The thread panel resolves edits (getEditedEvent) and reactions (getEventReactions) against the thread's timeline set for every event including the root. Per Room.eventShouldLiveIn (matrix-js-sdk room.js:2110), a non-thread relation whose parent is a thread root lives only in the main room timeline — so edits and reactions targeting the root are never in the thread's timeline set. Result: after editing a thread root, the thread panel keeps showing the pre-edit text with no "(edited)" marker; reactions added to the root in the main timeline don't appear in the panel. Clicking the same emoji from inside the panel also can't find your existing reaction (myReaction lookup misses) and sends a duplicate m.reaction instead of toggling it off.
How to trigger
Start a thread, edit the root message and react to it from the main timeline, then open the thread panel.
Suggested fix
For the root event only (and any event whose relations live in the room), read edits/reactions from room.getUnfilteredTimelineSet(); the simplest fix is to pass mEventId === thread.id ? room.getUnfilteredTimelineSet() : thread.getUnfilteredTimelineSet() into getEditedEvent/getEventReactions/handleReactionToggle.
Filed from the September 2026 client audit (branch lotus @ 4bea4895).
**Severity:** high · **Type:** bug · **Confidence:** high
**Location:** `src/app/features/room/thread/ThreadTimeline.tsx:718` (`thread.getUnfilteredTimelineSet()`), `:660-680` (`renderMessageContent`), `:551-570` (`handleReactionToggle`)
### Problem
The thread panel resolves edits (`getEditedEvent`) and reactions (`getEventReactions`) against the **thread's** timeline set for every event including the root. Per `Room.eventShouldLiveIn` (matrix-js-sdk `room.js:2110`), a non-thread relation whose parent is a thread root lives **only in the main room timeline** — so edits and reactions targeting the root are never in the thread's timeline set. Result: after editing a thread root, the thread panel keeps showing the pre-edit text with no "(edited)" marker; reactions added to the root in the main timeline don't appear in the panel. Clicking the same emoji from inside the panel also can't find your existing reaction (`myReaction` lookup misses) and sends a duplicate `m.reaction` instead of toggling it off.
### How to trigger
Start a thread, edit the root message and react to it from the main timeline, then open the thread panel.
### Suggested fix
For the root event only (and any event whose relations live in the room), read edits/reactions from `room.getUnfilteredTimelineSet()`; the simplest fix is to pass `mEventId === thread.id ? room.getUnfilteredTimelineSet() : thread.getUnfilteredTimelineSet()` into `getEditedEvent`/`getEventReactions`/`handleReactionToggle`.
---
_Filed from the September 2026 client audit (branch `lotus` @ 4bea4895)._
jared
added this to the Audit 2026-09 · High milestone 2026-09-12 01:50:49 -04:00
Blocking a user prevents them from interacting with repositories, such as opening or commenting on pull requests or issues. Learn more about blocking a user.
Severity: high · Type: bug · Confidence: high
Location:
src/app/features/room/thread/ThreadTimeline.tsx:718(thread.getUnfilteredTimelineSet()),:660-680(renderMessageContent),:551-570(handleReactionToggle)Problem
The thread panel resolves edits (
getEditedEvent) and reactions (getEventReactions) against the thread's timeline set for every event including the root. PerRoom.eventShouldLiveIn(matrix-js-sdkroom.js:2110), a non-thread relation whose parent is a thread root lives only in the main room timeline — so edits and reactions targeting the root are never in the thread's timeline set. Result: after editing a thread root, the thread panel keeps showing the pre-edit text with no "(edited)" marker; reactions added to the root in the main timeline don't appear in the panel. Clicking the same emoji from inside the panel also can't find your existing reaction (myReactionlookup misses) and sends a duplicatem.reactioninstead of toggling it off.How to trigger
Start a thread, edit the root message and react to it from the main timeline, then open the thread panel.
Suggested fix
For the root event only (and any event whose relations live in the room), read edits/reactions from
room.getUnfilteredTimelineSet(); the simplest fix is to passmEventId === thread.id ? room.getUnfilteredTimelineSet() : thread.getUnfilteredTimelineSet()intogetEditedEvent/getEventReactions/handleReactionToggle.Filed from the September 2026 client audit (branch
lotus@4bea4895).