CancelProtection

    const CancelProtection = packed struct {
        user: Io.CancelProtection,
        acknowledged: bool,

        const unblocked: CancelProtection = .{ .user = .unblocked, .acknowledged = false };

        fn check(cancel_protection: CancelProtection) Io.CancelProtection {
            return @fromBackingInt(@intCast(@intFromBool(cancel_protection != unblocked)));
        }

        fn acknowledge(cancel_protection: *CancelProtection) void {
            assert(!cancel_protection.acknowledged);
            cancel_protection.acknowledged = true;
        }

        fn recancel(cancel_protection: *CancelProtection) void {
            assert(cancel_protection.acknowledged);
            cancel_protection.acknowledged = false;
        }

        test check {
            try std.testing.expectEqual(Io.CancelProtection.unblocked, check(.unblocked));
            try std.testing.expectEqual(Io.CancelProtection.blocked, check(.{
                .user = .unblocked,
                .acknowledged = true,
            }));
            try std.testing.expectEqual(Io.CancelProtection.blocked, check(.{
                .user = .blocked,
                .acknowledged = false,
            }));
            try std.testing.expectEqual(Io.CancelProtection.blocked, check(.{
                .user = .blocked,
                .acknowledged = true,
            }));
        }
    }