Claude code automatic dark/light mode theme switching

alacritty-theme-switcher.sh

#!/bin/bash

# Check if macOS is in dark mode
# Returns "Dark" if dark mode is on, nothing if light mode
DARK_MODE=$(defaults read -g AppleInterfaceStyle 2>/dev/null)

# Path to the active color config file
COLOR_FILE="$HOME/.config/alacritty/color.toml"

if [ "$DARK_MODE" = "Dark" ]; then
    # Copy dark theme
    cat > "$COLOR_FILE" << 'EOF'
# Active theme: Solarized Dark
[colors.primary]
background = "#002b36"
foreground = "#839496"

[colors.normal]
black = "#073642"
red = "#dc322f"
green = "#859900"
yellow = "#b58900"
blue = "#268bd2"
magenta = "#d33682"
cyan = "#2aa198"
white = "#eee8d5"

[colors.bright]
black = "#002b36"
red = "#cb4b16"
green = "#586e75"
yellow = "#657b83"
blue = "#839496"
magenta = "#6c71c4"
cyan = "#93a1a1"
white = "#fdf6e3"
EOF
    echo "Switched to dark theme"
    # Update tmux theme for dark mode
    tmux set-option -g status-style "fg=colour15,bg=colour0" 2>/dev/null || true
else
    # Copy light theme
    cat > "$COLOR_FILE" << 'EOF'
# Active theme: Solarized Light
[colors.primary]
background = "#fdf6e3"
foreground = "#657b83"

[colors.normal]
black = "#073642"
red = "#dc322f"
green = "#859900"
yellow = "#b58900"
blue = "#268bd2"
magenta = "#d33682"
cyan = "#2aa198"
white = "#eee8d5"

[colors.bright]
black = "#002b36"
red = "#cb4b16"
green = "#586e75"
yellow = "#657b83"
blue = "#839496"
magenta = "#6c71c4"
cyan = "#93a1a1"
white = "#fdf6e3"
EOF
    echo "Switched to light theme"
    # Update tmux theme for light mode
    tmux set-option -g status-style "fg=colour0,bg=colour7" 2>/dev/null || true
fi

# Touch the main config to trigger reload
touch "$HOME/.config/alacritty/alacritty.toml"

# include this in your alacrity.toml:
# [general]
# import = [
#  "~/.config/alacritty/color.toml"
# ]

com.dark-mode-theme-switcher.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.dark-mode-theme-switcher</string>
    <key>ProgramArguments</key>
    <array>
        <string>/Users/cgenco/.config/alacritty/theme-watcher.swift</string>
    </array>
    <key>KeepAlive</key>
    <true/>
    <key>RunAtLoad</key>
    <true/>
    <key>StandardErrorPath</key>
    <string>/tmp/dark-mode-theme-switcher.err</string>
    <key>StandardOutPath</key>
    <string>/tmp/dark-mode-theme-switcher.out</string>
</dict>
</plist>

theme-watcher.swift

#!/usr/bin/swift

import Foundation

let scriptPath = "/Users/cgenco/.config/alacritty/dark-mode-theme-switcher.sh"

// Run the script once on start
Process.launchedProcess(launchPath: "/bin/bash", arguments: [scriptPath])

// Listen for appearance changes
DistributedNotificationCenter.default.addObserver(
    forName: NSNotification.Name("AppleInterfaceThemeChangedNotification"),
    object: nil,
    queue: nil
) { _ in
    Process.launchedProcess(launchPath: "/bin/bash", arguments: [scriptPath])
}

// Keep the script running
RunLoop.main.run()

update-claude-theme.sh

#!/bin/bash

# Get the current macOS appearance
APPEARANCE=$(defaults read -g AppleInterfaceStyle 2>/dev/null)

CLAUDE_SETTINGS="$HOME/.claude/settings.json"

# Determine which theme to use
if [[ "$APPEARANCE" == "Dark" ]]; then
    CLAUDE_THEME="dark"
else
    # Light mode (or if AppleInterfaceStyle is not set)
    CLAUDE_THEME="light"
fi

# Update Claude Code theme
if [ -f "$CLAUDE_SETTINGS" ]; then
    # Use jq to update the theme
    if command -v jq &> /dev/null; then
        jq --arg theme "$CLAUDE_THEME" '. + {theme: $theme}' "$CLAUDE_SETTINGS" > "$CLAUDE_SETTINGS.tmp" && \
        mv "$CLAUDE_SETTINGS.tmp" "$CLAUDE_SETTINGS"
        echo "Claude Code switched to $CLAUDE_THEME mode"
    else
        echo "Error: jq is required but not installed. Install with: brew install jq"
        exit 1
    fi
else
    # Create settings file with theme if it doesn't exist
    echo "{\"theme\": \"$CLAUDE_THEME\"}" > "$CLAUDE_SETTINGS"
    echo "Created Claude settings with $CLAUDE_THEME mode"
fi