FA-26416 / HTTP ranges / Open access
Accept-Ranges reflects the chosen representation source capability · case 01
Accept-Ranges reflects the chosen representation source capability.
ROOT CAUSE
The range-unit-capability-advertisement decision uses return "bytes" if static_seekable else "none".
VERIFIED REPAIR
Apply the bounded decision exactly: return "bytes" if (dynamic_seekable if selected_dynamic else static_seekable) else "none"
Unsuccessful approach: The partial repair uses return "bytes" if static_seekable or dynamic_seekable else "none", which still violates the stated contract.
Case contract
Local advertisement is bytes only when the selected source supports seek. A dynamic selection uses its own capability, not the static source capability.
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(static_seekable, selected_dynamic, dynamic_seekable):
return "bytes" if static_seekable else "none"
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('range-unit-capability-advertisement fixture 0', solve(True,True,False), "none")
check('range-unit-capability-advertisement fixture 1', solve(False,False,True), "none")
check('range-unit-capability-advertisement fixture 2', solve(False,True,True), "bytes")
check('range-unit-capability-advertisement fixture 3', solve(True,False,False), "bytes")
check('range-unit-capability-advertisement fixture 4', solve(False,True,False), "none")
check('range-unit-capability-advertisement fixture 5', solve(True,True,True), "bytes")
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 |
|---|---|---|---|
| range-unit-capability-advertisement fixture 0 | bytes | none | Failed |
| range-unit-capability-advertisement fixture 1 | none | none | Passed |
| range-unit-capability-advertisement fixture 2 | none | bytes | Failed |
| range-unit-capability-advertisement fixture 3 | bytes | bytes | Passed |
| range-unit-capability-advertisement fixture 4 | none | none | Passed |
| range-unit-capability-advertisement fixture 5 | bytes | bytes | Passed |
SHA-256 / 20a8755c51340cb2a9d3d38f574a070504f031f81f9d3f08cf0817b3265f201c
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(static_seekable, selected_dynamic, dynamic_seekable):
return "bytes" if static_seekable or dynamic_seekable else "none"
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('range-unit-capability-advertisement fixture 0', solve(True,True,False), "none")
check('range-unit-capability-advertisement fixture 1', solve(False,False,True), "none")
check('range-unit-capability-advertisement fixture 2', solve(False,True,True), "bytes")
check('range-unit-capability-advertisement fixture 3', solve(True,False,False), "bytes")
check('range-unit-capability-advertisement fixture 4', solve(False,True,False), "none")
check('range-unit-capability-advertisement fixture 5', solve(True,True,True), "bytes")
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 |
|---|---|---|---|
| range-unit-capability-advertisement fixture 0 | bytes | none | Failed |
| range-unit-capability-advertisement fixture 1 | bytes | none | Failed |
| range-unit-capability-advertisement fixture 2 | bytes | bytes | Passed |
| range-unit-capability-advertisement fixture 3 | bytes | bytes | Passed |
| range-unit-capability-advertisement fixture 4 | none | none | Passed |
| range-unit-capability-advertisement fixture 5 | bytes | bytes | Passed |
SHA-256 / e3c4f03cded4b0f47d5a6f8fb6a273488cd9677f809b313e90571b0cee87fbb9
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(static_seekable, selected_dynamic, dynamic_seekable):
return "bytes" if (dynamic_seekable if selected_dynamic else static_seekable) else "none"
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('range-unit-capability-advertisement fixture 0', solve(True,True,False), "none")
check('range-unit-capability-advertisement fixture 1', solve(False,False,True), "none")
check('range-unit-capability-advertisement fixture 2', solve(False,True,True), "bytes")
check('range-unit-capability-advertisement fixture 3', solve(True,False,False), "bytes")
check('range-unit-capability-advertisement fixture 4', solve(False,True,False), "none")
check('range-unit-capability-advertisement fixture 5', solve(True,True,True), "bytes")
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 |
|---|---|---|---|
| range-unit-capability-advertisement fixture 0 | none | none | Passed |
| range-unit-capability-advertisement fixture 1 | none | none | Passed |
| range-unit-capability-advertisement fixture 2 | bytes | bytes | Passed |
| range-unit-capability-advertisement fixture 3 | bytes | bytes | Passed |
| range-unit-capability-advertisement fixture 4 | none | none | Passed |
| range-unit-capability-advertisement fixture 5 | bytes | bytes | Passed |
SHA-256 / fb84962548aa8af71f2ca8a4c76b0e94dba946ca0f47358715e54825e357c1a6
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 2026-09-29T14:41:15.780019+00:00.
Case digest / e72b6d525a33359ba846a836e4a6cc32df148cd537b54033a64ef50a55a2821c