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FA-27676 / HTTP ranges / Open access

A remote archive reader locates the central directory from a suffix range response: a signature inside the archive comment is not accepted as the end record · case 01

A remote archive reader locates the central directory from a suffix range response: a signature inside the archive comment is not accepted as the end record.

Verified by executionVariant 1 · 16 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The remote-zip-directory-comment-anchored-eocd decision uses import struct T=x['total'] want=min(T,x['suffix']) head='bytes=-%d'%want if want>0 else None data=bytes.fromhex(x['tail']) base=T-len(data) p=len(data)-22 while p>=0: if data[p:p+4]==b'PK\x05\x06': break p-=1 if p<0: return [head,None] disk,cddisk,n1,n2,size,off=struct.unpack_from('<HHHHII',data,p+4) if disk!=0 or cddisk!=0 or n1!=n2: return [head,None] eocd=base+p if off+size>eocd: return [head,None] if off>=base: return [head,['local',off-base,size]] return [head,['fetch','bytes=%d-%d'%(off,min(base,off+size)-1)]].

VERIFIED REPAIR

Apply the bounded decision exactly: import struct T=x['total'] want=min(T,x['suffix']) head='bytes=-%d'%want if want>0 else None data=bytes.fromhex(x['tail']) base=T-len(data) p=len(data)-22 while p>=0: if data[p:p+4]==b'PK\x05\x06' and p+22+int.from_bytes(data[p+20:p+22],'little')==len(data): break p-=1 if p<0: return [head,None] disk,cddisk,n1,n2,size,off=struct.unpack_from('<HHHHII',data,p+4) if disk!=0 or cddisk!=0 or n1!=n2: return [head,None] eocd=base+p if off+size>eocd: return [head,None] if off>=base: return [head,['local',off-base,size]] return [head,['fetch','bytes=%d-%d'%(off,min(base,off+size)-1)]]

Unsuccessful approach: The partial repair uses import struct T=x['total'] want=min(T,x['suffix']) head='bytes=-%d'%want if want>0 else None data=bytes.fromhex(x['tail']) base=T-len(data) p=len(data)-22 while p>=0: if data[p:p+4]==b'PK\x05\x06' and p+22+int.from_bytes(data[p+20:p+22],'little')<=len(data): break p-=1 if p<0: return [head,None] disk,cddisk,n1,n2,size,off=struct.unpack_from('<HHHHII',data,p+4) if disk!=0 or cddisk!=0 or n1!=n2: return [head,None] eocd=base+p if off+size>eocd: return [head,None] if off>=base: return [head,['local',off-base,size]] return [head,['fetch','bytes=%d-%d'%(off,min(base,off+size)-1)]], which still violates the stated contract.

Case contract

x has total representation length, requested suffix length and the hex bytes of the suffix response (the last min(total,suffix) bytes). Emit the suffix Range value (null when it would be zero bytes). Scan backward for the end record signature PK\x05\x06 whose little-endian comment length makes the 22-byte record plus comment end exactly at the tail end. Reject multi-disk archives (disk or directory disk nonzero, or differing entry counts) and a directory that extends past the end record. A directory starting inside the tail is ["local",tail-index,size]; otherwise request only the missing prefix before the tail as ["fetch",inclusive range]. Output [suffix-range,plan-or-null].

