Check member badge identifier collisions

src/components/AddMemberDialog.tsx

@@ -228,6 +228,23 @@ export function AddMemberDialog({
       // Step 1: Create badge definition if needed
       if (newMembers.length > 0 && !hasBadge) {
         const badgeDTag = `${community.dTag}-member`;
+        const existingBadge = await nostr.query([{
+          kinds: [BADGE_DEFINITION_KIND],
+          authors: [user.pubkey],
+          '#d': [badgeDTag],
+          limit: 1,
+        }]);
+
+        if (existingBadge.length > 0) {
+          toast({
+            title: 'Member badge ID already in use',
+            description: 'This community needs a member badge, but that badge identifier already exists on your account.',
+            variant: 'destructive',
+          });
+          setIsPublishing(false);
+          return;
+        }
+
         const badgeTags: string[][] = [
           ['d', badgeDTag],
           ['name', 'Member'],

src/components/CreateCommunityDialog.tsx

@@ -185,6 +185,23 @@ export function CreateCommunityDialog({ open, onOpenChange, communityEvent, comm
       }
 
       const badgeDTag = `${effectiveSlug}-member`;
+      const existingBadge = await nostr.query([{
+        kinds: [BADGE_DEFINITION_KIND],
+        authors: [user.pubkey],
+        '#d': [badgeDTag],
+        limit: 1,
+      }]);
+
+      if (existingBadge.length > 0) {
+        toast({
+          title: 'Member badge ID already in use',
+          description: 'Choose a different community name so the member badge can be created safely.',
+          variant: 'destructive',
+        });
+        setIsPublishing(false);
+        return;
+      }
+
       const badgeEvent = await publishEvent({
         kind: BADGE_DEFINITION_KIND,
         content: '',