Text-to-Speech

Let the agent talk back in an actual human-sounding voice — used by the "play this message" speaker button in the web chat.

URL: /settings?tab=tts

Enabled

Master toggle. When off, no speaker icons disappear from the UI.

{ "tts": { "enabled": false } }

Provider

Which backend generates the audio. Both options reference an entry you already configured on the Providers page — the API key / base URL is read from there.

Value	Notes
openai	Uses an OpenAI API-Key provider from providers.json. Calls its /v1/audio/speech endpoint with one of OpenAI's TTS models.
mistral	Uses a Mistral API-Key provider from providers.json. Synthesises with Mistral's Voxtral voices.

The dropdown lists each matching provider as its own entry, e.g. OpenAI (My OpenAI) or Mistral Voxtral (Mistral Main). If no matching provider is configured, the option appears disabled.

The selected provider's id is stored in tts.providerId; tts.provider stores only the backend type:

{ "tts": { "provider": "openai", "providerId": "openai-main" } }

OpenAI model

Shown when provider is openai. The model is sent to the selected provider's /v1/audio/speech endpoint.

Value	Notes
gpt-4o-mini-tts	Newer, supports tone/style instructions. Recommended default.
tts-1	Classic, fast, cheap.
tts-1-hd	Higher-fidelity version of tts-1.

{ "tts": { "openaiModel": "gpt-4o-mini-tts" } }

OpenAI voice

Shown when provider is openai. One of OpenAI's preset voices (alloy, ash, ballad, coral, echo, fable, nova, onyx, sage, shimmer, …). The list is loaded live from the OpenAI catalog so the options stay in sync if OpenAI ships new voices.

{ "tts": { "openaiVoice": "nova" } }

OpenAI instructions

Only shown for gpt-4o-mini-tts. Free-form tone/style guidance for the voice model, e.g.:

Speak calmly, with a slight Viennese accent, medium pace.

Leave empty for the neutral default.

{ "tts": { "openaiInstructions": "" } }

Mistral voice

Shown when provider is mistral. The UI splits the choice into two side-by-side dropdowns:

• Speaker — one of the available Voxtral speakers, annotated with language (e.g. Nadia (German), Theo (English)).
• Mood — emotional color (neutral, happy, serious, …).

The list is fetched live from the Voxtral catalog when you open the panel. The two selections are combined into a single voice id and stored in tts.mistralVoice:

{ "tts": { "mistralVoice": "nadia-neutral" } }

Voice preview

A text field + play button at the bottom of each provider block. Enter any text, click the speaker icon, hear the current settings applied immediately — no need to save first. Stop playback by clicking the same button again.

Audio format

Output container format used for the synthesized audio in the web chat.

Value	Notes
mp3	Universal default.
wav	Uncompressed, large.
opus	Small.
flac	Lossless.

{ "tts": { "responseFormat": "mp3" } }