Module semantics 

What happens when the system is in some state and something happens to it. States here are Conditions, sets of concrete states, so one step answers for all of them at once. Story planning and the flow graph both step through a suite with perform.

Structs

Outcome

Functions

perform

Perform action in state.

perform_among

perform, looking only at candidates: every transition the action might set off must be among them. Searches that perform the same actions over and over work these out once.

seen_by

The state an expectation with trigger checks its Given against when action happens in state: the action’s other changes already made.

settle

Apply every invariant whose Given certainly holds, until nothing changes. Invariants that one of exempt_by overrides are skipped.