ReachTether

ReachTether is a .NET codebase for building voice-first Reachy Mini robot applications.

What Is In This Repo

• dotNet/ReachTether.Robot: main robot runtime (hosted services, VAD, OpenAI conversation, speech playback, motion orchestration)
• dotNet/ReachTether.Audio: audio primitives (frames, format helpers, WAV conversion)
• dotNet/ReachTether.Audio.Alsa: local ALSA audio session and capture/playback device integration
• dotNet/ReachTether.WebRtc: WebRTC session and signaling utilities
• dotNet/ReachyMini.Sdk: typed Reachy Mini SDK client library
• dotNet/ReachTether.slnx: solution file for the active projects above
• Docs/: architecture notes, deployment notes, and design research

Runtime Overview

ReachTether.Robot is a long-running host process that:

1. Connects to Reachy Mini over HTTP (ReachyMini:BaseUrl).
2. Connects to local audio devices via ALSA.
3. Captures speech input with VAD.
4. Sends transcription/chat/speech requests to OpenAI.
5. Streams/plays audio responses.
6. Applies motion and talking gestures while interacting.

Voice pipeline mode is controlled by OpenAI:VoicePipeline:

• auto: choose realtime for realtime-style models, otherwise legacy turn-based flow.
• realtime: force realtime pipeline.
• legacy: force turn-based STT -> chat -> TTS pipeline.

Prerequisites

• .NET SDK 9.0+ (main projects target net9.0)
• Network access to Reachy Mini daemon endpoint (for example http://reachy-mini.local:8000)
• OpenAI API key exposed as OPENAI_API_KEY
• Linux environment with ALSA devices for robot audio runtime

Notes:

• ReachyMini.Sdk multi-targets net8.0, net9.0, and net10.0.
• OPENAI_API_KEY is read from environment or .env; it is not read from appsettings*.json.

Build

From repository root:

dotnet restore dotNet/ReachTether.slnx
dotnet build dotNet/ReachTether.slnx -c Release

Run ReachTether.Robot

From repository root:

1. Create dotNet/ReachTether.Robot/.env:

OPENAI_API_KEY=your_openai_api_key_here

2. (Optional but recommended) Create dotNet/ReachTether.Robot/appsettings.local.json for local overrides:

{
  "ReachyMini": {
    "BaseUrl": "http://reachy-mini.local:8000"
  },
  "Audio": {
    "CaptureDevice": "reachymini_audio_src",
    "PlaybackDevice": "reachymini_audio_sink",
    "Channels": 2
  },
  "OpenAI": {
    "VoicePipeline": "auto",
    "ChatModel": "gpt-realtime-mini",
    "TranscriptionModel": "gpt-4o-mini-transcribe",
    "SpeechModel": "gpt-4o-mini-tts",
    "SpeechVoice": "alloy",
    "TranscriptionLanguage": "en",
    "Realtime": {
      "Model": "gpt-realtime-mini",
      "ResponseTimeoutMs": 45000,
      "OutputSampleRateHz": 24000
    }
  }
}

3. Run:

dotnet run --project dotNet/ReachTether.Robot/ReachTether.Robot.csproj

Configuration Keys

Primary keys consumed by ReachTether.Robot:

Key	Purpose
ReachyMini:BaseUrl	Reachy daemon base URL
Audio:CaptureDevice	ALSA capture device name
Audio:PlaybackDevice	ALSA playback device name
Audio:Channels	Audio channel count (1 or 2)
OpenAI:VoicePipeline	auto, realtime, or legacy
OpenAI:ChatModel	Chat/realtime selection model
OpenAI:TranscriptionModel	STT model for legacy pipeline
OpenAI:SpeechModel	TTS model
OpenAI:SpeechVoice	Voice (alloy, echo, fable, onyx, nova, shimmer)
OpenAI:TranscriptionLanguage	STT language hint
OpenAI:Realtime:*	Realtime model and timeout/sample-rate controls
VAD:*	Voice activity detection thresholds/timing
Motion:*	Gesture loop behavior and safety limits
Personality:CatalogPath	Personality JSON catalog path
Personality:Default	Default personality id

Publish and Deploy (Reachy Mini linux-arm64)

From repository root:

dotnet publish dotNet/ReachTether.Robot/ReachTether.Robot.csproj \
  -c Release -r linux-arm64 --self-contained false \
  -o out/reachrobot

Copy artifacts to robot:

scp -r out/reachrobot/. pollen@reachy-mini.local:/home/pollen/reachrobot/

Run on robot:

ssh pollen@reachy-mini.local
cd /home/pollen/reachrobot
dotnet ReachTether.Robot.dll

Troubleshooting

• OPENAI_API_KEY not found: ensure .env exists in working directory or set env var before launch.
• Reachy connection failure: verify ReachyMini:BaseUrl and that daemon is reachable.
• ALSA device errors: confirm capture/playback device names on target host.
• Unexpected pipeline mode: set OpenAI:VoicePipeline explicitly to realtime or legacy.

Additional Docs

• Docs/ReachTether-on-reachy-mini.md
• Docs/reachtether-evolution-findings.md
• Docs/architectural-findings-and-roadmap.md
• Docs/realtime-immediate-playback-sketch.md
• Docs/deploying.md (contains older notes; prefer commands in this README for current runtime)