FAILURE MAP
← Case archive

FA-29696 / HTTP retries / Open access

Retry after consumer-visible response delivery: Partial response errors lose the actual HTTP response status · case 01

Partial response errors lose the actual HTTP response status

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

ROOT CAUSE

Partial response errors lose the actual HTTP response status

THE FAILURE

Partial response errors lose the actual HTTP response status

Unsuccessful approach: The attempted repair changes the faulty site to status=None but still violates a regression oracle.

Case contract

begin starts an attempt only while nonterminal, headers records a status, deliver(bytes) records irreversible delivery, fail allows retry only before any delivered bytes. A zero-byte delivery is reversible. finish terminally succeeds. cancel terminally cancels. New attempts reset their local status but never erase already exposed data. Return retry decisions and exposed byte count.

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):
    active=False; delivered=0; status=None; terminal=False; out=[]
    for e in events:
        if e[0]=='begin':
            if terminal: out.append('terminal'); continue
            active=True
            status=None
        elif e[0]=='headers' and active:
            status=200
        elif e[0]=='deliver' and active:
            delivered+=e[1]
        elif e[0]=='fail':
            if terminal: out.append('terminal'); continue
            if not active: out.append('inactive'); continue
            active=False
            if delivered>0:
                terminal=True
                out.append(['partial',status])
            else: out.append(['retry',status])
        elif e[0]=='finish' and active:
            terminal=True; active=False; out.append('success')
        elif e[0]=='cancel':
            terminal=True; active=False; out.append('cancelled')
    return [out,delivered]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('0', solve([]), [[],0])
check('1', solve([('fail',)]), [['inactive'],0])
check('2', solve([('begin',),('headers',503),('deliver',0),('fail',),('fail',),('begin',),('fail',)]), [[['retry',503],'inactive',['retry',None]],0])
check('3', solve([('begin',),('headers',200),('deliver',1),('deliver',0),('fail',),('begin',)]), [[['partial',200],'terminal'],1])
check('4', solve([('begin',),('headers',502),('deliver',N+2),('deliver',2),('fail',)]), [[['partial',502]],N+4])
check('5', solve([('begin',),('finish',),('begin',),('fail',)]), [['success','terminal','terminal'],0])
check('6', solve([('begin',),('cancel',),('begin',)]), [['cancelled','terminal'],0])
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][[], 0]Passed
1[['inactive'], 0][['inactive'], 0]Passed
2[[['retry', 200], 'inactive', ['retry', None]], 0][[['retry', 503], 'inactive', ['retry', None]], 0]Failed
3[[['partial', 200], 'terminal'], 1][[['partial', 200], 'terminal'], 1]Passed
4[[['partial', 200]], 5][[['partial', 502]], 5]Failed
5[['success', 'terminal', 'terminal'], 0][['success', 'terminal', 'terminal'], 0]Passed
6[['cancelled', 'terminal'], 0][['cancelled', 'terminal'], 0]Passed

SHA-256 / cf472ea52aeae4056bcf5c7a8c58eef0ff041ae609a03ee378370f00a2c10a3c

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(events):
    active=False; delivered=0; status=None; terminal=False; out=[]
    for e in events:
        if e[0]=='begin':
            if terminal: out.append('terminal'); continue
            active=True
            status=None
        elif e[0]=='headers' and active:
            status=None
        elif e[0]=='deliver' and active:
            delivered+=e[1]
        elif e[0]=='fail':
            if terminal: out.append('terminal'); continue
            if not active: out.append('inactive'); continue
            active=False
            if delivered>0:
                terminal=True
                out.append(['partial',status])
            else: out.append(['retry',status])
        elif e[0]=='finish' and active:
            terminal=True; active=False; out.append('success')
        elif e[0]=='cancel':
            terminal=True; active=False; out.append('cancelled')
    return [out,delivered]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('0', solve([]), [[],0])
check('1', solve([('fail',)]), [['inactive'],0])
check('2', solve([('begin',),('headers',503),('deliver',0),('fail',),('fail',),('begin',),('fail',)]), [[['retry',503],'inactive',['retry',None]],0])
check('3', solve([('begin',),('headers',200),('deliver',1),('deliver',0),('fail',),('begin',)]), [[['partial',200],'terminal'],1])
check('4', solve([('begin',),('headers',502),('deliver',N+2),('deliver',2),('fail',)]), [[['partial',502]],N+4])
check('5', solve([('begin',),('finish',),('begin',),('fail',)]), [['success','terminal','terminal'],0])
check('6', solve([('begin',),('cancel',),('begin',)]), [['cancelled','terminal'],0])
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][[], 0]Passed
1[['inactive'], 0][['inactive'], 0]Passed
2[[['retry', None], 'inactive', ['retry', None]], 0][[['retry', 503], 'inactive', ['retry', None]], 0]Failed
3[[['partial', None], 'terminal'], 1][[['partial', 200], 'terminal'], 1]Failed
4[[['partial', None]], 5][[['partial', 502]], 5]Failed
5[['success', 'terminal', 'terminal'], 0][['success', 'terminal', 'terminal'], 0]Passed
6[['cancelled', 'terminal'], 0][['cancelled', 'terminal'], 0]Passed

SHA-256 / ecc8e4ad6b38ab6d20c6073109262e74325a63819b4b7f247f6f60d3bda78ab0

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.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Sign in to the archive ↗

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 2026-09-29T14:41:46.006053+00:00.

Case digest / 4ed70d42ef9fe399b7e80e6048cc56f8b649b9b1ed5e9d4c0ec85dd1bd00d61a