Why this case matters

Range responses combine representation identity, conditional requests, framing, and partial-object state.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    import struct
    T=x['total']
    want=min(T,x['suffix'])
    head='bytes=-%d'%want if want>0 else None
    data=bytes.fromhex(x['tail'])
    base=T-len(data)
    p=len(data)-22
    while p>=0:
        if data[p:p+4]==b'PK\x05\x06': break
        p-=1
    if p<0: return [head,None]
    disk,cddisk,n1,n2,size,off=struct.unpack_from('<HHHHII',data,p+4)
    if disk!=0 or cddisk!=0 or n1!=n2: return [head,None]
    eocd=base+p
    if off+size>eocd: return [head,None]
    if off>=base: return [head,['local',off-base,size]]
    return [head,['fetch','bytes=%d-%d'%(off,min(base,off+size)-1)]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('comment-anchored-eocd fixture 0', json.loads(json.dumps(solve({'suffix':64,'tail':'0101010101010101010101010101010101010101434343434343434343434343434343434343504b0506000000000100010012000000140000000000','total':60}))), json.loads(json.dumps(['bytes=-60',['local',20,18]])))
check('comment-anchored-eocd fixture 1', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',['local',0,18]])))
check('comment-anchored-eocd fixture 2', json.loads(json.dumps(solve({'suffix':50,'tail':'43434343434343434343434343434343434300000000000000000000504b0506000000000100010012000000b60300000000','total':1000}))), json.loads(json.dumps(['bytes=-50',['local',0,18]])))
check('comment-anchored-eocd fixture 3', json.loads(json.dumps(solve({'suffix':30,'tail':'4343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-30',['fetch','bytes=960-969']])))
check('comment-anchored-eocd fixture 4', json.loads(json.dumps(solve({'suffix':22,'tail':'504b050600000000010001004e000000840300000000','total':1000}))), json.loads(json.dumps(['bytes=-22',['fetch','bytes=900-977']])))
check('comment-anchored-eocd fixture 5', json.loads(json.dumps(solve({'suffix':25,'tail':'504b050600000000010001004b000000840300000300616263','total':1000}))), json.loads(json.dumps(['bytes=-25',['fetch','bytes=900-974']])))
check('comment-anchored-eocd fixture 6', json.loads(json.dumps(solve({'suffix':80,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000880000001800504b05060000000001000100000000000000000000007a7a','total':200}))), json.loads(json.dumps(['bytes=-80',['local',0,18]])))
check('comment-anchored-eocd fixture 7', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 8', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506010001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 9', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100020012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 10', json.loads(json.dumps(solve({'suffix':100,'tail':'02020202020202020202020202020202020202020202020202020202020202020202020202020202504b05060000000001000100140000001e0000000000','total':62}))), json.loads(json.dumps(['bytes=-62',None])))
check('comment-anchored-eocd fixture 11', json.loads(json.dumps(solve({'suffix':30,'tail':'030303030303030303030303030303030303030303030303030303030303','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('comment-anchored-eocd fixture 12', json.loads(json.dumps(solve({'suffix':30,'tail':'000000000000000000000000000000000000000000000000000000000000','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('comment-anchored-eocd fixture 13', json.loads(json.dumps(solve({'suffix':64,'tail':'','total':0}))), json.loads(json.dumps([None,None])))
check('comment-anchored-eocd fixture 14', json.loads(json.dumps(solve({'suffix':64,'tail':'504b0506000000000000000000000000000000000000','total':22}))), json.loads(json.dumps(['bytes=-22',['local',0,0]])))
check('comment-anchored-eocd fixture 15', json.loads(json.dumps(solve({'suffix':32+N,'tail':"11"*10+"504b0506"+"00000000"+"01000100"+"0a000000"+(468-N).to_bytes(4,"little").hex()+(N).to_bytes(2,"little").hex()+"63"*N,'total':500}))), json.loads(json.dumps(["bytes=-%d"%(32+N),['local',0,10]])))
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
comment-anchored-eocd fixture 0['bytes=-60', ['local', 20, 18]]['bytes=-60', ['local', 20, 18]]Passed
comment-anchored-eocd fixture 1['bytes=-40', ['local', 0, 18]]['bytes=-40', ['local', 0, 18]]Passed
comment-anchored-eocd fixture 2['bytes=-50', ['local', 0, 18]]['bytes=-50', ['local', 0, 18]]Passed
comment-anchored-eocd fixture 3['bytes=-30', ['fetch', 'bytes=960-969']]['bytes=-30', ['fetch', 'bytes=960-969']]Passed
comment-anchored-eocd fixture 4['bytes=-22', ['fetch', 'bytes=900-977']]['bytes=-22', ['fetch', 'bytes=900-977']]Passed
comment-anchored-eocd fixture 5['bytes=-25', ['fetch', 'bytes=900-974']]['bytes=-25', ['fetch', 'bytes=900-974']]Passed
comment-anchored-eocd fixture 6['bytes=-80', ['fetch', 'bytes=0--1']]['bytes=-80', ['local', 0, 18]]Failed
comment-anchored-eocd fixture 7['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 8['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 9['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 10['bytes=-62', None]['bytes=-62', None]Passed
comment-anchored-eocd fixture 11['bytes=-30', None]['bytes=-30', None]Passed
comment-anchored-eocd fixture 12['bytes=-30', None]['bytes=-30', None]Passed
comment-anchored-eocd fixture 13[None, None][None, None]Passed
comment-anchored-eocd fixture 14['bytes=-22', ['local', 0, 0]]['bytes=-22', ['local', 0, 0]]Passed
comment-anchored-eocd fixture 15['bytes=-33', ['local', 0, 10]]['bytes=-33', ['local', 0, 10]]Passed

