#cmux 0.64.17: Global Font Magnification, Remote tmux Mirroring, Diff Viewer Branch Picker

June 23, 2026

Global Font Magnification. Scale the entire cmux interface up or down with a single magnification control, not just the terminal font.

Remote tmux Mirroring (Beta). Mirror a remote tmux session over SSH using -CC control mode, so remote windows show up as native cmux tabs that stay in sync with renames and reorders.

Browser and Diff Viewer Polish. Browser panes get a Chrome-style audio-playing indicator and a hard-refresh shortcut. The diff viewer adds a searchable, uncapped branch-base picker with smart defaults and a toolbar that never overlaps at small widths.

Stability and Performance. Fixes for a sidebar lag regression, a vertical-sidebar tab-switch crash, a ~100% CPU re-render loop on bundled extension sidebars, blank SF Symbol controls on macOS 27, terminal content duplication on resize, and quit hangs from analytics flushing.

Added

Remote tmux mirroring over SSH using -CC control mode, in beta (#5553) -- thanks @robertnisipeanu!
Global font magnification to scale the whole interface (#6554)
Right-sidebar custom sidebar tabs (#6430)
Chrome-style audio-playing indicator on browser panes (#6517)
Browser hard-refresh shortcut (#6256)
Clear Screen (Keep Scrollback) command, bound to Cmd+Shift+K (#6139)
Configurable terminal scroll-speed multiplier via terminal.scrollSpeed (#5671) -- thanks @RubiconPerform!
Open the selected file from the keyboard in the file explorer (#6001)
One-step grouped workspace creation (#6657)
Searchable, uncapped diff viewer branch-base picker with smart defaults (#6484) -- thanks @azooz2003-bit!
Mark workspaces read/unread and clear notifications from the workspace group menu (#6535) -- thanks @azooz2003-bit!
Profiling capture action with a live progress window (#6433, #6440)
cmux remotes CLI to manage device-registry routes (#6096)
Flag "Needs input" for blocked AskUserQuestion and ExitPlanMode prompts under --dangerously-skip-permissions (#6608)
iOS (beta): on-device voice dictation in the composer (#6197)
iOS (beta): image attachments in the composer (#6102)
iOS (beta): Return key on the terminal accessory bar (#6101)
iOS (beta): mark workspaces read/unread from the terminal menu, with an unread-count badge on the back button (#6362, #6350)

Changed

Terminal and browser surface tabs hug their content instead of stretching to a fixed width (#6653)
Prioritize full command-palette title matches over partial ones (#6498)
Reduce UI lag from Settings, sidebar, git, and browser churn (#6260) -- thanks @azooz2003-bit!
Evict hidden browser WebViews under memory pressure and defer restored WebViews until visible (#6585, #6508)
Gate idle pollers to the active workspace (#6583)
Diff viewer toolbar stays responsive and never overlaps at small widths (#6550) -- thanks @azooz2003-bit!
Allow .m4r files as notification sounds (#6635)
iOS (beta): collapse workspace folders per device (#6666)

