refactor: remove dead inference API code and clean up imports (#4093)

# What does this PR do?

Delete ~2,000 lines of dead code from the old bespoke inference API that
was replaced by OpenAI-only API. This includes removing unused type
conversion functions, dead provider methods, and event_logger.py.

Clean up imports across the codebase to remove references to deleted
types. This eliminates unnecessary
code and dependencies, helping isolate the API package as a
self-contained module.

This is the last interdependency between the .api package and "exterior"
packages, meaning that now every other package in llama stack imports
the API, not the other way around.

## Test Plan

this is a structural change, no tests needed.

---------

Signed-off-by: Charlie Doern <cdoern@redhat.com>

tests/unit/providers/inline/inference/__init__.py

@@ -0,0 +1,5 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.

tests/unit/providers/inline/inference/test_meta_reference.py

@@ -0,0 +1,44 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from unittest.mock import Mock
+
+import pytest
+
+from llama_stack.providers.inline.inference.meta_reference.model_parallel import (
+    ModelRunner,
+)
+
+
+class TestModelRunner:
+    """Test ModelRunner task dispatching for model-parallel inference."""
+
+    def test_chat_completion_task_dispatch(self):
+        """Verify ModelRunner correctly dispatches chat_completion tasks."""
+        # Create a mock generator
+        mock_generator = Mock()
+        mock_generator.chat_completion = Mock(return_value=iter([]))
+
+        runner = ModelRunner(mock_generator)
+
+        # Create a chat_completion task
+        fake_params = {"model": "test"}
+        fake_messages = [{"role": "user", "content": "test"}]
+        task = ("chat_completion", [fake_params, fake_messages])
+
+        # Execute task
+        runner(task)
+
+        # Verify chat_completion was called with correct arguments
+        mock_generator.chat_completion.assert_called_once_with(fake_params, fake_messages)
+
+    def test_invalid_task_type_raises_error(self):
+        """Verify ModelRunner rejects invalid task types."""
+        mock_generator = Mock()
+        runner = ModelRunner(mock_generator)
+
+        with pytest.raises(ValueError, match="Unexpected task type"):
+            runner(("invalid_task", []))

tests/unit/providers/nvidia/test_safety.py

@@ -10,11 +10,13 @@ from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
-from llama_stack.apis.inference import CompletionMessage, UserMessage
+from llama_stack.apis.inference import (
+    OpenAIAssistantMessageParam,
+    OpenAIUserMessageParam,
+)
 from llama_stack.apis.resource import ResourceType
 from llama_stack.apis.safety import RunShieldResponse, ViolationLevel
 from llama_stack.apis.shields import Shield
-from llama_stack.models.llama.datatypes import StopReason
 from llama_stack.providers.remote.safety.nvidia.config import NVIDIASafetyConfig
 from llama_stack.providers.remote.safety.nvidia.nvidia import NVIDIASafetyAdapter
 
@@ -136,11 +138,9 @@ async def test_run_shield_allowed(nvidia_adapter, mock_guardrails_post):
 
     # Run the shield
     messages = [
-        UserMessage(role="user", content="Hello, how are you?"),
-        CompletionMessage(
-            role="assistant",
+        OpenAIUserMessageParam(content="Hello, how are you?"),
+        OpenAIAssistantMessageParam(
             content="I'm doing well, thank you for asking!",
-            stop_reason=StopReason.end_of_message,
             tool_calls=[],
         ),
     ]
@@ -191,13 +191,10 @@ async def test_run_shield_blocked(nvidia_adapter, mock_guardrails_post):
     # Mock Guardrails API response
     mock_guardrails_post.return_value = {"status": "blocked", "rails_status": {"reason": "harmful_content"}}
 
-    # Run the shield
     messages = [
-        UserMessage(role="user", content="Hello, how are you?"),
-        CompletionMessage(
-            role="assistant",
+        OpenAIUserMessageParam(content="Hello, how are you?"),
+        OpenAIAssistantMessageParam(
             content="I'm doing well, thank you for asking!",
-            stop_reason=StopReason.end_of_message,
             tool_calls=[],
         ),
     ]
@@ -243,7 +240,7 @@ async def test_run_shield_not_found(nvidia_adapter, mock_guardrails_post):
     adapter.shield_store.get_shield.return_value = None
 
     messages = [
-        UserMessage(role="user", content="Hello, how are you?"),
+        OpenAIUserMessageParam(content="Hello, how are you?"),
     ]
 
     with pytest.raises(ValueError):
@@ -274,11 +271,9 @@ async def test_run_shield_http_error(nvidia_adapter, mock_guardrails_post):
 
