* fix(recall): cap entity fanout in graph expansion to prevent slow queries
On large banks, the entity co-occurrence self-join in _expand_combined()
produces massive intermediate row counts when seeds reference high-fanout
entities (e.g. an entity with 25K+ mentions). This causes recall latency
to degrade significantly.
Changes:
- Replace unbounded entity self-join with LATERAL per-entity cap
(graph_per_entity_limit, default 200), reducing intermediate rows
from potentially millions to at most num_entities * 200
- Add ORDER BY unit_id DESC in LATERAL subquery for deterministic
recency-biased sampling (rides the PK index, no extra sort)
- Add timeout fallback (graph_expansion_timeout, default 10s) that
drops entity expansion and falls back to semantic+causal only
- Add composite index (entity_id, unit_id) on unit_entities for
index-only scans in the LATERAL subquery
- Merge 3 unmerged migration heads into one
- Fix recall_perf.py dotenv override issue
Unlike the approach in #895, this does NOT filter out hub entities
entirely — all entities are kept but capped equally, preserving
retrieval quality for queries about frequently-mentioned entities.
Benchmarked on a 67K-unit bank (top entity = 25K mentions):
- retrieval_graph: 0.337s → 0.055s (84% faster)
- end-to-end recall: 0.912s → 0.519s (43% faster)
* fix(tests): fix broken test_combined_scoring and test_reranking_proof_count
- test_combined_scoring: replace MagicMock(spec=RetrievalResult) with real
dataclass instances — MagicMock attributes returned nested mocks that
failed on >= comparisons with int
- test_reranking_proof_count: remove deleted `embedding` param from
RetrievalResult constructor, use None for occurred_start/end to get
neutral recency (datetime.now gave recency=1.0 which boosted scores)
* refactor: rename config to link_expansion_ prefix, fix observation fanout
- Rename GRAPH_PER_ENTITY_LIMIT → LINK_EXPANSION_PER_ENTITY_LIMIT and
GRAPH_EXPANSION_TIMEOUT → LINK_EXPANSION_TIMEOUT to follow the
convention that these are specific to the link_expansion graph retriever
- Apply the same LATERAL per-entity cap to _expand_observations(), which
had the same unbounded self-join through unit_entities
* style: fix formatting in config.py
