Reserved. Bidirectional streaming is reached through Runner.runLive(),
not through this value: runLive itself calls createRunConfig, which
rejects BIDI. Use StreamingMode.SSE for incremental responses.
Deliver the response as a single event once the turn completes.
Deliver the response incrementally, as a series of partial events followed by a final event carrying the complete text.
The streaming mode for the run config.