Preflight Checklist
What's Wrong?
When running Claude Code inside tmux, the logo and "Thinking" animation text appear dull/washed-out compared to running Claude Code directly in the terminal. All other colors in tmux work correctly, and Claude Code's own text output (syntax highlighting, markdown, etc.) appears fine - only the branding UI elements (logo, thinking animation) are affected.
What Should Happen?
Logo and "Thinking" animation should have the same vibrant colors inside tmux as when running directly in the terminal.
Error Messages/Logs
Steps to Reproduce
- Open iTerm2
- Run claude - observe vibrant logo colors
- Open tmux inside iTerm2
- Run claude - observe dull/muted logo and "Thinking" animation colors
Claude Model
None
Is this a regression?
Yes, this worked in a previous version
Last Working Version
No response
Claude Code Version
2.1.77 (Claude Code)
Platform
Anthropic API
Operating System
macOS
Terminal/Shell
iTerm2
Additional Information
Environment
- Claude Code version: 2.1.77
- OS: macOS (Darwin 25.3.0, Apple Silicon)
- Terminal: iTerm2
- tmux version: 3.6
- Shell: zsh
- Theme: dark
tmux config (relevant parts):
set -g default-terminal "tmux-256color"
set -ag terminal-overrides ",xterm-256color:Tc"
set -g mouse on
set -s extended-keys on
set -as terminal-features ',xterm-256color:extkeys'
What I've tried (none of these fixed the issue):
- Setting COLORTERM=truecolor via set-environment -g COLORTERM truecolor
- Setting FORCE_COLOR=3 environment variable
- Adding set -ag terminal-overrides ",tmux-256color:RGB"
- Setting set -g allow-passthrough all
- Setting set-environment -g TERM_PROGRAM iTerm.app
- Setting COLORFGBG="15;0" in shell
- Changing default-terminal to xterm-256color
- Setting theme to dark via /theme
Truecolor verification:
Truecolor works correctly inside tmux for all other applications. Running the following produces three distinct, vibrant orange blocks:
printf '\e[38;2;231;111;44m██████ truecolor\e[0m\n'
printf '\e[38;5;208m██████ 256-color\e[0m\n'
printf '\e[38;2;204;102;0m██████ truecolor darker\e[0m\n'
Suspected cause
Claude Code likely performs its own terminal capability detection for UI elements and falls back to a muted color palette when it detects tmux, regardless of actual truecolor support.
Preflight Checklist
What's Wrong?
When running Claude Code inside tmux, the logo and "Thinking" animation text appear dull/washed-out compared to running Claude Code directly in the terminal. All other colors in tmux work correctly, and Claude Code's own text output (syntax highlighting, markdown, etc.) appears fine - only the branding UI elements (logo, thinking animation) are affected.
What Should Happen?
Logo and "Thinking" animation should have the same vibrant colors inside tmux as when running directly in the terminal.
Error Messages/Logs
Steps to Reproduce
Claude Model
None
Is this a regression?
Yes, this worked in a previous version
Last Working Version
No response
Claude Code Version
2.1.77 (Claude Code)
Platform
Anthropic API
Operating System
macOS
Terminal/Shell
iTerm2
Additional Information
Environment
tmux config (relevant parts):
set -g default-terminal "tmux-256color"
set -ag terminal-overrides ",xterm-256color:Tc"
set -g mouse on
set -s extended-keys on
set -as terminal-features ',xterm-256color:extkeys'
What I've tried (none of these fixed the issue):
Truecolor verification:
Truecolor works correctly inside tmux for all other applications. Running the following produces three distinct, vibrant orange blocks:
printf '\e[38;2;231;111;44m██████ truecolor\e[0m\n'
printf '\e[38;5;208m██████ 256-color\e[0m\n'
printf '\e[38;2;204;102;0m██████ truecolor darker\e[0m\n'
Suspected cause
Claude Code likely performs its own terminal capability detection for UI elements and falls back to a muted color palette when it detects tmux, regardless of actual truecolor support.