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How to Disable the Blue Siri Button When Selecting Text in macOS 27

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After upgrading to macOS 27 Golden Gate, you may notice a small blue Siri icon appearing beside selected text. It can show up in Apple apps, websites, and some third-party apps, sometimes only after certain text is selected.

The icon is part of the new Siri AI interface in macOS 27. Apple refers to it as the “Siri AI icon” in its Mac User Guide. Under the hood, the floating interface is tied to a private macOS feature flag called LightweightUI_macOS.

Apple does not currently provide a dedicated switch in System Settings for hiding only this floating button. There is, however, a targeted Terminal workaround that disables the interface while leaving Siri AI and other Apple Intelligence features available.

This guide covers the known behavior, the safest way to remove the button, how to restore it later, and which Apple-supported alternatives are available.

What is the blue Siri icon?

The blue icon is an entry point to Siri AI’s text-related actions.

Apple’s macOS 27 documentation says that when Siri AI is enabled, you can select text and move the pointer over the Siri AI icon “when it appears.” Siri can then work with that text.

Depending on the selection and app, Siri may offer actions such as:

  • Rewrite
  • Proofread
  • Summarize
  • Compose text
  • Provide feedback
  • Apply a custom edit request

These functions overlap with Apple’s Writing Tools, although the floating Siri interface is not limited to Writing Tools.

During the macOS 27 beta cycle, testers also saw contextual actions for things such as addresses, dates, contact information, flights, and package tracking. Apple has not published a complete list of every action supported by the final macOS 27 release, so those actions should be treated as context-dependent rather than guaranteed.

Why did it suddenly appear after updating?

The floating Siri interface was already present in early macOS 27 betas, but it was initially hidden behind a feature flag.

That flag is called:

LightweightUI_macOS

Beta users discovered that the interface could be manually enabled by changing Apple’s FeatureFlags preferences.

Later in the macOS 27 development cycle, Apple enabled the interface more broadly. By the public release, Apple had added instructions for using the Siri AI icon to the Mac User Guide.

That history explains why the button may feel unfamiliar even to people who regularly used Siri or Writing Tools on macOS 26. It is a new part of the macOS 27 Siri AI experience.

Why doesn’t the Siri button appear every time?

Apple has not published the exact rules macOS uses to decide when the floating icon should appear.

The wording in Apple’s own documentation gives us one useful clue. Apple says to interact with the Siri AI icon “when it appears.” That suggests the interface is intentionally conditional.

A few factors can affect it.

The app needs to expose usable text

Apple says Writing Tools work in most places where you write, including many third-party apps and websites.

Apps do not all handle text the same way. Some use standard macOS text fields. Others use custom editors or rendering systems. That can affect whether Siri recognizes a text selection and whether the floating interface appears.

This is why the button can work normally in one app and rarely appear in another.

The selected text can change the available actions

A full sentence or paragraph gives Siri more text to work with than a single character or short fragment.

Beta testing also showed that the type of selected content can affect the menu. An address, date, paragraph, or tracking number can lead to different actions.

Apple has not documented a minimum number of words or characters. Claims that the button requires an exact selection length are not supported by Apple’s documentation.

There can be a delay

Some macOS 27 users report that the button appears shortly after selecting text rather than immediately.

Apple does not document an exact delay, so there is no reliable timing rule.

Apple’s macOS 27 release notes include a known issue where “Ask Siri” can remain in context menus even when Siri is disabled.

That issue is separate from the floating blue button, but it shows that Siri UI visibility still has some rough edges in the first macOS 27 release.

The best way to disable only the floating Siri button

If you want to keep Siri AI but remove the blue button beside selected text, the most targeted known method is to disable the private LightweightUI_macOS feature flag.

This method has been used since the macOS 27 beta cycle and has also been confirmed by users on the public macOS 27.0 release.

There is one catch: Apple does not expose this as a supported setting. The feature flag is private, so Apple can change or remove it in a future macOS update.

Step 1: Open Terminal

Open:

Applications > Utilities > Terminal

You can also press Command + Space, search for Terminal, and open it from Spotlight.

Step 2: Run the command

Paste the following command into Terminal:

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

Press Return.

macOS may ask for your administrator password.

Terminal does not show dots, asterisks, or other characters while you type the password. Enter it normally and press Return.

Step 3: Restart the Mac

Restart macOS after applying the setting.

After the restart, the floating Siri AI button should stop appearing beside selected text.

What the Terminal command changes

The command creates an override for this Apple feature flag:

WritingTools
└── LightweightUI_macOS
    └── Enabled = false

The change targets the floating Lightweight UI.

It does not uninstall Apple Intelligence, remove Siri, or delete Writing Tools from the Mac.

That is the main reason to use this method if the floating icon is your only problem.

Check whether a feature flag override already exists

People who installed macOS 27 beta builds may already have a manual override.

You can check with:

sudo defaults read /Library/Preferences/FeatureFlags/Domain/WritingTools LightweightUI_macOS

If the override exists, Terminal should return a value for the feature.

A disabled override may appear similar to:

{
    Enabled = 0;
}

An enabled override may show:

{
    Enabled = 1;
}

If Terminal says the key or domain does not exist, macOS is probably using Apple’s default setting.

