# Jervis Voice Assistant — System Overview

> Single source of truth for the local voice-assistant system on Sam's home lab.
> Companion docs: **`agent-api.md`** (how to send a command / get a reply) and **`clients.md`** (type-it, web, Android gateways).
> Component repos: `voice_assistant` (ESP32 firmware), `voice_bridge` (STT bridge), `voice_agent` (this brain), `speech_piper` (TTS).

---

## What it does

A fully-local, private voice assistant. You say **"Hey Jervis"**, then a natural-language request; it answers, controls the house, manages your shopping list, and speaks back through your speakers. The **design principle: one LLM "brain"** decides what to do, and calls tools. Home Assistant is *one of those tools* — not the decision maker.

---

## Architecture

```
┌─ Input ───────────────────────────────────────────────────────────────┐
│  ESP32-S3  ("Hey Jervis" wake word, INMP441 mic, WS2812 LED ring)     │
│    └→ MQTT voice/audio_stream  (broker .13:1883)                      │
│  voice_bridge (docker .13) — wake word, buffer audio                  │
│    └→ HTTP :5000                                                      │
│  voice_whisper (docker .13, faster-whisper) — STT audio→text          │
│    └→ publish text → MQTT homeassistant/voice/text  (broker .30)      │
│  ALSO: any client → POST http://.13:8501/voice {text}  (see clients.md)│
└───────────────────────────────────────────────────────────────────────┘
                          │  text
                          ▼
┌─ Brain ── voice-agent (systemd service on .13:8501) ─────────────────┐
│  LLM = OmniRoute (OpenAI-compatible, tool-calling)                   │
│  Model: auto/best-fast                                               │
│  LLM decides intent → calls a TOOL:                                  │
│    • get_time / get_weather / answer          (Open-Meteo, LLM)      │
│    • add_shopping_item    → KitchenOwl API   (shopping list)         │
│    • control_ha / ha_service_cmd  → Home Assistant REST API          │
│    • feed_fish            → HA input_button.fish_feeder              │
│    • set_reminder         → HA persistent_notification               │
│    • speak_as(voice,text) → piper per-character voice                │
│    • play_music           → Mopidy (Spotify, WORKING)               │
│    • pause/stop/next      → Mopidy MPD (planned)                    │
└───────────────────────────────────────────────────────────────────────┘
                          │  reply text
                          ▼
┌─ Output ─────────────────────────────────────────────────────────────┐
│  piper_tts (docker .13) → speak_direct.sh (pure-python resampler snapcast_send.py) → Snapcast → speakers  │
└───────────────────────────────────────────────────────────────────────┘
```

**Key design decision:** the agent is the single brain; **Home Assistant is a passive device the agent commands via its REST API** — no per-action HA automation/subscription is needed for the agent's commands (one long-lived HA token enables all HA control).

---

## Components (`host/IP/port/repo`)

| Component | Host/IP | Port | Repo / path | Role |
|---|---|---|---|---|
| ESP32-S3 | — | — | `sam/voice_assistant` | Wake word, mic, LED |
| voice_bridge | `.13` | docker | `sam/voice_bridge` | Wake word + audio buffer |
| voice_whisper | `.13` | `:5000` | `sam/voice_bridge` | faster-whisper STT |
| **voice-agent** | `.13` | **`:8501`** | `sam/voice-assistant` | LLM brain + tools |
| OmniRoute | `.13` | `:20129` (API) | — | LLM gateway (OpenAI-compatible) |
| piper_tts | `.13` | `:10200` | `sam/speech_piper` | TTS (Wyoming) |
| Snapcast | `.13` | `:1780` | — | Multi-room audio |
| Mopidy / librespot | `.13` | `:6600`/`:6680` | — | Music: Spotify via gst-plugin-spotify + device-auth credentials |
| Home Assistant | `.30` | `:8123` (REST) | — | Home control |
| KitchenOwl | `.35` | `owl.lab.audasmedia.com.au` | — | Shopping list |
| mosquitto | `.13` + `.30` | `:1883` | — | MQTT brokers |

---

## Data flow summary

1. ESP32 streams audio to **voice_bridge** (MQTT on `.13`).
2. **voice_bridge** detects the wake word, buffers, sends to **voice_whisper**.
3. **voice_whisper** (faster-whisper) returns text.
4. Text is published to MQTT `homeassistant/voice/text` (broker `.30`) **and/or** POSTed to the agent.
5. **voice-agent** (LLM) decides intent and calls a tool.
6. Reply text → **piper** → **Snapcast** → speakers.

---

## Music playback (Mopidy + Spotify) — working 2026-08-30

`play_music` → Mopidy (MPD :6600) → Spotify → Snapcast → speakers.

**Two pieces were required (both were the blocker):**
1. **`gst-plugin-spotify`** — the `spotifyaudiosrc` GStreamer element that decodes `spotify:track` URIs. Added `pkgs.gst_all_1.gst-plugins-rs` to `systemd.services.mopidy.environment.GST_PLUGIN_PATH` in `.13` `configuration.nix` (also isolated Mopidy's GST path to its own 1.28.4 plugins + a void `GST_PLUGIN_SYSTEM_PATH` to avoid the system pipewire plugin poisoning the registry).
2. **`credentials.json`** — generated via librespot **device-authorization flow** (`get_creds_device`, built from librespot dev branch — has `DeviceAuthClient`). The old PKCE redirect flow (`get_creds`) is **broken** in librespot (deterministic `code_verifier was incorrect`). Device flow prints `spotify.com/pair` + code; user approves on any device. File at `/var/lib/mopidy/spotify/credentials-cache/credentials.json` (mopidy-owned).

Also fixed along the way: mopidy-local disabled (empty `library.db` crashed search: `no such table: tracks`); Mopidy-Spotify creds re-authed via mopidy.com (old grant revoked).

**librespot (NixOS speaker's Spotify Connect output) is separate and untouched.**

## Run / manage

- Agent service (persistent, auto-starts): `systemctl status voice-agent` (NixOS systemd unit declared in `/etc/nixos/configuration.nix`). Restart: `sudo systemctl restart voice-agent`.
- Logs: `journalctl -u voice-agent` / `journalctl -u snapserver`.
- Firewall: port `8501` is in `allowedTCPPorts` in the NixOS config.

## Repository map (other related projects)

- `sam/voice_assistant` — ESP32 firmware
- `sam/voice_bridge` — STT bridge + whisper
- `sam/speech_piper` — TTS scripts/models → Snapcast
- `sam/voice-assistant` — **this** overview + API contract + clients
- `sam/family_home_lab` — console portal / dsh
---

## Diagrams

- **Interactive map** (Archify HTML, pan/zoom/search/dark-light): [`voice-assistant-map.html`](./voice-assistant-map.html)
  - Published live: <https://maps.lab.audasmedia.com.au/homeassistant/docs/voice-assistant-map.html>
- **Mermaid source**: [`voice-assistant.mmd`](./voice-assistant.mmd) · rendered **SVG**: [`diagrams/voice-assistant.svg`](./diagrams/voice-assistant.svg)
- **Archify JSON IR** (single source of truth for the interactive map): [`archify/voice-assistant.architecture.json`](./archify/voice-assistant.architecture.json)

> Regenerate the interactive map from the JSON:
> `node ~/.agents/skills/archify/bin/archify.mjs deliver architecture docs/archify/voice-assistant.architecture.json docs/voice-assistant-map.html --quality showcase --json`