fix duplicate lexicons in read, dedupe nsids in gql builder

api/src/database/records.rs

···
 
         query_builder = query_builder.bind(limit as i64);
 
-        let records = query_builder.fetch_all(&self.pool).await?;
+        let mut records = query_builder.fetch_all(&self.pool).await?;
+
+        // Deduplicate lexicon records by URI (same URI can exist with different slice_uri values)
+        if is_lexicon {
+            let mut seen_uris = std::collections::HashSet::new();
+            records.retain(|record| seen_uris.insert(record.uri.clone()));
+        }
 
         // Only return cursor if we got a full page, indicating there might be more
         let cursor = if records.len() < limit as usize {

api/src/graphql/schema_builder.rs

···
     slice_uri: String,
 ) -> Result<Schema, String> {
     // Fetch all lexicons for this slice
-    let lexicons = database
+    let all_lexicons = database
         .get_lexicons_by_slice(&slice_uri)
         .await
         .map_err(|e| format!("Failed to load lexicons: {}", e))?;
+
+    // Deduplicate by NSID for schema building (keep most recent due to ORDER BY indexed_at DESC)
+    // This prevents duplicate type registration errors without hiding duplicates from users
+    let mut seen_nsids = std::collections::HashSet::new();
+    let lexicons: Vec<serde_json::Value> = all_lexicons
+        .into_iter()
+        .filter(|lexicon| {
+            if let Some(nsid) = lexicon.get("id").and_then(|n| n.as_str()) {
+                seen_nsids.insert(nsid.to_string())
+            } else {
+                true // Keep lexicons without an ID (will fail validation later)
+            }
+        })
+        .collect();
 
     // Build Query root type and collect all object types
     let mut query = Object::new("Query");