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FA-28811 / HTTP redirects / Open access

Apply post-redirect fragment navigation without altering request routing: empty anchor document top · case 01

Apply post-redirect fragment navigation without altering request routing: the empty anchor document top branch emits an incorrect decision.

Verified by executionVariant 1 · 10 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The empty-anchor-document-top decision uses 'not ids'; this violates the stipulated controller policy.

VERIFIED REPAIR

At this decision use "fragment == ''", preserving the other controller outputs.

Unsuccessful approach: The partial repair uses "fragment in ('','top')" and still fails an explicit boundary or control.

Case contract

Apply post-redirect fragment navigation without altering request routing. 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, fragment, ids, saved_scroll, restore, decoded, directive):
    return {'request': request, 'decision': [next((i for i,v in enumerate(ids) if v==fragment),None), unquote(fragment) if decoded else fragment, restore, saved_scroll if restore else 0, not ids, directive and fragment.startswith(":~:"), '', (unquote(fragment) if decoded else fragment) in ids, saved_scroll if fragment not in ids else 0, None if directive else fragment]} 
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve('/requests/' + str(N) + '/0', 'section', ['top', 'section', 'section'], 25, False, True, False), {'request': '/requests/' + str(N) + '/0', 'decision': [1, 'section', False, 0, False, False, '', True, 0, 'section']})
check('fixture 2', solve('/requests/' + str(N) + '/1', 'a%20b', ['a b', 'a%20b'], 40, False, True, False), {'request': '/requests/' + str(N) + '/1', 'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b']})
check('fixture 3', solve('/requests/' + str(N) + '/2', 'missing', ['top'], 15, True, False, False), {'request': '/requests/' + str(N) + '/2', 'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing']})
check('fixture 4', solve('/requests/' + str(N) + '/3', '', [], 0, False, True, False), {'request': '/requests/' + str(N) + '/3', 'decision': [None, '', False, 0, True, False, '', False, 0, '']})
check('fixture 5', solve('/requests/' + str(N) + '/4', 'top', ['x', 'top'], 80, False, False, False), {'request': '/requests/' + str(N) + '/4', 'decision': [1, 'top', False, 0, False, False, '', True, 0, 'top']})
check('fixture 6', solve('/requests/' + str(N) + '/5', ':~:text=hello', [':~:text=hello'], 5, False, False, True), {'request': '/requests/' + str(N) + '/5', 'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None]})
check('fixture 7', solve('/requests/' + str(N) + '/6', 'a%20b', ['a b'], 5, False, True, False), {'request': '/requests/' + str(N) + '/6', 'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b']})
check('fixture 8', solve('/requests/' + str(N) + '/7', 'x%20y', [], 6, False, False, False), {'request': '/requests/' + str(N) + '/7', 'decision': [None, 'x%20y', False, 0, False, False, '', False, 6, 'x%20y']})
check('fixture 9', solve('/requests/' + str(N) + '/8', ':~:text=no', [], 8, False, False, False), {'request': '/requests/' + str(N) + '/8', 'decision': [None, ':~:text=no', False, 0, False, False, '', False, 8, ':~:text=no']})
check('fixture 10', solve('/requests/' + str(N) + '/9', '', ['top'], 9, False, False, False), {'request': '/requests/' + str(N) + '/9', 'decision': [None, '', False, 0, True, False, '', False, 9, '']})
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': [1, 'section', False, 0, False, False, '', True, 0, 'section'], 'request': '/requests/1/0'}{'decision': [1, 'section', False, 0, False, False, '', True, 0, 'section'], 'request': '/requests/1/0'}Passed
fixture 2{'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b'], 'request': '/requests/1/1'}{'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b'], 'request': '/requests/1/1'}Passed
fixture 3{'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing'], 'request': '/requests/1/2'}{'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing'], 'request': '/requests/1/2'}Passed
fixture 4{'decision': [None, '', False, 0, True, False, '', False, 0, ''], 'request': '/requests/1/3'}{'decision': [None, '', False, 0, True, False, '', False, 0, ''], 'request': '/requests/1/3'}Passed
fixture 5{'decision': [1, 'top', False, 0, False, False, '', True, 0, 'top'], 'request': '/requests/1/4'}{'decision': [1, 'top', False, 0, False, False, '', True, 0, 'top'], 'request': '/requests/1/4'}Passed
fixture 6{'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None], 'request': '/requests/1/5'}{'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None], 'request': '/requests/1/5'}Passed
fixture 7{'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b'], 'request': '/requests/1/6'}{'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b'], 'request': '/requests/1/6'}Passed
fixture 8{'decision': [None, 'x%20y', False, 0, True, False, '', False, 6, 'x%20y'], 'request': '/requests/1/7'}{'decision': [None, 'x%20y', False, 0, False, False, '', False, 6, 'x%20y'], 'request': '/requests/1/7'}Failed
fixture 9{'decision': [None, ':~:text=no', False, 0, True, False, '', False, 8, ':~:text=no'], 'request': '/requests/1/8'}{'decision': [None, ':~:text=no', False, 0, False, False, '', False, 8, ':~:text=no'], 'request': '/requests/1/8'}Failed
fixture 10{'decision': [None, '', False, 0, False, False, '', False, 9, ''], 'request': '/requests/1/9'}{'decision': [None, '', False, 0, True, False, '', False, 9, ''], 'request': '/requests/1/9'}Failed

