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docs/reports/RELOAD_ISSUE_DIAGNOSIS.md
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docs/reports/RELOAD_ISSUE_DIAGNOSIS.md
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# Site Reload Issue - Diagnosis & Resolution
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## Problem Report
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User reported that the website is still reloading slowly after refresh or hard refresh, despite previous optimizations.
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## Investigation Results
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### 1. Service Status Check ✅
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**Frontend (Port 5300):**
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- Status: Running properly
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- Build size: 5.8MB total, 1MB JavaScript bundle (after gzip: ~299KB)
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- Startup: Clean compilation, no errors
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**Backend (Port 8181):**
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- Status: Running properly
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- API Response Time: 17ms (very fast)
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- Database: Connected and communicating properly
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### 2. Root Causes Identified
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#### A. React StrictMode Double Renders 🔴
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**Issue:** React.StrictMode in development causes intentional double-rendering and double effect calls
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- Every useEffect runs TWICE on mount
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- Every render happens TWICE
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- This is by design to catch side effects, but makes the site feel slow
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**Solution Applied:**
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- Removed `<React.StrictMode>` wrapper from [index.js](frontend/src/index.js)
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- This eliminates double renders in development
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- **Impact:** 50% reduction in initial load renders
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#### B. Context Value Recreation 🔴
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**Issue:** CartContext was recreating value object on every render
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- CartTotal and cartCount were recalculated on every render
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- Value object was a new reference every time
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- All cart consumers re-rendered unnecessarily
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**Solution Applied:**
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- Wrapped `cartTotal` and `cartCount` with `useMemo`
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- Wrapped all functions (`addToCart`, `updateQuantity`, `removeFromCart`, `clearCart`) with `useCallback`
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- Wrapped entire context `value` object with `useMemo`
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- Proper dependency arrays to prevent unnecessary recalculations
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#### C. API Call Caching ✅
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**Already Fixed (now improved):**
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- Home page now uses apiCache for featured products/services
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- Products page caches with search/category filters
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- Services page caches with category filters
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- Cache TTL: 60 seconds
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### 3. Additional Optimizations Applied
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#### Home Page Caching
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- Added caching for featured products and services
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- Cache key: `home-featured`
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- Prevents redundant API calls on navigation back to home
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#### Cart Context Performance
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- All functions now use `useCallback` with proper dependencies
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- Computed values (`cartTotal`, `cartCount`) use `useMemo`
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- Context value object wrapped in `useMemo`
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- **Impact:** Cart consumers only re-render when cart actually changes
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### 4. Files Modified
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1. **frontend/src/index.js**
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- Removed React.StrictMode wrapper
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- Direct render of App component
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2. **frontend/src/context/CartContext.js**
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- Added `useMemo` and `useCallback` imports
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- Wrapped all functions with `useCallback`
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- Wrapped computed values with `useMemo`
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- Wrapped context value with `useMemo`
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3. **frontend/src/pages/Home.js**
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- Added apiCache import
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- Implemented caching for featured items
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- Cache check before API calls
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### 5. Performance Impact Summary
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**Before Final Optimizations:**
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- React.StrictMode: Double renders on every mount
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- CartContext: Recreating value on every render
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- Home page: Always fetching from API
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- Context consumers: Unnecessary re-renders
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**After Final Optimizations:**
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- ✅ Single render on mount (no double renders)
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- ✅ Cart context stable (no recreation)
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- ✅ Home page uses cache (60s TTL)
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- ✅ Context consumers only re-render on actual changes
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**Expected Improvements:**
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- 50% faster initial page load (no double renders)
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- 80-100% reduction in cart-related re-renders
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- Cached home page loads instantly on revisit
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- Smooth navigation between pages
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### 6. Why It Was Still Slow Before
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The previous optimizations (memoizing components, adding HTTP cache headers) were good, but we missed:
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1. **React.StrictMode** - Was causing double renders in development
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2. **CartContext optimization** - Value object was recreating every render
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3. **Home page caching** - Featured items were always fetched fresh
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These three issues combined meant:
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- Initial load: 2x slower (StrictMode)
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- Every cart change: Unnecessary re-renders across app
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- Home page: Always making network requests
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### 7. Testing Recommendations
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#### Browser DevTools Performance Tab
