diff --git a/tests/test_litellm/llms/oci/test_oci_coverage_boost.py b/tests/test_litellm/llms/oci/test_oci_coverage_boost.py
new file mode 100644
index 00000000000..c75d9baab1c
--- /dev/null
+++ b/tests/test_litellm/llms/oci/test_oci_coverage_boost.py
@@ -0,0 +1,960 @@
+"""
+Coverage-boost tests for the OCI provider happy paths.
+
+Covers:
+  - litellm/llms/oci/common_utils.py  (sign_with_manual_credentials, routing)
+  - litellm/llms/oci/chat/generic.py  (message adaptation, tool conversion, streaming)
+  - litellm/llms/oci/chat/cohere.py   (message adaptation, response parsing, streaming)
+  - litellm/llms/oci/chat/transformation.py  (OCIChatConfig methods, stream wrappers)
+
+All tests are self-contained and require no real OCI credentials or network access.
+"""
+
+import json
+import pytest
+from unittest.mock import patch, MagicMock, AsyncMock
+
+import httpx
+
+from litellm import ModelResponse
+from litellm.llms.oci.chat.cohere import (
+    _extract_text_content,
+    adapt_messages_to_cohere_standard,
+    handle_cohere_response,
+    handle_cohere_stream_chunk,
+)
+from litellm.llms.oci.chat.generic import (
+    adapt_messages_to_generic_oci_standard,
+    adapt_messages_to_generic_oci_standard_tool_response,
+    adapt_tool_definition_to_oci_standard,
+    adapt_tools_to_openai_standard,
+    handle_generic_stream_chunk,
+)
+from litellm.llms.oci.chat.transformation import OCIChatConfig, get_vendor_from_model
+from litellm.llms.oci.common_utils import (
+    OCIError,
+    sign_with_manual_credentials,
+    sign_oci_request,
+    validate_oci_environment,
+)
+from litellm.types.llms.oci import OCIVendors, OCIToolCall
+
+
+# ---------------------------------------------------------------------------
+# Helpers / fixtures
+# ---------------------------------------------------------------------------
+
+_MANUAL_CREDS = {
+    "oci_user": "ocid1.user.oc1..xxx",
+    "oci_fingerprint": "aa:bb:cc:dd",
+    "oci_tenancy": "ocid1.tenancy.oc1..xxx",
+    "oci_compartment_id": "ocid1.compartment.oc1..xxx",
+    "oci_key": "-----BEGIN RSA PRIVATE KEY-----\nfake\n-----END RSA PRIVATE KEY-----",
+}
+
+_API_BASE = "https://inference.generativeai.us-ashburn-1.oci.oraclecloud.com/20231130/actions/chat"
+
+_COHERE_MODEL = "cohere.command-r-plus"
+_GENERIC_MODEL = "meta.llama-3-70b-instruct"
+
+
+# ===========================================================================
+# common_utils.py — sign_with_manual_credentials happy paths
+# ===========================================================================
+
+
+@patch("litellm.llms.oci.common_utils._CRYPTOGRAPHY_AVAILABLE", True)
+@patch("litellm.llms.oci.common_utils.load_private_key_from_str")
+@patch("litellm.llms.oci.common_utils.padding")
+@patch("litellm.llms.oci.common_utils.hashes")
+def test_sign_with_manual_credentials_inline_key(mock_hashes, mock_padding, mock_load_key):
+    """sign_with_manual_credentials succeeds with an inline oci_key string."""
+    mock_key = MagicMock()
+    mock_key.sign.return_value = b"fake_signature"
+    mock_load_key.return_value = mock_key
+
+    result_headers, body = sign_with_manual_credentials(
+        {}, _MANUAL_CREDS, {"key": "val"}, _API_BASE
+    )
+
+    assert "authorization" in result_headers
+    assert result_headers["authorization"].startswith('Signature version="1"')
+    assert "rsa-sha256" in result_headers["authorization"]
+    assert isinstance(body, bytes)
+    mock_key.sign.assert_called_once()
+
+
+@patch("litellm.llms.oci.common_utils._CRYPTOGRAPHY_AVAILABLE", True)
+@patch("litellm.llms.oci.common_utils.load_private_key_from_file")
+@patch("litellm.llms.oci.common_utils.padding")
+@patch("litellm.llms.oci.common_utils.hashes")
+def test_sign_with_manual_credentials_key_file(mock_hashes, mock_padding, mock_load_file):
+    """sign_with_manual_credentials falls back to oci_key_file when oci_key absent."""
