Desktop app: per-chat or per-group background colour so the chat pane shows which project it belongs to

Feature request

Let the user set a background colour (or shade) for an individual Claude Code chat, or for a sidebar group, so the chat pane itself shows which project or category the chat belongs to.

Why

I run many Claude Code chats at once in the desktop app, grouped by project (a website build, a data tool, home infrastructure, personal). With ten or more open, every chat pane looks identical, and it is easy to type into the wrong one. The sidebar group name is small and out of the eye line when you are reading a long transcript.

A colour on the chat background, even a faint tint, would tell me at a glance which project I am in. Assigning a colour per sidebar group would do most of the work; a per-chat override would cover the odd one out.

What it might look like

• A colour or shade picker on the session (right-click or the session menu), and on the sidebar group.
• The chosen colour applied as a subtle background tint to that chat's message area, and as a stripe or dot on its tab and sidebar row.
• A small palette of muted colours that keep the text readable in light and dark themes, rather than a free colour picker.

Related

#80776 asks for colour-coding in the sidebar. This request is for the chat pane itself, so the colour is visible while you are working in the chat, not only when you are switching between them.