OptionalinboundDurability on: the inbox record holding the message (read back from the journal).
OptionalcauseDurability: where the answered step's send keys continue (re-derived on the replica that resumes it).
OptionalmessageDurability off: the encoded inbound message (raw stripped), when it fits handover.maxAnswerBytes.
OptionalinteractionButton/callback answers: the interaction projection (id, data, respondBy).
Optionalbodyctx.body after the before('message') hooks (a voice transcript survives the hand-over).
Optionaltypectx.type after the hooks, when they changed it (a transcribed voice note becomes 'text').
Optionallangctx.lang as resolved for the message.
When it was captured (epoch ms).
See FlowCheckpoint.answer. Stores persist it opaquely, as JSON.