FA-26721 / HTTP ranges / Open access

Conflicting duplicate Content-Range fields cannot choose an arbitrary winner · case 01

Conflicting duplicate Content-Range fields cannot choose an arbitrary winner.

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

ROOT CAUSE

The content-range-duplicate-disagreement decision uses return values[0] if values else None.

THE FAILURE

The content-range-duplicate-disagreement decision uses return values[0] if values else None.

Unsuccessful approach: The partial repair uses return values[-1] if values else None, which still violates the stated contract.

Case contract

Parsed field values are normalized strings. Return sole agreed value if nonempty and all identical, else None.

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(values):
    return values[0] if values else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('content-range-duplicate-disagreement fixture 0', solve( ["r"+str(N),"other"]), None)
check('content-range-duplicate-disagreement fixture 1', solve(["r","r"]), "r")
check('content-range-duplicate-disagreement fixture 2', solve([]), None)
check('content-range-duplicate-disagreement fixture 3', solve(["r"]), "r")
check('content-range-duplicate-disagreement fixture 4', solve(["a","b","a"]), None)
check('content-range-duplicate-disagreement fixture 5', solve(["",""]), "")
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
content-range-duplicate-disagreement fixture 0	`r1`	`None`	Failed
content-range-duplicate-disagreement fixture 1	`r`	`r`	Passed
content-range-duplicate-disagreement fixture 2	`None`	`None`	Passed
content-range-duplicate-disagreement fixture 3	`r`	`r`	Passed
content-range-duplicate-disagreement fixture 4	`a`	`None`	Failed
content-range-duplicate-disagreement fixture 5			Passed

SHA-256 / 173891241e114507d23367f6ef45b9755107d016eebee017ff546337a159e3f6

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(values):
    return values[-1] if values else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('content-range-duplicate-disagreement fixture 0', solve( ["r"+str(N),"other"]), None)
check('content-range-duplicate-disagreement fixture 1', solve(["r","r"]), "r")
check('content-range-duplicate-disagreement fixture 2', solve([]), None)
check('content-range-duplicate-disagreement fixture 3', solve(["r"]), "r")
check('content-range-duplicate-disagreement fixture 4', solve(["a","b","a"]), None)
check('content-range-duplicate-disagreement fixture 5', solve(["",""]), "")
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
content-range-duplicate-disagreement fixture 0	`other`	`None`	Failed
content-range-duplicate-disagreement fixture 1	`r`	`r`	Passed
content-range-duplicate-disagreement fixture 2	`None`	`None`	Passed
content-range-duplicate-disagreement fixture 3	`r`	`r`	Passed
content-range-duplicate-disagreement fixture 4	`a`	`None`	Failed
content-range-duplicate-disagreement fixture 5			Passed

SHA-256 / 3e1bc4ea5417a8da2b9903f3ba879eb04508b48ea7ef2945f3f3b7aac3fe7e1b

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 6 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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 2026-09-29T14:41:18.566114+00:00.

Case digest / 1c53e870f926bb7424c63f4ca9ca8e3cc73046a2421c1543c4898de2c388421f