Group header and session list item overlaps buggily

[Giuspepe]

Description

1. Hovering on session list item of a session with sub-chats shows its chevron for collapsing/expanding the sub-chats above the group header
2. Hovering on group header renders it transparently causing the session list item below it to shine through

Issue Details

Item	Value
Issue Category	Bug
Target	Agents Window
VS Code Version	Code - Insiders 1.137.0-insider (023b880, 2026-09-08T00:36:40Z)
OS Version	Darwin arm64 25.6.0

System Info

Item	Value
VS Code Version	Code - Insiders 1.137.0-insider (023b880, 2026-09-08T00:36:40Z)
OS Version	Darwin arm64 25.6.0
CPUs	Apple M5 Max (18 x 2400)
GPU Status	2d_canvas: enabled GPU0: VENDOR= 0x106b [Google Inc. (Apple)], DEVICE=0x0000 [ANGLE (Apple, ANGLE Metal Renderer: Apple M5 Max, Version 26.6.2 (Build 25G83))], DRIVER_VENDOR=Apple, DRIVER_VERSION=26.6.2 ACTIVE Machine model name: Mac Machine model version: 17.6 direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: enabled_on trees_in_viz: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgpu: enabled webnn: disabled_off
Load (avg)	28, 32, 25
Memory (System)	128.00GB (33.58GB free)
Process Argv	--crash-reporter-id f3441869-abe8-416f-bbd5-01c71ecec52f
Screen Reader	no
VM	0%
User Agent	Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Code-Insiders/1.137.0-insider Chrome/148.0.7778.280 Electron/42.10.0 Safari/537.36
Installation pure	true

Attachments

[roblourens]