     # Running the shield should raise an exception
     messages = [
-        UserMessage(role="user", content="Hello, how are you?"),
-        CompletionMessage(
-            role="assistant",
+        OpenAIUserMessageParam(content="Hello, how are you?"),
+        OpenAIAssistantMessageParam(
             content="I'm doing well, thank you for asking!",
-            stop_reason=StopReason.end_of_message,
             tool_calls=[],
         ),
     ]

tests/unit/providers/utils/inference/test_openai_compat.py

@@ -1,220 +0,0 @@
-# Copyright (c) Meta Platforms, Inc. and affiliates.
-# All rights reserved.
-#
-# This source code is licensed under the terms described in the LICENSE file in
-# the root directory of this source tree.
-
-import pytest
-from pydantic import ValidationError
-
-from llama_stack.apis.common.content_types import TextContentItem
-from llama_stack.apis.inference import (
-    CompletionMessage,
-    OpenAIAssistantMessageParam,
-    OpenAIChatCompletionContentPartImageParam,
-    OpenAIChatCompletionContentPartTextParam,
-    OpenAIDeveloperMessageParam,
-    OpenAIImageURL,
-    OpenAISystemMessageParam,
-    OpenAIToolMessageParam,
-    OpenAIUserMessageParam,
-    SystemMessage,
-    UserMessage,
-)
-from llama_stack.models.llama.datatypes import BuiltinTool, StopReason, ToolCall
-from llama_stack.providers.utils.inference.openai_compat import (
-    convert_message_to_openai_dict,
-    convert_message_to_openai_dict_new,
-    openai_messages_to_messages,
-)
-
-
-async def test_convert_message_to_openai_dict():
-    message = UserMessage(content=[TextContentItem(text="Hello, world!")], role="user")
-    assert await convert_message_to_openai_dict(message) == {
-        "role": "user",
-        "content": [{"type": "text", "text": "Hello, world!"}],
-    }
-
-
-# Test convert_message_to_openai_dict with a tool call
-async def test_convert_message_to_openai_dict_with_tool_call():
-    message = CompletionMessage(
-        content="",
-        tool_calls=[ToolCall(call_id="123", tool_name="test_tool", arguments='{"foo": "bar"}')],
-        stop_reason=StopReason.end_of_turn,
-    )
-
-    openai_dict = await convert_message_to_openai_dict(message)
-
-    assert openai_dict == {
-        "role": "assistant",
-        "content": [{"type": "text", "text": ""}],
-        "tool_calls": [
-            {"id": "123", "type": "function", "function": {"name": "test_tool", "arguments": '{"foo": "bar"}'}}
-        ],
-    }
-
-
-async def test_convert_message_to_openai_dict_with_builtin_tool_call():
-    message = CompletionMessage(
-        content="",
-        tool_calls=[
-            ToolCall(
-                call_id="123",
-                tool_name=BuiltinTool.brave_search,
-                arguments='{"foo": "bar"}',
-            )
-        ],
-        stop_reason=StopReason.end_of_turn,
-    )
-
-    openai_dict = await convert_message_to_openai_dict(message)
-
-    assert openai_dict == {
-        "role": "assistant",
-        "content": [{"type": "text", "text": ""}],
-        "tool_calls": [
-            {"id": "123", "type": "function", "function": {"name": "brave_search", "arguments": '{"foo": "bar"}'}}
-        ],
-    }
-
-
-async def test_openai_messages_to_messages_with_content_str():
-    openai_messages = [
-        OpenAISystemMessageParam(content="system message"),
-        OpenAIUserMessageParam(content="user message"),
-        OpenAIAssistantMessageParam(content="assistant message"),
-    ]
-
-    llama_messages = openai_messages_to_messages(openai_messages)
-    assert len(llama_messages) == 3
-    assert isinstance(llama_messages[0], SystemMessage)
-    assert isinstance(llama_messages[1], UserMessage)
-    assert isinstance(llama_messages[2], CompletionMessage)
-    assert llama_messages[0].content == "system message"
-    assert llama_messages[1].content == "user message"
-    assert llama_messages[2].content == "assistant message"
-
-
-async def test_openai_messages_to_messages_with_content_list():
-    openai_messages = [
-        OpenAISystemMessageParam(content=[OpenAIChatCompletionContentPartTextParam(text="system message")]),
-        OpenAIUserMessageParam(content=[OpenAIChatCompletionContentPartTextParam(text="user message")]),
-        OpenAIAssistantMessageParam(content=[OpenAIChatCompletionContentPartTextParam(text="assistant message")]),
-    ]
-
-    llama_messages = openai_messages_to_messages(openai_messages)
-    assert len(llama_messages) == 3
-    assert isinstance(llama_messages[0], SystemMessage)
-    assert isinstance(llama_messages[1], UserMessage)
-    assert isinstance(llama_messages[2], CompletionMessage)
-    assert llama_messages[0].content[0].text == "system message"
-    assert llama_messages[1].content[0].text == "user message"
-    assert llama_messages[2].content[0].text == "assistant message"
-
-
-@pytest.mark.parametrize(
-    "message_class,kwargs",
-    [
-        (OpenAISystemMessageParam, {}),
-        (OpenAIAssistantMessageParam, {}),
-        (OpenAIDeveloperMessageParam, {}),
-        (OpenAIUserMessageParam, {}),
-        (OpenAIToolMessageParam, {"tool_call_id": "call_123"}),
-    ],
-)
-def test_message_accepts_text_string(message_class, kwargs):
-    """Test that messages accept string text content."""
-    msg = message_class(content="Test message", **kwargs)
-    assert msg.content == "Test message"
-
-
-@pytest.mark.parametrize(
-    "message_class,kwargs",
-    [
-        (OpenAISystemMessageParam, {}),
-        (OpenAIAssistantMessageParam, {}),
-        (OpenAIDeveloperMessageParam, {}),
-        (OpenAIUserMessageParam, {}),
-        (OpenAIToolMessageParam, {"tool_call_id": "call_123"}),
-    ],
-)
-def test_message_accepts_text_list(message_class, kwargs):
-    """Test that messages accept list of text content parts."""
-    content_list = [OpenAIChatCompletionContentPartTextParam(text="Test message")]
-    msg = message_class(content=content_list, **kwargs)
-    assert len(msg.content) == 1
-    assert msg.content[0].text == "Test message"
-
-
-@pytest.mark.parametrize(
-    "message_class,kwargs",
-    [
-        (OpenAISystemMessageParam, {}),
-        (OpenAIAssistantMessageParam, {}),
-        (OpenAIDeveloperMessageParam, {}),
-        (OpenAIToolMessageParam, {"tool_call_id": "call_123"}),
-    ],
-)
-def test_message_rejects_images(message_class, kwargs):
-    """Test that system, assistant, developer, and tool messages reject image content."""
-    with pytest.raises(ValidationError):
-        message_class(
-            content=[
-                OpenAIChatCompletionContentPartImageParam(image_url=OpenAIImageURL(url="http://example.com/image.jpg"))
-            ],
-            **kwargs,
-        )
-
-
-def test_user_message_accepts_images():
-    """Test that user messages accept image content (unlike other message types)."""
-    # List with images should work
-    msg = OpenAIUserMessageParam(
-        content=[
-            OpenAIChatCompletionContentPartTextParam(text="Describe this image:"),
-            OpenAIChatCompletionContentPartImageParam(image_url=OpenAIImageURL(url="http://example.com/image.jpg")),
-        ]
-    )
-    assert len(msg.content) == 2
-    assert msg.content[0].text == "Describe this image:"
-    assert msg.content[1].image_url.url == "http://example.com/image.jpg"
-
-
-async def test_convert_message_to_openai_dict_new_user_message():
-    """Test convert_message_to_openai_dict_new with UserMessage."""
-    message = UserMessage(content="Hello, world!", role="user")
-    result = await convert_message_to_openai_dict_new(message)
-
-    assert result["role"] == "user"
-    assert result["content"] == "Hello, world!"
-
-
-async def test_convert_message_to_openai_dict_new_completion_message_with_tool_calls():
-    """Test convert_message_to_openai_dict_new with CompletionMessage containing tool calls."""
-    message = CompletionMessage(
-        content="I'll help you find the weather.",
-        tool_calls=[
-            ToolCall(
-                call_id="call_123",
-                tool_name="get_weather",
-                arguments='{"city": "Sligo"}',
-            )
-        ],
-        stop_reason=StopReason.end_of_turn,
-    )
-    result = await convert_message_to_openai_dict_new(message)
-
-    # This would have failed with "Cannot instantiate typing.Union" before the fix
-    assert result["role"] == "assistant"
-    assert result["content"] == "I'll help you find the weather."
-    assert "tool_calls" in result
-    assert result["tool_calls"] is not None
-    assert len(result["tool_calls"]) == 1
-
-    tool_call = result["tool_calls"][0]
-    assert tool_call.id == "call_123"
-    assert tool_call.type == "function"
-    assert tool_call.function.name == "get_weather"
-    assert tool_call.function.arguments == '{"city": "Sligo"}'

