The precise logic is described in the PR description:
Anonymous Behavior:
On topic list:
- Regardless of focus, browser title shows the count of topics waiting to be loaded (matches the “See N new or updated topic” banner)
On topic:
- IF tab is in the background, then increment the counter for each new post that arrives
- When focus is restored, reset the counter
Logged in behavior
For logged in users:
- If tab is in the background, and a new notification arrives while the tab is in the background, display the total notification count in the title
- Hide the count when the tab is in the foreground
@ChrisBeach does this line up with what you’re seeing?