diff --git a/includes/ApiDiscussionToolsPageInfo.php b/includes/ApiDiscussionToolsPageInfo.php
index 09912e14e..02ba9a4b1 100644
--- a/includes/ApiDiscussionToolsPageInfo.php
+++ b/includes/ApiDiscussionToolsPageInfo.php
@@ -173,7 +173,7 @@ class ApiDiscussionToolsPageInfo extends ApiBase {
 			$closest = CommentUtils::closestElementWithSibling( $firstRange->startContainer, 'previous' );
 			if ( $closest && !$rootNode->isSameNode( $closest ) ) {
 				$range = new ImmutableRange( $rootNode, 0, $rootNode, 0 );
-				$fakeHeading = new ContentHeadingItem( $range, null );
+				$fakeHeading = new ContentHeadingItem( $range, false, null );
 				$fakeHeading->setRootNode( $rootNode );
 				$fakeHeading->setName( 'h-' );
 				$fakeHeading->setId( 'h-' );
diff --git a/includes/CommentParser.php b/includes/CommentParser.php
index d800c2c7d..865a149bb 100644
--- a/includes/CommentParser.php
+++ b/includes/CommentParser.php
@@ -15,6 +15,7 @@ use MediaWiki\Extension\DiscussionTools\ThreadItem\ContentHeadingItem;
 use MediaWiki\Extension\DiscussionTools\ThreadItem\ContentThreadItem;
 use MediaWiki\Languages\LanguageConverterFactory;
 use MediaWiki\Title\MalformedTitleException;
+use MediaWiki\Title\Title;
 use MediaWiki\Title\TitleParser;
 use MediaWiki\Title\TitleValue;
 use MediaWiki\Utils\MWTimestamp;
@@ -911,7 +912,8 @@ class CommentParser {
 				$range = new ImmutableRange(
 					$headingNode, $startOffset, $headingNode, $headingNode->childNodes->length
 				);
-				$curComment = new ContentHeadingItem( $range, (int)( $match[ 1 ] ) );
+				$transcludedFrom = $this->computeTranscludedFrom( $range );
+				$curComment = new ContentHeadingItem( $range, $transcludedFrom, (int)( $match[ 1 ] ) );
 				$curComment->setRootNode( $this->rootNode );
 				$result->addThreadItem( $curComment );
 				$curCommentEnd = $node;
@@ -989,6 +991,7 @@ class CommentParser {
 					$endNode,
 					$length
 				);
+				$transcludedFrom = $this->computeTranscludedFrom( $range );
 
 				$startLevel = CommentUtils::getIndentLevel( $startNode, $this->rootNode ) + 1;
 				$endLevel = CommentUtils::getIndentLevel( $node, $this->rootNode ) + 1;
@@ -1011,6 +1014,7 @@ class CommentParser {
 				$curComment = new ContentCommentItem(
 					$level,
 					$range,
+					$transcludedFrom,
 					$sigRanges,
 					$timestampRanges,
 					$dateTime,
@@ -1025,7 +1029,7 @@ class CommentParser {
 					// Add a fake placeholder heading if there are any comments in the 0th section
 					// (before the first real heading)
 					$range = new ImmutableRange( $this->rootNode, 0, $this->rootNode, 0 );
-					$fakeHeading = new ContentHeadingItem( $range, null );
+					$fakeHeading = new ContentHeadingItem( $range, false, null );
 					$fakeHeading->setRootNode( $this->rootNode );
 					$result->addThreadItem( $fakeHeading );
 				}
@@ -1037,6 +1041,217 @@ class CommentParser {
 		return $result;
 	}
 
+	/**
+	 * Get the name of the page from which this thread item is transcluded (if any). Replies to
+	 * transcluded items must be posted on that page, instead of the current one.
