fix(oci): address remaining bugs from issue #25082 — streaming signed body, Cohere stop sequences, hardcoded defaults

- Bug 1: sync and async streaming paths now use signed_json_body when provided
  instead of re-serializing data with json.dumps() — the OCI RSA-SHA256 signature
  covers the exact request body bytes, so re-serializing produces an invalid sig
- Bug 3: Cohere stop sequences now map to 'stopSequences' (was incorrectly 'stop')
- Bug 4: removed hardcoded Cohere defaults (maxTokens=600, temperature=1, topK=0,
  topP=0.75, frequencyPenalty=0) that silently overrode user intent on every call
- Added 6 unit tests covering all three fixes

litellm/llms/oci/chat/transformation.py

@@ -145,10 +145,12 @@ class OCIChatConfig(BaseConfig):
             "response_format": "responseFormat",
         }
 
-        # Cohere uses the same parameter keys as GENERIC except tool_choice is unsupported.
+        # Cohere uses the same parameter keys as GENERIC with two differences:
+        # - tool_choice is unsupported
+        # - stop sequences are named "stopSequences" not "stop"
         # Build a *separate* frozen reference map so callers never mutate the canonical dict.
         self._openai_to_oci_cohere_param_map = {
-            k: v
+            k: ("stopSequences" if k == "stop" else v)
             for k, v in self.openai_to_oci_generic_param_map.items()
             if k not in ("tool_choice", "max_retries")
         }
@@ -281,14 +283,6 @@ class OCIChatConfig(BaseConfig):
         selected_params: Dict = {}
         if vendor == OCIVendors.COHERE:
             open_ai_to_oci_param_map = self._openai_to_oci_cohere_param_map
-            # Add default values for Cohere API
-            selected_params = {
-                "maxTokens": 600,
-                "temperature": 1,
-                "topK": 0,
-                "topP": 0.75,
-                "frequencyPenalty": 0,
-            }
         else:
             open_ai_to_oci_param_map = self.openai_to_oci_generic_param_map
 
@@ -717,7 +711,7 @@ class OCIChatConfig(BaseConfig):
             response = client.post(
                 api_base,
                 headers=headers,
-                data=json.dumps(data),
+                data=signed_json_body if signed_json_body is not None else json.dumps(data),
                 stream=True,
                 logging_obj=logging_obj,
                 timeout=STREAMING_TIMEOUT,
@@ -768,7 +762,7 @@ class OCIChatConfig(BaseConfig):
             response = await client.post(
                 api_base,
                 headers=headers,
-                data=json.dumps(data),
+                data=signed_json_body if signed_json_body is not None else json.dumps(data),
                 stream=True,
                 logging_obj=logging_obj,
                 timeout=STREAMING_TIMEOUT,

