Add default remote keys for all feature flags

[bjtitus]

Description

Any feature flag we add currently needs a corresponding remoteKey added.

We shouldn't need to do this since any flag should be overridable server side for flexibility.

Step-by-step reproduction instructions

1. Add a Feature Flag to FeatureFlag.swift
2. Add an overwritten value to Firebase Remote Config
3. New value should replace the client-side value

Screenshots or screen recording

No response

Did you search for existing bug reports?

• I have searched for existing bug reports.

Device, Operating system, and Pocket Casts app version

No response

[leandroalonso]

@bjtitus I think there's one additional test we should do:

1. Add a Feature Flag to FeatureFlag.swift
2. Add an overwritten value to Firebase Remote Config
3. New value should replace the client-side value
4. Delete the Firebase Remote Config one
5. ✅ Local feature flag value should remain the same (we don't want flags to change values when we delete them)

[bjtitus]

✅ Local feature flag value should remain the same

Are you saying we should store the changed Remote Config value instead of reverting to the value in FeatureFlag.default?

Is the idea to cover future flag removal?

I fear this could make it much hard for us to debug issues without knowing which flag values a user should have. As an example, if someone accidentally added a flag and then deleted it, would we be able to determine which value a user should have on their device without needing to fetch logs/data directly from them?

If we do decide to do this, I think it should be done separately from the default values since this would be new functionality on top of just adding a default value for each flag.

[leandroalonso]

Is the idea to cover future flag removal?

Yes!

My main reasoning is: that if an app is working with a flag set to a certain value, it should not change. Think about this scenario:

1. The flag test has a default value of true
2. We configured this flag to be false for versions below 7.60
3. After some time, we delete flag test
4. Now, for versions below 7.60 the flag will change to true

I fear this could make it much hard for us to debug issues without knowing which flag values a user should have. As an example, if someone accidentally added a flag and then deleted it, would we be able to determine which value a user should have on their device without needing to fetch logs/data directly from them?

I agree with you but overall in support requests one of the things we always recommend is to be on the latest version — but I also agree that this is an argument that goes both ways.

If we do decide to do this, I think it should be done separately from the default values since this would be new functionality on top of just adding a default value for each flag.

In terms of implementation wouldn't that be just a matter of settings flags values only from the list that is returned from the backend? So in case test flag is not there anymore, we do nothing with it.

[bjtitus]

In terms of implementation wouldn't that be just a matter of settings flags values only from the list that is returned from the backend?

Yeah, the implementation isn't too bad, I just wanted to make sure it's easily revertible if we end up with issues. I think having a separate commit is fine: 0f4659e