feat: add SidebarView resize API and auto-widen sidebar for AI tab

- Add SidebarView.resize(width) and SidebarView.getWidth() APIs for
  programmatic sidebar resizing with proper persistence and resync
- Auto-widen sidebar to 370px on first AI tab activation when narrower
  than the preferred width, using a one-time view state flag
- Switch to Files tab when Show in File Tree is triggered from another tab
- Expose SidebarView on brackets.test for integration tests
- Add integration tests for resize API, Show in File Tree tab switching,
  and sidebar width save/restore

Author: abose

src/brackets.js

@@ -294,6 +294,7 @@ define(function (require, exports, module) {
             SearchResultsView: require("search/SearchResultsView"),
             ScrollTrackMarkers: require("search/ScrollTrackMarkers"),
             SidebarTabs: require("view/SidebarTabs"),
+            SidebarView: require("project/SidebarView"),
             WorkingSetView: require("project/WorkingSetView"),
             doneLoading: false
         };

src/project/SidebarView.js

@@ -326,9 +326,45 @@ define(function (require, exports, module) {
     CommandManager.register(Strings.CMD_SHOW_SIDEBAR, Commands.SHOW_SIDEBAR, show);
     CommandManager.register(Strings.CMD_HIDE_SIDEBAR, Commands.HIDE_SIDEBAR, hide);
 
+    /**
+     * Programmatically resize the sidebar to the given width. Persists
+     * the new size so it is restored on reload, resyncs the drag handle,
+     * and fires `panelResizeEnd`.
+     *
+     * @param {number} width  Desired sidebar width in pixels
+     */
+    function resize(width) {
+        if (!$sidebar || !$sidebar.length) {
+            return;
+        }
+        width = Math.round(width);
+        $sidebar.width(width);
+        $(".content").css("left", width);
+        Resizer.resyncSizer($sidebar);
+        var sidebarPrefs = PreferencesManager.getViewState("sidebar") || {};
+        sidebarPrefs.size = width;
+        PreferencesManager.setViewState("sidebar", sidebarPrefs);
+        $sidebar.trigger("panelResizeEnd", [width]);
+    }
+
+    /**
+     * Get the current sidebar width in pixels. Returns the CSS width
+     * even if the sidebar is hidden (so the value can be restored later).
+     *
+     * @return {number}
+     */
+    function getWidth() {
+        if (!$sidebar || !$sidebar.length) {
+            return 0;
+        }
+        return $sidebar.width();
+    }
+
     // Define public API
     exports.toggle      = toggle;
     exports.show        = show;
     exports.hide        = hide;
     exports.isVisible   = isVisible;
+    exports.resize      = resize;
+    exports.getWidth    = getWidth;
 });

src/view/SidebarTabs.js

@@ -37,8 +37,9 @@
  */
 define(function (require, exports, module) {
 
-    const AppInit          = require("utils/AppInit"),
-        EventDispatcher  = require("utils/EventDispatcher");
+    const AppInit              = require("utils/AppInit"),
+        EventDispatcher      = require("utils/EventDispatcher"),
+        PreferencesManager   = require("preferences/PreferencesManager");
 
     // --- Constants -----------------------------------------------------------
 
@@ -48,6 +49,16 @@ define(function (require, exports, module) {
      */
     const SIDEBAR_TAB_FILES = "sidebar-tab-files";
 
+    /**
+     * Preferred sidebar width (px) when a non-files tab (e.g. AI) is
+     * first activated. Applied once if the current width is narrower.
+     * @const {number}
+     */
+    const AI_TAB_GOOD_WIDTH = 370;
+
+    /** Preference key used to track whether the initial width bump has been applied. */
+    const PREF_AI_WIDTH_SET_INITIAL = "aiTabWidthSetInitial";
+
     // --- Events --------------------------------------------------------------
 
     /**
@@ -423,6 +434,17 @@ define(function (require, exports, module) {
 
         _applyTabVisibility();
 
+        // One-time sidebar width bump when switching to a non-files tab
+        if (id !== SIDEBAR_TAB_FILES && $sidebar && $sidebar.length) {
+            if (!PreferencesManager.getViewState(PREF_AI_WIDTH_SET_INITIAL)) {
+                const SidebarView = require("project/SidebarView");
+                if (SidebarView.getWidth() < AI_TAB_GOOD_WIDTH) {
+                    SidebarView.resize(AI_TAB_GOOD_WIDTH);
+                }
+                PreferencesManager.setViewState(PREF_AI_WIDTH_SET_INITIAL, true);
+            }
+        }
+
         if (previousTabId !== id) {
             exports.trigger(EVENT_TAB_CHANGED, id, previousTabId);
         }

test/spec/SidebarTabs-integ-test.js

@@ -18,16 +18,20 @@
  *
  */
 
-/*global describe, it, expect, beforeAll, afterAll, beforeEach, awaitsFor */
+/*global describe, it, expect, beforeAll, afterAll, beforeEach, awaitsFor, awaitsForDone, jsPromise */
 
 define(function (require, exports, module) {
 
     const SpecRunnerUtils = require("spec/SpecRunnerUtils");
 
     let SidebarTabs,
+        SidebarView,
+        CommandManager,
+        Commands,
         testWindow,
         brackets,
-        _$;
+        _$,
+        originalSidebarWidth;
 