tests/unit/providers/utils/inference/test_prompt_adapter.py

@@ -0,0 +1,35 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+from llama_stack.apis.inference import (
+    OpenAIAssistantMessageParam,
+    OpenAIUserMessageParam,
+)
+from llama_stack.models.llama.datatypes import RawTextItem
+from llama_stack.providers.utils.inference.prompt_adapter import (
+    convert_openai_message_to_raw_message,
+)
+
+
+class TestConvertOpenAIMessageToRawMessage:
+    """Test conversion of OpenAI message types to RawMessage format."""
+
+    async def test_user_message_conversion(self):
+        msg = OpenAIUserMessageParam(role="user", content="Hello world")
+        raw_msg = await convert_openai_message_to_raw_message(msg)
+
+        assert raw_msg.role == "user"
+        assert isinstance(raw_msg.content, RawTextItem)
+        assert raw_msg.content.text == "Hello world"
+
+    async def test_assistant_message_conversion(self):
+        msg = OpenAIAssistantMessageParam(role="assistant", content="Hi there!")
+        raw_msg = await convert_openai_message_to_raw_message(msg)
+
+        assert raw_msg.role == "assistant"
+        assert isinstance(raw_msg.content, RawTextItem)
+        assert raw_msg.content.text == "Hi there!"
+        assert raw_msg.tool_calls == []