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[Bug]: chat and composer shift far left when the thread details card is open on smaller screens #25834
Description
Area
apps/web
Steps to reproduce
- Use a window where the chat canvas is roughly 1012 to 1708 CSS px wide. A 13" MacBook Air with the sidebar open works, at about 1360px.
- Open a thread, or the new-thread screen, with the thread details card (top-right panel) open inline.
- Compare where the composer sits with the card open and with it closed.
Expected behavior
As before #25778: with the card inline, the chat stays centered in the canvas and moves only as far as it needs to clear the card plus DETAILS_CARD_CLEARANCE. At about 1360px that is roughly 28px.
Actual behavior
The chat and composer move up to 146px left so they center in the space beside the card. On a MacBook Air they sit noticeably left of center whenever the card is open. They only center again once both the sidebar and the card are closed. Opening or closing the card makes the whole chat column jump sideways.
Cause
#25778 ("the new design is the only design") removed the centerBesideDetails flag and enabled besideShift in apps/web/src/components/chat/chatCanvasLayout.ts (resolveChatCanvasLayout) for everyone. besideShift is max(0, 854 - W/2), capped at 146px. So any canvas narrower than about 1708px gets a large shift, even when the centered chat already clears the card (W >= ~1416px). Before #25778, the default path only clamped normalLeft to laneRight - normalWidth.
Impact
Cosmetic issue
Version or commit
main @ bc8d02f
Environment
macOS, T3 Code desktop, 13" MacBook Air
Activity
koushikxd commentedon Oct 27, 2026
Screenshots from a 13" MacBook Air with the sidebar open. They show the same new-thread screen with the details card open and closed:
Why this matters to me: I keep the sidebar and the details card open most of the time, and on the Air's screen this means the composer and the whole chat column are never centered. Every time I toggle the card, the chat jumps sideways, so the place I'm typing and reading moves under me. On a bigger display the card fits beside the chat, so it isn't noticeable there. On smaller laptop screens it's there all the time. Before the redesign, the card sat beside the chat without pushing it around, and that felt much calmer.
I opened #25838 to fix this. It restores the pre-#25778 placement, so the chat stays centered and only moves left as far as it needs to clear the card (85px instead of 146px on the Air with the sidebar open; screenshot in the PR).
fix(web): chat stays centered while the thread details card fits besi…