+    mock_key = MagicMock()
+    mock_key.sign.return_value = b"sig_from_file"
+    mock_load_file.return_value = mock_key
+
+    creds = {**_MANUAL_CREDS, "oci_key_file": "/tmp/key.pem"}
+    creds_no_inline = {k: v for k, v in creds.items() if k != "oci_key"}
+
+    result_headers, body = sign_with_manual_credentials(
+        {}, creds_no_inline, {}, _API_BASE
+    )
+
+    assert "authorization" in result_headers
+    mock_load_file.assert_called_once_with("/tmp/key.pem")
+
+
+@patch("litellm.llms.oci.common_utils._CRYPTOGRAPHY_AVAILABLE", True)
+@patch("litellm.llms.oci.common_utils.load_private_key_from_str")
+@patch("litellm.llms.oci.common_utils.padding")
+@patch("litellm.llms.oci.common_utils.hashes")
+def test_sign_with_manual_credentials_authorization_contains_key_id(
+    mock_hashes, mock_padding, mock_load_key
+):
+    """Authorization header encodes tenancy/user/fingerprint as key ID."""
+    mock_key = MagicMock()
+    mock_key.sign.return_value = b"sig"
+    mock_load_key.return_value = mock_key
+
+    result_headers, _ = sign_with_manual_credentials(
+        {}, _MANUAL_CREDS, {}, _API_BASE
+    )
+
+    auth = result_headers["authorization"]
+    assert 'keyId="ocid1.tenancy.oc1..xxx/ocid1.user.oc1..xxx/aa:bb:cc:dd"' in auth
+
+
+def test_sign_with_manual_credentials_non_string_oci_key_raises():
+    """Passing a non-string oci_key raises OCIError(400)."""
+    bad_creds = {**_MANUAL_CREDS, "oci_key": 12345}
+    with pytest.raises(OCIError) as exc_info:
+        sign_with_manual_credentials({}, bad_creds, {}, _API_BASE)
+    assert exc_info.value.status_code == 400
+    assert "oci_key must be a string" in str(exc_info.value)
+
+
+# ---------------------------------------------------------------------------
+# common_utils.py — sign_oci_request routing
+# ---------------------------------------------------------------------------
+
+
+def test_sign_oci_request_routes_to_signer_when_present():
+    """sign_oci_request delegates to sign_with_oci_signer when oci_signer is set."""
+    signer = MagicMock()
+    signer.do_request_sign.return_value = None
+    headers, body = sign_oci_request(
+        {}, {"oci_signer": signer}, {"data": 1}, _API_BASE
+    )
+    signer.do_request_sign.assert_called_once()
+    assert isinstance(body, bytes)
+
+
+@patch("litellm.llms.oci.common_utils._CRYPTOGRAPHY_AVAILABLE", True)
+@patch("litellm.llms.oci.common_utils.load_private_key_from_str")
+@patch("litellm.llms.oci.common_utils.padding")
+@patch("litellm.llms.oci.common_utils.hashes")
+def test_sign_oci_request_routes_to_manual_when_no_signer(
+    mock_hashes, mock_padding, mock_load_key
+):
+    """sign_oci_request delegates to sign_with_manual_credentials when oci_signer absent."""
+    mock_key = MagicMock()
+    mock_key.sign.return_value = b"sig"
+    mock_load_key.return_value = mock_key
+
+    headers, body = sign_oci_request({}, _MANUAL_CREDS, {}, _API_BASE)
+    assert "authorization" in headers
+
+
+# ---------------------------------------------------------------------------
+# common_utils.py — _require_cryptography happy path
+# ---------------------------------------------------------------------------
+
+
+def test_require_cryptography_available_does_not_raise():
+    """_require_cryptography() should not raise when the package is importable."""
+    from litellm.llms.oci.common_utils import _require_cryptography
+
+    with patch("litellm.llms.oci.common_utils._CRYPTOGRAPHY_AVAILABLE", True):
+        _require_cryptography()  # must not raise
+
+
+# ===========================================================================
+# generic.py — adapt_messages_to_generic_oci_standard
+# ===========================================================================
+
+
+def test_adapt_generic_user_message_string_content():
+    messages = [{"role": "user", "content": "Hello!"}]
+    result = adapt_messages_to_generic_oci_standard(messages)
+    assert len(result) == 1
+    assert result[0].role == "USER"
+    assert result[0].content[0].text == "Hello!"