SHA-256 / 9130b56d97ca6311c4d175f8e99fbcf1901ff5048f077d8620e16341f2451463

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, fragment, ids, saved_scroll, restore, decoded, directive):
    return {'request': request, 'decision': [next((i for i,v in enumerate(ids) if v==fragment),None), unquote(fragment) if decoded else fragment, restore, saved_scroll if restore else 0, fragment in ('','top'), directive and fragment.startswith(":~:"), '', (unquote(fragment) if decoded else fragment) in ids, saved_scroll if fragment not in ids else 0, None if directive else fragment]} 
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve('/requests/' + str(N) + '/0', 'section', ['top', 'section', 'section'], 25, False, True, False), {'request': '/requests/' + str(N) + '/0', 'decision': [1, 'section', False, 0, False, False, '', True, 0, 'section']})
check('fixture 2', solve('/requests/' + str(N) + '/1', 'a%20b', ['a b', 'a%20b'], 40, False, True, False), {'request': '/requests/' + str(N) + '/1', 'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b']})
check('fixture 3', solve('/requests/' + str(N) + '/2', 'missing', ['top'], 15, True, False, False), {'request': '/requests/' + str(N) + '/2', 'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing']})
check('fixture 4', solve('/requests/' + str(N) + '/3', '', [], 0, False, True, False), {'request': '/requests/' + str(N) + '/3', 'decision': [None, '', False, 0, True, False, '', False, 0, '']})
check('fixture 5', solve('/requests/' + str(N) + '/4', 'top', ['x', 'top'], 80, False, False, False), {'request': '/requests/' + str(N) + '/4', 'decision': [1, 'top', False, 0, False, False, '', True, 0, 'top']})
check('fixture 6', solve('/requests/' + str(N) + '/5', ':~:text=hello', [':~:text=hello'], 5, False, False, True), {'request': '/requests/' + str(N) + '/5', 'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None]})
check('fixture 7', solve('/requests/' + str(N) + '/6', 'a%20b', ['a b'], 5, False, True, False), {'request': '/requests/' + str(N) + '/6', 'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b']})
check('fixture 8', solve('/requests/' + str(N) + '/7', 'x%20y', [], 6, False, False, False), {'request': '/requests/' + str(N) + '/7', 'decision': [None, 'x%20y', False, 0, False, False, '', False, 6, 'x%20y']})
check('fixture 9', solve('/requests/' + str(N) + '/8', ':~:text=no', [], 8, False, False, False), {'request': '/requests/' + str(N) + '/8', 'decision': [None, ':~:text=no', False, 0, False, False, '', False, 8, ':~:text=no']})
check('fixture 10', solve('/requests/' + str(N) + '/9', '', ['top'], 9, False, False, False), {'request': '/requests/' + str(N) + '/9', 'decision': [None, '', False, 0, True, False, '', False, 9, '']})
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': [1, 'section', False, 0, False, False, '', True, 0, 'section'], 'request': '/requests/1/0'}{'decision': [1, 'section', False, 0, False, False, '', True, 0, 'section'], 'request': '/requests/1/0'}Passed
fixture 2{'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b'], 'request': '/requests/1/1'}{'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b'], 'request': '/requests/1/1'}Passed
fixture 3{'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing'], 'request': '/requests/1/2'}{'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing'], 'request': '/requests/1/2'}Passed
fixture 4{'decision': [None, '', False, 0, True, False, '', False, 0, ''], 'request': '/requests/1/3'}{'decision': [None, '', False, 0, True, False, '', False, 0, ''], 'request': '/requests/1/3'}Passed
fixture 5{'decision': [1, 'top', False, 0, True, False, '', True, 0, 'top'], 'request': '/requests/1/4'}{'decision': [1, 'top', False, 0, False, False, '', True, 0, 'top'], 'request': '/requests/1/4'}Failed
fixture 6{'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None], 'request': '/requests/1/5'}{'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None], 'request': '/requests/1/5'}Passed
fixture 7{'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b'], 'request': '/requests/1/6'}{'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b'], 'request': '/requests/1/6'}Passed
fixture 8{'decision': [None, 'x%20y', False, 0, False, False, '', False, 6, 'x%20y'], 'request': '/requests/1/7'}{'decision': [None, 'x%20y', False, 0, False, False, '', False, 6, 'x%20y'], 'request': '/requests/1/7'}Passed
fixture 9{'decision': [None, ':~:text=no', False, 0, False, False, '', False, 8, ':~:text=no'], 'request': '/requests/1/8'}{'decision': [None, ':~:text=no', False, 0, False, False, '', False, 8, ':~:text=no'], 'request': '/requests/1/8'}Passed
fixture 10{'decision': [None, '', False, 0, True, False, '', False, 9, ''], 'request': '/requests/1/9'}{'decision': [None, '', False, 0, True, False, '', False, 9, ''], 'request': '/requests/1/9'}Passed

