FA-7181 / Network routing / Open access

Ipv4 and ipv6 endpoint identities remain distinct · case 01

Ipv4 and ipv6 endpoint identities remain distinct.

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

ROOT CAUSE

The faulty implementation uses `a.split(":")[-1] == b.split(":")[-1]` for the ipv4-and-ipv6-endpoint-identities-remain-distinct decision.

VERIFIED REPAIR

Apply the explicit ipv4-and-ipv6-endpoint-identities-remain-distinct contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `a == b` and still violates a separate fixture.

Case contract

Bounded offline decision model: ipv4 and ipv6 endpoint identities remain distinct. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.

Why this case matters

This deterministic network routing model isolates the ipv4-and-ipv6-endpoint-identities-remain-distinct 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(a, b):
    return a.split(":")[-1] == b.split(":")[-1]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('2001:db8::1', '2001:db8:0:0:0:0:0:1'), True)", "check('fixture 2', solve('::ffff:192.0.2.1', '192.0.2.1'), False)", "check('fixture 3', solve('::1', '::1'), True)", "check('fixture 4', solve('192.0.2.1', '192.0.2.2'), False)"]
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	`False`	`False`	Passed
fixture 1	`True`	`True`	Passed

SHA-256 / a6db31b3b08150876fc3dee6ad8b60ed63a80d14d06259f31adc4b467a38bb72

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(a, b):
    return a == b
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('2001:db8::1', '2001:db8:0:0:0:0:0:1'), True)", "check('fixture 2', solve('::ffff:192.0.2.1', '192.0.2.1'), False)", "check('fixture 3', solve('::1', '::1'), True)", "check('fixture 4', solve('192.0.2.1', '192.0.2.2'), False)"]
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	`False`	`False`	Passed
fixture 1	`False`	`True`	Failed

SHA-256 / a54b75c950ab2797d7e20ff6f3a16613a783f5f420325ecc13e542a61413d331

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(a, b):
    return ipaddress.ip_address(a) == ipaddress.ip_address(b)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve('2001:db8::1', '2001:db8:0:0:0:0:0:1'), True)", "check('fixture 2', solve('::ffff:192.0.2.1', '192.0.2.1'), False)", "check('fixture 3', solve('::1', '::1'), True)", "check('fixture 4', solve('192.0.2.1', '192.0.2.2'), False)"]
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	`False`	`False`	Passed
fixture 1	`True`	`True`	Passed

SHA-256 / cf813eee0c9087b36292d2e804bbc2e0bf99f0a1e358eb7bf04eae5a8dc8f9a2

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 2026-09-29T14:38:09.132953+00:00.

Case digest / fce211de78158ad6c0756ce19e1bd5f725b5d84328d10285cef29a3faf1fb49b