Constant MAX_FRAME_PACKAGE_SIZE 

pub const MAX_FRAME_PACKAGE_SIZE: usize = _; // 12_582_912usize

API frame package limit.

C++ FTLogin channel rejects packages larger than kMaxPackageSize (FTLogin/Src/ftlogin/channel/impl/channel_impl.h:91, decoder.cpp:54-61), where package size includes the protocol header. Apply the same defensive upper bound before reserving memory for local FTAPI frames.