FA-23026 / Autocomplete interactions / Open access

Hierarchical path autocomplete: trailing slash is treated as an empty search with no suggestions · case 01

The empty-segment completion transition produces an incorrect observable state.

Verified by executionVariant 1 · 22 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

At path-completion/empty-segment, the implementation evaluates `None` instead of preserving the specified completion transition.

THE FAILURE

At path-completion/empty-segment, the implementation evaluates `None` instead of preserving the specified completion transition.

Unsuccessful approach: The attempted repair uses `d['path']`, which still violates a normal or boundary completion fixture.

Case contract

Path autocomplete treats the prefix before the last slash as lookup scope and replaces only the final segment. Directory acceptance appends a slash and keeps completion active; leaf acceptance commits. Empty final segments request children, and responses bind to the exact parent path.

Why this case matters

Autocomplete couples draft text, suggestion identity and asynchronous presentation; this bounded lifecycle model isolates one observable interaction defect.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(event, d):
    if event == 'lookup-parent': return d['parent']
    if event == 'lookup-query': return d['segment']
    if event == 'replace': return d['parent']+d['name']
    if event == 'directory-suffix': return d['name']+('/' if d['directory'] else '')
    if event == 'commit': return None if d['directory'] else d['parent']+d['name']
    if event == 'continue': return d['directory']
    if event == 'response-parent': return d['response_parent']==d['parent']
    if event == 'empty-segment': return None
    if event == 'next-scope': return d['parent']+d['name']+'/' if d['directory'] else None
    if event == 'leaf-continuation': return {'leaf':not d['directory'],'continue_at':d['parent']+d['name']+'/' if d['directory'] else None}
    return {'unchanged': True}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
normal = {'path':'docs/api/rea','parent':'docs/api/','segment':'rea','name':'readme','directory':False,'response_parent':'docs/','epoch':N,'selected':'old','separator':'/'}
boundary = {'path':'docs/','parent':'docs/','segment':'','name':'guide','directory':True,'response_parent':'docs/','epoch':N,'selected':None,'separator':'/'}
check('normal lookup-parent', solve('lookup-parent', normal), 'docs/api/')
check('boundary lookup-parent', solve('lookup-parent', boundary), 'docs/')
check('normal lookup-query', solve('lookup-query', normal), 'rea')
check('boundary lookup-query', solve('lookup-query', boundary), '')
check('normal replace', solve('replace', normal), 'docs/api/readme')
check('boundary replace', solve('replace', boundary), 'docs/guide')
check('normal directory-suffix', solve('directory-suffix', normal), 'readme')
check('boundary directory-suffix', solve('directory-suffix', boundary), 'guide/')
check('normal commit', solve('commit', normal), 'docs/api/readme')
check('boundary commit', solve('commit', boundary), None)
check('normal continue', solve('continue', normal), False)
check('boundary continue', solve('continue', boundary), True)
check('normal response-parent', solve('response-parent', normal), False)
check('boundary response-parent', solve('response-parent', boundary), True)
check('normal empty-segment', solve('empty-segment', normal), None)
check('boundary empty-segment', solve('empty-segment', boundary), 'docs/')
check('normal next-scope', solve('next-scope', normal), None)
check('boundary next-scope', solve('next-scope', boundary), 'docs/guide/')
check('normal leaf-continuation', solve('leaf-continuation', normal), {'leaf':True,'continue_at':None})
check('boundary leaf-continuation', solve('leaf-continuation', boundary), {'leaf':False,'continue_at':'docs/guide/'})
variant = dict(normal, **{'segment':'r'*N})
check('variant query or selection payload', solve('lookup-query', variant), 'r'*N)
check('unknown completion event', solve('unrecognized', normal), {'unchanged': True})
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
normal lookup-parent	`docs/api/`	`docs/api/`	Passed
boundary lookup-parent	`docs/`	`docs/`	Passed
normal lookup-query	`rea`	`rea`	Passed
boundary lookup-query			Passed
normal replace	`docs/api/readme`	`docs/api/readme`	Passed
boundary replace	`docs/guide`	`docs/guide`	Passed
normal directory-suffix	`readme`	`readme`	Passed
boundary directory-suffix	`guide/`	`guide/`	Passed
normal commit	`docs/api/readme`	`docs/api/readme`	Passed
boundary commit	`None`	`None`	Passed
normal continue	`False`	`False`	Passed
boundary continue	`True`	`True`	Passed
normal response-parent	`False`	`False`	Passed
boundary response-parent	`True`	`True`	Passed
normal empty-segment	`None`	`None`	Passed
boundary empty-segment	`None`	`docs/`	Failed
normal next-scope	`None`	`None`	Passed
boundary next-scope	`docs/guide/`	`docs/guide/`	Passed
normal leaf-continuation	`{'continue_at': None, 'leaf': True}`	`{'continue_at': None, 'leaf': True}`	Passed
boundary leaf-continuation	`{'continue_at': 'docs/guide/', 'leaf': False}`	`{'continue_at': 'docs/guide/', 'leaf': False}`	Passed
variant query or selection payload	`r`	`r`	Passed
unknown completion event	`{'unchanged': True}`	`{'unchanged': True}`	Passed