This check is useful on Macs that previously ran Golden Gate beta builds because old overrides can affect how the final release behaves.

How to restore Apple’s default behavior

If you decide to bring the floating Siri button back, remove the override rather than permanently forcing the feature on.

Run:

sudo defaults delete /Library/Preferences/FeatureFlags/Domain/WritingTools LightweightUI_macOS

Restart the Mac afterward.

Deleting the custom value lets macOS return to Apple’s default behavior.

That is cleaner than manually writing:

Enabled = true

A future version of macOS may change the default, and removing the override allows Apple’s configuration to take effect.

Can you turn it off without using Terminal?

Apple does not currently provide a switch specifically for the floating Siri icon.

There are supported options if you are willing to disable more Siri functionality.

Switch to Siri Classic

macOS 27 includes controls for choosing which version of Siri is allowed.

The setting is available through:

System Settings > Screen Time > Content & Privacy Restrictions > Siri

Depending on the Mac and configuration, the available choices can include:

  • Siri AI (Beta)
  • Siri Classic
  • Don’t Allow Siri

Choosing Siri Classic removes the new Siri AI experience and keeps the older Siri system.

This is an Apple-supported setting, so it is the safer choice for people who do not use Siri AI anyway.

It affects more than the floating button, however. Siri AI features tied to the newer system will also become unavailable.

Disable Siri completely

If you do not use Siri, you can disable it through macOS settings.

This is the broadest solution. It is unnecessary if your only complaint is the text-selection button.

There is also a known macOS 27 issue where some “Ask Siri” context-menu entries may continue to appear even after Siri has been disabled.

What about disabling Writing Tools?

macOS also lets you restrict Writing Tools through Screen Time and the Intelligence & Siri controls.

That may make sense if you do not use AI writing features anywhere on the Mac.

I would not use it as the first fix for the floating button.

The LightweightUI_macOS interface has been used for more than rewriting and proofreading. During macOS 27 development, it also surfaced contextual Siri actions.

Disabling Writing Tools and disabling the floating Siri UI are therefore different changes.

If you still want Writing Tools, use the LightweightUI_macOS override instead.

Can you disable the Siri button for one app?

There is no verified per-app switch for the floating Siri AI interface in macOS 27.

macOS has per-app Siri Suggestions and Privacy controls, including settings related to learning from an application and showing Siri suggestions.

Apple does not document those settings as controls for the floating Siri button.

The LightweightUI_macOS flag is also system-wide.

If the icon causes problems only in one application, there is currently no confirmed Apple setting that disables it only for that app.

“Ask Siri” in the right-click menu is a different feature

macOS 27 can also add an “Ask Siri” entry to context menus.

That menu item and the floating blue Siri icon are separate interfaces.

The Terminal command in this guide targets the Lightweight UI that appears around selected text.

It may not remove “Ask Siri” from right-click menus.

This distinction is useful when checking whether the workaround worked. If the floating button disappears but “Ask Siri” remains in a context menu, the feature flag has not necessarily failed.

Apple also lists a known macOS 27 bug where “Ask Siri” can remain in context menus even when Siri is turned off.

You can still use Writing Tools after hiding the button

Removing the floating button does not necessarily remove the normal Writing Tools interface.

You can usually select text and open Writing Tools through the standard macOS context menu.

Depending on the app and your Apple Intelligence settings, available actions can include:

  • Rewrite
  • Proofread
  • Summarize
  • Change tone
  • Create key points
  • Convert text into a list or table
  • Apply a custom requested change

This makes the feature-flag method useful for people who want Writing Tools but dislike the floating pop-up.

If the command does not work

Start with a full restart. Changes to FeatureFlags preferences may not take effect immediately.

Then check the stored value:

sudo defaults read /Library/Preferences/FeatureFlags/Domain/WritingTools LightweightUI_macOS

Make sure it reports the feature as disabled.

Also confirm that the remaining interface is actually the floating blue Siri button. An “Ask Siri” item in a right-click menu is controlled separately.

If the setting stops working after a future macOS update, remove the override:

sudo defaults delete /Library/Preferences/FeatureFlags/Domain/WritingTools LightweightUI_macOS

Restart the Mac and check whether Apple has added a supported setting or changed the feature.

Private FeatureFlags values are not guaranteed to remain stable between macOS releases.

Is the blue Siri button a macOS bug?

The button itself is an intentional macOS 27 feature.

Apple’s documentation tells users to select text and interact with the Siri AI icon when it appears.

The inconsistent placement, unexpected appearances, or behavior inside certain apps may involve bugs or app compatibility issues. Apple has not published a complete list of known problems specific to the Lightweight UI.

Treat the existence of the button and problems with its behavior as two separate issues.

Which fix should you use?

Use the Terminal feature flag if you want to keep Siri AI and Writing Tools but remove the floating button:

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

Use Siri Classic if you do not need Siri AI and prefer an Apple-supported setting.

Disable Siri completely if you do not use Siri at all.

Disable Writing Tools if you specifically want to remove AI writing functions rather than only the floating interface.

For most people who only dislike the blue selection button, the LightweightUI_macOS override is the most precise option currently available. Keep the rollback command with it so you can return to Apple’s default after a future macOS update:

sudo defaults delete /Library/Preferences/FeatureFlags/Domain/WritingTools LightweightUI_macOS

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