nx_editstack_gate.nx

nx_editstack_gate.nx -- the gate for nx_editstack_lib (/compare/dcc DC1 and DC2). THE CLAIM UNDER TEST is the one no float DCC can make: replaying the operation log from the base reproduces the state BIT-IDENTICALLY, and re-evaluating a parameter at depth equals building the whole log again from scratch with that parameter. Both are asserted on a DIGEST OF THE STATE, never on a return code, because a leaking or no-op implementation answers identical return codes. ANTI-VACUITY IS EXPLICIT, in three places, because "replay equals live" is trivially true for a stack that does nothing at all: - the digest is proven to DISCRIMINATE (three different states must give three different digests); a constant digest function would otherwise pass every other tooth on this gate. - undo is proven to reach an EARLIER state, so replay cannot be a no-op: it must genuinely reset to the base and re-apply a PREFIX of the log. - re-evaluation is proven equal to an INDEPENDENTLY BUILT stack, not merely different from before. Every refusal cell is a gv_bite: it must fire on the bad input AND stay silent on the good one. 100% sovereign. No hardware writes (Rule 26). license_tier: ORIGINAL expect_exit: 0