chore: add deprecation warnings for grpcio

packages/gapic-generator/gapic/templates/%namespace/%name_%version/%sub/__init__.py.j2

@@ -63,6 +63,23 @@ from .types.{{ proto.module_name }} import {{ enum.name }}
 api_core.check_python_version("{{package_path}}")
 api_core.check_dependency_versions("{{package_path}}")
 
+_PQC_GRPC_WARNING_TEMPLATE = (
+    "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+    "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+    "Support for non-PQC environments is deprecated. In October 2026, "
+    "Google Cloud Python client libraries will raise their minimum requirements "
+    "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+    "For more details on Google Cloud's post-quantum security migration, visit: "
+    "https://cloud.google.com/security/resources/post-quantum-cryptography"
+)
+
+api_core.warn_deprecation_for_versions_less_than(
+    "{{package_path}}",
+    "grpcio",
+    "1.83.0",
+    message_template=_PQC_GRPC_WARNING_TEMPLATE,
+)
+
 {#  Define __all__.
     This requires the full set of imported names, so we iterate over
     them again.

packages/gapic-generator/tests/integration/goldens/asset/google/cloud/asset_v1/__init__.py

@@ -121,6 +121,30 @@
 api_core.check_python_version("google.cloud.asset_v1")
 api_core.check_dependency_versions("google.cloud.asset_v1")
 
+try:
+    from google.api_core._python_package_support import (
+        warn_deprecation_for_versions_less_than,
+    )
+
+    _PQC_GRPC_WARNING_TEMPLATE = (
+        "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+        "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+        "Support for non-PQC environments is deprecated. In October 2026, "
+        "Google Cloud Python client libraries will raise their minimum requirements "
+        "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+        "For more details on Google Cloud's post-quantum security migration, visit: "
+        "https://cloud.google.com/security/resources/post-quantum-cryptography"
+    )
+
+    warn_deprecation_for_versions_less_than(
+        "google.cloud.asset_v1",
+        "grpcio",
+        "1.83.0",
+        message_template=_PQC_GRPC_WARNING_TEMPLATE,
+    )
+except Exception:
+    pass
+
 __all__ = (
     'AssetServiceAsyncClient',
 'AnalyzeIamPolicyLongrunningMetadata',

packages/gapic-generator/tests/integration/goldens/credentials/google/iam/credentials_v1/__init__.py

@@ -47,6 +47,30 @@
 api_core.check_python_version("google.iam.credentials_v1")
 api_core.check_dependency_versions("google.iam.credentials_v1")
 
+try:
+    from google.api_core._python_package_support import (
+        warn_deprecation_for_versions_less_than,
+    )
+
+    _PQC_GRPC_WARNING_TEMPLATE = (
+        "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+        "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+        "Support for non-PQC environments is deprecated. In October 2026, "
+        "Google Cloud Python client libraries will raise their minimum requirements "
+        "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+        "For more details on Google Cloud's post-quantum security migration, visit: "
+        "https://cloud.google.com/security/resources/post-quantum-cryptography"
+    )
+
+    warn_deprecation_for_versions_less_than(
+        "google.iam.credentials_v1",
+        "grpcio",
+        "1.83.0",
+        message_template=_PQC_GRPC_WARNING_TEMPLATE,
+    )
+except Exception:
+    pass
+
 __all__ = (
     'IAMCredentialsAsyncClient',
 'GenerateAccessTokenRequest',

packages/gapic-generator/tests/integration/goldens/eventarc/google/cloud/eventarc_v1/__init__.py

@@ -119,6 +119,30 @@
 api_core.check_python_version("google.cloud.eventarc_v1")
 api_core.check_dependency_versions("google.cloud.eventarc_v1")
 
+try:
+    from google.api_core._python_package_support import (
+        warn_deprecation_for_versions_less_than,
+    )
+
+    _PQC_GRPC_WARNING_TEMPLATE = (
+        "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+        "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+        "Support for non-PQC environments is deprecated. In October 2026, "
+        "Google Cloud Python client libraries will raise their minimum requirements "
+        "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+        "For more details on Google Cloud's post-quantum security migration, visit: "
+        "https://cloud.google.com/security/resources/post-quantum-cryptography"
+    )
+
+    warn_deprecation_for_versions_less_than(
+        "google.cloud.eventarc_v1",
+        "grpcio",
+        "1.83.0",
+        message_template=_PQC_GRPC_WARNING_TEMPLATE,
+    )
+except Exception:
+    pass
+
 __all__ = (
     'EventarcAsyncClient',
 'Channel',

packages/gapic-generator/tests/integration/goldens/logging/google/cloud/logging_v2/__init__.py

@@ -123,6 +123,30 @@
 api_core.check_python_version("google.cloud.logging_v2")
 api_core.check_dependency_versions("google.cloud.logging_v2")
 
