How Arc0 Works

No modifications to your existing tools required—Arc0 observes and relays without changing how your agents work.

Architecture Overview

┌─────────────────────────────────────────────────────────────────┐
│  Your Workstation                                               │
│                                                                 │
│  ┌──────────────┐    ┌──────────────┐    ┌──────────────┐      │
│  │   Arc0 CLI   │───▶│    tmux      │───▶│ Claude Code  │      │
│  │   (daemon)   │◀───│   session    │◀───│ Codex, etc.  │      │
│  └──────┬───────┘    └──────────────┘    └──────────────┘      │
│         │                                                       │
└─────────┼───────────────────────────────────────────────────────┘
          │ WSS (WebSocket Secure)
          │ Arc0 Tunnel
          ▼
┌─────────────────────────────────────────────────────────────────┐
│  Arc0 Apps (iOS / Android / Web)                                │
│                                                                 │
│  ┌──────────────┐    ┌──────────────┐    ┌──────────────┐      │
│  │   Monitor    │    │    Prompt    │    │    Review    │      │
│  │   Progress   │    │   & Direct   │    │   Changes    │      │
│  └──────────────┘    └──────────────┘    └──────────────┘      │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

Components

Arc0 CLI

The CLI runs on your workstation and does three things:

1. Attaches to tmux sessions — It watches your terminal sessions where coding agents run, capturing their output in real-time
2. Runs the Arc0 Daemon — A background process that handles session synchronization, parses agent output, and manages the tunnel connection
3. Streams via Arc0 Tunnel — Establishes a secure WebSocket connection to your phone

Arc0 Tunnel

The tunnel provides secure connectivity between your machine and your phone:

• WSS (WebSocket Secure) — All traffic is encrypted end-to-end
• No port forwarding required — Works behind NAT, firewalls, and corporate networks
• Low latency — Optimized for real-time back-and-forth communication

Arc0 Apps

The Arc0 mobile apps (iOS/Android) and webapp (PWA) receive the stream from your CLI and let you:

• Monitor progress — Watch your agent work in real-time
• Send prompts — Guide your agent with direction and clarification
• Approve plans — Review implementation plans before coding starts
• Track changes — See every file modification as it happens
• Review code — Approve or request changes to diffs

The Flow

1. Start Your Agent

Run your AI coding assistant as you normally would—in a tmux session:

tmux new -s dev
claude  # or codex, gemini, etc.

2. Arc0 CLI Captures the Session

Arc0 CLI automatically detects and attaches to your tmux session:

arc0 start

It captures:

• Agent output and responses
• Questions and prompts from the agent
• File changes and diffs
• Plan proposals and tool usage

3. Real-Time Sync to Your Phone

Everything streams to your phone over WebSocket:

• Instant delivery — See agent activity as it happens
• Bidirectional — Your responses go back just as fast
• Persistent — Connection survives brief network interruptions

4. You Direct, Agent Executes

From your phone, you're in control:

• Approve the agent's plan to proceed
• Send a prompt to adjust direction
• Review a diff and approve or reject
• Monitor progress while you're away

Why tmux?

Arc0 uses tmux for session capture because:

• No CLI modifications — Works with Claude Code, Codex, Gemini CLI as-is
• Session persistence — Your agent keeps running even if you disconnect
• Universal — Works on macOS and Linux out of the box
• Battle-tested — tmux is reliable, fast, and widely used

Security

Your code stays on your machine. Arc0 only streams:

• Agent conversation (prompts and responses)
• File diffs (changes, not full files)
• Session metadata (status, progress)

The tunnel encrypts everything with WSS. No data is stored on Arc0 servers—it's a pass-through connection between your machine and your phone.

See Security for full details.

Next Steps