nx_coa_lib.nx

nx_coa_lib.nx -- F982: CHART OF ACCOUNTS + PERIOD CLOSE, on the sovereign ledger. nx_ledger deliberately has ONE balance convention (credits - debits, custodial sense) because a primitive should not guess. This is the layer that makes a balance INTERPRETABLE: it records what KIND each account is, and therefore which side is its NORMAL balance. asset, expense -> DEBIT-normal (natural balance = debits - credits) liability, equity, revenue -> CREDIT-normal (natural balance = credits - debits) So a funded bank account reads +$100 instead of -$100, without the ledger having to take sides. ★DATA-DRIVEN (rule 11): the type->side map is STORED, not hardcoded. Adding an account kind is a DATA write (coa_type_put), not a code change and not a recompile. ★FAIL-CLOSED (rule 26 analog): an account with no registered type, or a type with no registered side, does NOT silently default to a side -- coa_natural returns 0 (unknown) and writes nothing. Guessing a sign on money is how a balance sheet inverts silently. PERIOD CLOSE: closing a period appends a lock record. coa_post_ok REFUSES posting into a closed period. Locks are append-only like everything else -- a close is a fact, not a mutable flag. Closing is IDEMPOTENT (rule 10): closing an already-closed period is a no-op that still reports closed. license_tier: ORIGINAL No hw writes (Rule 26). LIB (no main).