+	 *
+	 * This is tricky, because we don't want to mark items as trancluded when they're just using a
+	 * template (e.g. {{ping|…}} or a non-substituted signature template). Sometimes the whole comment
+	 * can be template-generated (e.g. when using some wrapper templates), but as long as a reply can
+	 * be added outside of that template, we should not treat it as transcluded.
+	 *
+	 * The start/end boundary points of comment ranges and Parsoid transclusion ranges don't line up
+	 * exactly, even when to a human it's obvious that they cover the same content, making this more
+	 * complicated.
+	 *
+	 * @return string|bool `false` if this item is not transcluded. A string if it's transcluded
+	 *   from a single page (the page title, in text form with spaces). `true` if it's transcluded, but
+	 *   we can't determine the source.
+	 */
+	public function computeTranscludedFrom( ImmutableRange $commentRange ) {
+		// Collapsed ranges should otherwise be impossible, but they're not (T299583)
+		// TODO: See if we can fix the root cause, and remove this?
+		if ( $commentRange->collapsed ) {
+			return false;
+		}
+
+		// General approach:
+		//
+		// Compare the comment range to each transclusion range on the page, and if it overlaps any of
+		// them, examine the overlap. There are a few cases:
+		//
+		// * Comment and transclusion do not overlap:
+		//   → Not transcluded.
+		// * Comment contains the transclusion:
+		//   → Not transcluded (just a template).
+		// * Comment is contained within the transclusion:
+		//   → Transcluded, we can determine the source page (unless it's a complex transclusion).
+		// * Comment and transclusion overlap partially:
+		//   → Transcluded, but we can't determine the source page.
+		// * Comment (almost) exactly matches the transclusion:
+		//   → Maybe transcluded (it could be that the source page only contains that single comment),
+		//     maybe not transcluded (it could be a wrapper template that covers a single comment).
+		//     This is very sad, and we decide based on the namespace.
+		//
+		// Most transclusion ranges on the page trivially fall in the "do not overlap" or "contains"
+		// cases, and we only have to carefully examine the two transclusion ranges that contain the
+		// first and last node of the comment range.
+		//
+		// To check for almost exact matches, we walk between the relevant boundary points, and if we
+		// only find uninteresting nodes (that would be ignored when detecting comments), we treat them
+		// like exact matches.
+
+		$startTransclNode = CommentUtils::getTranscludedFromElement(
+			CommentUtils::getRangeFirstNode( $commentRange )
+		);
+		$endTransclNode = CommentUtils::getTranscludedFromElement(
+			CommentUtils::getRangeLastNode( $commentRange )
+		);
+
+		// We only have to examine the two transclusion ranges that contain the first/last node of the
+		// comment range (if they exist). Ignore ranges outside the comment or in the middle of it.
+		$transclNodes = [];
+		if ( $startTransclNode ) {
+			$transclNodes[] = $startTransclNode;
+		}
+		if ( $endTransclNode && $endTransclNode !== $startTransclNode ) {
+			$transclNodes[] = $endTransclNode;
+		}
+
+		foreach ( $transclNodes as $transclNode ) {
+			$transclRange = static::getTransclusionRange( $transclNode );
+			$compared = CommentUtils::compareRanges( $commentRange, $transclRange );
+			$transclTitles = $this->getTransclusionTitles( $transclNode );
+			$simpleTransclTitle = count( $transclTitles ) === 1 ? $transclTitles[0] : null;
+
+			switch ( $compared ) {
+				case 'equal':
+					// Comment (almost) exactly matches the transclusion
+					if ( $simpleTransclTitle === null ) {
+						// Allow replying to some accidental complex transclusions consisting of only templates
+						// and wikitext (T313093)
+						if ( count( $transclTitles ) > 1 ) {
+							foreach ( $transclTitles as $transclTitle ) {
+								if ( $transclTitle && !$transclTitle->inNamespace( NS_TEMPLATE ) ) {
+									return true;
+								}
+							}
+							// Continue examining the other ranges.
