Add Chat Completions wrapper with reasoning conversion

Implements Phase 5: OpenAI Chat Completions compatibility layer

Features:
- Wraps Responses API for single source of truth
- Automatically enables reasoning generation
- Converts reasoning items to <think> tags for Open WebUI
- Maintains OpenAI-compatible chat completion format
- Supports both streaming and non-streaming modes
- Pipeline prefix preservation for model names
- System message handling

Architecture:
- Service layer calls Responses API internally
- Streams word-by-word for smooth UX
- Reasoning displayed in thought bubbles (Open WebUI)
- Main response shown separately from thinking

Error Handling:
- Enhanced exception types (RateLimitError, ContextLengthError)
- OpenAI-compatible error format
- Graceful error propagation from Responses API

Testing:
- 6 unit tests for chat router functionality
- 6 unit tests for streaming wrapper behavior
- Total: 12 tests with comprehensive coverage

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
This commit is contained in:
2025-12-06 19:38:35 +01:00
co-authored by Claude
parent ff6c3cf1b5
commit 5e40704d91
4 changed files with 509 additions and 46 deletions
+160 -44
View File
@@ -1,12 +1,15 @@
"""
Chat completion service.
Currently returns mock responses with lorem ipsum.
TODO: Integrate with Ollama/PydanticAI in future.
Wrapper around Responses API that converts to Chat Completions format.
Embeds reasoning in <think> tags for Open WebUI compatibility.
"""
import asyncio
import time
import uuid
from typing import AsyncGenerator
from src.agents.registry import ModelRegistry
from src.chat import constants
from src.chat.schemas import (
ChatCompletionChunk,
@@ -20,29 +23,67 @@ from src.chat.schemas import (
)
# Mock lorem ipsum response
MOCK_RESPONSE = (
"Lorem ipsum dolor sit amet, consectetur adipiscing elit. "
"Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. "
"Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris."
)
async def create_chat_completion(
request: ChatCompletionRequest,
) -> ChatCompletionResponse:
"""
Create chat completion (mock implementation).
Create chat completion by wrapping Responses API.
Converts Responses API output to Chat Completions format with
reasoning embedded in <think> tags for Open WebUI.
Args:
request: Chat completion request
Returns:
Mock chat completion response with lorem ipsum
Chat completion response with reasoning as <think> tags
"""
completion_id = f"chatcmpl-{uuid.uuid4().hex[:24]}"
created_at = int(time.time())
# Strip pipeline prefix if present
model_id = request.model
if "." in model_id:
model_id = model_id.split(".", 1)[1]
# Get agent and generate response
agent = ModelRegistry.get_agent(model_id)
# Convert Chat messages to Responses format
input_messages = [
{"role": msg.role, "content": msg.content}
for msg in request.messages
]
# Collect output items from agent (with reasoning enabled)
output_items = []
async for item in agent.generate_response(
messages=input_messages,
reasoning={"effort": "medium", "summary": "auto"}, # Enable reasoning
temperature=request.temperature or 1.0,
max_tokens=request.max_tokens,
stop=request.stop if isinstance(request.stop, list) else ([request.stop] if request.stop else None),
):
output_items.append(item)
# Build content with <think> tags
content_parts = []
# Add reasoning as <think> blocks
for item in output_items:
if item.type == "reasoning":
reasoning_text = "\n".join(item.data.get("summary", []))
content_parts.append(f"<think>\n{reasoning_text}\n</think>\n\n")
elif item.type == "message":
content_parts.append(item.data["content"][0]["text"])
content = "".join(content_parts)
# Calculate token usage (approximate)
prompt_text = " ".join(m.content for m in request.messages)
prompt_tokens = len(prompt_text) // 4
completion_tokens = len(content) // 4
return ChatCompletionResponse(
id=completion_id,
object=constants.CHAT_COMPLETION_OBJECT,
@@ -53,16 +94,15 @@ async def create_chat_completion(
index=0,
message=ChatMessage(
role=constants.ROLE_ASSISTANT,
content=MOCK_RESPONSE,
content=content,
),
finish_reason=constants.FINISH_REASON_STOP,
)
],
usage=ChatCompletionUsage(
prompt_tokens=len(" ".join(m.content for m in request.messages).split()),
completion_tokens=len(MOCK_RESPONSE.split()),
total_tokens=len(" ".join(m.content for m in request.messages).split())
+ len(MOCK_RESPONSE.split()),
prompt_tokens=prompt_tokens,
completion_tokens=completion_tokens,
total_tokens=prompt_tokens + completion_tokens,
),
)
@@ -71,20 +111,33 @@ async def create_chat_completion_stream(
request: ChatCompletionRequest,
) -> AsyncGenerator[ChatCompletionChunk, None]:
"""
Create streaming chat completion (mock implementation).
