FA-6941 / Content negotiation / Open access
Parameter specificity counts matched constraints · case 01
Parameter specificity counts matched constraints.
ROOT CAUSE
The faulty implementation uses `len(actual)` for the parameter-specificity-counts-matched-constraints decision.
VERIFIED REPAIR
Apply the explicit parameter-specificity-counts-matched-constraints contract, including the tested boundary and negative cases.
Unsuccessful approach: The attempted repair uses `len(required)` and still violates a separate fixture.
Case contract
Bounded offline decision model: parameter specificity counts matched constraints. 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 parameter-specificity-counts-matched-constraints 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(required, actual):
return len(actual)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve({'a': 1, 'b': 2}, {'a': 1, 'b': 3, 'c': 4}), 1)", "check('fixture 2', solve({}, {'x': 1}), 0)", "check('fixture 3', solve({'a': 1}, {'a': 1}), 1)", "check('fixture 4', solve({'a': 1}, {}), 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 | 1 | 0 | Failed |
| fixture 3 | 1 | 1 | Passed |
| fixture 4 | 0 | 0 | Passed |
| fixture 1 | 3 | 1 | Failed |
SHA-256 / 4fc5a657aae69ed703437d516e416d8bc8d38db2f8983f6869da2777262cd6ee
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(required, actual):
return len(required)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve({'a': 1, 'b': 2}, {'a': 1, 'b': 3, 'c': 4}), 1)", "check('fixture 2', solve({}, {'x': 1}), 0)", "check('fixture 3', solve({'a': 1}, {'a': 1}), 1)", "check('fixture 4', solve({'a': 1}, {}), 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 | 0 | Passed |
| fixture 3 | 1 | 1 | Passed |
| fixture 4 | 1 | 0 | Failed |
| fixture 1 | 2 | 1 | Failed |
SHA-256 / a01a628b60fdd6cce1e57d74c132d0b837cd36d491a457b53eb8eaf19c71a6a4
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(required, actual):
return sum(actual.get(k)==v for k,v in required.items())
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve({'a': 1, 'b': 2}, {'a': 1, 'b': 3, 'c': 4}), 1)", "check('fixture 2', solve({}, {'x': 1}), 0)", "check('fixture 3', solve({'a': 1}, {'a': 1}), 1)", "check('fixture 4', solve({'a': 1}, {}), 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 | 0 | Passed |
| fixture 3 | 1 | 1 | Passed |
| fixture 4 | 0 | 0 | Passed |
| fixture 1 | 1 | 1 | Passed |
SHA-256 / 6f2bb9badaec73ab23b09bf827acfe3d9e642ad8dbfcefb83be47384f10c7528
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 2026-09-29T14:38:06.798982+00:00.
Case digest / 64847fa3344142171d1776af86844c0b11beeb6f33fdbdb1cc1711862293b8bc