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feat: A2A Version Header validation on server side. #865

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Merged
bartek-w merged 1 commit into from
Mar 19, 2026
Merged

feat: A2A Version Header validation on server side. #865

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5 changes: 4 additions & 1 deletion src/a2a/compat/v0_3/jsonrpc_adapter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -38,8 +38,9 @@
from a2a.server.jsonrpc_models import (
JSONRPCError as CoreJSONRPCError,
)
from a2a.utils import constants
from a2a.utils.errors import ExtendedAgentCardNotConfiguredError
from a2a.utils.helpers import maybe_await
from a2a.utils.helpers import maybe_await, validate_version


logger = logging.getLogger(__name__)
Expand Down Expand Up @@ -152,6 +153,7 @@ async def handle_request(
request_id, CoreInternalError(message=str(e))
)

@validate_version(constants.PROTOCOL_VERSION_0_3)
async def _process_non_streaming_request(
self,
request_id: 'str | int | None',
Expand Down Expand Up @@ -266,6 +268,7 @@ async def get_authenticated_extended_card(

return conversions.to_compat_agent_card(card_to_serve)

@validate_version(constants.PROTOCOL_VERSION_0_3)
async def _process_streaming_request(
self,
request_id: 'str | int | None',
Expand Down
16 changes: 15 additions & 1 deletion src/a2a/compat/v0_3/rest_handler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,12 @@
from a2a.compat.v0_3 import types as types_v03
from a2a.compat.v0_3.request_handler import RequestHandler03
from a2a.server.context import ServerCallContext
from a2a.utils.helpers import validate, validate_async_generator
from a2a.utils import constants
from a2a.utils.helpers import (
validate,
validate_async_generator,
validate_version,
)
from a2a.utils.telemetry import SpanKind, trace_class


Expand All @@ -53,6 +58,7 @@ def __init__(
self.agent_card = agent_card
self.handler03 = RequestHandler03(request_handler=request_handler)

@validate_version(constants.PROTOCOL_VERSION_0_3)
async def on_message_send(
self,
request: Request,
Expand All @@ -78,6 +84,7 @@ async def on_message_send(
pb2_v03_resp = proto_utils.ToProto.task_or_message(v03_resp)
return MessageToDict(pb2_v03_resp)

@validate_version(constants.PROTOCOL_VERSION_0_3)
@validate_async_generator(
lambda self: self.agent_card.capabilities.streaming,
'Streaming is not supported by the agent',
Expand Down Expand Up @@ -110,6 +117,7 @@ async def on_message_send_stream(
)
yield MessageToDict(v03_pb_resp)

@validate_version(constants.PROTOCOL_VERSION_0_3)
async def on_cancel_task(
self,
request: Request,
Expand All @@ -134,6 +142,7 @@ async def on_cancel_task(
pb2_v03_task = proto_utils.ToProto.task(v03_resp)
return MessageToDict(pb2_v03_task)

@validate_version(constants.PROTOCOL_VERSION_0_3)
@validate_async_generator(
lambda self: self.agent_card.capabilities.streaming,
'Streaming is not supported by the agent',
Expand Down Expand Up @@ -166,6 +175,7 @@ async def on_subscribe_to_task(
)
yield MessageToDict(v03_pb_resp)

@validate_version(constants.PROTOCOL_VERSION_0_3)
async def get_push_notification(
self,
request: Request,
Expand Down Expand Up @@ -198,6 +208,7 @@ async def get_push_notification(
)
return MessageToDict(pb2_v03_config)

@validate_version(constants.PROTOCOL_VERSION_0_3)
@validate(
lambda self: self.agent_card.capabilities.push_notifications,
'Push notifications are not supported by the agent',
Expand Down Expand Up @@ -242,6 +253,7 @@ async def set_push_notification(
)
return MessageToDict(pb2_v03_config)

@validate_version(constants.PROTOCOL_VERSION_0_3)
async def on_get_task(
self,
request: Request,
Expand Down Expand Up @@ -271,6 +283,7 @@ async def on_get_task(
pb2_v03_task = proto_utils.ToProto.task(v03_resp)
return MessageToDict(pb2_v03_task)

@validate_version(constants.PROTOCOL_VERSION_0_3)
async def list_push_notifications(
self,
request: Request,
Expand All @@ -297,6 +310,7 @@ async def list_push_notifications(

return MessageToDict(pb2_v03_resp)

