fix(workingset): reposition selection marker when working set becomes visible

The working set selection highlight is an absolutely positioned marker div
that only moves when a selectionChanged event fires. On startup the
working set container gets the working-set-hidden class (the showWorkingSet
pref is read before it is defined), so the session-restore file open
positions the marker while the container is display:none - every offset
computes to 0 and the marker parks on the first row. The same stale marker
happens when the current file changes while the working set is hidden via
the showWorkingSet pref or while another sidebar tab (e.g. AI) is active.

Add WorkingSetView.refreshSelection() which recomputes the selection
marker and scrolls the selected item into view, and call it when the
showWorkingSet pref un-hides the container and when switching back to the
files sidebar tab. Note refresh() cannot be used for this as it restores
the pre-redraw scrollTop, which reads 0 on hidden elements and would undo
the scroll-into-view.

Adds integration tests for both paths in mainview:WorkingSetView.

Claude-Session: https://claude.ai/code/session_018BpQ3Z7w4H2U5qrPGWYRWB

Author: abose

src/project/SidebarView.js

@@ -301,6 +301,9 @@ define(function (require, exports, module) {
                 if(getPref) {
                     // refer to brackets.less file for styles
                     $workingSet.removeClass("working-set-hidden");
+                    // marker positions computed while the container was display:none are
+                    // all 0, so recompute the selection now that it is visible again
+                    WorkingSetView.refreshSelection();
                 } else {
                     $workingSet.addClass("working-set-hidden");
                 }

src/project/WorkingSetView.js

@@ -121,6 +121,17 @@ define(function (require, exports, module) {
      */
     var _DRAG_MOVE_DETECTION_START = 3;
 
+    /**
+     * Recomputes the selection marker of all Pane View List Views and scrolls
+     * the selected item into view. Needed after the working set becomes visible
+     * again, as marker positions computed while it was display:none are all 0.
+     */
+    function refreshSelection() {
+        _.forEach(_views, function (view) {
+            view._updateListSelection();
+        });
+    }
+
     /**
      * Refreshes all Pane View List Views
      */
@@ -1628,6 +1639,7 @@ define(function (require, exports, module) {
     // Public API
     exports.createWorkingSetViewForPane   = createWorkingSetViewForPane;
     exports.refresh                       = refresh;
+    exports.refreshSelection              = refreshSelection;
     exports.addIconProvider               = addIconProvider;
     exports.addClassProvider              = addClassProvider;
     exports.syncSelectionIndicator        = syncSelectionIndicator;

src/view/SidebarTabs.js

@@ -40,7 +40,8 @@ define(function (require, exports, module) {
     const AppInit              = require("utils/AppInit"),
         EventDispatcher      = require("utils/EventDispatcher"),
         Metrics              = require("utils/Metrics"),
-        PreferencesManager   = require("preferences/PreferencesManager");
+        PreferencesManager   = require("preferences/PreferencesManager"),
+        WorkingSetView       = require("project/WorkingSetView");
 
     // --- Constants -----------------------------------------------------------
 
@@ -447,6 +448,11 @@ define(function (require, exports, module) {
         }
 
         if (previousTabId !== id) {
+            if (id === SIDEBAR_TAB_FILES) {
+                // working set marker positions computed while the files tab content was
+                // display:none are all 0, so recompute the selection now that it is visible
+                WorkingSetView.refreshSelection();
+            }
             exports.trigger(EVENT_TAB_CHANGED, id, previousTabId);
         }
     }

test/spec/WorkingSetView-integ-test.js

@@ -107,6 +107,11 @@ define(function (require, exports, module) {
         });
 
         afterEach(async function () {
+            // restore state in case a selection marker test failed midway
+            testWindow.brackets.test.PreferencesManager.set("showWorkingSet", true);
+            const SidebarTabs = testWindow.brackets.test.SidebarTabs;
+            SidebarTabs.setActiveTab(SidebarTabs.SIDEBAR_TAB_FILES);
+            testWindow.$(".open-files-container").css("height", "");
             await testWindow.closeAllFiles();
         });
 
