[BUGFIX] generate editor preview URLs without workspace split compare

Avoid passing the active workspace into preview URI generation for the
visual editor.

This stops the editor from rendering the workspace split compare preview
and keeps page editing in the regular frontend view.

Author: Kanti

.gitattributes

@@ -0,0 +1,21 @@
+# Exclude development and local-only files from git archive / TER zip exports.
+
+.codex export-ignore
+.editorconfig export-ignore
+.gitignore export-ignore
+.github/ export-ignore
+.idea/ export-ignore
+
+grumphp.yml export-ignore
+phpstan-baseline-13.neon export-ignore
+phpstan-baseline-14.neon export-ignore
+phpstan-baseline.neon export-ignore
+phpstan.neon export-ignore
+rector.php export-ignore
+
+public/ export-ignore
+var/ export-ignore
+vendor/ export-ignore
+
+Resources/Public/JavaScript/tsconfig.json export-ignore
+Resources/Public/JavaScript/**/*.test.js export-ignore

.gitignore

@@ -3,4 +3,5 @@
 /vendor/
 /composer.lock
 /public/
-phpstan-baseline.neon
+/phpstan-baseline.neon
+/.codex

Classes/Backend/Controller/PageEditController.php

@@ -24,6 +24,7 @@
 use TYPO3\CMS\Backend\Template\ModuleTemplateFactory;
 use TYPO3\CMS\Backend\Utility\BackendUtility;
 use TYPO3\CMS\Core\Authentication\BackendUserAuthentication;
+use TYPO3\CMS\Core\Context\Context;
 use TYPO3\CMS\Core\Database\Connection;
 use TYPO3\CMS\Core\Database\ConnectionPool;
 use TYPO3\CMS\Core\Database\Query\Restriction\DeletedRestriction;
@@ -95,6 +96,7 @@ public function __construct(
         private readonly Typo3Version $typo3Version,
         private readonly ConnectionPool $connectionPool,
         private readonly AssetCollector $assetCollector,
+        private readonly Context $context,
     ) {
     }
 
@@ -204,7 +206,20 @@ private function iframeUrl(ServerRequestInterface $request, SiteLanguage $siteLa
         ];
         $previewUriBuilder = PreviewUriBuilder::create($this->pageRecord->getRawRecord()->toArray())
             ->withAdditionalQueryParameters($parameters);
-        $uri = $previewUriBuilder->buildUri();
+
+        // unset the context workspace so we do not get the split screen workspace preview in the editor.
+        $context = clone $this->context;
+        $context->unsetAspect('workspace');
+
+        // setting the workspace in $GLOBALS['BE_USER'] is needed until https://review.typo3.org/c/Packages/TYPO3.CMS/+/93603 is merged and than the lowest supported version includes it.
+        $workspace = $this->getBackendUser()->workspace;
+        $this->getBackendUser()->workspace = 0;
+        try {
+            $uri = $previewUriBuilder->buildUri(context: $context);
+        } finally {
+            $this->getBackendUser()->workspace = $workspace;
+        }
+
         if (!$uri instanceof UriInterface) {
             throw new InvalidArgumentException('Could not generate preview URI for page ' . $this->pageRecord->getUid(), 4148517490);
         }