FA-6921 / Content negotiation / Open access
Range on encoded response addresses coded representation · case 01
Range on encoded response addresses coded representation.
ROOT CAUSE
The faulty implementation uses `plain[start:end+1]` for the range-on-encoded-response-addresses-coded-representation decision.
VERIFIED REPAIR
Apply the explicit range-on-encoded-response-addresses-coded-representation contract, including the tested boundary and negative cases.
Unsuccessful approach: The attempted repair uses `(coded if encoded else plain)[start:end]` and still violates a separate fixture.
Case contract
Given encoded, coded, plain, start, end, range on encoded response addresses coded representation. Return the protocol decision or transformed value; fields are validated and fixtures state boundary outcomes.
Why this case matters
This deterministic content negotiation model isolates the range-on-encoded-response-addresses-coded-representation 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(encoded, coded, plain, start, end):
return plain[start:end+1]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 'abcd', '0123456789', 1, 2), 'bc')", "check('fixture 2', solve(False, 'abcd', '0123456789', 1, 2), '12')", "check('fixture 3', solve(True, 'abc', 'x', 0, 0), 'a')", "check('fixture 4', solve(False, 'a', 'xyz', 1, 9), 'yz')"]
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 | 12 | 12 | Passed |
| fixture 3 | x | a | Failed |
| fixture 4 | yz | yz | Passed |
| fixture 1 | 12 | bc | Failed |
SHA-256 / 1352aeb370c09957f674594b7a282662efa1c69004e58ccc4aec5b53583bd3e2
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(encoded, coded, plain, start, end):
return (coded if encoded else plain)[start:end]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 'abcd', '0123456789', 1, 2), 'bc')", "check('fixture 2', solve(False, 'abcd', '0123456789', 1, 2), '12')", "check('fixture 3', solve(True, 'abc', 'x', 0, 0), 'a')", "check('fixture 4', solve(False, 'a', 'xyz', 1, 9), 'yz')"]
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 | 12 | Failed |
| fixture 3 | | a | Failed |
| fixture 4 | yz | yz | Passed |
| fixture 1 | b | bc | Failed |
SHA-256 / 5f0a417ebb262a65357d3ffb62c2c626e5e1937b5a93f826cb60fcfe83aecef8
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(encoded, coded, plain, start, end):
return (coded if encoded else plain)[start:end+1]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 'abcd', '0123456789', 1, 2), 'bc')", "check('fixture 2', solve(False, 'abcd', '0123456789', 1, 2), '12')", "check('fixture 3', solve(True, 'abc', 'x', 0, 0), 'a')", "check('fixture 4', solve(False, 'a', 'xyz', 1, 9), 'yz')"]
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 | 12 | 12 | Passed |
| fixture 3 | a | a | Passed |
| fixture 4 | yz | yz | Passed |
| fixture 1 | bc | bc | Passed |
SHA-256 / 849e54e063319b1484b31fb069cfd04bfe43000e6f505f38ded4aa93a022f800
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 2026-09-29T14:38:06.516116+00:00.
Case digest / cc1f7de087ee0b1b2cc5711d6263203499f6b62cd844de15c12974a6d403d358