FA-26826 / HTTP ranges / Open access

Bytes after the closing delimiter do not enter the last range body · case 01

Bytes after the closing delimiter do not enter the last range body.

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

ROOT CAUSE

The multipart-client-epilogue-not-payload decision uses return payload+epilogue.

VERIFIED REPAIR

Apply the bounded decision exactly: return payload if closed else payload+epilogue

Unsuccessful approach: The partial repair uses return payload, which still violates the stated contract.

Case contract

Return payload unchanged after close; before close, received bytes extend the still-open payload.

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(payload, epilogue, closed):
    return payload+epilogue
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multipart-client-epilogue-not-payload fixture 0', solve("p"*N,"epilogue",True), "p"*N)
check('multipart-client-epilogue-not-payload fixture 1', solve("p","q",False), "pq")
check('multipart-client-epilogue-not-payload fixture 2', solve("","e",True), "")
check('multipart-client-epilogue-not-payload fixture 3', solve("p","",True), "p")
check('multipart-client-epilogue-not-payload fixture 4', solve("","x",False), "x")
check('multipart-client-epilogue-not-payload fixture 5', solve("","",False), "")
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-epilogue-not-payload fixture 0	`pepilogue`	`p`	Failed
multipart-client-epilogue-not-payload fixture 1	`pq`	`pq`	Passed
multipart-client-epilogue-not-payload fixture 2	`e`		Failed
multipart-client-epilogue-not-payload fixture 3	`p`	`p`	Passed
multipart-client-epilogue-not-payload fixture 4	`x`	`x`	Passed
multipart-client-epilogue-not-payload fixture 5			Passed

SHA-256 / 9106f443b2ca7bc7892b00af50256120e95f90291a83e606695ab491ea29ac87

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(payload, epilogue, closed):
    return payload
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multipart-client-epilogue-not-payload fixture 0', solve("p"*N,"epilogue",True), "p"*N)
check('multipart-client-epilogue-not-payload fixture 1', solve("p","q",False), "pq")
check('multipart-client-epilogue-not-payload fixture 2', solve("","e",True), "")
check('multipart-client-epilogue-not-payload fixture 3', solve("p","",True), "p")
check('multipart-client-epilogue-not-payload fixture 4', solve("","x",False), "x")
check('multipart-client-epilogue-not-payload fixture 5', solve("","",False), "")
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-epilogue-not-payload fixture 0	`p`	`p`	Passed
multipart-client-epilogue-not-payload fixture 1	`p`	`pq`	Failed
multipart-client-epilogue-not-payload fixture 2			Passed
multipart-client-epilogue-not-payload fixture 3	`p`	`p`	Passed
multipart-client-epilogue-not-payload fixture 4		`x`	Failed
multipart-client-epilogue-not-payload fixture 5			Passed

SHA-256 / d3e7658b8a98cbacc0d147ad07b94169d98f925b56437db15205e2d169eccc2c

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(payload, epilogue, closed):
    return payload if closed else payload+epilogue
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multipart-client-epilogue-not-payload fixture 0', solve("p"*N,"epilogue",True), "p"*N)
check('multipart-client-epilogue-not-payload fixture 1', solve("p","q",False), "pq")
check('multipart-client-epilogue-not-payload fixture 2', solve("","e",True), "")
check('multipart-client-epilogue-not-payload fixture 3', solve("p","",True), "p")
check('multipart-client-epilogue-not-payload fixture 4', solve("","x",False), "x")
check('multipart-client-epilogue-not-payload fixture 5', solve("","",False), "")
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-epilogue-not-payload fixture 0	`p`	`p`	Passed
multipart-client-epilogue-not-payload fixture 1	`pq`	`pq`	Passed
multipart-client-epilogue-not-payload fixture 2			Passed
multipart-client-epilogue-not-payload fixture 3	`p`	`p`	Passed
multipart-client-epilogue-not-payload fixture 4	`x`	`x`	Passed
multipart-client-epilogue-not-payload fixture 5			Passed

SHA-256 / 39e3561c7650c4b6a2c6c2451a3470983e4b8a966024460778761aaf3e877af2

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 2026-09-29T14:41:19.404586+00:00.

Case digest / c6469b40280c27fbe74e15b078010c93af414c373dee828102ae70d28876925b