SHA-256 / 7c2b3db4f3bc5b564c2f3b33fac80cafc6f2517e150f7ae3faf11d21f4b69b7b

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    import struct
    T=x['total']
    want=min(T,x['suffix'])
    head='bytes=-%d'%want if want>0 else None
    data=bytes.fromhex(x['tail'])
    base=T-len(data)
    p=len(data)-22
    while p>=0:
        if data[p:p+4]==b'PK\x05\x06' and p+22+int.from_bytes(data[p+20:p+22],'little')<=len(data): break
        p-=1
    if p<0: return [head,None]
    disk,cddisk,n1,n2,size,off=struct.unpack_from('<HHHHII',data,p+4)
    if disk!=0 or cddisk!=0 or n1!=n2: return [head,None]
    eocd=base+p
    if off+size>eocd: return [head,None]
    if off>=base: return [head,['local',off-base,size]]
    return [head,['fetch','bytes=%d-%d'%(off,min(base,off+size)-1)]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('comment-anchored-eocd fixture 0', json.loads(json.dumps(solve({'suffix':64,'tail':'0101010101010101010101010101010101010101434343434343434343434343434343434343504b0506000000000100010012000000140000000000','total':60}))), json.loads(json.dumps(['bytes=-60',['local',20,18]])))
check('comment-anchored-eocd fixture 1', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',['local',0,18]])))
check('comment-anchored-eocd fixture 2', json.loads(json.dumps(solve({'suffix':50,'tail':'43434343434343434343434343434343434300000000000000000000504b0506000000000100010012000000b60300000000','total':1000}))), json.loads(json.dumps(['bytes=-50',['local',0,18]])))
check('comment-anchored-eocd fixture 3', json.loads(json.dumps(solve({'suffix':30,'tail':'4343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-30',['fetch','bytes=960-969']])))
check('comment-anchored-eocd fixture 4', json.loads(json.dumps(solve({'suffix':22,'tail':'504b050600000000010001004e000000840300000000','total':1000}))), json.loads(json.dumps(['bytes=-22',['fetch','bytes=900-977']])))
check('comment-anchored-eocd fixture 5', json.loads(json.dumps(solve({'suffix':25,'tail':'504b050600000000010001004b000000840300000300616263','total':1000}))), json.loads(json.dumps(['bytes=-25',['fetch','bytes=900-974']])))
check('comment-anchored-eocd fixture 6', json.loads(json.dumps(solve({'suffix':80,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000880000001800504b05060000000001000100000000000000000000007a7a','total':200}))), json.loads(json.dumps(['bytes=-80',['local',0,18]])))
check('comment-anchored-eocd fixture 7', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 8', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506010001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 9', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100020012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 10', json.loads(json.dumps(solve({'suffix':100,'tail':'02020202020202020202020202020202020202020202020202020202020202020202020202020202504b05060000000001000100140000001e0000000000','total':62}))), json.loads(json.dumps(['bytes=-62',None])))
check('comment-anchored-eocd fixture 11', json.loads(json.dumps(solve({'suffix':30,'tail':'030303030303030303030303030303030303030303030303030303030303','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('comment-anchored-eocd fixture 12', json.loads(json.dumps(solve({'suffix':30,'tail':'000000000000000000000000000000000000000000000000000000000000','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('comment-anchored-eocd fixture 13', json.loads(json.dumps(solve({'suffix':64,'tail':'','total':0}))), json.loads(json.dumps([None,None])))
check('comment-anchored-eocd fixture 14', json.loads(json.dumps(solve({'suffix':64,'tail':'504b0506000000000000000000000000000000000000','total':22}))), json.loads(json.dumps(['bytes=-22',['local',0,0]])))
check('comment-anchored-eocd fixture 15', json.loads(json.dumps(solve({'suffix':32+N,'tail':"11"*10+"504b0506"+"00000000"+"01000100"+"0a000000"+(468-N).to_bytes(4,"little").hex()+(N).to_bytes(2,"little").hex()+"63"*N,'total':500}))), json.loads(json.dumps(["bytes=-%d"%(32+N),['local',0,10]])))
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
comment-anchored-eocd fixture 0['bytes=-60', ['local', 20, 18]]['bytes=-60', ['local', 20, 18]]Passed
comment-anchored-eocd fixture 1['bytes=-40', ['local', 0, 18]]['bytes=-40', ['local', 0, 18]]Passed
comment-anchored-eocd fixture 2['bytes=-50', ['local', 0, 18]]['bytes=-50', ['local', 0, 18]]Passed
comment-anchored-eocd fixture 3['bytes=-30', ['fetch', 'bytes=960-969']]['bytes=-30', ['fetch', 'bytes=960-969']]Passed
comment-anchored-eocd fixture 4['bytes=-22', ['fetch', 'bytes=900-977']]['bytes=-22', ['fetch', 'bytes=900-977']]Passed
comment-anchored-eocd fixture 5['bytes=-25', ['fetch', 'bytes=900-974']]['bytes=-25', ['fetch', 'bytes=900-974']]Passed
comment-anchored-eocd fixture 6['bytes=-80', ['fetch', 'bytes=0--1']]['bytes=-80', ['local', 0, 18]]Failed
comment-anchored-eocd fixture 7['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 8['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 9['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 10['bytes=-62', None]['bytes=-62', None]Passed
comment-anchored-eocd fixture 11['bytes=-30', None]['bytes=-30', None]Passed
comment-anchored-eocd fixture 12['bytes=-30', None]['bytes=-30', None]Passed
comment-anchored-eocd fixture 13[None, None][None, None]Passed
comment-anchored-eocd fixture 14['bytes=-22', ['local', 0, 0]]['bytes=-22', ['local', 0, 0]]Passed
comment-anchored-eocd fixture 15['bytes=-33', ['local', 0, 10]]['bytes=-33', ['local', 0, 10]]Passed