+							break;
+						}
+						// Multi-template transclusion, or a parser function call, or template-affected wikitext outside
+						// of a template call, or a mix of the above
+						return true;
+
+					} elseif ( $simpleTransclTitle->inNamespace( NS_TEMPLATE ) ) {
+						// Is that a subpage transclusion with a single comment, or a wrapper template
+						// transclusion on this page? We don't know, but let's guess based on the namespace.
+						// (T289873)
+						// Continue examining the other ranges.
+						break;
+					} elseif ( !$simpleTransclTitle->canExist() ) {
+						// Special page transclusion, probably accidental (T344622). Don't return the title,
+						// since it's useless for replying, and can't be stored in the permalink database.
+						return true;
+					} else {
+						return $simpleTransclTitle->getPrefixedText();
+					}
+
+				case 'contains':
+					// Comment contains the transclusion
+
+					// If the entire transclusion is contained within the comment range, that's just a
+					// template. This is the same as a transclusion in the middle of the comment, which we
+					// ignored earlier, it just takes us longer to get here in this case.
+
+					// Continue examining the other ranges.
+					break;
+
+				case 'contained':
+					// Comment is contained within the transclusion
+					if ( $simpleTransclTitle === null ) {
+						return true;
+					} elseif ( !$simpleTransclTitle->canExist() ) {
+						// Special page transclusion, probably accidental (T344622). Don't return the title,
+						// since it's useless for replying, and can't be stored in the permalink database.
+						return true;
+					} else {
+						return $simpleTransclTitle->getPrefixedText();
+					}
+
+				case 'after':
+				case 'before':
+					// Comment and transclusion do not overlap
+
+					// This should be impossible, because we ignored these ranges earlier.
+					throw new LogicException( 'Unexpected transclusion or comment range' );
+
+				case 'overlapstart':
+				case 'overlapend':
+					// Comment and transclusion overlap partially
+					return true;
+
+				default:
+					throw new LogicException( 'Unexpected return value from compareRanges()' );
+			}
+		}
+
+		// If we got here, the comment range was not contained by or overlapping any of the transclusion
+		// ranges. Comment is not transcluded.
+		return false;
+	}
+
+	/**
+	 * Return the page titles for each part of the transclusion, or nulls for each part that isn't
+	 * transcluded from another page.
+	 *
+	 * If the node represents a single-page transclusion, this will return an array containing a
+	 * single Title object.
+	 *
+	 * @param Element $node
+	 * @return (?Title)[]
+	 */
+	private function getTransclusionTitles( Element $node ): array {
+		$dataMw = json_decode( $node->getAttribute( 'data-mw' ) ?? '', true );
+		$out = [];
+
+		foreach ( $dataMw['parts'] ?? [] as $part ) {
+			if (
+				!is_string( $part ) &&
+				// 'href' will be unset if this is a parser function rather than a template
+				isset( $part['template']['target']['href'] )
+			) {
+				$parsoidHref = $part['template']['target']['href'];
+				Assert::precondition( substr( $parsoidHref, 0, 2 ) === './', "href has valid format" );
+				$out[] = Title::newFromText( urldecode( substr( $parsoidHref, 2 ) ) );
+			} else {
+				$out[] = null;
+			}
+		}
+
+		return $out;
+	}
+
+	/**
+	 * Given a transclusion's first node (e.g. returned by CommentUtils::getTranscludedFromElement()),
+	 * return a range starting before the node and ending after the transclusion's last node.
