FA-29391 / HTTP retries / Open access

One-shot request body replay refusal: A fresh one-shot body inherits consumption from the previous request · case 01

A fresh one-shot body inherits consumption from the previous request

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

A fresh one-shot body inherits consumption from the previous request

THE FAILURE

A fresh one-shot body inherits consumption from the previous request

Unsuccessful approach: The attempted repair changes the faulty site to consumed = consumed failed but still violates a regression oracle.

Case contract

Events open, send(nonnegative bytes), fail(known_unprocessed bool), retry, succeed. State tracks whether any bytes were emitted by a one-shot stream. A failure known unprocessed does not restore consumed stream bytes. Only an open stream with zero consumed bytes may retry. Terminal success closes the logical request. Output one decision per retry and terminal success.

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):
    opened = False; consumed = 0; failed = False; terminal = False; out = []
    for e in events:
        if e[0] == 'open':
            opened = True
            consumed = 1
            failed = False
            terminal = False
        elif e[0] == 'send' and opened and not terminal:
            consumed += e[1]
        elif e[0] == 'fail' and opened and not terminal:
            failed = True
        elif e[0] == 'retry':
            if terminal:
                out.append('terminal')
            elif not opened:
                out.append('no-body')
            elif not failed:
                out.append('no-failure')
            elif consumed != 0:
                out.append('unreplayable')
            else:
                out.append('retry')
                failed = False
        elif e[0] == 'succeed' and opened and not terminal:
            terminal = True
            out.append('success')
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('0', solve([]), [])
check('1', solve([('retry',)]), ['no-body'])
check('2', solve([('open',),('retry',),('fail',True),('retry',),('retry',)]), ['no-failure','retry','no-failure'])
check('3', solve([('open',),('send',1),('send',0),('fail',True),('retry',)]), ['unreplayable'])
check('4', solve([('open',),('send',N),('fail',False),('retry',),('open',),('fail',False),('retry',)]), ['unreplayable','retry'])
check('5', solve([('open',),('succeed',),('retry',),('open',),('fail',True),('retry',)]), ['success','terminal','retry'])
check('6', solve([('open',),('send',0),('fail',False),('retry',),('succeed',),('retry',)]), ['retry','success','terminal'])
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
0	`[]`	`[]`	Passed
1	`['no-body']`	`['no-body']`	Passed
2	`['no-failure', 'unreplayable', 'unreplayable']`	`['no-failure', 'retry', 'no-failure']`	Failed
3	`['unreplayable']`	`['unreplayable']`	Passed
4	`['unreplayable', 'unreplayable']`	`['unreplayable', 'retry']`	Failed
5	`['success', 'terminal', 'unreplayable']`	`['success', 'terminal', 'retry']`	Failed
6	`['unreplayable', 'success', 'terminal']`	`['retry', 'success', 'terminal']`	Failed

SHA-256 / b2cc87faa13152bf52a6f6cd694d4a9467cb30f982121ea9ace7b128b72ea0a5

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(events):
    opened = False; consumed = 0; failed = False; terminal = False; out = []
    for e in events:
        if e[0] == 'open':
            opened = True
            consumed = consumed
            failed = False
            terminal = False
        elif e[0] == 'send' and opened and not terminal:
            consumed += e[1]
        elif e[0] == 'fail' and opened and not terminal:
            failed = True
        elif e[0] == 'retry':
            if terminal:
                out.append('terminal')
            elif not opened:
                out.append('no-body')
            elif not failed:
                out.append('no-failure')
            elif consumed != 0:
                out.append('unreplayable')
            else:
                out.append('retry')
                failed = False
        elif e[0] == 'succeed' and opened and not terminal:
            terminal = True
            out.append('success')
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('0', solve([]), [])
check('1', solve([('retry',)]), ['no-body'])
check('2', solve([('open',),('retry',),('fail',True),('retry',),('retry',)]), ['no-failure','retry','no-failure'])
check('3', solve([('open',),('send',1),('send',0),('fail',True),('retry',)]), ['unreplayable'])
check('4', solve([('open',),('send',N),('fail',False),('retry',),('open',),('fail',False),('retry',)]), ['unreplayable','retry'])
check('5', solve([('open',),('succeed',),('retry',),('open',),('fail',True),('retry',)]), ['success','terminal','retry'])
check('6', solve([('open',),('send',0),('fail',False),('retry',),('succeed',),('retry',)]), ['retry','success','terminal'])
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
0	`[]`	`[]`	Passed
1	`['no-body']`	`['no-body']`	Passed
2	`['no-failure', 'retry', 'no-failure']`	`['no-failure', 'retry', 'no-failure']`	Passed
3	`['unreplayable']`	`['unreplayable']`	Passed
4	`['unreplayable', 'unreplayable']`	`['unreplayable', 'retry']`	Failed
5	`['success', 'terminal', 'retry']`	`['success', 'terminal', 'retry']`	Passed
6	`['retry', 'success', 'terminal']`	`['retry', 'success', 'terminal']`	Passed

SHA-256 / 6b2dead26641de58490509037f95661f11ad7f1242fde48b1114f1210e12234f

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 7 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 2026-09-29T14:41:43.113706+00:00.

Case digest / 0dfded0ebb78120edac241f66379e3df471c8d871b8787fba884d2f3b7b0f689