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FA-28051 / HTTP redirects / Open access

Keep encoded path structure distinct from redirect routing structure: literal plus preservation · case 01

Keep encoded path structure distinct from redirect routing structure: the literal plus preservation branch emits an incorrect decision.

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

ROOT CAUSE

The literal-plus-preservation decision uses "path.replace('+',' ').replace('%20',' ')"; this violates the stipulated controller policy.

VERIFIED REPAIR

At this decision use "path.replace('%20',' ')", preserving the other controller outputs.

Unsuccessful approach: The partial repair uses "path.replace('+',' ')" and still fails an explicit boundary or control.

Case contract

Keep encoded path structure distinct from redirect routing structure. 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, path):
    return {'request': request, 'decision': [path.split('/'), path.partition('?')[0], path.replace('+',' ').replace('%20',' '), unquote(path), [p for p in path.split('/') if p in ('.','..')]]} 
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve('/requests/' + str(N) + '/0', '/a%2Fb/%252F'), {'request': '/requests/' + str(N) + '/0', 'decision': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []]})
check('fixture 2', solve('/requests/' + str(N) + '/1', '/a+b/c%20d'), {'request': '/requests/' + str(N) + '/1', 'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a+b/c d', '/a+b/c d', []]})
check('fixture 3', solve('/requests/' + str(N) + '/2', '/a?x=1'), {'request': '/requests/' + str(N) + '/2', 'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []]})
check('fixture 4', solve('/requests/' + str(N) + '/3', '/x/../y/./z'), {'request': '/requests/' + str(N) + '/3', 'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']]})
check('fixture 5', solve('/requests/' + str(N) + '/4', '/v1.2/%2e%2e/a'), {'request': '/requests/' + str(N) + '/4', 'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []]})
check('fixture 6', solve('/requests/' + str(N) + '/5', '/'), {'request': '/requests/' + str(N) + '/5', 'decision': [['', ''], '/', '/', '/', []]})
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': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []], 'request': '/requests/1/0'}{'decision': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []], 'request': '/requests/1/0'}Passed
fixture 2{'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a b/c d', '/a+b/c d', []], 'request': '/requests/1/1'}{'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a+b/c d', '/a+b/c d', []], 'request': '/requests/1/1'}Failed
fixture 3{'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []], 'request': '/requests/1/2'}{'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []], 'request': '/requests/1/2'}Passed
fixture 4{'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']], 'request': '/requests/1/3'}{'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']], 'request': '/requests/1/3'}Passed
fixture 5{'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []], 'request': '/requests/1/4'}{'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []], 'request': '/requests/1/4'}Passed
fixture 6{'decision': [['', ''], '/', '/', '/', []], 'request': '/requests/1/5'}{'decision': [['', ''], '/', '/', '/', []], 'request': '/requests/1/5'}Passed

SHA-256 / 4c8849fd123906734eb28157ecacae44ab08c54b5a4ffb54f29f1ac29b8e7abb

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, path):
    return {'request': request, 'decision': [path.split('/'), path.partition('?')[0], path.replace('+',' '), unquote(path), [p for p in path.split('/') if p in ('.','..')]]} 
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve('/requests/' + str(N) + '/0', '/a%2Fb/%252F'), {'request': '/requests/' + str(N) + '/0', 'decision': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []]})
check('fixture 2', solve('/requests/' + str(N) + '/1', '/a+b/c%20d'), {'request': '/requests/' + str(N) + '/1', 'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a+b/c d', '/a+b/c d', []]})
check('fixture 3', solve('/requests/' + str(N) + '/2', '/a?x=1'), {'request': '/requests/' + str(N) + '/2', 'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []]})
check('fixture 4', solve('/requests/' + str(N) + '/3', '/x/../y/./z'), {'request': '/requests/' + str(N) + '/3', 'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']]})
check('fixture 5', solve('/requests/' + str(N) + '/4', '/v1.2/%2e%2e/a'), {'request': '/requests/' + str(N) + '/4', 'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []]})
check('fixture 6', solve('/requests/' + str(N) + '/5', '/'), {'request': '/requests/' + str(N) + '/5', 'decision': [['', ''], '/', '/', '/', []]})
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': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []], 'request': '/requests/1/0'}{'decision': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []], 'request': '/requests/1/0'}Passed
fixture 2{'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a b/c%20d', '/a+b/c d', []], 'request': '/requests/1/1'}{'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a+b/c d', '/a+b/c d', []], 'request': '/requests/1/1'}Failed
fixture 3{'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []], 'request': '/requests/1/2'}{'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []], 'request': '/requests/1/2'}Passed
fixture 4{'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']], 'request': '/requests/1/3'}{'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']], 'request': '/requests/1/3'}Passed
fixture 5{'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []], 'request': '/requests/1/4'}{'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []], 'request': '/requests/1/4'}Passed
fixture 6{'decision': [['', ''], '/', '/', '/', []], 'request': '/requests/1/5'}{'decision': [['', ''], '/', '/', '/', []], 'request': '/requests/1/5'}Passed

