## QA PASSED See QA report document: ef63b1bf-b62d-40dc-aa09-0d9f974464c5 **Verification Summary:** - Monitored page for 20 seconds (4 poll cycles) - Status indicator stayed stable as 'Connected' throughout - NO 'Checking...' flicker detected during background polling - Refresh icon animation observed during API calls - Manual refresh button works correctly - Power readings update smoothly without flickering - Mobile responsive layout verified - No console errors All hypotheses tested. Fix verified working as intended.

Fixed the header flickering issue by separating polling from manual refresh: **Changes made to `frontend/src/components/layout/header.tsx`:** 1. Added new state variables: - `isRefreshing` - tracks when any API call is in progress (for spinning refresh icon) - `isInitialLoad` - tracks if this is the first load (to show 'Checking...' only initially) 2. Split the connection check into two functions: - `pollConnection()` - for background 5-second polling; only updates `isRefreshing` state, does NOT change status to 'checking' - `checkConnection()` - for initial load and manual refresh button; shows 'checking' status only on initial load 3. Updated refresh button to use `isRefreshing` state instead of `status === 'checking'`: - Button is disabled while `isRefreshing` is true - Refresh icon spins when `isRefreshing` is true **Result:** - Initial page load shows 'Checking...' as expected - Background polling every 5 seconds only spins the refresh icon - Status indicator stays stable as 'Connected' or 'Disconnected' during polling - Power readings (voltage, current, power with progress bars) only update when new data arrives - Manual refresh button click works as before (does not show 'Checking...' since isInitialLoad is false after first load) **Verification:** - All 111 tests pass - Frontend builds successfully