diff --git a/litellm/a2a_protocol/litellm_completion_bridge/handler.py b/litellm/a2a_protocol/litellm_completion_bridge/handler.py
index d4708e02786..04f013e86c6 100644
--- a/litellm/a2a_protocol/litellm_completion_bridge/handler.py
+++ b/litellm/a2a_protocol/litellm_completion_bridge/handler.py
@@ -89,11 +89,12 @@ class A2ACompletionBridgeHandler:
             "api_base": api_base,
             "stream": stream,
         }
+        configured_headers: Final[object] = litellm_params.get("extra_headers") or litellm_params.get("headers")
         # Add litellm_params (contains api_key, client_id, client_secret, tenant_id, etc.)
         litellm_params_to_add: Final = {
             k: v
             for k, v in litellm_params.items()
-            if k not in ("model", "custom_llm_provider") and k not in _AGENT_ONLY_PARAMS
+            if k not in ("model", "custom_llm_provider", "extra_headers", "headers") and k not in _AGENT_ONLY_PARAMS
         }
         completion_params.update(litellm_params_to_add)
         # Apply forward metadata AFTER the litellm_params merge so the helper
@@ -105,10 +106,10 @@ class A2ACompletionBridgeHandler:
             params=params,
         )
 
-        if agent_extra_headers:
+        if agent_extra_headers or configured_headers:
             completion_params["extra_headers"] = merge_agent_headers(
                 dynamic_headers=agent_extra_headers,
-                static_headers=completion_params.get("extra_headers"),
+                static_headers=configured_headers if isinstance(configured_headers, Mapping) else None,
             )
 
         return completion_params
@@ -361,6 +362,7 @@ class A2ACompletionBridgeHandler:
                             artifact_event: Final = A2ACompletionBridgeTransformation.create_artifact_update_event(
                                 ctx=ctx,
                                 text=content,
+                                index=choice_index,
                             )
                             yield artifact_event
         finally:
@@ -380,13 +382,10 @@ class A2ACompletionBridgeHandler:
             completed_event["result"]["finish_reason"] = stream_finish_reason
         if stream_usage is not None:
             completed_event["usage"] = stream_usage
-        if choice_delta_fields.get(0):
-            completed_event["result"].update(choice_delta_fields[0])
-        if 0 in choice_logprobs:
-            completed_event["result"]["logprobs"] = choice_logprobs[0]
         if len(choice_texts) > 1:
-            completed_event["result"]["choices"] = [
-                {
+            choice_payloads: list[dict[str, object]] = []
+            for choice_index in sorted(choice_texts):
+                choice_payload: dict[str, object] = {
                     "index": choice_index,
                     "message": {
                         "kind": "message",
@@ -397,7 +396,6 @@ class A2ACompletionBridgeHandler:
                             if choice_tool_calls.get(choice_index)
                             else {}
                         ),
-                        **choice_delta_fields.get(choice_index, {}),
                     },
                     **(
                         {"finish_reason": choice_finish_reasons[choice_index]}
@@ -406,8 +404,29 @@ class A2ACompletionBridgeHandler:
                     ),
                     **({"logprobs": choice_logprobs[choice_index]} if choice_index in choice_logprobs else {}),
                 }
-                for choice_index in sorted(choice_texts)
-            ]
+                if choice_delta_fields.get(choice_index):
+                    choice_payload["delta"] = choice_delta_fields[choice_index]
+                choice_payloads.append(choice_payload)
+            completed_event["result"]["choices"] = choice_payloads
+        else:
+            metadata_indices = sorted(set(choice_delta_fields) | set(choice_logprobs))
+            if metadata_indices:
+                completed_event["result"]["choices"] = [
+                    {
+                        "index": choice_index,
+                        **(
+                            {"delta": choice_delta_fields[choice_index]}
+                            if choice_delta_fields.get(choice_index)
+                            else {}
+                        ),
+                        **(
+                            {"logprobs": choice_logprobs[choice_index]}
+                            if choice_index in choice_logprobs
+                            else {}
+                        ),
+                    }
+                    for choice_index in metadata_indices
+                ]
         yield completed_event
 
