FAILURE MAP
← Case archive

FA-28141 / HTTP redirects / Open access

Release an intermediate response before following its target: drain required · case 01

Release an intermediate response before following its target: the drain required branch emits an incorrect decision.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The drain-required decision uses 'not drained'; this violates the stipulated controller policy.

THE FAILURE

The drain-required decision uses 'not drained'; this violates the stipulated controller policy.

Unsuccessful approach: The partial repair uses 'remaining >= 0' and still fails an explicit boundary or control.

Case contract

Release an intermediate response before following its target. The explicit fixture inputs and outputs define a bounded offline policy; request identity must accompany the decision.

Why this case matters

Models a redirect controller decision before following a target or exposing a redirect result.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
from urllib.parse import urlsplit, unquote, quote
import posixpath
import re
N = 1
observations = []
def solve(request, drained, remaining, reusable, closed, canceled, http2):
    return {'request': request, 'decision': [not drained, reusable and drained and not closed, not http2 and remaining > 0 and not reusable, http2 and remaining > 0, not canceled and not closed, 'eof' if remaining == 0 else 'pending', not closed, remaining if not drained else 0, 'stream' if http2 else 'connection', 'released' if closed else ('canceling' if canceled else 'owned')]} 
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve('/requests/' + str(N) + '/0', False, 8, True, False, False, False), {'request': '/requests/' + str(N) + '/0', 'decision': [True, False, False, False, True, 'pending', True, 8, 'connection', 'owned']})
check('fixture 2', solve('/requests/' + str(N) + '/1', True, 0, True, False, False, False), {'request': '/requests/' + str(N) + '/1', 'decision': [False, True, False, False, True, 'eof', True, 0, 'connection', 'owned']})
check('fixture 3', solve('/requests/' + str(N) + '/2', False, 3, False, False, False, False), {'request': '/requests/' + str(N) + '/2', 'decision': [True, False, True, False, True, 'pending', True, 3, 'connection', 'owned']})
check('fixture 4', solve('/requests/' + str(N) + '/3', False, 5, True, False, True, True), {'request': '/requests/' + str(N) + '/3', 'decision': [True, False, False, True, False, 'pending', True, 5, 'stream', 'canceling']})
check('fixture 5', solve('/requests/' + str(N) + '/4', True, 0, True, True, False, True), {'request': '/requests/' + str(N) + '/4', 'decision': [False, False, False, False, False, 'eof', False, 0, 'stream', 'released']})
check('fixture 6', solve('/requests/' + str(N) + '/5', False, 0, False, True, True, False), {'request': '/requests/' + str(N) + '/5', 'decision': [False, False, False, False, False, 'eof', False, 0, 'connection', 'released']})
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 fixtureActualExpectedOutcome
fixture 1{'decision': [True, False, False, False, True, 'pending', True, 8, 'connection', 'owned'], 'request': '/requests/1/0'}{'decision': [True, False, False, False, True, 'pending', True, 8, 'connection', 'owned'], 'request': '/requests/1/0'}Passed
fixture 2{'decision': [False, True, False, False, True, 'eof', True, 0, 'connection', 'owned'], 'request': '/requests/1/1'}{'decision': [False, True, False, False, True, 'eof', True, 0, 'connection', 'owned'], 'request': '/requests/1/1'}Passed
fixture 3{'decision': [True, False, True, False, True, 'pending', True, 3, 'connection', 'owned'], 'request': '/requests/1/2'}{'decision': [True, False, True, False, True, 'pending', True, 3, 'connection', 'owned'], 'request': '/requests/1/2'}Passed
fixture 4{'decision': [True, False, False, True, False, 'pending', True, 5, 'stream', 'canceling'], 'request': '/requests/1/3'}{'decision': [True, False, False, True, False, 'pending', True, 5, 'stream', 'canceling'], 'request': '/requests/1/3'}Passed
fixture 5{'decision': [False, False, False, False, False, 'eof', False, 0, 'stream', 'released'], 'request': '/requests/1/4'}{'decision': [False, False, False, False, False, 'eof', False, 0, 'stream', 'released'], 'request': '/requests/1/4'}Passed
fixture 6{'decision': [True, False, False, False, False, 'eof', False, 0, 'connection', 'released'], 'request': '/requests/1/5'}{'decision': [False, False, False, False, False, 'eof', False, 0, 'connection', 'released'], 'request': '/requests/1/5'}Failed

