Disable in ReactMarkup

Author: sebmarkbage

packages/react-dom-bindings/src/server/ReactFizzConfigDOM.js

@@ -5033,6 +5033,7 @@ export function writePreambleStart(
   resumableState: ResumableState,
   renderState: RenderState,
   willFlushAllSegments: boolean,
+  skipExpect?: boolean, // Used as an override by ReactFizzConfigMarkup
 ): void {
   // This function must be called exactly once on every request
   if (
@@ -5118,7 +5119,7 @@ export function writePreambleStart(
   renderState.bulkPreloads.forEach(flushResource, destination);
   renderState.bulkPreloads.clear();
 
-  if (htmlChunks || headChunks) {
+  if ((htmlChunks || headChunks) && !skipExpect) {
     // If we have any html or head chunks we know that we're rendering a full document.
     // A full document should block display until the full shell has downloaded.
     // Therefore we insert a render blocking instruction referring to the last body

packages/react-markup/src/ReactFizzConfigMarkup.js

@@ -17,7 +17,10 @@ import type {
   FormatContext,
 } from 'react-dom-bindings/src/server/ReactFizzConfigDOM';
 
-import {pushStartInstance as pushStartInstanceImpl} from 'react-dom-bindings/src/server/ReactFizzConfigDOM';
+import {
+  pushStartInstance as pushStartInstanceImpl,
+  writePreambleStart as writePreambleStartImpl,
+} from 'react-dom-bindings/src/server/ReactFizzConfigDOM';
 
 import type {
   Destination,
@@ -62,13 +65,11 @@ export {
   writeEndPendingSuspenseBoundary,
   writeHoistablesForBoundary,
   writePlaceholder,
-  writeCompletedRoot,
   createRootFormatContext,
   createRenderState,
   createResumableState,
   createPreambleState,
   createHoistableState,
-  writePreambleStart,
   writePreambleEnd,
   writeHoistables,
   writePostamble,
@@ -203,5 +204,30 @@ export function writeEndClientRenderedSuspenseBoundary(
   return true;
 }
 
+export function writePreambleStart(
+  destination: Destination,
+  resumableState: ResumableState,
+  renderState: RenderState,
+  willFlushAllSegments: boolean,
+  skipExpect?: boolean, // Used as an override by ReactFizzConfigMarkup
+): void {
+  return writePreambleStartImpl(
+    destination,
+    resumableState,
+    renderState,
+    willFlushAllSegments,
+    true, // skipExpect
+  );
+}
+
+export function writeCompletedRoot(
+  destination: Destination,
+  resumableState: ResumableState,
+  renderState: RenderState,
+): boolean {
+  // Markup doesn't have any bootstrap scripts nor shell completions.
+  return true;
+}
+
 export type TransitionStatus = FormStatus;
 export const NotPendingTransition: TransitionStatus = NotPending;