@validate_version(constants.PROTOCOL_VERSION_0_3)
async def list_tasks(
self,
request: Request,
Expand Down
4 changes: 3 additions & 1 deletion src/a2a/server/apps/jsonrpc/jsonrpc_app.py
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Original file line number Diff line number Diff line change
Expand Up @@ -254,7 +254,7 @@ def __init__( # noqa: PLR0913
agent_card=agent_card,
http_handler=http_handler,
extended_agent_card=extended_agent_card,
context_builder=context_builder,
context_builder=self._context_builder,
card_modifier=card_modifier,
extended_card_modifier=extended_card_modifier,
)
Expand Down Expand Up @@ -444,6 +444,8 @@ async def _handle_requests(self, request: Request) -> Response: # noqa: PLR0911
InvalidRequestError(message='Payload too large'),
)
raise e
except A2AError as e:
return self._generate_error_response(request_id, e)
except Exception as e:
logger.exception('Unhandled exception')
return self._generate_error_response(
Expand Down
19 changes: 17 additions & 2 deletions src/a2a/server/request_handlers/jsonrpc_handler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@
Task,
TaskPushNotificationConfig,
)
from a2a.utils import proto_utils
from a2a.utils import constants, proto_utils
from a2a.utils.errors import (
JSON_RPC_ERROR_CODE_MAP,
A2AError,
Expand All @@ -49,7 +49,12 @@
UnsupportedOperationError,
VersionNotSupportedError,
)
from a2a.utils.helpers import maybe_await, validate, validate_async_generator
from a2a.utils.helpers import (
maybe_await,
validate,
validate_async_generator,
validate_version,
)
from a2a.utils.telemetry import SpanKind, trace_class


Expand Down Expand Up @@ -142,6 +147,7 @@
return None
return context.state.get('request_id')

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def on_message_send(
self,
request: SendMessageRequest,
Expand Down Expand Up @@ -171,6 +177,7 @@
except A2AError as e:
return _build_error_response(request_id, e)

@validate_version(constants.PROTOCOL_VERSION_1_0)
@validate_async_generator(
lambda self: self.agent_card.capabilities.streaming,
'Streaming is not supported by the agent',
Expand All @@ -192,24 +199,25 @@
Dict representations of JSON-RPC responses containing streaming events.
"""
try:
async for event in self.request_handler.on_message_send_stream(
request, context
):
# Wrap the event in StreamResponse for consistent client parsing
stream_response = proto_utils.to_stream_response(event)
result = MessageToDict(
stream_response, preserving_proto_field_name=False
)
yield _build_success_response(
self._get_request_id(context), result
)
except A2AError as e:
yield _build_error_response(
self._get_request_id(context),
e,
)

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def on_cancel_task(

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see src/a2a/server/request_handlers/jsonrpc_handler.py (268-286)
self,
request: CancelTaskRequest,
context: ServerCallContext,
Expand All @@ -225,17 +233,18 @@
"""
request_id = self._get_request_id(context)
try:
task = await self.request_handler.on_cancel_task(request, context)
except A2AError as e:
return _build_error_response(request_id, e)

if task:
result = MessageToDict(task, preserving_proto_field_name=False)
return _build_success_response(request_id, result)

return _build_error_response(request_id, TaskNotFoundError())

@validate_version(constants.PROTOCOL_VERSION_1_0)
@validate_async_generator(

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see src/a2a/server/request_handlers/jsonrpc_handler.py (367-378)
lambda self: self.agent_card.capabilities.streaming,
'Streaming is not supported by the agent',
)
Expand All @@ -256,24 +265,25 @@
Dict representations of JSON-RPC responses containing streaming events.
"""
try:
async for event in self.request_handler.on_subscribe_to_task(
request, context
):
# Wrap the event in StreamResponse for consistent client parsing
stream_response = proto_utils.to_stream_response(event)
result = MessageToDict(
stream_response, preserving_proto_field_name=False
)
yield _build_success_response(
self._get_request_id(context), result
)
except A2AError as e:
yield _build_error_response(
self._get_request_id(context),
e,
)

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def get_push_notification_config(

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see src/a2a/server/request_handlers/jsonrpc_handler.py (202-220)
self,
request: GetTaskPushNotificationConfigRequest,
context: ServerCallContext,
Expand All @@ -299,6 +309,7 @@
except A2AError as e:
return _build_error_response(request_id, e)