Fixed

Fix a sidebar lag regression from v0.64.16 by cutting per-row font-modifier and pin-state work (#6613)
Fix the Codex sidebar status lifecycle and stale Claude notification sidebar status (#6609, #6473)
Fix sidebar tab selection highlight timing (#6627)
Fix Cmd+T opening in home after an agent-resume session restore (#6621)
Fix explicit surface routing for read-screen and send (#6605)
Fix stale surface-to-panel rebinding and stale agent-resume executable paths (#6581, #6582)
Fix terminal input after a window key restore (#6518)
Fix the Cmd+grave show/hide global hotkey (#6477)
Fix vim copy-mode cursor, V/Y selection, and pasteboard (#6221)
Fix copy-on-select parity with Ghostty (#6200)
Fix the crash-diagnostic window restore (#6596)
Fix a tab-switch crash in the vertical sidebar (#6340)
Fix a ~100% CPU re-render loop when selecting a bundled extension sidebar (#6341)
Fix blank SF Symbol controls on macOS 27 (#6396)
Fix the audio indicator audibility signal (#6566)
Fix browser download trigger parity (#6258)
Recover Settings opened from offscreen frames, and stop a closed Settings window from reappearing (#5806, #6193)
Fix title-churn beachball in transcript adoption and sidebar rows (#6460)
Restore the pane header title after a terminal restart (#6333)
Recover a blank Markdown viewer pane after dragging it to another column (#6331)
Vault sidebar always offers "Show more" so capped folder sections stay reachable (#6327)
Fix the working directory after session-restore resume for Claude and other agents (#6458, #6205)
Fix Claude Code 2.1.183 agent-team teammates opening split panes again (#6499)
Preserve Claude Teams restore flags (#6242)
Fix right-sidebar surface shortcut spam routing (#6472)
Fix Dia browser import profile detection (#6478)
Fix zsh aliases after the agent return shell (#6515)
Fix settings search for auto-naming and broaden fuzzy settings-search matching (#6201, #6196)
Fix terminal focus retry after a tiny responder handoff (#6359)
Avoid DevTools teardown during redock (#6559)
Fix hidden popover relayout and reduce hit-test CPU during SwiftUI updates and pointer movement (#6589, #6592)
Cache the settings search index per runtime (#6591)
Move the open-diff baseline lookup off the main thread (#6497)
Fix the macOS notification fallback identity (#6000)
Fix a remote PTY restore probe reply leak (#6070)
Fix OpenCode bunfs worker autoresume and OpenCode resume after a TUI-settings capture (#6680, #6397)
Fix notification jump-focus for nested tabs (#6416)
Remove a sidebar rows measurement that re-livelocked layout at scale (#6188)
Prevent quit hangs from analytics flushing (#6232, #6417) -- thanks @azooz2003-bit!
Reduce Sentry CLI broken-pipe crashes and hangs (#6254) -- thanks @azooz2003-bit!
Release closed macOS helper windows (#6368) -- thanks @azooz2003-bit!
Fix canvas tab hover hit-testing, focus canvas panes from terminal body clicks, and fix canvas zoom-animation snap at low zoom (#6555, #6456, #6538) -- thanks @azooz2003-bit!
Avoid nested quit-confirmation modal loops (#6461) -- thanks @azooz2003-bit!
Reduce redundant panel title update work (#6552) -- thanks @Eridanus117!
Fix a QuickLook preview crash on a deactivated QLPreviewView (#6402) -- thanks @thiveeiyan!
Fix terminal content duplication on window resize (#6386) -- thanks @mvanhorn!
Stop the main window drifting down on sleep/wake (#6305) -- thanks @sergej-koscejev!
Fix stale cmux ssh pane resize by reconciling remote PTY size after arming SIGWINCH, and fix resize with SSH ControlMaster (#5989, #6432) -- thanks @kylejcaron!
Sync remote tmux session renames to the mirror workspace title, and fix session discovery under a non-UTF-8 remote locale (#6602, #6568) -- thanks @mxschmitt!
Fix the cmux ssh-tmux socket path being too long for AF_UNIX (#6465) -- thanks @mxschmitt!
Fix remote-tmux mirror buffer truncation on a cross-DPI display move, and restore the bonsplit pointer so ssh-tmux tab reorders sync to tmux (#6393, #6438) -- thanks @robertnisipeanu!
Merge user --settings into injected hook settings in the claude wrapper (#5388) -- thanks @choi88andys!
Bound iOS pairing attempts and fix the Pair iPhone window (Cmd+W, sizing, layout, QR padding, failure copy) (#6495, #6038)
iOS (beta): fix native pairing sign-in failures (#6457) -- thanks @azooz2003-bit!
iOS (beta): fix the unread count badge contrast, stop pausing background music on text submit, and sustain hold-to-repeat Backspace (#6524, #6290, #6299)
Fix the changelog title clipping (#6425)