# cmux 0.64.13: Browser Focus Mode, SSH Agent Forwarding, Custom Sidebars (Beta), Major Stability Fixes

[ Changelog](https://cmux.com/docs/changelog)


June 4, 2026

### Browser Focus Mode

Browser panes get a focus mode that strips away the surrounding chrome so a single page can take over the pane while you read or work in it.

### SSH Agent Forwarding

\`cmux ssh\` now forwards your local SSH agent, so remote sessions can use your local keys for git pushes and further hops without copying private keys onto the remote.

### Vibe-Codable Custom Sidebars (Beta)

Build your own sidebar with a runtime Swift interpreter, behind the Beta Features flag. Edit the sidebar source, validate it from the CLI, and reload it live without rebuilding the app.

### Browser Mouse Back & Forward

The browser now responds to the dedicated back and forward buttons on a mouse, so side-button navigation works the way it does in a normal browser.

### Major Stability & Performance Fixes

Fixed a settings-observation leak that grew the app to 4.4 GB over a day, a browser render loop burning ~39% of the main thread on every CoreAnimation commit, a WebKit crash after sleep/wake, a 100% CPU hang in the Markdown and file-preview editor, and child processes launching under Rosetta on Apple Silicon.

Added

-   Browser focus mode ([#4573](https://github.com/manaflow-ai/cmux/pull/4573))
-   SSH agent forwarding for `cmux ssh`, so remote sessions can use your local SSH keys ([#5301](https://github.com/manaflow-ai/cmux/pull/5301))
-   Vibe-codable custom sidebars: a runtime Swift interpreter for building your own sidebar, behind a Beta Features flag, with CLI validation and live reload ([#5254](https://github.com/manaflow-ai/cmux/pull/5254), [#5327](https://github.com/manaflow-ai/cmux/pull/5327)) -- thanks @azooz2003-bit!
-   Browser mouse back and forward button support ([#5197](https://github.com/manaflow-ai/cmux/pull/5197))
-   Persisted word-wrap setting for the file editor ([#5247](https://github.com/manaflow-ai/cmux/pull/5247))
-   "Open Current Directory in Devin" command ([#5288](https://github.com/manaflow-ai/cmux/pull/5288)) -- thanks @MaxiAschenbrenner!
-   Live status reporting in the Amp Neo session plugin, driving the cmux tab status bar ([#5235](https://github.com/manaflow-ai/cmux/pull/5235)) -- thanks @HamptonMakes!

Changed

-   Anchor the textbox autocomplete to the cursor ([#5021](https://github.com/manaflow-ai/cmux/pull/5021))
-   Add a font-size popover to the Markdown viewer controls ([#5168](https://github.com/manaflow-ai/cmux/pull/5168))
-   Open group config files in your configured editor ([#5250](https://github.com/manaflow-ai/cmux/pull/5250))
-   Isolate browser WebKit process pools so one browser pane crashing no longer takes down the others ([#4987](https://github.com/manaflow-ai/cmux/pull/4987))
-   Move large scrollback read-text work off the main actor to reduce UI hangs ([#5243](https://github.com/manaflow-ai/cmux/pull/5243)) -- thanks @azooz2003-bit!

