Eager Session

The eager session API is split by responsibility:

• State holds the tapes, side tables, and reference generation.
• Parameters synchronizes host values and persistent CUDA mirrors.
• References validates handles and stores non-differentiable inputs.
• Lifecycle creates sessions and releases tape-owned buffers.
• Recording records leaves and reads tensor values.
• Backend binds accepted capsules to executable handlers.
• Random shares a deterministic key schedule across CPU and CUDA.

Import a leaf module when only one of these is needed. This facade preserves the full eager API.