Constant RX_BUSY_PREAMBLE_SYMBOLS 

pub const RX_BUSY_PREAMBLE_SYMBOLS: u16 = 32;

Preamble length, in symbols, assumed for a sender when sizing rx_busy_window_ms: the longest any current profile transmits (MeshCore’s 32 at SF7–SF8; it sends 16 at SF9–SF12). A device runner whose own TX preamble is longer assumes that instead.