SHA-256 / d75fb002b73899c5a7f953d92aa83ca72eb427fc7e0a3ca3ab23ef51f414ded6

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(event, d):
    if event == 'lookup-parent': return d['parent']
    if event == 'lookup-query': return d['segment']
    if event == 'replace': return d['parent']+d['name']
    if event == 'directory-suffix': return d['name']+('/' if d['directory'] else '')
    if event == 'commit': return None if d['directory'] else d['parent']+d['name']
    if event == 'continue': return d['directory']
    if event == 'response-parent': return d['response_parent']==d['parent']
    if event == 'empty-segment': return d['path']
    if event == 'next-scope': return d['parent']+d['name']+'/' if d['directory'] else None
    if event == 'leaf-continuation': return {'leaf':not d['directory'],'continue_at':d['parent']+d['name']+'/' if d['directory'] else None}
    return {'unchanged': True}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
normal = {'path':'docs/api/rea','parent':'docs/api/','segment':'rea','name':'readme','directory':False,'response_parent':'docs/','epoch':N,'selected':'old','separator':'/'}
boundary = {'path':'docs/','parent':'docs/','segment':'','name':'guide','directory':True,'response_parent':'docs/','epoch':N,'selected':None,'separator':'/'}
check('normal lookup-parent', solve('lookup-parent', normal), 'docs/api/')
check('boundary lookup-parent', solve('lookup-parent', boundary), 'docs/')
check('normal lookup-query', solve('lookup-query', normal), 'rea')
check('boundary lookup-query', solve('lookup-query', boundary), '')
check('normal replace', solve('replace', normal), 'docs/api/readme')
check('boundary replace', solve('replace', boundary), 'docs/guide')
check('normal directory-suffix', solve('directory-suffix', normal), 'readme')
check('boundary directory-suffix', solve('directory-suffix', boundary), 'guide/')
check('normal commit', solve('commit', normal), 'docs/api/readme')
check('boundary commit', solve('commit', boundary), None)
check('normal continue', solve('continue', normal), False)
check('boundary continue', solve('continue', boundary), True)
check('normal response-parent', solve('response-parent', normal), False)
check('boundary response-parent', solve('response-parent', boundary), True)
check('normal empty-segment', solve('empty-segment', normal), None)
check('boundary empty-segment', solve('empty-segment', boundary), 'docs/')
check('normal next-scope', solve('next-scope', normal), None)
check('boundary next-scope', solve('next-scope', boundary), 'docs/guide/')
check('normal leaf-continuation', solve('leaf-continuation', normal), {'leaf':True,'continue_at':None})
check('boundary leaf-continuation', solve('leaf-continuation', boundary), {'leaf':False,'continue_at':'docs/guide/'})
variant = dict(normal, **{'segment':'r'*N})
check('variant query or selection payload', solve('lookup-query', variant), 'r'*N)
check('unknown completion event', solve('unrecognized', normal), {'unchanged': True})
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
normal lookup-parent	`docs/api/`	`docs/api/`	Passed
boundary lookup-parent	`docs/`	`docs/`	Passed
normal lookup-query	`rea`	`rea`	Passed
boundary lookup-query			Passed
normal replace	`docs/api/readme`	`docs/api/readme`	Passed
boundary replace	`docs/guide`	`docs/guide`	Passed
normal directory-suffix	`readme`	`readme`	Passed
boundary directory-suffix	`guide/`	`guide/`	Passed
normal commit	`docs/api/readme`	`docs/api/readme`	Passed
boundary commit	`None`	`None`	Passed
normal continue	`False`	`False`	Passed
boundary continue	`True`	`True`	Passed
normal response-parent	`False`	`False`	Passed
boundary response-parent	`True`	`True`	Passed
normal empty-segment	`docs/api/rea`	`None`	Failed
boundary empty-segment	`docs/`	`docs/`	Passed
normal next-scope	`None`	`None`	Passed
boundary next-scope	`docs/guide/`	`docs/guide/`	Passed
normal leaf-continuation	`{'continue_at': None, 'leaf': True}`	`{'continue_at': None, 'leaf': True}`	Passed
boundary leaf-continuation	`{'continue_at': 'docs/guide/', 'leaf': False}`	`{'continue_at': 'docs/guide/', 'leaf': False}`	Passed
variant query or selection payload	`r`	`r`	Passed
unknown completion event	`{'unchanged': True}`	`{'unchanged': True}`	Passed

SHA-256 / bb99b762dc8d5992cfea3199a4cd63f85fd62047cf8886782a354cea44e451a3

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 22 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.

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Verification & scope

Stipulated deterministic widget transition model; inputs are validated snapshots. It does not model browser event dispatch, network transport, or linguistic standards. 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 2026-09-29T14:40:43.963068+00:00.

Case digest / 0aef8df7eeca9a7898d02b8d37b5178aa7e50a455593b28b0928487f6c78e084