I am trying redux right now and very excited about ideas behind it, but first real task ruined the whole thing.
In Redux we should store immutable state and produce some reducers to transform it. It means that every state could be reproduced by given previous state and a list of actions fired.
But what if I need to store third-party/legacy stateful object? For example it may be something like gallery or websocket client. I assume that I'm able to use reducers to start/stop/manage it somehow, but the state I have no longer stateless and it not guaranteed to be repeatable with given list of reducers (websocket client may generate new session id or even be unable to maintain connection).
What is convenient way to solve these issues?
As I see this, your problem boils down to: How do you mix Redux with stateful components (legacy/third party)?
You are right, Redux is better suited for controlled components, that is, components that are mostly stateless and are supposed to receive everything as props. Just keep in mind that having some state doesn't necessarily make the component unusable in Redux. Example: For an Autocomplete component, the "open" state (whether or not the dropdown is visible) doesn't necessarily has to be controlled by Redux. So, depending on the how the component is implemented, you're definitely having a hard time integrating it into Redux, or maybe not.
You have 2 options: You either refactor the problematic components so they're now controlled, or you don't keep their state on Redux (you're not required to). The answer will vary depending on the circumstances. There's not a globally accepted solution for your case, that I know of.