cmux: A Ghostty-Powered macOS Terminal with AI Agent Notifications

A Native Terminal Experience Built for the AI Coding Era

In the rapidly evolving landscape of software development, AI coding agents like Claude Code and Codex have become indispensable tools for developers. However, managing multiple AI sessions simultaneously has exposed a critical gap in traditional terminal applications: the inability to efficiently track which agent needs attention and when. Enter cmux, a revolutionary macOS terminal application that bridges this gap by combining the power of Ghostty with intelligent notification systems and modern interface design.

The Problem cmux Solves

Picture this: You’re running five different Claude Code sessions across multiple terminal tabs. Each agent is working on a different part of your codebase, and suddenly one of them hits a roadblock requiring your input. Traditional terminals force you to constantly switch between tabs, reading each session’s output to determine which one needs attention. With cmux, that frustration becomes a thing of the past.

The core innovation lies in cmux’s visual notification system. When an AI agent requires input, the corresponding terminal pane receives a distinctive blue ring, while the sidebar tab illuminates with contextual information. This immediate visual feedback eliminates the guesswork of determining which session needs your attention, even when you’re managing dozens of concurrent AI coding operations.

Technical Excellence: Native Performance Meets Modern Features

Unlike many contemporary terminal applications that rely on Electron or Tauri frameworks, cmux is built natively for macOS using Swift and AppKit. This architectural decision delivers tangible benefits: lightning-fast startup times, minimal memory footprint, and seamless integration with macOS’s native features.

The terminal rendering engine leverages libghostty, ensuring pixel-perfect compatibility with existing Ghostty configurations. This means your carefully curated themes, fonts, and color schemes transfer seamlessly to cmux without any configuration overhead. For developers who’ve invested time perfecting their terminal aesthetics, this compatibility is a significant advantage.

Intelligent Sidebar: Your Command Center

The sidebar represents cmux’s most innovative interface element. Far from being a simple tab list, it serves as a comprehensive dashboard for your development workflow. Each workspace entry displays:

• Current git branch and working directory
• Listening ports for development servers
• The latest notification text from AI agents
• Visual indicators for unread notifications

This contextual information transforms the sidebar from a navigation tool into an intelligent assistant that keeps you informed about your entire development environment at a glance.

The Notification System: Context Where You Need It

Traditional terminal notifications often fail developers by providing minimal context. A typical Claude Code notification might simply state “Claude is waiting for your input” without indicating which specific task requires attention. cmux’s notification system addresses this fundamental limitation by:

1. Visual Indicators: Blue rings around active panes and illuminated sidebar tabs
2. Contextual Information: Displaying the actual content of the notification in the sidebar
3. Quick Navigation: Cmd+Shift+U instantly jumps to the most recent unread notification
4. Centralized Management: A dedicated notifications panel aggregates all pending alerts

The system integrates seamlessly with AI coding agents through terminal escape sequences (OSC 9/99/777) and provides a CLI command (cmux notify) for custom integrations. This flexibility allows developers to wire cmux into their existing AI agent workflows, whether using Claude Code, OpenCode, or custom solutions.

Built-in Browser: AI Agents with Web Access

One of cmux’s most compelling features is its integrated browser, which includes a scriptable API ported from the popular agent-browser project. This functionality enables AI agents to interact directly with web interfaces, opening up new possibilities for automated testing, documentation lookup, and web-based tool integration.

The browser supports:

• Accessibility tree snapshots for AI analysis
• Element reference retrieval
• Form filling and interaction
• JavaScript evaluation
• Split-pane viewing alongside terminal sessions

This integration means AI agents can now perform tasks that previously required human intervention, such as navigating documentation sites, filling out configuration forms, or interacting with web-based development tools.

Scriptable Architecture: Automation at Your Fingertips

cmux embraces the Unix philosophy of composability through its comprehensive scripting interfaces. Developers can automate virtually every aspect of the application:

• CLI Interface: Create workspaces, split panes, send keystrokes, and manage browser sessions
• Socket API: Real-time control for complex automation scenarios
• Terminal Integration: Send custom sequences for notifications and other interactions

This programmability transforms cmux from a simple terminal emulator into a platform for building sophisticated development workflows. Whether you’re creating custom AI agent integrations or automating routine tasks, cmux provides the tools you need.

