fix: Resolve duplicate interaction detection and add usernames

- Add processed_ids set to prevent duplicate inserts when a tweet is
  both a mention and a comment (same external_id)
- Enhance get_mentions() to fetch usernames via user expansions
- Update fetch_interactions to prefer username over numeric author_id

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

worker/tasks/fetch_interactions.py

@@ -45,6 +45,10 @@ def fetch_platform_interactions(platform: str):
     try:
         publisher = get_publisher(platform)
 
+        # Set para trackear external_ids procesados en esta ejecución
+        # Evita duplicados cuando un tweet es tanto mención como comentario
+        processed_ids = set()
+
         # Obtener menciones
         mentions = run_async(publisher.get_mentions())
         new_mentions = 0
@@ -52,17 +56,23 @@ def fetch_platform_interactions(platform: str):
         for mention in mentions:
             external_id = mention.get("id")
 
-            # Verificar si ya existe
+            # Verificar si ya existe en DB o fue procesado en esta ejecución
+            if external_id in processed_ids:
+                continue
+
             existing = db.query(Interaction).filter(
                 Interaction.external_id == external_id
             ).first()
 
             if not existing:
+                # Obtener username (preferir username sobre author_id)
+                author_username = mention.get("username") or mention.get("author_id", "unknown")
+
                 interaction = Interaction(
                     platform=platform,
                     interaction_type="mention",
                     external_id=external_id,
-                    author_username=mention.get("username", mention.get("author_id", "unknown")),
+                    author_username=author_username,
                     author_name=mention.get("name"),
                     content=mention.get("text", mention.get("message")),
                     interaction_at=datetime.fromisoformat(
@@ -70,6 +80,7 @@ def fetch_platform_interactions(platform: str):
                     ) if mention.get("created_at") else datetime.utcnow()
                 )
                 db.add(interaction)
+                processed_ids.add(external_id)
                 new_mentions += 1
 
         # Obtener comentarios de posts recientes
@@ -90,6 +101,10 @@ def fetch_platform_interactions(platform: str):
             for comment in comments:
                 external_id = comment.get("id")
 
+                # Verificar si ya fue procesado como mención o existe en DB
+                if external_id in processed_ids:
+                    continue
+
                 existing = db.query(Interaction).filter(
                     Interaction.external_id == external_id
                 ).first()
@@ -120,6 +135,7 @@ def fetch_platform_interactions(platform: str):
                         ) if comment.get("created_at") or comment.get("timestamp") or comment.get("created_time") else datetime.utcnow()
                     )
                     db.add(interaction)
+                    processed_ids.add(external_id)
                     new_comments += 1
 
         db.commit()