[FEATURE] Color-code sessions by project/brand in the desktop app sidebar

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

I run many Claude Code sessions in parallel across different clients and brands. Right now I have 60+ sessions over about 30 project folders. In the desktop app's Code tab sidebar every session looks the same: plain text, no color, no label. Finding the right session takes real effort, especially in the date view where sessions from different projects are mixed together.

Titles alone don't solve this. The app writes them from the conversation, so two sessions from different clients can have similar titles ("Landing page", "Instagram posts"), and there's no quick visual cue for which client or project a session belongs to.

Proposed Solution

• A color for each session, shown as a colored dot or stripe next to the title in the sidebar. It could also show on the session tab and the prompt bar.
• A way to set one color for a whole project folder, so every new session in that folder gets it automatically.
• A quick way to change it: right-click a session or a sidebar group and pick "Set color".
• Colors on custom sidebar groups too, not only on sessions.
• A sessionColor output field that hooks and plugins can set, like the existing sessionTitle field in SessionStart / UserPromptSubmit hooks, so teams can script it.

Alternative Solutions

I built a small plugin as a workaround. Its SessionStart and UserPromptSubmit hooks return sessionTitle to put a colored emoji (🟢 🟤 🔵 …) in front of each session title, based on a map from folder to color. It works, but it has real limits:

• It changes the titles themselves, so the color is part of the name.
• The color can't appear until the second message, because the app only names a session after the first exchange.
• The choice is limited to the handful of colored emoji that exist, so large setups start to repeat colors.
• There's no way to color sidebar groups.

Custom sidebar groups help a little, but they only work when the sidebar is grouped by "custom", and they don't show at a glance in other views.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

I'm a designer at an agency and work on several client brands at once, each in its own folder (e.g. Clients/BrandA, Clients/BrandB, Games/, web_app/). On a typical day I switch between 5–10 active sessions.

With per-project colors I'd set Brand A = green, Brand B = brown, games = purple once. Every new session in those folders would pick up its color automatically, and I could jump to the right session in the sidebar without reading every title.

Additional Context

_No response_