Module observer 

Execution Observer Module

An always-on, per-task callback for aggregation — counters, histograms, spans — as distinct from crate::ExecutionTrace, which is a per-request allocation you persist.

This exists because the eight sync built-ins (map, validation/validate, parse_json, parse_xml, publish_json, publish_xml, filter, log) are dispatched inside a private method on the workflow executor and never reach the function registry. A host can time its own registered handlers by wrapping their bodies, but it cannot time those eight at any price, and so cannot tell how much of a message’s wall clock was spent inside the engine versus inside its own handlers.

Structs

TaskEvent

One finished task.

Traits

ExecutionObserver

Receives one callback per dispatched task.