Clean ovewview code

web/pages/Dashboard.tsx

@@ -1,7 +1,7 @@
 
 import React, { useState, useMemo, useRef, useEffect } from 'react';
 import { useNavigate } from 'react-router-dom';
-import { Phone, CheckCircle, Clock, UserCheck, Activity, Filter, ChevronDown, BarChart3, HelpCircle, Mail, Sparkles, ArrowDown, Bot, Zap, Rocket, LineChart, Layers, Fingerprint, Network, MonitorPlay, Plus } from 'lucide-react';
+import { Phone, CheckCircle, Clock, UserCheck, ChevronDown, BarChart3, HelpCircle, Mail, ArrowDown, Bot, Zap, Rocket, LineChart, Layers, Fingerprint, Network, MonitorPlay, Plus } from 'lucide-react';
 import { Card, Button } from '../components/UI';
 import { getDashboardStats } from '../services/mockData';
 import { Assistant } from '../types';
@@ -27,45 +27,78 @@ export const DashboardPage: React.FC = () => {
   }, [timeRange, selectedAssistantId]);
 
   useEffect(() => {
+    let disposed = false;
+
     const loadAssistants = async () => {
       try {
         const list = await fetchAssistants();
+        if (!disposed) {
           setAssistants(list);
+        }
       } catch (error) {
+        if (!disposed) {
           console.error(error);
         }
+      }
     };
+
     loadAssistants();
+
+    return () => {
+      disposed = true;
+    };
   }, []);
 
   useEffect(() => {
     const updateTopRailHeight = () => {
-      setTopRailHeight(topRailRef.current?.offsetHeight ?? 0);
+      const nextHeight = topRailRef.current?.offsetHeight ?? 0;
+      setTopRailHeight((prev) => (prev === nextHeight ? prev : nextHeight));
     };
 
     updateTopRailHeight();
 
-    const observer = new ResizeObserver(() => {
+    let observer: ResizeObserver | null = null;
+    if (typeof ResizeObserver !== 'undefined' && topRailRef.current) {
+      observer = new ResizeObserver(() => {
         updateTopRailHeight();
       });
-
-    if (topRailRef.current) {
       observer.observe(topRailRef.current);
     }
 
     window.addEventListener('resize', updateTopRailHeight);
     return () => {
+      if (observer) {
         observer.disconnect();
+      }
       window.removeEventListener('resize', updateTopRailHeight);
     };
   }, []);
 
   useEffect(() => {
     if (!scrollRootRef.current || !overviewRef.current) return;
+    if (typeof IntersectionObserver === 'undefined') {
+      const onScroll = () => {
+        if (!scrollRootRef.current || !overviewRef.current) return;
+        const rootRect = scrollRootRef.current.getBoundingClientRect();
+        const overviewRect = overviewRef.current.getBoundingClientRect();
+        const lowerBound = rootRect.top + rootRect.height * 0.35;
+        const upperBound = rootRect.bottom - rootRect.height * 0.35;
+        const isVisible = overviewRect.bottom > lowerBound && overviewRect.top < upperBound;
+        setIsOverviewVisible((prev) => (prev === isVisible ? prev : isVisible));
+      };
+
+      onScroll();
+      scrollRootRef.current.addEventListener('scroll', onScroll, { passive: true });
+      window.addEventListener('resize', onScroll);
+      return () => {
+        scrollRootRef.current?.removeEventListener('scroll', onScroll);
+        window.removeEventListener('resize', onScroll);
+      };
+    }
 
     const observer = new IntersectionObserver(
       ([entry]) => {
-        setIsOverviewVisible(entry.isIntersecting);
+        setIsOverviewVisible((prev) => (prev === entry.isIntersecting ? prev : entry.isIntersecting));
       },
       {
         root: scrollRootRef.current,
@@ -81,22 +114,25 @@ export const DashboardPage: React.FC = () => {
     const updateScrollRootCenter = () => {
       if (!scrollRootRef.current) return;
       const rect = scrollRootRef.current.getBoundingClientRect();
-      setScrollRootCenterX(rect.left + rect.width / 2);
+      const nextCenterX = rect.left + rect.width / 2;
+      setScrollRootCenterX((prev) => (prev === nextCenterX ? prev : nextCenterX));
     };
 
     updateScrollRootCenter();
 
-    const observer = new ResizeObserver(() => {
+    let observer: ResizeObserver | null = null;
+    if (typeof ResizeObserver !== 'undefined' && scrollRootRef.current) {
+      observer = new ResizeObserver(() => {
         updateScrollRootCenter();
       });
-
-    if (scrollRootRef.current) {
       observer.observe(scrollRootRef.current);
     }
 
     window.addEventListener('resize', updateScrollRootCenter);
     return () => {
+      if (observer) {
         observer.disconnect();
+      }
       window.removeEventListener('resize', updateScrollRootCenter);
     };
   }, []);