+try:
+    from google.api_core._python_package_support import (
+        warn_deprecation_for_versions_less_than,
+    )
+
+    _PQC_GRPC_WARNING_TEMPLATE = (
+        "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+        "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+        "Support for non-PQC environments is deprecated. In October 2026, "
+        "Google Cloud Python client libraries will raise their minimum requirements "
+        "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+        "For more details on Google Cloud's post-quantum security migration, visit: "
+        "https://cloud.google.com/security/resources/post-quantum-cryptography"
+    )
+
+    warn_deprecation_for_versions_less_than(
+        "google.cloud.logging_v2",
+        "grpcio",
+        "1.83.0",
+        message_template=_PQC_GRPC_WARNING_TEMPLATE,
+    )
+except Exception:
+    pass
+
 __all__ = (
     'ConfigServiceV2AsyncClient',
     'LoggingServiceV2AsyncClient',

packages/gapic-generator/tests/integration/goldens/logging_internal/google/cloud/logging_v2/__init__.py

@@ -123,6 +123,30 @@
 api_core.check_python_version("google.cloud.logging_v2")
 api_core.check_dependency_versions("google.cloud.logging_v2")
 
+try:
+    from google.api_core._python_package_support import (
+        warn_deprecation_for_versions_less_than,
+    )
+
+    _PQC_GRPC_WARNING_TEMPLATE = (
+        "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+        "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+        "Support for non-PQC environments is deprecated. In October 2026, "
+        "Google Cloud Python client libraries will raise their minimum requirements "
+        "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+        "For more details on Google Cloud's post-quantum security migration, visit: "
+        "https://cloud.google.com/security/resources/post-quantum-cryptography"
+    )
+
+    warn_deprecation_for_versions_less_than(
+        "google.cloud.logging_v2",
+        "grpcio",
+        "1.83.0",
+        message_template=_PQC_GRPC_WARNING_TEMPLATE,
+    )
+except Exception:
+    pass
+
 __all__ = (
     'BaseConfigServiceV2AsyncClient',
     'BaseMetricsServiceV2AsyncClient',

packages/gapic-generator/tests/integration/goldens/redis/google/cloud/redis_v1/__init__.py

@@ -65,6 +65,30 @@
 api_core.check_python_version("google.cloud.redis_v1")
 api_core.check_dependency_versions("google.cloud.redis_v1")
 
+try:
+    from google.api_core._python_package_support import (
+        warn_deprecation_for_versions_less_than,
+    )
+
+    _PQC_GRPC_WARNING_TEMPLATE = (
+        "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+        "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+        "Support for non-PQC environments is deprecated. In October 2026, "
+        "Google Cloud Python client libraries will raise their minimum requirements "
+        "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+        "For more details on Google Cloud's post-quantum security migration, visit: "
+        "https://cloud.google.com/security/resources/post-quantum-cryptography"
+    )
+
+    warn_deprecation_for_versions_less_than(
+        "google.cloud.redis_v1",
+        "grpcio",
+        "1.83.0",
+        message_template=_PQC_GRPC_WARNING_TEMPLATE,
+    )
+except Exception:
+    pass
+
 __all__ = (
     'CloudRedisAsyncClient',
 'CloudRedisClient',

packages/gapic-generator/tests/integration/goldens/redis_selective/google/cloud/redis_v1/__init__.py

@@ -58,6 +58,30 @@
 api_core.check_python_version("google.cloud.redis_v1")
 api_core.check_dependency_versions("google.cloud.redis_v1")
 
+try:
+    from google.api_core._python_package_support import (
+        warn_deprecation_for_versions_less_than,
+    )
+
+    _PQC_GRPC_WARNING_TEMPLATE = (
+        "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+        "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+        "Support for non-PQC environments is deprecated. In October 2026, "
+        "Google Cloud Python client libraries will raise their minimum requirements "
+        "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+        "For more details on Google Cloud's post-quantum security migration, visit: "
+        "https://cloud.google.com/security/resources/post-quantum-cryptography"
+    )
+
+    warn_deprecation_for_versions_less_than(
+        "google.cloud.redis_v1",
+        "grpcio",
+        "1.83.0",
+        message_template=_PQC_GRPC_WARNING_TEMPLATE,
+    )
+except Exception:
+    pass
+
 __all__ = (
     'CloudRedisAsyncClient',
 'CloudRedisClient',

packages/gapic-generator/tests/integration/goldens/storagebatchoperations/google/cloud/storagebatchoperations_v1/__init__.py

@@ -67,6 +67,30 @@
 api_core.check_python_version("google.cloud.storagebatchoperations_v1")
 api_core.check_dependency_versions("google.cloud.storagebatchoperations_v1")
 
