FA-26686 / HTTP ranges / Open access

Range header budgets include commas and unit prefix bytes · case 01

Range header budgets include commas and unit prefix bytes.

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

ROOT CAUSE

The range-header-complete-budget decision uses return sum(map(len,members))<=limit.

VERIFIED REPAIR

Apply the bounded decision exactly: return len(unit)+1+len(",".join(members))<=limit

Unsuccessful approach: The partial repair uses return len(",".join(members))<=limit, which still violates the stated contract.

Case contract

ASCII wire field is unit=comma-joined-members. Return within iff total field byte length<=limit.

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(unit, members, limit):
    return sum(map(len,members))<=limit
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('range-header-complete-budget fixture 0', solve("bytes",["0-"+str(N)],3), False)
check('range-header-complete-budget fixture 1', solve("bytes",["0-1","2-3"],10), False)
check('range-header-complete-budget fixture 2', solve("bytes",["0-1"],9), True)
check('range-header-complete-budget fixture 3', solve("bytes",[],6), True)
check('range-header-complete-budget fixture 4', solve("bytes",[],5), False)
check('range-header-complete-budget fixture 5', solve("x",["a"],3), True)
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
range-header-complete-budget fixture 0	`True`	`False`	Failed
range-header-complete-budget fixture 1	`True`	`False`	Failed
range-header-complete-budget fixture 2	`True`	`True`	Passed
range-header-complete-budget fixture 3	`True`	`True`	Passed
range-header-complete-budget fixture 4	`True`	`False`	Failed
range-header-complete-budget fixture 5	`True`	`True`	Passed

SHA-256 / dffc46d76f3d1d0e9d66f5e2d076facfda56590417776fb71722f590e6c3c6aa

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(unit, members, limit):
    return len(",".join(members))<=limit
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('range-header-complete-budget fixture 0', solve("bytes",["0-"+str(N)],3), False)
check('range-header-complete-budget fixture 1', solve("bytes",["0-1","2-3"],10), False)
check('range-header-complete-budget fixture 2', solve("bytes",["0-1"],9), True)
check('range-header-complete-budget fixture 3', solve("bytes",[],6), True)
check('range-header-complete-budget fixture 4', solve("bytes",[],5), False)
check('range-header-complete-budget fixture 5', solve("x",["a"],3), True)
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
range-header-complete-budget fixture 0	`True`	`False`	Failed
range-header-complete-budget fixture 1	`True`	`False`	Failed
range-header-complete-budget fixture 2	`True`	`True`	Passed
range-header-complete-budget fixture 3	`True`	`True`	Passed
range-header-complete-budget fixture 4	`True`	`False`	Failed
range-header-complete-budget fixture 5	`True`	`True`	Passed

SHA-256 / d9c054701e10e99239d56af0a9f4fb271c00c41e2fb3837bdfd6fcb8b431de98

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(unit, members, limit):
    return len(unit)+1+len(",".join(members))<=limit
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('range-header-complete-budget fixture 0', solve("bytes",["0-"+str(N)],3), False)
check('range-header-complete-budget fixture 1', solve("bytes",["0-1","2-3"],10), False)
check('range-header-complete-budget fixture 2', solve("bytes",["0-1"],9), True)
check('range-header-complete-budget fixture 3', solve("bytes",[],6), True)
check('range-header-complete-budget fixture 4', solve("bytes",[],5), False)
check('range-header-complete-budget fixture 5', solve("x",["a"],3), True)
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
range-header-complete-budget fixture 0	`False`	`False`	Passed
range-header-complete-budget fixture 1	`False`	`False`	Passed
range-header-complete-budget fixture 2	`True`	`True`	Passed
range-header-complete-budget fixture 3	`True`	`True`	Passed
range-header-complete-budget fixture 4	`False`	`False`	Passed
range-header-complete-budget fixture 5	`True`	`True`	Passed

SHA-256 / 92505c8bf99c30ed150086209b8540607c5a16d267972df6f0d2ebdf3560257b

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 2026-09-29T14:41:18.188915+00:00.

Case digest / c59345c2b8d2cc7e81d29cee8db83496c01fd1315f4a008fb1d75da965137ae1