How should an ESP32 telemetry queue behave while Wi-Fi is disconnected?

Choose the policy from the meaning of the data. A current temperature display may need only the newest valid reading, whereas an energy total or alarm transition needs different handling. Keep acquisition timestamps and sequence numbers so receivers can distinguish historical samples from live state.

Calculate the storage budget before selecting a queue depth. At 10 samples per second and 24 bytes per record, one hour needs 864,000 bytes before allocator, protocol or filesystem overhead. Define a maximum outage window and an explicit action when the buffer is full.

On reconnect, cap replay traffic so it does not starve current measurements or other radio work. Test duplicate delivery and reconnect loops, and make the receiver's processing idempotent where possible. If using flash, batch writes deliberately and evaluate wear, power-loss behavior and data recovery.