fix: enforce custom edge types for FalkorDB and BFS search

[david-morales]

Summary

• Fixes custom edge type enforcement when using FalkorDB as the graph backend
• When using schema-defined edge types (e.g., SPOUSE_OF, BORN_IN, DIRECTED), all relationships were being saved as RELATES_TO instead of the defined types
• Adds FalkorDB support for dynamic relationship types and complex attribute serialization
• NEW: Fixes BFS search to traverse custom edge types (was hardcoded to RELATES_TO only)

Problem

When defining custom edge types in the schema:

1. All edges were saved as RELATES_TO instead of the specified types like SPOUSE_OF, BORN_IN, etc.
2. BFS search only traversed RELATES_TO edges, ignoring custom types during multi-hop traversal

Root Causes

1. The LLM prompt allowed inventing arbitrary edge types
2. FalkorDB's bulk save query hardcoded :RELATES_TO in the Cypher MERGE
3. No backend validation to catch LLM-invented types
4. BFS search queries hardcoded [:RELATES_TO|MENTIONS*1..N] path traversal

Solution

1. Stricter LLM Prompt (extract_edges.py)

• Enforces exact fact_type_name values from the schema
• Requires RELATES_TO as fallback when no schema type matches
• Explicitly rejects invented types and modified names

2. Backend Safety Net (edge_operations.py)

• Adds strict type checking when custom edge_types are defined
• Converts any LLM-invented types not in schema to RELATES_TO
• Ensures 100% schema compliance

3. FalkorDB Dynamic Edge Types (bulk_utils.py)

• Groups edges by type and runs separate queries per type
• FalkorDB requires static relationship types in Cypher MERGE statements
• Also adds JSON serialization for complex attribute types (dict/list)

4. BFS Search Fix (search_utils.py)

• Use wildcard traversal [*1..N] instead of [:RELATES_TO|MENTIONS*1..N]
• Match any edge type [e {uuid: ...}] instead of [e:RELATES_TO {uuid: ...}]
• Enables multi-hop reasoning across all relationship types

5. Updated Test (test_edge_operations.py)

• Reflects new stricter behavior: unknown types convert to RELATES_TO

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BM25 Fulltext Search

• Add edge_types parameter to EdgeSearchConfig to specify which relationship types to search
• Modify edge_fulltext_search to query multiple relationship type indexes for FalkorDB
• Each edge type's fulltext index is queried and results are combined
• Defaults to ['RELATES_TO'] for backward compatibility

Files:

• graphiti_core/search/search_config.py - Added edge_types field
• graphiti_core/search/search_utils.py - Updated edge_fulltext_search
• graphiti_core/search/search.py - Pass edge_types from config
• graphiti_core/graph_queries.py - Added edge_type parameter
• graphiti_core/driver/search_interface/search_interface.py - Added edge_types to interface

Test: test_edge_fulltext_search_custom_edge_types

Note: Custom edge types must have fulltext indexes created for BM25 search to work.

Test plan

• All edge_operations unit tests pass (7/7)
• FalkorDB edge tests pass
• KUZU BFS tests pass
• Tested with real ingestion - 100% schema compliance achieved
• Evaluation shows ~5% improvement in path recall with BFS fix