SHA-256 / 4f2c16669133f83e55008061e14851b22645c386589e05acfd27351239f095f6

3 / The verified repair

Exit 0
"""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, path):
    return {'request': request, 'decision': [path.split('/'), path.partition('?')[0], path.replace('%20',' '), unquote(path), [p for p in path.split('/') if p in ('.','..')]]} 
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve('/requests/' + str(N) + '/0', '/a%2Fb/%252F'), {'request': '/requests/' + str(N) + '/0', 'decision': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []]})
check('fixture 2', solve('/requests/' + str(N) + '/1', '/a+b/c%20d'), {'request': '/requests/' + str(N) + '/1', 'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a+b/c d', '/a+b/c d', []]})
check('fixture 3', solve('/requests/' + str(N) + '/2', '/a?x=1'), {'request': '/requests/' + str(N) + '/2', 'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []]})
check('fixture 4', solve('/requests/' + str(N) + '/3', '/x/../y/./z'), {'request': '/requests/' + str(N) + '/3', 'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']]})
check('fixture 5', solve('/requests/' + str(N) + '/4', '/v1.2/%2e%2e/a'), {'request': '/requests/' + str(N) + '/4', 'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []]})
check('fixture 6', solve('/requests/' + str(N) + '/5', '/'), {'request': '/requests/' + str(N) + '/5', 'decision': [['', ''], '/', '/', '/', []]})
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': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []], 'request': '/requests/1/0'}{'decision': [['', 'a%2Fb', '%252F'], '/a%2Fb/%252F', '/a%2Fb/%252F', '/a/b/%2F', []], 'request': '/requests/1/0'}Passed
fixture 2{'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a+b/c d', '/a+b/c d', []], 'request': '/requests/1/1'}{'decision': [['', 'a+b', 'c%20d'], '/a+b/c%20d', '/a+b/c d', '/a+b/c d', []], 'request': '/requests/1/1'}Passed
fixture 3{'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []], 'request': '/requests/1/2'}{'decision': [['', 'a?x=1'], '/a', '/a?x=1', '/a?x=1', []], 'request': '/requests/1/2'}Passed
fixture 4{'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']], 'request': '/requests/1/3'}{'decision': [['', 'x', '..', 'y', '.', 'z'], '/x/../y/./z', '/x/../y/./z', '/x/../y/./z', ['..', '.']], 'request': '/requests/1/3'}Passed
fixture 5{'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []], 'request': '/requests/1/4'}{'decision': [['', 'v1.2', '%2e%2e', 'a'], '/v1.2/%2e%2e/a', '/v1.2/%2e%2e/a', '/v1.2/../a', []], 'request': '/requests/1/4'}Passed
fixture 6{'decision': [['', ''], '/', '/', '/', []], 'request': '/requests/1/5'}{'decision': [['', ''], '/', '/', '/', []], 'request': '/requests/1/5'}Passed

SHA-256 / 788120f024b2a34950b3dfef6621e779ac2109d0dba4a5ac1a15abb6b8257926

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 2026-09-29T14:41:30.530377+00:00.

Case digest / bfcc71aa661442956316348dbbfbdf4cf9b2b355b2cbfa4423bcd5cf6eca5294