     // Test tab constants
     const TEST_TAB_ID = "sidebar-tab-test";
@@ -39,23 +43,22 @@ define(function (require, exports, module) {
             testWindow = await SpecRunnerUtils.createTestWindowAndRun();
             brackets = testWindow.brackets;
             SidebarTabs = brackets.test.SidebarTabs;
+            SidebarView = brackets.test.SidebarView;
+            CommandManager = brackets.test.CommandManager;
+            Commands = brackets.test.Commands;
             _$ = testWindow.$;
+            originalSidebarWidth = SidebarView.getWidth();
         }, 30000);
 
         afterAll(async function () {
-            // Reset to files tab
+            // Reset to files tab and restore original sidebar width
             SidebarTabs.setActiveTab(SidebarTabs.SIDEBAR_TAB_FILES);
-
-            // Remove any test tabs that may still exist
-            const allTabs = SidebarTabs.getAllTabs();
-            allTabs.forEach(function (tab) {
-                if (tab.id !== SidebarTabs.SIDEBAR_TAB_FILES) {
-                    // Clear content first so removeTab succeeds
-                    // (skip tabs that have content - they belong to other extensions)
-                }
-            });
+            SidebarView.resize(originalSidebarWidth);
 
             SidebarTabs = null;
+            SidebarView = null;
+            CommandManager = null;
+            Commands = null;
             testWindow = null;
             brackets = null;
             _$ = null;
@@ -454,5 +457,85 @@ define(function (require, exports, module) {
                 expect($navTabBar.hasClass("has-tabs")).toBe(countAfterRemove >= 2);
             });
         });
+
+        describe("Show in File Tree command", function () {
+            const testProjectPath = SpecRunnerUtils.getTestPath("/spec/DocumentCommandHandlers-test-files");
+
+            beforeAll(async function () {
+                await SpecRunnerUtils.loadProjectInTestWindow(testProjectPath);
+            }, 30000);
+
+            afterAll(async function () {
+                // Close all files opened during these tests
+                await awaitsForDone(
+                    CommandManager.execute(Commands.FILE_CLOSE_ALL, { _forceClose: true }),
+                    "close all files"
+                );
+            }, 30000);
+
+            it("should switch to files tab when executed from a non-files tab", async function () {
+                // Open a file so handleShowInTree has an activeFile
+                await awaitsForDone(
+                    SpecRunnerUtils.openProjectFiles(["test.js"]),
+                    "open test file"
+                );
+
+                SidebarTabs.addTab(TEST_TAB_ID, "Test Tab", "fa-solid fa-flask");
+                SidebarTabs.setActiveTab(TEST_TAB_ID);
+                expect(SidebarTabs.getActiveTab()).toBe(TEST_TAB_ID);
+
+                await awaitsForDone(
+                    CommandManager.execute(Commands.NAVIGATE_SHOW_IN_FILE_TREE),
+                    "show in file tree"
+                );
+
+                expect(SidebarTabs.getActiveTab()).toBe(SidebarTabs.SIDEBAR_TAB_FILES);
+            });
+
+            it("should remain on files tab when already on files tab", async function () {
+                await awaitsForDone(
+                    SpecRunnerUtils.openProjectFiles(["test.js"]),
+                    "open test file"
+                );
+                expect(SidebarTabs.getActiveTab()).toBe(SidebarTabs.SIDEBAR_TAB_FILES);
+
+                await awaitsForDone(
+                    CommandManager.execute(Commands.NAVIGATE_SHOW_IN_FILE_TREE),
+                    "show in file tree"
+                );
+
+                expect(SidebarTabs.getActiveTab()).toBe(SidebarTabs.SIDEBAR_TAB_FILES);
+            });
+        });
+
+        describe("SidebarView resize", function () {
+            let SidebarView, originalWidth;
+
+            beforeAll(function () {
+                SidebarView = brackets.test.SidebarView;
+                originalWidth = SidebarView.getWidth();
+            });
+
+            afterAll(function () {
+                SidebarView.resize(originalWidth);
+            });
+
+            it("should change the sidebar width", function () {
+                SidebarView.resize(400);
+                expect(SidebarView.getWidth()).toBe(400);
+            });
+
+            it("should update the .content left offset", function () {
+                SidebarView.resize(350);
+                expect(parseInt(_$(".content").css("left"), 10)).toBe(350);
+            });
+
+            it("should persist the width in view state", function () {
+                const PreferencesManager = testWindow.brackets.test.PreferencesManager;
+                SidebarView.resize(380);
+                const prefs = PreferencesManager.getViewState("sidebar");
+                expect(prefs.size).toBe(380);
+            });
+        });
     });
 });