FA-26816 / HTTP ranges / Open access

Each received part needs its own explicit range metadata · case 01

Each received part needs its own explicit range metadata.

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

ROOT CAUSE

The multipart-client-missing-range decision uses return [b for r,b in parts].

THE FAILURE

The multipart-client-missing-range decision uses return [b for r,b in parts].

Unsuccessful approach: The partial repair uses return [b for r,b in parts] if not parts or parts[0][0] is not None else None, which still violates the stated contract.

Case contract

parts are [content-range-or-null,body]. Return bodies only when every part has range metadata; never inherit a preceding range.

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):
    return [b for r,b in parts]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multipart-client-missing-range fixture 0', solve([["r","a"*N],[None,"b"]]), None)
check('multipart-client-missing-range fixture 1', solve([[None,"a"]]), None)
check('multipart-client-missing-range fixture 2', solve([["r","a"*N]]), ["a"*N])
check('multipart-client-missing-range fixture 3', solve([]), [])
check('multipart-client-missing-range fixture 4', solve([["r",""],["s","b"]]), ["","b"])
check('multipart-client-missing-range fixture 5', solve([["r","a"],["s","b"]]), ["a","b"])
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-client-missing-range fixture 0	`['a', 'b']`	`None`	Failed
multipart-client-missing-range fixture 1	`['a']`	`None`	Failed
multipart-client-missing-range fixture 2	`['a']`	`['a']`	Passed
multipart-client-missing-range fixture 3	`[]`	`[]`	Passed
multipart-client-missing-range fixture 4	`['', 'b']`	`['', 'b']`	Passed
multipart-client-missing-range fixture 5	`['a', 'b']`	`['a', 'b']`	Passed

SHA-256 / 4521e8f1e5db9b27f2cecf211d60bba28644abfdf1564ebefa1deeffe57a0fc8

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(parts):
    return [b for r,b in parts] if not parts or parts[0][0] is not None else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multipart-client-missing-range fixture 0', solve([["r","a"*N],[None,"b"]]), None)
check('multipart-client-missing-range fixture 1', solve([[None,"a"]]), None)
check('multipart-client-missing-range fixture 2', solve([["r","a"*N]]), ["a"*N])
check('multipart-client-missing-range fixture 3', solve([]), [])
check('multipart-client-missing-range fixture 4', solve([["r",""],["s","b"]]), ["","b"])
check('multipart-client-missing-range fixture 5', solve([["r","a"],["s","b"]]), ["a","b"])
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-client-missing-range fixture 0	`['a', 'b']`	`None`	Failed
multipart-client-missing-range fixture 1	`None`	`None`	Passed
multipart-client-missing-range fixture 2	`['a']`	`['a']`	Passed
multipart-client-missing-range fixture 3	`[]`	`[]`	Passed
multipart-client-missing-range fixture 4	`['', 'b']`	`['', 'b']`	Passed
multipart-client-missing-range fixture 5	`['a', 'b']`	`['a', 'b']`	Passed

SHA-256 / 15ae60e81408b9623e34a031b9f43722ce703f2e028899385717cfb3c681c0d5

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 2026-09-29T14:41:19.383894+00:00.

Case digest / b51405cb4f67f4499cbdd5448bd1c08be028d8e8342231b24484b1943ee42d83