FAILURE MAP
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FA-26551 / HTTP ranges / Open access

Partial-read progress advances from the selected absolute start · case 01

Partial-read progress advances from the selected absolute start.

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

ROOT CAUSE

The stream-progress-absolute-offset decision uses return delivered.

VERIFIED REPAIR

Apply the bounded decision exactly: return start+delivered

Unsuccessful approach: The partial repair uses return max(start,delivered), which still violates the stated contract.

Case contract

Return the next absolute representation offset start+delivered; delivered counts body bytes only.

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(start, delivered):
    return delivered
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('stream-progress-absolute-offset fixture 0', solve(2*N,N), 3*N)
check('stream-progress-absolute-offset fixture 1', solve(N,0), N)
check('stream-progress-absolute-offset fixture 2', solve(0,N), N)
check('stream-progress-absolute-offset fixture 3', solve(0,0), 0)
check('stream-progress-absolute-offset fixture 4', solve(N,2*N), 3*N)
check('stream-progress-absolute-offset fixture 5', solve(3*N,4*N), 7*N)
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
stream-progress-absolute-offset fixture 013Failed
stream-progress-absolute-offset fixture 101Failed
stream-progress-absolute-offset fixture 211Passed
stream-progress-absolute-offset fixture 300Passed
stream-progress-absolute-offset fixture 423Failed
stream-progress-absolute-offset fixture 547Failed

SHA-256 / 2ef4b322d1457fe5098ad73fdc5b188f9b7d90326fb3fadbb106ccbe7a69fa2c

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(start, delivered):
    return max(start,delivered)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('stream-progress-absolute-offset fixture 0', solve(2*N,N), 3*N)
check('stream-progress-absolute-offset fixture 1', solve(N,0), N)
check('stream-progress-absolute-offset fixture 2', solve(0,N), N)
check('stream-progress-absolute-offset fixture 3', solve(0,0), 0)
check('stream-progress-absolute-offset fixture 4', solve(N,2*N), 3*N)
check('stream-progress-absolute-offset fixture 5', solve(3*N,4*N), 7*N)
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
stream-progress-absolute-offset fixture 023Failed
stream-progress-absolute-offset fixture 111Passed
stream-progress-absolute-offset fixture 211Passed
stream-progress-absolute-offset fixture 300Passed
stream-progress-absolute-offset fixture 423Failed
stream-progress-absolute-offset fixture 547Failed

SHA-256 / 5bd49230c202a08e1aa8a92eb9c4a62d5fb7841d878d4451f651fd0d057b52f2

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(start, delivered):
    return start+delivered
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('stream-progress-absolute-offset fixture 0', solve(2*N,N), 3*N)
check('stream-progress-absolute-offset fixture 1', solve(N,0), N)
check('stream-progress-absolute-offset fixture 2', solve(0,N), N)
check('stream-progress-absolute-offset fixture 3', solve(0,0), 0)
check('stream-progress-absolute-offset fixture 4', solve(N,2*N), 3*N)
check('stream-progress-absolute-offset fixture 5', solve(3*N,4*N), 7*N)
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
stream-progress-absolute-offset fixture 033Passed
stream-progress-absolute-offset fixture 111Passed
stream-progress-absolute-offset fixture 211Passed
stream-progress-absolute-offset fixture 300Passed
stream-progress-absolute-offset fixture 433Passed
stream-progress-absolute-offset fixture 577Passed

SHA-256 / 77d9bb0e613af95debe606da22c005cef5f4b91ee3b7dbfa44d053340460c166

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 2026-09-29T14:41:16.932271+00:00.

Case digest / d9460f977c8462edadcec12b35d8ed817d02d3d9754cbf4c6ba032bb3f7cccc0