Add debug flag management system

- Default debug flags settable by query param or env variable
- Allows comma-separated list of debug flags
- Runtime modification (enable/disable/set) via console
- Support "all" flag for enabling/disabling everything

server/scripts/modules/utils/debug.mjs

@@ -0,0 +1,148 @@
+// Debug flag management system
+// Supports comma-separated debug flags or "all" for everything
+// URL parameter takes priority over OVERRIDES.DEBUG
+
+let debugFlags = null; // memoized parsed flags
+let runtimeFlags = null; // runtime modifications via debugEnable/debugDisable/debugSet
+
+/**
+ * Parse debug flags from URL parameter or environment variable
+ * @returns {Set<string>} Set of enabled debug flags
+ */
+const parseDebugFlags = () => {
+	if (debugFlags !== null) return debugFlags;
+
+	let debugString = '';
+
+	// Check URL parameter first
+	const urlParams = new URLSearchParams(window.location.search);
+	const urlDebug = urlParams.get('debug');
+
+	if (urlDebug) {
+		debugString = urlDebug;
+	} else {
+		// Fall back to OVERRIDES.DEBUG
+		debugString = (typeof OVERRIDES !== 'undefined' ? OVERRIDES?.DEBUG : '') || '';
+	}
+
+	// Parse comma-separated values into a Set
+	if (debugString.trim()) {
+		debugFlags = new Set(
+			debugString
+				.split(',')
+				.map((flag) => flag.trim().toLowerCase())
+				.filter((flag) => flag.length > 0),
+		);
+	} else {
+		debugFlags = new Set();
+	}
+
+	return debugFlags;
+};
+
+/**
+ * Get the current active debug flags (including runtime modifications)
+ * @returns {Set<string>} Set of currently active debug flags
+ */
+const getActiveFlags = () => {
+	if (runtimeFlags !== null) {
+		return runtimeFlags;
+	}
+	return parseDebugFlags();
+};
+
+/**
+ * Check if a debug flag is enabled
+ * @param {string} flag - The debug flag to check
+ * @returns {boolean} True if the flag is enabled
+ */
+const debugFlag = (flag) => {
+	const activeFlags = getActiveFlags();
+
+	// "all" enables everything
+	if (activeFlags.has('all')) {
+		return true;
+	}
+
+	// Check for specific flag
+	return activeFlags.has(flag.toLowerCase());
+};
+
+/**
+ * Enable one or more debug flags at runtime
+ * @param {...string} flags - Debug flags to enable
+ * @returns {string[]} Array of currently active debug flags after enabling
+ */
+const debugEnable = (...flags) => {
+	// Initialize runtime flags from current state if not already done
+	if (runtimeFlags === null) {
+		runtimeFlags = new Set(getActiveFlags());
+	}
+
+	// Add new flags
+	flags.forEach((flag) => {
+		runtimeFlags.add(flag.toLowerCase());
+	});
+
+	return debugList();
+};
+
+/**
+ * Disable one or more debug flags at runtime
+ * @param {...string} flags - Debug flags to disable
+ * @returns {string[]} Array of currently active debug flags after disabling
+ */
+const debugDisable = (...flags) => {
+	// Initialize runtime flags from current state if not already done
+	if (runtimeFlags === null) {
+		runtimeFlags = new Set(getActiveFlags());
+	}
+
+	flags.forEach((flag) => {
+		const lowerFlag = flag.toLowerCase();
+		if (lowerFlag === 'all') {
+			// Special case: disable all flags
+			runtimeFlags.clear();
+		} else {
+			runtimeFlags.delete(lowerFlag);
+		}
+	});
+
+	return debugList();
+};
+
+/**
+ * Set debug flags at runtime (overwrites existing flags)
+ * @param {...string} flags - Debug flags to set (replaces all current flags)
+ * @returns {string[]} Array of currently active debug flags after setting
+ */
+const debugSet = (...flags) => {
+	runtimeFlags = new Set(
+		flags.map((flag) => flag.toLowerCase()),
+	);
+
+	return debugList();
+};
+
+/**
+ * Get current debug flags for inspection
+ * @returns {string[]} Array of currently active debug flags
+ */
+const debugList = () => Array.from(getActiveFlags()).sort();
+
+// Make debug functions globally accessible in development for console use
+if (typeof window !== 'undefined') {
+	window.debugFlag = debugFlag;
+	window.debugEnable = debugEnable;
+	window.debugDisable = debugDisable;
+	window.debugSet = debugSet;
+	window.debugList = debugList;
+}
+
+export {
+	debugFlag,
+	debugEnable,
+	debugDisable,
+	debugSet,
+	debugList,
+};