feat(#124): add OpenAI LLM provider

Implement OpenAI provider for GPT-4, GPT-3.5, and other OpenAI models.

Implementation includes:
- OpenAI SDK integration with API key authentication
- Chat completion with streaming support
- Embeddings generation
- Health checks and model listing
- OpenTelemetry tracing
- Comprehensive test suite with 97% coverage

Follows TDD methodology:
- Written tests first (RED phase)
- Implemented minimal code to pass tests (GREEN phase)
- Code passes typecheck, linter, and all quality gates

Test coverage: 97.18% statements, 97.05% lines
All 22 tests passing

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
2026-01-31 14:21:38 -06:00
parent faf6328e0b
commit 0fdcfa6ed3
3 changed files with 875 additions and 0 deletions

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export * from "./llm-provider.interface";
export * from "./openai.provider";
export * from "./ollama.provider";

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import { describe, it, expect, beforeEach, vi, type Mock } from "vitest";
import { OpenAiProvider, type OpenAiProviderConfig } from "./openai.provider";
import type { ChatRequestDto, EmbedRequestDto } from "../dto";
// Mock the openai module
vi.mock("openai", () => {
return {
default: vi.fn().mockImplementation(function (this: unknown) {
return {
chat: {
completions: {
create: vi.fn(),
},
},
embeddings: {
create: vi.fn(),
},
models: {
list: vi.fn(),
},
};
}),
};
});
describe("OpenAiProvider", () => {
let provider: OpenAiProvider;
let config: OpenAiProviderConfig;
let mockOpenAiInstance: {
chat: { completions: { create: Mock } };
embeddings: { create: Mock };
models: { list: Mock };
};
beforeEach(() => {
// Reset all mocks
vi.clearAllMocks();
// Setup test configuration
config = {
endpoint: "https://api.openai.com/v1",
apiKey: "sk-test-1234567890",
timeout: 30000,
};
provider = new OpenAiProvider(config);
// Get the mock instance created by the constructor
mockOpenAiInstance = (provider as any).client;
});
describe("constructor and initialization", () => {
it("should create provider with correct name and type", () => {
expect(provider.name).toBe("OpenAI");
expect(provider.type).toBe("openai");
});
it("should initialize successfully", async () => {
await expect(provider.initialize()).resolves.toBeUndefined();
});
it("should support organization ID in config", () => {
const configWithOrg: OpenAiProviderConfig = {
endpoint: "https://api.openai.com/v1",
apiKey: "sk-test-1234567890",
organization: "org-test123",
};
const providerWithOrg = new OpenAiProvider(configWithOrg);
const returnedConfig = providerWithOrg.getConfig();
expect(returnedConfig.organization).toBe("org-test123");
});
});
describe("checkHealth", () => {
it("should return healthy status when OpenAI is reachable", async () => {
const mockModels = {
data: [{ id: "gpt-4" }, { id: "gpt-3.5-turbo" }, { id: "text-embedding-ada-002" }],
};
mockOpenAiInstance.models.list.mockResolvedValue(mockModels);
const health = await provider.checkHealth();
expect(health).toEqual({
healthy: true,
provider: "openai",
endpoint: config.endpoint,
models: ["gpt-4", "gpt-3.5-turbo", "text-embedding-ada-002"],
});
expect(mockOpenAiInstance.models.list).toHaveBeenCalledOnce();
});
it("should return unhealthy status when OpenAI is unreachable", async () => {
const error = new Error("API key invalid");
mockOpenAiInstance.models.list.mockRejectedValue(error);
const health = await provider.checkHealth();
expect(health).toEqual({
healthy: false,
provider: "openai",
endpoint: config.endpoint,
error: "API key invalid",
});
});
it("should handle non-Error exceptions", async () => {
mockOpenAiInstance.models.list.mockRejectedValue("string error");
const health = await provider.checkHealth();
expect(health.healthy).toBe(false);
expect(health.error).toBe("string error");
});
});
describe("listModels", () => {
it("should return array of model names", async () => {
const mockModels = {
data: [{ id: "gpt-4" }, { id: "gpt-3.5-turbo" }, { id: "gpt-4-turbo" }],
};
mockOpenAiInstance.models.list.mockResolvedValue(mockModels);
const models = await provider.listModels();
expect(models).toEqual(["gpt-4", "gpt-3.5-turbo", "gpt-4-turbo"]);
expect(mockOpenAiInstance.models.list).toHaveBeenCalledOnce();
});
it("should throw error when listing models fails", async () => {
const error = new Error("Failed to connect");
mockOpenAiInstance.models.list.mockRejectedValue(error);
await expect(provider.listModels()).rejects.toThrow("Failed to list models");
});
});
describe("chat", () => {
it("should perform chat completion successfully", async () => {
