Three faults in the graph tool, all on the agent's path:
The store was cached on the tool, and the executor caches the tool for the
whole agent run -- so one pgvector pooled connection stayed checked out across
every LLM round trip of that run, minutes at a time, and enough concurrent
runs exhaust the pool. GraphRAGRetriever releases its store before falling
back for this reason. The tool now releases it at the end of each action.
It gated on GRAPHRAG_ENABLED where everything else asks graphrag_available(),
which also requires the pgvector store. Under any other vector store the graph
tables are not the ones the sources were ingested into, but the tool was still
offered and still queried Postgres.
Pages were labelled by hand rather than through labels_from_metadata, which
exists so citation labels match across retrievers. A page read by the tool and
the same chunk retrieved by internal_search are one document, and citations
key on (source, title) -- so the research agent gave that document two
citation numbers. The recorded doc also keeps the full chunk text now, so it
dedupes against the retriever's copy; only what the model reads is truncated.
A one-shot graph ranking diffuses over the whole neighbourhood; a question
whose answer sits two hops away is better served by following the edges. The
graph_search tool gives an agent search_entities, get_relationships and
read_entity_pages over its graph sources. On a multi-hop corpus where the
bridging entity is never named, answers went from 0/10 with classic vector
retrieval to 10/10 with the tool, end to end through /stream.
The tool has no setting of its own. It is offered exactly where the agent can
already search: agentic and research agents always, a classic agent only for
sources exposed as a search tool. A graph source left at prefetch is used for
ranking only.
Tests now pin GRAPHRAG_ENABLED to its shipped default, as CI has: with a dev
.env enabling it, every agent test's graph check read the developer's real
database and left a pool to it behind.
Alex