SHA-256 / f44f698668755742673c631e70dc0da8fe27623ccae7abdbccc89a7807b6dce7

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    import struct
    T=x['total']
    want=min(T,x['suffix'])
    head='bytes=-%d'%want if want>0 else None
    data=bytes.fromhex(x['tail'])
    base=T-len(data)
    p=len(data)-22
    while p>=0:
        if data[p:p+4]==b'PK\x05\x06' and p+22+int.from_bytes(data[p+20:p+22],'little')==len(data): break
        p-=1
    if p<0: return [head,None]
    disk,cddisk,n1,n2,size,off=struct.unpack_from('<HHHHII',data,p+4)
    if disk!=0 or cddisk!=0 or n1!=n2: return [head,None]
    eocd=base+p
    if off+size>eocd: return [head,None]
    if off>=base: return [head,['local',off-base,size]]
    return [head,['fetch','bytes=%d-%d'%(off,min(base,off+size)-1)]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('comment-anchored-eocd fixture 0', json.loads(json.dumps(solve({'suffix':64,'tail':'0101010101010101010101010101010101010101434343434343434343434343434343434343504b0506000000000100010012000000140000000000','total':60}))), json.loads(json.dumps(['bytes=-60',['local',20,18]])))
check('comment-anchored-eocd fixture 1', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',['local',0,18]])))
check('comment-anchored-eocd fixture 2', json.loads(json.dumps(solve({'suffix':50,'tail':'43434343434343434343434343434343434300000000000000000000504b0506000000000100010012000000b60300000000','total':1000}))), json.loads(json.dumps(['bytes=-50',['local',0,18]])))
check('comment-anchored-eocd fixture 3', json.loads(json.dumps(solve({'suffix':30,'tail':'4343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-30',['fetch','bytes=960-969']])))
check('comment-anchored-eocd fixture 4', json.loads(json.dumps(solve({'suffix':22,'tail':'504b050600000000010001004e000000840300000000','total':1000}))), json.loads(json.dumps(['bytes=-22',['fetch','bytes=900-977']])))
check('comment-anchored-eocd fixture 5', json.loads(json.dumps(solve({'suffix':25,'tail':'504b050600000000010001004b000000840300000300616263','total':1000}))), json.loads(json.dumps(['bytes=-25',['fetch','bytes=900-974']])))
check('comment-anchored-eocd fixture 6', json.loads(json.dumps(solve({'suffix':80,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000880000001800504b05060000000001000100000000000000000000007a7a','total':200}))), json.loads(json.dumps(['bytes=-80',['local',0,18]])))
check('comment-anchored-eocd fixture 7', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 8', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506010001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 9', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100020012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('comment-anchored-eocd fixture 10', json.loads(json.dumps(solve({'suffix':100,'tail':'02020202020202020202020202020202020202020202020202020202020202020202020202020202504b05060000000001000100140000001e0000000000','total':62}))), json.loads(json.dumps(['bytes=-62',None])))