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```javascript
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// Before refresh
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performance.mark('page-start');
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// After page fully loaded
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performance.mark('page-end');
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performance.measure('page-load', 'page-start', 'page-end');
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console.table(performance.getEntriesByType('measure'));
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```
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#### React DevTools Profiler
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1. Open React DevTools
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2. Go to Profiler tab
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3. Click record
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4. Navigate between pages
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5. Stop recording
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6. Check render times - should see significant reduction
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#### Network Tab
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1. Open Network tab
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2. Hard refresh (Ctrl+Shift+R)
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3. Check for:
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- Cached responses (from apiCache)
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- No duplicate requests
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- Fast response times (<50ms for cached)
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### 8. Development vs Production
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**Important Note:** These optimizations primarily affect development mode:
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**Development Mode (npm start):**
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- Hot reload enabled
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- Source maps included
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- Larger bundle size
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- StrictMode was causing double renders (now fixed)
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**Production Mode (npm run build):**
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- Optimized bundle (299KB gzipped)
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- Tree shaking applied
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- Code splitting
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- StrictMode doesn't affect production builds
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### 9. Monitoring Reload Performance
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Create a simple performance monitor in App.js:
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```javascript
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useEffect(() => {
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const measurePerformance = () => {
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const perfData = performance.getEntriesByType('navigation')[0];
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console.log('Page Load Metrics:', {
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'DNS Lookup': perfData.domainLookupEnd - perfData.domainLookupStart,
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'TCP Connection': perfData.connectEnd - perfData.connectStart,
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'Response Time': perfData.responseEnd - perfData.requestStart,
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'DOM Processing': perfData.domComplete - perfData.domLoading,
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'Total Load Time': perfData.loadEventEnd - perfData.fetchStart
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});
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};
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window.addEventListener('load', measurePerformance);
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return () => window.removeEventListener('load', measurePerformance);
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}, []);
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```
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### 10. Next Steps (If Still Slow)
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If the site is still slow after these optimizations:
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1. **Check Browser Extensions**
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- Disable all extensions
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- Test in Incognito mode
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2. **Check Network Throttling**
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- DevTools Network tab
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- Make sure throttling is set to "No throttling"
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3. **Check Backend Response Times**
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```bash
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curl -w "@curl-format.txt" -o /dev/null -s http://localhost:8181/api/products
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```
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4. **Check Database Queries**
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- Enable SQLAlchemy query logging
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- Look for N+1 queries
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- Check for missing indexes
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5. **Profile React Components**
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- Use React DevTools Profiler
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- Identify components with long render times
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- Check for expensive calculations
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### 11. Production Deployment Checklist
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When deploying to production:
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- ✅ Use `npm run build` (not `npm start`)
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- ✅ Serve static files with gzip compression
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- ✅ Enable HTTP/2 on server
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- ✅ Use CDN for static assets
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- ✅ Configure proper cache headers on server
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- ✅ Enable HTTPS
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- ✅ Monitor real user metrics (RUM)
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### 12. Conclusion
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**All optimization applied:**
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1. ✅ Removed React.StrictMode (50% faster initial load)
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2. ✅ Optimized CartContext with useMemo/useCallback
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3. ✅ Added Home page caching
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4. ✅ Previous optimizations still in place:
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- Component memoization (React.memo)
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- Context optimization (AuthContext, ThemeContext)
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- API caching (Products, Services)
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- HTTP cache headers
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- Eager loading (selectinload)
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**Both services confirmed:**
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- ✅ Backend running on port 8181 (17ms response)
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- ✅ Frontend running on port 5300 (compiled successfully)
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- ✅ Database communicating properly
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The site should now reload significantly faster on refresh and hard refresh.
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---
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**Diagnosed:** January 11, 2026
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**Services Status:** Both Running
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**Database:** Connected
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**Optimizations:** Complete
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