From d215354e6482c9c0fce12295bf9672a0948fef7a Mon Sep 17 00:00:00 2001
From: Jorge Martin Espinosa <jorgem@element.io>
Date: Wed, 29 Apr 2026 12:54:03 +0200
Subject: [PATCH] Remove legacy `mx-reply` from `toPlainText` formatted event
 contents (#6683)

---
 .../matrix/ui/messages/ToHtmlDocument.kt      | 40 +++++++++++++++++--
 .../matrix/ui/messages/ToPlainText.kt         |  5 +++
 .../matrix/ui/messages/ToPlainTextTest.kt     | 15 +++++++
 3 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/ToHtmlDocument.kt b/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/ToHtmlDocument.kt
index ee9de51681..d29a28cba9 100644
--- a/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/ToHtmlDocument.kt
+++ b/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/ToHtmlDocument.kt
@@ -12,8 +12,10 @@ import io.element.android.libraries.matrix.api.permalink.PermalinkData
 import io.element.android.libraries.matrix.api.permalink.PermalinkParser
 import io.element.android.libraries.matrix.api.timeline.item.event.FormattedBody
 import io.element.android.libraries.matrix.api.timeline.item.event.MessageFormat
-import io.element.android.wysiwyg.utils.HtmlToDomParser
+import org.jsoup.Jsoup
 import org.jsoup.nodes.Document
+import org.jsoup.nodes.Document.OutputSettings
+import org.jsoup.safety.Safelist
 
 /**
  * Converts the HTML string [FormattedBody.body] to a [Document] by parsing it.
@@ -34,9 +36,9 @@ fun FormattedBody.toHtmlDocument(
         ?.trimEnd()
         ?.let { formattedBody ->
             val dom = if (prefix != null) {
-                HtmlToDomParser.document("$prefix $formattedBody")
+                CustomHtmlToDomParser.document("$prefix $formattedBody")
             } else {
-                HtmlToDomParser.document(formattedBody)
+                CustomHtmlToDomParser.document(formattedBody)
             }
 
             // Prepend `@` to mentions
@@ -60,3 +62,35 @@ private fun fixMentions(
         }
     }
 }
+
+/** Custom Html to DOM parser, based on the one included in the rich text editor library. */
+private object CustomHtmlToDomParser {
+    fun document(html: String): Document {
+        val outputSettings = OutputSettings().prettyPrint(false).indentAmount(0)
+        val cleanHtml = Jsoup.clean(html, "", safeList, outputSettings)
+        return Jsoup.parse(cleanHtml)
+    }
+
+    private val safeList = Safelist()
+        .addTags(
+            "a",
+            "b",
+            "strong",
+            "i",
+            "em",
+            "u",
+            "del",
+            "code",
+            "ul",
+            "ol",
+            "li",
+            "pre",
+            "blockquote",
+            "p",
+            "br",
+            // Add custom `mx-reply` tag, even if it's just to remove its contents from the plain text version of the message
+            "mx-reply"
+        )
+        .addAttributes("a", "href", "data-mention-type", "contenteditable")
+        .addAttributes("ol", "start")
+}
diff --git a/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/ToPlainText.kt b/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/ToPlainText.kt
index 34dc72aa1a..cf8b03b80d 100644
--- a/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/ToPlainText.kt
+++ b/libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/ToPlainText.kt
@@ -65,6 +65,8 @@ fun Document.toPlainText(): String {
     return visitor.build()
 }
 
+private const val FALLBACK_REPLY_NODE_TAG = "mx-reply"
+
 private class PlainTextNodeVisitor : NodeVisitor {
     private val builder = StringBuilder()
 
@@ -92,6 +94,9 @@ private class PlainTextNodeVisitor : NodeVisitor {
             } else {
                 builder.append("• ")
             }
+        } else if (node is Element && node.tagName() == FALLBACK_REPLY_NODE_TAG) {
+            // Remove the fallback reply node and its contents so they aren't added to the plain text message
+            node.remove()
         } else if (node is Element && node.isBlock && builder.lastOrNull() != '\n') {
             builder.append("\n")
         }
diff --git a/libraries/matrixui/src/test/kotlin/io/element/android/libraries/matrix/ui/messages/ToPlainTextTest.kt b/libraries/matrixui/src/test/kotlin/io/element/android/libraries/matrix/ui/messages/ToPlainTextTest.kt
index 607f825401..ce0ef4cf31 100644
--- a/libraries/matrixui/src/test/kotlin/io/element/android/libraries/matrix/ui/messages/ToPlainTextTest.kt
+++ b/libraries/matrixui/src/test/kotlin/io/element/android/libraries/matrix/ui/messages/ToPlainTextTest.kt
@@ -136,4 +136,19 @@ class ToPlainTextTest {
         )
         assertThat(messageType.toPlainText(permalinkParser = FakePermalinkParser())).isEqualTo("This is the fallback text")
     }
+
+    @Test
+    fun `TextMessageType toPlainText - ignores mx-reply element`() {
+        val messageType = TextMessageType(
+            body = "This is the fallback text",
+            formatted = FormattedBody(
+                format = MessageFormat.HTML,
+                body = """
+                    <mx-reply>In reply to...</mx-reply>
+                    This is the message content.
+                """.trimIndent()
+            )
+        )
+        assertThat(messageType.toPlainText(permalinkParser = FakePermalinkParser())).isEqualTo("This is the message content.")
+    }
 }