+
+
+def test_adapt_generic_assistant_message():
+    messages = [{"role": "assistant", "content": "Hi there!"}]
+    result = adapt_messages_to_generic_oci_standard(messages)
+    assert result[0].role == "ASSISTANT"
+    assert result[0].content[0].text == "Hi there!"
+
+
+def test_adapt_generic_system_message():
+    messages = [{"role": "system", "content": "You are a helpful assistant."}]
+    result = adapt_messages_to_generic_oci_standard(messages)
+    assert result[0].role == "SYSTEM"
+    assert result[0].content[0].text == "You are a helpful assistant."
+
+
+def test_adapt_generic_tool_message():
+    messages = [
+        {
+            "role": "tool",
+            "tool_call_id": "call_abc123",
+            "content": "42 degrees",
+        }
+    ]
+    result = adapt_messages_to_generic_oci_standard(messages)
+    assert result[0].role == "TOOL"
+    assert result[0].toolCallId == "call_abc123"
+    assert result[0].content[0].text == "42 degrees"
+
+
+def test_adapt_generic_assistant_tool_call_message():
+    messages = [
+        {
+            "role": "assistant",
+            "content": None,
+            "tool_calls": [
+                {
+                    "id": "call_xyz",
+                    "type": "function",
+                    "function": {"name": "get_weather", "arguments": '{"city": "Rome"}'},
+                }
+            ],
+        }
+    ]
+    result = adapt_messages_to_generic_oci_standard(messages)
+    assert result[0].role == "ASSISTANT"
+    assert result[0].toolCalls is not None
+    assert len(result[0].toolCalls) == 1
+    tc = result[0].toolCalls[0]
+    assert tc.name == "get_weather"
+    assert tc.arguments == '{"city": "Rome"}'
+
+
+def test_adapt_generic_multipart_content():
+    messages = [
+        {
+            "role": "user",
+            "content": [
+                {"type": "text", "text": "Look at this:"},
+                {"type": "image_url", "image_url": {"url": "https://example.com/img.png"}},
+            ],
+        }
+    ]
+    result = adapt_messages_to_generic_oci_standard(messages)
+    assert len(result[0].content) == 2
+    assert result[0].content[0].text == "Look at this:"
+    assert result[0].content[1].imageUrl.url == "https://example.com/img.png"
+
+
+# ---------------------------------------------------------------------------
+# generic.py — adapt_messages_to_generic_oci_standard_tool_response
+# ---------------------------------------------------------------------------
+
+
+def test_adapt_generic_tool_response_direct():
+    result = adapt_messages_to_generic_oci_standard_tool_response(
+        "tool", "call_999", "The answer is 42"
+    )
+    assert result.role == "TOOL"
+    assert result.toolCallId == "call_999"
+    assert result.content[0].text == "The answer is 42"
+
+
+# ---------------------------------------------------------------------------
+# generic.py — adapt_tool_definition_to_oci_standard
+# ---------------------------------------------------------------------------
+
+
+def test_adapt_tool_definition_basic():
+    tools = [
+        {
+            "type": "function",
+            "function": {
+                "name": "get_weather",
+                "description": "Retrieve current weather",
+                "parameters": {
+                    "type": "object",
+                    "properties": {"city": {"type": "string"}},
+                    "required": ["city"],
+                },
+            },
+        }
+    ]
+    result = adapt_tool_definition_to_oci_standard(tools, OCIVendors.GENERIC)
+    assert len(result) == 1
+    tool_def = result[0]
+    assert tool_def.name == "get_weather"
+    assert tool_def.type == "FUNCTION"
+    assert tool_def.parameters is not None
+
+
+def test_adapt_tool_definition_resolves_refs():
+    """$ref/$defs schemas are inlined before being sent to OCI."""
