diff --git a/.flake8 b/.flake8
index 32986c792..90316de21 100644
--- a/.flake8
+++ b/.flake8
@@ -1,28 +1,29 @@
 # -*- coding: utf-8 -*-
-#
-# Copyright 2024 Google LLC
+# Copyright 2025 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
-#     https://www.apache.org/licenses/LICENSE-2.0
+#     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-# Generated by synthtool. DO NOT EDIT!
+#
 [flake8]
+# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333):
+# Resolve flake8 lint issues
 ignore = E203, E231, E266, E501, W503
 exclude =
-  # Exclude generated code.
-  **/proto/**
+  # TODO(https://github.com/googleapis/gapic-generator-python/issues/2333):
+  # Ensure that generated code passes flake8 lint
   **/gapic/**
   **/services/**
   **/types/**
+  # Exclude Protobuf gencode
   *_pb2.py
 
   # Standard linting exemptions.
diff --git a/MANIFEST.in b/MANIFEST.in
index d6814cd60..dae249ec8 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,25 +1,20 @@
 # -*- coding: utf-8 -*-
-#
-# Copyright 2024 Google LLC
+# Copyright 2025 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
-#     https://www.apache.org/licenses/LICENSE-2.0
+#     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-# Generated by synthtool. DO NOT EDIT!
+#
 include README.rst LICENSE
-recursive-include google *.json *.proto py.typed
+recursive-include google *.py *.pyi *.json *.proto py.typed
 recursive-include tests *
 global-exclude *.py[co]
 global-exclude __pycache__
-
-# Exclude scripts for samples readmegen
-prune scripts/readme-gen
diff --git a/google/pubsub_v1/services/publisher/async_client.py b/google/pubsub_v1/services/publisher/async_client.py
index 87838c006..52f1f1e30 100644
--- a/google/pubsub_v1/services/publisher/async_client.py
+++ b/google/pubsub_v1/services/publisher/async_client.py
@@ -37,6 +37,7 @@
 from google.api_core import retry_async as retries
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 
 try:
@@ -1662,5 +1663,8 @@ async def __aexit__(self, exc_type, exc, tb):
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 __all__ = ("PublisherAsyncClient",)
diff --git a/google/pubsub_v1/services/publisher/client.py b/google/pubsub_v1/services/publisher/client.py
index c94cec688..c8f39273e 100644
--- a/google/pubsub_v1/services/publisher/client.py
+++ b/google/pubsub_v1/services/publisher/client.py
@@ -47,6 +47,7 @@
 from google.auth.transport.grpc import SslCredentials  # type: ignore
 from google.auth.exceptions import MutualTLSChannelError  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 try:
     OptionalRetry = Union[retries.Retry, gapic_v1.method._MethodDefault, None]
@@ -2129,5 +2130,7 @@ def test_iam_permissions(
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
 
 __all__ = ("PublisherClient",)
diff --git a/google/pubsub_v1/services/publisher/transports/base.py b/google/pubsub_v1/services/publisher/transports/base.py
index 354a6c714..0fb41c922 100644
--- a/google/pubsub_v1/services/publisher/transports/base.py
+++ b/google/pubsub_v1/services/publisher/transports/base.py
@@ -25,6 +25,7 @@
 from google.api_core import retry as retries
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 from google.iam.v1 import iam_policy_pb2  # type: ignore
 from google.iam.v1 import policy_pb2  # type: ignore
@@ -35,6 +36,9 @@
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 class PublisherTransport(abc.ABC):
     """Abstract transport class for Publisher."""
diff --git a/google/pubsub_v1/services/publisher/transports/grpc.py b/google/pubsub_v1/services/publisher/transports/grpc.py
index f27b968a8..9e8ed1737 100644
--- a/google/pubsub_v1/services/publisher/transports/grpc.py
+++ b/google/pubsub_v1/services/publisher/transports/grpc.py
@@ -73,12 +73,11 @@ def intercept_unary_unary(self, continuation, client_call_details, request):
                 f"Sending request for {client_call_details.method}",
                 extra={
                     "serviceName": "google.pubsub.v1.Publisher",
-                    "rpcName": client_call_details.method,
+                    "rpcName": str(client_call_details.method),
                     "request": grpc_request,
                     "metadata": grpc_request["metadata"],
                 },
             )
-
         response = continuation(client_call_details, request)
         if logging_enabled:  # pragma: NO COVER
             response_metadata = response.trailing_metadata()
diff --git a/google/pubsub_v1/services/publisher/transports/rest.py b/google/pubsub_v1/services/publisher/transports/rest.py
index a5c99da1b..92ee46e15 100644
--- a/google/pubsub_v1/services/publisher/transports/rest.py
+++ b/google/pubsub_v1/services/publisher/transports/rest.py
@@ -23,6 +23,7 @@
 from google.api_core import rest_helpers
 from google.api_core import rest_streaming
 from google.api_core import gapic_v1
+import google.protobuf
 
