Reported by Jay with a screenshot, 2026-07-26 (taOS on the Pi, desktop window, Messages open on the Mary DM).
Symptom
The conversation header block renders twice, stacked. Each copy shows the full row: the @ type icon, agent emoji, channel name ("Mary"), the ? guide link, the pin/search actions, a member count (2), and the "Direct messages with Mary" description line beneath. Below the doubled block the pane is otherwise normal ("No messages yet. Say hello to @Mary.").
Investigation so far (three hypotheses RULED OUT)
I could not reproduce this headlessly (no browser available), so this is code and data analysis only. Recording the dead ends so nobody repeats them:
1. Not an isMobile disagreement. First theory: MessagesApp and MobileSplitView compute "mobile" independently, so they could disagree and render MobileSplitView's nav bar (detailTitle) alongside the in-pane header. Disproved: useIsMobile (src/hooks/use-is-mobile.ts) and the local hook inside MobileSplitView.tsx are identical logic on the same 768 breakpoint, both driven by the viewport media query, so they cannot disagree. Also MobileSplitView returns early on desktop (around line 66) and ignores detailTitle entirely, so the desktop path renders no nav title at all.
2. Not duplicate DM channels. Checked the live channel list: exactly one DM channel for Mary (ebafc8ec4bd4) and one for Naira (379bdca85328). No duplicates. Unrelated observation worth its own look: there are 9 channels all named a2a, a separate naming collision.
3. Not a double render of the message area. messageAreaUI is constructed once (MessagesApp.tsx:1613) and passed once as the detail prop (line 2048). It appears nowhere else in the tree.
Where to look next
The in-pane header block is in MessagesApp.tsx around line 1642 (comment: "channel header — MobileSplitView owns back nav on mobile"). Since it is written once and its container renders once, the duplication most likely comes from either:
- an ancestor rendering the whole detail subtree twice (check whether the Messages window mounts two instances, e.g. the multi-window support, or a StrictMode double-mount leaving real DOM rather than being a dev-only artifact), or
- a stale cached bundle, showing a mix of old and new markup.
First thing to try when reproducing: hard-refresh to rule out a stale cached shell, then check whether the app is mounted twice (React DevTools, or count [data-testid=mobile-split-view] nodes in the DOM). If there are two split-view nodes, the bug is at the mount/window level and not in the header code at all.
Related
The "Mobile Messages polish" task already carries a "trim duplicate header" item, so a mobile variant of this was seen before. That one was addressed by suppressing detailTitle on mobile (MessagesApp.tsx:2045). This report is the desktop case, which that fix explicitly does not cover (the comment there says "Desktop keeps it").
Reported by Jay with a screenshot, 2026-07-26 (taOS on the Pi, desktop window, Messages open on the Mary DM).
Symptom
The conversation header block renders twice, stacked. Each copy shows the full row: the
@type icon, agent emoji, channel name ("Mary"), the?guide link, the pin/search actions, a member count (2), and the "Direct messages with Mary" description line beneath. Below the doubled block the pane is otherwise normal ("No messages yet. Say hello to @Mary.").Investigation so far (three hypotheses RULED OUT)
I could not reproduce this headlessly (no browser available), so this is code and data analysis only. Recording the dead ends so nobody repeats them:
1. Not an
isMobiledisagreement. First theory:MessagesAppandMobileSplitViewcompute "mobile" independently, so they could disagree and renderMobileSplitView's nav bar (detailTitle) alongside the in-pane header. Disproved:useIsMobile(src/hooks/use-is-mobile.ts) and the local hook insideMobileSplitView.tsxare identical logic on the same 768 breakpoint, both driven by the viewport media query, so they cannot disagree. AlsoMobileSplitViewreturns early on desktop (around line 66) and ignoresdetailTitleentirely, so the desktop path renders no nav title at all.2. Not duplicate DM channels. Checked the live channel list: exactly one DM channel for Mary (
ebafc8ec4bd4) and one for Naira (379bdca85328). No duplicates. Unrelated observation worth its own look: there are 9 channels all nameda2a, a separate naming collision.3. Not a double render of the message area.
messageAreaUIis constructed once (MessagesApp.tsx:1613) and passed once as thedetailprop (line 2048). It appears nowhere else in the tree.Where to look next
The in-pane header block is in
MessagesApp.tsxaround line 1642 (comment: "channel header — MobileSplitView owns back nav on mobile"). Since it is written once and its container renders once, the duplication most likely comes from either:First thing to try when reproducing: hard-refresh to rule out a stale cached shell, then check whether the app is mounted twice (React DevTools, or count
[data-testid=mobile-split-view]nodes in the DOM). If there are two split-view nodes, the bug is at the mount/window level and not in the header code at all.Related
The "Mobile Messages polish" task already carries a "trim duplicate header" item, so a mobile variant of this was seen before. That one was addressed by suppressing
detailTitleon mobile (MessagesApp.tsx:2045). This report is the desktop case, which that fix explicitly does not cover (the comment there says "Desktop keeps it").