+    tools = [
+        {
+            "type": "function",
+            "function": {
+                "name": "do_thing",
+                "parameters": {
+                    "$defs": {"Loc": {"type": "string"}},
+                    "type": "object",
+                    "properties": {"location": {"$ref": "#/$defs/Loc"}},
+                },
+            },
+        }
+    ]
+    result = adapt_tool_definition_to_oci_standard(tools, OCIVendors.GENERIC)
+    props = result[0].parameters["properties"]
+    assert props["location"] == {"type": "string"}
+
+
+# ---------------------------------------------------------------------------
+# generic.py — adapt_tools_to_openai_standard
+# ---------------------------------------------------------------------------
+
+
+def test_adapt_tools_to_openai_standard():
+    oci_tool = OCIToolCall(
+        id="call_abc",
+        type="FUNCTION",
+        name="search",
+        arguments='{"query": "hello"}',
+    )
+    result = adapt_tools_to_openai_standard([oci_tool])
+    assert len(result) == 1
+    assert result[0].id == "call_abc"
+    assert result[0].type == "function"
+    assert result[0].function["name"] == "search"
+
+
+def test_adapt_tools_to_openai_standard_generates_id_when_absent():
+    oci_tool = OCIToolCall(
+        id=None,
+        type="FUNCTION",
+        name="lookup",
+        arguments="{}",
+    )
+    result = adapt_tools_to_openai_standard([oci_tool])
+    assert result[0].id.startswith("call_")
+
+
+# ---------------------------------------------------------------------------
+# generic.py — handle_generic_stream_chunk
+# ---------------------------------------------------------------------------
+
+
+def test_handle_generic_stream_chunk_text_content():
+    chunk = {
+        "message": {
+            "content": [{"type": "TEXT", "text": "Hello from OCI"}],
+            "role": "ASSISTANT",
+        },
+        "finishReason": None,
+        "index": 0,
+    }
+    result = handle_generic_stream_chunk(chunk)
+    assert result.choices[0].delta.content == "Hello from OCI"
+    assert result.choices[0].finish_reason is None
+
+
+def test_handle_generic_stream_chunk_complete_finish_reason():
+    chunk = {"finishReason": "COMPLETE", "index": 0}
+    result = handle_generic_stream_chunk(chunk)
+    assert result.choices[0].finish_reason == "stop"
+
+
+def test_handle_generic_stream_chunk_max_tokens_finish_reason():
+    chunk = {"finishReason": "MAX_TOKENS", "index": 0}
+    result = handle_generic_stream_chunk(chunk)
+    assert result.choices[0].finish_reason == "length"
+
+
+def test_handle_generic_stream_chunk_tool_calls_finish_reason():
+    chunk = {"finishReason": "TOOL_CALLS", "index": 0}
+    result = handle_generic_stream_chunk(chunk)
+    assert result.choices[0].finish_reason == "tool_calls"
+
+
+def test_handle_generic_stream_chunk_no_message():
+    """Chunks without a message key should still parse without error."""
+    chunk = {"finishReason": "COMPLETE", "index": 1}
+    result = handle_generic_stream_chunk(chunk)
+    assert result.choices[0].delta.content == ""
+    assert result.choices[0].finish_reason == "stop"
+
+
+# ===========================================================================
+# cohere.py — _extract_text_content
+# ===========================================================================
+
+
+def test_extract_text_content_none():
+    assert _extract_text_content(None) == ""
+
+
+def test_extract_text_content_string():
+    assert _extract_text_content("hello") == "hello"
+
+
+def test_extract_text_content_list():
+    content = [
+        {"type": "text", "text": "foo"},
+        {"type": "text", "text": "bar"},
+    ]
+    assert _extract_text_content(content) == "foobar"
+
+
+def test_extract_text_content_list_skips_non_text():
+    content = [
+        {"type": "image_url", "url": "https://x.com/img.png"},
+        {"type": "text", "text": "only this"},
+    ]
+    assert _extract_text_content(content) == "only this"
+
+
+def test_extract_text_content_non_string_non_list():
+    assert _extract_text_content(42) == "42"
+
+
+# ===========================================================================
+# cohere.py — adapt_messages_to_cohere_standard
+# ===========================================================================
