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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+# Plain vector RAG against GraphRAG: is every supporting document in the context?
+
+corpus: 35 chunks (one document each); 9 questions; evidence = the documents that together hold every fact needed
+vector: Neo4jVectorStore, top-k chunks.  graph: link spans (cosine >= 0.80), walk <= 3 hops, keep the 6 best-ranked paths, take the chunks that stated their edges
+
+id  hops | vector k4 vector k8 | graph     chunks  | question
+Q1  1    | yes       yes       | yes       6       | Who leads the Fulfilment Team?
+Q2  2    | yes       yes       | yes       5       | Who leads the team that owns the Payments Gateway?
+Q3  2    | NO        NO        | yes       4       | Which team owns the root cause of INC-2041?
+Q4  3    | NO        yes       | yes       5       | Who does the leader of the team that owns the Payments Gateway report to?
+Q5  3    | NO        yes       | yes       4       | Where is the company that hosts the database behind the Ledger Service located?
+Q6  3    | NO        yes       | NO        5       | Who leads the teams that own the services the Checkout Service depends on?
+Q7  3    | NO        NO        | NO        5       | Which services stop working if the Orders Database goes down?
+Q8  2    | NO        NO        | yes       6       | Which incidents affected services that the Checkout Service depends on directly?
+Q9  3    | NO        NO        | yes       4       | Who leads the team that owns the service INC-2057 affected?
+
+complete evidence: vector k=4 2/9, vector k=8 5/9, graph 7/9 (graph context averaged 4.9 chunks; vector k=8 is always 8)
+  1-hop questions (1): vector k=4 1, vector k=8 1, graph 1
+  2-hop questions (3): vector k=4 1, vector k=8 1, graph 3
+  3-hop questions (5): vector k=4 0, vector k=8 3, graph 3
+
+--- what each retriever missed ---
+Q1  vector k=8 missing []   graph missing []
+Q2  vector k=8 missing []   graph missing []
+Q3  vector k=8 missing [db-orders]   graph missing []
+Q4  vector k=8 missing []   graph missing []
+Q5  vector k=8 missing []   graph missing []
+Q6  vector k=8 missing []   graph missing [team-payments]
+Q7  vector k=8 missing [svc-payments-gateway]   graph missing [svc-checkout, svc-payments-gateway]
+Q8  vector k=8 missing [inc-2057]   graph missing []
+Q9  vector k=8 missing [team-fulfilment, svc-inventory]   graph missing []