add scene toolbar tool

My project/Assets/Prefabs/Managers.meta

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My project/Assets/Prefabs/TF/Phone Art/Envrionment(Clone).prefab.meta

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My project/Assets/Resources/Scene Collections.meta

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My project/Assets/Resources/Scene Collections/NewSceneCollection.asset

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+  m_Script: {fileID: 11500000, guid: 9d12c215cf29fa446abc76913d213425, type: 3}
+  m_Name: NewSceneCollection
+  m_EditorClassIdentifier: Assembly-CSharp::EditorSceneCollection
+  collectionName: MainScenes
+  description: 
+  showInMainMenu: 1
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My project/Assets/Resources/Scene Collections/NewSceneCollection.asset.meta

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My project/Assets/_Scripts/Editor.meta

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My project/Assets/_Scripts/Editor/EditorToolbarSceneButton.cs

+using UnityEditor;
+using UnityEditor.Toolbars;
+using UnityEditor.SceneManagement;
+using UnityEngine;
+
+/// <summary>
+/// Adds a "Scenes" button to the Unity main toolbar.
+/// Clicking it opens a flat "Main Scenes" menu populated from whichever
+/// EditorSceneCollection has "Show In Main Menu" enabled.
+/// </summary>
+public static class EditorToolbarSceneButton
+{
+    // ─── Toolbar Registration ────────────────────────────────────────────────
+
+    [MainToolbarElement("Scenes Button", defaultDockPosition = MainToolbarDockPosition.Right)]
+    public static MainToolbarElement GetScenesButton()
+    {
+        Texture2D icon = EditorGUIUtility.IconContent("SceneAsset Icon").image as Texture2D;
+
+        return new MainToolbarButton(
+            new MainToolbarContent("Scenes", icon, "Open a scene from Main Scenes."),
+            OnOpenScenesMenu
+        );
+    }
+
+    // ─── Menu Construction ───────────────────────────────────────────────────
+
+    private static void OnOpenScenesMenu()
+    {
+        GenericMenu menu = new GenericMenu();
+
+        EditorSceneCollection mainCollection = FindMainCollection();
+
+        if (mainCollection == null)
+        {
+            menu.AddDisabledItem(new GUIContent("No collection has 'Show In Main Menu' enabled."));
+            menu.ShowAsContext();
+            return;
+        }
+
+        // ── Header ──────────────────────────────────────────────────────────
+        menu.AddDisabledItem(new GUIContent("Main Scenes"));
+        menu.AddSeparator("");
+
+        // ── Optional description ─────────────────────────────────────────────
+        if (!string.IsNullOrWhiteSpace(mainCollection.Description))
+        {
+            menu.AddDisabledItem(new GUIContent(mainCollection.Description));
+            menu.AddSeparator("");
+        }
+
+        // ── Individual scenes ────────────────────────────────────────────────
+        bool anyScenesAdded = false;
+
+        if (mainCollection.SceneAssets != null)
+        {
+            foreach (SceneAsset scene in mainCollection.SceneAssets)
+            {
+                if (scene == null) continue;
+
+                string scenePath = AssetDatabase.GetAssetPath(scene);
+                string sceneName = scene.name;
+
+                menu.AddItem(new GUIContent(sceneName), false, () => OpenScene(scenePath));
+                anyScenesAdded = true;
+            }
+        }
+
+        if (!anyScenesAdded)
+            menu.AddDisabledItem(new GUIContent("No scenes assigned to this collection."));
+
+        // ── Open All shortcut ────────────────────────────────────────────────
+        menu.AddSeparator("");
+        menu.AddItem(new GUIContent("Open All"), false, mainCollection.OpenAll);
+
+        menu.ShowAsContext();
+    }
+
+    // ─── Helpers ─────────────────────────────────────────────────────────────
+
+    /// <summary>
+    /// Finds the first EditorSceneCollection with ShowInMainMenu enabled.
+    /// Logs a warning if more than one is found.
+    /// </summary>
+    private static EditorSceneCollection FindMainCollection()
+    {
+        string[] guids = AssetDatabase.FindAssets("t:EditorSceneCollection");
+
+        EditorSceneCollection result = null;
+        int mainCount = 0;
+
+        foreach (string guid in guids)
+        {
+            string path = AssetDatabase.GUIDToAssetPath(guid);
+            var collection = AssetDatabase.LoadAssetAtPath<EditorSceneCollection>(path);
+
+            if (collection == null || !collection.ShowInMainMenu) continue;
+
+            result ??= collection;
+            mainCount++;
+        }
+
+        if (mainCount > 1)
+            Debug.LogWarning("[EditorToolbarSceneButton] More than one EditorSceneCollection has 'Show In Main Menu' enabled. Only the first one found will be used.");
+
+        return result;
+    }
+
+    /// <summary>
+    /// Opens a single scene. Prompts the user to save unsaved changes first.
+    /// </summary>
+    private static void OpenScene(string path)
+    {
+        if (EditorSceneManager.SaveCurrentModifiedScenesIfUserWantsTo())
+            EditorSceneManager.OpenScene(path, OpenSceneMode.Single);
+    }
+}
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My project/Assets/_Scripts/Editor/EditorToolbarSceneButton.cs.meta

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