Module error 

Error types for the Murk simulation framework.

Maps the error code table from HLD §9.7 to Rust enums, organized by subsystem: step (tick engine), propagator, ingress, and observation.

Enums

IngressError

Errors from the ingress (command submission) pipeline.

ObsError

Errors from the observation (egress) pipeline.

PropagatorError

Errors from individual propagator execution.

StepError

Errors from the tick engine during step().