fix: Prevent import grpc issues for Client after making dependencies optional (#330)

Follow-up to #322

Fixes #326

Author: holtskinner

src/a2a/client/__init__.py

@@ -1,5 +1,7 @@
 """Client-side components for interacting with an A2A agent."""
 
+import logging
+
 from a2a.client.auth import (
     AuthInterceptor,
     CredentialService,
@@ -12,11 +14,31 @@
     A2AClientJSONError,
     A2AClientTimeoutError,
 )
-from a2a.client.grpc_client import A2AGrpcClient
 from a2a.client.helpers import create_text_message_object
 from a2a.client.middleware import ClientCallContext, ClientCallInterceptor
 
 
+logger = logging.getLogger(__name__)
+
+try:
+    from a2a.client.grpc_client import A2AGrpcClient  # type: ignore
+except ImportError as e:
+    _original_error = e
+    logger.debug(
+        'A2AGrpcClient not loaded. This is expected if gRPC dependencies are not installed. Error: %s',
+        _original_error,
+    )
+
+    class A2AGrpcClient:  # type: ignore
+        """Placeholder for A2AGrpcClient when dependencies are not installed."""
+
+        def __init__(self, *args, **kwargs):
+            raise ImportError(
+                'To use A2AGrpcClient, its dependencies must be installed. '
+                'You can install them with \'pip install "a2a-sdk[grpc]"\''
+            ) from _original_error
+
+
 __all__ = [
     'A2ACardResolver',
     'A2AClient',

src/a2a/client/grpc_client.py

@@ -2,7 +2,16 @@
 
 from collections.abc import AsyncGenerator
 
-import grpc
+
+try:
+    import grpc
+except ImportError as e:
+    raise ImportError(
+        'A2AGrpcClient requires grpcio and grpcio-tools to be installed. '
+        'Install with: '
+        "'pip install a2a-sdk[grpc]'"
+    ) from e
+
 
 from a2a.grpc import a2a_pb2, a2a_pb2_grpc
 from a2a.types import (

src/a2a/server/request_handlers/__init__.py

@@ -23,6 +23,7 @@
     _original_error = e
     logger.debug(
         'GrpcHandler not loaded. This is expected if gRPC dependencies are not installed. Error: %s',
+        _original_error,
     )
 
     class GrpcHandler:  # type: ignore