+	 *
+	 * @param Element $startNode
+	 * @return ImmutableRange
+	 */
+	private function getTransclusionRange( Element $startNode ): ImmutableRange {
+		$endNode = $startNode;
+		while (
+			// Phan doesn't realize that the conditions on $nextSibling can terminate the loop
+			// @phan-suppress-next-line PhanInfiniteLoop
+			$endNode &&
+			( $nextSibling = $endNode->nextSibling ) &&
+			$nextSibling instanceof Element &&
+			$nextSibling->getAttribute( 'about' ) === $endNode->getAttribute( 'about' )
+		) {
+			$endNode = $nextSibling;
+		}
+
+		$range = new ImmutableRange(
+			$startNode->parentNode,
+			CommentUtils::childIndexOf( $startNode ),
+			$endNode->parentNode,
+			CommentUtils::childIndexOf( $endNode ) + 1
+		);
+
+		return $range;
+	}
+
 	/**
 	 * Truncate user generated parts of IDs so full ID always fits within a database field of length 255
 	 *
diff --git a/includes/ThreadItem/ContentCommentItem.php b/includes/ThreadItem/ContentCommentItem.php
index eff57b86a..cc73fa340 100644
--- a/includes/ThreadItem/ContentCommentItem.php
+++ b/includes/ThreadItem/ContentCommentItem.php
@@ -32,6 +32,7 @@ class ContentCommentItem extends ContentThreadItem implements CommentItem {
 	/**
 	 * @param int $level
 	 * @param ImmutableRange $range
+	 * @param bool|string $transcludedFrom
 	 * @param ImmutableRange[] $signatureRanges Objects describing the extent of signatures (plus
 	 *  timestamps) for this comment. There is always at least one signature, but there may be
 	 *  multiple. The author and timestamp of the comment is determined from the first signature.
@@ -42,12 +43,12 @@ class ContentCommentItem extends ContentThreadItem implements CommentItem {
 	 * @param ?string $displayName Comment author's display name
 	 */
 	public function __construct(
-		int $level, ImmutableRange $range,
+		int $level, ImmutableRange $range, $transcludedFrom,
 		array $signatureRanges, array $timestampRanges,
 		DateTimeImmutable $timestamp,
 		string $author, ?string $displayName = null
 	) {
-		parent::__construct( 'comment', $level, $range );
+		parent::__construct( 'comment', $level, $range, $transcludedFrom );
 		$this->signatureRanges = $signatureRanges;
 		$this->timestampRanges = $timestampRanges;
 		$this->timestamp = $timestamp;
diff --git a/includes/ThreadItem/ContentHeadingItem.php b/includes/ThreadItem/ContentHeadingItem.php
index 5581295e2..b01e5acad 100644
--- a/includes/ThreadItem/ContentHeadingItem.php
+++ b/includes/ThreadItem/ContentHeadingItem.php
@@ -20,12 +20,13 @@ class ContentHeadingItem extends ContentThreadItem implements HeadingItem {
 
 	/**
 	 * @param ImmutableRange $range
+	 * @param bool|string $transcludedFrom
 	 * @param ?int $headingLevel Heading level (1-6). Use null for a placeholder heading.
 	 */
 	public function __construct(
-		ImmutableRange $range, ?int $headingLevel
+		ImmutableRange $range, $transcludedFrom, ?int $headingLevel
 	) {
-		parent::__construct( 'heading', 0, $range );
+		parent::__construct( 'heading', 0, $range, $transcludedFrom );
 		$this->placeholderHeading = $headingLevel === null;
 		$this->headingLevel = $this->placeholderHeading ? static::PLACEHOLDER_HEADING_LEVEL : $headingLevel;
 	}
@@ -97,22 +98,6 @@ class ContentHeadingItem extends ContentThreadItem implements HeadingItem {
 		$this->placeholderHeading = $placeholderHeading;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	public function getTranscludedFrom() {
-		// Placeholder headings break the usual logic, because their ranges are collapsed
-		if ( $this->isPlaceholderHeading() ) {
-			return false;
-		}
-		// Collapsed ranges should otherwise be impossible, but they're not (T299583)
-		// TODO: See if we can fix the root cause, and remove this?
