🔧 Fix Sample Knowledge Graphs Display Issue

✅ Problem solved:
• Fixed sample KGs not appearing as 'final' knowledge graphs
• Frontend requires window_index=None for final KGs to display
• Sample data was incorrectly setting window_index=0

🎯 Root cause:
• Frontend logic: is_final = (window_index is None && window_total is not None)
• Sample data was setting window_index=0 instead of None
• This caused KGs to not be recognized as 'final' graphs for display

⚡ Technical fixes:
1. backend/database/sample_data.py:
- Changed window_index=0 to window_index=None for new sample KGs
- Keeps window_total=1 to indicate processed final graph

2. backend/database/init_db.py:
- Added automatic migration to fix existing sample KGs
- Detects window_index=0 + window_total=1 pattern and fixes to None
- Runs on every database initialization for existing data

🚀 Expected result:
• Sample traces will now show their knowledge graphs in the UI
• 'Generate First Graph' button should disappear
• Users can immediately see and interact with sample KGs
• Automatic fix for existing HF Spaces data on next restart

backend/database/init_db.py

@@ -361,7 +361,45 @@ def init_database(reset=False, force=False):
             logger.warning(f"Failed to insert sample data (non-critical): {str(e)}")
             logger.info("Database initialization completed without sample data")
     else:
-        logger.info("Existing data found, skipping sample data insertion")
+        # Check and fix existing sample knowledge graphs if needed
+        logger.info("Existing data found, checking for sample data fixes...")
+        try:
+            from . import SessionLocal
+            from .models import KnowledgeGraph, Trace
+            
+            session = SessionLocal()
+            try:
+                # Find sample traces
+                sample_traces = session.query(Trace).filter(
+                    Trace.trace_source == "sample_data"
+                ).all()
+                
+                if sample_traces:
+                    # Find knowledge graphs with incorrect window_index
+                    trace_ids = [trace.trace_id for trace in sample_traces]
+                    broken_kgs = session.query(KnowledgeGraph).filter(
+                        KnowledgeGraph.trace_id.in_(trace_ids),
+                        KnowledgeGraph.window_index == 0,  # Should be None for final KGs
+                        KnowledgeGraph.window_total == 1
+                    ).all()
+                    
+                    if broken_kgs:
+                        logger.info(f"Found {len(broken_kgs)} sample KGs that need fixing (window_index=0 -> None)")
+                        for kg in broken_kgs:
+                            kg.window_index = None  # Fix to make it a final KG
+                        session.commit()
+                        logger.info(f"✅ Fixed {len(broken_kgs)} sample knowledge graphs to display as final KGs")
+                    else:
+                        logger.info("All sample knowledge graphs are correctly configured")
+                        
+            except Exception as e:
+                session.rollback()
+                logger.warning(f"Error checking sample data fixes: {str(e)}")
+            finally:
+                session.close()
+                
+        except Exception as e:
+            logger.warning(f"Failed to check sample data fixes (non-critical): {str(e)}")
     
     # Close connection
     conn.close()

backend/database/sample_data.py

@@ -585,8 +585,8 @@ def insert_sample_data(session, force_insert=False):
                         filename=kg_data["filename"],
                         graph_data=kg_data["graph_data"],
                         trace_id=trace_ids[trace_index],
-                        window_index=0,
-                        window_total=1,
+                        window_index=None,  # None for final KG
+                        window_total=1,     # Not None to indicate it's a processed final KG
                         is_original=True
                     )
                     results["knowledge_graphs_inserted"] += 1