fix(cli): lazy-import GCS deps so adk web works without google-cloud-storage

The `DevServer` import chain unconditionally imported
`gcs_eval_set_results_manager` and `gcs_eval_sets_manager` at module
level, which require `google-cloud-storage`. This caused `adk web` to
silently fall back to `ApiServer` on a fresh `pip install google-adk`,
leaving the dev UI unreachable.

Fix: move GCS imports behind `TYPE_CHECKING` for type annotations and
lazy-import inside `create_gcs_eval_managers_from_uri()` where they are
actually needed. Also add `python-multipart` to core dependencies since
it is required for Builder UI endpoints in `adk web`.

Fixes #5787

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mangod12

pyproject.toml

@@ -47,6 +47,7 @@ dependencies = [
   "packaging>=21",
   "pydantic>=2.12,<3",
   "python-dotenv>=1,<2",
+  "python-multipart>=0.0.9",
   # go/keep-sorted start
   "pyyaml>=6.0.2,<7",
   "requests>=2.32.4,<3",

src/google/adk/cli/utils/evals.py

@@ -15,17 +15,20 @@
 from __future__ import annotations
 
 import os
+from typing import TYPE_CHECKING
 
 from pydantic import alias_generators
 from pydantic import BaseModel
 from pydantic import ConfigDict
 
 from ...evaluation.eval_case import Invocation
 from ...evaluation.evaluation_generator import EvaluationGenerator
-from ...evaluation.gcs_eval_set_results_manager import GcsEvalSetResultsManager
-from ...evaluation.gcs_eval_sets_manager import GcsEvalSetsManager
 from ...sessions.session import Session
 
+if TYPE_CHECKING:
+  from ...evaluation.gcs_eval_set_results_manager import GcsEvalSetResultsManager
+  from ...evaluation.gcs_eval_sets_manager import GcsEvalSetsManager
+
 
 class GcsEvalManagers(BaseModel):
   model_config = ConfigDict(
@@ -68,6 +71,9 @@ def create_gcs_eval_managers_from_uri(
       ValueError: If the eval_storage_uri is not supported.
   """
   if eval_storage_uri.startswith('gs://'):
+    from ...evaluation.gcs_eval_set_results_manager import GcsEvalSetResultsManager
+    from ...evaluation.gcs_eval_sets_manager import GcsEvalSetsManager
+
     gcs_bucket = eval_storage_uri.split('://')[1]
     eval_sets_manager = GcsEvalSetsManager(
         bucket_name=gcs_bucket, project=os.environ['GOOGLE_CLOUD_PROJECT']

tests/unittests/cli/utils/test_evals.py

@@ -25,11 +25,11 @@
 
 @mock.patch.dict(os.environ, {'GOOGLE_CLOUD_PROJECT': 'test-project'})
 @mock.patch(
-    'google.adk.cli.utils.evals.GcsEvalSetResultsManager',
+    'google.adk.evaluation.gcs_eval_set_results_manager.GcsEvalSetResultsManager',
     autospec=True,
 )
 @mock.patch(
-    'google.adk.cli.utils.evals.GcsEvalSetsManager',
+    'google.adk.evaluation.gcs_eval_sets_manager.GcsEvalSetsManager',
     autospec=True,
 )
 def test_create_gcs_eval_managers_from_uri_success(
@@ -61,3 +61,15 @@ def test_create_gcs_eval_managers_from_uri_success(
 def test_create_gcs_eval_managers_from_uri_failure():
   with pytest.raises(ValueError):
     evals.create_gcs_eval_managers_from_uri('unsupported-uri')
+
+
+def test_evals_module_does_not_import_gcs_at_module_level():
+  """GCS classes should be lazy-imported, not at module level."""
+  import inspect
+
+  source = inspect.getsource(evals)
+  # The top-level imports should not contain direct GCS imports
+  # (they should be behind TYPE_CHECKING or inside functions)
+  module_globals = vars(evals)
+  assert 'GcsEvalSetResultsManager' not in module_globals
+  assert 'GcsEvalSetsManager' not in module_globals