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FA-30391 / HTTP retries / Open access

Logical request deadline across retry phases: Cancel terminal violates retry transition semantics · case 01

Cancel terminal violates retry transition semantics

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

ROOT CAUSE

Cancel terminal violates retry transition semantics

THE FAILURE

Cancel terminal violates retry transition semantics

Unsuccessful approach: The attempted repair changes the faulty site to state='failed'; due=None but still violates a regression oracle.

Case contract

begin(now,budget) pins a logical deadline. advance(time) uses monotonic logical time. queue(delay) schedules retry only for live request, wake starts only after due and strictly before deadline, complete succeeds only for running attempt before deadline. finish/cancel are terminal. Admission at expired time reports expired and closes request; queue never extends deadline. Return scheduling/attempt dispositions.

Why this case matters

Offline deterministic model of HTTP request retries.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(events):
    now=0; deadline=0; due=None; state='idle'; out=[]
    for e in events:
        if e[0]=='begin':
            now=e[1]; deadline=now+e[2]; due=None; state='ready'
        elif e[0]=='advance': now=max(now,e[1])
        elif e[0]=='cancel': state='ready'; due=None
        elif e[0]=='queue':
            if state not in ('ready','failed'): out.append('blocked'); continue
            if now>=deadline: state='expired'; out.append('expired'); continue
            due=now+e[1]; state='queued'; out.append(['queued',due])
        elif e[0]=='wake':
            if state!='queued': out.append('blocked'); continue
            if now>=deadline: state='expired'; due=None; out.append('expired'); continue
            if now<due: out.append('early'); continue
            state='running'; due=None; out.append('started')
        elif e[0]=='fail':
            if state=='running': state='failed'
        elif e[0]=='complete':
            if state!='running': out.append('blocked'); continue
            if now>=deadline: state='expired'; out.append('expired'); continue
            state='done'; out.append('success')
    return [out,deadline,state]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('0', solve([]), [[],0,'idle'])
check('1', solve([('begin',N,5),('queue',2),('wake',),('advance',N+2),('wake',),('complete',),('queue',0)]), [[['queued',N+2],'early','started','success','blocked'],N+5,'done'])
check('2', solve([('begin',N,2),('queue',2),('advance',N+2),('wake',)]), [[['queued',N+2],'expired'],N+2,'expired'])
check('3', solve([('begin',N,2),('advance',N+2),('queue',0)]), [['expired'],N+2,'expired'])
check('4', solve([('begin',N,2),('queue',0),('wake',),('advance',N+2),('complete',)]), [[['queued',N],'started','expired'],N+2,'expired'])
check('5', solve([('begin',N,5),('queue',0),('wake',),('fail',),('queue',1),('advance',N+1),('wake',),('cancel',),('queue',0)]), [[['queued',N],'started',['queued',N+1],'started','blocked'],N+5,'cancelled'])
check('6', solve([('begin',N,2),('advance',N+3),('advance',N),('queue',0)]), [['expired'],N+2,'expired'])
check('7', solve([('begin',N,3),('cancel',),('fail',),('queue',0)]), [['blocked'],N+3,'cancelled'])
check('8', solve([('begin',N,5),('queue',0),('wake',),('fail',)]), [[['queued',N],'started'],N+5,'failed'])
check('9', solve([('begin',N,5),('cancel',),('wake',)]), [['blocked'],N+5,'cancelled'])
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
0[[], 0, 'idle'][[], 0, 'idle']Passed
1[[['queued', 3], 'early', 'started', 'success', 'blocked'], 6, 'done'][[['queued', 3], 'early', 'started', 'success', 'blocked'], 6, 'done']Passed
2[[['queued', 3], 'expired'], 3, 'expired'][[['queued', 3], 'expired'], 3, 'expired']Passed
3[['expired'], 3, 'expired'][['expired'], 3, 'expired']Passed
4[[['queued', 1], 'started', 'expired'], 3, 'expired'][[['queued', 1], 'started', 'expired'], 3, 'expired']Passed
5[[['queued', 1], 'started', ['queued', 2], 'started', ['queued', 2]], 6, 'queued'][[['queued', 1], 'started', ['queued', 2], 'started', 'blocked'], 6, 'cancelled']Failed
6[['expired'], 3, 'expired'][['expired'], 3, 'expired']Passed
7[[['queued', 1]], 4, 'queued'][['blocked'], 4, 'cancelled']Failed
8[[['queued', 1], 'started'], 6, 'failed'][[['queued', 1], 'started'], 6, 'failed']Passed
9[['blocked'], 6, 'ready'][['blocked'], 6, 'cancelled']Failed