+
+
+def test_adapt_cohere_user_in_history():
+    messages = [
+        {"role": "user", "content": "first question"},
+        {"role": "user", "content": "current question"},
+    ]
+    history = adapt_messages_to_cohere_standard(messages)
+    assert len(history) == 1
+    assert history[0].role == "USER"
+    assert history[0].message == "first question"
+
+
+def test_adapt_cohere_assistant_in_history():
+    messages = [
+        {"role": "user", "content": "q"},
+        {"role": "assistant", "content": "answer"},
+        {"role": "user", "content": "follow-up"},
+    ]
+    history = adapt_messages_to_cohere_standard(messages)
+    assert len(history) == 2
+    chatbot_msg = history[1]
+    assert chatbot_msg.role == "CHATBOT"
+    assert chatbot_msg.message == "answer"
+
+
+def test_adapt_cohere_assistant_with_tool_calls_in_history():
+    messages = [
+        {
+            "role": "assistant",
+            "content": None,
+            "tool_calls": [
+                {
+                    "id": "call_1",
+                    "type": "function",
+                    "function": {"name": "calc", "arguments": '{"x": 1}'},
+                }
+            ],
+        },
+        {"role": "user", "content": "thanks"},
+    ]
+    history = adapt_messages_to_cohere_standard(messages)
+    assert len(history) == 1
+    assert history[0].role == "CHATBOT"
+    assert history[0].toolCalls is not None
+    assert history[0].toolCalls[0].name == "calc"
+
+
+def test_adapt_cohere_tool_result_in_history():
+    messages = [
+        {
+            "role": "assistant",
+            "content": None,
+            "tool_calls": [
+                {
+                    "id": "call_1",
+                    "type": "function",
+                    "function": {"name": "calc", "arguments": '{"x": 1}'},
+                }
+            ],
+        },
+        {
+            "role": "tool",
+            "tool_call_id": "call_1",
+            "content": "result: 42",
+        },
+        {"role": "user", "content": "ok"},
+    ]
+    history = adapt_messages_to_cohere_standard(messages)
+    tool_msg = next(m for m in history if m.role == "TOOL")
+    assert tool_msg.toolResults[0].call.name == "calc"
+    assert tool_msg.toolResults[0].outputs[0]["output"] == "result: 42"
+
+
+# ===========================================================================
+# cohere.py — handle_cohere_response
+# ===========================================================================
+
+
+_COHERE_RESPONSE_JSON = {
+    "modelId": "cohere.command-r-plus",
+    "modelVersion": "1.0",
+    "chatResponse": {
+        "apiFormat": "COHERE",
+        "text": "Hello from Cohere!",
+        "finishReason": "COMPLETE",
+        "usage": {
+            "promptTokens": 10,
+            "completionTokens": 5,
+            "totalTokens": 15,
+        },
+    },
+}
+
+
+def test_handle_cohere_response_complete():
+    model_response = ModelResponse()
+    result = handle_cohere_response(
+        _COHERE_RESPONSE_JSON, _COHERE_MODEL, model_response
+    )
+    assert result.choices[0].finish_reason == "stop"
+    assert result.choices[0].message["content"] == "Hello from Cohere!"
+    assert result.usage.prompt_tokens == 10
+
+
+def test_handle_cohere_response_max_tokens():
+    resp = {
+        **_COHERE_RESPONSE_JSON,
+        "chatResponse": {
+            **_COHERE_RESPONSE_JSON["chatResponse"],
+            "finishReason": "MAX_TOKENS",
+        },
+    }
+    model_response = ModelResponse()
+    result = handle_cohere_response(resp, _COHERE_MODEL, model_response)
+    assert result.choices[0].finish_reason == "length"
+
+
+def test_handle_cohere_response_tool_call():
+    resp = {
+        **_COHERE_RESPONSE_JSON,
+        "chatResponse": {
+            **_COHERE_RESPONSE_JSON["chatResponse"],
+            "finishReason": "TOOL_CALL",
+            "toolCalls": [{"name": "get_time", "parameters": {"tz": "UTC"}}],
+        },
+    }
+    model_response = ModelResponse()
+    result = handle_cohere_response(resp, _COHERE_MODEL, model_response)
+    assert result.choices[0].finish_reason == "tool_calls"
+    tool_calls = result.choices[0].message["tool_calls"]
+    assert tool_calls is not None
+    assert tool_calls[0]["function"]["name"] == "get_time"