-		if ( $this->getRange()->collapsed ) {
-			return false;
-		}
-		return parent::getTranscludedFrom();
-	}
-
 	/**
 	 * @inheritDoc
 	 */
diff --git a/includes/ThreadItem/ContentThreadItem.php b/includes/ThreadItem/ContentThreadItem.php
index 9fb90c292..6bd639e94 100644
--- a/includes/ThreadItem/ContentThreadItem.php
+++ b/includes/ThreadItem/ContentThreadItem.php
@@ -3,13 +3,9 @@
 namespace MediaWiki\Extension\DiscussionTools\ThreadItem;
 
 use JsonSerializable;
-use LogicException;
 use MediaWiki\Extension\DiscussionTools\CommentModifier;
-use MediaWiki\Extension\DiscussionTools\CommentUtils;
 use MediaWiki\Extension\DiscussionTools\ImmutableRange;
 use MediaWiki\Parser\Sanitizer;
-use MediaWiki\Title\Title;
-use Wikimedia\Assert\Assert;
 use Wikimedia\Parsoid\DOM\Element;
 use Wikimedia\Parsoid\Utils\DOMUtils;
 
@@ -31,6 +27,8 @@ abstract class ContentThreadItem implements JsonSerializable, ThreadItem {
 	protected string $id;
 	/** @var ContentThreadItem[] */
 	protected array $replies = [];
+	/** @var string|bool */
+	private $transcludedFrom;
 
 	/** @var ?array[] */
 	protected ?array $authors = null;
@@ -43,13 +41,15 @@ abstract class ContentThreadItem implements JsonSerializable, ThreadItem {
 	 * @param int $level Indentation level
 	 * @param ImmutableRange $range Object describing the extent of the comment, including the
 	 *  signature and timestamp.
+	 * @param bool|string $transcludedFrom
 	 */
 	public function __construct(
-		string $type, int $level, ImmutableRange $range
+		string $type, int $level, ImmutableRange $range, $transcludedFrom
 	) {
 		$this->type = $type;
 		$this->level = $level;
 		$this->range = $range;
+		$this->transcludedFrom = $transcludedFrom;
 	}
 
 	/**
@@ -172,209 +172,10 @@ abstract class ContentThreadItem implements JsonSerializable, ThreadItem {
 	}
 
 	/**
-	 * Get the name of the page from which this thread item is transcluded (if any). Replies to
-	 * transcluded items must be posted on that page, instead of the current one.
-	 *
-	 * This is tricky, because we don't want to mark items as trancluded when they're just using a
-	 * template (e.g. {{ping|…}} or a non-substituted signature template). Sometimes the whole comment
-	 * can be template-generated (e.g. when using some wrapper templates), but as long as a reply can
-	 * be added outside of that template, we should not treat it as transcluded.
-	 *
-	 * The start/end boundary points of comment ranges and Parsoid transclusion ranges don't line up
-	 * exactly, even when to a human it's obvious that they cover the same content, making this more
-	 * complicated.
-	 *
-	 * @return string|bool `false` if this item is not transcluded. A string if it's transcluded
-	 *   from a single page (the page title, in text form with spaces). `true` if it's transcluded, but
-	 *   we can't determine the source.
+	 * @inheritDoc
 	 */
 	public function getTranscludedFrom() {
-		// General approach:
-		//
-		// Compare the comment range to each transclusion range on the page, and if it overlaps any of
-		// them, examine the overlap. There are a few cases:
-		//
-		// * Comment and transclusion do not overlap:
-		//   → Not transcluded.
-		// * Comment contains the transclusion:
-		//   → Not transcluded (just a template).
-		// * Comment is contained within the transclusion:
-		//   → Transcluded, we can determine the source page (unless it's a complex transclusion).
-		// * Comment and transclusion overlap partially:
-		//   → Transcluded, but we can't determine the source page.
-		// * Comment (almost) exactly matches the transclusion:
-		//   → Maybe transcluded (it could be that the source page only contains that single comment),
-		//     maybe not transcluded (it could be a wrapper template that covers a single comment).