SHA-256 / c0522de367fe57d78bf4369b1078af9b4a114e8d78f21aee3c7ab20ed9f516e3

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(events):
    now=0; deadline=0; due=None; state='idle'; out=[]
    for e in events:
        if e[0]=='begin':
            now=e[1]; deadline=now+e[2]; due=None; state='ready'
        elif e[0]=='advance': now=max(now,e[1])
        elif e[0]=='cancel': state='failed'; due=None
        elif e[0]=='queue':
            if state not in ('ready','failed'): out.append('blocked'); continue
            if now>=deadline: state='expired'; out.append('expired'); continue
            due=now+e[1]; state='queued'; out.append(['queued',due])
        elif e[0]=='wake':
            if state!='queued': out.append('blocked'); continue
            if now>=deadline: state='expired'; due=None; out.append('expired'); continue
            if now<due: out.append('early'); continue
            state='running'; due=None; out.append('started')
        elif e[0]=='fail':
            if state=='running': state='failed'
        elif e[0]=='complete':
            if state!='running': out.append('blocked'); continue
            if now>=deadline: state='expired'; out.append('expired'); continue
            state='done'; out.append('success')
    return [out,deadline,state]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('0', solve([]), [[],0,'idle'])
check('1', solve([('begin',N,5),('queue',2),('wake',),('advance',N+2),('wake',),('complete',),('queue',0)]), [[['queued',N+2],'early','started','success','blocked'],N+5,'done'])
check('2', solve([('begin',N,2),('queue',2),('advance',N+2),('wake',)]), [[['queued',N+2],'expired'],N+2,'expired'])
check('3', solve([('begin',N,2),('advance',N+2),('queue',0)]), [['expired'],N+2,'expired'])
check('4', solve([('begin',N,2),('queue',0),('wake',),('advance',N+2),('complete',)]), [[['queued',N],'started','expired'],N+2,'expired'])
check('5', solve([('begin',N,5),('queue',0),('wake',),('fail',),('queue',1),('advance',N+1),('wake',),('cancel',),('queue',0)]), [[['queued',N],'started',['queued',N+1],'started','blocked'],N+5,'cancelled'])
check('6', solve([('begin',N,2),('advance',N+3),('advance',N),('queue',0)]), [['expired'],N+2,'expired'])
check('7', solve([('begin',N,3),('cancel',),('fail',),('queue',0)]), [['blocked'],N+3,'cancelled'])
check('8', solve([('begin',N,5),('queue',0),('wake',),('fail',)]), [[['queued',N],'started'],N+5,'failed'])
check('9', solve([('begin',N,5),('cancel',),('wake',)]), [['blocked'],N+5,'cancelled'])
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
0[[], 0, 'idle'][[], 0, 'idle']Passed
1[[['queued', 3], 'early', 'started', 'success', 'blocked'], 6, 'done'][[['queued', 3], 'early', 'started', 'success', 'blocked'], 6, 'done']Passed
2[[['queued', 3], 'expired'], 3, 'expired'][[['queued', 3], 'expired'], 3, 'expired']Passed
3[['expired'], 3, 'expired'][['expired'], 3, 'expired']Passed
4[[['queued', 1], 'started', 'expired'], 3, 'expired'][[['queued', 1], 'started', 'expired'], 3, 'expired']Passed
5[[['queued', 1], 'started', ['queued', 2], 'started', ['queued', 2]], 6, 'queued'][[['queued', 1], 'started', ['queued', 2], 'started', 'blocked'], 6, 'cancelled']Failed
6[['expired'], 3, 'expired'][['expired'], 3, 'expired']Passed
7[[['queued', 1]], 4, 'queued'][['blocked'], 4, 'cancelled']Failed
8[[['queued', 1], 'started'], 6, 'failed'][[['queued', 1], 'started'], 6, 'failed']Passed
9[['blocked'], 6, 'failed'][['blocked'], 6, 'cancelled']Failed

SHA-256 / a7003dafd8f847d4350285d8e71be52a3108b374835bf37988898cbafe1c0764

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 10 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 bounded simulator, not a complete HTTP implementation or a standards conformance claim. 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 2026-09-29T14:41:53.013934+00:00.

Case digest / cd16ac445737ea030d4bc4cdb9e56cf858e4a837de46b1b1221897f3c7301154