voicesim

Fakes ElevenLabs Conversational AI (the signed-URL mint and the conversation socket) and OpenAI's pcm speech and transcription. Every answer is canned: tones for audio, four scripted agent lines, one fixed caller transcript. Keys are accepted and never checked: a dev shim, never expose it. Code: services/sims/voicesim, console apps/sims/src/voice.

Run it

• Opt-in: haven up +voice (sticky). Runs in the go lane by default (see sims).
• Already on? haven sim voice status answers with the base URLs; the seeded org then has an ElevenLabs provider at voicesim, no clean instance needed.
• Console: https://voice.<slug>.langwatch.localhost (calls, transcripts, events, Clear calls); haven status shows the loopback port.
• Unless .env names ELEVENLABS_BASE_URL, the overlay sets it to http://127.0.0.1:<port>, a dummy ELEVENLABS_API_KEY when none is set, and VOICE_UNSAFE_ALLOW_LOOPBACK_PROVIDERS=1.
• The seed then stores the ElevenLabs provider row at voicesim. Standalone: make service svc=voicesim (:5591).

The dev switch

VOICE_UNSAFE_ALLOW_LOOPBACK_PROVIDERS (packages/config/src/deployment-facts.ts) is the only thing that lets the product call a loopback voice host. One rule decides it, isAllowedElevenLabsUrl in @langwatch/model-provider-contract, used by the seed's keys schema, the gateway's credential read and the signed-URL check. On, it admits http/ws on 127.0.0.1 or localhost with an explicit port, nothing else. Off (every production process), those three points refuse loopback. The registry schema never carries the switch, so the settings form still refuses a loopback base URL.

OpenAI audio is not redirected: the product has no audio-only OpenAI base URL, and OPENAI_BASE_URL would move every model call.

Inspect and assert

GET /_sim/api/calls     # newest first: turns, frame counts, protocol events
DELETE /_sim/api/calls  # forget every call (204); ids keep counting
GET /_sim/api/status    # stack, call count, the base URLs to point a provider at
GET /v1/convai/conversation/get-signed-url?agent_id=<id>
POST /v1/audio/speech   POST /v1/audio/transcriptions

A call id is conv_voicesim_0001, 0002, ... An unfaked provider path answers 404.

Seed and reset

• VOICESIM_SEED=1 (haven sets it) records one finished two-turn call for agent agent_voicesim_seed, so the console starts with content.
• Nothing persists: a restart of the lane that hosts it (haven restart go) empties it.

Tests and load

• Caps: VOICESIM_MAX_CALLS (default 200, oldest dropped) and VOICESIM_MAX_EVENTS_PER_CALL (default 500, the rest counted as droppedEvents).
• Drive the loopback port directly; go test ./services/sims/voicesim covers the protocol.
• The Twilio phone transport is not faked.

From a terminal or agent

--json on every read; non-zero exit on failure; --stack <slug> reads another worktree.

haven sim voice status | list | get <id> | clear