[Bug]: Last user message setting does not sort the flat chat sidebar (0.1.2) #24884

Area

apps/web / shared sidebar ordering; the original observation was in the narrow flat Threads sidebar. The exact client platform/version was not independently verified.

Version or commit

Connected T3 server: 0.1.2, Linux x64. Observed on October 25, 2026. The sorting behavior described below was also checked in the web client bundle distributed with that server version.

Problem

I have several chats running and selected Last user message in settings expecting the chat I most recently messaged to move to the top. Sending a follow-up to an older chat leaves it below chats whose last user messages were hours earlier.

The available setting appears to be Project order, which controls the project picker and command palette rather than the flat Threads list. There is no corresponding last-user-message sort option exposed for that list. It is easy to believe the selected setting controls the visible sidebar, then conclude that sorting is broken.

Steps to reproduce

1. Have several active, unpinned chats, including an older chat and chats created more recently.
2. Set Settings → Project order → Last user message.
3. Open the flat Threads sidebar.
4. Send a new user message to the older chat.
5. Observe its position relative to chats whose last user messages are hours old.

Expected behavior

There should be a discoverable way to sort the flat chat list by last user message, newest first. When selected, sending a message to an older chat should move it above chats with older user messages. Agent replies should not keep reshuffling the list.

If Project order is intentionally limited to projects, its scope should be clear where users choose it, with a separate chat ordering control for the flat list. This report does not assume that the default ordering must change.

Actual behavior

The older chat stays farther down the list after a new user message, and the available Last user message setting does not change this.

In the observed example, the older chat's latest user message was recorded at 13:28 UTC on October 25, while another chat above it had its latest user message at 00:00 UTC that day. A read-only check confirmed the newer message was persisted, so this was not a missing message timestamp.

Investigation

In the installed 0.1.2 web bundle:

• The Project order setting describes its scope as the sidebar project picker and command palette.
• The flat active-thread list uses a separate ordering path. With the Working section disabled, it sorts by saved active order keys, falling back to creation/unsettled timestamps rather than latest user-message timestamps.
• The last-user-message sorter used by project thread lists is not applied to that flat active-thread path.

These observations describe the installed bundle; I have not reproduced this against the latest development branch or independently tested native mobile clients.

Impact

With many parallel chats, the conversation I am actively using remains buried below older activity. I have to search or scan the sidebar again immediately after messaging it. The similarly named setting makes it hard to tell whether this is a configuration mistake or an unsupported behavior.

Workaround

Pinning or manually reordering chats can keep them accessible, but does not provide automatic last-user-message ordering.

Related reports

• [Bug]: Web inbox thread list stays in creation order; activity never re-sorts it #16412 describes the same flat-list ordering problem and is currently closed. This is a follow-up documenting the behavior still observed with a 0.1.2 server/client bundle, not a claim that a particular merged fix regressed.
• Discussion [Feature]: Allow Sidebar V2 threads to be sorted by recent activity #6964 tracks optional recent-message ordering for Sidebar V2.
• PR feat(clients): add last-message sorting for active threads #22032 proposes an opt-in last-message order.

The main user-facing issue here is that selecting Last user message does not produce the expected ordering in the visible flat chat sidebar, and no equivalent chat sorting setting is available there.