tests/test_litellm/llms/oci/chat/test_oci_chat_transformation.py

@@ -885,3 +885,153 @@ class TestOCIProviderEmbeddingConfig:
             f"Expected exactly 1 OCI branch in get_provider_embedding_config, found {oci_count}. "
             "A duplicate dead-code branch may have been reintroduced."
         )
+
+
+class TestOCICohereParamMapping:
+    """
+    Unit tests for Bug 3 (stop → stopSequences) and Bug 4 (hardcoded defaults removed).
+    """
+
+    def _make_config(self):
+        return OCIChatConfig()
+
+    def test_cohere_stop_maps_to_stop_sequences(self):
+        """Bug 3: Cohere API uses 'stopSequences', not 'stop'."""
+        config = self._make_config()
+        result = config.map_openai_params(
+            non_default_params={"stop": ["END", "STOP"]},
+            optional_params={},
+            model="cohere.command-latest",
+            drop_params=False,
+        )
+        assert "stopSequences" in result, "stop should map to stopSequences for Cohere"
+        assert result["stopSequences"] == ["END", "STOP"]
+        assert "stop" not in result
+
+    def test_generic_stop_maps_to_stop(self):
+        """GENERIC vendors (Meta, Google, xAI) keep 'stop' as-is."""
+        config = self._make_config()
+        result = config.map_openai_params(
+            non_default_params={"stop": ["END"]},
+            optional_params={},
+            model="meta.llama-3.3-70b-instruct",
+            drop_params=False,
+        )
+        assert result.get("stop") == ["END"]
+        assert "stopSequences" not in result
+
+    def test_cohere_no_hardcoded_defaults(self):
+        """Bug 4: Cohere calls must not inject maxTokens/temperature/topK/topP/frequencyPenalty
+        when the user hasn't provided them."""
+        config = self._make_config()
+        result = config.map_openai_params(
+            non_default_params={},
+            optional_params={},
+            model="cohere.command-latest",
+            drop_params=False,
+        )
+        for injected in ("maxTokens", "temperature", "topK", "topP", "frequencyPenalty"):
+            assert injected not in result, (
+                f"'{injected}' should not be injected when user did not provide it"
+            )
+
+    def test_cohere_explicit_params_still_passed(self):
+        """User-provided Cohere params must still be forwarded correctly."""
+        config = self._make_config()
+        result = config.map_openai_params(
+            non_default_params={"max_tokens": 200, "temperature": 0.5},
+            optional_params={},
+            model="cohere.command-latest",
+            drop_params=False,
+        )
+        assert result.get("maxTokens") == 200
+        assert result.get("temperature") == 0.5
+
+
+class TestOCIStreamingSignedBody:
+    """
+    Unit test for Bug 1: sync and async streaming paths must use signed_json_body
+    when provided, not re-serialize data with json.dumps().
+    """
+
+    def test_get_custom_stream_wrapper_uses_signed_body(self, monkeypatch):
+        """
+        When signed_json_body is provided, the POST must use that exact bytes object,
+        not json.dumps(data) — otherwise the RSA-SHA256 signature is invalid.
+        """
+        import httpx
+        from unittest.mock import MagicMock, patch
+
+        config = OCIChatConfig()
+        signed_bytes = b'{"signed": true}'
+        posted_data = {}
+
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_response.iter_text.return_value = iter([])
+
+        mock_client = MagicMock()
+        mock_client.post.return_value = mock_response
+
+        def capture_post(url, **kwargs):
+            posted_data["data"] = kwargs.get("data")
+            return mock_response
+
+        mock_client.post.side_effect = capture_post
+
+        mock_logging = MagicMock()
+
+        config.get_sync_custom_stream_wrapper(
+            api_base="https://example.com",
+            headers={},
+            data={"key": "value"},
+            messages=[],
+            model="meta.llama-3.3-70b-instruct",
+            custom_llm_provider="oci",
+            logging_obj=mock_logging,
+            client=mock_client,
+            signed_json_body=signed_bytes,
+        )
+
+        assert posted_data["data"] == signed_bytes, (
+            "Streaming must use signed_json_body, not re-serialize data"
+        )
+
+    def test_get_custom_stream_wrapper_fallback_without_signed_body(self, monkeypatch):
+        """When signed_json_body is None, fall back to json.dumps(data)."""
+        import json
+        from unittest.mock import MagicMock
+
+        config = OCIChatConfig()
+        posted_data = {}
+
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_response.iter_text.return_value = iter([])
+
+        mock_client = MagicMock()
+
+        def capture_post(url, **kwargs):
+            posted_data["data"] = kwargs.get("data")
+            return mock_response
+
+        mock_client.post.side_effect = capture_post
+
+        mock_logging = MagicMock()
+        payload = {"key": "value"}
+
+        config.get_sync_custom_stream_wrapper(
+            api_base="https://example.com",
+            headers={},
+            data=payload,
+            messages=[],
+            model="meta.llama-3.3-70b-instruct",
+            custom_llm_provider="oci",
+            logging_obj=mock_logging,
+            client=mock_client,
+            signed_json_body=None,
+        )
+
+        assert posted_data["data"] == json.dumps(payload), (
+            "Without signed_json_body, must fall back to json.dumps(data)"
+        )