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FA-26756 / HTTP ranges / Open access

An unsatisfied continuation proves completion only against equal known total length · case 01

An unsatisfied continuation proves completion only against equal known total length.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The resume-416-does-not-prove-completion decision uses return "complete".

THE FAILURE

The resume-416-does-not-prove-completion decision uses return "complete".

Unsuccessful approach: The partial repair uses return "complete" if returned_total is not None and saved_length>=returned_total else "restart", which still violates the stated contract.

Case contract

Return complete only if a known returned total exactly equals saved bytes; shorter or longer totals request restart; unknown totals remain unverified.

Why this case matters

Range responses combine representation identity, conditional requests, framing, and partial-object state.

1 / The failure

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

N = 1
observations = []
def solve(saved_length, returned_total):
    return "complete"
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('resume-416-does-not-prove-completion fixture 0', solve(N,N+1), "restart")
check('resume-416-does-not-prove-completion fixture 1', solve(N+1,N), "restart")
check('resume-416-does-not-prove-completion fixture 2', solve(N,N), "complete")
check('resume-416-does-not-prove-completion fixture 3', solve(N,None), "unverified")
check('resume-416-does-not-prove-completion fixture 4', solve(0,0), "complete")
check('resume-416-does-not-prove-completion fixture 5', solve(0,N), "restart")
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
resume-416-does-not-prove-completion fixture 0completerestartFailed
resume-416-does-not-prove-completion fixture 1completerestartFailed
resume-416-does-not-prove-completion fixture 2completecompletePassed
resume-416-does-not-prove-completion fixture 3completeunverifiedFailed
resume-416-does-not-prove-completion fixture 4completecompletePassed
resume-416-does-not-prove-completion fixture 5completerestartFailed

SHA-256 / bf91d6eac55c9edbaf1bd96d94a4cc8e817a7b01a42f7f866a714526509174be

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(saved_length, returned_total):
    return "complete" if returned_total is not None and saved_length>=returned_total else "restart"
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('resume-416-does-not-prove-completion fixture 0', solve(N,N+1), "restart")
check('resume-416-does-not-prove-completion fixture 1', solve(N+1,N), "restart")
check('resume-416-does-not-prove-completion fixture 2', solve(N,N), "complete")
check('resume-416-does-not-prove-completion fixture 3', solve(N,None), "unverified")
check('resume-416-does-not-prove-completion fixture 4', solve(0,0), "complete")
check('resume-416-does-not-prove-completion fixture 5', solve(0,N), "restart")
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
resume-416-does-not-prove-completion fixture 0restartrestartPassed
resume-416-does-not-prove-completion fixture 1completerestartFailed
resume-416-does-not-prove-completion fixture 2completecompletePassed
resume-416-does-not-prove-completion fixture 3restartunverifiedFailed
resume-416-does-not-prove-completion fixture 4completecompletePassed
resume-416-does-not-prove-completion fixture 5restartrestartPassed

SHA-256 / 0556a2170fa247f6fb9254e0f675f4693bde6be8ce5ac8a447730e9f431bf56b

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 6 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.

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Verification & scope

Deterministic simplified range service, with stipulated local policies and already parsed trusted inputs; not a complete HTTP implementation. 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 2026-09-29T14:41:18.789581+00:00.

Case digest / 324e748c9c04ddc0000bb69859717d1a82327a7ab134a19f363e88cfa7e7d92b