Desktop app

The mxr desktop app is a window around the local web app. It opens your mail in its own window, a system-wide shortcut starts a new message, and when mxr isn’t running it says so instead of showing a broken page.

It is the same app mxr web opens in a browser. The daemon is still the system: SQLite, search, provider sync, credentials and background work all stay in mxr. The desktop app bundles none of that.

What you need

• macOS on Apple silicon. Linux and Windows aren’t built yet.
• mxr installed (brew install planetaryescape/mxr/mxr). The app looks for it on your PATH, then in /opt/homebrew/bin, /usr/local/bin, ~/.cargo/bin and ~/.local/bin, because apps opened from Finder don’t get your shell’s PATH.

Install the app with Homebrew:

brew install --cask planetaryescape/mxr/mxr-desktop

The cask installs mxr too if you don’t have it. Each release also attaches mxr-desktop-<version>-aarch64.dmg to its GitHub release. To build it yourself, run cd apps/desktop && npm ci --ignore-scripts && npx tauri build --bundles app; the bundle lands in apps/desktop/src-tauri/target/release/bundle/macos/mxr.app, unsigned.

The release build is signed with a Developer ID certificate. Notarisation runs when the release has App Store Connect API credentials. A build without them is signed but not notarised, and macOS then asks you to confirm the first launch. The release’s job summary says which of the two happened.

What it does

On launch the app runs mxr web --print-url --no-open, which starts or reuses the local web bridge, and loads the address it prints. Closing the window hides it; the Dock icon or the shortcut brings it back, and Command+Q quits.

Only one copy runs. Opening a second one focuses the first.

The window remembers its size and position. It has the standard macOS menu, so copy, paste and the other text shortcuts work.

New message from anywhere

Press Control+Option+Command+M in any app. mxr comes forward and opens a new message over whatever you were looking at, so closing it with Esc puts you back where you were. The shortcut is deliberately not Command+Shift+M, which Mail and Chrome already use.

To pick another key, set MXR_DESKTOP_SHORTCUT before launching, for example MXR_DESKTOP_SHORTCUT=super+shift+m. If the combination is taken by another app, the window still works without it.

When mxr isn’t running

If mxr can’t be found, or mxr web fails or doesn’t answer within 15 seconds, the window shows “mxr isn’t running” with the command to start the daemon:

mxr daemon

Run it in a terminal and press Try again. Once the web app is open, its own offline banner covers a daemon that goes away later.

Links, attachments and safety

The window only shows the web app it got from mxr web and its own down page. Links to other sites open in your default browser. Attachments you download save to your Downloads folder, and an existing file is never overwritten. The app grants no Tauri commands to any page, so the web app and the mail it renders can’t call into the shell.

Still works in a browser

mxr web keeps working. It opens the same app at http://mxr.localhost:42829, installable as a PWA if you prefer that to the desktop app.

What it isn’t

There is no menu-bar item, no notifications and no built-in updater. The web app inside the window comes from the mxr you have installed, so brew upgrade mxr updates it. brew upgrade --cask mxr-desktop updates the window around it.