Closes the lazy-anchor failure class fox surfaced in feedback-3
(2026-05-01) on "who is homer simpson's boss?":
Claim: "Homer Simpson's boss is Mr. Burns."
Cited span: voice-actor / Castellaneta bio prose
Pre-warrant: pointer-linked, source-role allowed, coverage passes
Post-warrant: WARRANT_MISSING violation, audit_mode capped at HYBRID
Pointer verification != warrant verification. A pointer resolves to
a span; a warrant requires the span to actually contain the claim's
named answer entity.
Adds aborist/qa/warrant.py:
- is_relation_question(q) — regex shape detector for "who is X's Y?",
"who is supermans girlfriend?", "who founded Z?", "boss of X" etc.
- extract_answer_anchors(claim) — multi-word proper nouns ("Mr.
Burns", "Lois Lane") with possessive 's stripping; solo-cap
fallback that skips sentence-starter false positives
- warrant_check(claim, spans) — at-least-one-anchor lexical match;
vacuous-pass when claim has no proper-noun anchor
Wired into verify_claim_lattice via new params (question,
warrant_check_enabled). Per-claim WARRANT_MISSING violations cap
audit_mode at HYBRID using the same demote pattern as
lazy_anchor_demoted. CLI renders " · warrant missing" tail when
violations present so the failure mode is legible without scanning
the violations array.
Policy field claim_lattice_warrant_check_enabled added to
DEFAULT_POLICY / DEFAULT_QUERY_POLICY and the verifier-policy hash
field set so changes bump verifier_policy_hash.
Hard or soft? Per CLAUDE.md "Soft hash vs hard hash":
substring/lexical = hard. Output is binary (warrant present or not),
violations enter the proof path through violations[] alongside
SOURCE_ROLE_BLOCKED and CITATION_MISMATCH.
Deferred (follow-on commits):
- full RELATION_PATTERNS table with relation-noun aliases
- two-hop bridge detection ("X founded Y" + "Y is Z" -> "X is Z")
- retrieval expansion for relation questions
Tests: 16 new unit tests in tests/test_warrant.py covering
is_relation_question, extract_answer_anchors, warrant_check
(happy path, lazy-anchor case, vacuous-pass, case-insensitive,
empty inputs). Full suite: 523 passed, 21 skipped.
russell@unturf.com
38d95dd21b