ConvertToProtocolEventOptions

Converts a raw [ns, mode, payload, meta?] stream chunk emitted by graph.stream() into one or more CDDL-aligned ProtocolEvents.

Most modes produce a single event. values chunks carrying StreamChunkMeta.checkpoint additionally produce a companion checkpoints event immediately after the values event, so clients that subscribe only to checkpoints can build a branching timeline without also paying for full-state values payloads, and clients that subscribe to both can correlate the pair by (namespace, step) or by adjacent seq numbers.

Returns an empty array for stream modes that have no protocol mapping.