FAILURE MAP
← Case archive

FA-27706 / HTTP ranges / Open access

A remote archive reader locates the central directory from a suffix range response: the follow-up range stops before bytes already present in the tail · case 01

A remote archive reader locates the central directory from a suffix range response: the follow-up range stops before bytes already present in the tail.

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

ROOT CAUSE

The remote-zip-directory-fetch-missing-prefix 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' 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,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))]], 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' 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,off+size-1)]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fetch-missing-prefix fixture 0', json.loads(json.dumps(solve({'suffix':64,'tail':'0101010101010101010101010101010101010101434343434343434343434343434343434343504b0506000000000100010012000000140000000000','total':60}))), json.loads(json.dumps(['bytes=-60',['local',20,18]])))
check('fetch-missing-prefix fixture 1', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',['local',0,18]])))
check('fetch-missing-prefix fixture 2', json.loads(json.dumps(solve({'suffix':50,'tail':'43434343434343434343434343434343434300000000000000000000504b0506000000000100010012000000b60300000000','total':1000}))), json.loads(json.dumps(['bytes=-50',['local',0,18]])))
check('fetch-missing-prefix fixture 3', json.loads(json.dumps(solve({'suffix':30,'tail':'4343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-30',['fetch','bytes=960-969']])))
check('fetch-missing-prefix fixture 4', json.loads(json.dumps(solve({'suffix':22,'tail':'504b050600000000010001004e000000840300000000','total':1000}))), json.loads(json.dumps(['bytes=-22',['fetch','bytes=900-977']])))
check('fetch-missing-prefix fixture 5', json.loads(json.dumps(solve({'suffix':25,'tail':'504b050600000000010001004b000000840300000300616263','total':1000}))), json.loads(json.dumps(['bytes=-25',['fetch','bytes=900-974']])))
check('fetch-missing-prefix fixture 6', json.loads(json.dumps(solve({'suffix':80,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000880000001800504b05060000000001000100000000000000000000007a7a','total':200}))), json.loads(json.dumps(['bytes=-80',['local',0,18]])))
check('fetch-missing-prefix fixture 7', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 8', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506010001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 9', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100020012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 10', json.loads(json.dumps(solve({'suffix':100,'tail':'02020202020202020202020202020202020202020202020202020202020202020202020202020202504b05060000000001000100140000001e0000000000','total':62}))), json.loads(json.dumps(['bytes=-62',None])))
check('fetch-missing-prefix fixture 11', json.loads(json.dumps(solve({'suffix':30,'tail':'030303030303030303030303030303030303030303030303030303030303','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('fetch-missing-prefix fixture 12', json.loads(json.dumps(solve({'suffix':30,'tail':'000000000000000000000000000000000000000000000000000000000000','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('fetch-missing-prefix fixture 13', json.loads(json.dumps(solve({'suffix':64,'tail':'','total':0}))), json.loads(json.dumps([None,None])))
check('fetch-missing-prefix fixture 14', json.loads(json.dumps(solve({'suffix':64,'tail':'504b0506000000000000000000000000000000000000','total':22}))), json.loads(json.dumps(['bytes=-22',['local',0,0]])))
check('fetch-missing-prefix 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
fetch-missing-prefix fixture 0['bytes=-60', ['local', 20, 18]]['bytes=-60', ['local', 20, 18]]Passed
fetch-missing-prefix fixture 1['bytes=-40', ['local', 0, 18]]['bytes=-40', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 2['bytes=-50', ['local', 0, 18]]['bytes=-50', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 3['bytes=-30', ['fetch', 'bytes=960-977']]['bytes=-30', ['fetch', 'bytes=960-969']]Failed
fetch-missing-prefix fixture 4['bytes=-22', ['fetch', 'bytes=900-977']]['bytes=-22', ['fetch', 'bytes=900-977']]Passed
fetch-missing-prefix fixture 5['bytes=-25', ['fetch', 'bytes=900-974']]['bytes=-25', ['fetch', 'bytes=900-974']]Passed
fetch-missing-prefix fixture 6['bytes=-80', ['local', 0, 18]]['bytes=-80', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 7['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 8['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 9['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 10['bytes=-62', None]['bytes=-62', None]Passed
fetch-missing-prefix fixture 11['bytes=-30', None]['bytes=-30', None]Passed
fetch-missing-prefix fixture 12['bytes=-30', None]['bytes=-30', None]Passed
fetch-missing-prefix fixture 13[None, None][None, None]Passed
fetch-missing-prefix fixture 14['bytes=-22', ['local', 0, 0]]['bytes=-22', ['local', 0, 0]]Passed
fetch-missing-prefix fixture 15['bytes=-33', ['local', 0, 10]]['bytes=-33', ['local', 0, 10]]Passed

