test: cover fireworks tool-call payload sanitization

tests/test_provider_parity.py

@@ -168,6 +168,52 @@ class TestBuildApiKwargsCustomEndpoint:
         extra = kwargs.get("extra_body", {})
         assert "reasoning" not in extra
 
+    def test_fireworks_tool_call_payload_strips_codex_only_fields(self, monkeypatch):
+        agent = _make_agent(
+            monkeypatch,
+            "custom",
+            base_url="https://api.fireworks.ai/inference/v1",
+        )
+        messages = [
+            {"role": "user", "content": "hi"},
+            {
+                "role": "assistant",
+                "content": "Checking now.",
+                "codex_reasoning_items": [
+                    {"type": "reasoning", "id": "rs_1", "encrypted_content": "blob"},
+                ],
+                "tool_calls": [
+                    {
+                        "id": "call_fw_123",
+                        "call_id": "call_fw_123",
+                        "response_item_id": "fc_fw_123",
+                        "type": "function",
+                        "function": {
+                            "name": "terminal",
+                            "arguments": "{\"command\":\"pwd\"}",
+                        },
+                    }
+                ],
+            },
+            {"role": "tool", "tool_call_id": "call_fw_123", "content": "/tmp"},
+        ]
+
+        kwargs = agent._build_api_kwargs(messages)
+
+        assert kwargs["tools"][0]["function"]["name"] == "web_search"
+        assert "input" not in kwargs
+        assert kwargs.get("extra_body", {}) == {}
+
+        assistant_msg = kwargs["messages"][1]
+        tool_call = assistant_msg["tool_calls"][0]
+
+        assert "codex_reasoning_items" not in assistant_msg
+        assert tool_call["id"] == "call_fw_123"
+        assert tool_call["type"] == "function"
+        assert tool_call["function"]["name"] == "terminal"
+        assert "call_id" not in tool_call
+        assert "response_item_id" not in tool_call
+
 
 class TestBuildApiKwargsCodex:
     def test_uses_responses_api_format(self, monkeypatch):