push

Route an event through all transformers, then append to the main log.

Each transformer's process() is called in registration order. If any transformer returns False, the event is suppressed from the main log, but transformers that already saw it keep their side effects.

On the root mux, seq is assigned right before an event enters the main log, not before the transformer pipeline runs. This ensures that events auto-forwarded from StreamChannels during process() get earlier seq numbers than the original event, preserving monotonic ordering in the root log. Child muxes do not assign seq, so subgraph forwarding can share event objects without mutating their envelopes.