Handle a checker defect locally

Project overview and reading path

A boundary receives an unknown mapping. Valid Python extracts a text field, but Pyrefly 1.3.1 rejects its mapping pattern. The goal is to isolate the checker defect without weakening the application’s checks.

Reproduction

def record_name(payload: object) -> str | None:
    match payload:
        case {"name": str(name)}:
            return name.strip()
    return None


name = record_name({"name": " training "})

For {"name": " training "}, Python returns "training". The pinned checker reports not-callable at the case, referring to __getitem__ and Never. The object parameter isolates an unknown-library boundary; it is not a suggested application record type.

Scoped repair

def record_name(payload: object) -> str | None:
    match payload:
        # Pyrefly 1.3.1 mapping-pattern defect; remove once fixed.
        # pyrefly: ignore[not-callable]
        case {"name": str(name)}:
            return name.strip()
    return None


name = record_name({"name": " training "})

Only the reproduced diagnostic is suppressed. Unrelated bad assignments remain errors. The verification suite checks both facts on temporary inputs, along with the runtime result. An upgrade fixing the defect must trigger removal of the workaround.

Prefer a supported annotation or guard when it expresses the same contract clearly. Do not change accepted inputs, error behavior, or coercion just to satisfy one checker version. A suppression needs runtime evidence and a removal condition; unknown external schemas still need validation.