Control-Center/frontend/src/main.tsx

import { StrictMode } from 'react'
import { createRoot } from 'react-dom/client'
import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
import { BrowserRouter } from 'react-router-dom'
import ErrorBoundary from './components/ErrorBoundary'
import { ThemeProvider } from './hooks/useTheme'
import { SSEProvider } from './contexts/SSEContext'
import './index.css'
import App from './App'

const queryClient = new QueryClient({
  defaultOptions: {
    queries: {
      // No polling — real-time updates come through SSE.
      // staleTime is kept high; data is pushed, not pulled.
      staleTime: 60_000,
      refetchOnWindowFocus: false,
      retry: 1,
    },
  },
})

createRoot(document.getElementById('root')!).render(
  <StrictMode>
    <ErrorBoundary>
      <ThemeProvider>
        <QueryClientProvider client={queryClient}>
          {/* SSEProvider must live inside QueryClientProvider so it can call
              useQueryClient() to invalidate caches on incoming events. */}
          <SSEProvider>
            <BrowserRouter>
              <App />
            </BrowserRouter>
          </SSEProvider>
        </QueryClientProvider>
      </ThemeProvider>
    </ErrorBoundary>
  </StrictMode>,
)