I will review this PR as soon as possible

Thanks for the work here — the round-trip design and the backend-fingerprint guards look solid. My main concern is architectural: most of the new "generic" machinery is really NVFP4-specific knowledge that has leaked into the transport layer — _TRANSFERABLE_ATTR_NAMES is empty for every quant except modelopt_fp4, IPC_POSTPROCESS_RESHAPES_QUANTS is a one-entry allowlist, and _rebind_quant_state_after_import hardcodes ModelOptNvFp4FusedMoEMethod while duplicating the dispatcher.set_quant_config(...) tail of process_weights_after_loading (which, as the docstring admits, only e2e parity would catch on drift). This means every future quant method forces edits back into weight_cache, and the duplication is a double-write against the real post-process. Could we instead invert this into an optional interface on the quant method (e.g. ipc_transferable_attrs() / ipc_reshapes_weights() / ipc_rebind_after_import(layer)), so weight_cache just asks each quant_method what to do without knowing any "modelopt_fp4" string, each quant owns its own adaptation, and the rebind logic shares one implementation with process_weights_after_loading? Happy to do it as a fast follow if you'd rather land NVFP4 first, but I think it's worth agreeing on the direction before this pattern gets copied for the next quant method.

Could we instead invert this into an optional interface on the quant method (e.g. ipc_transferable_attrs() / ipc_reshapes_weights() / ipc_rebind_after_import(layer)), so weight_cache just asks each quant_method what to do without knowing any "modelopt_fp4" string, each quant owns its own adaptation, and the rebind logic shares one implementation with

Fully agree with this, the quant method should be responsible for maintaining the states transferring between daemon and client. Will revise it soon.

Updated and refactored.