Static ReadonlyFALLBACK_Last-resort fallback agent name (step 4). Kept as a constant rather than another setting so the system has a hard floor even if metadata sync has never run on a fresh install — preserves today's "Sage is the default" behavior unconditionally.
Static ReadonlySETTING_Application Setting key consulted in steps 2 and 3.
Resolve the default agent for this turn. Walks the 4-step chain; throws a descriptive
error if every step misses (vs. the previous code path's silent null return, which
made misconfigurations hard to spot at the call site).
Resolves the default agent for a conversation turn.
Usually accessed via
ConversationsRuntime.Instance.DefaultAgent. Stateless beyond lazy delegation toApplicationSettingEngineandAIEngineBase.