Voice Assistant

Pick brAIn as a conversation agent under Settings → Voice Assistants and every Assist pipeline — voice satellites, the chat dialog, the mobile app — routes through Claude with full knowledge of your home.

Why it’s fast

Typical commands answer in ~3–5 seconds, and replies stream, so TTS starts speaking at the first sentence on streaming-capable pipelines. Two mechanisms:

Fast mode (assist_fast_mode, default on): a pool of pre-warmed Claude worker processes — one per active conversation plus a hot spare — so voice turns skip CLI boot and MCP handshake entirely. Budget ~150–300 MB RAM per warm worker (max 3). If a worker ever errors, the add-on falls back to a one-shot spawn automatically.
The area map: a cached area → entity map (controllable domains plus Weather and People) is spliced into the system prompt, so “turn off the kitchen lights” acts directly — no lookup turns.

binary_sensor.brain_system_assist_healthy reports pool health (worker count, spare, last-request latency), and brain doctor probes the whole path end-to-end.

Personalities

Each conversation agent you create gets its own name, model, and system prompt — a butler, a snarky roommate, a kid-friendly narrator. Prompts are layered deliberately:

Your personality leads, and explicitly owns identity, tone, and verbosity.
An operational block follows — tools, the area map, timezone, routing rules — deliberately identity-free so it can’t fight your persona.

Without a personality, a built-in default applies (“helpful, efficient, 1–2 short sentences”). With one, that default is dropped entirely — so if your persona should stay brief for TTS, say so in the persona: “…no matter how excited you get, keep spoken replies under two sentences.”

New agents default to Claude Haiku for snappy responses; pick any model per agent in the integration options.

You can run several at once, each with its own name, model, personality and deny-list:

"Jarvis"        You are Jarvis, a dry British butler. Address me as "sir".
                However excited you get, keep spoken replies under two sentences.
                Blocked: nothing.

"Kids' speaker" You are a cheerful helper for a 7-year-old. Short, simple words.
                Never mention alarms or locks; if asked, say you'll fetch a grown-up.
                Blocked: lock.unlock, lock.open, alarm_control_panel.*, script.*

The deny-list is enforced where every control tool funnels through, so it holds no matter how the request is phrased.

Because voice reads the same memory as everything else, an agent already knows the house it’s talking about:

“Turn on the beacon.” → memory says the beacon is the office lamp.

“It’s too cold in here.” → memory says the heating is a heat pump on weather compensation, not a boiler, so it raises the flow temperature instead of asking for a target temperature that would do nothing.

Conversation memory

While the same Assist chat or voice session stays open, Home Assistant keeps the same conversation_id — and the add-on resumes the same Claude session for each turn, so follow-ups genuinely remember the conversation. A new session starts a clean slate; brain.clear_conversation resets one (or all) manually. If session resume isn’t possible, the integration replays recent turns instead, so follow-ups still work with shorter memory.

Voice is also how the house learns: say “remember that we call the office lamp ‘the beacon’” and it’s stored instantly.

Safe by default: tool scoping

Voice can control everything but can’t run shell commands or edit files — assist_tool_access: mcp_only is the default. Two more dials:

assist_max_turns caps agentic loops per request (default 8) so a misunderstood command can’t spiral. It stays deliberately modest where the other channels are generous: latency is the product for voice, and a twenty-turn voice command is a failed interaction whatever it answers.
Per-agent service deny-lists (e.g. forbid lock.unlock for the kids’ satellite): every control tool funnels through one chokepoint, so the deny-list covers all of them. See the Reference for the option syntax.

With Power Tools installed, voice requests can also reorganize — “create a zone for the gym”, “hide the child-lock switches” — with the same validation and admin gating as everywhere else.