hope-voice-api/AGENTS.md

Voice — Real-time Voice Assistant

A single-container voice assistant built on LiveKit Agents. Speaks and listens in real time using Azure Speech (STT + TTS) with models hosted by OpenWebUI (xNAS) for reasoning.

Architecture

One Docker container runs four processes via supervisord:

1. LiveKit server — open-source WebRTC media transport (port 7880 TCP, 7882 UDP muxed media)
2. Voice agent — Python LiveKit Agents pipeline: Azure STT → LLM (OpenWebUI) → Azure TTS
3. Web frontend — static HTML served by nginx (port 9178 by default)
4. Media server — FastAPI music library/player coordinator (port 8092 internal, proxied at /media/api/)

Browser ──WebRTC──► LiveKit Server ──audio──► Agent
   ▲                                              │
   └────────── audio ◄────────────────────────────┘
                        Azure STT → LLM (OpenWebUI) → Azure TTS

Browser ──HTTP──► nginx /media/api/ ──► Media server ──► yt-dlp/ffmpeg ──► ./media
   └────── audio element ◄── /media/files/ (nginx static, Range) ──────────┘

Quick Start

# 1. Set your Azure Speech key (already in ~/.hermes/.env as AZURE_SPEECH)
export AZURE_SPEECH_KEY=$(grep '^AZURE_SPEECH=' ~/.hermes/.env | cut -d= -f2)

# 2. Build and start
docker compose up --build -d

# 3. Open the web UI (self-signed cert: accept the browser warning once)
# https://<host-ip>:9178

LAN access requires firewall rules: 9178/tcp (UI + signaling), 7882/udp (WebRTC media), 7881/tcp (media TCP fallback).

Ports

Port	Protocol	Service	Access
7880	TCP	LiveKit HTTP/WS	internal only (proxied via nginx at /livekit/)
7881	TCP	LiveKit RTC media (TCP fallback)	LAN
7882	UDP	LiveKit RTC media (muxed)	LAN
8092	TCP	Media server (library, player state, stream proxy)	internal only (proxied via nginx at /media/api/)
9178	TCP	Web frontend (HTTPS)	LAN

Configuration

All config lives in .env (git-ignored). See .env.example for the full list.

Key variables:

• AZURE_SPEECH_KEY — Azure Speech resource key
• AZURE_SPEECH_REGION — default eastus
• AZURE_TTS_VOICE — default voice (en-US-Ava:DragonHDOmniLatestNeural)
• LLM_BASE_URL — OpenAI-compatible endpoint (default http://192.168.86.2:3005/api, OpenWebUI)
• LLM_MODEL — default model (default qwen2.5-vl-3b; switchable live from the web UI)
• LLM_API_KEY — OpenWebUI API key (bears sk-…)
• YTDLP_COOKIES — optional path to a cookies.txt inside the container (e.g. /data/media/cookies.txt) for reliable YouTube downloads

Media Player

Hope can play music on the web UI's media player: YouTube Music search → yt-dlp download → ffmpeg transcode to mp3 → nginx static streaming (HTTP Range) back to the browser's <audio> element. Live audio stream URLs (internet radio) are added to the library and proxied over HTTPS by the media server (mixed-content safe).

• The permanent library lives in ./media (bind-mounted to /data/media): files/ mp3s, thumbs/ cover art, jobs/ download status, library.json.
• web/media_server.py owns the library, search, download jobs (one at a time), and per-room player desired state. The browser is the actual player: it polls GET /media/api/state?room=…, reconciles, and reports real playback back via POST /media/api/report.
• Hope's tools live in agent/media_mcp.py (MCP, id "media"): search_music, play_song, offer_song_choices, pause_music, resume_music, stop_music, skip_song, seek_music, now_playing, list_library, add_stream. The MCP process is spawned per session with MEDIA_ROOM set to the LiveKit room name, scoping player state per room.
• Music and conversation are mutually exclusive. When a track plays, the UI reports {type: "media_state", state: "playing"} on data-channel topic "media-control" and the agent disables its mic (_apply_listening in agent.py). Engaging Hope (Start conversation / text message) pauses the music; ending the conversation resumes what was playing. Voice commands (pause/skip/…) work whenever the conversation is active.

