Empirical 2026-05-01: query 'has oceania always been at war with east
asia' surfaced literal-geography articles (Oceania, Asia, Far East)
because BM25 scored each token independently — the diagnostic signal
'oceania always been at war' is a verbatim 5-token sequence, not a
distinct content token. The Nineteen Eighty-Four article had zero
title-token overlap with the question, so even when reached via FTS5
phrase MATCH it would be filtered out before rerank.
Fix is two parts:
(1) New phrase route in `_search_corpus`. For each n-gram extracted
from the question (n=6 score 100, n=5 score 90), run an FTS5
quoted-phrase MATCH and add hits to the candidate pool. n=4 was
tried and rejected: 'always been at war' matches generic war-history
articles too noisily. 5+ tokens trade recall for precision; most
allusions ('may the force be with you', 'winter is coming',
'to be or not to be') survive at length 5 or higher.
(2) New accept-path 4 in `_filter_by_title_relevance`. Phrase-route
hits bypass the title-token-overlap gate via `phrase_match_roots`
(set of document_roots that matched a phrase). Without this, the
1984 article would be retrieved by phrase MATCH and immediately
filtered out because its title 'Nineteen Eighty-Four' shares no
content tokens with the question.
Latent-bug fix as a side effect: `_search_corpus` previously returned
a bare list, and the caller did `getattr(hits, "_core_match_roots",
set())` to fish out a sidecar set — but the sidecar was never
attached, so the `core_match_roots` accept-path in
_filter_by_title_relevance silently received an empty set for an
unknown duration. The function now returns a tuple
`(hits, core_match_roots, phrase_match_roots, root_to_shard)` so
both routes are correctly threaded.
Live verification: post-fix query lands EVIDENCE-LINKED 1/1 with
Nineteen Eighty-Four cited and the model recognizing the Orwell
frame ('the passage describes a change in alliances...'). No
operator augmentation needed.
Bench expansion: 6 allusion-shape questions added under a new
'# allusion / reference frame' category for prevalence tracking.
docs/reference-frame-failure-class.md: investigation log capturing
the diagnosis + why phrase-pattern boost beats a hand-rolled
'Reference Frame Router' (allusions are long-tail; per-pattern code
rots; the corpus already knows — fix retrieval not add a new stage).
9 new unit tests in test_query.py covering _question_phrases shape
(no stopword strip, all-short-token-skip, dedup), _search_phrases
defensive paths (empty input, double-quote-bearing input), end-to-
end phrase surfacing on a synthetic corpus, and the accept-path 4
filter behavior. Full suite 649 passed.
russell@unturf.com
1b8677d3d5