#cmux 0.64.11: Workspace Groups, Focus & Recently Closed History, Agent Hibernation, Detachable SSH

June 1, 2026

Workspace Groups. Select sidebar workspaces and press ⌘⇧G to gather them under a collapsible header. Each group has an anchor workspace, its own color and icon, and an unread badge on the header. Drag workspaces in and out, reorder inside a group, and control where new workspaces land per group or via cmux.json. A full `cmux workspace-group` CLI namespace creates, colors, moves, focuses, and deletes groups from scripts.

Focus & Recently Closed History. Navigate back and forward through recently focused workspaces and windows straight from the titlebar, with shortcut hints inline. A searchable Recently Closed history pane reopens surfaces you closed, restoring them to their original anchor.

Agent Hibernation. Idle agent sessions hibernate to cut background CPU and memory, then restore on demand with their state intact, so a sidebar full of agents stops competing for resources while you work in one.

Detachable SSH PTY Daemon. Remote SSH sessions now run behind a detachable PTY daemon that keeps the session alive across reconnects, so a dropped network connection no longer kills your remote workspace.

Font Size Controls & Notifications Redesign. The sidebar workspace font size and the workspace tab bar font size (capped at 14pt) are both configurable. The notifications popover was redesigned bigger and more minimal with swipe-to-dismiss, and now uses Hermes hook payloads for richer agent notifications.

Fork Conversation, Browser Mute, Diff Viewer. Fork Conversation moves into the tab right-click menu with configurable destinations, browser tabs gain an audio mute toggle, and `cmux diff` opens a CodeView diff viewer that streams large git diffs before full render.

Added

Workspace groups: select sidebar workspaces and press ⌘⇧G to group them under a collapsible header, with an anchor workspace, drag-to-group, in-group reorder, per-group color and icon, unread badges on the header, and a Delete Group action that closes all members (#4815)
cmux workspace-group CLI namespace to create, remove, set-color, set-icon, move, and focus groups, with new-workspace placement configurable per group and via cmux.json (#5018)
Focus history and Recently Closed history: navigate back and forward through recently focused workspaces and windows from the titlebar, and reopen recently closed surfaces from a searchable history pane (#4160)
Agent Hibernation pauses idle agent sessions and restores them on demand to cut background resource use (#4165)
Detachable SSH PTY daemon keeps remote sessions alive across reconnects so SSH workspaces survive a dropped connection (#4807)
Configurable sidebar workspace font size, plus a workspace tab bar font size control capped at 14pt (#4798)
Browser tab audio mute toggle in the tab right-click menu, kept in sync with WebKit playback state (#4911)
Fork Conversation action in the tab right-click menu, with configurable fork destinations (#4888, #4986 -- thanks @lawrence703!)
Xcode-style project visualizer pane (#4996)
cmux diff command opens a CodeView diff viewer, with large git diffs streamed into the viewer before full render (#4451, #5016)
Send Ctrl-F to Terminal passthrough action to force-stop Claude Code agents (#5011)
Native Kiro CLI hook integration with notifications, task manager attribution, and session restore (#4831)
Default terminal registration so the system terminal preference resolves to cmux (#4935)
Configurable browser search providers (#4849)
Terminal textbox input with beta TextBox defaults settings (#4333, #4773)
Viewport-aware workspace path display truncates sidebar paths to fit the available width (#3730) -- thanks @gonzaloserrano!
Wrap long workspace titles in the sidebar instead of truncating (#4848)
Open cmd-clicked Markdown paths in the Markdown viewer (#4864)
Beta Features toggle gates the in-progress extension sidebar UI (#5092)

Changed

Notifications popover redesigned: bigger, minimal layout with swipe-to-dismiss (#4778)
Use Hermes hook payloads for richer agent notifications (#4851)
Settings is now a top-level peer window instead of a floating child window (#5081)
Launch restored agent sessions through their saved startup commands (#4777)
Reduce browser WebView input latency (#4863)
Make the workspace sidebar lazy with @Observable drag state and batch sidebar actions for faster reorders on large sidebars (#4736, #4865)
Make session index backfill linear so large session histories load faster (#4868)
Resolve TypeScript .ts files as text previews instead of routing them through QuickLook media (#4924)
Forward CLI subcommands from the GUI binary to the bundled CLI (#4679) -- thanks @tiffanysun1!

Fixed

Fix File Preview hang when drag-selecting large files (#4962)
Fix the File Preview Open With menu (#4932)
Stop stale closed-browser snapshots from reappearing in unrelated workspaces (#4961)
Fix zsh hook errors when the job table is saturated (#4959)
Fix bash job notification spam (#4934)
Fix Claude hooks-disabled environment passthrough (#4418)
Fix NSFileHandle process pipe read crashes (#4800)
Fix cmux terminal environment injection (#4728)
Recognize Eternal Terminal for remote file drops (#4712)
Fix Vault resume for non-ASCII paths (#4683)
Fix Markdown files with trailing punctuation being detected as URLs (#4594) -- thanks @jasonko!
Fix the Reload Configuration menu action (#4534)
Fix OMO tmux compatibility session ids (#4468)
Fix equalize split span weighting so 3+ pane rows distribute evenly (#4787)
Fix matched sidebar terminal background (#4780)
Fix restore-previous-launch crash and preserve current work on restore (#4982)
Fix agent resume when the saved cwd was deleted (#4859)
Fix hidden Settings window burning CPU during Codex output (#4661)
Fix embedded Ghostty split theme resolution so split panes inherit the active theme (#4795)
Fix titlebar controls intercepting window drags and right-sidebar button clicks (#5005, #5102)
Fix split zoom not clearing when the maximized tab is closed (#5076)
Fix spurious "Terminal needs approval" prompts from the Hermes pre-tool-call hook (#5010)
Fix Hermes session restore so a per-turn session-end is treated as a turn boundary, not a teardown (#5009)
Fix the JSONC comment skipper for CRLF line endings (#4869)
Fix Bonsplit tab indicator drift (#4873)
Open bare relative path arguments externally without requiring socket access (#4812)
Keep Cmd-Tab app switching off the session snapshot path (#4613)
Restore the sidebar minimum width and keep the titlebar stable at minimum width (#5062, #5089)