@validate_version(constants.PROTOCOL_VERSION_1_0)
@validate(
lambda self: self.agent_card.capabilities.push_notifications,
'Push notifications are not supported by the agent',
Expand Down Expand Up @@ -336,6 +347,7 @@
except A2AError as e:
return _build_error_response(request_id, e)

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def on_get_task(
self,
request: GetTaskRequest,
Expand All @@ -352,17 +364,18 @@
"""
request_id = self._get_request_id(context)
try:
task = await self.request_handler.on_get_task(request, context)
except A2AError as e:
return _build_error_response(request_id, e)

if task:
result = MessageToDict(task, preserving_proto_field_name=False)
return _build_success_response(request_id, result)

return _build_error_response(request_id, TaskNotFoundError())

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def list_tasks(

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see src/a2a/server/request_handlers/jsonrpc_handler.py (236-247)
self,
request: ListTasksRequest,
context: ServerCallContext,
Expand Down Expand Up @@ -390,6 +403,7 @@
except A2AError as e:
return _build_error_response(request_id, e)

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def list_push_notification_configs(
self,
request: ListTaskPushNotificationConfigsRequest,
Expand All @@ -415,6 +429,7 @@
except A2AError as e:
return _build_error_response(request_id, e)

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def delete_push_notification_config(
self,
request: DeleteTaskPushNotificationConfigRequest,
Expand Down
18 changes: 16 additions & 2 deletions src/a2a/server/request_handlers/rest_handler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -27,9 +27,13 @@
GetTaskPushNotificationConfigRequest,
SubscribeToTaskRequest,
)
from a2a.utils import proto_utils
from a2a.utils import constants, proto_utils
from a2a.utils.errors import TaskNotFoundError
from a2a.utils.helpers import validate, validate_async_generator
from a2a.utils.helpers import (
validate,
validate_async_generator,
validate_version,
)
from a2a.utils.telemetry import SpanKind, trace_class


Expand Down Expand Up @@ -61,6 +65,7 @@ def __init__(
self.agent_card = agent_card
self.request_handler = request_handler

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def on_message_send(
self,
request: Request,
Expand All @@ -87,6 +92,7 @@ async def on_message_send(
response = a2a_pb2.SendMessageResponse(message=task_or_message)
return MessageToDict(response)

@validate_version(constants.PROTOCOL_VERSION_1_0)
@validate_async_generator(
lambda self: self.agent_card.capabilities.streaming,
'Streaming is not supported by the agent',
Expand Down Expand Up @@ -117,6 +123,7 @@ async def on_message_send_stream(
response = proto_utils.to_stream_response(event)
yield MessageToDict(response)

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def on_cancel_task(
self,
request: Request,
Expand All @@ -139,6 +146,7 @@ async def on_cancel_task(
return MessageToDict(task)
raise TaskNotFoundError

@validate_version(constants.PROTOCOL_VERSION_1_0)
@validate_async_generator(
lambda self: self.agent_card.capabilities.streaming,
'Streaming is not supported by the agent',
Expand All @@ -165,6 +173,7 @@ async def on_subscribe_to_task(
):
yield MessageToDict(proto_utils.to_stream_response(event))

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def get_push_notification(
self,
request: Request,
Expand Down Expand Up @@ -192,6 +201,7 @@ async def get_push_notification(
)
return MessageToDict(config)

@validate_version(constants.PROTOCOL_VERSION_1_0)
@validate(
lambda self: self.agent_card.capabilities.push_notifications,
'Push notifications are not supported by the agent',
Expand Down Expand Up @@ -229,6 +239,7 @@ async def set_push_notification(
)
return MessageToDict(config)

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def on_get_task(
self,
request: Request,
Expand All @@ -251,6 +262,7 @@ async def on_get_task(
return MessageToDict(task)
raise TaskNotFoundError

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def delete_push_notification(
self,
request: Request,
Expand All @@ -275,6 +287,7 @@ async def delete_push_notification(
)
return {}

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def list_tasks(
self,
request: Request,
Expand All @@ -295,6 +308,7 @@ async def list_tasks(
result = await self.request_handler.on_list_tasks(params, context)
return MessageToDict(result, always_print_fields_with_no_presence=True)

@validate_version(constants.PROTOCOL_VERSION_1_0)
async def list_push_notifications(
self,
request: Request,
Expand Down
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