Module handler 

Step handlers — the Rust replacement for Java’s reflective arity-matched SAM invocation (Execute.invokeHandler/samMethod). A handler is a boxed closure over (state, args); arity is validated at the constructor. StepReturn carries the sync-or-Future channel (the analog of “an Object that might be a CompletableFuture”).

Structs

Handler

A registered step handler: a closure over (state, args_after_state).

Enums

StepOutput

What a handler produced. A stimulus yields the whole next state, which is opaque to the core — it is threaded between a file’s steps and replaced wholesale, never compared, serialized, or inspected. A sensor yields the value to compare against the document (None = no assertion).

StepReturn

The sync-or-async return channel.

Type Aliases

HandlerReturn

A handler’s resolved return: Ok(None) = “no assertion” (Java null), Ok(Some(v)) = a value, Err(_) = an author-signalled failure (Java throw).