init: A2AConfig

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Ishaan Jaffer 2026-02-03 12:26:00 -08:00
parent b6c8f13592
commit 403aadd564

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"""
A2A Protocol Transformation for LiteLLM
"""
import uuid
from typing import Any, Dict, Iterator, List, Optional, Union, cast
import httpx
from pydantic import BaseModel
from litellm.llms.base_llm.base_model_iterator import BaseModelResponseIterator
from litellm.llms.base_llm.chat.transformation import BaseConfig, BaseLLMException
from litellm.types.llms.openai import AllMessageValues
from litellm.types.utils import Choices, Message, ModelResponse
from ..common_utils import A2AError, extract_text_from_a2a_response
from .streaming_iterator import A2AModelResponseIterator
class A2AConfig(BaseConfig):
"""
Configuration for A2A (Agent-to-Agent) Protocol.
Handles transformation between OpenAI and A2A JSON-RPC 2.0 formats.
"""
def get_supported_openai_params(self, model: str) -> List[str]:
"""Return list of supported OpenAI parameters"""
return [
"stream",
"temperature",
"max_tokens",
"top_p",
]
def map_openai_params(
self,
non_default_params: dict,
optional_params: dict,
model: str,
drop_params: bool,
) -> dict:
"""
Map OpenAI parameters to A2A parameters.
For A2A protocol, we don't need to map most parameters since
they're handled in the transform_request method.
"""
return optional_params
def validate_environment(
self,
headers: dict,
model: str,
messages: List[AllMessageValues],
optional_params: dict,
litellm_params: dict,
api_key: Optional[str] = None,
api_base: Optional[str] = None,
) -> dict:
"""
Validate environment and set headers for A2A requests.
Args:
headers: Request headers dict
model: Model name
messages: Messages list
optional_params: Optional parameters
litellm_params: LiteLLM parameters
api_key: API key (optional for A2A)
api_base: API base URL
Returns:
Updated headers dict
"""
# Ensure Content-Type is set to application/json for JSON-RPC 2.0
if "content-type" not in headers and "Content-Type" not in headers:
headers["Content-Type"] = "application/json"
# Add Authorization header if API key is provided
if api_key is not None:
headers["Authorization"] = f"Bearer {api_key}"
return headers
def get_complete_url(
self,
api_base: Optional[str],
api_key: Optional[str],
model: str,
optional_params: dict,
litellm_params: dict,
stream: Optional[bool] = None,
) -> str:
"""
Get the complete A2A agent endpoint URL.
A2A agents use JSON-RPC 2.0 at the base URL, not specific paths.
The method (message/send or message/stream) is specified in the
JSON-RPC request body, not in the URL.
Args:
api_base: Base URL of the A2A agent (e.g., "http://0.0.0.0:9999")
api_key: API key (not used for URL construction)
model: Model name (not used for A2A, agent determined by api_base)
optional_params: Optional parameters
litellm_params: LiteLLM parameters
stream: Whether this is a streaming request (affects JSON-RPC method)
Returns:
Complete URL for the A2A endpoint (base URL)
"""
if api_base is None:
raise ValueError("api_base is required for A2A provider")
# A2A uses JSON-RPC 2.0 at the base URL
# Remove trailing slash for consistency
return api_base.rstrip("/")
def transform_request(
self,
model: str,
messages: List[AllMessageValues],
optional_params: dict,
litellm_params: dict,
headers: dict,
) -> dict:
"""
Transform OpenAI request to A2A JSON-RPC 2.0 format.
Args:
model: Model name
messages: List of OpenAI messages
optional_params: Optional parameters
litellm_params: LiteLLM parameters
headers: Request headers
Returns:
A2A JSON-RPC 2.0 request dict
"""
# Generate request ID
request_id = str(uuid.uuid4())
# Convert last message to A2A format (A2A protocol typically sends single message)
# For multi-turn conversations, we'd need to handle context differently
if not messages:
raise ValueError("At least one message is required for A2A completion")
last_message = messages[-1]
# Convert to dict if needed
msg_dict: Dict[str, Any]
if isinstance(last_message, BaseModel):
msg_dict = last_message.model_dump()
elif isinstance(last_message, dict):
msg_dict = cast(Dict[str, Any], last_message)
else:
msg_dict = dict(last_message) # type: ignore
# Transform to A2A message format
a2a_message = self._openai_message_to_a2a_message(msg_dict)
# Build JSON-RPC 2.0 request
# For A2A protocol, the method is "message/send" for non-streaming
# and "message/stream" for streaming (handled by optional_params["stream"])
method = "message/stream" if optional_params.get("stream") else "message/send"
request_data = {
"jsonrpc": "2.0",
"id": request_id,
"method": method,
"params": {
"message": a2a_message
}
}
return request_data
def transform_response(
self,
model: str,
raw_response: httpx.Response,
model_response: ModelResponse,
logging_obj: Any,
request_data: dict,
messages: List[AllMessageValues],
optional_params: dict,
litellm_params: dict,
encoding: Any,
api_key: Optional[str] = None,
json_mode: Optional[bool] = None,
) -> ModelResponse:
"""
Transform A2A JSON-RPC 2.0 response to OpenAI format.
Args:
model: Model name
raw_response: HTTP response from A2A agent
model_response: Model response object to populate
logging_obj: Logging object
request_data: Original request data
messages: Original messages
optional_params: Optional parameters
litellm_params: LiteLLM parameters
encoding: Encoding object
api_key: API key
json_mode: JSON mode flag
Returns:
Populated ModelResponse object
"""
try:
response_json = raw_response.json()
except Exception as e:
raise A2AError(
status_code=raw_response.status_code,
message=f"Failed to parse A2A response: {str(e)}",
headers=dict(raw_response.headers),
)
# Check for JSON-RPC error
if "error" in response_json:
error = response_json["error"]
raise A2AError(
status_code=raw_response.status_code,
message=f"A2A error: {error.get('message', 'Unknown error')}",
headers=dict(raw_response.headers),
)
# Extract text from A2A response
text = extract_text_from_a2a_response(response_json)
# Populate model response
model_response.choices = [
Choices(
finish_reason="stop",
index=0,
message=Message(
content=text,
role="assistant",
),
)
]
# Set model
model_response.model = model
# Set ID from response
model_response.id = response_json.get("id", str(uuid.uuid4()))
return model_response
def get_model_response_iterator(
self,
streaming_response: Union[Iterator, Any],
sync_stream: bool,
json_mode: Optional[bool] = False,
) -> BaseModelResponseIterator:
"""
Get streaming iterator for A2A responses.
Args:
streaming_response: Streaming response iterator
sync_stream: Whether this is a sync stream
json_mode: JSON mode flag
Returns:
A2A streaming iterator
"""
return A2AModelResponseIterator(
streaming_response=streaming_response,
sync_stream=sync_stream,
json_mode=json_mode,
)
def _openai_message_to_a2a_message(self, message: Dict[str, Any]) -> Dict[str, Any]:
"""
Convert OpenAI message to A2A message format.
Args:
message: OpenAI message dict
Returns:
A2A message dict
"""
content = message.get("content", "")
role = message.get("role", "user")
return {
"role": role,
"parts": [{"kind": "text", "text": str(content)}],
"messageId": str(uuid.uuid4()),
}
def get_error_class(
self, error_message: str, status_code: int, headers: Union[dict, httpx.Headers]
) -> BaseLLMException:
"""Return appropriate error class for A2A errors"""
# Convert headers to dict if needed
headers_dict = dict(headers) if isinstance(headers, httpx.Headers) else headers
return A2AError(
status_code=status_code,
message=error_message,
headers=headers_dict,
)