[FEATURE] Add persistent session color setting

Related, perhaps a "session hook" could be used to set this up. That way, if I'm in a certain directory (e.g. a worktree), I could automatically set the color (and maybe /rename?) based on the worktree I'm using. Something similar to hooks could allow matchers or, for the original suggestion, just do it upon any session start.

Seeing lots of dupes of wanting a default color or to allow the assistant to alter the prompt color (me too!). #37749 has a more complete and helpful description of supporting a defaultColor _only_ customization.

However, a number of recently filed issues highlight a desire to persist a custom session _name_ as well as _color_ (e.g. across /clear commands) or to allow users to specify a default session name and color in settings*.json files. See #38649 and #39765 for examples.

A Notification start hook can set terminal colors based on project:

DIR=$(basename "$PWD")
case "$DIR" in
    *-prod*|*production*)  COLOR="\033[41m" ;; # Red bg for production
    *-staging*)            COLOR="\033[43m" ;; # Yellow for staging
    *-dev*|*develop*)      COLOR="\033[42m" ;; # Green for dev
    *)                     COLOR="\033[44m" ;; # Blue default
esac
tmux set -q status-style "bg=$(echo "$DIR" | md5sum | cut -c1-6)" 2>/dev/null
echo "Session color set for: $DIR" >&2
exit 0

Workaround: Automatic per-project terminal colors using hooks (macOS/Terminal.app)

I wanted different terminal colors depending on which project folder I launched Claude Code from, so I could visually distinguish sessions at a glance. Here's a hook-based solution that works today.

It's macOS/Terminal.app specific (uses AppleScript), but the pattern — SessionStart/SessionEnd hooks + a central config — is portable. You'd just swap the osascript lines for your terminal's equivalent.

Setup

1. Create a color config file (~/.claude/terminal-colors.conf):

# Format: path_pattern=bg_r,bg_g,bg_b|text_r,text_g,text_b
# RGB values are 0-65535 (Terminal.app scale)
# Pastel backgrounds with matching dark text
# Specific paths first (first match wins)

# Pastel salmon
my-projects/project-alpha=55000,35000,35000|8000,3000,3000
# Pastel sky blue
my-projects/project-beta=35000,50000,58000|3000,8000,12000
# Pastel mint
my-projects/project-gamma=35000,56000,53000|3000,10000,9000
# Pastel peach (root fallback)
my-projects=58000,45000,34000|12000,6000,2000

Add as many entries as you need. First match wins, so put specific subpaths before parent paths.

2. Create the start script (~/.claude/terminal-color-start.sh):

#!/bin/bash
CONF="$HOME/.claude/terminal-colors.conf"
SAVE_FILE="/tmp/claude-terminal-colors-${TERM_SESSION_ID:-default}"

# Save original colors
BG=$(osascript -e 'tell application "Terminal" to get background color of selected tab of front window' 2>/dev/null)
TEXT=$(osascript -e 'tell application "Terminal" to get normal text color of selected tab of front window' 2>/dev/null)
echo "$BG" > "$SAVE_FILE.bg"
echo "$TEXT" > "$SAVE_FILE.text"

# Find matching color from config (first match wins)
if [ -f "$CONF" ]; then
  while IFS='=' read -r pattern colors; do
    [[ "$pattern" =~ ^#.*$ || -z "$pattern" ]] && continue
    if [[ "$PWD" == *"$pattern"* ]]; then
      BG_COLOR="${colors%%|*}"
      TEXT_COLOR="${colors##*|}"
      osascript -e "tell application \"Terminal\" to set background color of selected tab of front window to {$BG_COLOR}"
      osascript -e "tell application \"Terminal\" to set normal text color of selected tab of front window to {$TEXT_COLOR}"
      break
    fi
  done < "$CONF"
fi

3. Create the end script (~/.claude/terminal-color-end.sh):

#!/bin/bash
SAVE_FILE="/tmp/claude-terminal-colors-${TERM_SESSION_ID:-default}"

if [ -f "$SAVE_FILE.bg" ] && [ -f "$SAVE_FILE.text" ]; then
  BG=$(cat "$SAVE_FILE.bg")
  TEXT=$(cat "$SAVE_FILE.text")
  osascript -e "tell application \"Terminal\" to set background color of selected tab of front window to {$BG}"
  osascript -e "tell application \"Terminal\" to set normal text color of selected tab of front window to {$TEXT}"
  rm -f "$SAVE_FILE.bg" "$SAVE_FILE.text"
fi

4. Make them executable:

chmod +x ~/.claude/terminal-color-start.sh ~/.claude/terminal-color-end.sh

5. Add hooks to your user-level settings (~/.claude/settings.json):

Add the following hooks key to your existing settings file. If you don't have one yet, create it with this content:

{
  "hooks": {
    "SessionStart": [
      {
        "matcher": "",
        "hooks": [
          {
            "type": "command",
            "command": "bash ~/.claude/terminal-color-start.sh"
          }
        ]
      }
    ],
    "SessionEnd": [
      {
        "matcher": "",
        "hooks": [
          {
            "type": "command",
            "command": "bash ~/.claude/terminal-color-end.sh"
          }
        ]
      }
    ]
  }
}

Note: If you already have a ~/.claude/settings.json with other settings, merge the "hooks" key into your existing file rather than replacing it.

How it works

• Hooks are defined once in user-level settings — they run for every session
• The start script checks $PWD against the config file and applies the matching color
• Original terminal colors are saved to a temp file (per tab via TERM_SESSION_ID) and restored on exit
• To add a new project, just add a line to terminal-colors.conf — no per-project settings needed
• Zero performance impact — just a couple of AppleScript calls on start/exit

Tips

• Use pastel backgrounds with matching dark text for comfortable long sessions
• Keep parent path entries (e.g., my-projects) below subpath entries so they act as fallbacks
• If $PWD doesn't match any entry, nothing changes — your terminal stays as-is

Limitations

• macOS Terminal.app only (uses AppleScript). Adaptable to iTerm2 (escape sequences) or Linux terminals (OSC sequences)
• Only changes background + text color, not the full ANSI palette

Would still love a native color setting in settings.json as proposed in this issue, but this works well in the meantime.