Voice & assistants

Bifrost can be driven hands-free two ways: spoken voice (a built-in pipeline) and AI assistants (an embedded MCP server). Both go through the same shared service layer as the web UI and REST API, so they can't drift from it. Everything here is optional and degrades gracefully, and the models are pluggable — they can run entirely on your own hardware, or not at all.

How a spoken command flows

1. Capture. Hold the dashboard's push-to-talk mic (phone/desktop/tablet), or — on the wall tablet — just say the wake word ("bifrost").
2. Transcribe (STT). The audio becomes text: on-device on the kiosk (offline Vosk), or server-side via the configured transcription model (POST /api/voice/listen).
3. Resolve & act — native first, then fall back:
4. Deterministic grammar (no model, always on) — parses power, brightness, color, color-temperature, volume, mute, transport, scenes, and relative nudges, resolves targets by room/device name, and handles compound commands ("dim the office and pause the kitchen"). Fast and offline.
5. TV content — "open Netflix on the bedroom TV" / "play Bob's Burgers on the living room TV" resolves to an app launch on that TV (matched by name; a title with no matching app opens the TV's last-used app as the best guess).
6. LLM fallback — anything still unparsed is handed to the chat model (OpenAI-compatible tool-calling), which maps it to the same internal command and dispatches it the same way.
7. Home Assistant Assist — if HA is connected and the LLM didn't resolve it, the clause is delegated to HA Assist (the long tail, e.g. "play Bob's Burgers on the TV").
8. With no models configured, the grammar still handles what it can; the rest comes back as "I didn't understand."
9. Talk-back (TTS). The spoken reply is synthesized by the tts model and played back. Optional — text and command control never depend on it.

AI model endpoints

Configure these under Settings → Voice & AI. There are three roles, each an independent OpenAI-compatible HTTP endpoint (base URL + model + optional key):

Role	What it does	Used by
transcription	speech-to-text	POST /api/voice/listen (clients that upload audio)
chat	the LLM fallback / natural-language understanding	any command the grammar can't parse
tts	text-to-speech	spoken replies (talk-back)

Point them at whatever you run — a local Ollama / faster-whisper / Piper / Kokoro / vocals-mcp, or any hosted API. The Test button probes the endpoint's /models. Each role degrades on its own: unset just means that capability is off (e.g. /listen returns 503 until a transcription model is set), while the deterministic grammar always works over text. Models are never mandated — Bifrost ships no weights and no runtimes.

Talk-back (spoken replies)

POST /api/voice/speak turns a reply into audio via the tts endpoint and plays it (in the browser and on the kiosk; opt out per client). Multi-sentence replies stream — the first sentence starts playing while the rest synthesize, so a long reply doesn't wait on the whole thing. Pair it with an OpenAI-compatible TTS server that supports voice cloning (e.g. vocals-mcp) to have Bifrost answer in a voice you choose.

The wall-tablet kiosk

The bifrost-kiosk app makes a mounted tablet a hands-free fixture: an always-on, offline wake word plus push-to-talk, with replies played natively. It's the display dashboard and the voice satellite in one device-owner app. See Pair the wall tablet.

AI assistants (MCP)

The embedded MCP server at /mcp exposes the whole home as assistant tools — lights, media, power, rooms, scenes, remotes, casting — resolved by name, not just id. It's the same shared service layer behind the voice pipeline, gated by the same Bearer API keys as /api/v1. Point any MCP client (e.g. a desktop assistant) at it for natural-language control.

Privacy & where things run

Nothing leaves your network unless you point a model endpoint at a cloud service — the deterministic grammar is offline, the kiosk's wake word is on-device, and STT/chat/TTS can all be local. All voice endpoints are gated by the same Bearer API keys as /api/v1.

API reference

The HTTP endpoints (/api/voice/command, /api/voice/listen, /api/voice/speak, /api/voice/vocabulary) and their request/response shapes are documented under Public API → Voice control; the assistant tools under MCP server.