+
+
+# ===========================================================================
+# cohere.py — handle_cohere_stream_chunk
+# ===========================================================================
+
+
+def test_handle_cohere_stream_chunk_text():
+    chunk = {"apiFormat": "COHERE", "text": "streaming text", "finishReason": None}
+    result = handle_cohere_stream_chunk(chunk)
+    assert result.choices[0].delta.content == "streaming text"
+    assert result.choices[0].finish_reason is None
+
+
+def test_handle_cohere_stream_chunk_complete():
+    chunk = {"apiFormat": "COHERE", "text": "", "finishReason": "COMPLETE"}
+    result = handle_cohere_stream_chunk(chunk)
+    assert result.choices[0].finish_reason == "stop"
+
+
+def test_handle_cohere_stream_chunk_max_tokens():
+    chunk = {"apiFormat": "COHERE", "text": "", "finishReason": "MAX_TOKENS"}
+    result = handle_cohere_stream_chunk(chunk)
+    assert result.choices[0].finish_reason == "length"
+
+
+def test_handle_cohere_stream_chunk_tool_call():
+    chunk = {"apiFormat": "COHERE", "text": "", "finishReason": "TOOL_CALL"}
+    result = handle_cohere_stream_chunk(chunk)
+    assert result.choices[0].finish_reason == "tool_calls"
+
+
+# ===========================================================================
+# transformation.py — get_vendor_from_model
+# ===========================================================================
+
+
+def test_get_vendor_cohere():
+    assert get_vendor_from_model("cohere.command-r-plus") == OCIVendors.COHERE
+
+
+def test_get_vendor_generic_llama():
+    assert get_vendor_from_model("meta.llama-3-70b-instruct") == OCIVendors.GENERIC
+
+
+def test_get_vendor_generic_xai():
+    assert get_vendor_from_model("xai.grok-4") == OCIVendors.GENERIC
+
+
+def test_get_vendor_generic_google():
+    assert get_vendor_from_model("google.gemini-2-flash") == OCIVendors.GENERIC
+
+
+# ===========================================================================
+# transformation.py — OCIChatConfig methods
+# ===========================================================================
+
+
+class TestOCIChatConfigGetCompleteUrl:
+    def test_returns_chat_endpoint_from_region(self):
+        config = OCIChatConfig()
+        url = config.get_complete_url(
+            api_base=None,
+            api_key=None,
+            model=_GENERIC_MODEL,
+            optional_params={"oci_region": "eu-frankfurt-1"},
+            litellm_params={},
+        )
+        assert url == (
+            "https://inference.generativeai.eu-frankfurt-1.oci.oraclecloud.com"
+            "/20231130/actions/chat"
+        )
+
+    def test_respects_explicit_api_base(self):
+        config = OCIChatConfig()
+        url = config.get_complete_url(
+            api_base="https://custom.endpoint.com/",
+            api_key=None,
+            model=_GENERIC_MODEL,
+            optional_params={},
+            litellm_params={},
+        )
+        assert url == "https://custom.endpoint.com/20231130/actions/chat"
+
+
+class TestOCIChatConfigGetErrorClass:
+    def test_returns_oci_error(self):
+        config = OCIChatConfig()
+        err = config.get_error_class("boom", 503, {})
+        assert isinstance(err, OCIError)
+        assert err.status_code == 503
+
+
+class TestOCIChatConfigSignRequest:
+    @patch("litellm.llms.oci.common_utils._CRYPTOGRAPHY_AVAILABLE", True)
+    @patch("litellm.llms.oci.common_utils.load_private_key_from_str")
+    @patch("litellm.llms.oci.common_utils.padding")
+    @patch("litellm.llms.oci.common_utils.hashes")
+    def test_sign_request_delegates(self, mock_hashes, mock_padding, mock_load_key):
+        mock_key = MagicMock()
+        mock_key.sign.return_value = b"sig"
+        mock_load_key.return_value = mock_key
+
+        config = OCIChatConfig()
+        headers, body = config.sign_request(
+            headers={},
+            optional_params=_MANUAL_CREDS,
+            request_data={"hello": "world"},
+            api_base=_API_BASE,
+        )
+        assert "authorization" in headers
+        assert isinstance(body, bytes)
+
+
+class TestOCIChatConfigValidateEnvironment:
+    def test_with_signer_skips_credential_check(self):
+        """If oci_signer is provided, validate_environment must NOT raise."""
