FA-5231 / Exception flow / Open access

Exception chaining metadata: Raises the wrapper without its requested explicit cause · case 01

Raises the wrapper without its requested explicit cause and changes the required Python-language result.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Raises the wrapper without its requested explicit cause. The executable reproducer isolates this operation from the rest of the contract.

THE FAILURE

Raises the wrapper without its requested explicit cause. The executable reproducer isolates this operation from the rest of the contract.

Unsuccessful approach: The alternative still fails because it leaves implicit context visible when from-None suppression was requested.

Case contract

Wrap ValueError in RuntimeError with implicit, explicit, or from-None chaining. Return [error type,cause type or None,context type or None,suppress-context flag]. Suppressing displayed context does not erase __context__. Inputs use the finite Python types shown in the fixtures. An error string denotes the specified caught exception, not an unhandled process failure.

Why this case matters

Runs Python standard-library language operations in a deterministic local reproducer. Literal expected answers are authored independently. Related defects share an evaluation group to avoid benchmark split leakage.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(mode):
    try:
        try:
            raise ValueError('original')
        except ValueError as original:
            error=RuntimeError('wrapper')
            if mode=='explicit':
                raise error
            elif mode=='suppressed':
                raise error from None
            else:
                raise error
    except BaseException as caught:
        pass
        return [type(caught).__name__, None if caught.__cause__ is None else type(caught.__cause__).__name__, None if caught.__context__ is None else type(caught.__context__).__name__, caught.__suppress_context__]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('explicit cause', solve('explicit'), ['RuntimeError', 'ValueError', 'ValueError', True])
check('suppressed display', solve('suppressed'), ['RuntimeError', None, 'ValueError', True])
check('implicit context', solve('implicit'), ['RuntimeError', None, 'ValueError', False])
check('default path remains implicit', solve('other'), ['RuntimeError', None, 'ValueError', False])
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
explicit cause	`['RuntimeError', None, 'ValueError', False]`	`['RuntimeError', 'ValueError', 'ValueError', True]`	Failed
suppressed display	`['RuntimeError', None, 'ValueError', True]`	`['RuntimeError', None, 'ValueError', True]`	Passed
implicit context	`['RuntimeError', None, 'ValueError', False]`	`['RuntimeError', None, 'ValueError', False]`	Passed
default path remains implicit	`['RuntimeError', None, 'ValueError', False]`	`['RuntimeError', None, 'ValueError', False]`	Passed

SHA-256 / a8b189773a9846614a97a77a4623d5fac339516dde46bb430efc4fdf6f5f14c7

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(mode):
    try:
        try:
            raise ValueError('original')
        except ValueError as original:
            error=RuntimeError('wrapper')
            if mode=='explicit':
                raise error from original
            elif mode=='suppressed':
                raise error
            else:
                raise error
    except BaseException as caught:
        pass
        return [type(caught).__name__, None if caught.__cause__ is None else type(caught.__cause__).__name__, None if caught.__context__ is None else type(caught.__context__).__name__, caught.__suppress_context__]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('explicit cause', solve('explicit'), ['RuntimeError', 'ValueError', 'ValueError', True])
check('suppressed display', solve('suppressed'), ['RuntimeError', None, 'ValueError', True])
check('implicit context', solve('implicit'), ['RuntimeError', None, 'ValueError', False])
check('default path remains implicit', solve('other'), ['RuntimeError', None, 'ValueError', False])
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
explicit cause	`['RuntimeError', 'ValueError', 'ValueError', True]`	`['RuntimeError', 'ValueError', 'ValueError', True]`	Passed
suppressed display	`['RuntimeError', None, 'ValueError', False]`	`['RuntimeError', None, 'ValueError', True]`	Failed
implicit context	`['RuntimeError', None, 'ValueError', False]`	`['RuntimeError', None, 'ValueError', False]`	Passed
default path remains implicit	`['RuntimeError', None, 'ValueError', False]`	`['RuntimeError', None, 'ValueError', False]`	Passed

SHA-256 / f07726ef7355c01b0cd1097f2da3deb21d5c5aa6b6e116b9e1e5bc8a9b7be607

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 4 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.

Verification & scope

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 2026-09-29T14:37:47.624319+00:00.

Case digest / 0fa980d22008aca38be388e80bb6e34a68eb34d56051509662d544193a83b64f