diff --git a/run-dev.sh b/run-dev.sh
new file mode 100755
index 0000000..8e1a213
--- /dev/null
+++ b/run-dev.sh
@@ -0,0 +1,365 @@
+#!/bin/bash
+# Run Chattyness servers in development mode
+set -eu
+
+cd "$(dirname "$0")"
+
+# =============================================================================
+# Constants
+# =============================================================================
+readonly APP_PORT=3000
+readonly OWNER_PORT=3001
+readonly LOCKFILE=".run-dev.lock"
+
+# Process IDs (set during runtime)
+OWNER_PID=""
+APP_PID=""
+
+# =============================================================================
+# Helper Functions
+# =============================================================================
+
+usage() {
+	cat <<EOF
+Usage: $0 [build|watch] [--user-app|--owner-app|--both] [-f|-k|-s|-r]
+
+Commands:
+  build   Build and run servers (default)
+  watch   Watch mode with hot reload
+
+Options:
+  --user-app    Run only the user app (port $APP_PORT)
+  --owner-app   Run only the owner admin (port $OWNER_PORT)
+  --both        Run both servers (default)
+  -f, --force   Kill existing instance and start new one
+  -k, --kill    Kill existing instance and exit
+  -s, --status  Check if an instance is running
+  -r, --release Build and run in release mode
+
+Examples:
+  $0                     # Build and run both
+  $0 watch               # Watch mode for both
+  $0 --owner-app         # Build and run owner only
+  $0 watch --user-app    # Watch mode for user app only
+  $0 -f watch            # Kill existing, then watch mode
+  $0 -k                  # Kill existing instance
+  $0 -s                  # Check status
+  $0 -r                  # Build and run in release mode
+EOF
+	exit 1
+}
+
+# Target helper functions
+run_owner() { [ "$TARGET" = "both" ] || [ "$TARGET" = "owner" ]; }
+run_app() { [ "$TARGET" = "both" ] || [ "$TARGET" = "app" ]; }
+
+# Cleanup function - kills child processes and removes lock file
+cleanup() {
+	echo ""
+	echo "Shutting down..."
+	[ -n "$OWNER_PID" ] && kill "$OWNER_PID" 2>/dev/null || true
+	[ -n "$APP_PID" ] && kill "$APP_PID" 2>/dev/null || true
+	[ -n "$OWNER_PID" ] && wait "$OWNER_PID" 2>/dev/null || true
+	[ -n "$APP_PID" ] && wait "$APP_PID" 2>/dev/null || true
+	rm -f "$LOCKFILE"
+	echo "Done."
+}
+
+# Print server URLs based on what's running
+print_server_info() {
+	local mode="$1"
+	local build_type="Debug"
+	[ "$RELEASE" = "true" ] && build_type="Release"
+	echo ""
+	echo "========================================"
+	echo "  Chattyness Development ($mode - $build_type)"
+	echo "========================================"
+	echo ""
+	if run_owner; then
+		echo "  Owner Admin: http://127.0.0.1:$OWNER_PORT"
+	fi
+	if run_app; then
+		echo "  User App:    http://127.0.0.1:$APP_PORT"
+		echo "  Realm Admin: http://127.0.0.1:$APP_PORT/admin"
+	fi
+	echo ""
+	if [ "$TARGET" = "both" ]; then
+		echo "Admin CSS lazy-loaded via symlink from owner build."
+	fi
+	echo "Press Ctrl+C to stop"
+	echo ""
+}
+
+# Wait for running child processes
+wait_for_processes() {
+	if [ "$TARGET" = "both" ]; then
+		wait "$OWNER_PID" "$APP_PID"
+	elif [ "$TARGET" = "owner" ]; then
+		wait "$OWNER_PID"
+	else
+		wait "$APP_PID"
+	fi
+}
+
+# Create symlink for admin CSS (user app loads admin CSS from owner build)
+setup_admin_css_symlink() {
+	mkdir -p apps/chattyness-app/public
+	local target="../../../target/site-owner/static/chattyness-owner.css"
+	local link="apps/chattyness-app/public/admin.css"
+	if [ ! -L "$link" ]; then
+		ln -sf "$target" "$link"
+		echo "Created symlink: $link -> $target"
+	fi
+}
+
+# Load environment variables from .env file
+load_env() {
+	if [ -f .env ]; then
+		set -a
+		# shellcheck source=/dev/null
+		source .env
+		set +a
+	fi
+}
+
+# Validate required environment variables
+check_env() {
+	if [ -z "${DB_CHATTYNESS_OWNER:-}" ]; then
+		echo "Error: DB_CHATTYNESS_OWNER not set"
+		echo "Create a .env file with DB_CHATTYNESS_OWNER=your_password"
+		exit 1
+	fi
+
+	if [ -z "${DB_CHATTYNESS_APP:-}" ]; then
+		echo "Error: DB_CHATTYNESS_APP not set"
+		echo "Create a .env file with DB_CHATTYNESS_APP=your_password"
+		exit 1
+	fi
+}
+
+# =============================================================================
+# Lock File Management
+# =============================================================================
+
+# Check if another instance is running (returns PID or empty)
+get_running_pid() {
+	if [ -f "$LOCKFILE" ]; then
+		local pid
+		pid=$(cat "$LOCKFILE" 2>/dev/null)
+		if [ -n "$pid" ] && kill -0 "$pid" 2>/dev/null; then
+			echo "$pid"
+		fi
+	fi
+}
+
+# Handle --status flag
+handle_status() {
+	local pid
+	pid=$(get_running_pid)
+	if [ -n "$pid" ]; then
+		echo "Running (PID: $pid)"
+		exit 0
+	else
+		echo "Not running"
+		[ -f "$LOCKFILE" ] && rm -f "$LOCKFILE" # Clean stale lock
+		exit 1
+	fi
+}
+
+# Kill any running instance (shared by -k and -f)
+kill_running_instance() {
+	local pid
+	pid=$(get_running_pid)
+	if [ -n "$pid" ]; then
+		echo "Killing existing run-dev.sh (PID: $pid)..."
