FA-7826 / Connection lifecycle / Open access

Connection backpressure does not drop queued request order · case 01

Connection backpressure does not drop queued request order.

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

ROOT CAUSE

The faulty implementation uses `(queued[-1],queued[:-1]) if ready and queued else (None,queued)` for the connection-backpressure-does-not-drop-queued-request-order decision.

VERIFIED REPAIR

Apply the explicit connection-backpressure-does-not-drop-queued-request-order contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `(queued[0],queued[1:]) if queued else (None,queued)` and still violates a separate fixture.

Case contract

Bounded offline decision model: connection backpressure does not drop queued request order. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.

Why this case matters

This deterministic connection lifecycle model isolates the connection-backpressure-does-not-drop-queued-request-order 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(queued, ready):
    return (queued[-1],queued[:-1]) if ready and queued else (None,queued)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(['a', 'b'], True), ('a', ['b']))", "check('fixture 2', solve(['a'], False), (None, ['a']))", "check('fixture 3', solve([], True), (None, []))", "check('fixture 4', solve(['a'], True), ('a', []))"]
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	`[None, ['a']]`	`[None, ['a']]`	Passed
fixture 3	`[None, []]`	`[None, []]`	Passed
fixture 4	`['a', []]`	`['a', []]`	Passed
fixture 1	`['b', ['a']]`	`['a', ['b']]`	Failed

SHA-256 / f721c49c437689aa3fb46e48df4e3d51270154121e7cf8521949f85fbfcb6c4b

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(queued, ready):
    return (queued[0],queued[1:]) if queued else (None,queued)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(['a', 'b'], True), ('a', ['b']))", "check('fixture 2', solve(['a'], False), (None, ['a']))", "check('fixture 3', solve([], True), (None, []))", "check('fixture 4', solve(['a'], True), ('a', []))"]
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	`['a', []]`	`[None, ['a']]`	Failed
fixture 3	`[None, []]`	`[None, []]`	Passed
fixture 4	`['a', []]`	`['a', []]`	Passed
fixture 1	`['a', ['b']]`	`['a', ['b']]`	Passed

SHA-256 / 4c27a15175c3f4d054cab514454a47a528774b29fffe0dc1d6af095db46370c8

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(queued, ready):
    return (queued[0],queued[1:]) if ready and queued else (None,queued)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(['a', 'b'], True), ('a', ['b']))", "check('fixture 2', solve(['a'], False), (None, ['a']))", "check('fixture 3', solve([], True), (None, []))", "check('fixture 4', solve(['a'], True), ('a', []))"]
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	`[None, ['a']]`	`[None, ['a']]`	Passed
fixture 3	`[None, []]`	`[None, []]`	Passed
fixture 4	`['a', []]`	`['a', []]`	Passed
fixture 1	`['a', ['b']]`	`['a', ['b']]`	Passed

SHA-256 / 6ed9a9a5b01c5d900b6f6b4a7d1b0bd8b01e24bca4ba90f2addee21bd4349016

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 2026-09-29T14:38:15.574270+00:00.

Case digest / 3cf2295665a119ade116755bd72058bdd93694c6bf64c47e21ca6885eb26c126