From 20a4eea27e71cfc5933670b73747fb46d66dd41d Mon Sep 17 00:00:00 2001 From: Sameer Kankute Date: Thu, 5 Mar 2026 14:28:28 +0530 Subject: [PATCH] feat(agents): forward custom headers to backend A2A agents In invoke_agent_a2a: - Extract admin-configured extra_headers from client request by name - Extract convention-based headers (x-a2a-{agent_id/name}-{header}) from client request - Merge with static_headers (static wins on conflict) - Pass merged headers down to asend_message and _handle_stream_message In asend_message / asend_message_streaming: - Accept agent_extra_headers kwarg - Overlay onto LiteLLM internal headers before creating the httpx client Co-Authored-By: Claude Sonnet 4.6 --- litellm/a2a_protocol/main.py | 14 ++++++- .../proxy/agent_endpoints/a2a_endpoints.py | 37 ++++++++++++++++++- 2 files changed, 48 insertions(+), 3 deletions(-) diff --git a/litellm/a2a_protocol/main.py b/litellm/a2a_protocol/main.py index 485b57e311b..6ac88d3a430 100644 --- a/litellm/a2a_protocol/main.py +++ b/litellm/a2a_protocol/main.py @@ -169,6 +169,7 @@ async def asend_message( api_base: Optional[str] = None, litellm_params: Optional[Dict[str, Any]] = None, agent_id: Optional[str] = None, + agent_extra_headers: Optional[Dict[str, str]] = None, **kwargs: Any, ) -> LiteLLMSendMessageResponse: """ @@ -250,9 +251,12 @@ async def asend_message( "Either a2a_client or api_base is required for standard A2A flow" ) trace_id = trace_id or str(uuid.uuid4()) - extra_headers = {"X-LiteLLM-Trace-Id": trace_id} + extra_headers: Dict[str, str] = {"X-LiteLLM-Trace-Id": trace_id} if agent_id: extra_headers["X-LiteLLM-Agent-Id"] = agent_id + # Overlay agent-level headers (agent headers take precedence over LiteLLM internal ones) + if agent_extra_headers: + extra_headers.update(agent_extra_headers) a2a_client = await create_a2a_client( base_url=api_base, extra_headers=extra_headers ) @@ -426,6 +430,7 @@ async def asend_message_streaming( agent_id: Optional[str] = None, metadata: Optional[Dict[str, Any]] = None, proxy_server_request: Optional[Dict[str, Any]] = None, + agent_extra_headers: Optional[Dict[str, str]] = None, ) -> AsyncIterator[Any]: """ Async: Send a streaming message to an A2A agent. @@ -507,7 +512,12 @@ async def asend_message_streaming( raise ValueError( "Either a2a_client or api_base is required for standard A2A flow" ) - a2a_client = await create_a2a_client(base_url=api_base) + streaming_extra_headers: Optional[Dict[str, str]] = None + if agent_extra_headers: + streaming_extra_headers = dict(agent_extra_headers) + a2a_client = await create_a2a_client( + base_url=api_base, extra_headers=streaming_extra_headers + ) # Type assertion: a2a_client is guaranteed to be non-None here assert a2a_client is not None diff --git a/litellm/proxy/agent_endpoints/a2a_endpoints.py b/litellm/proxy/agent_endpoints/a2a_endpoints.py index 6bcee14f29e..344070d17fc 100644 --- a/litellm/proxy/agent_endpoints/a2a_endpoints.py +++ b/litellm/proxy/agent_endpoints/a2a_endpoints.py @@ -6,13 +6,14 @@ The A2A SDK can point to LiteLLM's URL and invoke agents registered with LiteLLM """ import json -from typing import Any, Optional +from typing import Any, Dict, Optional from fastapi import APIRouter, Depends, HTTPException, Request, Response from fastapi.responses import JSONResponse, StreamingResponse from litellm._logging import verbose_proxy_logger from litellm.proxy._types import UserAPIKeyAuth +from litellm.proxy.agent_endpoints.utils import merge_agent_headers from litellm.proxy.auth.user_api_key_auth import user_api_key_auth from litellm.types.utils import all_litellm_params @@ -55,6 +56,7 @@ async def _handle_stream_message( metadata: Optional[dict] = None, proxy_server_request: Optional[dict] = None, *, + agent_extra_headers: Optional[Dict[str, str]] = None, user_api_key_dict: Optional[UserAPIKeyAuth] = None, request_data: Optional[dict] = None, proxy_logging_obj: Optional[Any] = None, @@ -105,6 +107,7 @@ async def _handle_stream_message( agent_id=agent_id, metadata=metadata, proxy_server_request=proxy_server_request, + agent_extra_headers=agent_extra_headers, ) if ( @@ -385,6 +388,36 @@ async def invoke_agent_a2a( version=version, ) + # Build merged headers for the backend agent + static_headers: Dict[str, str] = dict(agent.static_headers or {}) + + raw_headers = dict(request.headers) + normalized = {k.lower(): v for k, v in raw_headers.items()} + + dynamic_headers: Dict[str, str] = {} + + # 1. Admin-configured extra_headers: forward named headers from client request + if agent.extra_headers: + for header_name in agent.extra_headers: + val = normalized.get(header_name.lower()) + if val is not None: + dynamic_headers[header_name] = val + + # 2. Convention-based forwarding: x-a2a-{agent_id_or_name}-{header_name} + # Matches both agent_id (UUID) and agent_name (alias), case-insensitive. + for alias in (agent.agent_id.lower(), agent.agent_name.lower()): + prefix = f"x-a2a-{alias}-" + for key, val in normalized.items(): + if key.startswith(prefix): + header_name = key[len(prefix) :] + if header_name: + dynamic_headers[header_name] = val + + agent_extra_headers = merge_agent_headers( + dynamic_headers=dynamic_headers or None, + static_headers=static_headers or None, + ) + # Route through SDK functions if method == "message/send": from a2a.types import MessageSendParams, SendMessageRequest @@ -401,6 +434,7 @@ async def invoke_agent_a2a( metadata=data.get("metadata", {}), proxy_server_request=data.get("proxy_server_request"), litellm_logging_obj=logging_obj, + agent_extra_headers=agent_extra_headers, ) response = await proxy_logging_obj.post_call_success_hook( @@ -425,6 +459,7 @@ async def invoke_agent_a2a( agent_id=agent.agent_id, metadata=data.get("metadata", {}), proxy_server_request=data.get("proxy_server_request"), + agent_extra_headers=agent_extra_headers, user_api_key_dict=user_api_key_dict, request_data=data, proxy_logging_obj=proxy_logging_obj,