My advice would be to only use HTMX for data state related operations. For something like an intelligent back button, unless it depends on resource state do not use the backend to calculate it.

The recommended htmx way would be to hook up an onclick button to inline js or if you dislike that, a function called goBackOrInbox. It can then be something like:

function goBackOrInbox() { if (document.referrer) { const path = new URL(document.referrer).pathname; if (path.startsWith('/inbox')) { history.back(); return; } } window.location.href = '/inbox'; }

And if you use that pattern a lot then you can parameterise the function with whatever the route should be.