pub fn single_phase(view: &ErasedWorkflowView) -> Result<(), AssertionFailure>Expand description
Checks that a projection carries exactly one phase (§8.4).
“Exactly one” is structural in the typed view — phase is a single value by
type — so what is left to check on the erased form is that the phase is a
real value and not a null or a list of concurrent phases smuggled through
the serializer.