ExperimentalA unique identifier for the message this chunk belongs to.
All chunks belonging to the same message share the same messageId.
A change in messageId indicates a new message has started.
A single item of content
Optional_The _meta property is reserved by ACP to allow clients and agents to attach additional metadata to their interactions. Implementations MUST NOT make assumptions about values at these keys. This field is chunk-scoped.
See protocol docs: Extensibility
A streamed item of message content.