Host-side handle to one open TTS provider stream (pipeline mode). Produced by the host's provider resolver at session start; user code never constructs one.
Interrupt immediately (barge-in). Emits done synchronously.
done
Signal "no more text this turn". Emits done when fully synthesized.
Push text deltas from the LLM. Provider may synthesize as chunks arrive.
Host-side handle to one open TTS provider stream (pipeline mode). Produced by the host's provider resolver at session start; user code never constructs one.