-		//     This is very sad, and we decide based on the namespace.
-		//
-		// Most transclusion ranges on the page trivially fall in the "do not overlap" or "contains"
-		// cases, and we only have to carefully examine the two transclusion ranges that contain the
-		// first and last node of the comment range.
-		//
-		// To check for almost exact matches, we walk between the relevant boundary points, and if we
-		// only find uninteresting nodes (that would be ignored when detecting comments), we treat them
-		// like exact matches.
-
-		$commentRange = $this->getRange();
-		$startTransclNode = CommentUtils::getTranscludedFromElement(
-			CommentUtils::getRangeFirstNode( $commentRange )
-		);
-		$endTransclNode = CommentUtils::getTranscludedFromElement(
-			CommentUtils::getRangeLastNode( $commentRange )
-		);
-
-		// We only have to examine the two transclusion ranges that contain the first/last node of the
-		// comment range (if they exist). Ignore ranges outside the comment or in the middle of it.
-		$transclNodes = [];
-		if ( $startTransclNode ) {
-			$transclNodes[] = $startTransclNode;
-		}
-		if ( $endTransclNode && $endTransclNode !== $startTransclNode ) {
-			$transclNodes[] = $endTransclNode;
-		}
-
-		foreach ( $transclNodes as $transclNode ) {
-			$transclRange = static::getTransclusionRange( $transclNode );
-			$compared = CommentUtils::compareRanges( $commentRange, $transclRange );
-			$transclTitles = $this->getTransclusionTitles( $transclNode );
-			$simpleTransclTitle = count( $transclTitles ) === 1 ? $transclTitles[0] : null;
-
-			switch ( $compared ) {
-				case 'equal':
-					// Comment (almost) exactly matches the transclusion
-					if ( $simpleTransclTitle === null ) {
-						// Allow replying to some accidental complex transclusions consisting of only templates
-						// and wikitext (T313093)
-						if ( count( $transclTitles ) > 1 ) {
-							foreach ( $transclTitles as $transclTitle ) {
-								if ( $transclTitle && !$transclTitle->inNamespace( NS_TEMPLATE ) ) {
-									return true;
-								}
-							}
-							// Continue examining the other ranges.
-							break;
-						}
-						// Multi-template transclusion, or a parser function call, or template-affected wikitext outside
-						// of a template call, or a mix of the above
-						return true;
-
-					} elseif ( $simpleTransclTitle->inNamespace( NS_TEMPLATE ) ) {
-						// Is that a subpage transclusion with a single comment, or a wrapper template
-						// transclusion on this page? We don't know, but let's guess based on the namespace.
-						// (T289873)
-						// Continue examining the other ranges.
-						break;
-					} elseif ( !$simpleTransclTitle->canExist() ) {
-						// Special page transclusion, probably accidental (T344622). Don't return the title,
-						// since it's useless for replying, and can't be stored in the permalink database.
-						return true;
-					} else {
-						return $simpleTransclTitle->getPrefixedText();
-					}
-
-				case 'contains':
-					// Comment contains the transclusion
-
-					// If the entire transclusion is contained within the comment range, that's just a
-					// template. This is the same as a transclusion in the middle of the comment, which we
-					// ignored earlier, it just takes us longer to get here in this case.
-
-					// Continue examining the other ranges.
-					break;
-
-				case 'contained':
-					// Comment is contained within the transclusion
-					if ( $simpleTransclTitle === null ) {
-						return true;
-					} elseif ( !$simpleTransclTitle->canExist() ) {
-						// Special page transclusion, probably accidental (T344622). Don't return the title,
-						// since it's useless for replying, and can't be stored in the permalink database.
-						return true;
-					} else {
-						return $simpleTransclTitle->getPrefixedText();
-					}
-
-				case 'after':
-				case 'before':
-					// Comment and transclusion do not overlap
-
-					// This should be impossible, because we ignored these ranges earlier.
