[FEATURE] Add persistent defaultSessionColor setting

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

/color <name> sets the session color, but the setting is per-session only. There's no documented field in settings.json, no CLI flag (claude --help shows none), and no claude config subcommand to persist it.

Proposed Solution

Add a top-level setting, e.g.:

{
"defaultSessionColor": "cyan"
}

Accepted values would match the existing /color choices: red, blue, green, yellow, purple, orange, pink, cyan, default.

On session start, Claude Code would apply this color automatically. /color <name> would still override for the current session.

Alternative Solutions

• SessionStart hook — hooks output context to the model, not UI commands, so they can't invoke /color.
• Shell wrapper / alias — no CLI flag exists to pass color in.

Priority

Low - Nice to have

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

Why

• I prefer a specific color (cyan) across all my sessions for visual consistency.
• Typing /color cyan every session is friction, especially across many short-lived sessions / worktrees.
• Other per-session settings (model, effortLevel, theme, permissions.defaultMode) are already persistable in settings.json — this fits the same pattern.