feat(threads): thread drawer, thread browser, live reply counts, and unread badges by Just-Insane · Pull Request #564 · SableClient/Sable

Just-Insane · 2026-03-28T01:29:43Z

📝 Docs: Already live at Threads — Sable Docs — no separate docs PR needed.

Description

Expands Matrix thread support with a full thread drawer, server-side thread browser, live reply counts, unread badges, and several UX fixes.

ThreadDrawer

Slide-in drawer for reading and replying in threads without leaving the main room
Thread root message shown at top with full reply history below
Up-arrow edit-last-message: pressing ↑ in the thread input edits the user's last own message in that thread
Reactions add/remove trigger immediate re-renders without manual refresh (handles the fact that reaction events carry m.relates_to.event_id not threadRootId directly — fetches target event to check thread membership)
Thread root message box sized to content with maxHeight: 200px to avoid dead whitespace on short messages

ThreadBrowser

Lists all threads in the room; calls room.fetchRoomThreads() on mount to load threads beyond the local timeline window
Load-more button when the server has additional thread pages
Each thread preview shows sender avatar, display name, reply count, and last message body with ellipsis truncation
Jump button navigates to the thread root in the main timeline (via useRoomNavigate) instead of re-opening the drawer
Thread unread badges on each preview item via room.getThreadUnreadNotificationCount()

ThreadReplyChip (main timeline)

Shows unread badge for threads with unseen replies via room.getThreadUnreadNotificationCount()

Thread button (RoomViewHeader)

If a thread drawer is open, button closes the drawer and opens the thread browser (allows going from a single thread to the full list)
If no thread is open, button toggles the thread browser as before
aria-pressed reflects both thread browser state and open thread drawer

Fixes #

Type of change

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected)
This change requires a documentation update

Checklist:

My code follows the style guidelines of this project
I have performed a self-review of my own code
I have commented my code, particularly in hard-to-understand areas
I have made corresponding changes to the documentation
My changes generate no new warnings

AI disclosure:

Partially AI assisted (clarify which code was AI assisted and briefly explain what it does)
Fully AI generated (explain what all the generated code does in moderate detail)

ThreadDrawer/ThreadBrowser/thread-chip iterations were partially AI assisted; I reviewed and adjusted logic for timeline processing, thread loading, and event rendering behavior.

Copilot

Pull request overview

Adds end-to-end Matrix thread support across the room timeline: a thread drawer for reading/replying in-thread, a thread browser listing room threads (with pagination), and live reply/unread indicators, backed by Matrix SDK threadSupport.

Changes:

Enable SDK thread tracking by passing threadSupport: true to startClient (classic + sliding sync).
Introduce shared edit-mode hook (useMessageEdit) and wire it through RoomTimeline/timeline actions and ThreadDrawer.
Implement thread UI primitives: ThreadDrawer ported to the shared timeline rendering pipeline, ThreadBrowser backed by /threads + pagination/backfill, and live reply/unread badges on timeline thread chips.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/client/initMatrix.ts	Enables Matrix SDK thread support in both classic and sliding sync start paths.
src/app/hooks/useMessageEdit.ts	New hook to centralize edit-mode state/reset/focus behavior for composers.
src/app/hooks/timeline/useTimelineEventRenderer.tsx	Adds live thread reply/unread chip updates; supports suppressing thread chip/reply headers inside drawer.
src/app/hooks/timeline/useTimelineActions.ts	Refactors timeline actions to accept shared `handleEdit` instead of owning edit state.
src/app/hooks/timeline/useProcessedTimeline.ts	Adds `skipThreadFilter` to allow processing thread timelines without filtering out replies.
src/app/features/room/ThreadDrawer.tsx	Reworks thread drawer to use shared timeline processing/rendering; adds sequential loading/backfill and edit-last-message support.
src/app/features/room/ThreadBrowser.tsx	Adds server-backed thread list with load-more pagination, root-event backfill, and unread badges.
src/app/features/room/RoomTimeline.tsx	Adopts `useMessageEdit` and passes `handleEdit` into timeline actions.
src/app/features/common-settings/developer-tools/DevelopTools.tsx	Adds thread diagnostics + “fetch from server” action for debugging thread state.
.changeset/feat-thread-enhancements.md	Declares a minor release note for thread support features.

