ReplyFast

Signal messaging library for Python using Presage (Rust).

Installation

uv pip install replyfast

# With optional dependencies
uv pip install replyfast[scheduler]  # For cron scheduling
uv pip install replyfast[qrcode]     # For QR code display
uv pip install replyfast[all]        # Everything

Contents

• Quick Start
• API Reference
  • SignalClient
  • Message
• Signal Handling
• Scheduler
  • Scheduler with Message Receiving
  • Scheduler Only
  • Cron Expression Format
  • Decorator Syntax
• Examples
• Requirements

Quick Start

from replyfast import SignalClient

# Create client
client = SignalClient("./data")

# Link as secondary device (first time only)
def on_url(url):
    print(f"Scan this QR code with Signal app: {url}")

client.link_device_sync("MyDevice", on_url)

# Send a message
client.send_message_sync("recipient-uuid", "Hello!")

# Or find contact by phone/name first
contact = client.find_contact_by_phone_sync("+1234567890")
if contact:
    client.send_message_sync(contact.uuid, "Hello!")

# Receive messages
def on_message(msg):
    if msg.is_queue_empty:
        print("Initial sync complete")
        return True

    print(f"From: {msg.sender}, Body: {msg.body}")
    return True  # Return True to continue, False to stop

client.receive_messages_sync(on_message)

API Reference

SignalClient

Message

Signal Handling

The library handles SIGINT (Ctrl+C) cleanly. When you press Ctrl+C during receive_messages_sync(), it will:

1. Stop the receive loop gracefully
2. Raise KeyboardInterrupt in Python
3. Allow cleanup code to run

try:
    client.receive_messages_sync(on_message)
except KeyboardInterrupt:
    pass  # Clean exit

print("Stopped")

Scheduler

Send messages at scheduled times using cron syntax.

Scheduler with Message Receiving

When running a bot that both receives messages and runs scheduled tasks, start the scheduler after the initial sync is complete (indicated by is_queue_empty):

import time
from replyfast import SignalClient, Scheduler

client = SignalClient("./data")
scheduler = Scheduler()

# Define scheduled task
def periodic_task():
    client.send_message_sync("recipient-uuid", "Scheduled message!")

# Register jobs before starting
scheduler.register(
    "*/5 * * * *",  # Every 5 minutes
    periodic_task,
    name="periodic-task"
)

# Message handler that starts scheduler after sync
def on_message(msg):
    # Start scheduler once initial sync is complete
    if msg.is_queue_empty:
        print("Ready to receive messages")
        scheduler.start()  # Start scheduler in background
        return True

    if msg.body:
        print(f"From: {msg.sender}: {msg.body}")
        # Handle commands here

    return True

# Run with reconnection loop for long-running bots
reconnect_delay = 5

while True:
    try:
        client.receive_messages_sync(on_message)
        break  # Normal exit
    except KeyboardInterrupt:
        break  # Ctrl+C
    except Exception as e:
        print(f"Connection error: {e}")
        print(f"Reconnecting in {reconnect_delay}s...")
        time.sleep(reconnect_delay)
        reconnect_delay = min(reconnect_delay * 2, 300)  # Max 5 min

scheduler.stop()
print("Stopped")

Scheduler Only (No Message Receiving)

from replyfast import SignalClient, Scheduler

client = SignalClient("./data")
scheduler = Scheduler()

def send_greeting():
    contact = client.find_contact_by_phone_sync("+1234567890")
    if contact:
        client.send_message_sync(contact.uuid, "Good morning!")

scheduler.register(
    "0 9 * * *",  # cron: minute hour day month weekday
    send_greeting,
    name="morning-greeting"
)

# Run scheduler (blocking)
scheduler.run()

# Or run in background
scheduler.start()
# ... do other things ...
scheduler.stop()

Cron Expression Format

┌───────────── minute (0-59)
│ ┌───────────── hour (0-23)
│ │ ┌───────────── day of month (1-31)
│ │ │ ┌───────────── month (1-12)
│ │ │ │ ┌───────────── day of week (0-6, 0=Sunday)
│ │ │ │ │
* * * * *

Examples:

• */5 * * * * - Every 5 minutes
• 0 9 * * * - Every day at 9:00 AM
• 0 9 * * 1-5 - Weekdays at 9:00 AM
• 30 */2 * * * - Every 2 hours at minute 30

Decorator Syntax

from replyfast import schedule, get_scheduler

@schedule("0 9 * * *")
def daily_task():
    print("Runs every day at 9 AM")

get_scheduler().start()

Examples

The examples/ directory contains complete working examples:

example.py

Basic usage showing how to list contacts, groups, and receive messages with proper signal handling:

python examples/example.py

Demonstrates:

• Checking registration status
• Getting account info with whoami_sync()
• Listing contacts and groups
• Receiving messages with callback
• Handling typing indicators and read receipts
• Clean Ctrl+C shutdown

demo_bot.py

A bot that sends system stats on a schedule while also responding to commands:

DEMO_RECIPIENT=<uuid> python examples/demo_bot.py

Demonstrates:

• Scheduler with message receiving (starts after is_queue_empty)
• Multiple scheduled jobs (df -h every 5 min, free -m every hour)
• Interactive commands (ping, df, free, help)
• Reconnection loop with exponential backoff
• Proper cleanup on shutdown

Requirements

• Python 3.10+
• Rust toolchain (for building from source)

License

AGPL-3.0-or-later