FA-26726 / HTTP ranges / Open access

A byte-range client rejects partial metadata in a different unit · case 01

A byte-range client rejects partial metadata in a different unit.

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

ROOT CAUSE

The content-range-unit-mismatch decision uses return body.

VERIFIED REPAIR

Apply the bounded decision exactly: return body if actual_unit==expected_unit else None

Unsuccessful approach: The partial repair uses return body if actual_unit.startswith(expected_unit) else None, which still violates the stated contract.

Case contract

Parsed units are case-normalized tokens. Accept payload only when units match exactly; otherwise 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(expected_unit, actual_unit, body):
    return body
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('content-range-unit-mismatch fixture 0', solve("bytes","bytesx","p"*N), None)
check('content-range-unit-mismatch fixture 1', solve("bytes","items","p"), None)
check('content-range-unit-mismatch fixture 2', solve("bytes","bytes","p"*N), "p"*N)
check('content-range-unit-mismatch fixture 3', solve("items","items","p"), "p")
check('content-range-unit-mismatch fixture 4', solve("bytes","","p"), None)
check('content-range-unit-mismatch fixture 5', solve("bytes","bytes",""), "")
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-unit-mismatch fixture 0	`p`	`None`	Failed
content-range-unit-mismatch fixture 1	`p`	`None`	Failed
content-range-unit-mismatch fixture 2	`p`	`p`	Passed
content-range-unit-mismatch fixture 3	`p`	`p`	Passed
content-range-unit-mismatch fixture 4	`p`	`None`	Failed
content-range-unit-mismatch fixture 5			Passed

SHA-256 / b44b18e972c2d2d3f9dfd199add00ba81369bfb173259d8075b516ef228854cf

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(expected_unit, actual_unit, body):
    return body if actual_unit.startswith(expected_unit) else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('content-range-unit-mismatch fixture 0', solve("bytes","bytesx","p"*N), None)
check('content-range-unit-mismatch fixture 1', solve("bytes","items","p"), None)
check('content-range-unit-mismatch fixture 2', solve("bytes","bytes","p"*N), "p"*N)
check('content-range-unit-mismatch fixture 3', solve("items","items","p"), "p")
check('content-range-unit-mismatch fixture 4', solve("bytes","","p"), None)
check('content-range-unit-mismatch fixture 5', solve("bytes","bytes",""), "")
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-unit-mismatch fixture 0	`p`	`None`	Failed
content-range-unit-mismatch fixture 1	`None`	`None`	Passed
content-range-unit-mismatch fixture 2	`p`	`p`	Passed
content-range-unit-mismatch fixture 3	`p`	`p`	Passed
content-range-unit-mismatch fixture 4	`None`	`None`	Passed
content-range-unit-mismatch fixture 5			Passed

SHA-256 / 477230bf3b06231b141d87a33b38b45f9c7485114c83a9ee22989037c856d87f

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(expected_unit, actual_unit, body):
    return body if actual_unit==expected_unit else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('content-range-unit-mismatch fixture 0', solve("bytes","bytesx","p"*N), None)
check('content-range-unit-mismatch fixture 1', solve("bytes","items","p"), None)
check('content-range-unit-mismatch fixture 2', solve("bytes","bytes","p"*N), "p"*N)
check('content-range-unit-mismatch fixture 3', solve("items","items","p"), "p")
check('content-range-unit-mismatch fixture 4', solve("bytes","","p"), None)
check('content-range-unit-mismatch fixture 5', solve("bytes","bytes",""), "")
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-unit-mismatch fixture 0	`None`	`None`	Passed
content-range-unit-mismatch fixture 1	`None`	`None`	Passed
content-range-unit-mismatch fixture 2	`p`	`p`	Passed
content-range-unit-mismatch fixture 3	`p`	`p`	Passed
content-range-unit-mismatch fixture 4	`None`	`None`	Passed
content-range-unit-mismatch fixture 5			Passed

SHA-256 / ac769f8eea840b0f9238b3b84bae2f1a06f5ac9ea8d15f04d8dcdde83c4f7d73

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 2026-09-29T14:41:18.610509+00:00.

Case digest / e13c0b8adfef26d0c0e355742dbf06166cb458c67603f884e9bbadc44d331c3b