Add graphrag-neo4j module: structured-output entity and relation extraction into a typed Neo4j graph with a vector index, multi-hop retrieval by span linking and variable-length Cypher paths, compared with plain vector RAG over the same 35 chunks and 9 questions (complete evidence 7/9 vs 5/9 at k=8); Testcontainers on neo4j:2026.10.1 and 5.26. The extraction step is a rule-based stand-in, not a language model.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01CifR2BE7PBvRy5hT8TS9oz
2026-10-26 02:03:40 +00:00
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+# Building the graph in Neo4j; names that are the same thing (STUB extraction)
+
+image    : neo4j:5-community
+server   : Neo4j Kernel 5.26.32 community
+
+--- vector indexes (one from Neo4jVectorStore for chunks, one of ours for entity names) ---
+chunk_embedding        on (:Chunk).embedding  ONLINE
+entity_name_embedding  on (:Entity).embedding  ONLINE
+
+--- A. exact-name matching only (no alias table, similarity merge off) ---
+entities: 28
+Payments Gateway : -[DEPENDS_ON]-> Ledger Service; -[HOSTED_ON]-> Arcadia Cloud; -[OWNED_BY]-> Payments Team; <-[DEPENDS_ON]- Checkout Service
+Card Gateway     : <-[AFFECTED]- INC-2060
+
+--- same-type name pairs by cosine of their embeddings, top 8 of 72 ---
+0.806  INCIDENT INC-2057  <->  INC-2060
+0.797  INCIDENT INC-2041  <->  INC-2057
+0.758  INCIDENT INC-2041  <->  INC-2060
+0.681  SYSTEM  Card Gateway  <->  Payments Gateway
+0.540  SYSTEM  Ledger Service  <->  Inventory Service
+0.535  TEAM    Storefront Team  <->  Platform Team
+0.530  TEAM    Core Data Team  <->  Platform Team
+0.519  SYSTEM  Inventory Service  <->  Checkout Service
+-- Card Gateway <-> Payments Gateway: cosine 0.681, rank 4
+
+--- what a similarity-only merge would do at each threshold ---
+threshold 0.90 -> 0 merges: 
+threshold 0.80 -> 1 merges: INC-2057 + INC-2060
+threshold 0.70 -> 3 merges: INC-2057 + INC-2060; INC-2041 + INC-2057; INC-2041 + INC-2060
+threshold 0.60 -> 4 merges: INC-2057 + INC-2060; INC-2041 + INC-2057; INC-2041 + INC-2060; Card Gateway + Payments Gateway
+
+--- B. plus a one-line alias table (Card Gateway = Payments Gateway) ---
+entities: 27
+Payments Gateway : -[DEPENDS_ON]-> Ledger Service; -[HOSTED_ON]-> Arcadia Cloud; -[OWNED_BY]-> Payments Team; <-[AFFECTED]- INC-2060; <-[DEPENDS_ON]- Checkout Service
+chunks: 35, MENTIONS edges: 54, dropped relations: 0
+
+--- relationships by type ---
+DEPENDS_ON   6
+OWNED_BY     6
+HOSTED_ON    5
+LED_BY       5
+REPORTS_TO   4
+AFFECTED     3
+CAUSED_BY    2
+LOCATED_IN   2