[FEATURE] /rename --color: auto-assign unique session color on rename

Preflight Checklist

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

Problem Statement

When running 3-4 concurrent Claude Code sessions in tmux panes, I have to manually /rename each session AND separately /color each one to visually distinguish them. There's no way to know which colors are already in use by other sessions, so I often end up with duplicate colors or forget to set one entirely.

The core pain point: two separate manual steps for every session, with no coordination between them.

Proposed Solution

Add a --color flag to /rename:

/rename feature-auth --color auto    # hash name → deterministic unique color
/rename feature-auth --color blue    # set both name + color in one command

When --color auto is used, derive the color from the session name (e.g. simple hash mod over available colors). This guarantees the same name always gets the same color, and different names are likely to get different colors.

Bonus: expose the current session color in /statusline JSON data so custom status bars can reflect it.

Priority

Medium

Feature Category

CLI commands

Alternative Solutions

• A hook event like SessionRename that could trigger /color automatically — but this event doesn't exist today.
• Auto-assign a unique color on session creation (cycling through available colors), independent of /rename.

Use Case Example

# Terminal 1
/rename api-server --color auto     → gets "blue"

# Terminal 2  
/rename frontend --color auto       → gets "green"

# Terminal 3
/rename database-migration --color auto  → gets "purple"

Each tmux pane is now instantly distinguishable at a glance by both name and color.