+try:
+    from google.api_core._python_package_support import (
+        warn_deprecation_for_versions_less_than,
+    )
+
+    _PQC_GRPC_WARNING_TEMPLATE = (
+        "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+        "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+        "Support for non-PQC environments is deprecated. In October 2026, "
+        "Google Cloud Python client libraries will raise their minimum requirements "
+        "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+        "For more details on Google Cloud's post-quantum security migration, visit: "
+        "https://cloud.google.com/security/resources/post-quantum-cryptography"
+    )
+
+    warn_deprecation_for_versions_less_than(
+        "google.cloud.storagebatchoperations_v1",
+        "grpcio",
+        "1.83.0",
+        message_template=_PQC_GRPC_WARNING_TEMPLATE,
+    )
+except Exception:
+    pass
+
 __all__ = (
     'StorageBatchOperationsAsyncClient',
 'BucketList',

packages/google-api-core/google/api_core/_python_package_support.py

@@ -30,14 +30,37 @@
 # about deprecated and unsupported versions.
 DependencyConstraint = namedtuple(
     "DependencyConstraint",
-    ["package_name", "minimum_fully_supported_version", "recommended_version"],
+    [
+        "package_name",
+        "minimum_fully_supported_version",
+        "recommended_version",
+        "message_template",
+    ],
+    defaults=(None, None),
 )
+
+PQC_GRPC_WARNING_TEMPLATE = (
+    "Package {consumer_package} depends on {dependency_package}, currently installed at version {version_used_string}. "
+    "grpcio < 1.83.0 does not support Post-Quantum Cryptography (PQC). "
+    "Support for non-PQC environments is deprecated. In October 2026, "
+    "Google Cloud Python packages will raise their minimum requirements "
+    "(including google-api-core, grpcio, and grpcio-status) to enforce grpcio >= 1.83.0. "
+    "For more details on Google Cloud's post-quantum security migration, visit: "
+    "https://cloud.google.com/security/resources/post-quantum-cryptography"
+)
+
 _PACKAGE_DEPENDENCY_WARNINGS = [
     DependencyConstraint(
         "google.protobuf",
         minimum_fully_supported_version="6.33.5",
         recommended_version="6.x",
-    )
+    ),
+    DependencyConstraint(
+        "grpcio",
+        minimum_fully_supported_version="1.83.0",
+        recommended_version="1.83.x",
+        message_template=PQC_GRPC_WARNING_TEMPLATE,
+    ),
 ]
 
 
@@ -162,7 +185,7 @@ def warn_deprecation_for_versions_less_than(
         ) = _get_distribution_and_import_packages(consumer_import_package)
 
         recommendation = (
-            " (we recommend {recommended_version})" if recommended_version else ""
+            f" (we recommend {recommended_version})" if recommended_version else ""
         )
         message_template = message_template or _flatten_message(
             """
@@ -222,4 +245,5 @@ def check_dependency_versions(
             package_info.package_name,
             package_info.minimum_fully_supported_version,
             recommended_version=package_info.recommended_version,
+            message_template=package_info.message_template,
         )

packages/google-api-core/tests/unit/test_python_package_support.py

@@ -18,6 +18,7 @@
 import pytest
 
 from google.api_core._python_package_support import (
+    PQC_GRPC_WARNING_TEMPLATE,
     DependencyConstraint,
     DependencyVersion,
     check_dependency_versions,
@@ -37,11 +38,10 @@ def test_get_dependency_version(mocker, version_string_to_test):
         parse_version_to_tuple(version_string_to_test), version_string_to_test
     )
     assert get_dependency_version("some-package") == expected
-
     mock_importlib.assert_called_once_with("some-package")
 
     # Test package not found
-    mock_importlib.side_effect = ImportError
+    mock_importlib.side_effect = Exception
     assert get_dependency_version("not-a-package") == DependencyVersion(None, "--")
 
 
@@ -125,8 +125,40 @@ def test_check_dependency_versions_with_custom_warnings(mock_warn):
 
     assert mock_warn.call_count == 2
     mock_warn.assert_any_call(
-        "my-consumer", "pkg1", "1.0.0", recommended_version="2.0.0"
+        "my-consumer",
+        "pkg1",
+        "1.0.0",
+        recommended_version="2.0.0",
+        message_template=None,
+    )
+    mock_warn.assert_any_call(
+        "my-consumer",
+        "pkg2",
+        "2.0.0",
+        recommended_version="3.0.0",
+        message_template=None,
+    )
+
+
+@patch(
+    "google.api_core._python_package_support.warn_deprecation_for_versions_less_than"
+)
+def test_check_dependency_versions_default(mock_warn):
+    """Test check_dependency_versions with default package dependency warnings."""
+    check_dependency_versions("my-consumer")
+
+    assert mock_warn.call_count == 2
+    mock_warn.assert_any_call(
+        "my-consumer",
+        "google.protobuf",
+        "6.33.5",
+        recommended_version="6.x",
+        message_template=None,
     )
     mock_warn.assert_any_call(
-        "my-consumer", "pkg2", "2.0.0", recommended_version="3.0.0"
+        "my-consumer",
+        "grpcio",
+        "1.83.0",
+        recommended_version="1.83.x",
+        message_template=PQC_GRPC_WARNING_TEMPLATE,
     )