check('comment-anchored-eocd fixture 11', json.loads(json.dumps(solve({'suffix':30,'tail':'030303030303030303030303030303030303030303030303030303030303','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('comment-anchored-eocd fixture 12', json.loads(json.dumps(solve({'suffix':30,'tail':'000000000000000000000000000000000000000000000000000000000000','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('comment-anchored-eocd fixture 13', json.loads(json.dumps(solve({'suffix':64,'tail':'','total':0}))), json.loads(json.dumps([None,None])))
check('comment-anchored-eocd fixture 14', json.loads(json.dumps(solve({'suffix':64,'tail':'504b0506000000000000000000000000000000000000','total':22}))), json.loads(json.dumps(['bytes=-22',['local',0,0]])))
check('comment-anchored-eocd fixture 15', json.loads(json.dumps(solve({'suffix':32+N,'tail':"11"*10+"504b0506"+"00000000"+"01000100"+"0a000000"+(468-N).to_bytes(4,"little").hex()+(N).to_bytes(2,"little").hex()+"63"*N,'total':500}))), json.loads(json.dumps(["bytes=-%d"%(32+N),['local',0,10]])))
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
comment-anchored-eocd fixture 0['bytes=-60', ['local', 20, 18]]['bytes=-60', ['local', 20, 18]]Passed
comment-anchored-eocd fixture 1['bytes=-40', ['local', 0, 18]]['bytes=-40', ['local', 0, 18]]Passed
comment-anchored-eocd fixture 2['bytes=-50', ['local', 0, 18]]['bytes=-50', ['local', 0, 18]]Passed
comment-anchored-eocd fixture 3['bytes=-30', ['fetch', 'bytes=960-969']]['bytes=-30', ['fetch', 'bytes=960-969']]Passed
comment-anchored-eocd fixture 4['bytes=-22', ['fetch', 'bytes=900-977']]['bytes=-22', ['fetch', 'bytes=900-977']]Passed
comment-anchored-eocd fixture 5['bytes=-25', ['fetch', 'bytes=900-974']]['bytes=-25', ['fetch', 'bytes=900-974']]Passed
comment-anchored-eocd fixture 6['bytes=-80', ['local', 0, 18]]['bytes=-80', ['local', 0, 18]]Passed
comment-anchored-eocd fixture 7['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 8['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 9['bytes=-40', None]['bytes=-40', None]Passed
comment-anchored-eocd fixture 10['bytes=-62', None]['bytes=-62', None]Passed
comment-anchored-eocd fixture 11['bytes=-30', None]['bytes=-30', None]Passed
comment-anchored-eocd fixture 12['bytes=-30', None]['bytes=-30', None]Passed
comment-anchored-eocd fixture 13[None, None][None, None]Passed
comment-anchored-eocd fixture 14['bytes=-22', ['local', 0, 0]]['bytes=-22', ['local', 0, 0]]Passed
comment-anchored-eocd fixture 15['bytes=-33', ['local', 0, 10]]['bytes=-33', ['local', 0, 10]]Passed

SHA-256 / d3514885e8b4e03ffa02f823044cdc4deed3cab01e7b783bdfcf72bf09533578

Verification & scope

Deterministic simplified range service, with stipulated local policies and already parsed trusted inputs; not a complete HTTP implementation. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:41:27.137113+00:00.

Case digest / ba7cce8aa84439161990ca002b572c92df1732d035eec52d39b02c026c4afece