-					throw new LogicException( 'Unexpected transclusion or comment range' );
-
-				case 'overlapstart':
-				case 'overlapend':
-					// Comment and transclusion overlap partially
-					return true;
-
-				default:
-					throw new LogicException( 'Unexpected return value from compareRanges()' );
-			}
-		}
-
-		// If we got here, the comment range was not contained by or overlapping any of the transclusion
-		// ranges. Comment is not transcluded.
-		return false;
-	}
-
-	/**
-	 * Return the page titles for each part of the transclusion, or nulls for each part that isn't
-	 * transcluded from another page.
-	 *
-	 * If the node represents a single-page transclusion, this will return an array containing a
-	 * single Title object.
-	 *
-	 * @param Element $node
-	 * @return (?Title)[]
-	 */
-	private function getTransclusionTitles( Element $node ): array {
-		$dataMw = json_decode( $node->getAttribute( 'data-mw' ) ?? '', true );
-		$out = [];
-
-		foreach ( $dataMw['parts'] ?? [] as $part ) {
-			if (
-				!is_string( $part ) &&
-				// 'href' will be unset if this is a parser function rather than a template
-				isset( $part['template']['target']['href'] )
-			) {
-				$parsoidHref = $part['template']['target']['href'];
-				Assert::precondition( substr( $parsoidHref, 0, 2 ) === './', "href has valid format" );
-				$out[] = Title::newFromText( urldecode( substr( $parsoidHref, 2 ) ) );
-			} else {
-				$out[] = null;
-			}
-		}
-
-		return $out;
-	}
-
-	/**
-	 * Given a transclusion's first node (e.g. returned by CommentUtils::getTranscludedFromElement()),
-	 * return a range starting before the node and ending after the transclusion's last node.
-	 *
-	 * @param Element $startNode
-	 * @return ImmutableRange
-	 */
-	private function getTransclusionRange( Element $startNode ): ImmutableRange {
-		$endNode = $startNode;
-		while (
-			// Phan doesn't realize that the conditions on $nextSibling can terminate the loop
-			// @phan-suppress-next-line PhanInfiniteLoop
-			$endNode &&
-			( $nextSibling = $endNode->nextSibling ) &&
-			$nextSibling instanceof Element &&
-			$nextSibling->getAttribute( 'about' ) === $endNode->getAttribute( 'about' )
-		) {
-			$endNode = $nextSibling;
-		}
-
-		$range = new ImmutableRange(
-			$startNode->parentNode,
-			CommentUtils::childIndexOf( $startNode ),
-			$endNode->parentNode,
-			CommentUtils::childIndexOf( $endNode ) + 1
-		);
-
-		return $range;
+		return $this->transcludedFrom;
 	}
 
 	/**
diff --git a/tests/phpunit/ContentThreadItemTest.php b/tests/phpunit/ContentThreadItemTest.php
index b6c8b2934..ba8f3296e 100644
--- a/tests/phpunit/ContentThreadItemTest.php
+++ b/tests/phpunit/ContentThreadItemTest.php
@@ -32,12 +32,12 @@ class ContentThreadItemTest extends IntegrationTestCase {
 		$makeThreadItem = static function ( array $arr ) use ( &$makeThreadItem, $range ): ContentThreadItem {
 			if ( $arr['type'] === 'comment' ) {
 				$item = new ContentCommentItem(
-					1, $range, [], [], new DateTimeImmutable(),
+					1, $range, false, [], [], new DateTimeImmutable(),
 					$arr['author'],
 					$arr['displayName'] ?? null
 				);
 			} else {
-				$item = new ContentHeadingItem( $range, 2 );
+				$item = new ContentHeadingItem( $range, false, 2 );
 			}
 			$item->setId( $arr['id'] );
 			foreach ( $arr['replies'] as $reply ) {