Glossary
Definitions of key terms and concepts used throughout Arc0 documentation, including CLI commands, tunnel connections, and mobile app features.
A
Agent
A coding agent is an AI-powered tool that can write, modify, and execute code based on natural language instructions. Examples include Claude Code, OpenAI Codex CLI, and Google Gemini CLI. Agents run in your terminal and interact with your local development environment.
Arc0 Apps
The iOS, Android, and web applications (PWA) that let you monitor and interact with your coding agents remotely. Arc0 Apps receive the stream from Arc0 CLI and provide a mobile-optimized interface for reviewing diffs, responding to agent questions, and approving plans.
Arc0 CLI
The command-line tool that runs on your development machine. It captures your coding agent sessions via tmux and runs a daemon that manages a secure tunnel connection. The CLI is open source and runs locally—your code never leaves your machine.
Arc0 Daemon
The background process within Arc0 CLI that handles session synchronization and communication. It manages the secure tunnel connection, parses agent output, and relays data between your coding agent and the Arc0 mobile/web apps.
Arc0 Tunnel
The secure WebSocket (WSS) connection between Arc0 CLI and your mobile/web apps. The tunnel encrypts all traffic end-to-end and works behind NAT, firewalls, and corporate networks without requiring port forwarding.
D
Diff
A diff (short for "difference") shows the changes between two versions of code. When your agent modifies files, Arc0 displays the diff so you can review additions (green), deletions (red), and modifications before approving.
Diff Viewer
The mobile-optimized interface in the Arc0 app for reviewing code changes. Designed for readability on smaller screens with syntax highlighting and swipe gestures.
P
Pairing
The process of connecting your development machine (running Arc0 CLI) to your phone (running the Arc0 app). Pairing is done once via QR code and establishes a secure, persistent WebSocket connection through a tunnel.
Push Notification
An alert sent to your phone when your coding agent needs input or proposes a plan. Arc0 uses smart filtering to only notify you when action is required—not for every line of agent output.
S
Session
A session is a single run of your coding agent, from start to finish. Arc0 captures the full session including prompts, responses, code changes, and any questions the agent asks.
Session Feed
The real-time view of your agent's activity in the Arc0 app. Shows what the agent is currently doing, recent output, and pending questions.
T
tmux
A terminal multiplexer that Arc0 uses to capture agent sessions. tmux lets you run terminal sessions that persist in the background—Arc0 CLI attaches to these sessions to stream their output to your phone.
Tunnel
See Arc0 Tunnel.
W
WebSocket
The communication protocol Arc0 uses for real-time, bidirectional communication between your machine and phone. WebSocket enables fast back-and-forth—your prompts reach your agent instantly, and agent output streams to your phone in real-time.
Workstation
Your laptop, desktop computer, or development server where coding agents like Claude Code, Codex, and Gemini CLI run. This is where Arc0 CLI runs to capture agent sessions and establish the connection with your mobile app. The workstation holds your codebase and development environment—your code never leaves it.
WSS
WebSocket Secure—the encrypted version of WebSocket. All Arc0 connections use WSS to ensure your data is protected in transit.
Frequently Asked Questions
Answers to common questions about Arc0 setup, compatibility, security, mobile app features, self-hosting, and coding agent integrations.
How Arc0 Works
Understand the architecture behind Arc0—how the CLI, tunnel, and mobile app work together to connect you with your coding agents.