Outcome of resolving the realtime model for a session: either a usable RealtimeModelResolution
or a specific, human-readable failure reason (used for explicit preferred-model failures, where the
generic "no model" message would hide WHY the user's chosen model couldn't be used).
Outcome of resolving the realtime model for a session: either a usable RealtimeModelResolution or a specific, human-readable failure reason (used for explicit preferred-model failures, where the generic "no model" message would hide WHY the user's chosen model couldn't be used).