 from google.protobuf import json_format
 from google.iam.v1 import iam_policy_pb2  # type: ignore
@@ -61,6 +62,9 @@
     rest_version=f"requests@{requests_version}",
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 class PublisherRestInterceptor:
     """Interceptor for Publisher.
diff --git a/google/pubsub_v1/services/schema_service/async_client.py b/google/pubsub_v1/services/schema_service/async_client.py
index 4ebf3ac94..b2d139fa0 100644
--- a/google/pubsub_v1/services/schema_service/async_client.py
+++ b/google/pubsub_v1/services/schema_service/async_client.py
@@ -37,6 +37,7 @@
 from google.api_core import retry_async as retries
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 
 try:
@@ -1775,5 +1776,8 @@ async def __aexit__(self, exc_type, exc, tb):
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 __all__ = ("SchemaServiceAsyncClient",)
diff --git a/google/pubsub_v1/services/schema_service/client.py b/google/pubsub_v1/services/schema_service/client.py
index 40fc381b8..493ffd2b6 100644
--- a/google/pubsub_v1/services/schema_service/client.py
+++ b/google/pubsub_v1/services/schema_service/client.py
@@ -46,6 +46,7 @@
 from google.auth.transport.grpc import SslCredentials  # type: ignore
 from google.auth.exceptions import MutualTLSChannelError  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 try:
     OptionalRetry = Union[retries.Retry, gapic_v1.method._MethodDefault, None]
@@ -2190,5 +2191,7 @@ def test_iam_permissions(
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
 
 __all__ = ("SchemaServiceClient",)
diff --git a/google/pubsub_v1/services/schema_service/transports/base.py b/google/pubsub_v1/services/schema_service/transports/base.py
index c1187d1cd..c30773b74 100644
--- a/google/pubsub_v1/services/schema_service/transports/base.py
+++ b/google/pubsub_v1/services/schema_service/transports/base.py
@@ -25,6 +25,7 @@
 from google.api_core import retry as retries
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 from google.iam.v1 import iam_policy_pb2  # type: ignore
 from google.iam.v1 import policy_pb2  # type: ignore
@@ -36,6 +37,9 @@
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 class SchemaServiceTransport(abc.ABC):
     """Abstract transport class for SchemaService."""
diff --git a/google/pubsub_v1/services/schema_service/transports/grpc.py b/google/pubsub_v1/services/schema_service/transports/grpc.py
index f089c2724..1a746ef43 100644
--- a/google/pubsub_v1/services/schema_service/transports/grpc.py
+++ b/google/pubsub_v1/services/schema_service/transports/grpc.py
@@ -74,12 +74,11 @@ def intercept_unary_unary(self, continuation, client_call_details, request):
                 f"Sending request for {client_call_details.method}",
                 extra={
                     "serviceName": "google.pubsub.v1.SchemaService",
-                    "rpcName": client_call_details.method,
+                    "rpcName": str(client_call_details.method),
                     "request": grpc_request,
                     "metadata": grpc_request["metadata"],
                 },
             )
-
         response = continuation(client_call_details, request)
         if logging_enabled:  # pragma: NO COVER
             response_metadata = response.trailing_metadata()
diff --git a/google/pubsub_v1/services/schema_service/transports/rest.py b/google/pubsub_v1/services/schema_service/transports/rest.py
index f4eab1dd8..6d8902c5d 100644
--- a/google/pubsub_v1/services/schema_service/transports/rest.py
+++ b/google/pubsub_v1/services/schema_service/transports/rest.py
@@ -23,6 +23,7 @@
 from google.api_core import rest_helpers
 from google.api_core import rest_streaming
 from google.api_core import gapic_v1
+import google.protobuf
 
