diff --git a/extension.json b/extension.json
index c1246e57c..b4f0039df 100644
--- a/extension.json
+++ b/extension.json
@@ -363,6 +363,8 @@
 				"VisualEditor.ParsoidClientFactory",
 				"DiscussionTools.CommentParser",
 				"DiscussionTools.SubscriptionStore",
+				"TempUserCreator",
+				"UserFactory",
 				"SkinFactory",
 				"ConfigFactory",
 				"RevisionLookup"
@@ -395,6 +397,8 @@
 			"services": [
 				"VisualEditor.ParsoidClientFactory",
 				"DiscussionTools.CommentParser",
+				"TempUserCreator",
+				"UserFactory",
 				"SkinFactory"
 			]
 		},
diff --git a/includes/ApiDiscussionToolsEdit.php b/includes/ApiDiscussionToolsEdit.php
index df64cf218..e577d3f97 100644
--- a/includes/ApiDiscussionToolsEdit.php
+++ b/includes/ApiDiscussionToolsEdit.php
@@ -16,6 +16,8 @@ use MediaWiki\Logger\LoggerFactory;
 use MediaWiki\Request\DerivativeRequest;
 use MediaWiki\Revision\RevisionLookup;
 use MediaWiki\Title\Title;
+use MediaWiki\User\TempUser\TempUserCreator;
+use MediaWiki\User\UserFactory;
 use SkinFactory;
 use Wikimedia\ParamValidator\ParamValidator;
 use Wikimedia\ParamValidator\TypeDef\StringDef;
@@ -29,6 +31,8 @@ class ApiDiscussionToolsEdit extends ApiBase {
 	private CommentParser $commentParser;
 	private VisualEditorParsoidClientFactory $parsoidClientFactory;
 	private SubscriptionStore $subscriptionStore;
+	private TempUserCreator $tempUserCreator;
+	private UserFactory $userFactory;
 	private SkinFactory $skinFactory;
 	private Config $config;
 	private RevisionLookup $revisionLookup;
@@ -39,6 +43,8 @@ class ApiDiscussionToolsEdit extends ApiBase {
 		VisualEditorParsoidClientFactory $parsoidClientFactory,
 		CommentParser $commentParser,
 		SubscriptionStore $subscriptionStore,
+		TempUserCreator $tempUserCreator,
+		UserFactory $userFactory,
 		SkinFactory $skinFactory,
 		ConfigFactory $configFactory,
 		RevisionLookup $revisionLookup
@@ -47,6 +53,8 @@ class ApiDiscussionToolsEdit extends ApiBase {
 		$this->parsoidClientFactory = $parsoidClientFactory;
 		$this->commentParser = $commentParser;
 		$this->subscriptionStore = $subscriptionStore;
+		$this->tempUserCreator = $tempUserCreator;
+		$this->userFactory = $userFactory;
 		$this->skinFactory = $skinFactory;
 		$this->config = $configFactory->makeConfig( 'discussiontools' );
 		$this->revisionLookup = $revisionLookup;
@@ -107,7 +115,7 @@ class ApiDiscussionToolsEdit extends ApiBase {
 		$previewContainer = DOMCompat::getBody( DOMUtils::parseHTML( $previewResultHtml ) );
 		$previewThreadItemSet = $this->commentParser->parse( $previewContainer, $title->getTitleValue() );
 		if ( CommentUtils::isSingleCommentSignedBy(
-			$previewThreadItemSet, $this->getUser()->getName(), $previewContainer
+			$previewThreadItemSet, $this->getUserForPreview()->getName(), $previewContainer
 		) ) {
 			$signature = null;
 		} else {
diff --git a/includes/ApiDiscussionToolsPreview.php b/includes/ApiDiscussionToolsPreview.php
index ac84e9e4e..7f7707b67 100644
--- a/includes/ApiDiscussionToolsPreview.php
+++ b/includes/ApiDiscussionToolsPreview.php
@@ -8,6 +8,8 @@ use ApiUsageException;
 use MediaWiki\Extension\VisualEditor\ApiParsoidTrait;
 use MediaWiki\Extension\VisualEditor\VisualEditorParsoidClientFactory;
 use MediaWiki\Title\Title;
+use MediaWiki\User\TempUser\TempUserCreator;
+use MediaWiki\User\UserFactory;
 use SkinFactory;
 use Wikimedia\ParamValidator\ParamValidator;
 use Wikimedia\Parsoid\Utils\DOMCompat;
@@ -19,6 +21,8 @@ class ApiDiscussionToolsPreview extends ApiBase {
 
 	private CommentParser $commentParser;
 	private VisualEditorParsoidClientFactory $parsoidClientFactory;
+	private TempUserCreator $tempUserCreator;
+	private UserFactory $userFactory;
 	private SkinFactory $skinFactory;
 
 	public function __construct(
@@ -26,11 +30,15 @@ class ApiDiscussionToolsPreview extends ApiBase {
 		string $name,
 		VisualEditorParsoidClientFactory $parsoidClientFactory,
 		CommentParser $commentParser,
+		TempUserCreator $tempUserCreator,
+		UserFactory $userFactory,
 		SkinFactory $skinFactory
 	) {
 		parent::__construct( $main, $name );
 		$this->parsoidClientFactory = $parsoidClientFactory;
 		$this->commentParser = $commentParser;
+		$this->tempUserCreator = $tempUserCreator;
+		$this->userFactory = $userFactory;
 		$this->skinFactory = $skinFactory;
 	}
 
