FA-26356 / HTTP ranges / Open access

An If-None-Match list compares complete opaque values · case 01

An If-None-Match list compares complete opaque values.

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

ROOT CAUSE

The etag-list-not-substring decision uses return [304, ""] if any(t in current for t in requested) else [206,body].

VERIFIED REPAIR

Apply the bounded decision exactly: return [304, ""] if current in requested else [206,body]

Unsuccessful approach: The partial repair uses return [304, ""] if requested and requested[0] == current else [206,body], which still violates the stated contract.

Case contract

Inputs are parsed weak-normalized opaque tag strings. Return 304 if current is a complete member; otherwise return [206,body].

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(requested, current, body):
    return [304, ""] if any(t in current for t in requested) else [206,body]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('etag-list-not-substring fixture 0', solve( ["v"],"v"+str(N),"p"*N), [206,"p"*N])
check('etag-list-not-substring fixture 1', solve(["old","v"+str(N)],"v"+str(N),"p"), [304,""])
check('etag-list-not-substring fixture 2', solve([],"v","p"*N), [206,"p"*N])
check('etag-list-not-substring fixture 3', solve(["v"],"v","p"), [304,""])
check('etag-list-not-substring fixture 4', solve([""],"v","p"), [206,"p"])
check('etag-list-not-substring fixture 5', solve(["a","b"],"c","p"), [206,"p"])
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
etag-list-not-substring fixture 0	`[304, '']`	`[206, 'p']`	Failed
etag-list-not-substring fixture 1	`[304, '']`	`[304, '']`	Passed
etag-list-not-substring fixture 2	`[206, 'p']`	`[206, 'p']`	Passed
etag-list-not-substring fixture 3	`[304, '']`	`[304, '']`	Passed
etag-list-not-substring fixture 4	`[304, '']`	`[206, 'p']`	Failed
etag-list-not-substring fixture 5	`[206, 'p']`	`[206, 'p']`	Passed

SHA-256 / 995c213034d48a01004933c95f585c5f71563f796d66cb618e04392a04d19266

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(requested, current, body):
    return [304, ""] if requested and requested[0] == current else [206,body]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('etag-list-not-substring fixture 0', solve( ["v"],"v"+str(N),"p"*N), [206,"p"*N])
check('etag-list-not-substring fixture 1', solve(["old","v"+str(N)],"v"+str(N),"p"), [304,""])
check('etag-list-not-substring fixture 2', solve([],"v","p"*N), [206,"p"*N])
check('etag-list-not-substring fixture 3', solve(["v"],"v","p"), [304,""])
check('etag-list-not-substring fixture 4', solve([""],"v","p"), [206,"p"])
check('etag-list-not-substring fixture 5', solve(["a","b"],"c","p"), [206,"p"])
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
etag-list-not-substring fixture 0	`[206, 'p']`	`[206, 'p']`	Passed
etag-list-not-substring fixture 1	`[206, 'p']`	`[304, '']`	Failed
etag-list-not-substring fixture 2	`[206, 'p']`	`[206, 'p']`	Passed
etag-list-not-substring fixture 3	`[304, '']`	`[304, '']`	Passed
etag-list-not-substring fixture 4	`[206, 'p']`	`[206, 'p']`	Passed
etag-list-not-substring fixture 5	`[206, 'p']`	`[206, 'p']`	Passed

SHA-256 / b91e905dc28a3d680e33174e0b229e6e22d3a2a35b434010e5c6b0f1a08703d6

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(requested, current, body):
    return [304, ""] if current in requested else [206,body]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('etag-list-not-substring fixture 0', solve( ["v"],"v"+str(N),"p"*N), [206,"p"*N])
check('etag-list-not-substring fixture 1', solve(["old","v"+str(N)],"v"+str(N),"p"), [304,""])
check('etag-list-not-substring fixture 2', solve([],"v","p"*N), [206,"p"*N])
check('etag-list-not-substring fixture 3', solve(["v"],"v","p"), [304,""])
check('etag-list-not-substring fixture 4', solve([""],"v","p"), [206,"p"])
check('etag-list-not-substring fixture 5', solve(["a","b"],"c","p"), [206,"p"])
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
etag-list-not-substring fixture 0	`[206, 'p']`	`[206, 'p']`	Passed
etag-list-not-substring fixture 1	`[304, '']`	`[304, '']`	Passed
etag-list-not-substring fixture 2	`[206, 'p']`	`[206, 'p']`	Passed
etag-list-not-substring fixture 3	`[304, '']`	`[304, '']`	Passed
etag-list-not-substring fixture 4	`[206, 'p']`	`[206, 'p']`	Passed
etag-list-not-substring fixture 5	`[206, 'p']`	`[206, 'p']`	Passed

SHA-256 / dd0dc95c691529b8080801a9df10db8664dc0bc65857f2b7ad4c337febee11a4

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 2026-09-29T14:41:15.219976+00:00.

Case digest / ff4c43537dda875ea35a102e096da7451596704e42e3d83f10813bac9bcb5fba