fix: prevent repeated menu activations

src/lib/actionActivation.ts

@@ -0,0 +1,42 @@
+export const DEFAULT_REPEATED_ACTIVATION_WINDOW_MS = 500;
+
+export interface ActionActivationGuard {
+  lastActivatedAt?: number;
+  running?: boolean;
+}
+
+function nowMs(): number {
+  if (typeof performance !== "undefined" && typeof performance.now === "function") {
+    return performance.now();
+  }
+  return Date.now();
+}
+
+export function shouldSuppressRepeatedActivation(
+  guard: ActionActivationGuard,
+  now = nowMs(),
+  windowMs = DEFAULT_REPEATED_ACTIVATION_WINDOW_MS,
+): boolean {
+  if (guard.lastActivatedAt !== undefined && now - guard.lastActivatedAt < windowMs) {
+    return true;
+  }
+  guard.lastActivatedAt = now;
+  return false;
+}
+
+export function suppressEvent(event: Event) {
+  event.preventDefault();
+  event.stopPropagation();
+  event.stopImmediatePropagation?.();
+}
+
+export function tryStartExclusiveActivation(guard: ActionActivationGuard): (() => void) | null {
+  if (guard.running) return null;
+  guard.running = true;
+  let finished = false;
+  return () => {
+    if (finished) return;
+    finished = true;
+    guard.running = false;
+  };
+}