Voice Selection

The web UI includes a voice picker that sends the selected voice to the agent via LiveKit data channel. The agent updates its TTS voice in real time without restarting.

Supported voices: any Azure Neural voice. See https://learn.microsoft.com/en-us/azure/ai-services/speech-service/language-support?tabs=en-us#neural-voices

SSML / Expressive Speech

The TTS layer wraps output in SSML. The default Azure Dragon HD Omni voice recognizes inline style markers such as [appreciative], [whispering], and [Neutral]; the agent prompt allows these markers while keeping responses short and conversational.

Agent Prompt

The LLM is instructed to:

• Speak as if talking to someone, not writing for them to read
• Keep responses to 1-3 sentences
• Use contractions, natural fillers sparingly
• Never use markdown, lists, or formatting
• Spell out numbers and abbreviations

Testing

# Verify the container is running
docker compose ps

# Check all logs (single service: "voice")
docker compose logs -f voice

# Tail individual process logs via supervisord stdout
docker exec voice tail -f /dev/stdout

# Test TTS directly (outside the agent)
curl -s "https://eastus.tts.speech.microsoft.com/cognitiveservices/v1" \
  -H "Ocp-Apim-Subscription-Key: $AZURE_SPEECH_KEY" \
  -H "Content-Type: application/ssml+xml" \
  -H "X-Microsoft-OutputFormat: audio-24khz-48kbitrate-mono-mp3" \
  --data-binary '<speak version="1.0" xmlns="http://www.w3.org/2001/10/synthesis" xml:lang="en-US"><voice name="en-US-Ava:DragonHDOmniLatestNeural">[appreciative] Test complete.</voice></speak>' > /tmp/test.mp3

File Layout

~/dev/voice/
├── AGENTS.md            ← you are here
├── .env.example         ← config template (copy to .env)
├── .gitignore
├── docker-compose.yml   ← single container
├── Dockerfile           ← multi-stage build
├── entrypoint.sh        ← regenerates self-signed cert with LAN IP at start
├── livekit.yaml         ← LiveKit server config
├── nginx.conf           ← HTTPS UI + /livekit/ WS proxy + /media/ (static + API)
├── supervisord.conf     ← process manager (livekit, agent, nginx, token-server, media-server)
├── certs/               ← persisted self-signed cert (volume mount)
├── media/               ← permanent music library (bind-mounted to /data/media)
│   ├── files/           ← transcoded mp3 tracks (nginx-served, HTTP Range)
│   ├── thumbs/          ← cover art
│   ├── jobs/            ← download job status snapshots
│   └── library.json     ← library metadata (permanent)
├── agent/
│   ├── agent.py         ← LiveKit Agents voice pipeline
│   ├── media_mcp.py     ← Hope's music tools (YouTube Music via media server)
│   ├── pyproject.toml   ← Python deps (uv)
│   └── uv.lock          ← locked dependency versions
└── web/
    ├── index.html       ← single-page voice UI (+ music panel)
    ├── app.js           ← LiveKit client logic (+ player reconciliation)
    ├── media_server.py  ← FastAPI library/search/download/player state
    ├── token_server.py  ← LiveKit token endpoint (mints room name)
    ├── manifest.json    ← PWA manifest
    ├── favicon.svg      ← site icon
    ├── livekit-client.umd.js ← vendored LiveKit JS SDK (no CDN)
    └── style.css        ← minimal dark theme