SHA-256 / 636420ff71eed33a2014cd434e5ea218ff78d63dbdb8ff5ebfe6ef43043e362c

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))]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fetch-missing-prefix fixture 0', json.loads(json.dumps(solve({'suffix':64,'tail':'0101010101010101010101010101010101010101434343434343434343434343434343434343504b0506000000000100010012000000140000000000','total':60}))), json.loads(json.dumps(['bytes=-60',['local',20,18]])))
check('fetch-missing-prefix fixture 1', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',['local',0,18]])))
check('fetch-missing-prefix fixture 2', json.loads(json.dumps(solve({'suffix':50,'tail':'43434343434343434343434343434343434300000000000000000000504b0506000000000100010012000000b60300000000','total':1000}))), json.loads(json.dumps(['bytes=-50',['local',0,18]])))
check('fetch-missing-prefix fixture 3', json.loads(json.dumps(solve({'suffix':30,'tail':'4343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-30',['fetch','bytes=960-969']])))
check('fetch-missing-prefix fixture 4', json.loads(json.dumps(solve({'suffix':22,'tail':'504b050600000000010001004e000000840300000000','total':1000}))), json.loads(json.dumps(['bytes=-22',['fetch','bytes=900-977']])))
check('fetch-missing-prefix fixture 5', json.loads(json.dumps(solve({'suffix':25,'tail':'504b050600000000010001004b000000840300000300616263','total':1000}))), json.loads(json.dumps(['bytes=-25',['fetch','bytes=900-974']])))
check('fetch-missing-prefix fixture 6', json.loads(json.dumps(solve({'suffix':80,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000880000001800504b05060000000001000100000000000000000000007a7a','total':200}))), json.loads(json.dumps(['bytes=-80',['local',0,18]])))
check('fetch-missing-prefix fixture 7', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 8', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506010001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 9', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100020012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 10', json.loads(json.dumps(solve({'suffix':100,'tail':'02020202020202020202020202020202020202020202020202020202020202020202020202020202504b05060000000001000100140000001e0000000000','total':62}))), json.loads(json.dumps(['bytes=-62',None])))
check('fetch-missing-prefix fixture 11', json.loads(json.dumps(solve({'suffix':30,'tail':'030303030303030303030303030303030303030303030303030303030303','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('fetch-missing-prefix fixture 12', json.loads(json.dumps(solve({'suffix':30,'tail':'000000000000000000000000000000000000000000000000000000000000','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('fetch-missing-prefix fixture 13', json.loads(json.dumps(solve({'suffix':64,'tail':'','total':0}))), json.loads(json.dumps([None,None])))
check('fetch-missing-prefix fixture 14', json.loads(json.dumps(solve({'suffix':64,'tail':'504b0506000000000000000000000000000000000000','total':22}))), json.loads(json.dumps(['bytes=-22',['local',0,0]])))
check('fetch-missing-prefix 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
fetch-missing-prefix fixture 0['bytes=-60', ['local', 20, 18]]['bytes=-60', ['local', 20, 18]]Passed
fetch-missing-prefix fixture 1['bytes=-40', ['local', 0, 18]]['bytes=-40', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 2['bytes=-50', ['local', 0, 18]]['bytes=-50', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 3['bytes=-30', ['fetch', 'bytes=960-970']]['bytes=-30', ['fetch', 'bytes=960-969']]Failed
fetch-missing-prefix fixture 4['bytes=-22', ['fetch', 'bytes=900-978']]['bytes=-22', ['fetch', 'bytes=900-977']]Failed
fetch-missing-prefix fixture 5['bytes=-25', ['fetch', 'bytes=900-975']]['bytes=-25', ['fetch', 'bytes=900-974']]Failed
fetch-missing-prefix fixture 6['bytes=-80', ['local', 0, 18]]['bytes=-80', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 7['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 8['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 9['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 10['bytes=-62', None]['bytes=-62', None]Passed
fetch-missing-prefix fixture 11['bytes=-30', None]['bytes=-30', None]Passed
fetch-missing-prefix fixture 12['bytes=-30', None]['bytes=-30', None]Passed
fetch-missing-prefix fixture 13[None, None][None, None]Passed
fetch-missing-prefix fixture 14['bytes=-22', ['local', 0, 0]]['bytes=-22', ['local', 0, 0]]Passed
fetch-missing-prefix fixture 15['bytes=-33', ['local', 0, 10]]['bytes=-33', ['local', 0, 10]]Passed

