Regression fox surfaced 2026-05-02:
Q: "what technology are currently or soon available which may
enable one person to reconstruct and understand some or a
portion of another persons thoughts or ideas without
speaking or sign language."
→ sqlite3.OperationalError: Expression tree is too large
(maximum depth 1000)
Root cause: the v1 of _search_titles (commit 0052845) chained N
``CASE WHEN ... THEN 1 ELSE 0 END + ...`` expressions for the
title_score column. Each CASE WHEN is multiple tree nodes; +-
chained N times exceeded SQLite's default 1000-depth bound on
question texts with ~30+ content tokens.
Fix: simplified SQL — OR-chain WHERE + ORDER BY LENGTH(title) ASC
+ LIMIT bumped 4x to compensate for the lost smart sorting. The
caller's post-filter (word-boundary stem-aware token-set
intersect) does the actual title-relevance ranking; SQL just
needs to surface enough candidates for the post-filter to grade.
Also: cap the OR-chain at MAX_TITLE_LIKE_TOKENS=24 so pathological
200-token queries don't cascade SQL expression growth even
defensively. Beyond ~24 tokens the post-filter is doing all the
work; extra LIKEs just inflate candidate sets without signal.
5 new tests in tests/test_query.py covering the regression at
unit / integration / functional layers:
- test_unit_search_titles_handles_long_question_without_crash
50-token query through _search_titles directly. Pre-fix raised
sqlite3.OperationalError; post-fix returns row list.
- test_unit_search_titles_handles_zero_tokens
Defensive: empty token list → empty result, no SQL executed.
- test_unit_search_titles_caps_or_chain_at_max_tokens
200-token pathological query — bounded by MAX_TITLE_LIKE_TOKENS,
doesn't crash.
- test_integration_query_completes_on_long_question
End-to-end query() with StubClient + long question completes
without the SQLite error. Pre-fix raised before reaching the
LLM call.
- test_functional_long_question_returns_sources
The neurotech doc (richest body match) appears in top-K despite
the long-question retrieval path.
Test_query.py: 35 → 40 passing. Full suite (excluding parallel
test_concepts churn from concepts/query.py rewrite): no other
regressions.
russell@unturf.com
faed58dd0a