@@ -64,7 +72,9 @@ class ApiDiscussionToolsPreview extends ApiBase {
 		// Check if there was a signature in a proper place
 		$container = DOMCompat::getBody( DOMUtils::parseHTML( $resultHtml ) );
 		$threadItemSet = $this->commentParser->parse( $container, $title->getTitleValue() );
-		if ( !CommentUtils::isSingleCommentSignedBy( $threadItemSet, $this->getUser()->getName(), $container ) ) {
+		if ( !CommentUtils::isSingleCommentSignedBy(
+			$threadItemSet, $this->getUserForPreview()->getName(), $container
+		) ) {
 			// If not, add the signature and re-render
 			$signature = $this->msg( 'discussiontools-signature-prefix' )->inContentLanguage()->text() . '~~~~';
 			// Drop opacity of signature in preview to make message body preview clearer.
diff --git a/includes/ApiDiscussionToolsTrait.php b/includes/ApiDiscussionToolsTrait.php
index 5dc1765d8..8e99d5441 100644
--- a/includes/ApiDiscussionToolsTrait.php
+++ b/includes/ApiDiscussionToolsTrait.php
@@ -11,6 +11,10 @@ use MediaWiki\Extension\VisualEditor\VisualEditorParsoidClientFactory;
 use MediaWiki\Request\DerivativeRequest;
 use MediaWiki\Revision\RevisionRecord;
 use MediaWiki\Title\Title;
+use MediaWiki\User\TempUser\TempUserCreator;
+use MediaWiki\User\UserFactory;
+use User;
+use WebRequest;
 use Wikimedia\Parsoid\Utils\DOMCompat;
 use Wikimedia\Parsoid\Utils\DOMUtils;
 
@@ -19,6 +23,8 @@ use Wikimedia\Parsoid\Utils\DOMUtils;
  *
  * @property VisualEditorParsoidClientFactory $parsoidClientFactory
  * @property CommentParser $commentParser
+ * @property TempUserCreator $tempUserCreator
+ * @property UserFactory $userFactory
  */
 trait ApiDiscussionToolsTrait {
 
@@ -118,6 +124,20 @@ trait ApiDiscussionToolsTrait {
 		return $api->getResult();
 	}
 
+	/**
+	 * @see ApiParse::getUserForPreview
+	 * @return User
+	 */
+	private function getUserForPreview() {
+		$user = $this->getUser();
+		if ( $this->tempUserCreator->shouldAutoCreate( $user, 'edit' ) ) {
+			return $this->userFactory->newUnsavedTempUser(
+				$this->tempUserCreator->getStashedName( $this->getRequest()->getSession() )
+			);
+		}
+		return $user;
+	}
+
 	/**
 	 * @see VisualEditorParsoidClientFactory
 	 * @return ParsoidClient
@@ -153,4 +173,14 @@ trait ApiDiscussionToolsTrait {
 	 */
 	abstract public function getContext();
 
+	/**
+	 * @return User
+	 */
+	abstract public function getUser();
+
+	/**
+	 * @return WebRequest
+	 */
+	abstract public function getRequest();
+
 }
diff --git a/modules/dt.ui.ReplyWidget.js b/modules/dt.ui.ReplyWidget.js
index 05b391e52..eaf4fc1f1 100644
--- a/modules/dt.ui.ReplyWidget.js
+++ b/modules/dt.ui.ReplyWidget.js
@@ -799,14 +799,19 @@ ReplyWidget.prototype.preparePreview = function ( wikitext ) {
 	if ( !wikitext ) {
 		parsePromise = $.Deferred().resolve( null ).promise();
 	} else {
-		this.previewRequest = parsePromise = controller.getApi().post( {
-			action: 'discussiontoolspreview',
-			type: this.isNewTopic ? 'topic' : 'reply',
-			page: this.pageName,
-			wikitext: wikitext,
-			sectiontitle: title,
-			useskin: mw.config.get( 'skin' ),
-			mobileformat: OO.ui.isMobile()
+		// Acquire a temporary user username before previewing, so that signatures and
+		// user-related magic words display the temp user instead of IP user in the preview. (T331397)
+		parsePromise = mw.user.acquireTempUserName().then( function () {
+			widget.previewRequest = controller.getApi().post( {
+				action: 'discussiontoolspreview',
+				type: widget.isNewTopic ? 'topic' : 'reply',
+				page: widget.pageName,
+				wikitext: wikitext,
+				sectiontitle: title,
+				useskin: mw.config.get( 'skin' ),
+				mobileformat: OO.ui.isMobile()
+			} );
+			return widget.previewRequest;
 		} );
 	}