nx_codata_gate.nx

nx_codata_gate.nx -- R2+R3 of the NIST CODATA external-reference loop: the VERIFY + LIAR-KILL gate that closes it. Reads our registry (sci_constants.tsv) and, for the NIST reference, the SOVEREIGN content- addressed store (nx_seg_store, populated by nx_codata_ingest) -- NOT a TSV. Asserts EVERY constant agrees with NIST. The grade is COMPUTED here, never self-asserted. Reference read: ss_get("knowledge/store/codata-", "codata:<sym>") -> canonical record bytes -> canon_decode -> {value, trunc}. Comparison (robust): split each value into significand + exponent at 'e'. Exponents must match exactly. Significands: if NIST truncated (trunc=1, e.g. reduced Planck / molar gas), our value must START WITH NIST's shown digits; else it must EQUAL them. Honest scope -- parity on the numbers: matching NIST IS the achievement; we never claim to beat the reference. EXCEED is only on the sovereign meta-axes. LIAR-KILL: a baked neg-control proves the comparator can tell a wrong value from a right one BEFORE any verdict. Writes knowledge/status/codata_gate.log. license_tier: ORIGINAL