Variable storageLayerSchema`Const`

storageLayerSchema: ZodObject<
    {
        path: ZodString;
        visibility: ZodOptional<
            ZodEnum<{ exported: "exported"; private: "private" }>,
        >;
        writable: ZodOptional<ZodBoolean>;
    },
    $strip,
> = ...

One storage layer (§5a). Layers stack bottom → top; default read-only, exported.