SHA-256 / b1e509282ac4d8164515ec6a0ff6fb8fa173aa9a3a6cb7d14ed4c7efa81dae0d

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('fetch-missing-prefix fixture 0', json.loads(json.dumps(solve({'suffix':64,'tail':'0101010101010101010101010101010101010101434343434343434343434343434343434343504b0506000000000100010012000000140000000000','total':60}))), json.loads(json.dumps(['bytes=-60',['local',20,18]])))
check('fetch-missing-prefix fixture 1', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',['local',0,18]])))
check('fetch-missing-prefix fixture 2', json.loads(json.dumps(solve({'suffix':50,'tail':'43434343434343434343434343434343434300000000000000000000504b0506000000000100010012000000b60300000000','total':1000}))), json.loads(json.dumps(['bytes=-50',['local',0,18]])))
check('fetch-missing-prefix fixture 3', json.loads(json.dumps(solve({'suffix':30,'tail':'4343434343434343504b0506000000000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-30',['fetch','bytes=960-969']])))
check('fetch-missing-prefix fixture 4', json.loads(json.dumps(solve({'suffix':22,'tail':'504b050600000000010001004e000000840300000000','total':1000}))), json.loads(json.dumps(['bytes=-22',['fetch','bytes=900-977']])))
check('fetch-missing-prefix fixture 5', json.loads(json.dumps(solve({'suffix':25,'tail':'504b050600000000010001004b000000840300000300616263','total':1000}))), json.loads(json.dumps(['bytes=-25',['fetch','bytes=900-974']])))
check('fetch-missing-prefix fixture 6', json.loads(json.dumps(solve({'suffix':80,'tail':'434343434343434343434343434343434343504b0506000000000100010012000000880000001800504b05060000000001000100000000000000000000007a7a','total':200}))), json.loads(json.dumps(['bytes=-80',['local',0,18]])))
check('fetch-missing-prefix fixture 7', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 8', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506010001000100010012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 9', json.loads(json.dumps(solve({'suffix':40,'tail':'434343434343434343434343434343434343504b0506000000000100020012000000c00300000000','total':1000}))), json.loads(json.dumps(['bytes=-40',None])))
check('fetch-missing-prefix fixture 10', json.loads(json.dumps(solve({'suffix':100,'tail':'02020202020202020202020202020202020202020202020202020202020202020202020202020202504b05060000000001000100140000001e0000000000','total':62}))), json.loads(json.dumps(['bytes=-62',None])))
check('fetch-missing-prefix fixture 11', json.loads(json.dumps(solve({'suffix':30,'tail':'030303030303030303030303030303030303030303030303030303030303','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('fetch-missing-prefix fixture 12', json.loads(json.dumps(solve({'suffix':30,'tail':'000000000000000000000000000000000000000000000000000000000000','total':30}))), json.loads(json.dumps(['bytes=-30',None])))
check('fetch-missing-prefix fixture 13', json.loads(json.dumps(solve({'suffix':64,'tail':'','total':0}))), json.loads(json.dumps([None,None])))
check('fetch-missing-prefix fixture 14', json.loads(json.dumps(solve({'suffix':64,'tail':'504b0506000000000000000000000000000000000000','total':22}))), json.loads(json.dumps(['bytes=-22',['local',0,0]])))
check('fetch-missing-prefix 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
fetch-missing-prefix fixture 0['bytes=-60', ['local', 20, 18]]['bytes=-60', ['local', 20, 18]]Passed
fetch-missing-prefix fixture 1['bytes=-40', ['local', 0, 18]]['bytes=-40', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 2['bytes=-50', ['local', 0, 18]]['bytes=-50', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 3['bytes=-30', ['fetch', 'bytes=960-969']]['bytes=-30', ['fetch', 'bytes=960-969']]Passed
fetch-missing-prefix fixture 4['bytes=-22', ['fetch', 'bytes=900-977']]['bytes=-22', ['fetch', 'bytes=900-977']]Passed
fetch-missing-prefix fixture 5['bytes=-25', ['fetch', 'bytes=900-974']]['bytes=-25', ['fetch', 'bytes=900-974']]Passed
fetch-missing-prefix fixture 6['bytes=-80', ['local', 0, 18]]['bytes=-80', ['local', 0, 18]]Passed
fetch-missing-prefix fixture 7['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 8['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 9['bytes=-40', None]['bytes=-40', None]Passed
fetch-missing-prefix fixture 10['bytes=-62', None]['bytes=-62', None]Passed
fetch-missing-prefix fixture 11['bytes=-30', None]['bytes=-30', None]Passed
fetch-missing-prefix fixture 12['bytes=-30', None]['bytes=-30', None]Passed
fetch-missing-prefix fixture 13[None, None][None, None]Passed
fetch-missing-prefix fixture 14['bytes=-22', ['local', 0, 0]]['bytes=-22', ['local', 0, 0]]Passed
fetch-missing-prefix fixture 15['bytes=-33', ['local', 0, 10]]['bytes=-33', ['local', 0, 10]]Passed

SHA-256 / e4349fbab6fb0468d461e27c530b209bb9e960f74fcf079abb4953b882394ee3

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 2026-09-29T14:41:27.523101+00:00.

Case digest / 98489f54aff64e286e55c5ea8195b4c927df7a8d917314cb097758d83576df95