refactor(runtime): consolidate Relay lifecycle ownership

Signed-off-by: Alex Fournier <afournier@nvidia.com>

hermes_cli/plugins.py

@@ -2047,32 +2047,10 @@ def discover_plugins(force: bool = False) -> None:
 
 
 def invoke_hook(hook_name: str, **kwargs: Any) -> List[Any]:
-    """Invoke a lifecycle hook on built-in observers and loaded plugins.
+    """Invoke a lifecycle hook on loaded plugins.
 
     Returns a list of non-``None`` return values from plugin callbacks.
     """
-    if hook_name == "on_session_start":
-        try:
-            from hermes_cli.observability import prepare_lifecycle
-
-            prepare_lifecycle(hook_name, **kwargs)
-        except Exception:
-            logger.warning("Built-in observability preparation failed", exc_info=True)
-        results = get_plugin_manager().invoke_hook(hook_name, **kwargs)
-        try:
-            from hermes_cli.observability import observe_lifecycle
-
-            observe_lifecycle(hook_name, **kwargs)
-        except Exception:
-            logger.warning("Built-in observability hook failed", exc_info=True)
-        return results
-
-    try:
-        from hermes_cli.observability import observe_lifecycle
-
-        observe_lifecycle(hook_name, **kwargs)
-    except Exception:
-        logger.warning("Built-in observability hook failed", exc_info=True)
     return get_plugin_manager().invoke_hook(hook_name, **kwargs)
 
 
@@ -2094,14 +2072,7 @@ def has_middleware(kind: str) -> bool:
 
 
 def has_hook(hook_name: str) -> bool:
-    """Return True when a built-in observer or plugin handles a hook."""
-    try:
-        from hermes_cli.observability import handles_hook
-
-        if handles_hook(hook_name):
-            return True
-    except Exception:
-        logger.warning("Unable to inspect built-in shared-metrics hooks", exc_info=True)
+    """Return True when a loaded plugin handles a hook."""
     return get_plugin_manager().has_hook(hook_name)