Voxtral chat with audio input (streaming)

Exercises the audio-input branch of MistralClient.IChatClient over the streaming path: 1. Use Mistral TTS to synthesize a short utterance. 2. Stream a chat completion from VoxtralModels.SmallChat with the audio bytes attached as a Meai.DataContent with audio/wav media type. 3. Assert that the accumulated Meai.ChatResponseUpdate.Text mentions the original utterance.

Skips when MISTRAL_API_KEY is unset, the account has no voices, TTS refuses the request, or the Voxtral chat model isn't enabled for this account.

This example assumes using Mistral; is in scope and apiKey contains your Mistral API key.

using var client = new MistralClient(apiKey);

VoiceListResponse voices;
try
{
    voices = await client.AudioVoices.ListAllVoicesAsync();
}
catch (ApiException ex)
{
    throw new AssertInconclusiveException(
        $"Mistral voice listing unavailable (HTTP {(int?)ex.StatusCode}); skipping live streaming chat-with-audio test.",
        ex);
}

if (voices.Items is not { Count: > 0 } items)
{
    throw new AssertInconclusiveException(
        "No voices available on this Mistral account; skipping live streaming chat-with-audio test.");
}

const string utterance = "The quick brown fox jumps over the lazy dog.";

SpeechResponse speech;
try
{
    speech = await client.AudioSpeech.SpeechAsync(new SpeechRequest
    {
        Input = utterance,
        VoiceId = items[0].Id.ToString(),
        ResponseFormat = SpeechOutputFormat.Wav,
    });
}
catch (ApiException ex)
{
    throw new AssertInconclusiveException(
        $"Mistral TTS unavailable for this account (HTTP {(int?)ex.StatusCode}); skipping live streaming chat-with-audio test.",
        ex);
}

var audioBytes = Convert.FromBase64String(speech.AudioData);

Meai.IChatClient chatClient = client;
var updates = chatClient.GetStreamingResponseAsync(
    [
        new Meai.ChatMessage(Meai.ChatRole.User,
        [
            new Meai.TextContent("Repeat exactly what the speaker said in the audio, with no extra commentary."),
            new Meai.DataContent(audioBytes, mediaType: "audio/wav"),
        ]),
    ],
    new Meai.ChatOptions
    {
        ModelId = VoxtralChatModelId,
    });

var deltas = new List<string>();
try
{
    await foreach (var update in updates)
    {
        if (!string.IsNullOrEmpty(update.Text))
        {
            deltas.Add(update.Text);
        }
    }
}
catch (ApiException ex) when (ex.StatusCode is System.Net.HttpStatusCode.NotFound
                                  or System.Net.HttpStatusCode.Forbidden
                                  or System.Net.HttpStatusCode.BadRequest)
{
    throw new AssertInconclusiveException(
        $"Voxtral chat model '{VoxtralChatModelId}' not enabled for this account (HTTP {(int?)ex.StatusCode}); skipping live streaming chat-with-audio test.",
        ex);
}

var combined = string.Concat(deltas);