FA-26471 / HTTP ranges / Open access

Top-level range metadata is absent for multipart bodies · case 01

Top-level range metadata is absent for multipart bodies.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The multipart-no-top-content-range decision uses return [individual[0] if individual else None,individual].

VERIFIED REPAIR

Apply the bounded decision exactly: return [individual[0],[]] if parts==1 else [None,individual]

Unsuccessful approach: The partial repair uses return [None,individual], which still violates the stated contract.

Case contract

Return [top-content-range,part-ranges]. A singleton uses its individual range at top and no per-part list; multiple parts have null top and all per-part ranges.

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(parts, individual):
    return [individual[0] if individual else None,individual]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multipart-no-top-content-range fixture 0', solve(2,["a"+str(N),"b"]), [None,["a"+str(N),"b"]])
check('multipart-no-top-content-range fixture 1', solve(1,["a"+str(N)]), ["a"+str(N),[]])
check('multipart-no-top-content-range fixture 2', solve(0,[]), [None,[]])
check('multipart-no-top-content-range fixture 3', solve(3,["a","b","c"]), [None,["a","b","c"]])
check('multipart-no-top-content-range fixture 4', solve(1,[""]), ["",[]])
check('multipart-no-top-content-range fixture 5', solve(2,["a","a"]), [None,["a","a"]])
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 fixture	Actual	Expected	Outcome
multipart-no-top-content-range fixture 0	`['a1', ['a1', 'b']]`	`[None, ['a1', 'b']]`	Failed
multipart-no-top-content-range fixture 1	`['a1', ['a1']]`	`['a1', []]`	Failed
multipart-no-top-content-range fixture 2	`[None, []]`	`[None, []]`	Passed
multipart-no-top-content-range fixture 3	`['a', ['a', 'b', 'c']]`	`[None, ['a', 'b', 'c']]`	Failed
multipart-no-top-content-range fixture 4	`['', ['']]`	`['', []]`	Failed
multipart-no-top-content-range fixture 5	`['a', ['a', 'a']]`	`[None, ['a', 'a']]`	Failed

SHA-256 / e2065db715a75b947f0a9233222592e0db2a168dccf38fee7a35fc0466e9bc9c

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(parts, individual):
    return [None,individual]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multipart-no-top-content-range fixture 0', solve(2,["a"+str(N),"b"]), [None,["a"+str(N),"b"]])
check('multipart-no-top-content-range fixture 1', solve(1,["a"+str(N)]), ["a"+str(N),[]])
check('multipart-no-top-content-range fixture 2', solve(0,[]), [None,[]])
check('multipart-no-top-content-range fixture 3', solve(3,["a","b","c"]), [None,["a","b","c"]])
check('multipart-no-top-content-range fixture 4', solve(1,[""]), ["",[]])
check('multipart-no-top-content-range fixture 5', solve(2,["a","a"]), [None,["a","a"]])
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 fixture	Actual	Expected	Outcome
multipart-no-top-content-range fixture 0	`[None, ['a1', 'b']]`	`[None, ['a1', 'b']]`	Passed
multipart-no-top-content-range fixture 1	`[None, ['a1']]`	`['a1', []]`	Failed
multipart-no-top-content-range fixture 2	`[None, []]`	`[None, []]`	Passed
multipart-no-top-content-range fixture 3	`[None, ['a', 'b', 'c']]`	`[None, ['a', 'b', 'c']]`	Passed
multipart-no-top-content-range fixture 4	`[None, ['']]`	`['', []]`	Failed
multipart-no-top-content-range fixture 5	`[None, ['a', 'a']]`	`[None, ['a', 'a']]`	Passed

SHA-256 / 7d698ad113d80922fd00c4844595e3a0cb1318990aa29dc45b8baea14158493f

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(parts, individual):
    return [individual[0],[]] if parts==1 else [None,individual]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multipart-no-top-content-range fixture 0', solve(2,["a"+str(N),"b"]), [None,["a"+str(N),"b"]])
check('multipart-no-top-content-range fixture 1', solve(1,["a"+str(N)]), ["a"+str(N),[]])
check('multipart-no-top-content-range fixture 2', solve(0,[]), [None,[]])
check('multipart-no-top-content-range fixture 3', solve(3,["a","b","c"]), [None,["a","b","c"]])
check('multipart-no-top-content-range fixture 4', solve(1,[""]), ["",[]])
check('multipart-no-top-content-range fixture 5', solve(2,["a","a"]), [None,["a","a"]])
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 fixture	Actual	Expected	Outcome
multipart-no-top-content-range fixture 0	`[None, ['a1', 'b']]`	`[None, ['a1', 'b']]`	Passed
multipart-no-top-content-range fixture 1	`['a1', []]`	`['a1', []]`	Passed
multipart-no-top-content-range fixture 2	`[None, []]`	`[None, []]`	Passed
multipart-no-top-content-range fixture 3	`[None, ['a', 'b', 'c']]`	`[None, ['a', 'b', 'c']]`	Passed
multipart-no-top-content-range fixture 4	`['', []]`	`['', []]`	Passed
multipart-no-top-content-range fixture 5	`[None, ['a', 'a']]`	`[None, ['a', 'a']]`	Passed

SHA-256 / 6aff7e851d5fec2567f02a212e09c060959f59740678b0fe717f5238792fce65

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 2026-09-29T14:41:16.292990+00:00.

Case digest / a0ab7147c0923e4655e786ba26b7f495c1791043ceafe0e25e6895e2766d38d4