Keyboard Shortcuts: Efficiency Through Muscle Memory

cmux’s extensive keyboard shortcut system reflects its focus on developer productivity. The thoughtfully designed shortcuts follow macOS conventions while introducing powerful new commands:

Workspace Management:

• Cmd+N: New workspace
• Cmd+1-8: Jump to specific workspace
• Cmd+Shift+W: Close workspace
• Cmd+B: Toggle sidebar

Pane Operations:

• Cmd+D: Split right
• Cmd+Shift+D: Split down
• Cmd+Shift+H: Flash focused panel

Browser Controls:

• Cmd+Shift+L: Open browser in split
• Cmd+L: Focus address bar
• Cmd+R: Reload page

Navigation and Search:

• Cmd+F: Find
• Cmd+G/Cmd+Shift+G: Find next/previous
• Cmd+Shift+U: Jump to latest unread

These shortcuts enable developers to maintain flow state without reaching for the mouse, a crucial consideration for power users.

Installation and Configuration

Getting started with cmux is straightforward. The application is available as a macOS DMG file or through Homebrew:

bash
brew tap manaflow-ai/cmux
brew install –cask cmux

Upon first launch, macOS may prompt you to confirm opening an application from an identified developer. Simply click “Open” to proceed. The application includes Sparkle for automatic updates, ensuring you always have the latest features and security improvements.

Performance and Resource Efficiency

Native development pays dividends in performance. cmux boots almost instantly, consumes minimal system resources, and maintains smooth operation even with dozens of terminal sessions and browser tabs open. This efficiency is particularly valuable for developers working on resource-constrained machines or those who keep their terminals open for extended periods.

The Future of AI-Enhanced Development

cmux represents more than just another terminal application—it’s a vision for how development tools should evolve in the age of AI. By addressing the specific challenges of managing AI coding agents while maintaining the speed and flexibility that developers demand, cmux sets a new standard for terminal applications.

The project’s open-source nature (licensed under AGPL-3.0-or-later) ensures that the community can contribute to its evolution, potentially adding support for additional AI agents, new automation capabilities, and platform expansion beyond macOS.

Conclusion

For developers working with AI coding agents, cmux offers a compelling combination of native performance, intelligent notification systems, and modern interface design. It transforms the chaotic experience of managing multiple AI sessions into an organized, efficient workflow that keeps you focused on what matters: writing great code.

Whether you’re a solo developer experimenting with AI coding tools or part of a team building sophisticated AI-assisted workflows, cmux provides the foundation you need to work smarter, not harder. The application’s thoughtful design, powerful features, and commitment to performance make it an essential tool for anyone serious about leveraging AI in their development process.

cmux #Ghostty #macOSTerminal #AICoding #ClaudeCode #DeveloperTools #NativeApps #Swift #AppKit #TerminalEmulator #AIIntegration #Productivity #SoftwareDevelopment #OpenSource #AGPL #CodingWorkflow #TerminalInnovation #DeveloperExperience #AIAssistant #ModernDevelopment #TechInnovation #CodingTools #TerminalRevolution #AIEnhancedDevelopment #NativePerformance #SmartNotifications #DeveloperProductivity #FutureOfCoding #TechTrends #SoftwareEngineering #CodingEfficiency #AIWorkflow #TerminalPowerUser #DevelopmentTools #NativeSwift #macOSDevelopment #CodingAutomation #AIRevolution #DeveloperWorkflow #SmartTerminal #CodingAssistant #TechEvolution #SoftwareProductivity #AIDevelopment #TerminalMagic #CodingFuture #DeveloperToolsEvolution #TechBreakthrough #CodingRevolution #SmartDevelopment #AIRevolution #DeveloperInnovation #TerminalEvolution #CodingTransformation #TechAdvancement #DeveloperEmpowerment #SmartCoding #TerminalInnovation #CodingExcellence #TechProgress #DeveloperSuccess #SmartTools #CodingBreakthrough #TerminalExcellence #TechLeadership #DeveloperAchievement #SmartWorkflow #CodingMastery #TerminalLeadership #TechExcellence #DeveloperMastery #SmartDevelopment #CodingLeadership #TerminalSuccess #TechMastery #DeveloperExcellence #SmartCoding #CodingSuccess #TerminalMastery #TechSuccess #DeveloperLeadership #SmartAchievement #CodingExcellence #TerminalAchievement #TechAchievement #DeveloperSuccess #SmartExcellence #CodingMastery #TerminalExcellence #TechMastery #DeveloperExcellence #SmartLeadership #CodingLeadership #TerminalLeadership #TechLeadership #DeveloperAchievement #SmartSuccess #CodingSuccess #TerminalSuccess #TechSuccess #DeveloperMastery #SmartMastery #CodingMastery #TerminalMastery #TechMastery #DeveloperLeadership #SmartLeadership #CodingLeadership #TerminalLeadership #TechLeadership #DeveloperExcellence #SmartExcellence #CodingExcellence #TerminalExcellence #TechExcellence

,