fix(cli_eval): add get_app_or_root_agent resolver

Eval flows currently access `agent_module.agent.root_agent` directly,
which drops the wrapping `App` (and therefore its plugins, context-cache
config, and resumability config). Add `get_app_or_root_agent` that
returns the `(app, root_agent)` pair, mirroring the resolution order
`AgentLoader._load_from_module_or_package` already uses on the web /
run paths. Keep `get_root_agent` as a back-compat wrapper.

This commit is the resolver and unit tests only; subsequent commits plumb
the App through `EvaluationGenerator` and `LocalEvalService` so plugins
fire during eval runs.

Author: saifer82

src/google/adk/cli/cli_eval.py

@@ -24,7 +24,9 @@
 import click
 from google.genai import types as genai_types
 
+from ..agents.base_agent import BaseAgent
 from ..agents.llm_agent import Agent
+from ..apps.app import App
 from ..evaluation.base_eval_service import BaseEvalService
 from ..evaluation.base_eval_service import EvaluateConfig
 from ..evaluation.base_eval_service import EvaluateRequest
@@ -86,11 +88,33 @@ def get_default_metric_info(
   )
 
 
-def get_root_agent(agent_module_file_path: str) -> Agent:
-  """Returns root agent given the agent module."""
+def get_app_or_root_agent(
+    agent_module_file_path: str,
+) -> tuple[Optional[App], BaseAgent]:
+  """Returns the (app, root_agent) pair for the given agent module.
+
+  Resolution order mirrors `AgentLoader._load_from_module_or_package`:
+  if the module exposes an `App` instance via `agent.app`, that App and its
+  `root_agent` are returned. Otherwise `app` is None and the bare
+  `agent.root_agent` is returned. This lets eval flows participate in the
+  App's plugin / cache / resumability lifecycle when one is defined, while
+  preserving the bare-`root_agent` path for projects that don't use App.
+  """
   agent_module = _get_agent_module(agent_module_file_path)
-  root_agent = agent_module.agent.root_agent
-  return root_agent
+  app = getattr(agent_module.agent, "app", None)
+  if isinstance(app, App):
+    return app, app.root_agent
+  return None, agent_module.agent.root_agent
+
+
+def get_root_agent(agent_module_file_path: str) -> Agent:
+  """Returns root agent given the agent module.
+
+  Kept for backward compatibility. New callers should prefer
+  `get_app_or_root_agent`, which also surfaces the wrapping `App` (if any)
+  so plugins, context-cache, and resumability configs are honored.
+  """
+  return get_app_or_root_agent(agent_module_file_path)[1]
 
 
 def try_get_reset_func(agent_module_file_path: str) -> Any:

tests/unittests/cli/utils/test_cli_eval.py

@@ -19,6 +19,9 @@
 from types import SimpleNamespace
 from unittest import mock
 
+from google.adk.agents.base_agent import BaseAgent
+from google.adk.apps.app import App
+
 
 def test_get_eval_sets_manager_local(monkeypatch):
   mock_local_manager = mock.MagicMock()
@@ -49,3 +52,62 @@ def test_get_eval_sets_manager_gcs(monkeypatch):
   )
   assert manager == mock_gcs_manager
   mock_create_gcs.assert_called_once_with("gs://bucket")
+
+
+def _patch_agent_module(monkeypatch, agent_namespace):
+  """Patches `_get_agent_module` to return a stub whose `.agent` matches."""
+  monkeypatch.setattr(
+      "google.adk.cli.cli_eval._get_agent_module",
+      lambda _path: SimpleNamespace(agent=agent_namespace),
+  )
+
+
+def test_get_app_or_root_agent_with_app(monkeypatch):
+  """When the module exposes an App, both app and its root_agent are returned."""
+  root_agent = BaseAgent(name="root_agent")
+  app = App(name="my_app", root_agent=root_agent)
+  _patch_agent_module(monkeypatch, SimpleNamespace(root_agent=root_agent, app=app))
+
+  from google.adk.cli.cli_eval import get_app_or_root_agent
+
+  resolved_app, resolved_root = get_app_or_root_agent("some/path")
+  assert resolved_app is app
+  assert resolved_root is root_agent
+
+
+def test_get_app_or_root_agent_without_app(monkeypatch):
+  """When only `root_agent` is exposed, app is None."""
+  root_agent = BaseAgent(name="root_agent")
+  _patch_agent_module(monkeypatch, SimpleNamespace(root_agent=root_agent))
+
+  from google.adk.cli.cli_eval import get_app_or_root_agent
+
+  resolved_app, resolved_root = get_app_or_root_agent("some/path")
+  assert resolved_app is None
+  assert resolved_root is root_agent
+
+
+def test_get_app_or_root_agent_app_attribute_not_an_app_instance(monkeypatch):
+  """If `app` exists but is not an App, it is ignored and we fall back."""
+  root_agent = BaseAgent(name="root_agent")
+  _patch_agent_module(
+      monkeypatch,
+      SimpleNamespace(root_agent=root_agent, app="not-an-app"),
+  )
+
+  from google.adk.cli.cli_eval import get_app_or_root_agent
+
+  resolved_app, resolved_root = get_app_or_root_agent("some/path")
+  assert resolved_app is None
+  assert resolved_root is root_agent
+
+
+def test_get_root_agent_back_compat(monkeypatch):
+  """Existing `get_root_agent` callers keep getting the bare agent back."""
+  root_agent = BaseAgent(name="root_agent")
+  app = App(name="my_app", root_agent=root_agent)
+  _patch_agent_module(monkeypatch, SimpleNamespace(root_agent=root_agent, app=app))
+
+  from google.adk.cli.cli_eval import get_root_agent
+
+  assert get_root_agent("some/path") is root_agent