Signal Integration

Complete Signal messenger integration with security-first contact management.

Feature Overview

Text & voice messaging — Send and receive text messages, voice notes, images, and attachments
Role-based permissions — Three-tier contact system (owner/trusted/untrusted) controls who can instruct your agent to execute commands, modify files, or access private information
New contact triage — Unknown senders are flagged for owner approval before the agent engages; prevents prompt injection via unsolicited messages
Voice transcription — Incoming voice messages transcribed via Whisper (or any STT engine) for processing
Voice replies — Generate spoken responses via TTS and send as audio attachments
Conversation history — Per-contact message logs with timestamps for context continuity
Typing indicators — Shows "typing..." in the recipient's Signal app before sending
Read & viewed receipts — Marks messages as read; sends "viewed" receipt for voice messages
UUID contact support — Handles both phone number and UUID-based Signal contacts
Instant wake — Triggers OpenClaw's /hooks/wake API on new messages for immediate response (no waiting for next heartbeat)
Auto-logging — All sent and received messages logged to conversation files

Prerequisites

signal-cli (v0.13.x+): Java-based Signal client — github.com/AsamK/signal-cli
ffmpeg: Audio format conversion
A phone number: For Signal registration (can be a VoIP number)
OpenClaw hooks: For instant wake-on-message (optional but recommended)

Optional (for voice messages)

Whisper (or whisper.cpp): Speech-to-text transcription
TTS engine (Coqui, Piper, or OpenClaw's built-in tts tool): Text-to-speech for voice replies

Setup

1. Install signal-cli

# Download latest release
SIGNAL_CLI_VERSION="0.13.12"
curl -L "https://github.com/AsamK/signal-cli/releases/download/v${SIGNAL_CLI_VERSION}/signal-cli-${SIGNAL_CLI_VERSION}-Linux.tar.gz" | tar xz
sudo mv signal-cli-${SIGNAL_CLI_VERSION}/bin/signal-cli /usr/local/bin/
sudo mv signal-cli-${SIGNAL_CLI_VERSION}/lib /usr/local/lib/signal-cli

# Or install to user directory
mv signal-cli-${SIGNAL_CLI_VERSION} ~/.local/share/signal-cli-install
ln -s ~/.local/share/signal-cli-install/bin/signal-cli ~/.local/bin/signal-cli

Requires Java 21+: sudo apt install openjdk-21-jre-headless

2. Register a number

# Register with SMS verification
signal-cli -a +YOUR_NUMBER register

# Enter the verification code
signal-cli -a +YOUR_NUMBER verify CODE

# Set your profile name
signal-cli -a +YOUR_NUMBER updateProfile --given-name "YourName" --family-name "Bot"

3. Configure the scripts

Edit scripts/signal-poll.sh and scripts/signal-send.sh:

Set SIGNAL_NUMBER to your registered number
Set SIGNAL_CLI to your signal-cli binary path
Set STATE_DIR to your preferred state directory (default: ~/.signal-state)
Add known contacts to ALLOWLIST and CONTACTS in signal-poll.sh

4. Set up cron polling

# Poll every minute
crontab -e
# Add: * * * * * /path/to/scripts/signal-poll.sh

5. Configure OpenClaw wake hook (recommended)

Add to your openclaw.json config:

{
  "hooks": {
    "wake": {
      "enabled": true,
      "token": "your-secret-token"
    }
  }
}

Then set the same token in signal-poll.sh (WAKE_TOKEN variable) and the OpenClaw URL (WAKE_URL).

Architecture

signal-cli ←→ signal-poll.sh (cron every 1min)
                  ├── Parses text + attachments
                  ├── Logs to conversations/<sender>.log
                  ├── Writes pending_wakes file
                  └── POSTs to OpenClaw /hooks/wake API
                  
Agent (heartbeat/wake)
  ├── Reads pending_wakes
  ├── Reads conversation history for context
  ├── Transcribes voice messages (Whisper)
  ├── Generates reply (text or voice)
  └── Sends via signal-send.sh

Sending Messages

# Text message
scripts/signal-send.sh +1234567890 "Hello!"

# With attachment
signal-cli -a +YOUR_NUMBER send +RECIPIENT -m "Check this out" -a /path/to/file

# Voice message (generate TTS then send as attachment)
# 1. Generate audio (use your TTS engine)
# 2. Convert to m4a: ffmpeg -i voice.wav -c:a aac -b:a 64k voice.m4a
# 3. Send: signal-cli -a +YOUR_NUMBER send +RECIPIENT -m "" -a voice.m4a

Receiving Messages

The poll script handles receiving automatically. In your HEARTBEAT.md, add:

### Signal Messages (check first!)
cat /path/to/.signal-state/pending_wakes 2>/dev/null

When processing a wake:

Read pending_wakes for new message summary
Read conversations/<sender>.log for full context
For voice messages: transcribe the attachment path with Whisper
Respond via signal-send.sh or voice attachment
Clear: > /path/to/.signal-state/pending_wakes

Voice Message Handling

Transcribing incoming voice messages

# Convert to WAV for Whisper
ffmpeg -i /path/to/attachment.m4a -ar 16000 -ac 1 -c:a pcm_s16le /tmp/audio.wav -y

# Transcribe (whisper.cpp server example)
curl -s http://127.0.0.1:8080/inference -F "file=@/tmp/audio.wav" -F "language=en"

# Or use OpenAI Whisper, faster-whisper, etc.

Sending voice replies

# 1. Generate speech (example with a local TTS server)
curl -X POST http://127.0.0.1:5002/tts \
  -H "Content-Type: application/json" \
  -d '{"text": "Your message here", "language": "en"}' \
  -o /tmp/voice.wav

# 2. Convert to m4a for Signal
ffmpeg -i /tmp/voice.wav -c:a aac -b:a 64k /tmp/voice.m4a -y

# 3. Send as attachment
signal-cli -a +YOUR_NUMBER send +RECIPIENT -m "" -a /tmp/voice.m4a

Contact Management

New contacts (UUID-based)

When someone new messages you, signal-cli may show them as a UUID (no phone number). The poll script handles both phone numbers and UUIDs.

# Accept a message request
signal-cli -a +YOUR_NUMBER sendMessageRequestResponse --type accept UUID_OR_NUMBER

# List all known identities
signal-cli -a +YOUR_NUMBER listIdentities

Triage workflow

Unknown senders are logged to .signal-state/triage.log and flagged in pending_wakes with ⚠️ NEW CONTACT. The agent should:

Notify the owner about the new contact
Wait for approval before engaging
Add approved contacts to ALLOWLIST in signal-poll.sh

Typing Indicators & Read Receipts

The send script automatically shows a typing indicator before sending. The poll script sends read receipts and "viewed" receipts for voice messages.

File Reference

scripts/signal-poll.sh — Cron-based message receiver with wake integration
scripts/signal-send.sh — Send wrapper with typing indicator and conversation logging
references/troubleshooting.md — Common issues and fixes