         verbose_logger.info(
diff --git a/litellm/a2a_protocol/litellm_completion_bridge/transformation.py b/litellm/a2a_protocol/litellm_completion_bridge/transformation.py
index 02006e98fa0..6e11acb71a6 100644
--- a/litellm/a2a_protocol/litellm_completion_bridge/transformation.py
+++ b/litellm/a2a_protocol/litellm_completion_bridge/transformation.py
@@ -262,6 +262,10 @@ class A2ACompletionBridgeTransformation:
         }
         if usage is not None:
             a2a_response["usage"] = usage.model_dump(exclude_none=True) if hasattr(usage, "model_dump") else usage
+        for field in ("system_fingerprint", "service_tier"):
+            value = getattr(response, field, None)
+            if value is not None:
+                a2a_response[field] = value
         if len(serialized_choices) > 1:
             a2a_response["choices"] = serialized_choices
 
@@ -354,6 +358,7 @@ class A2ACompletionBridgeTransformation:
     def create_artifact_update_event(
         ctx: A2AStreamingContext,
         text: str,
+        index: int | None = None,
     ) -> dict[str, Any]:
         """
         Create an artifact update event with content.
@@ -362,15 +367,18 @@ class A2ACompletionBridgeTransformation:
             ctx: Streaming context
             text: The text content for the artifact
         """
+        artifact: Final[dict[str, Any]] = {
+            "artifactId": str(uuid4()),
+            "name": "response",
+            "parts": [{"kind": "text", "text": text}],
+        }
+        if index is not None:
+            artifact["index"] = index
         return {
             "id": ctx.request_id,
             "jsonrpc": "2.0",
             "result": {
-                "artifact": {
-                    "artifactId": str(uuid4()),
-                    "name": "response",
-                    "parts": [{"kind": "text", "text": text}],
-                },
+                "artifact": artifact,
                 "contextId": ctx.context_id,
                 "kind": "artifact-update",
                 "taskId": ctx.task_id,
diff --git a/litellm/llms/a2a/chat/streaming_iterator.py b/litellm/llms/a2a/chat/streaming_iterator.py
index 1a598bb7a50..605c8cbd375 100644
--- a/litellm/llms/a2a/chat/streaming_iterator.py
+++ b/litellm/llms/a2a/chat/streaming_iterator.py
@@ -71,6 +71,16 @@ class A2AModelResponseIterator(BaseModelResponseIterator):
         try:
             # Extract text from A2A response
             result: Final = chunk.get("result", {})
+            chunk_index = 0
+            if isinstance(result, Mapping):
+                artifact = result.get("artifact")
+                if isinstance(artifact, Mapping) and isinstance(artifact.get("index"), int):
+                    chunk_index = artifact["index"]
+                choices = result.get("choices")
+                if isinstance(choices, list) and choices and isinstance(choices[0], Mapping):
+                    raw_index = choices[0].get("index")
+                    if isinstance(raw_index, int):
+                        chunk_index = raw_index
             status: Final = result.get("status", {}) if isinstance(result, Mapping) else {}
             is_working_status: Final = (
                 isinstance(result, Mapping)
@@ -132,7 +142,7 @@ class A2AModelResponseIterator(BaseModelResponseIterator):
                 is_finished=bool(finish_reason or tool_calls),
                 finish_reason=finish_reason or ("tool_calls" if tool_calls else ""),
                 usage=usage,
-                index=0,
+                index=chunk_index,
                 tool_use=tool_calls,
                 provider_specific_fields=provider_fields or None,
             )
diff --git a/litellm/proxy/agent_endpoints/a2a_endpoints.py b/litellm/proxy/agent_endpoints/a2a_endpoints.py
index bd02cfdf907..ef36296fff5 100644
--- a/litellm/proxy/agent_endpoints/a2a_endpoints.py
+++ b/litellm/proxy/agent_endpoints/a2a_endpoints.py
@@ -860,7 +860,7 @@ async def invoke_agent_a2a(
                 _enqueue_fn: Final = getattr(logging_obj, "_enqueue_deferred_logging", None)
                 if _enqueue_fn is not None:
                     logging_obj._enqueue_deferred_logging = None
-                    _enqueue_fn()
+                    _enqueue_fn(response)
 
