Two fan-out streams. Both bear directly on the ticket's "search
latency on real shards" headline finding.
## Lazy concept_relations loading
Phase 1 (migration memoization) cut SQLite executes 65% but warm-
cache wall barely moved. cProfile pinned the next hotspot:
synonym_expand 2.8 s × 2 calls + _load_token_idf 0.3 s. The eager
loader dumped all ~290 K concept_relations rows on first call —
the price of being able to answer ANY future question without
re-querying. Wrong tradeoff for single-query CLI use.
Refactored arborist/concepts/query.py:
- New _load_neighbors_for(shards_dir, tokens) — targeted
WHERE token IN (...) OR target IN (...) query. Returns just the
direct synonym neighborhood for the given tokens (~300 rows for
a typical 5-token question, vs 290 K for the full table).
- New _load_rivalry_rows(shards_dir) — process-wide cache of the
~2-row rivalry-relation set; near-zero cost.
- New _load_idf_for(shards_dir, tokens) — IDF only fetched when
expansion exceeds max_total (the cap). Most queries never reach
the truncation branch and skip IDF entirely.
- Per-token process-wide neighbor cache so multi-query bench scripts
don't re-query tokens already seen.
- synonym_expand and rivalry_excluded refactored to use the lazy
loaders. Eager _load_indices / _get_indices kept for any
back-compat caller; not used by hot paths.
- invalidate_cache() clears all three caches.
All 14 concept tests pass unchanged — the contract is preserved.
Re-profile of `who wrote virt-back?` against ~38 GB of real shards
(warm cache):
metric pre-fix post-Phase-1 post-lazy-concepts
wall_ms 14,500 13,400 9,300 (-36%)
search_ms 9,900 10,600 5,000 (-49%)
SQLite executes 10,623 3,687 3,708 ~same
synonym_expand 2,966 2,840 ~0 (lazy hit)
Search target was <5 s; we hit 5.0 s on the warm path. Cold cache
should drop further (the 290 K-row dump was disk-bound).
## Real-shard baseline artifact (Phase 2)
bench/scripts/real_shard_baseline.py — runs an 8-question fixture
through the full query() pipeline and emits:
- bench/results/real-shard-baseline.json (durable; commit_sha,
shards_fingerprint, per-query rows, summary)
- bench/results/real-shard-baseline.md (human-readable summary)
Question set in bench/fixtures/real-shard-baseline-v1.jsonl:
virt-back, France, Mac OS X, Linux, Microsoft, AMD/Intel
(rivalry path), and two canonical-projection cases (math + logic
preflight short-circuit).
First baseline run (commit e78814c plus this fan-out, BURN=1):
audit_mode n notes
STRICT 4 (virt-back, France, Mac OS X, Linux)
HYBRID 2 (Microsoft founder, AMD/Intel)
CANONICAL 2 (0.1+0.2, A IMPL B; <1 ms each)
wall median 4.1 s (range 0.6 ms – 7.2 s)
primary used 4 / 8
`who wrote virt-back?` lands at 6.3 s wall, audit STRICT, primary
source #1, cited evidence still includes a copyright footer
(reviewer's warrant-quality finding — deferred to follow-up ticket
since the latency fix was the gating concern).
Hard constraint preserved: baselines NEVER gate CI. The artifact
is for confirming a fix moved the needle, seeding ForkScore
comparisons, and noting findings worth tickets.
`make bench-real-shard` wires it. Honors ARBORIST_SHARDS_DIR.
## Test status
Full suite: 1306 passed, 36 skipped (no regressions from the
concept refactor; 14 concept tests cover the lazy/eager
equivalence).
