If you call `delay(1000)` inside `loop()`, your ESP32 drops incoming WebSocket packets and freezes HTTP server tasks. Instead, pin sensor polling to Core 0 with `xTaskCreatePinnedToCore()` and let the network stack handle incoming requests on Core 1. Dual-core microcontrollers should be treated like concurrent systems!

1. Run DRC (Design Rule Check) with fab manufacturer constraints (minimum 6 mil trace/space). 2. Add decoupling capacitors (100nF) right next to IC power pins. 3. Make power traces at least 20-30 mil thick to avoid voltage drop. 4. Ensure ground plane has no isolated copper islands. Save this before your next JLCPCB order!