Fixed

-   Fix a settings-observation task leak that grew the app process to 4.4 GB over ~23h ([#5310](https://github.com/manaflow-ai/cmux/pull/5310))
-   Fix a browser pane render loop that re-navigated the WebView on every CoreAnimation commit (~39% main-thread CPU) ([#5311](https://github.com/manaflow-ai/cmux/pull/5311))
-   Fix a WebKit post-wake crash with sleep/wake-aware hidden-webview discard scheduling ([#5315](https://github.com/manaflow-ai/cmux/pull/5315)) -- thanks @azooz2003-bit!
-   Fix the Markdown and file-preview text editor hanging at 100% CPU on click or drag-select by forcing a TextKit 1 stack ([#5257](https://github.com/manaflow-ai/cmux/pull/5257))
-   Stop cmux from launching child processes under Rosetta on Apple Silicon ([#5306](https://github.com/manaflow-ai/cmux/pull/5306)) -- thanks @CharlesWiltgen for the report!
-   Recover terminal focus when the first responder is stranded in another window ([#5296](https://github.com/manaflow-ai/cmux/pull/5296))
-   Fix the browser address bar so a single click places a caret instead of selecting the whole URL ([#5270](https://github.com/manaflow-ai/cmux/pull/5270))
-   Fix copy-mode vim keys (j/k/h/l) swallowed under non-ASCII input sources (Korean, Japanese Kana, Zhuyin) ([#5292](https://github.com/manaflow-ai/cmux/pull/5292)) -- thanks @pstanton237!
-   Fix terminal copy-mode cursor navigation ([#5328](https://github.com/manaflow-ai/cmux/pull/5328))
-   Fix terminal selection on mouse-up while the find overlay is open ([#5335](https://github.com/manaflow-ai/cmux/pull/5335))
-   Fix TextBox IME and input-source handling ([#5340](https://github.com/manaflow-ai/cmux/pull/5340))
-   Fix the macOS "wants to access data from other apps" prompt on agent session start and quit by moving the control socket out of Application Support ([#5176](https://github.com/manaflow-ai/cmux/pull/5176))
-   Fix Codex auto-resume emitting an invalid `-s disabled` sandbox flag ([#5276](https://github.com/manaflow-ai/cmux/pull/5276)) -- thanks @taonetm7 for the report!
-   Fix agent session resume cd-ing into the wrong directory after a cwd drift, plus post-kill cwd handling ([#5300](https://github.com/manaflow-ai/cmux/pull/5300), [#5312](https://github.com/manaflow-ai/cmux/pull/5312))
-   Fix restored cwd bindings after a reboot ([#5307](https://github.com/manaflow-ai/cmux/pull/5307))
-   Fix a stale sidebar git branch after cd-ing out of a repo into a non-git directory ([#5279](https://github.com/manaflow-ai/cmux/pull/5279))
-   Fix a TextBox teardown crash when toggling the sidebar background ([#5317](https://github.com/manaflow-ai/cmux/pull/5317))
-   Fix a workspace-close teardown hang ([#5316](https://github.com/manaflow-ai/cmux/pull/5316)) -- thanks @azooz2003-bit!
-   Fix the workspace-group "Delete Group" context-menu action being a no-op ([#5253](https://github.com/manaflow-ai/cmux/pull/5253))
-   Fix the diff viewer showing a raw CLI error and beeping when there is no diff ([#5252](https://github.com/manaflow-ai/cmux/pull/5252))
-   Fix sidebar drag-and-drop frame collection with the lazy (virtualized) sidebar ([#5325](https://github.com/manaflow-ai/cmux/pull/5325))
-   Lazy-load file explorer roots to speed up opening the file tree ([#5342](https://github.com/manaflow-ai/cmux/pull/5342))
-   Fix Claude workflow resume transcript resolution ([#5242](https://github.com/manaflow-ai/cmux/pull/5242)) -- thanks @azooz2003-bit!
-   Fix opening the remote SSH file browser ([#5241](https://github.com/manaflow-ai/cmux/pull/5241)) -- thanks @azooz2003-bit!
-   Fix custom-sidebar extension discovery for tagged builds ([#5267](https://github.com/manaflow-ai/cmux/pull/5267)) -- thanks @azooz2003-bit!
-   Fix Sparkle update packaging and Claude hook transcript scaling ([#5202](https://github.com/manaflow-ai/cmux/pull/5202))

Contributors

[![austinywang](https://cmux.com/_next/image?url=https%3A%2F%2Fgithub.com%2Faustinywang.png%3Fsize%3D48&w=48&q=75)austinywang](https://github.com/austinywang) [![azooz2003-bit](https://cmux.com/_next/image?url=https%3A%2F%2Fgithub.com%2Fazooz2003-bit.png%3Fsize%3D48&w=48&q=75)azooz2003-bit](https://github.com/azooz2003-bit) [![CharlesWiltgen](https://cmux.com/_next/image?url=https%3A%2F%2Fgithub.com%2FCharlesWiltgen.png%3Fsize%3D48&w=48&q=75)CharlesWiltgen](https://github.com/CharlesWiltgen) [![HamptonMakes](https://cmux.com/_next/image?url=https%3A%2F%2Fgithub.com%2FHamptonMakes.png%3Fsize%3D48&w=48&q=75)HamptonMakes](https://github.com/HamptonMakes) [![lawrencecchen](https://cmux.com/_next/image?url=https%3A%2F%2Fgithub.com%2Flawrencecchen.png%3Fsize%3D48&w=48&q=75)lawrencecchen](https://github.com/lawrencecchen) [![MaxiAschenbrenner](https://cmux.com/_next/image?url=https%3A%2F%2Fgithub.com%2FMaxiAschenbrenner.png%3Fsize%3D48&w=48&q=75)MaxiAschenbrenner](https://github.com/MaxiAschenbrenner) [![pstanton237](https://cmux.com/_next/image?url=https%3A%2F%2Fgithub.com%2Fpstanton237.png%3Fsize%3D48&w=48&q=75)pstanton237](https://github.com/pstanton237) [![taonetm7](https://cmux.com/_next/image?url=https%3A%2F%2Fgithub.com%2Ftaonetm7.png%3Fsize%3D48&w=48&q=75)taonetm7](https://github.com/taonetm7)

[ cmux 0.64.12](https://cmux.com/docs/changelog/0.64.12) [cmux 0.64.14 ](https://cmux.com/docs/changelog/0.64.14)

Canonical: https://cmux.com/docs/changelog/0.64.13

Documentation index: https://cmux.com/llms.txt