sim-lib-journal
sim-lib-journal is SIM's domain-free atomic content journal. It publishes
immutable content-addressed objects and advances one gapless, fenced head. The
backend contract has one atomic admission operation so durable implementations
can compose canonical table/cas without inventing another lock or store.
Entry kinds are open Symbol values and payloads are opaque ContentIds. The
crate contains no study, model, attempt, grading, or report vocabulary.