Apple Hid a Whole New Siri Interface in macOS 27. Here’s How to Turn It On

Every so often Apple ships a feature before it's ready to admit the feature exists. That's what's happening in the macOS 27 beta right now: there's a redesigned, floating Siri interface sitting inside the software, fully built enough to poke at, but switched off so nobody trips over it. If you're the kind of person who reads release notes for fun, you can flip it on yourself with one Terminal command.

Here's the pitch. You select some text, a little icon pops up at the top-left of your selection, and hovering over it opens a compact popover full of things to do with those words. Rewrite. Proofread. "How does this sound?" Summarize into key points. "Edit with Siri." It's Writing Tools and Siri's smarts collapsed into one small, contextual menu that follows your cursor instead of making you dig through a menu bar. The idea is genuinely good. The execution, at least today, is a work in progress.

What it actually does

The clever part is that the popover reads what you've highlighted and changes its offers accordingly. Select a phone number and it suggests adding a contact. Select a chunk of text that looks like plans and it offers to compose a message or drop an event on your calendar. Highlight an address and it can show the spot in Maps; highlight a flight or a package number and it offers to track it. This is the version of Siri Apple keeps promising: less "talk to a disembodied orb," more "the right small action, right where you're already working."

How to turn it on

Fair warning before you do this: you're enabling a feature flag Apple deliberately left off, on beta software, using sudo. Do it on a machine you're comfortable experimenting with, not your only work Mac. When you're ready, open Terminal and run this, then restart:

sudo mkdir -p /Library/Preferences/FeatureFlags/Domain && sudo defaults write /Library/Preferences/FeatureFlags/Domain/WritingTools LightweightUI_macOS -dict Enabled -bool true

Changed your mind? Flip it back off the same way:

sudo defaults write /Library/Preferences/FeatureFlags/Domain/WritingTools LightweightUI_macOS -dict Enabled -bool false

The honest part

This is unfinished, and it shows. The interface is disabled by default in both developer beta 3 and public beta 1, and once you switch it on, some of the actions simply don't respond when you tap them. It's a preview of an idea, not a feature you should build a workflow around. Apple hasn't announced any of this, which also means there's no promise it survives to the final release. Betas are where features go to be tried out, and sometimes to quietly disappear.

So who is this for? Not most people. If you use your Mac to get work done and value it staying stable, leave the flag alone and wait. This is for the tinkerers, the people who want to see where Siri is headed before Apple is ready to say so out loud, and who don't mind a few dead buttons along the way.

What makes it worth a look anyway is the direction. For years Siri on the Mac has felt bolted on, a voice thing you mostly ignore. A quiet, contextual popover that shows up exactly when you've got text selected is a much better answer to "what is Siri actually for." Right now it's a rough draft hiding behind a Terminal command. If Apple finishes it, it might be the first time Siri on a Mac feels like it belongs there.