From d4628e78d45b5abcbba5a435a71b01fa10d30e1a Mon Sep 17 00:00:00 2001
From: Michael Telatynski <7t3chguy@gmail.com>
Date: Thu, 13 Jul 2023 09:25:23 +0100
Subject: [PATCH] Fix read receipt sending behaviour around thread roots
 (#3600)

* Fix read receipt sending behaviour around thread roots

* Update src/client.ts

Co-authored-by: Eric Eastwood <erice@element.io>

---------

Co-authored-by: Eric Eastwood <erice@element.io>
(cherry picked from commit b05f933d833ef6c9b2a8ff7a8b27723b682bcce6)
---
 src/client.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/client.ts b/src/client.ts
index 9d9e1d3aa..40fe51daa 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -4992,9 +4992,11 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         });
 
         if (!unthreaded) {
-            const isThread = !!event.threadRootId;
+            // A thread cannot be just a thread root and a thread root can only be read in the main timeline
+            const isThread = !!event.threadRootId && !event.isThreadRoot;
             body = {
                 ...body,
+                // Only thread replies should define a specific thread. Thread roots can only be read in the main timeline.
                 thread_id: isThread ? event.threadRootId : MAIN_ROOM_TIMELINE,
             };
         }