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src/app/hooks/timeline/useTimelineEventRenderer.tsx

src/app/features/room/ThreadBrowser.tsx

src/app/features/room/ThreadDrawer.tsx

src/app/hooks/useMessageEdit.ts

- useTimelineEventRenderer.tsx: Use Math.max(thread.length, replyEvents.length) to avoid undercounting replies when only a subset of events is loaded locally. - ThreadBrowser.tsx: Use Math.max(thread.length, localReplyCount) to show correct total even for threads whose timeline hasn't been fully paginated. - ThreadDrawer.tsx: Align showClientUrlPreview logic with RoomTimeline: require both clientUrlPreview AND encClientUrlPreview in encrypted rooms. - useMessageEdit.ts: Minor wording: 'never stales' → 'never goes stale'.

…st-message

…ges, and UI fixes

…ngeset

Fired on every room message, causing N×chip re-renders and O(n_events) scans per message when N threads are visible. ThreadEvent.NewReply/Update and RoomEvent.Redaction already cover the relevant updates.

7w1 · 2026-03-31T00:46:46Z

Proper threads! Yay! only thing I noticed is some styling with scrollbars in the thread drawer:

7w1 · 2026-03-31T00:51:45Z

src/app/features/room/ThreadDrawer.tsx

+    !!threadObjForLoading && !threadObjForLoading.initialEventsFetched && replyEvents.length === 0;

-  replyEventsRef.current = replyEvents;
+  // Automatically paginate backwards until all older replies are loaded.


We probably shouldn't be paginating backwards until all replies are loaded? If its a huge thread with like 2000 replies we should just paginate when the user scrolls up, not automatically, unless I'm misunderstanding something

Just-Insane force-pushed the feat/thread-enhancements branch from 29282cb to 740e69c Compare March 28, 2026 02:33

Just-Insane changed the title ~~feat(threads): add full thread support with ThreadDrawer and ThreadBrowser~~ feat: add Matrix thread support Mar 28, 2026

Just-Insane marked this pull request as ready for review March 28, 2026 02:48

Just-Insane requested review from 7w1 and hazre as code owners March 28, 2026 02:48

Copilot AI review requested due to automatic review settings March 28, 2026 02:48

Copilot started reviewing on behalf of Just-Insane March 28, 2026 02:48 View session

Copilot AI reviewed Mar 28, 2026

View reviewed changes

Just-Insane changed the title ~~feat: add Matrix thread support~~ feat: Update Matrix threads Mar 28, 2026

Just-Insane force-pushed the feat/thread-enhancements branch 3 times, most recently from a0e4ef7 to b595e6b Compare March 29, 2026 18:31

Just-Insane added 4 commits March 30, 2026 08:48

feat(threads): enable threadSupport, fix drawer init, and add edit-la…

d37ac37

…st-message

feat(threads): server-side thread browser with pagination, unread bad…

95bc2e9

…ges, and UI fixes

feat(threads): update timeline hooks for thread rendering and add cha…

fde829d

…ngeset

perf: remove RoomEvent.UnreadNotifications from ThreadReplyChip

6709a58

Fired on every room message, causing N×chip re-renders and O(n_events) scans per message when N threads are visible. ThreadEvent.NewReply/Update and RoomEvent.Redaction already cover the relevant updates.

Just-Insane force-pushed the feat/thread-enhancements branch from d3520ef to 6709a58 Compare March 30, 2026 12:49

Just-Insane changed the title ~~feat: Update Matrix threads~~ feat(threads): thread drawer, thread browser, live reply counts, and unread badges Mar 30, 2026

fix(threads): close thread browser when jumping to thread root

33aaa5c

7w1 requested changes Mar 31, 2026

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feat(threads): thread drawer, thread browser, live reply counts, and unread badges#564

feat(threads): thread drawer, thread browser, live reply counts, and unread badges#564
Just-Insane wants to merge 5 commits intoSableClient:devfrom
Just-Insane:feat/thread-enhancements

Just-Insane commented Mar 28, 2026 •

edited

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7w1 commented Mar 31, 2026 •

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Just-Insane commented Mar 28, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Description

ThreadDrawer

ThreadBrowser

ThreadReplyChip (main timeline)

Thread button (RoomViewHeader)

Type of change

Checklist:

AI disclosure:

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Pull request overview

Reviewed changes

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7w1 commented Mar 31, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Just-Insane commented Mar 28, 2026 •

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7w1 commented Mar 31, 2026 •

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