Create streaming chat completion by wrapping Responses API.
Streams reasoning in <think> tags followed by message content.
Args:
request: Chat completion request with stream=True
Yields:
Mock chat completion chunks with lorem ipsum
Chat completion chunks with reasoning as <think> tags
"""
completion_id = f"chatcmpl-{uuid.uuid4().hex[:24]}"
created_at = int(time.time())
# Split response into words for streaming simulation
words = MOCK_RESPONSE.split()
# Strip pipeline prefix if present
model_id = request.model
if "." in model_id:
model_id = model_id.split(".", 1)[1]
# Get agent
agent = ModelRegistry.get_agent(model_id)
# Convert Chat messages to Responses format
input_messages = [
{"role": msg.role, "content": msg.content}
for msg in request.messages
]
# First chunk with role
yield ChatCompletionChunk(
id=completion_id,
@@ -99,23 +152,86 @@ async def create_chat_completion_stream(
)
],
)
# Stream words
for word in words:
yield ChatCompletionChunk(
id=completion_id,
object=constants.CHAT_COMPLETION_CHUNK_OBJECT,
created=created_at,
model=request.model,
choices=[
ChatCompletionChunkChoice(
index=0,
delta=ChatCompletionChunkDelta(content=f"{word} "),
finish_reason=None,
# Stream from agent with reasoning enabled
in_reasoning = False
async for item in agent.generate_response(
messages=input_messages,
reasoning={"effort": "medium", "summary": "auto"}, # Enable reasoning
temperature=request.temperature or 1.0,
max_tokens=request.max_tokens,
stop=request.stop if isinstance(request.stop, list) else ([request.stop] if request.stop else None),
):
if item.type == "reasoning":
# Start <think> block
if not in_reasoning:
yield ChatCompletionChunk(
id=completion_id,
object=constants.CHAT_COMPLETION_CHUNK_OBJECT,
created=created_at,
model=request.model,
choices=[
ChatCompletionChunkChoice(
index=0,
delta=ChatCompletionChunkDelta(content="<think>\n"),
finish_reason=None,
)
],
)
],
)
in_reasoning = True
# Stream reasoning summary steps
for step in item.data.get("summary", []):
yield ChatCompletionChunk(
id=completion_id,
object=constants.CHAT_COMPLETION_CHUNK_OBJECT,
created=created_at,
model=request.model,
choices=[
ChatCompletionChunkChoice(
index=0,
delta=ChatCompletionChunkDelta(content=f"{step}\n"),
finish_reason=None,
)
],
)
await asyncio.sleep(0.05) # Simulate typing
# Close <think> block
yield ChatCompletionChunk(
id=completion_id,
object=constants.CHAT_COMPLETION_CHUNK_OBJECT,
created=created_at,
model=request.model,
choices=[
ChatCompletionChunkChoice(
index=0,
delta=ChatCompletionChunkDelta(content="</think>\n\n"),
finish_reason=None,
)
],
)
in_reasoning = False
elif item.type == "message":
# Stream message content word by word
text = item.data["content"][0]["text"]
for word in text.split():
yield ChatCompletionChunk(
id=completion_id,
object=constants.CHAT_COMPLETION_CHUNK_OBJECT,
created=created_at,
model=request.model,
choices=[
ChatCompletionChunkChoice(
index=0,
delta=ChatCompletionChunkDelta(content=f"{word} "),
finish_reason=None,
)
],
)
await asyncio.sleep(0.05) # Simulate typing
# Final chunk with finish_reason
yield ChatCompletionChunk(
id=completion_id,
+22 -1
View File
@@ -47,6 +47,27 @@ class ModelNotFoundError(AppException):
class ValidationError(AppException):
"""Raised for validation errors."""
def __init__(self, message: str, details: dict[str, Any] | None = None):
super().__init__(message=message, status_code=422, details=details)
class RateLimitError(AppException):
"""Raised when rate limit is exceeded."""
