Set iTerm2 tab colours based on the command you are running

.iterm-colours.zsh

# A dotfile to turn iTerm2 tabs a different colour based on the command glob.
# Useful for marking different environments in different colours.
# Cargo-culted from multiple sources, apologies for not fully acknowledging them :(

# Edit the line that reads "if [[ "$1" =~ "^(login-helper) " ]]; then" and replace
# "login-helper" with whatever command you use to authenticate. Then modify the case
# statement to match your auth command's arguments. For example: you may use a script
# called "authsaml" to authenticate, and its arguments are dev, test, preprd, and prd.

# Change the colour function you call if you want to change tab colours.

# This basic framework can also be used to execute environment setup functions too.
# For example: setting environment variables, copying files, etc etc.

# Save this as ~/.iterm-colours.zsh then call it from your .zshrc with:
# [[ -f ~/.iterm-colours.zsh ]] && source ~/.iterm-colours.zsh

# The colours you set are defined in a function that calls another pair of functions.
# Here I've used Solarized Dark, One Dark, and a Dichromatic-friendly palette,
# but of course you can use anything you like.
# To see colours automatically in VSCode, use the "Color Highlight" extension.

# Solarized colours https://gist.github.com/ninrod/b0f86d77ebadaccf7d9d4431dd8e2983
function tab_sol_yellow { set_iterm_title "$1"; tab_color 181 137 0; }      #b58900
function tab_sol_orange { set_iterm_title "$1"; tab_color 203 75 22; }      #cb4b16
function tab_sol_red { set_iterm_title "$1"; tab_color 220 50 47; }         #d30102
function tab_sol_magenta { set_iterm_title "$1"; tab_color 211 54 130; }    #d33682
function tab_sol_violet { set_iterm_title "$1"; tab_color 108 113 196; }    #6c71c4
function tab_sol_blue { set_iterm_title "$1"; tab_color 38 139 210; }       #268bd2
function tab_sol_cyan { set_iterm_title "$1"; tab_color 42 161 152; }       #2aa198
function tab_sol_green { set_iterm_title "$1"; tab_color 133 153 0; }       #859900

# One Dark colours, from https://github.com/joshdick/onedark.vim/blob/main/colors/onedark.vim
function tab_one_yellow { set_iterm_title "$1"; tab_color 229 192 123; }    #e5c07b
function tab_one_orange { set_iterm_title "$1"; tab_color 209 154 102; }    #d19a66
function tab_one_red { set_iterm_title "$1"; tab_color 224 108 117; }       #e06c75
function tab_one_magenta { set_iterm_title "$1"; tab_color 198 120 221; }   #c678dd
function tab_one_blue { set_iterm_title "$1"; tab_color 97 175 239; }       #61afef
function tab_one_cyan { set_iterm_title "$1"; tab_color 86 182 194; }       #56b6c2
function tab_one_green { set_iterm_title "$1"; tab_color 152 195 121; }     #98c379

# More colorblind-friendly, from https://github.com/romainl/vim-dichromatic
function tab_dichro_liblue { set_iterm_title "$1"; tab_color 136 204 238; } #88ccee
function tab_dichro_yellow { set_iterm_title "$1"; tab_color 221 204 119; } #ddcc77
function tab_dichro_cyan { set_iterm_title "$1"; tab_color 68 170 153; }    #44aa99
function tab_dichro_khaki { set_iterm_title "$1"; tab_color 153 153 51; }   #999933
function tab_dichro_lipink { set_iterm_title "$1"; tab_color 204 102 119; } #cc6677
function tab_dichro_purple { set_iterm_title "$1"; tab_color 170 68 153; }  #aa4499
function tab_dichro_dkblue { set_iterm_title "$1"; tab_color 51 34 136; }   #332288
function tab_dichro_green { set_iterm_title "$1"; tab_color 17 119 51; }    #117733
function tab_dichro_dkpink { set_iterm_title "$1"; tab_color 136 34 85; }   #882255

title_help0()
{
  echo "ERROR: No argument provided."
  echo "Usage:"
  echo "  `basename -- $0` \"title\" to provide a new Terminal title."
}

title_help2()
{
  echo "ERROR: Too many arguments provided."
  echo "Usage:"
  echo "  `basename -- $0` \"title\" to provide a new Terminal title."
}

function set_iterm_title() {
  if [ $# -eq 0 ]
  then
    title_help0;
  elif [ $# -eq 1 ]
  then
    echo -ne "\033]0;$1\007"
  elif [ $# -gt 1 ]
  then
    title_help2;
  fi
}
alias title='set_iterm_title'

function titlepwd() {
  set_iterm_title `pwd`
}

# If you have a different terminal application, then you will almost
# certainly need to use different escape codes
# https://iterm2.com/documentation-escape-codes.html
function tab_color() {
  echo -n -e "\033]6;1;bg;red;brightness;$1\a"
  echo -n -e "\033]6;1;bg;green;brightness;$2\a"
  echo -n -e "\033]6;1;bg;blue;brightness;$3\a"
}

# iTerm2 tab color commands
if [[ -n "$ITERM_SESSION_ID" ]]; then

  tab-reset() { echo -ne "\033]6;1;bg;*;default\a"; }

  function iterm2_tab_precmd() {
    # tab-reset
  }

  function iterm2_tab_preexec() {
    if [[ "$1" =~ "^(login-helper) " ]]; then

      # Here we are switching on the AWS profile argument given to our helper
      # functions.
      case $1 in
        (*prod*)
          tab_one_red
        ;;
        (*stage*)
          tab_one_orange
        ;;
        (*qa*)
          tab_one_yellow
        ;;
        (*dev*)
          tab_one_green
        ;;
        *)
          tab-reset
        ;;
      esac

    # Reset the tab if needed.
    else
      # tab-reset
    fi
  }

  # all of that work for the magic to happen in these next 3 lines:
  autoload -U add-zsh-hook
  add-zsh-hook precmd  iterm2_tab_precmd
  add-zsh-hook preexec iterm2_tab_preexec
fi

First a screenshot of the solarized colours:

Here's a screenshot of the one dark colours:

And here's one for the colourblind dichromatic colours:

(Font is Iosevka Term Light, prompt is powerlevel10k