             response_dict: Final[dict[str, Any]] = (
                 response.model_dump(mode="json", exclude_none=True)
diff --git a/litellm/proxy/agent_endpoints/a2a_routing.py b/litellm/proxy/agent_endpoints/a2a_routing.py
index ff8381c6531..b1af6121839 100644
--- a/litellm/proxy/agent_endpoints/a2a_routing.py
+++ b/litellm/proxy/agent_endpoints/a2a_routing.py
@@ -37,6 +37,7 @@ _FORWARDED_REQUEST_PARAMS: Final = frozenset(
         "frequency_penalty",
         "functions",
         "function_call",
+        "guided_json",
         "include_server_side_tool_invocations",
         "logit_bias",
         "logprobs",
@@ -305,6 +306,10 @@ async def _route_registered_provider(
         id=str(response.get("id") or request_id),
         model=model_name,
         choices=model_choices,
+        system_fingerprint=response.get("system_fingerprint")
+        if isinstance(response.get("system_fingerprint"), str)
+        else None,
+        service_tier=response.get("service_tier") if isinstance(response.get("service_tier"), str) else None,
     )
     raw_usage: Final = response.get("usage")
     usage: Final = litellm.Usage(**raw_usage) if isinstance(raw_usage, Mapping) else raw_usage
@@ -315,10 +320,10 @@ async def _route_registered_provider(
 
     if isinstance(logging_obj, Logging):
 
-        def _enqueue_logging() -> None:
+        def _enqueue_logging(final_response: ModelResponse | None = None) -> None:
             asyncio.create_task(
                 logging_obj.dispatch_success_handlers(
-                    model_response,
+                    final_response if final_response is not None else model_response,
                     cache_hit=False,
                     prefer_async_handlers=True,
                 )
@@ -544,7 +549,7 @@ async def route_a2a_agent_request(
         else registered_params_value or {}
     )
     configured_api_base: Final = registered_params_value.get("api_base") if registered_params_value else None
-    api_base: Final = configured_api_base if isinstance(configured_api_base, str) else agent_url
+    api_base: Final = configured_api_base if isinstance(configured_api_base, str) and configured_api_base else agent_url
     registered_model: Final = registered_params_value.get("model") if registered_params_value else None
     cardless_provider: Final = registered_provider == "watsonx_orchestrate" or (
         registered_provider == "bedrock" and isinstance(registered_model, str) and "agentcore" in registered_model
diff --git a/litellm/proxy/common_request_processing.py b/litellm/proxy/common_request_processing.py
index 5927214a202..04432b2ca21 100644
--- a/litellm/proxy/common_request_processing.py
+++ b/litellm/proxy/common_request_processing.py
@@ -2544,6 +2544,7 @@ class ProxyBaseLLMRequestProcessing:
             ProxyBaseLLMRequestProcessing._flush_deferred_async_logging(
                 logging_obj=logging_obj,
                 exception_raised=_exception_raised,
+                response=response,
             )
 
             # Streaming cleanup: if an exception occurred AND the deferred
@@ -3027,6 +3028,7 @@ class ProxyBaseLLMRequestProcessing:
     def _flush_deferred_async_logging(
         logging_obj: Any,
         exception_raised: bool,
+        response: Any | None = None,
     ) -> None:
         """
         Fire the deferred async-success closure stored by wrapper_async, then
@@ -3057,7 +3059,7 @@ class ProxyBaseLLMRequestProcessing:
         if exception_raised:
             return
         try:
-            _enqueue_fn()
+            _enqueue_fn(response) if response is not None else _enqueue_fn()
         except Exception as e:
             verbose_proxy_logger.exception("Error firing deferred logging: %s", e)
 
diff --git a/litellm/utils.py b/litellm/utils.py
index e5ce7157e77..fb636b094f1 100644
--- a/litellm/utils.py
+++ b/litellm/utils.py
@@ -1818,11 +1818,11 @@ def client(original_function):
             if not _is_litellm_internal_call:
                 if getattr(logging_obj, "_defer_async_logging", False):
 
