Serialization utilities for workflow events.

Provides binary (ETF) serialization for event persistence and transport. Events are plain structs and serialize naturally via Erlang's external term format.

Binary Serialization (ETF)

The primary serialization format uses :erlang.term_to_binary/1 which handles all Elixir/Erlang terms natively. This is the recommended format for same-system persistence (ETS, Mnesia, file-based stores).

events = workflow.uncommitted_events
binary = Serializer.to_binary(events)
{:ok, ^events} = Serializer.from_binary(binary)

Custom Events

Custom event structs from external Invokable implementations serialize and deserialize automatically via ETF — no registration or adapter is needed. The only requirement is that the struct's module atom exists in the VM at deserialization time (which is guaranteed when using :safe mode and the application code is loaded).

Custom events should implement the Runic.Workflow.EventApplicator protocol so that Workflow.apply_event/2 knows how to fold them into the workflow during replay via Workflow.from_events/1.

Considerations

• Binary format is tied to the Erlang VM and struct module names. Schema migrations require versioned deserialization.
• For cross-language interop, implement a JSON adapter at the Store level using the event struct fields directly (all fields are JSON-safe primitives except value in FactProduced, which is arbitrary user data).
• For event schema versioning, add a version field to custom event structs and handle upcasting during deserialization at the Store adapter level.