nostr-addressable-event-dual-tag-query

Nostr Addressable Event Dual-Tag Query

Problem

When querying related events (comments, reactions, reposts, zaps) for Nostr addressable events (Kind 30000-39999), the query returns fewer or zero results even though an indexing service shows the correct count. This happens because addressable events can be referenced two ways, and different clients use different methods.

Context / Trigger Conditions

Use this skill when:

• Video/post shows comment count of 5, but comments modal says "No comments yet"
• REST API (like Funnelcake) returns correct engagement counts, but WebSocket queries return empty
• Working with NIP-22 comments (Kind 1111) on addressable events
• Working with NIP-25 reactions (Kind 7) on addressable events
• Working with NIP-18 reposts (Kind 6/16) on addressable events
• Any feature querying events that reference Kind 30000-39999 events

Root Cause

For addressable events (Kind 30000-39999, like Kind 34236 videos), related events can reference the target using either:

1. E tag: References by event ID (64-character hex)

   ["E", "abc123...def456", "", "author-pubkey"]
   

2. A tag: References by addressable identifier (kind:pubkey:d-tag)

   ["A", "34236:abc123...def456:my-video-id", "", "author-pubkey"]
   

Different Nostr clients and indexers use different conventions:

• Some always use E tags (event ID-based)
• Some prefer A tags for addressable events (following NIP-22 strictly)
• Some use both tags

If your app only queries by one tag type, you'll miss events tagged with the other.

Solution

1. Update Filter Class (if needed)

Ensure your Filter class supports uppercase A tag queries:

// In Filter class
List<String>? uppercaseA;  // Add this field

// In toJson()
if (uppercaseA != null) {
  data['#A'] = uppercaseA;
}

2. Query by BOTH Tags

When loading related events, run two parallel queries and merge results:

Future<List<Event>> loadRelatedEvents({
  required String eventId,
  required String? addressableId,  // Format: "kind:pubkey:d-tag"
}) async {
  // Query by E tag (event ID)
  final filterByE = Filter(
    kinds: [targetKind],
    uppercaseE: [eventId],
  );

  // If addressable ID available, also query by A tag
  if (addressableId != null && addressableId.isNotEmpty) {
    final filterByA = Filter(
      kinds: [targetKind],
      uppercaseA: [addressableId],
    );

    // Run both queries in parallel
    final results = await Future.wait([
      nostrClient.queryEvents([filterByE]),
      nostrClient.queryEvents([filterByA]),
    ]);

    // Merge and deduplicate by event ID
    final eventMap = <String, Event>{};
    for (final event in results[0]) {
      eventMap[event.id] = event;
    }
    for (final event in results[1]) {
      eventMap[event.id] = event;
    }

    return eventMap.values.toList();
  }

  return nostrClient.queryEvents([filterByE]);
}