nx_cite_lib.nx

nx_cite_lib.nx -- F993 CITE-OR-ABSTAIN: deterministic citation verification, the legal flagship. THE 2026 WALL (measured, not rhetorical): independent benchmarks show ~24% of graded legal answers cite or misapply law that does NOT support the claim, and every model tested fabricated at least one citation. The sovereign answer is not a better-behaved chatbot -- it is a VERIFIER that structurally cannot pass a citation whose quoted text is not BYTE-PRESENT in the cited source. No LLM sits in the trust path: a citation is verified by exact substring containment against a stored, content-addressed source, so a fabricated or subtly-altered quote is caught by construction. FAIL-CLOSED, three honest outcomes: CITED (1) the quote is an exact span of a real source -> show the source ABSTAIN_NO_SOURCE (-1) the cited source does not exist (the "made-up case" failure) ABSTAIN_NO_SPAN (-2) the source exists but the quote is not in it (fabricated/altered/empty) An empty quote is ABSTAIN, never CITED -- "the empty string is a substring of everything" is exactly the hole a fabricator would drive through, so it is closed explicitly. BYTE-EXACT is the honest floor. Normalization (whitespace collapse, case-fold, smart-quote unify) is a DECLARED follow-on, not silently applied -- a verifier that quietly normalizes can be tricked into accepting a materially altered quote, so the strict floor ships first and any loosening is opt-in. SCALE ENVELOPE (declared): cite_verify is O(source-length) substring scan per call (Rabin-Karp/KMP is the speed rung); source retrieval inherits the seg-store read cost (see the finance-spine scale note). DRY: composes nx_matter_lib (reg_put/reg_get/mt_field/canon_encode). license_tier: ORIGINAL LIB.