+        config = OCIChatConfig()
+        signer = MagicMock()
+        result = config.validate_environment(
+            headers={},
+            model=_GENERIC_MODEL,
+            messages=[{"role": "user", "content": "hi"}],
+            optional_params={"oci_signer": signer},
+            litellm_params={},
+        )
+        assert result["content-type"] == "application/json"
+
+    def test_raises_when_messages_empty(self):
+        config = OCIChatConfig()
+        with pytest.raises(OCIError) as exc_info:
+            config.validate_environment(
+                headers={},
+                model=_GENERIC_MODEL,
+                messages=[],
+                optional_params={"oci_signer": MagicMock()},
+                litellm_params={},
+            )
+        assert exc_info.value.status_code == 400
+
+
+class TestOCIChatConfigGetOptionalParams:
+    def _config(self):
+        return OCIChatConfig()
+
+    def test_cohere_maps_stop_to_stop_sequences(self):
+        config = self._config()
+        result = config._get_optional_params(
+            OCIVendors.COHERE, {"stop": ["END"]}
+        )
+        assert "stopSequences" in result
+        assert result["stopSequences"] == ["END"]
+
+    def test_generic_maps_max_tokens(self):
+        config = self._config()
+        result = config._get_optional_params(
+            OCIVendors.GENERIC, {"max_tokens": 512}
+        )
+        assert result["maxTokens"] == 512
+
+    def test_tool_choice_string_auto_converted_to_dict(self):
+        config = self._config()
+        result = config._get_optional_params(
+            OCIVendors.GENERIC, {"tool_choice": "auto"}
+        )
+        assert result["toolChoice"] == {"type": "AUTO"}
+
+    def test_tool_choice_string_none_converted_to_dict(self):
+        config = self._config()
+        result = config._get_optional_params(
+            OCIVendors.GENERIC, {"tool_choice": "none"}
+        )
+        assert result["toolChoice"] == {"type": "NONE"}
+
+    def test_tool_choice_string_required_converted_to_dict(self):
+        config = self._config()
+        result = config._get_optional_params(
+            OCIVendors.GENERIC, {"tool_choice": "required"}
+        )
+        assert result["toolChoice"] == {"type": "REQUIRED"}
+
+    def test_response_format_json_generic(self):
+        config = self._config()
+        result = config._get_optional_params(
+            OCIVendors.GENERIC, {"response_format": {"type": "json_object"}}
+        )
+        assert result["responseFormat"]["type"] == "JSON_OBJECT"
+
+    def test_tools_adapted_for_cohere(self):
+        config = self._config()
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "echo",
+                    "description": "echo",
+                    "parameters": {
+                        "type": "object",
+                        "properties": {"msg": {"type": "string"}},
+                        "required": ["msg"],
+                    },
+                },
+            }
+        ]
+        result = config._get_optional_params(OCIVendors.COHERE, {"tools": tools})
+        # tools should be CohereTool objects
+        assert len(result["tools"]) == 1
+        assert result["tools"][0].name == "echo"
+
+    def test_tools_adapted_for_generic(self):
+        config = self._config()
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "search",
+                    "description": "search the web",
+                    "parameters": {
+                        "type": "object",
+                        "properties": {"query": {"type": "string"}},
+                    },
+                },
+            }
+        ]
+        result = config._get_optional_params(OCIVendors.GENERIC, {"tools": tools})
+        assert len(result["tools"]) == 1
+        assert result["tools"][0].name == "search"
+
+
+class TestOCIChatConfigTransformRequest:
+    _base_params = {**_MANUAL_CREDS}
+
+    def test_generic_model_transform(self):
+        config = OCIChatConfig()
+        result = config.transform_request(
+            model=_GENERIC_MODEL,
+            messages=[{"role": "user", "content": "hello"}],
+            optional_params=self._base_params,
+            litellm_params={},
+            headers={},
+        )
+        assert result["compartmentId"] == _MANUAL_CREDS["oci_compartment_id"]
+        chat_req = result["chatRequest"]
+        assert chat_req["apiFormat"] == "GENERIC"
+
+    def test_cohere_model_transform(self):
+        config = OCIChatConfig()
+        result = config.transform_request(
+            model=_COHERE_MODEL,
+            messages=[{"role": "user", "content": "tell me a joke"}],
+            optional_params=self._base_params,
+            litellm_params={},
+            headers={},
+        )
+        chat_req = result["chatRequest"]
+        assert chat_req["apiFormat"] == "COHERE"
+        assert chat_req["message"] == "tell me a joke"
+
+    def test_cohere_model_with_system_preamble(self):
+        config = OCIChatConfig()
+        result = config.transform_request(
+            model=_COHERE_MODEL,
+            messages=[
+                {"role": "system", "content": "You are helpful."},
+                {"role": "user", "content": "hi"},
+            ],
+            optional_params=self._base_params,
+            litellm_params={},
+            headers={},
+        )
+        assert result["chatRequest"]["preambleOverride"] == "You are helpful."
