From e9a40ad4d2d6712812e9b9210b28d4c291cdfc0b Mon Sep 17 00:00:00 2001
From: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
Date: Fri, 4 Sep 2026 22:16:14 -0700
Subject: [PATCH] fix(fireworks_ai): map developer items after pydantic input
 items are dumped

---
 .../fireworks_ai/responses/transformation.py  |  5 ++-
 ...t_fireworks_ai_responses_transformation.py | 43 ++++++++++++++++++-
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/litellm/llms/fireworks_ai/responses/transformation.py b/litellm/llms/fireworks_ai/responses/transformation.py
index 121d3b5d9a9..fb0587553d4 100644
--- a/litellm/llms/fireworks_ai/responses/transformation.py
+++ b/litellm/llms/fireworks_ai/responses/transformation.py
@@ -68,6 +68,9 @@ class FireworksAIResponsesAPIConfig(OpenAIResponsesAPIConfig):
         base: Final = (api_base or get_secret_str("FIREWORKS_API_BASE") or FIREWORKS_AI_DEFAULT_API_BASE).rstrip("/")
         return f"{base}/responses"
 
+    def _validate_input_param(self, input: str | ResponseInputParam) -> str | ResponseInputParam:
+        return _developer_items_as_system(super()._validate_input_param(input))
+
     def transform_responses_api_request(
         self,
         model: str,
@@ -78,7 +81,7 @@ class FireworksAIResponsesAPIConfig(OpenAIResponsesAPIConfig):
     ) -> dict:  # mutable-ok: overrides the base class signature
         return super().transform_responses_api_request(
             model=resolve_fireworks_resource_name(model),
-            input=_developer_items_as_system(input),
+            input=input,
             response_api_optional_request_params=response_api_optional_request_params,
             litellm_params=litellm_params,
             headers=headers,
diff --git a/tests/test_litellm/llms/fireworks_ai/responses/test_fireworks_ai_responses_transformation.py b/tests/test_litellm/llms/fireworks_ai/responses/test_fireworks_ai_responses_transformation.py
index f948acb7bf3..b9408d44e9a 100644
--- a/tests/test_litellm/llms/fireworks_ai/responses/test_fireworks_ai_responses_transformation.py
+++ b/tests/test_litellm/llms/fireworks_ai/responses/test_fireworks_ai_responses_transformation.py
@@ -1,13 +1,14 @@
 import json
 from collections.abc import Mapping
 from types import MappingProxyType
-from typing import Final, TypedDict
+from typing import Final, TypedDict, cast
 from unittest.mock import MagicMock, patch
 from urllib.parse import quote
 
 import httpx
 import pytest
 from openai.types.responses import (
+    EasyInputMessage,
     ResponseFunctionToolCall,
     ResponseOutputMessage,
     ResponseOutputText,
@@ -20,7 +21,7 @@ from typing_extensions import ReadOnly
 import litellm
 from litellm.llms.fireworks_ai.responses.transformation import FireworksAIResponsesAPIConfig
 from litellm.responses.file_search.emulated_handler import should_use_emulated_file_search
-from litellm.types.llms.openai import InputTokensDetails, ResponseAPIUsage, ResponsesAPIResponse
+from litellm.types.llms.openai import InputTokensDetails, ResponseAPIUsage, ResponseInputParam, ResponsesAPIResponse
 from litellm.types.router import GenericLiteLLMParams
 from litellm.types.utils import LlmProviders
 from litellm.utils import ProviderConfigManager
@@ -181,6 +182,44 @@ def test_responses_call_sends_developer_items_as_system_messages() -> None:
     )
 
 
+def test_responses_call_maps_pydantic_developer_items_and_replays_pydantic_output_items() -> None:
+    client: Final = _mock_http_client(_fireworks_response("accounts/fireworks/models/kimi-k3"))
+    pydantic_input: Final = cast(
+        ResponseInputParam,
+        [  # mutable-ok: the Responses API takes input as a JSON list
+            EasyInputMessage(role="developer", content="Answer with exactly one word.", type="message"),
+            ResponseReasoningItem(id="rs_1", summary=(), type="reasoning"),
+            ResponseFunctionToolCall(
+                id="fc_1",
+                call_id="call_abc123",
+                name="get_weather",
+                arguments='{"city": "Paris"}',
+                status="completed",
+                type="function_call",
+            ),
+            FunctionCallOutput(type="function_call_output", call_id="call_abc123", output="21C"),
+        ],
+    )
+    with patch(HTTPX_CLIENT_FACTORY, return_value=client):
+        litellm.responses(
+            model="fireworks_ai/accounts/fireworks/models/kimi-k3", input=pydantic_input, api_key="fw-test-key"
+        )
+    _, _, body = _sent_request(client)
+    assert tuple(body["input"]) == (
+        {"role": "system", "content": "Answer with exactly one word.", "type": "message"},
+        {"id": "rs_1", "summary": [], "type": "reasoning"},
+        {
+            "id": "fc_1",
+            "call_id": "call_abc123",
+            "name": "get_weather",
+            "arguments": '{"city": "Paris"}',
+            "status": "completed",
+            "type": "function_call",
+        },
+        {"type": "function_call_output", "call_id": "call_abc123", "output": "21C"},
+    )
+
+
 def test_file_search_tools_take_litellm_emulated_search_not_fireworks() -> None:
     config: Final = FireworksAIResponsesAPIConfig()
     file_search: Final = ({"type": "file_search", "vector_store_ids": ("vs_kb",)},)