Filtering by Tag with shadow page?

My client wants to filter and index her Projects by tag, but, the projects template would have an index of the available tags, clicking on a tag would then take you to an index Projects that have that tag, clicking on one of the projects take you to the individual project. At the same time she wants to keep a linear page structure so

projects/
      /project-a/
      /project-b/
      /project-c/

rather than logically would I would like to do

projects/
      /commercial-tag/
           /project-a/
           /project-c/
      /industrial-tag/
           /project-b/

How would I go about creating the page for an index of projects when a tag has been selected. I referred to this a shadow page in the title as I don’t know how best to describe it?

Check out the docs: https://getkirby.com/docs/cookbook/tags

You would add a tags field to each project that you can then filter by.

Thank you for replying, I think I understand how to do the filtering, my question is how to create the ‘shadow’ page with the linear file structure. The UX would be Index page of tags - > Index of projects of chosen tag -> Chosen project and I’m not sure how to create the “Index of projects of chosen tag” page, there would be no folder in the Content folder so I would not be able to use a template. Is there a solution to how I can achieve this?

The parent ptojects page would either show all projects or a filtered list similar to what is described in the docs i linked to. Or maybe i don’t understand what you mean with shadow page. Your tags would link to this parent

Thank you for taking the time to reply. What you suggested is ideal and is the most appropriate to implement, but my client is being very stubborn, she wants 3 pages. Firstly, an Index of the Tags, then once the user has clicked on a Tag; a index of the projects that have that tag, thirdly, once a specific project has been clicked from the previous page; a project page of the individual project. The second page I mentioned would be like a kind of ‘ghost’ page as no template would exist given the project structure is linear, it has to be linear as some projects would have multiple tags. Does that make sense?

Yes, but i still don‘t see the necessity of an extra page on top of the already existing projects page. Might make sense to point that out to the client, stubborn or not However, it can of course be achieved, either through an sdditional real page in the file system or through a route.