feat: harden runtime readiness and session workflow

frontend/src/shell/DeleteConfirmDialog.tsx

@@ -3,18 +3,24 @@ import { Button } from "../components/ui/button";
 
 interface Props {
   open: boolean;
-  label: string;
+  labels?: string[];
+  /** Backward-compatible single-session label. */
+  label?: string;
   onOpenChange: (open: boolean) => void;
   onConfirm: () => void;
 }
 
-export function DeleteConfirmDialog({ open, label, onOpenChange, onConfirm }: Props) {
+export function DeleteConfirmDialog({ open, labels, label, onOpenChange, onConfirm }: Props) {
+  const targets = labels ?? (label ? [label] : []);
+  const description = targets.length > 1
+    ? `${targets.length} sessions will be permanently deleted, including all of their documents. This action cannot be undone.`
+    : `"${targets[0]}" will be permanently deleted, including all of its documents. This action cannot be undone.`;
   return (
     <Dialog open={open} onOpenChange={onOpenChange}>
       <DialogContent>
         <DialogHeader><DialogTitle>Delete permanently</DialogTitle></DialogHeader>
         <DialogDescription>
-          "{label}" will be permanently deleted, including all of its documents. This action cannot be undone.
+          {description}
         </DialogDescription>
         <DialogFooter>
           <Button type="button" variant="outline" size="sm" onClick={() => onOpenChange(false)}>Cancel</Button>