FA-6931 / Content negotiation / Open access
Accept quality product combines independent dimensions · case 01
Accept quality product combines independent dimensions.
ROOT CAUSE
The faulty implementation uses `max(media,encoding,language)` for the accept-quality-product-combines-independent-dimensions decision.
VERIFIED REPAIR
Apply the explicit accept-quality-product-combines-independent-dimensions contract, including the tested boundary and negative cases.
Unsuccessful approach: The attempted repair uses `(media+encoding+language)/3` and still violates a separate fixture.
Case contract
Bounded offline decision model: accept quality product combines independent dimensions. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.
Why this case matters
This deterministic content negotiation model isolates the accept-quality-product-combines-independent-dimensions 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(media, encoding, language):
return max(media,encoding,language)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(1, 0, 1), 0)", "check('fixture 2', solve(0.5, 0.5, 0.5), 0.125)", "check('fixture 3', solve(1, 1, 1), 1)", "check('fixture 4', solve(0, 0, 0), 0)"]
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 | 0.5 | 0.125 | Failed |
| fixture 3 | 1 | 1 | Passed |
| fixture 4 | 0 | 0 | Passed |
| fixture 1 | 1 | 0 | Failed |
SHA-256 / 9da208f9d3f7e67fef9ee6882d122a7d19d5427496b1007152ba105c5fef52b2
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(media, encoding, language):
return (media+encoding+language)/3
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(1, 0, 1), 0)", "check('fixture 2', solve(0.5, 0.5, 0.5), 0.125)", "check('fixture 3', solve(1, 1, 1), 1)", "check('fixture 4', solve(0, 0, 0), 0)"]
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 | 0.5 | 0.125 | Failed |
| fixture 3 | 1.0 | 1 | Passed |
| fixture 4 | 0.0 | 0 | Passed |
| fixture 1 | 0.6666666666666666 | 0 | Failed |
SHA-256 / fa47c7ae8d8ea816cc5f2743eb1c9314d1c2740711e3a1d7d771c9fb8b5ded02
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(media, encoding, language):
return media*encoding*language
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(1, 0, 1), 0)", "check('fixture 2', solve(0.5, 0.5, 0.5), 0.125)", "check('fixture 3', solve(1, 1, 1), 1)", "check('fixture 4', solve(0, 0, 0), 0)"]
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 | 0.125 | 0.125 | Passed |
| fixture 3 | 1 | 1 | Passed |
| fixture 4 | 0 | 0 | Passed |
| fixture 1 | 0 | 0 | Passed |
SHA-256 / 985f964a36fe5adf3ac161058a7e47a22d7ac1b6324cc80e8bcd205fca1f70ec
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 2026-09-29T14:38:06.737800+00:00.
Case digest / 2b658342c1480bd761ada2631717d9711909aecb1356f1519d2e4e602335f2c7