Reopening request: tab color/visual differentiation for concurrent Claude Code sessions

Summary
When running multiple Claude Code sessions in parallel (e.g. one persistent session per project/persona), tabs are visually identical aside from the title text. There's no way to color-code, tag, or otherwise visually distinguish tabs at a glance.

Use case
I run several long-lived Claude Code sessions concurrently, one per project directory, each acting as a distinct persona on my team (e.g. one handles dev work, one handles infra, one handles content, etc.). I typically have 5+ tabs open simultaneously. Each session is started with a consistent <name>-resume naming convention, so the title text is already as distinct as I can make it, but at a glance, in a tab strip, all 5 tabs look the same: same icon, same layout, same color. I have to read the small title text on every tab to know which is which, every time I switch.

Request
Per-tab (or per-session/per-project) accent color or icon, so tabs are distinguishable by a quick glance rather than reading text. Ideally:

• User-assignable color per tab, OR
• Auto-derived color per project/working directory, consistent across sessions in that project, OR
• At minimum, a colored dot/bar tied to session name, similar to how browser tab groups work.

Related
Saw #55635 (accent color customization) was closed without implementation. Filing this with a more concrete multi-session use case in case it changes the calculus, this isn't cosmetic preference, it's a real workflow cost when managing several concurrent agent sessions.