Feature: custom border/frame color in settings.json

What

Allow users to set a custom color for the TUI border lines and session name banner via settings.json.

Why

Currently the border/frame and session name banner are hardcoded to cyan. But when using agent teams (CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1), each split pane gets a distinct auto-assigned color — so the rendering infra already supports multiple border colors.

Users who run multiple sessions (or rename sessions frequently) would benefit from visual distinction at a glance.

Proposed

A config key in settings.json, something like:

{
  "theme": {
    "borderColor": "purple"
  }
}

Or even better, let /rename accept a color:

/rename sentry --color purple

Environment

• Claude Code CLI on Linux (iTerm over SSH)
• Using custom statusLine command — that part works great
• The missing piece is the chrome around the input area

🤖 Generated with Claude Code