FA-21966 / Autocomplete interactions / Open access
Completion debounce lifecycle: leading edge marks the previous query as already searched · case 01
The leading completion transition produces an incorrect observable state.
ROOT CAUSE
At debounce/leading, the implementation evaluates `{'sent':d['sent'],'epoch':d['epoch']}` instead of preserving the specified completion transition.
THE FAILURE
At debounce/leading, the implementation evaluates `{'sent':d['sent'],'epoch':d['epoch']}` instead of preserving the specified completion transition.
Unsuccessful approach: The attempted repair uses `{'sent':d['query'],'epoch':d['job_epoch']}`, which still violates a normal or boundary completion fixture.
Case contract
A new draft replaces the pending autocomplete job and its deadline. A deadline emits only its exact draft epoch; flush emits pending text once; cancellation discards pending text. Leading search marks its own query, and composition suspends timers. Time values are integer ticks.
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 == 'replace': return d['query']
if event == 'deadline': return d['now']+d['delay']
if event == 'expired': return d['pending'] if d['job_epoch']==d['epoch'] and d['now']>=d['deadline'] else None
if event == 'flush': return [d['pending']] if d['pending'] is not None else []
if event == 'cancel': return {'pending':None,'deadline':None}
if event == 'leading': return {'sent':d['sent'],'epoch':d['epoch']}
if event == 'suspend': return None if d['composing'] else d['deadline']
if event == 'duplicate': return d['query']==d['sent']
if event == 'after-flush': return {'pending':None,'sent':d['pending'] if d['pending'] is not None else d['sent']}
if event == 'retag': return {'job_epoch':d['epoch'],'query':d['query']}
return {'unchanged': True}
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
normal = {'query':'pea','pending':'pe','epoch':N,'job_epoch':N-1,'now':N*10,'delay':4,'deadline':N*10-1,'sent':'p','composing':True}
boundary = {'query':'','pending':None,'epoch':N,'job_epoch':N,'now':N*10,'delay':0,'deadline':N*10,'sent':'','composing':False}
check('normal replace', solve('replace', normal), 'pea')
check('boundary replace', solve('replace', boundary), '')
check('normal deadline', solve('deadline', normal), N*10+4)
check('boundary deadline', solve('deadline', boundary), N*10)
check('normal expired', solve('expired', normal), None)
check('boundary expired', solve('expired', boundary), None)
check('normal flush', solve('flush', normal), ['pe'])
check('boundary flush', solve('flush', boundary), [])
check('normal cancel', solve('cancel', normal), {'pending':None,'deadline':None})
check('boundary cancel', solve('cancel', boundary), {'pending':None,'deadline':None})
check('normal leading', solve('leading', normal), {'sent':'pea','epoch':N})
check('boundary leading', solve('leading', boundary), {'sent':'','epoch':N})
check('normal suspend', solve('suspend', normal), None)
check('boundary suspend', solve('suspend', boundary), N*10)
check('normal duplicate', solve('duplicate', normal), False)
check('boundary duplicate', solve('duplicate', boundary), True)
check('normal after-flush', solve('after-flush', normal), {'pending':None,'sent':'pe'})
check('boundary after-flush', solve('after-flush', boundary), {'pending':None,'sent':''})
check('normal retag', solve('retag', normal), {'job_epoch':N,'query':'pea'})
check('boundary retag', solve('retag', boundary), {'job_epoch':N,'query':''})
variant = dict(normal, **{'query':'q'*N})
check('variant query or selection payload', solve('replace', variant), 'q'*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 replace | pea | pea | Passed |
| boundary replace | | | Passed |
| normal deadline | 14 | 14 | Passed |
| boundary deadline | 10 | 10 | Passed |
| normal expired | None | None | Passed |
| boundary expired | None | None | Passed |
| normal flush | ['pe'] | ['pe'] | Passed |
| boundary flush | [] | [] | Passed |
| normal cancel | {'deadline': None, 'pending': None} | {'deadline': None, 'pending': None} | Passed |
| boundary cancel | {'deadline': None, 'pending': None} | {'deadline': None, 'pending': None} | Passed |
| normal leading | {'epoch': 1, 'sent': 'p'} | {'epoch': 1, 'sent': 'pea'} | Failed |
| boundary leading | {'epoch': 1, 'sent': ''} | {'epoch': 1, 'sent': ''} | Passed |
| normal suspend | None | None | Passed |
| boundary suspend | 10 | 10 | Passed |
| normal duplicate | False | False | Passed |
| boundary duplicate | True | True | Passed |
| normal after-flush | {'pending': None, 'sent': 'pe'} | {'pending': None, 'sent': 'pe'} | Passed |
| boundary after-flush | {'pending': None, 'sent': ''} | {'pending': None, 'sent': ''} | Passed |
| normal retag | {'job_epoch': 1, 'query': 'pea'} | {'job_epoch': 1, 'query': 'pea'} | Passed |