 from google.protobuf import json_format
 from google.iam.v1 import iam_policy_pb2  # type: ignore
@@ -62,6 +63,9 @@
     rest_version=f"requests@{requests_version}",
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 class SchemaServiceRestInterceptor:
     """Interceptor for SchemaService.
diff --git a/google/pubsub_v1/services/subscriber/async_client.py b/google/pubsub_v1/services/subscriber/async_client.py
index 4ad7306f2..5d3dd3da7 100644
--- a/google/pubsub_v1/services/subscriber/async_client.py
+++ b/google/pubsub_v1/services/subscriber/async_client.py
@@ -41,6 +41,7 @@
 from google.api_core import retry_async as retries
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 
 try:
@@ -2635,5 +2636,8 @@ async def __aexit__(self, exc_type, exc, tb):
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 __all__ = ("SubscriberAsyncClient",)
diff --git a/google/pubsub_v1/services/subscriber/client.py b/google/pubsub_v1/services/subscriber/client.py
index 44f3b1598..eef3ab77d 100644
--- a/google/pubsub_v1/services/subscriber/client.py
+++ b/google/pubsub_v1/services/subscriber/client.py
@@ -49,6 +49,7 @@
 from google.auth.transport.grpc import SslCredentials  # type: ignore
 from google.auth.exceptions import MutualTLSChannelError  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 try:
     OptionalRetry = Union[retries.Retry, gapic_v1.method._MethodDefault, None]
@@ -3087,5 +3088,7 @@ def test_iam_permissions(
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
 
 __all__ = ("SubscriberClient",)
diff --git a/google/pubsub_v1/services/subscriber/transports/base.py b/google/pubsub_v1/services/subscriber/transports/base.py
index 01fd7ddcb..cc62113f9 100644
--- a/google/pubsub_v1/services/subscriber/transports/base.py
+++ b/google/pubsub_v1/services/subscriber/transports/base.py
@@ -25,6 +25,7 @@
 from google.api_core import retry as retries
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.oauth2 import service_account  # type: ignore
+import google.protobuf
 
 from google.iam.v1 import iam_policy_pb2  # type: ignore
 from google.iam.v1 import policy_pb2  # type: ignore
@@ -35,6 +36,9 @@
     client_library_version=package_version.__version__
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 class SubscriberTransport(abc.ABC):
     """Abstract transport class for Subscriber."""
diff --git a/google/pubsub_v1/services/subscriber/transports/grpc.py b/google/pubsub_v1/services/subscriber/transports/grpc.py
index 6a10424fe..ec400da0c 100644
--- a/google/pubsub_v1/services/subscriber/transports/grpc.py
+++ b/google/pubsub_v1/services/subscriber/transports/grpc.py
@@ -73,12 +73,11 @@ def intercept_unary_unary(self, continuation, client_call_details, request):
                 f"Sending request for {client_call_details.method}",
                 extra={
                     "serviceName": "google.pubsub.v1.Subscriber",
-                    "rpcName": client_call_details.method,
+                    "rpcName": str(client_call_details.method),
                     "request": grpc_request,
                     "metadata": grpc_request["metadata"],
                 },
             )
-
         response = continuation(client_call_details, request)
         if logging_enabled:  # pragma: NO COVER
             response_metadata = response.trailing_metadata()
diff --git a/google/pubsub_v1/services/subscriber/transports/rest.py b/google/pubsub_v1/services/subscriber/transports/rest.py
index 62211228e..bb0ee68c6 100644
--- a/google/pubsub_v1/services/subscriber/transports/rest.py
+++ b/google/pubsub_v1/services/subscriber/transports/rest.py
@@ -23,6 +23,7 @@
 from google.api_core import rest_helpers
 from google.api_core import rest_streaming
 from google.api_core import gapic_v1
+import google.protobuf
 
 from google.protobuf import json_format
 from google.iam.v1 import iam_policy_pb2  # type: ignore
@@ -61,6 +62,9 @@
     rest_version=f"requests@{requests_version}",
 )
 
+if hasattr(DEFAULT_CLIENT_INFO, "protobuf_runtime_version"):  # pragma: NO COVER
+    DEFAULT_CLIENT_INFO.protobuf_runtime_version = google.protobuf.__version__
+
 
 class SubscriberRestInterceptor:
     """Interceptor for Subscriber.
diff --git a/testing/constraints-3.13.txt b/testing/constraints-3.13.txt
index ad3f0fa58..2010e549c 100644
--- a/testing/constraints-3.13.txt
+++ b/testing/constraints-3.13.txt
@@ -1,7 +1,12 @@
-# -*- coding: utf-8 -*-
-# This constraints file is required for unit tests.
+# We use the constraints file for the latest Python version
+# (currently this file) to check that the latest
+# major versions of dependencies are supported in setup.py.
 # List all library dependencies and extras in this file.
-google-api-core
-proto-plus
-protobuf
-grpc-google-iam-v1
+# Require the latest major version be installed for each dependency.
+# e.g., if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0",
+# Then this file should have google-cloud-foo>=1
+google-api-core>=2
+google-auth>=2
+proto-plus>=1
+protobuf>=6
+grpc-google-iam-v1>=0