message_to_events

Replay a finalized message as a synthetic event lifecycle.

For a message returned whole (from a graph node, checkpoint, or cache), produce the same message-start / per-block / message-finish event stream a live call would produce. Consumers downstream see a uniform event shape regardless of source.

Text and reasoning blocks emit a single content-block-delta with the full accumulated content. Already-finalized blocks (tool_call, server_tool_call, image, etc.) skip the delta and rely on the content-block-finish event alone.