def __init__(self, message: str = "Rate limit exceeded"):
super().__init__(message=message, status_code=429)
class ContextLengthError(AppException):
"""Raised when context length exceeds model limits."""
def __init__(self, message: str = "Context length exceeded"):
super().__init__(message=message, status_code=400)
class APIError(AppException):
"""Generic API error."""
def __init__(self, message: str, status_code: int = 500):
super().__init__(message=message, status_code=status_code)
+1 -1
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@@ -46,7 +46,7 @@ def test_chat_completion_non_streaming(
def test_chat_completion_validation_error(client: TestClient) -> None:
"""Test chat completion with invalid request."""
# Missing required field 'messages'
invalid_request = {"model": "mistral-nemo:latest"}
invalid_request = {"model": "tatlock"}
response = client.post("/v1/chat/completions", json=invalid_request)
+326
View File
@@ -0,0 +1,326 @@
"""
Tests for chat completions streaming wrapper.
Tests that the wrapper correctly:
- Wraps Responses API
- Enables reasoning automatically
- Converts reasoning to <think> tags
- Streams both reasoning and content
"""
import json
import pytest
from httpx import AsyncClient
from src.chat import constants
@pytest.mark.unit
@pytest.mark.asyncio
async def test_streaming_wrapper_enables_reasoning(async_client: AsyncClient):
"""Test that streaming wrapper automatically enables reasoning."""
request_data = {
"model": "lorem-tester",
"messages": [
{"role": "user", "content": "Test message"}
],
"stream": True
}
chunks_received = []
think_tags_found = False
async with async_client.stream(
"POST",
"/v1/chat/completions",
json=request_data,
timeout=20.0,
) as response:
assert response.status_code == 200
assert response.headers["content-type"] == "text/event-stream; charset=utf-8"
async for line in response.aiter_lines():
if not line.strip():
continue
if line.startswith("data: "):
data_str = line[6:].strip()
if data_str == "[DONE]":
break
try:
chunk = json.loads(data_str)
chunks_received.append(chunk)
# Check for <think> tags in delta content
if "choices" in chunk and len(chunk["choices"]) > 0:
delta = chunk["choices"][0].get("delta", {})
content = delta.get("content")
if content and ("<think>" in content or "</think>" in content):
think_tags_found = True
except json.JSONDecodeError:
pass
# Should have received chunks
assert len(chunks_received) > 0
# Should have found <think> tags (reasoning enabled automatically)
assert think_tags_found, "Expected <think> tags in streaming output"
@pytest.mark.unit
@pytest.mark.asyncio
async def test_streaming_wrapper_reasoning_before_content(async_client: AsyncClient):
"""Test that reasoning (<think> tags) comes before actual content."""
request_data = {
"model": "lorem-tester",
"messages": [
{"role": "user", "content": "Explain something"}
],
"stream": True
}
all_content = []
found_think_opening = False
found_think_closing = False
found_content_after_think = False
async with async_client.stream(
"POST",
"/v1/chat/completions",
json=request_data,
timeout=20.0,
) as response:
assert response.status_code == 200
async for line in response.aiter_lines():
if not line.strip():
continue
if line.startswith("data: "):
data_str = line[6:].strip()
if data_str == "[DONE]":
break
try:
chunk = json.loads(data_str)
if "choices" in chunk and len(chunk["choices"]) > 0:
delta = chunk["choices"][0].get("delta", {})
content = delta.get("content", "")
if content:
all_content.append(content)
if "<think>" in content:
found_think_opening = True
if "</think>" in content:
found_think_closing = True
# Content after closing think tag
if found_think_closing and content.strip() and "<think>" not in content and "</think>" not in content:
found_content_after_think = True
except json.JSONDecodeError:
pass
# Verify ordering
full_text = "".join(all_content)
if found_think_opening and found_think_closing:
# Reasoning should come before main content
think_start = full_text.index("<think>")
think_end = full_text.index("</think>")
assert think_start < think_end, "Opening <think> should come before closing </think>"
@pytest.mark.unit
@pytest.mark.asyncio
async def test_streaming_wrapper_proper_chunk_structure(async_client: AsyncClient):
"""Test that streaming chunks have proper structure."""
