FA-7486 / Multiplexed protocols / Open access

Http2 window update rejects zero and overflow · case 01

Http2 window update rejects zero and overflow.

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

ROOT CAUSE

The faulty implementation uses `current+increment <= 2147483647` for the http2-window-update-rejects-zero-and-overflow decision.

VERIFIED REPAIR

Apply the explicit http2-window-update-rejects-zero-and-overflow contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `increment > 0` and still violates a separate fixture.

Case contract

Bounded offline decision model: http2 window update rejects zero and overflow. 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-window-update-rejects-zero-and-overflow 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(current, increment):
    return current+increment <= 2147483647
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 0), False)", "check('fixture 2', solve(2147483647, 1), False)", "check('fixture 3', solve(0, 1), True)", "check('fixture 4', solve(-10, 1), 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`	`False`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`True`	`False`	Failed

SHA-256 / 9291e15003671f8476d420d1f59b1be9c33417f6c5b0418eeee28348a48da13d

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(current, increment):
    return increment > 0
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 0), False)", "check('fixture 2', solve(2147483647, 1), False)", "check('fixture 3', solve(0, 1), True)", "check('fixture 4', solve(-10, 1), 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`	`False`	Failed
fixture 3	`True`	`True`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`False`	`False`	Passed

SHA-256 / b8246429a74789f9573806b30613594b158056a5ceaefad82d491f63a971bf32

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(current, increment):
    return 1 <= increment and current+increment <= 2147483647
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(10, 0), False)", "check('fixture 2', solve(2147483647, 1), False)", "check('fixture 3', solve(0, 1), True)", "check('fixture 4', solve(-10, 1), 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`	`False`	Passed
fixture 3	`True`	`True`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`False`	`False`	Passed

SHA-256 / 774755ab9053d9f3439595255e2800d115eb7212fdaa83e138a2d133c6df2950

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 2026-09-29T14:38:12.535067+00:00.

Case digest / 8d77f23d5f9d556473aa4fb0447b43ed5e9a0ef60a512f177621ec23b9fe5157