| boundary retag | {'job_epoch': 1, 'query': ''} | {'job_epoch': 1, 'query': ''} | Passed |
| variant query or selection payload | q | q | Passed |
| unknown completion event | {'unchanged': True} | {'unchanged': True} | Passed |
SHA-256 / c1134fe609ff703bb48e03afd125d56945b51089eeba11606cde5cbf65008578
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 == 'replace': return d['query']
if event == 'deadline': return d['now']+d['delay']
if event == 'expired': return d['pending'] if d['job_epoch']==d['epoch'] and d['now']>=d['deadline'] else None
if event == 'flush': return [d['pending']] if d['pending'] is not None else []
if event == 'cancel': return {'pending':None,'deadline':None}
if event == 'leading': return {'sent':d['query'],'epoch':d['job_epoch']}
if event == 'suspend': return None if d['composing'] else d['deadline']
if event == 'duplicate': return d['query']==d['sent']
if event == 'after-flush': return {'pending':None,'sent':d['pending'] if d['pending'] is not None else d['sent']}
if event == 'retag': return {'job_epoch':d['epoch'],'query':d['query']}
return {'unchanged': True}
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
normal = {'query':'pea','pending':'pe','epoch':N,'job_epoch':N-1,'now':N*10,'delay':4,'deadline':N*10-1,'sent':'p','composing':True}
boundary = {'query':'','pending':None,'epoch':N,'job_epoch':N,'now':N*10,'delay':0,'deadline':N*10,'sent':'','composing':False}
check('normal replace', solve('replace', normal), 'pea')
check('boundary replace', solve('replace', boundary), '')
check('normal deadline', solve('deadline', normal), N*10+4)
check('boundary deadline', solve('deadline', boundary), N*10)
check('normal expired', solve('expired', normal), None)
check('boundary expired', solve('expired', boundary), None)
check('normal flush', solve('flush', normal), ['pe'])
check('boundary flush', solve('flush', boundary), [])
check('normal cancel', solve('cancel', normal), {'pending':None,'deadline':None})
check('boundary cancel', solve('cancel', boundary), {'pending':None,'deadline':None})
check('normal leading', solve('leading', normal), {'sent':'pea','epoch':N})
check('boundary leading', solve('leading', boundary), {'sent':'','epoch':N})
check('normal suspend', solve('suspend', normal), None)
check('boundary suspend', solve('suspend', boundary), N*10)
check('normal duplicate', solve('duplicate', normal), False)
check('boundary duplicate', solve('duplicate', boundary), True)
check('normal after-flush', solve('after-flush', normal), {'pending':None,'sent':'pe'})
check('boundary after-flush', solve('after-flush', boundary), {'pending':None,'sent':''})
check('normal retag', solve('retag', normal), {'job_epoch':N,'query':'pea'})
check('boundary retag', solve('retag', boundary), {'job_epoch':N,'query':''})
variant = dict(normal, **{'query':'q'*N})
check('variant query or selection payload', solve('replace', variant), 'q'*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 replace | pea | pea | Passed |
| boundary replace | | | Passed |
| normal deadline | 14 | 14 | Passed |
| boundary deadline | 10 | 10 | Passed |
| normal expired | None | None | Passed |
| boundary expired | None | None | Passed |
| normal flush | ['pe'] | ['pe'] | Passed |
| boundary flush | [] | [] | Passed |
| normal cancel | {'deadline': None, 'pending': None} | {'deadline': None, 'pending': None} | Passed |
| boundary cancel | {'deadline': None, 'pending': None} | {'deadline': None, 'pending': None} | Passed |
| normal leading | {'epoch': 0, 'sent': 'pea'} | {'epoch': 1, 'sent': 'pea'} | Failed |
| boundary leading | {'epoch': 1, 'sent': ''} | {'epoch': 1, 'sent': ''} | Passed |
| normal suspend | None | None | Passed |
| boundary suspend | 10 | 10 | Passed |
| normal duplicate | False | False | Passed |
| boundary duplicate | True | True | Passed |
| normal after-flush | {'pending': None, 'sent': 'pe'} | {'pending': None, 'sent': 'pe'} | Passed |
| boundary after-flush | {'pending': None, 'sent': ''} | {'pending': None, 'sent': ''} | Passed |
| normal retag | {'job_epoch': 1, 'query': 'pea'} | {'job_epoch': 1, 'query': 'pea'} | Passed |
| boundary retag | {'job_epoch': 1, 'query': ''} | {'job_epoch': 1, 'query': ''} | Passed |
| variant query or selection payload | q | q | Passed |
| unknown completion event | {'unchanged': True} | {'unchanged': True} | Passed |
SHA-256 / fdda13236773fae0eaf6eed98d5186675c3bede84d162ea972ee078f258b6301
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.
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Sign in to the archive ↗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 2026-09-29T14:40:34.075620+00:00.
Case digest / 5ad27ee3ea32029854ea9418f8cc4e4222694f7d63a85021eab7b1207d3cd916