Sorry for the long comment, but I took some time to read the whole discussion and I honestly do not understand the argument for keeping “external” tags visible.
If someone chooses to enable Focus on Tag, it is specifically because they do not want notes, tags, or private information from other areas to be exposed while they are working inside a specific context, like a work workspace. For that reason, I think the sidebar should only show the children of the focused tag.
The only exception I can imagine is inside individual notes. For example, if a note contains #work/invoices, #personal/taxes, and #finance/expenses, and I am currently focused on #work, then the other tags could maybe still be shown in a dimmed or visually different way. That would make it clear that the note is also connected to things outside the current workspace, without breaking the focused view in the sidebar. Clicking one of those links could prompt the user to deactivate focus mode, or to add a new tag to it (as mentioned below) ![]()
In general, since this would be a completely optional feature, I think people who are not interested in this behavior could simply leave it turned off. That is why I do not really see the issue with making the focused experience actually behave in a strict and coherent way.
As a possible middle ground, I mentioned in a previous post the idea of being able to focus on multiple tags at the same time. In that model, the sidebar would show only the branches related to the selected focus tags, and not every other unrelated tag in the system. To me, that feels much more consistent with the purpose of the feature.
Also, I am really happy that this possibility is being seriously considered. For me, it is probably the most important feature after note versioning.
[Edit] I think I do understand the concern from the other side. If you rely heavily on cross-referencing tags across different areas, hiding external tags might feel like losing visibility on those connections. Bear’s tagging system is powerful precisely because a single note can belong to multiple contexts at once, and a strict focus mode could make that less obvious. I get that. I just think that if someone is explicitly choosing to activate Focus on Tag, they are accepting that tradeoff, and the feature should respect that intent. The multi-tag focus idea could also help here, since you could always widen the scope if you need to see more connections.

