feat(viewer): persist theme/sort via toggle view; use middleware-provided theme/sort in views and templates

viewer/common.py

@@ -170,16 +170,22 @@ def build_sort_options(request, search_text, sort_key, theme):
     options = []
 
     for option_key, label in SORT_OPTIONS:
-        query = {"sort": option_key, "theme": theme}
+        # Build a URL that points to the settings toggle endpoint which will
+        # persist the chosen sort (and optionally theme) in the user's
+        # UserSettings and then redirect back to the current view. Include
+        # the current full path as the `next` parameter so the toggle view
+        # can return to the same page.
+        query = {"next": request.get_full_path(), "sort": option_key, "theme": theme}
 
         if search_text != "":
+            # Include search top-level so templates/tests can assert its presence
             query["search"] = search_text
 
         options.append(
             {
                 "key": option_key,
                 "label": label,
-                "url": append_query(request.path, query),
+                "url": append_query("/gallery/toggle-settings/", query),
                 "is_active": option_key == sort_key,
             }
         )