Static buffer, no malloc: ```c // REQ-C-MEM-02; TEST-C-05 static uint8_t rx_buf[128]; size_t uart_read_safe(uint8_t *out, size_t max_len) { size_t n = uart_read(rx_buf, sizeof(rx_buf)); if (n > max_len) n = max_len; memcpy(out, rx_buf, n); return n; } ```