[Bug]: Desktop chat timeline overlaps: mid-turn user message and "Working for…" pill render on top of a streaming tool-call group (regression of #1035)

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/desktop (Linux AppImage) — likely apps/web timeline rendering

Steps to reproduce

I have no idea, probably doing a mid turn bubble + expanding tool call group simultaeously

Expected behavior

Each timeline row reserves its own height. The tool-call group, the mid-turn user message, and the "Working for …" / "Running ssh" status line should stack vertically without overlapping.

Actual behavior

Rows are drawn on top of each other:

• The mid-turn user bubble ("ca7d62b5 is not snake right?") renders directly over the tool-call command rows.
• The "Working for 3m 46s" text and the "Running ssh" status line render on top of individual command lines inside the "Ran 10 commands" group, making both unreadable.
• The earlier user message above the group is positioned fine; only content at/after the still-growing tool-call group is affected.

Same symptom as #1035 (closed as fixed by #1953 in April), so this appears to be a regression of that on desktop. The currently open mobile reports #10846, #11119 and #11992 describe the same overlap behaviour on iOS/Android.

Impact

Cosmetic issue

Version or commit

T3 Code 0.0.41-nightly.20260915.1766 (AppImage: T3-Code-0.0.41-nightly.20260915.1766-x86_64.AppImage)

Environment

Fedora 44, kernel 7.0.10-200.fc44.x86_64, Wayland session. Provider: Claude Code (Claude Opus 5, High · 200k, Full access). Local checkout environment.

Screenshot

Workaround

Hiding and unhiding the tool call group fixes this

Start by tracing the chat timeline rendering in apps/desktop and the likely related components under apps/web, then compare the behavior with the fix from #1953 and the related mobile reports. Done means the tool-call group, mid-turn user message, and Working for… or Running ssh status rows reserve separate heights and remain readable while streaming.