nx_session.nx

nx_session.nx -- composite substrate session for parallel-companion scenes. Bundles the five core runtime primitives every parallel-companion scene needs into one constructor: - NxActorScheduler actor lifecycle + cooperative scheduling - NxMessageBus typed inter-actor mailboxes + pub/sub - NxStreamMultiplexer priority-ordered output stream interleave - NxResourceArbiter VRAM / RAM / CPU budget arbitration - NxInterruptBroker sub-50ms preemption for operator inputs Replaces the ~30 lines of wiring boilerplate that nx_companion_compose, nx_dual_companion_compose, nx_triple_companion_compose, and nx_quad_companion_compose each currently duplicate. One call -> entire substrate ready: let s: *NxSession = nx_session_new( n_actors_capacity, mailbox_capacity, mux_capacity, arb_capacity, broker_capacity, starvation_threshold_us, quantum_per_actor, epoch_quantum_us, now_us) Convenience funcs bundle common patterns (spawn-actor-and-register- mailbox, subscribe-to-kind, etc.) so a 4-modality scene fits in fewer lines than the wiring it composes. Composes feedback-build-intelligence-never-strip-features (build the composite once, reuse everywhere) + feedback-no-false-ok- substrate-honesty-audit (each sub-primitive's own smoke proves it works; this primitive's smoke proves the WIRING composes).