-                    def _enqueue_deferred_logging() -> None:
+                    def _enqueue_deferred_logging(final_response=None) -> None:
                         asyncio.create_task(
                             _client_async_logging_helper(
                                 logging_obj=logging_obj,
-                                result=result,
+                                result=final_response if final_response is not None else result,
                                 start_time=start_time,
                                 end_time=end_time,
                                 is_completion_with_fallbacks=is_completion_with_fallbacks,
diff --git a/tests/test_litellm/a2a_protocol/providers/bedrock_agentcore/test_bedrock_agentcore_a2a.py b/tests/test_litellm/a2a_protocol/providers/bedrock_agentcore/test_bedrock_agentcore_a2a.py
index 5503a5668bf..a959386aae9 100644
--- a/tests/test_litellm/a2a_protocol/providers/bedrock_agentcore/test_bedrock_agentcore_a2a.py
+++ b/tests/test_litellm/a2a_protocol/providers/bedrock_agentcore/test_bedrock_agentcore_a2a.py
@@ -10,10 +10,9 @@ Verifies that:
 """
 
 import json
-
-import pytest
 from unittest.mock import AsyncMock, MagicMock, patch
 
+import pytest
 
 SAMPLE_ARN = "arn:aws:bedrock-agentcore:us-west-2:123456789:runtime/my_agent"
 SAMPLE_MODEL = f"bedrock/agentcore/{SAMPLE_ARN}"
@@ -482,6 +481,7 @@ class TestHandlerIntegration:
                 api_base=None,
                 litellm_params=SAMPLE_LITELLM_PARAMS,
                 agent_extra_headers=None,
+                agent_static_headers=None,
             )
 
     @pytest.mark.asyncio
diff --git a/tests/test_litellm/a2a_protocol/test_completion_bridge_streaming.py b/tests/test_litellm/a2a_protocol/test_completion_bridge_streaming.py
index 11f2e75107d..29d4e6ffe36 100644
--- a/tests/test_litellm/a2a_protocol/test_completion_bridge_streaming.py
+++ b/tests/test_litellm/a2a_protocol/test_completion_bridge_streaming.py
@@ -324,10 +324,13 @@ async def test_handle_streaming_preserves_non_text_delta_fields():
         ]
 
     result = events[-1]["result"]
-    assert result["audio"] == {"data": "abc"}
-    assert result["reasoning_content"] == "thinking"
-    assert result["provider_specific_fields"] == {"trace_id": "trace-1"}
-    assert result["logprobs"] == {"content": []}
+    choice_result = result["choices"][0]
+    assert choice_result["delta"] == {
+        "audio": {"data": "abc"},
+        "reasoning_content": "thinking",
+        "provider_specific_fields": {"trace_id": "trace-1"},
+    }
+    assert choice_result["logprobs"] == {"content": []}
 
 
 @pytest.mark.asyncio
diff --git a/tests/test_litellm/proxy/test_route_a2a_models.py b/tests/test_litellm/proxy/test_route_a2a_models.py
index 2a34f4404bc..05bc118907c 100644
--- a/tests/test_litellm/proxy/test_route_a2a_models.py
+++ b/tests/test_litellm/proxy/test_route_a2a_models.py
@@ -62,7 +62,7 @@ async def test_route_a2a_model_bypasses_router():
             "litellm.proxy.agent_endpoints.agent_registry.global_agent_registry",
             mock_registry,
         ):
-            result = await route_request(
+            await route_request(
                 data=data,
                 llm_router=mock_router,
                 user_model=None,
@@ -593,6 +593,7 @@ async def test_route_a2a_stream_uses_registered_provider():
         litellm_params={"custom_llm_provider": "pydantic_ai_agents"},
     )
     logging_obj = Mock(spec=Logging)
+    logging_obj.model_call_details = {}
     data = {
         "model": "a2a/test-agent",
         "messages": [{"role": "user", "content": "Hello"}],
@@ -745,7 +746,7 @@ def _router_without_models():
 
 @pytest.mark.asyncio
 async def test_route_a2a_model_read_through_recovers_agent_created_on_sibling_replica(monkeypatch):
-    import litellm.proxy.proxy_server as proxy_server
+    from litellm.proxy import proxy_server
     from litellm.proxy.agent_endpoints.agent_registry import global_agent_registry
 
     agent_name = "a2a-sibling-replica-agent"