Conventions

• Single container. All services (LiveKit, agent, web, token endpoint) run in one Docker container via supervisord. No multi-service compose.
• No published UDP ports in compose. LiveKit binds its media ports directly on the host network (network_mode: host). This avoids the docker-proxy process explosion that hit hope-webui.
• Agent dispatch via roomConfig token claim. LiveKit only dispatches agents to rooms that request them; a room auto-created by a participant join gets none. The token endpoint embeds roomConfig.agents in every JWT so the agent is dispatched when the browser joins. Do not pre-create rooms instead — if the agent worker isn't registered yet (first ~15s after container start), the dispatch silently fails and never retries; joining later re-fires it. The token server now pins the room name to "voice-room" server-side and no longer accepts arbitrary room names.
• Interruption mode must be "vad". interruption={"mode": "adaptive"} requires the LiveKit Cloud barge-in service (agent-gateway.livekit.cloud) and spams 401 retries on self-hosted setups.
• Mic requires HTTPS. Browsers block getUserMedia outside a secure context. nginx serves the UI on WEB_PORT (9178 by default) over HTTPS with a self-signed cert whose SAN includes the detected LAN IP. The cert is persisted in ./certs/ and the LiveKit WS is proxied through nginx at /livekit/.
• No CDN dependencies. livekit-client UMD bundle is vendored into web/; LAN devices may have no internet access.
• Transcripts flow over the data channel. The agent publishes {type: "transcript", role, text} JSON on topic "transcript"; the UI renders them. Voice changes flow the other way as {type: "set_voice", voice} on topic "voice-control".
• Models come from OpenWebUI. The LLM endpoint is OpenWebUI's OpenAI-compatible API at LLM_BASE_URL (default http://192.168.86.2:3005/api); chat goes to /api/chat/completions and the model list comes from GET {LLM_BASE_URL}/models. Plain /v1/* routes are NOT routed on that instance (they serve the SPA). Pipe models (opencode_go_messages.*, go-chat.*, go-responses.*) currently fail upstream with auth errors; the local llama.cpp/vLLM models (e.g. gemma-4-e4b, qwen2.5-vl-3b, qwen3.8-27b) work.
• Reasoning models may hide their answer. Gemma (and similar) sometimes spends tokens on hidden reasoning before producing content. The agent implements this with max_completion_tokens=1000 and a HopeLLM subclass that wraps the LLM stream, falling back to reasoning_content if content is empty.
• Azure TTS uses SSML, not JSON. The REST endpoint requires Content-Type: application/ssml+xml. The LiveKit Azure plugin handles this internally.
• Voice changes are live. The web UI sends a data message to the agent; the agent calls tts.update_options(voice=...) without restarting. The agent filters data messages by topic ("voice-control") before processing.
• Model changes are live too. The agent fetches the chat-capable model list (HopeLLM filters out embedding/reranker ids) and publishes {type: "models", models, selected}; the UI's settings sheet renders a picker and sends {type: "set_model", model}, which calls HopeLLM.update_options(model=...) (mutates self._opts.model) and acks with {type: "model_changed", model}. The choice persists in the browser's localStorage.
• All supervisord programs log to /dev/stdout so docker compose logs -f voice shows everything. Individual process logs are no longer written to files.
• Music downloads are mp3, not YouTube streams. The media server transcodes with yt-dlp (-x --audio-format mp3 --audio-quality 192K --embed-thumbnail) into /data/media/files/{video_id}.mp3; nginx serves those files as statics with native HTTP Range, which is what makes seeking work in the <audio> element. Never point the player at YouTube directly.
• External stream URLs are proxied, never played directly. An http:// radio URL would be blocked as mixed content on the HTTPS UI, so GET /media/api/stream/{id} re-serves the upstream over HTTPS with Range passthrough. Downloaded tracks on that endpoint just redirect to /media/files/.
• Player state is per-room desired state, reconciled by the browser. The media server never streams to anything; it records what SHOULD play per LiveKit room and the browser polls and reports back. Track ids for YouTube tracks are the video ids (dedupe by video_id); stream tracks get s<uuid>.
• Anonymous yt-dlp first, cookies when flaky. Search (ytsearch) and downloads work anonymously from a residential IP; if YouTube starts bot-blocking, drop a cookies.txt into ./media/cookies.txt and set YTDLP_COOKIES=/data/media/cookies.txt.

Git

Commit frequently. Conventional commits (feat:, fix:, chore:).