[DRAFT] feat!: Upgrade A2A to v1.0

buf.gen.yaml

@@ -2,7 +2,7 @@
 version: v2
 inputs:
   - git_repo: https://github.com/a2aproject/A2A.git
-    ref: main
+    ref: transports
     subdir: specification/grpc
 managed:
   enabled: true
@@ -21,11 +21,11 @@ plugins:
   # Generate python protobuf related code
   # Generates *_pb2.py files, one for each .proto
   - remote: buf.build/protocolbuffers/python:v29.3
-    out: src/a2a/grpc
+    out: src/a2a/types
   # Generate python service code.
   # Generates *_pb2_grpc.py
   - remote: buf.build/grpc/python
-    out: src/a2a/grpc
+    out: src/a2a/types
   # Generates *_pb2.pyi files.
   - remote: buf.build/protocolbuffers/pyi
-    out: src/a2a/grpc
+    out: src/a2a/types

pyproject.toml

@@ -13,6 +13,7 @@ dependencies = [
   "pydantic>=2.11.3",
   "protobuf>=5.29.5",
   "google-api-core>=1.26.0",
+  "json-rpc>=1.15.0",
 ]
 
 classifiers = [
@@ -114,7 +115,7 @@ explicit = true
 
 [tool.mypy]
 plugins = ["pydantic.mypy"]
-exclude = ["src/a2a/grpc/"]
+exclude = ["src/a2a/types/a2a_pb2\\.py", "src/a2a/types/a2a_pb2_grpc\\.py"]
 disable_error_code = [
   "import-not-found",
   "annotation-unchecked",
@@ -134,7 +135,8 @@ exclude = [
   "**/node_modules",
   "**/venv",
   "**/.venv",
-  "src/a2a/grpc/",
+  "src/a2a/types/a2a_pb2.py",
+  "src/a2a/types/a2a_pb2_grpc.py",
 ]
 reportMissingImports = "none"
 reportMissingModuleSource = "none"
@@ -145,7 +147,8 @@ omit = [
     "*/tests/*",
     "*/site-packages/*",
     "*/__init__.py",
-    "src/a2a/grpc/*",
+    "src/a2a/types/a2a_pb2.py",
+    "src/a2a/types/a2a_pb2_grpc.py",
 ]
 
 [tool.coverage.report]
@@ -257,7 +260,9 @@ exclude = [
     "node_modules",
     "venv",
     "*/migrations/*",
-    "src/a2a/grpc/**",
+    "src/a2a/types/a2a_pb2.py",
+    "src/a2a/types/a2a_pb2.pyi",
+    "src/a2a/types/a2a_pb2_grpc.py",
     "tests/**",
 ]
 
@@ -311,7 +316,9 @@ inline-quotes = "single"
 
 [tool.ruff.format]
 exclude = [
-    "src/a2a/grpc/**",
+    "src/a2a/types/a2a_pb2.py",
+    "src/a2a/types/a2a_pb2.pyi",
+    "src/a2a/types/a2a_pb2_grpc.py",
 ]
 docstring-code-format = true
 docstring-code-line-length = "dynamic"

src/a2a/client/__init__.py

@@ -18,39 +18,18 @@
     A2AClientTimeoutError,
 )
 from a2a.client.helpers import create_text_message_object
-from a2a.client.legacy import A2AClient
 from a2a.client.middleware import ClientCallContext, ClientCallInterceptor
 
 
 logger = logging.getLogger(__name__)
 
-try:
-    from a2a.client.legacy_grpc 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',
     'A2AClientError',
     'A2AClientHTTPError',
     'A2AClientJSONError',
     'A2AClientTimeoutError',
-    'A2AGrpcClient',
     'AuthInterceptor',
     'BaseClient',
     'Client',

src/a2a/client/auth/interceptor.py

@@ -3,18 +3,34 @@
 
 from a2a.client.auth.credentials import CredentialService
 from a2a.client.middleware import ClientCallContext, ClientCallInterceptor
-from a2a.types import (
+from a2a.types.a2a_pb2 import (
     AgentCard,
     APIKeySecurityScheme,
     HTTPAuthSecurityScheme,
-    In,
     OAuth2SecurityScheme,
     OpenIdConnectSecurityScheme,
+    SecurityScheme,
 )
 
 logger = logging.getLogger(__name__)
 
 
+def _get_security_scheme_value(scheme: SecurityScheme):
+    """Extract the actual security scheme from the oneof union."""
+    which = scheme.WhichOneof('scheme')
+    if which == 'api_key_security_scheme':
+        return scheme.api_key_security_scheme
+    elif which == 'http_auth_security_scheme':
+        return scheme.http_auth_security_scheme
+    elif which == 'oauth2_security_scheme':
+        return scheme.oauth2_security_scheme
+    elif which == 'open_id_connect_security_scheme':
+        return scheme.open_id_connect_security_scheme
+    elif which == 'mtls_security_scheme':
+        return scheme.mtls_security_scheme
+    return None
+
+
 class AuthInterceptor(ClientCallInterceptor):
     """An interceptor that automatically adds authentication details to requests.
 
@@ -35,13 +51,13 @@ async def intercept(
         """Applies authentication headers to the request if credentials are available."""
         if (
             agent_card is None
-            or agent_card.security is None
-            or agent_card.security_schemes is None
+            or not agent_card.security
+            or not agent_card.security_schemes
         ):
             return request_payload, http_kwargs
 
         for requirement in agent_card.security:
-            for scheme_name in requirement:
+            for scheme_name in requirement.schemes:
                 credential = await self._credential_service.get_credentials(
                     scheme_name, context
                 )
@@ -51,7 +67,9 @@ async def intercept(
                     )
                     if not scheme_def_union:
                         continue
-                    scheme_def = scheme_def_union.root
+                    scheme_def = _get_security_scheme_value(scheme_def_union)
+                    if not scheme_def:
+                        continue
 
                     headers = http_kwargs.get('headers', {})
 
@@ -62,9 +80,8 @@ async def intercept(
                         ):
                             headers['Authorization'] = f'Bearer {credential}'
                             logger.debug(
-                                "Added Bearer token for scheme '%s' (type: %s).",
+                                "Added Bearer token for scheme '%s'.",
                                 scheme_name,
-                                scheme_def.type,
                             )
                             http_kwargs['headers'] = headers
                             return request_payload, http_kwargs
@@ -76,15 +93,14 @@ async def intercept(
                         ):
                             headers['Authorization'] = f'Bearer {credential}'
                             logger.debug(
-                                "Added Bearer token for scheme '%s' (type: %s).",
+                                "Added Bearer token for scheme '%s'.",
                                 scheme_name,
-                                scheme_def.type,
                             )
                             http_kwargs['headers'] = headers
                             return request_payload, http_kwargs
 
                         # Case 2: API Key in Header
-                        case APIKeySecurityScheme(in_=In.header):
+                        case APIKeySecurityScheme() if scheme_def.location.lower() == 'header':
                             headers[scheme_def.name] = credential
                             logger.debug(
                                 "Added API Key Header for scheme '%s'.",