FA-6676 / HTTP retries / Open access
Deterministic full jitter spans the entire capped delay interval · case 01
Deterministic full jitter spans the entire capped delay interval.
ROOT CAUSE
The faulty implementation uses `min(base * fraction, cap)` for the retry-jitter decision.
VERIFIED REPAIR
Apply the explicit retry-jitter contract, including the tested boundary and negative cases.
Unsuccessful approach: The attempted repair uses `min(base, cap) * (0.5 + fraction / 2)` and still violates a separate fixture.
Case contract
Deterministic full jitter spans the entire capped delay interval: return the result specified by the explicit input/output boundary fixtures.
Why this case matters
This deterministic http retries model isolates the retry-jitter 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(base, cap, fraction):
return min(base * fraction, cap)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(20, 10, 0.5), 5.0)", "check('fixture 2', solve(8, 10, 0), 0)", "check('fixture 3', solve(8, 10, 1), 8)", "check('fixture 4', solve(20, 10, 1), 10)"]
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 | 8 | 8 | Passed |
| fixture 4 | 10 | 10 | Passed |
| fixture 1 | 10.0 | 5.0 | Failed |
SHA-256 / a0b80e577a1d868fb34daa1524508703f0668dc86d001abdc86d2578c45418f8
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(base, cap, fraction):
return min(base, cap) * (0.5 + fraction / 2)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(20, 10, 0.5), 5.0)", "check('fixture 2', solve(8, 10, 0), 0)", "check('fixture 3', solve(8, 10, 1), 8)", "check('fixture 4', solve(20, 10, 1), 10)"]
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 | 4.0 | 0 | Failed |
| fixture 3 | 8.0 | 8 | Passed |
| fixture 4 | 10.0 | 10 | Passed |
| fixture 1 | 7.5 | 5.0 | Failed |
SHA-256 / 0918d922ed1016fb207c72a3162b5e3673f67fedce7c754a601c38610690a0c6
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(base, cap, fraction):
return min(base, cap) * fraction
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(20, 10, 0.5), 5.0)", "check('fixture 2', solve(8, 10, 0), 0)", "check('fixture 3', solve(8, 10, 1), 8)", "check('fixture 4', solve(20, 10, 1), 10)"]
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 | 8 | 8 | Passed |
| fixture 4 | 10 | 10 | Passed |
| fixture 1 | 5.0 | 5.0 | Passed |
SHA-256 / fa949b6f18cf1fc5850dd36d170524ae3815d83a35ff71feb7ff5673cfd2cc4a
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 2026-09-29T14:38:04.289129+00:00.
Case digest / 53507880aca7279c8be995c072953d74decaa44bc628a8b886b195ba4cbb3665