request_data = {
"model": "lorem-tester",
"messages": [
{"role": "user", "content": "Hello"}
],
"temperature": 0.8,
"stream": True
}
first_chunk = None
last_chunk = None
chunk_count = 0
async with async_client.stream(
"POST",
"/v1/chat/completions",
json=request_data,
timeout=20.0,
) as response:
assert response.status_code == 200
async for line in response.aiter_lines():
if not line.strip():
continue
if line.startswith("data: "):
data_str = line[6:].strip()
if data_str == "[DONE]":
break
try:
chunk = json.loads(data_str)
chunk_count += 1
# Verify chunk structure
assert "id" in chunk
assert "object" in chunk
assert chunk["object"] == constants.CHAT_COMPLETION_CHUNK_OBJECT
assert "created" in chunk
assert "model" in chunk
assert chunk["model"] == "lorem-tester"
assert "choices" in chunk
assert len(chunk["choices"]) == 1
choice = chunk["choices"][0]
assert "index" in choice
assert choice["index"] == 0
assert "delta" in choice
if first_chunk is None:
first_chunk = chunk
last_chunk = chunk
except json.JSONDecodeError:
pass
# Verify we got chunks
assert chunk_count > 0
assert first_chunk is not None
assert last_chunk is not None
# First chunk should have role
assert first_chunk["choices"][0]["delta"].get("role") == constants.ROLE_ASSISTANT
# Last chunk should have finish_reason
assert last_chunk["choices"][0].get("finish_reason") == constants.FINISH_REASON_STOP
@pytest.mark.unit
@pytest.mark.asyncio
async def test_streaming_wrapper_with_system_message(async_client: AsyncClient):
"""Test streaming with system message."""
request_data = {
"model": "lorem-tester",
"messages": [
{"role": "system", "content": "You are a helpful assistant."},
{"role": "user", "content": "Hello"}
],
"stream": True
}
chunks_received = []
async with async_client.stream(
"POST",
"/v1/chat/completions",
json=request_data,
timeout=20.0,
) as response:
assert response.status_code == 200
async for line in response.aiter_lines():
if not line.strip():
continue
if line.startswith("data: "):
data_str = line[6:].strip()
if data_str == "[DONE]":
break
try:
chunk = json.loads(data_str)
chunks_received.append(chunk)
except json.JSONDecodeError:
pass
# Should handle system message properly
assert len(chunks_received) > 0
# First chunk should still have assistant role
assert chunks_received[0]["choices"][0]["delta"].get("role") == constants.ROLE_ASSISTANT
@pytest.mark.unit
@pytest.mark.asyncio
async def test_streaming_wrapper_pipeline_prefix(async_client: AsyncClient):
"""Test streaming with pipeline prefix in model name."""
request_data = {
"model": "some_pipeline.lorem-tester",
"messages": [
{"role": "user", "content": "Test"}
],
"stream": True
}
chunks_received = []
async with async_client.stream(
"POST",
"/v1/chat/completions",
json=request_data,
timeout=20.0,
) as response:
assert response.status_code == 200
async for line in response.aiter_lines():
if not line.strip():
continue
if line.startswith("data: "):
data_str = line[6:].strip()
if data_str == "[DONE]":
break
try:
chunk = json.loads(data_str)
chunks_received.append(chunk)
# Model should keep original name (with prefix)
assert chunk["model"] == "some_pipeline.lorem-tester"
except json.JSONDecodeError:
pass
assert len(chunks_received) > 0
@pytest.mark.unit
@pytest.mark.asyncio
async def test_streaming_wrapper_non_streaming_fallback(async_client: AsyncClient):
"""Test that non-streaming request works through wrapper."""
request_data = {
"model": "lorem-tester",
"messages": [
{"role": "user", "content": "Hello"}
],
"stream": False # Non-streaming
}
response = await async_client.post(
"/v1/chat/completions",
json=request_data,
timeout=20.0
)
assert response.status_code == 200
data = response.json()
# Verify structure
assert "id" in data
assert "object" in data
assert data["object"] == constants.CHAT_COMPLETION_OBJECT
assert "choices" in data
assert len(data["choices"]) == 1
choice = data["choices"][0]
assert "message" in choice
assert choice["message"]["role"] == constants.ROLE_ASSISTANT
assert choice["message"]["content"] # Should have content
# Should have <think> tags in content (reasoning enabled)
assert "<think>" in choice["message"]["content"]
assert "</think>" in choice["message"]["content"]