SHA-256 / ed2ffc3e8a8edccd05570e905a6b64e6bb11f4c446370621f9bacbc67061fb71

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, fragment, ids, saved_scroll, restore, decoded, directive):
    return {'request': request, 'decision': [next((i for i,v in enumerate(ids) if v==fragment),None), unquote(fragment) if decoded else fragment, restore, saved_scroll if restore else 0, fragment == '', directive and fragment.startswith(":~:"), '', (unquote(fragment) if decoded else fragment) in ids, saved_scroll if fragment not in ids else 0, None if directive else fragment]} 
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve('/requests/' + str(N) + '/0', 'section', ['top', 'section', 'section'], 25, False, True, False), {'request': '/requests/' + str(N) + '/0', 'decision': [1, 'section', False, 0, False, False, '', True, 0, 'section']})
check('fixture 2', solve('/requests/' + str(N) + '/1', 'a%20b', ['a b', 'a%20b'], 40, False, True, False), {'request': '/requests/' + str(N) + '/1', 'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b']})
check('fixture 3', solve('/requests/' + str(N) + '/2', 'missing', ['top'], 15, True, False, False), {'request': '/requests/' + str(N) + '/2', 'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing']})
check('fixture 4', solve('/requests/' + str(N) + '/3', '', [], 0, False, True, False), {'request': '/requests/' + str(N) + '/3', 'decision': [None, '', False, 0, True, False, '', False, 0, '']})
check('fixture 5', solve('/requests/' + str(N) + '/4', 'top', ['x', 'top'], 80, False, False, False), {'request': '/requests/' + str(N) + '/4', 'decision': [1, 'top', False, 0, False, False, '', True, 0, 'top']})
check('fixture 6', solve('/requests/' + str(N) + '/5', ':~:text=hello', [':~:text=hello'], 5, False, False, True), {'request': '/requests/' + str(N) + '/5', 'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None]})
check('fixture 7', solve('/requests/' + str(N) + '/6', 'a%20b', ['a b'], 5, False, True, False), {'request': '/requests/' + str(N) + '/6', 'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b']})
check('fixture 8', solve('/requests/' + str(N) + '/7', 'x%20y', [], 6, False, False, False), {'request': '/requests/' + str(N) + '/7', 'decision': [None, 'x%20y', False, 0, False, False, '', False, 6, 'x%20y']})
check('fixture 9', solve('/requests/' + str(N) + '/8', ':~:text=no', [], 8, False, False, False), {'request': '/requests/' + str(N) + '/8', 'decision': [None, ':~:text=no', False, 0, False, False, '', False, 8, ':~:text=no']})