@@ -341,6 +346,89 @@ define(function (require, exports, module) {
             });
         });
 
+        function _isMarkerAlignedWithSelection() {
+            const $ = testWindow.$;
+            const $selected = $(".open-files-container li.selected");
+            const $marker = $(".open-files-container .sidebar-selection");
+            return $selected.length === 1 && $marker.length === 1 &&
+                Math.abs($marker.offset().top - $selected.offset().top) < 2;
+        }
+
+        it("should reposition selection marker and reveal selection when working set is shown again", async function () {
+            const $ = testWindow.$;
+            const PreferencesManager = testWindow.brackets.test.PreferencesManager;
+            const fileList = MainViewManager.getWorkingSet(MainViewManager.ACTIVE_PANE);
+            const $container = $(".open-files-container");
+
+            // view the first file
+            await awaitsForDone(CommandManager.execute(Commands.FILE_OPEN, { fullPath: fileList[0].fullPath }),
+                "FILE_OPEN first file");
+
+            // shrink the list so the second item overflows and must be scrolled to
+            $container.css("height", "30px");
+            $container.scrollTop(0);
+
+            // hide the working set
+            PreferencesManager.set("showWorkingSet", false);
+            await awaitsFor(function () {
+                return $("#working-set-list-container").hasClass("working-set-hidden");
+            }, "working set to hide");
+
+            // switch to the second file while hidden - marker offsets all compute
+            // to 0 on display:none elements, so it cannot be positioned now
+            await awaitsForDone(CommandManager.execute(Commands.FILE_OPEN, { fullPath: fileList[1].fullPath }),
+                "FILE_OPEN second file");
+
+            // show the working set again
+            PreferencesManager.set("showWorkingSet", true);
+            await awaitsFor(function () {
+                return !$("#working-set-list-container").hasClass("working-set-hidden");
+            }, "working set to show");
+
+            // the marker must align with the newly selected item and the item
+            // must be scrolled into view
+            await awaitsFor(_isMarkerAlignedWithSelection, "selection marker to align with selected item");
+            await awaitsFor(function () {
+                const $selected = $(".open-files-container li.selected");
+                const containerTop = $container.offset().top;
+                const containerBottom = containerTop + $container.height();
+                return $selected.offset().top >= containerTop &&
+                    ($selected.offset().top + $selected.height()) <= containerBottom;
+            }, "selected item to be scrolled into view");
+        });
+
+        it("should reposition selection marker when switching back to the files sidebar tab", async function () {
+            const $ = testWindow.$;
+            const SidebarTabs = testWindow.brackets.test.SidebarTabs;
+            const fileList = MainViewManager.getWorkingSet(MainViewManager.ACTIVE_PANE);
+            const TEST_TAB = "sidebar-tab-wsv-selection-test";
+
+            // view the first file
+            await awaitsForDone(CommandManager.execute(Commands.FILE_OPEN, { fullPath: fileList[0].fullPath }),
+                "FILE_OPEN first file");
+
+            // switch to another sidebar tab, which hides the files tab content
+            SidebarTabs.addTab(TEST_TAB, "wsv test", "fa-solid fa-flask");
+            SidebarTabs.setActiveTab(TEST_TAB);
+            await awaitsFor(function () {
+                return !$("#working-set-list-container").is(":visible");
+            }, "working set to be hidden by tab switch");
+
+            // switch to the second file while the files tab content is hidden
+            await awaitsForDone(CommandManager.execute(Commands.FILE_OPEN, { fullPath: fileList[1].fullPath }),
+                "FILE_OPEN second file");
+
+            // switch back to the files tab
+            SidebarTabs.setActiveTab(SidebarTabs.SIDEBAR_TAB_FILES);
+            await awaitsFor(function () {
+                return $("#working-set-list-container").is(":visible");
+            }, "working set to be visible again");
+
+            await awaitsFor(_isMarkerAlignedWithSelection, "selection marker to align with selected item");
+
+            SidebarTabs.removeTab(TEST_TAB);
+        });
+
         it("should allow refresh to be used to update the class list", async function () {
             function classProvider(file) {
                 return "one";