Transcription.Finished is always null for InputTranscription — never set to true when user speech ends

[kkdubey]

When using the Live API with InputAudioTranscription enabled, serverContent.InputTranscription.Finished is never true. It remains null for every InputTranscription message, including the final transcription at the end of a user's utterance. This makes it impossible to determine when a user's speech transcription is complete.

Environment:

• Package: Google.GenAI v1.5.0
• Runtime: .NET 8
• Model: gemini-2.5-flash-native-audio-latest

Steps to Reproduce:

using Google.GenAI;
using Google.GenAI.Types;

Client client = new(apiKey: "VALID_API_KEY");

LiveConnectConfig config = new() {
ResponseModalities = [Modality.Audio],
InputAudioTranscription = new AudioTranscriptionConfig(),
OutputAudioTranscription = new AudioTranscriptionConfig(),
SpeechConfig = new SpeechConfig {
VoiceConfig = new VoiceConfig {
PrebuiltVoiceConfig = new PrebuiltVoiceConfig {
VoiceName = "Zephyr"
}
}
}
};

AsyncSession session = await client.Live.ConnectAsync(
"gemini-2.5-flash-native-audio-latest", config);

// Consume SetupComplete
await session.ReceiveAsync();

// Send audio and receive messages...
while (true) {
LiveServerMessage message = await session.ReceiveAsync();
if (message?.ServerContent?.InputTranscription != null) {
var t = message.ServerContent.InputTranscription;
// t.Text contains transcription text ✓
// t.Finished is ALWAYS null — never true, even at end of utterance ✗
Console.WriteLine($"Text: '{t.Text}', Finished: {t.Finished}");
}
}

Impact:

Without a working Finished flag, there is no reliable way to know when a user's speech transcription is complete.

[kkdubey]

@shivvaam0001 Any update in this issue

[shivvaam0001]

Hi @kkdubey
Thank you for bringing this to our attention. We truly appreciate you flagging this issue, we will file a bug internally.

Thanks!