check('fixture 10', solve('/requests/' + str(N) + '/9', '', ['top'], 9, False, False, False), {'request': '/requests/' + str(N) + '/9', 'decision': [None, '', False, 0, True, False, '', False, 9, '']})
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': [1, 'section', False, 0, False, False, '', True, 0, 'section'], 'request': '/requests/1/0'}{'decision': [1, 'section', False, 0, False, False, '', True, 0, 'section'], 'request': '/requests/1/0'}Passed
fixture 2{'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b'], 'request': '/requests/1/1'}{'decision': [1, 'a b', False, 0, False, False, '', True, 0, 'a%20b'], 'request': '/requests/1/1'}Passed
fixture 3{'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing'], 'request': '/requests/1/2'}{'decision': [None, 'missing', True, 15, False, False, '', False, 15, 'missing'], 'request': '/requests/1/2'}Passed
fixture 4{'decision': [None, '', False, 0, True, False, '', False, 0, ''], 'request': '/requests/1/3'}{'decision': [None, '', False, 0, True, False, '', False, 0, ''], 'request': '/requests/1/3'}Passed
fixture 5{'decision': [1, 'top', False, 0, False, False, '', True, 0, 'top'], 'request': '/requests/1/4'}{'decision': [1, 'top', False, 0, False, False, '', True, 0, 'top'], 'request': '/requests/1/4'}Passed
fixture 6{'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None], 'request': '/requests/1/5'}{'decision': [0, ':~:text=hello', False, 0, False, True, '', True, 0, None], 'request': '/requests/1/5'}Passed
fixture 7{'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b'], 'request': '/requests/1/6'}{'decision': [None, 'a b', False, 0, False, False, '', True, 5, 'a%20b'], 'request': '/requests/1/6'}Passed
fixture 8{'decision': [None, 'x%20y', False, 0, False, False, '', False, 6, 'x%20y'], 'request': '/requests/1/7'}{'decision': [None, 'x%20y', False, 0, False, False, '', False, 6, 'x%20y'], 'request': '/requests/1/7'}Passed
fixture 9{'decision': [None, ':~:text=no', False, 0, False, False, '', False, 8, ':~:text=no'], 'request': '/requests/1/8'}{'decision': [None, ':~:text=no', False, 0, False, False, '', False, 8, ':~:text=no'], 'request': '/requests/1/8'}Passed
fixture 10{'decision': [None, '', False, 0, True, False, '', False, 9, ''], 'request': '/requests/1/9'}{'decision': [None, '', False, 0, True, False, '', False, 9, ''], 'request': '/requests/1/9'}Passed

SHA-256 / 39ae446f68cbad868a78946d6281bf497fd30a16480f52194b2e54b2ba77b2aa

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 2026-09-29T14:41:37.254721+00:00.

Case digest / a49b29de653d1f1d9bf33a89e2b549c8080da848bf1c2c8354264bbe6a38b25f