FA-6651 / HTTP redirects / Open access

A redirect budget charges redirects rather than the initial request · case 01

A redirect budget charges redirects rather than the initial request.

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

ROOT CAUSE

The faulty implementation uses `redirects <= limit` for the redirect-budget decision.

VERIFIED REPAIR

Apply the explicit redirect-budget contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `redirects + 1 < limit` and still violates a separate fixture.

Case contract

A redirect budget charges redirects rather than the initial request: return the result specified by the explicit input/output boundary fixtures.

Why this case matters

This deterministic http redirects model isolates the redirect-budget 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(redirects, limit):
    return redirects <= limit
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(2, 2), False)", "check('fixture 2', solve(1, 2), True)", "check('fixture 3', solve(0, 0), False)", "check('fixture 4', solve(0, 3), 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`	`False`	Failed
fixture 4	`True`	`True`	Passed
fixture 1	`True`	`False`	Failed

SHA-256 / af74133717f97b7521ae3e762529f9be208ce3fd93a1d62841fd77ed9addebe6

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

SHA-256 / 9b271e7d5dbb68c93c405792f17e6658a206f394d46bd6e705cb85188fd7cbbb

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(redirects, limit):
    return redirects < limit
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(2, 2), False)", "check('fixture 2', solve(1, 2), True)", "check('fixture 3', solve(0, 0), False)", "check('fixture 4', solve(0, 3), 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	`False`	`False`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`False`	`False`	Passed

SHA-256 / d7950513f7b2088cece039a923e47f4c7727bb2805d52fa7c1290c179fcdf2b3

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 2026-09-29T14:38:04.015784+00:00.

Case digest / 05bc00f8b6df94d87863cb533558757b35332eebda32ae73ef999343953a075f