Apple is testing a significant redesign of Mail’s compose window in macOS 27 Golden Gate that pushes “Write with Siri” into the most prominent position in the formatting bar, with classic text controls shunted to the far right and hidden entirely once you start a Siri-assisted draft. This was reported on the macOSBeta Subreddit, who enabled it through an internal feature flag in Beta 4.
What the Redesigned Bar Actually Does
The reworked formatting bar is a meaningful departure from how Mail has always presented composition tools. Instead of leading with bold, italic, font size, and attachment buttons, the new bar leads with Siri. The redesign adds and changes these elements:
- Write with Siri occupies the most prominent position in the composer bar
- Traditional formatting controls are collapsed to the right edge by default
- Once you select Write with Siri and start typing a prompt, the formatting controls disappear entirely
- Contextual Smart Reply suggestions from Siri appear in the bar without requiring you to use them in your draft
- After selecting a Siri-generated composition, the bar shows “Edit with Siri,” “Proofread,” “Rewrite,” and “How does this sound?” options
That last set of options is the more interesting part. Getting a full draft from Siri and then being able to immediately probe its tone or request a rewrite from within the same compose window is a tighter workflow than what Apple Intelligence offered in earlier iterations, where you had to hunt for those tools.
Still Buggy, Still Hidden
The redesign is locked behind a feature flag, meaning it is off by default and requires deliberately enabling it to see it. In Beta 4, the new bar only appears when you are replying to an existing message. Composing a fresh email still pulls up the old formatting bar. That is a fairly significant gap for a feature that is supposedly central to the new Mail experience.
You can enable it by entering the below command in Terminal, and restarting your Mac:
sudo mkdir -p /Library/Preferences/FeatureFlags/Domain && \
sudo defaults write /Library/Preferences/FeatureFlags/Domain/WritingTools FormattingBar_macOS -dict Enabled -bool true
You can disable it by entering the below command in Terminal and restarting it again:
sudo defaults delete /Library/Preferences/FeatureFlags/Domain/WritingTools FormattingBar_macOS
Whether it makes the final cut for the September release is genuinely unclear. Apple regularly tests features behind flags that never ship, and the current state suggests this one still has meaningful work left. The September timeline is tight given that macOS 27 Golden Gate ships alongside the iPhone 18 Pro and Apple’s first foldable iPhone.
The Mail compose redesign is not an isolated experiment. Beta 4 also contains a hidden popover interface for Siri AI that surfaces Writing Tools and contextual actions whenever you select text anywhere in the system, appearing near the selected text and expanding on hover into a compact panel of tools. Apple is clearly threading Siri AI into the OS at a very granular level rather than keeping it confined to a dedicated Siri panel.
Siri AI in macOS 27 Golden Gate is a different product from the Siri that shipped with prior versions of macOS. It uses generative AI models, can hold back-and-forth conversations, and has access to your personal data across Mail, Messages, Notes, Reminders, and Calendar. Write with Siri specifically can generate text from scratch, fix grammar, or give feedback on your writing. Putting it at the top of the Mail compose window is less about convenience and more about making it impossible to ignore.
