feat: Correctly assign containers to new live folder tabs, b=no-bug, c=folders

src/zen/folders/ZenFolders.mjs

@@ -1709,10 +1709,8 @@ class nsZenFolders extends nsZenDOMOperatedFeature {
           continue;
         }
 
-        if (!itemVisible) {
-          if (!itemsToHide.includes(item)) {
-            itemsToHide.push(item);
-          }
+        if (!itemVisible && !itemsToHide.includes(item)) {
+          itemsToHide.push(item);
         }
       }
     }
@@ -1757,7 +1755,6 @@ class nsZenFolders extends nsZenDOMOperatedFeature {
     }
 
     // Cleanup
-    this.styleCleanup(itemsToHide);
     this.styleCleanup(selectedTabs);
   }
 

src/zen/live-folders/ZenLiveFoldersManager.sys.mjs

@@ -378,6 +378,14 @@ class nsZenLiveFoldersManager {
       }
     }
 
+    let userContextId = 0;
+    let space = folder.ownerGlobal.gZenWorkspaces.getWorkspaceFromId(
+      folder.getAttribute("zen-workspace-id")
+    );
+    if (space) {
+      userContextId = space.containerTabId || 0;
+    }
+
     // Only add the items that are not already in the folder and was not dismissed by the user
     const newItems = items
       .filter((item) => {
@@ -391,6 +399,7 @@ class nsZenLiveFoldersManager {
           skipAnimation: true,
           noInitialLabel: true,
           lazyTabTitle: item.title,
+          userContextId,
         });
         // createLazyBrowser can't be pinned by default
         this.window.gBrowser.pinTab(tab);