Investigate environment detection in our overall environment UX to see if there are scenarios where discovery is unnecessary

[karrtikr]

Related: #17498 #18647 #18671

Users can use the API or the refresh icon for triggering it if needed:

Check #19102 (comment) for investigation results.

[karrtikr]

Auto-triggering discovery is probably not needed. Only a couple places need it:

• When auto-selecting interpreters for a new workspace.
• Triggering it for every scope exactly once (across sessions).

[karrtikr]

Question: Is triggering it once in the first session even needed, if an interpreter is already selected?

Perhaps not from a user perspective (#18647), but yes, the discovery API is only considered to be ready for query once refresh has been triggered.

Reasons for doing it in the first session:

• Jupyter is going to do that anyways via the API to fetch kernels.
• Internally it is assumed discovery is triggered atleast once, changing which might not be worth it for now. For example, Auto-selection (which triggers discovery) is always triggered even if an interpreter is explicitly selected, so that user has an auto-selected interpreter to fallback on if the selected interpreter is cleared. Another example: Investigate environment detection in our overall environment UX to see if there are scenarios where discovery is unnecessary #19102 (comment)
• Select Interpreter section in the getting started section already has environments populated.
• Rest of sessions should be good.

[karrtikr]

We also need to make sure legacy jupyter integration APIs still work.

[karrtikr]

Proposed approach, only auto-trigger discovery if:

• A user attempts to choose a different interpreter
• When a particular scope (workspace or global) is opened for the first time
• When jupyter queries legacy discovery APIs for envs (Jupyter currently queries this on startup)
• Environment cache is empty

Note we also need to make sure that the selected environment has the latest version, now that discovery isn't run by default.