FA-7496 / Multiplexed protocols / Open access

Http2 settings ack must have empty payload · case 01

Http2 settings ack must have empty payload.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The faulty implementation uses `payload_size == 0` for the http2-settings-ack-must-have-empty-payload decision.

VERIFIED REPAIR

Apply the explicit http2-settings-ack-must-have-empty-payload contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `not ack or payload_size % 6 == 0` and still violates a separate fixture.

Case contract

Bounded offline decision model: http2 settings ack must have empty payload. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.

Why this case matters

This deterministic multiplexed protocols model isolates the http2-settings-ack-must-have-empty-payload policy at a network component boundary.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(ack, payload_size):
    return payload_size == 0
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 6), False)", "check('fixture 2', solve(False, 6), True)", "check('fixture 3', solve(True, 0), True)", "check('fixture 4', solve(False, 0), True)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
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
fixture 2	`False`	`True`	Failed
fixture 3	`True`	`True`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`False`	`False`	Passed

SHA-256 / 4a1ae3c79108979e6d4318efcc662457116c5f5364872628988f8946fdc01c5a

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(ack, payload_size):
    return not ack or payload_size % 6 == 0
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 6), False)", "check('fixture 2', solve(False, 6), True)", "check('fixture 3', solve(True, 0), True)", "check('fixture 4', solve(False, 0), True)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
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
fixture 2	`True`	`True`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`True`	`False`	Failed

SHA-256 / cd5fdf9e591b4a016b428313ffe986a98f0725f24b1600a8f4a6d8ca681b0875

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(ack, payload_size):
    return not ack or payload_size == 0
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 6), False)", "check('fixture 2', solve(False, 6), True)", "check('fixture 3', solve(True, 0), True)", "check('fixture 4', solve(False, 0), True)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
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
fixture 2	`True`	`True`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`False`	`False`	Passed

SHA-256 / 7a8e784846e23c704eac579c858c847d9e3c3dd6f8fc90b861b85d6e21de44ad

Verification & scope

Bounded deterministic policy model over validated inputs; not a complete protocol stack or an interoperability claim. The five variants rotate the same explicit fixture set. 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 2026-09-29T14:38:12.636343+00:00.

Case digest / b3cb1664b23045756b99e67ff324f29cb6e32745c61de05a8e571ae9570b859b