SHA-256 / e3ca61ca10baa964ecc44a60cb37399f29269a1db8e644bbe0f69be858cd4adc

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
from urllib.parse import urlsplit, unquote, quote
import posixpath
import re
N = 1
observations = []
def solve(request, drained, remaining, reusable, closed, canceled, http2):
    return {'request': request, 'decision': [remaining >= 0, reusable and drained and not closed, not http2 and remaining > 0 and not reusable, http2 and remaining > 0, not canceled and not closed, 'eof' if remaining == 0 else 'pending', not closed, remaining if not drained else 0, 'stream' if http2 else 'connection', 'released' if closed else ('canceling' if canceled else 'owned')]} 
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve('/requests/' + str(N) + '/0', False, 8, True, False, False, False), {'request': '/requests/' + str(N) + '/0', 'decision': [True, False, False, False, True, 'pending', True, 8, 'connection', 'owned']})
check('fixture 2', solve('/requests/' + str(N) + '/1', True, 0, True, False, False, False), {'request': '/requests/' + str(N) + '/1', 'decision': [False, True, False, False, True, 'eof', True, 0, 'connection', 'owned']})
check('fixture 3', solve('/requests/' + str(N) + '/2', False, 3, False, False, False, False), {'request': '/requests/' + str(N) + '/2', 'decision': [True, False, True, False, True, 'pending', True, 3, 'connection', 'owned']})
check('fixture 4', solve('/requests/' + str(N) + '/3', False, 5, True, False, True, True), {'request': '/requests/' + str(N) + '/3', 'decision': [True, False, False, True, False, 'pending', True, 5, 'stream', 'canceling']})
check('fixture 5', solve('/requests/' + str(N) + '/4', True, 0, True, True, False, True), {'request': '/requests/' + str(N) + '/4', 'decision': [False, False, False, False, False, 'eof', False, 0, 'stream', 'released']})
check('fixture 6', solve('/requests/' + str(N) + '/5', False, 0, False, True, True, False), {'request': '/requests/' + str(N) + '/5', 'decision': [False, False, False, False, False, 'eof', False, 0, 'connection', 'released']})
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 fixtureActualExpectedOutcome
fixture 1{'decision': [True, False, False, False, True, 'pending', True, 8, 'connection', 'owned'], 'request': '/requests/1/0'}{'decision': [True, False, False, False, True, 'pending', True, 8, 'connection', 'owned'], 'request': '/requests/1/0'}Passed
fixture 2{'decision': [True, True, False, False, True, 'eof', True, 0, 'connection', 'owned'], 'request': '/requests/1/1'}{'decision': [False, True, False, False, True, 'eof', True, 0, 'connection', 'owned'], 'request': '/requests/1/1'}Failed
fixture 3{'decision': [True, False, True, False, True, 'pending', True, 3, 'connection', 'owned'], 'request': '/requests/1/2'}{'decision': [True, False, True, False, True, 'pending', True, 3, 'connection', 'owned'], 'request': '/requests/1/2'}Passed
fixture 4{'decision': [True, False, False, True, False, 'pending', True, 5, 'stream', 'canceling'], 'request': '/requests/1/3'}{'decision': [True, False, False, True, False, 'pending', True, 5, 'stream', 'canceling'], 'request': '/requests/1/3'}Passed
fixture 5{'decision': [True, False, False, False, False, 'eof', False, 0, 'stream', 'released'], 'request': '/requests/1/4'}{'decision': [False, False, False, False, False, 'eof', False, 0, 'stream', 'released'], 'request': '/requests/1/4'}Failed
fixture 6{'decision': [True, False, False, False, False, 'eof', False, 0, 'connection', 'released'], 'request': '/requests/1/5'}{'decision': [False, False, False, False, False, 'eof', False, 0, 'connection', 'released'], 'request': '/requests/1/5'}Failed

SHA-256 / 560175f81d8ddc287ac5807f9d73b2d593fef3874560e525e5ce87c4eb931db9

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 6 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Sign in to the archive ↗

Verification & scope

Stipulated offline redirect policy, not a complete HTTP, browser, URL, cache, or security implementation. Numbered variants vary request correlation identity. 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 2026-09-29T14:41:31.704492+00:00.

Case digest / 1a6e32e29adb4f9d2198c51dda37b70c62d5754da0716a3423ad5dc7dbd56298