+		kill "$pid"
+	else
+		echo "No running instance found."
+		[ -f "$LOCKFILE" ] && rm -f "$LOCKFILE" # Clean stale lock
+	fi
+	echo "Killing chattyness processes..."
+	killall -9 chattyness-app 2>/dev/null || true
+	killall -9 chattyness-owner 2>/dev/null || true
+	echo "Done."
+}
+
+# Handle --kill flag
+handle_kill() {
+	kill_running_instance
+	exit 0
+}
+
+# Handle --force flag (kill existing, then continue)
+handle_force() {
+	kill_running_instance
+	sleep 1 # Allow lock release
+}
+
+# Acquire exclusive lock
+acquire_lock() {
+	exec 200>"$LOCKFILE"
+	if ! flock -n 200; then
+		local pid
+		pid=$(cat "$LOCKFILE" 2>/dev/null)
+		echo ""
+		echo "ERROR: Another run-dev.sh instance is already running (PID: $pid)"
+		echo ""
+		echo "Options:"
+		echo "  $0 -k              Kill the existing instance"
+		echo "  $0 -f [args...]    Kill existing and start new instance"
+		echo "  $0 -s              Check status"
+		echo ""
+		exit 1
+	fi
+	echo $$ >"$LOCKFILE"
+}
+
+# =============================================================================
+# Main Commands
+# =============================================================================
+
+do_watch() {
+	echo "Starting watch mode..."
+	echo ""
+
+	local release_flag=""
+	[ "$RELEASE" = "true" ] && release_flag="--release"
+
+	# Build owner first to create CSS (needed if user app needs admin CSS)
+	if run_owner; then
+		echo "Building owner app first (for admin CSS)..."
+		cargo leptos build -p chattyness-owner $release_flag
+		setup_admin_css_symlink
+	fi
+
+	# Start watch processes
+	if run_owner; then
+		cargo leptos watch -p chattyness-owner $release_flag &
+		OWNER_PID=$!
+	fi
+
+	if run_app; then
+		cargo leptos watch -p chattyness-app --split $release_flag &
+		APP_PID=$!
+	fi
+
+	print_server_info "Watch Mode"
+	wait_for_processes
+}
+
+do_build() {
+	local release_flag=""
+	local target_dir="debug"
+	if [ "$RELEASE" = "true" ]; then
+		release_flag="--release"
+		target_dir="release"
+	fi
+
+	# Build phase
+	if run_owner; then
+		echo "Running: cargo leptos build -p chattyness-owner $release_flag"
+		cargo leptos build -p chattyness-owner $release_flag
+		setup_admin_css_symlink
+	fi
+
+	if run_app; then
+		echo ""
+		echo "Running: cargo leptos build -p chattyness-app --split $release_flag"
+		cargo leptos build -p chattyness-app --split $release_flag
+	fi
+
+	# Verify binaries exist
+	if run_owner && [ ! -x "./target/$target_dir/chattyness-owner" ]; then
+		echo "Error: ./target/$target_dir/chattyness-owner not found or not executable"
+		exit 1
+	fi
+	if run_app && [ ! -x "./target/$target_dir/chattyness-app" ]; then
+		echo "Error: ./target/$target_dir/chattyness-app not found or not executable"
+		exit 1
+	fi
+
+	# Start servers
+	if run_owner; then
+		echo "Starting Owner Server on :$OWNER_PORT..."
+		./target/$target_dir/chattyness-owner &
+		OWNER_PID=$!
+	fi
+
+	if run_app; then
+		echo "Starting App Server on :$APP_PORT..."
+		./target/$target_dir/chattyness-app &
+		APP_PID=$!
+	fi
+
+	print_server_info "Servers"
+	wait_for_processes
+}
+
+# =============================================================================
+# Main Entry Point
+# =============================================================================
+
+# Parse arguments
+LEPTOS_CMD="build"
+TARGET="both"
+FORCE="false"
+KILL_EXISTING="false"
+CHECK_STATUS="false"
+RELEASE="false"
+
+for arg in "$@"; do
+	case $arg in
+	build | watch)
+		LEPTOS_CMD="$arg"
+		;;
+	--user-app)
+		TARGET="app"
+		;;
+	--owner-app)
+		TARGET="owner"
+		;;
+	--both)
+		TARGET="both"
+		;;
+	-f | --force)
+		FORCE="true"
+		;;
+	-k | --kill)
+		KILL_EXISTING="true"
+		;;
+	-s | --status)
+		CHECK_STATUS="true"
+		;;
+	-r | --release)
+		RELEASE="true"
+		;;
+	--help | -h)
+		usage
+		;;
+	*)
+		echo "Unknown option: $arg"
+		usage
+		;;
+	esac
+done
+
+# Handle special flags first (before acquiring lock)
+[ "$CHECK_STATUS" = "true" ] && handle_status
+[ "$KILL_EXISTING" = "true" ] && handle_kill
+[ "$FORCE" = "true" ] && handle_force
+
+# Acquire lock and store PID
+acquire_lock
+
+# Set up cleanup trap
+trap cleanup EXIT INT TERM
+
+# Load and validate environment
+load_env
+check_env
+
+# Run the requested command
+case "$LEPTOS_CMD" in
+watch) do_watch ;;
+build) do_build ;;
+esac