feat: sync course discovery filters with URL for shareable/bookmarkable search

Read facet filters (language, org, topic, etc.) from URL query params
and update the browser address bar after each search or filter change
so the URL always reflects the current filters.

This allows searches to be shared or bookmarked
via URLs like /courses?search_query=foo&language=pt

Co-authored-by: Claude Opus 4.6, through GitHub Copilot <223556219+Copilot@users.noreply.github.com>

Author: waldyrious

lms/static/js/discovery/discovery_factory.js

@@ -21,7 +21,23 @@
                 userLanguage: userLanguage,
                 userTimezone: userTimezone
             };
-            if (setDefaultFilter && userLanguage) {
+            // Read facet filters from URL query parameters and apply them.
+            var urlParams = new URLSearchParams(window.location.search);
+            urlParams.forEach(function(value, key) {
+                if (key === 'search_query') {
+                    return; // handled separately via the searchQuery argument
+                }
+                if (key in meanings) {
+                    filters.add({
+                        type: key,
+                        query: value,
+                        name: refineSidebar.termName(key, value)
+                    });
+                }
+            });
+
+            // Apply the default language filter, except when provided via URL parameters.
+            if (setDefaultFilter && userLanguage && !filters.get('language')) {
                 filters.add({
                     type: 'language',
                     query: userLanguage,
@@ -30,6 +46,20 @@
             }
             listing = new CoursesListing({model: courseListingModel});
 
+            function updateUrl() {
+                var params = new URLSearchParams();
+                filters.each(function(filter) {
+                    if (filter.id === 'search_query') {
+                        params.set('search_query', filter.get('query'));
+                    } else {
+                        params.set(filter.id, filter.get('query'));
+                    }
+                });
+                var qs = params.toString();
+                var newUrl = window.location.pathname + (qs ? '?' + qs : '');
+                history.replaceState(null, '', newUrl);
+            }
+
             dispatcher.listenTo(form, "search", function (query) {
                 form.showLoadingIndicator();
                 if (!query || query.trim() === "") {
@@ -79,6 +109,7 @@
                 form.hideLoadingIndicator();
                 listing.render();
                 refineSidebar.render();
+                updateUrl();
             });
 
             dispatcher.listenTo(search, 'error', function() {

lms/static/js/spec/discovery/discovery_factory_spec.js

@@ -225,4 +225,100 @@ define([
             expect(request.requestBody).toMatch(/language=en/);
         });
     });
+
+    describe('discovery.DiscoveryFactory URL sync', function() {
+        var originalSearch;
+        var replaceStateSpy;
+
+        function setUrlSearch(search) {
+            // Override window.location.search for the factory to read
+            originalSearch = window.location.search;
+            // Use history.replaceState to set query parameters without navigation
+            history.replaceState(null, '', window.location.pathname + search);
+        }
+
+        beforeEach(function() {
+            originalSearch = window.location.search;
+            replaceStateSpy = spyOn(history, 'replaceState').and.callThrough();
+            loadFixtures('js/fixtures/discovery.html');
+            TemplateHelpers.installTemplates([
+                'templates/discovery/course_card',
+                'templates/discovery/facet',
+                'templates/discovery/facet_option',
+                'templates/discovery/filter',
+                'templates/discovery/filter_bar'
+            ]);
+            jasmine.clock().install();
+        });
+
+        afterEach(function() {
+            jasmine.clock().uninstall();
+            // Restore original URL
+            history.replaceState(null, '', window.location.pathname + originalSearch);
+        });
+
+        it('pre-populates filters from URL query params', function() {
+            setUrlSearch('?modes=honor');
+            DiscoveryFactory(MEANINGS);
+
+            var requests = AjaxHelpers.requests(this);
+            $('.discovery-submit').trigger('click');
+            var request = AjaxHelpers.currentRequest(requests);
+            expect(request.requestBody).toMatch(/modes=honor/);
+            expect($('.active-filter').length).toBe(1);
+        });
+
+        it('overrides default language filter with URL param', function() {
+            // Set URL with language filter different from the default
+            setUrlSearch('?language=hr');
+            // Call DiscoveryFactory with userLanguage='en' and setDefaultFilter=true
+            DiscoveryFactory(MEANINGS, '', 'en', 'Europe/Lisbon', true);
+
+            var requests = AjaxHelpers.requests(this);
+            $('.discovery-submit').trigger('click');
+            var request = AjaxHelpers.currentRequest(requests);
+            expect(request.requestBody).toMatch(/language=hr/);
+            expect(request.requestBody).not.toMatch(/language=en/);
+        });
+
+        it('ignores unrecognized URL params', function() {
+            setUrlSearch('?bogus=value');
+            DiscoveryFactory(MEANINGS);
+
+            var requests = AjaxHelpers.requests(this);
+            $('.discovery-submit').trigger('click');
+            var request = AjaxHelpers.currentRequest(requests);
+            expect(request.requestBody).not.toMatch(/bogus/);
+            expect($('.active-filter').length).toBe(0);
+        });
+
+        it('updates URL after search completes', function() {
+            setUrlSearch('');
+            DiscoveryFactory(MEANINGS);
+
+            var requests = AjaxHelpers.requests(this);
+            $('.discovery-input').val('test');
+            $('.discovery-submit').trigger('click');
+            AjaxHelpers.respondWithJson(requests, JSON_RESPONSE);
+            expect(replaceStateSpy).toHaveBeenCalled();
+            var lastCall = replaceStateSpy.calls.mostRecent();
+            expect(lastCall.args[2]).toMatch(/search_query=test/);
+        });
+
+        it('clears URL params when filters are reset', function() {
+            setUrlSearch('?language=en');
+            DiscoveryFactory(MEANINGS);
+
+            var requests = AjaxHelpers.requests(this);
+            // Trigger initial search to load results
+            $('.discovery-submit').trigger('click');
+            AjaxHelpers.respondWithJson(requests, JSON_RESPONSE);
+            // Clear all filters
+            $('#clear-all-filters').trigger('click');
+            // The clear triggers a new search with empty query
+            AjaxHelpers.respondWithJson(requests, JSON_RESPONSE);
+            var lastCall = replaceStateSpy.calls.mostRecent();
+            expect(lastCall.args[2]).toBe(window.location.pathname);
+        });
+    });
 });