docs: Spec putContext / track(ConfidenceContextProducer)

[fabriziodemaria]

Observation 1

From the DemoApp:

@StateObject private var lifecycleObserver: ConfidenceContextProducer = ConfidenceAppLifecycleProducer()
...
let confidence = Confidence.Builder(...).build()
confidence.track(producer: lifecycleObserver) // triggers fetchAndActivate
...
try await confidence.fetchAndActivate() // the app calls fetchAndActivate

The ideal situation would be to have a single fetchAndActivate call, and the ability to await an async function to make sure the flags are fresh and ready in the cache. However, our current API portfolio doesn't seem to allow for both of those things together.

Observation 2

Code snippet here.

Today it's impossible to have a setup where the context is changed and the UI showing a loading indicator until the resolve is complete, while at the same time having a single fetchAndActivate call for each context change.

Possible improvements

• Confidence builder accept a list of ContextProducers, and applies the context from them for the first time without calling fetchAndActivate
• putContext is made async: users can wait for the new flags to be ready before reading values (this is probably harder to achieve with the ContextProducer solution)

[fabriziodemaria]

Here, I would add the following to the Spec:

putContext is an await-able function, which returns when the flag cache is ready and reflects the newly configured context. When using ConfidenceContextProducer, the context can change more dynamically and stale value are to be expected.