Interface RealtimeTranscript

Whether this is the final transcript for the turn (true) or an interim delta (false).

When true, this FINAL transcript REPLACES the previous final for the same in-flight turn — providers that STREAM their "completed" transcription (each event carrying the full growing text, e.g. Grok) set this so consumers collapse the stream into one in-place-updating turn instead of a stack of growing duplicates. Absent/false: a normal, append-worthy final.

Whose turn this transcript belongs to.

The transcribed text. For IsFinal: false events this is the incremental DELTA for the in-flight turn (drivers emit each new fragment, not a re-send of the accumulated text); for IsFinal: true it is the complete turn text.