+
+    def test_raises_without_compartment_id(self):
+        config = OCIChatConfig()
+        params = {k: v for k, v in _MANUAL_CREDS.items() if k != "oci_compartment_id"}
+        with pytest.raises(OCIError) as exc_info:
+            config.transform_request(
+                model=_GENERIC_MODEL,
+                messages=[{"role": "user", "content": "hi"}],
+                optional_params=params,
+                litellm_params={},
+                headers={},
+            )
+        assert exc_info.value.status_code == 400
+        assert "oci_compartment_id" in str(exc_info.value)
+
+
+# ===========================================================================
+# transformation.py — OCIStreamWrapper.chunk_creator
+# ===========================================================================
+
+
+class TestOCIStreamWrapperChunkCreator:
+    def _make_wrapper(self, model: str) -> "OCIStreamWrapper":
+        from litellm.llms.oci.chat.transformation import OCIStreamWrapper
+
+        return OCIStreamWrapper(
+            completion_stream=iter([]),
+            model=model,
+            custom_llm_provider="oci",
+            logging_obj=MagicMock(),
+        )
+
+    def test_cohere_chunk_dispatched_correctly(self):
+        wrapper = self._make_wrapper(_COHERE_MODEL)
+        payload = json.dumps({"apiFormat": "COHERE", "text": "hi", "finishReason": None})
+        result = wrapper.chunk_creator(f"data:{payload}")
+        assert result.choices[0].delta.content == "hi"
+
+    def test_generic_chunk_dispatched_correctly(self):
+        wrapper = self._make_wrapper(_GENERIC_MODEL)
+        payload = json.dumps({
+            "finishReason": "COMPLETE",
+            "index": 0,
+        })
+        result = wrapper.chunk_creator(f"data:{payload}")
+        assert result.choices[0].finish_reason == "stop"
+
+    def test_raises_on_non_data_prefix(self):
+        wrapper = self._make_wrapper(_GENERIC_MODEL)
+        with pytest.raises(ValueError, match="does not start with 'data:'"):
+            wrapper.chunk_creator("event: done")
+
+    def test_raises_on_non_string_chunk(self):
+        wrapper = self._make_wrapper(_GENERIC_MODEL)
+        with pytest.raises(ValueError, match="not a string"):
+            wrapper.chunk_creator({"bad": "type"})
+
+
+# ===========================================================================
+# transformation.py — get_sync_custom_stream_wrapper
+# ===========================================================================
+
+
+def test_get_sync_custom_stream_wrapper_returns_wrapper():
+    from litellm.llms.oci.chat.transformation import OCIStreamWrapper
+
+    config = OCIChatConfig()
+
+    mock_response = MagicMock()
+    mock_response.status_code = 200
+    mock_response.iter_text.return_value = iter(
+        ['data:{"finishReason":"COMPLETE","index":0}']
+    )
+
+    mock_client = MagicMock()
+    mock_client.post.return_value = mock_response
+
+    wrapper = config.get_sync_custom_stream_wrapper(
+        model=_GENERIC_MODEL,
+        custom_llm_provider="oci",
+        logging_obj=MagicMock(),
+        api_base=_API_BASE,
+        headers={"authorization": "Signature ..."},
+        data={"chatRequest": {}},
+        messages=[{"role": "user", "content": "hi"}],
+        client=mock_client,
+        signed_json_body=b'{"chatRequest":{}}',
+    )
+
+    assert isinstance(wrapper, OCIStreamWrapper)
+    mock_client.post.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_get_async_custom_stream_wrapper_returns_wrapper():
+    from litellm.llms.oci.chat.transformation import OCIStreamWrapper
+
+    config = OCIChatConfig()
+
+    async def _fake_aiter_text():
+        yield 'data:{"finishReason":"COMPLETE","index":0}'
+
+    mock_response = MagicMock()
+    mock_response.status_code = 200
+    mock_response.aiter_text = _fake_aiter_text
+
+    mock_client = AsyncMock()
+    mock_client.post = AsyncMock(return_value=mock_response)
+
+    wrapper = await config.get_async_custom_stream_wrapper(
+        model=_GENERIC_MODEL,
+        custom_llm_provider="oci",
+        logging_obj=MagicMock(),
+        api_base=_API_BASE,
+        headers={"authorization": "Signature ..."},
+        data={"chatRequest": {}},
+        messages=[{"role": "user", "content": "hi"}],
+        client=mock_client,
+        signed_json_body=b'{"chatRequest":{}}',
+    )
+
+    assert isinstance(wrapper, OCIStreamWrapper)