nx_ledger_gate.nx

nx_ledger_gate.nx -- F981 INDEPENDENT GATE for the sovereign double-entry ledger. Imports the lib and proves its contract by BEHAVIOUR on a live seg-store plane. ★NON-VACUITY NOTE (stated plainly rather than dressed up): conservation is STRUCTURAL here -- one record carries BOTH legs (dr and cr), so a one-sided entry is INEXPRESSIBLE and a global "drift == 0" assertion would be a TAUTOLOGY. Asserting it alone would be fake rigor. So the measured tests are the ones that CAN fail: * per-account balances summed across every account must total 0 -- this cross-checks the per-account FILTER against global conservation; a broken match would break it. * exact expected deltas (not merely non-zero) -- a sign flip or a wrong field would fail. * every refusal path must refuse AND leave ZERO state change. All assertions are DELTAS against a pre-read baseline, so the gate is re-runnable on a plane that already holds history (append-only = prior runs persist by design). license_tier: ORIGINAL No hw writes (Rule 26). expect_exit: 0