
+    );
+
+    // Worker: ESM bundle under its own directory.
+    const workerDir = join(root, "src", "lib", "usage");
+    mkdirSync(workerDir, { recursive: true });
+    writeFileSync(
+      join(workerDir, "callLogArtifactWorker.js"),
+      'import os from "node:os";\nprocess.stdout.write("ESM_WORKER_OK:" + typeof os.cpus);\n'
+    );
+
+    writeEsmWorkerScopes([workerDir]);
+
+    const serverOut = execFileSync(process.execPath, [join(root, "server.js")], {
+      encoding: "utf8",
+    });
+    assert.match(
+      serverOut,
+      /CJS_SERVER_OK:server\.js/,
+      "CommonJS server.js runs under the type-less root"
+    );
+
+    const workerOut = execFileSync(
+      process.execPath,
+      [join(workerDir, "callLogArtifactWorker.js")],
+      { encoding: "utf8" }
+    );
+    assert.match(
+      workerOut,
+      /ESM_WORKER_OK:function/,
+      "ESM worker.js runs under its scoped package.json"
+    );
+    assert.ok(existsSync(join(workerDir, "package.json")), "worker scope package.json exists");
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});