Chrome per-origin notification gating versus OS Focus modes: coordinating delivery guarantees

Direct answers

1. Observable signals: Chrome-quiet → DevTools shows entry flagged quiet/suppressed with no banner, sound or badge; OS Focus/DND → DevTools shows normal delivery entry while the OS notification center displays a muted icon or no banner/sound/badge.
2. Chrome site-specific settings (sound, vibration, popup) cannot override OS Focus/Do Not Disturb; the OS layer acts after Chrome decides to show the notification, so Chrome’s settings are ignored when the OS suppresses it.
3. Chrome’s engagement metrics (recent clicks, dismissals, frequency) drive its quiet heuristic locally; OS notification history is not shared with Chrome, so each system makes an independent decision. A notification may be demoted by Chrome even if the OS would surface it, and vice‑versa.

Confirmed facts

• Chrome’s quiet-notification heuristic suppresses presentation (no banner, sound, badge) while still counting the notification as delivered; DevTools > Application > Notifications lists the entry as quiet or suppressed.
• When OS Focus/Do Not Disturb blocks a notification, Chrome still receives the push and shows it in its notification center (if the site has permission), but the OS does not surface a banner, sound or badge; DevTools shows a normal delivery entry and the OS center indicates the mute (e.g., macOS Notification Center shows a muted icon).
• Chrome site-specific settings for sound, vibration or popup behavior cannot override OS Focus/DND grouping or timing; the OS suppression occurs after Chrome’s decision, so Chrome’s settings are ignored.
• Chrome’s engagement metrics (recent clicks, dismissals, frequency) are used locally to decide whether to apply quiet heuristics; OS notification history (e.g., recent dismissals via Action Center) is not shared with Chrome, so the two systems make independent decisions.

Likely explanation / reasoning

The quiet heuristic is an internal Chrome ranking that lowers prominence based on recent user interaction with the origin; it does not communicate with the OS, so the OS sees a normal notification request and may still block it via Focus/DND. Conversely, the OS can block a notification that Chrome would have presented prominently because the OS has no knowledge of Chrome’s engagement score. This independence explains why the observable signals differ: Chrome-quiet shows a suppression flag in DevTools but the OS center receives nothing; OS-block shows a normal DevTools entry while the OS center shows a muted or absent notification.

Verification steps

1. Open Chrome DevTools → Application → Notifications.
2. Trigger a notification from a site that has permission.
3. If the entry shows a quiet/suppressed flag and no OS banner/sound/badge appears, the suppression originated from Chrome’s quiet heuristic.
4. Enable OS Focus/Do Not Disturb (Windows Focus Assist, macOS DND/Focus, Linux DND) and repeat the trigger.
5. If DevTools shows a normal delivery entry (no quiet flag) while the OS notification center displays no banner/sound/badge or a muted icon, the suppression is due to the OS mode.
6. Toggle Chrome site-specific settings (Site Settings → Notifications → Sound/Vibration) and repeat; observe that OS suppression persists, confirming Chrome cannot override OS Focus/DND.