v0.22.1-nightly.33

Automated nightly build from main (2026-04-04)

v0.22.0

Browser & desktop workflows

Enabled in Experiments -> Agent Browser

• New Browser tab support for live agent-browser sessions, including an address bar, reload control, ready-state display, and streaming updates.
• Better Browser tab signal with clearer Recent Actions and less noise.
• Improved reliability for keyboard delivery, shell-launched browser sessions, and server-mode browser sessions.
• Added workspace-scoped virtual desktops via Portable Desktop.

Agents, SSH, and models

• Added grouped task variants and made task variants easier to discover.
• agent-browser is now available as a built-in skill.
• SSH workspaces can now use host-global skills and agents.
• Added support for GPT-5.4 Mini and GPT-5.4 Nano.

Quality of life

• Consistent recovery of interrupted chats on restart.
• Improved queued-message handling and chat layout stability while sending or resizing the composer.
• Polished immersive review with LoC progress, cross-file navigation, and undo.
• Reduced idle compaction / notification noise and improved startup diagnostics.

v0.21.0

Sub-agents

• New sidebar hierarchy for sub-agents, including connector lines and better expansion for completed runs.
• Active sub-agents animate in the sidebar.
• The sub-agent toggle moved to the kebab menu.
• Double-click now always renames.
• Added support for "Best of N" type sub-agent launches where the parent launch N sub-agents with the same prompt and synthesizes the best path forward

Analytics

• Added a save action for chat analytics results.
• Added a saved analytics panel SQL editor.

Quality of Life

• Better handling of edited messages before stream start.
• Reduced false interruptions by not treating slow stream starts as interruptions.
• Todos are session-scoped now, so they survive stream interruptions better.
  • Completed todo lists are cleared more reliably after final streams.
  • Pinned todo panels now auto-collapse more appropriately.
• Better wide-touch sidebar interactions.
• Mux now surfaces MCP server startup failures instead of failing more silently.
• Fixed some cost display/reset issues around Codex OAuth and forked workspaces.

v0.20.1

What's Changed

• improved cost and tracking management for gpt-5.4 family

Full Changelog: v0.20.0...v0.20.1

v0.20.0

This release updates the gpt and gpt-pro models to GPT 5.4, including support for the additional 1M context.

Also, we've made incremental style improvements across the UI.

v0.19.0

✨ Highlights

• API support for gpt-5.3-codex and added support for gpt-5.3-codex-spark
  • Note: at the time of this release Spark requires the ChatGPT Pro ($200/m) plan
• Analytics page (Cmd+Shift+Y) to provide a convenient look into spend and model performance
• "Auto" agent mode which delegates selection of exec/plan/ask/etc. mode to the agent
• Immersive Review (Shift+I), which provides an IDE-like, full-file review experience
  • We are actively fixing some performance issues with large files, consider this feature a preview of things to come
• Nightly release channel available when clicking the version number in the top left of Mux

Misc.

• Contains many improvements to the mobile experience
• Simplified the Chat Input controls, consolidating help indicators
• Added first-class support for creating creating skills in the Chat with Mux help workspace

v0.18.0

Another polish/fix-oriented release with some notable changes:

• First-class support for Sonnet 4.6 and Gemini 3.1 Pro
  • Sonnet 4.6 has much of the same new features and capabilities as Opus 4.6, including 1M context, max thinking, and effort-based reasoning
  • Available via aliases sonnet and gemini
• Text now streams in more smoothly
• Many improvements to the Orchestrator agent
• Fork improvements
  • Now well-supported for Docker workspaces
  • Available as a quick action in the workspace context menu
  • Removed the name requirement, so /fork [message] works and auto-generates a name
• Title improvements
  • Hit F2 to quickly re-title a chat
  • Hit Shift+F2 to auto-generate a new title
• You can now right-click text in the chat transcript and then click "Quote in input" to quickly address a portion of the response
• Support for dragging and dropping PDFs as input for Opus 4.6

v0.17.0

This release is focused on bug-fixes and polish.

Improvements include:

• Fixed layout flash when bash stream transitions from streaming to static
• Cleaned up the Chat Input area, unlocking ~10px more usable space for chat contents
• When using Opus 4.6 with Mux Gateway, we will automatically retry the compaction with 1m context enabled if the original request fails with context_exceeded
• We added a new flow to "Add Project" to allow for quickly starting from a Git repo

v0.16.2

Hotfix: primarily for fixing a bug where chat history before compaction boundary was included in frontend context calculation, leading to incorrect reporting and premature compaction.

v0.16.1

GPT-5.3-Codex

We’re releasing this off-cycle to make GPT-5.3-Codex broadly available to users. Support is enabled via our new ChatGPT plan settings at Settings → Providers → OpenAI.

As of now, GPT-5.3-Codex ranks #3 on Terminal Bench with a strong showing on the Terminal Bench leaderboard.

Chat Sharing

You can now share a full transcript of your chat via an end-to-end encrypted link.
Right-click the workspace and select “Share transcript.”

Here’s a sample chat.

Misc.

This release includes several additional improvements:

• Workspace chats are now append-only on disk, preserving history prior to compaction.
• In this release, you can view up to one compaction back; full paging support is coming soon (including mux.md sharing).
• The SSH runtime now uses remote worktrees, making new workspaces and forks much faster.
• Skill load errors now appear directly in the workspace’s skill badge.
• mux run now supports sub-agents.
  • Invoke via bun x mux run or npx mux run.