Sketch how you'd structure a FreeRTOS app that processes UART data without losing bytes.

I'd use the deferred-interrupt pattern with a queue. Create a queue sized for the worst-case burst (xQueueCreate). The UART RX ISR does the minimum: read the data register and xQueueSendFromISR the byte into the queue, then portYIELD_FROM_ISR(woken) so that if a higher-priority consumer was unblocked, the scheduler switches to it on ISR exit. A dedicated worker task blocks on xQueueReceive(..., portMAX_DELAY), waking to process each byte, so it consumes no CPU while idle and wakes promptly when data arrives. Because the queue copies by value and buffers depth-many items, the fast ISR and slower task are decoupled and bytes aren't lost as long as the queue depth covers the burst and the worker keeps up on average. If the worker updates shared state (counters, a parser context shared with other tasks), it protects that with a mutex (xSemaphoreCreateMutex) held only briefly. I'd give the worker a higher priority than background/reporting tasks so received data is handled promptly, set the UART ISR priority at or below configMAX_SYSCALL_INTERRUPT_PRIORITY so its FromISR call is legal, and for very high rates escalate to DMA into a buffer with a half/full-transfer interrupt rather than per-byte interrupts. The structure is: ISR produces to queue → worker task consumes → mutex guards any shared state.