const request: ChatRequestDto = {
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
};
const mockResponse = {
id: "chatcmpl-123",
object: "chat.completion",
created: 1677652288,
model: "gpt-4",
choices: [
{
index: 0,
message: {
role: "assistant",
content: "Hello! How can I assist you today?",
},
finish_reason: "stop",
},
],
usage: {
prompt_tokens: 10,
completion_tokens: 8,
total_tokens: 18,
},
};
mockOpenAiInstance.chat.completions.create.mockResolvedValue(mockResponse);
const response = await provider.chat(request);
expect(response).toEqual({
model: "gpt-4",
message: { role: "assistant", content: "Hello! How can I assist you today?" },
done: true,
promptEvalCount: 10,
evalCount: 8,
});
expect(mockOpenAiInstance.chat.completions.create).toHaveBeenCalledWith({
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
stream: false,
});
});
it("should include system prompt in messages", async () => {
const request: ChatRequestDto = {
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
systemPrompt: "You are a helpful assistant",
};
mockOpenAiInstance.chat.completions.create.mockResolvedValue({
model: "gpt-4",
choices: [
{
message: { role: "assistant", content: "Hi!" },
finish_reason: "stop",
},
],
usage: { prompt_tokens: 15, completion_tokens: 2, total_tokens: 17 },
});
await provider.chat(request);
expect(mockOpenAiInstance.chat.completions.create).toHaveBeenCalledWith({
model: "gpt-4",
messages: [
{ role: "system", content: "You are a helpful assistant" },
{ role: "user", content: "Hello" },
],
stream: false,
});
});
it("should not duplicate system prompt when already in messages", async () => {
const request: ChatRequestDto = {
model: "gpt-4",
messages: [
{ role: "system", content: "Existing system prompt" },
{ role: "user", content: "Hello" },
],
systemPrompt: "New system prompt (should be ignored)",
};
mockOpenAiInstance.chat.completions.create.mockResolvedValue({
model: "gpt-4",
choices: [
{
message: { role: "assistant", content: "Hi!" },
finish_reason: "stop",
},
],
usage: { prompt_tokens: 15, completion_tokens: 2, total_tokens: 17 },
});
await provider.chat(request);
expect(mockOpenAiInstance.chat.completions.create).toHaveBeenCalledWith({
model: "gpt-4",
messages: [
{ role: "system", content: "Existing system prompt" },
{ role: "user", content: "Hello" },
],
stream: false,
});
});
it("should pass temperature and maxTokens as parameters", async () => {
const request: ChatRequestDto = {
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
temperature: 0.7,
maxTokens: 100,
};
mockOpenAiInstance.chat.completions.create.mockResolvedValue({
model: "gpt-4",
choices: [
{
message: { role: "assistant", content: "Hi!" },
finish_reason: "stop",
},
],
usage: { prompt_tokens: 10, completion_tokens: 2, total_tokens: 12 },
});
await provider.chat(request);
expect(mockOpenAiInstance.chat.completions.create).toHaveBeenCalledWith({
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
stream: false,
temperature: 0.7,
max_tokens: 100,
});
});
it("should throw error when chat fails", async () => {
const request: ChatRequestDto = {
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
};
mockOpenAiInstance.chat.completions.create.mockRejectedValue(
new Error("Model not available")
);
await expect(provider.chat(request)).rejects.toThrow("Chat completion failed");
});
});
describe("chatStream", () => {
it("should stream chat completion chunks", async () => {
const request: ChatRequestDto = {
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
};
const mockChunks = [
{
id: "chatcmpl-123",
object: "chat.completion.chunk",
created: 1677652288,
model: "gpt-4",
choices: [
{
index: 0,
delta: { role: "assistant", content: "Hello" },
finish_reason: null,
},
],
},
{
id: "chatcmpl-123",
object: "chat.completion.chunk",
created: 1677652288,
model: "gpt-4",
choices: [
{
index: 0,
delta: { content: "!" },
finish_reason: null,
},
],
},
{
id: "chatcmpl-123",
object: "chat.completion.chunk",
created: 1677652288,
model: "gpt-4",
choices: [
{
index: 0,
delta: {},
finish_reason: "stop",
},
],
},
];
// Mock async generator
async function* mockStreamGenerator() {
for (const chunk of mockChunks) {
yield chunk;
}
}
mockOpenAiInstance.chat.completions.create.mockResolvedValue(mockStreamGenerator());
const chunks = [];
for await (const chunk of provider.chatStream(request)) {
chunks.push(chunk);
}
expect(chunks).toHaveLength(3);
expect(chunks[0]).toEqual({
model: "gpt-4",
message: { role: "assistant", content: "Hello" },
done: false,
});
expect(chunks[1]).toEqual({
model: "gpt-4",
message: { role: "assistant", content: "!" },
done: false,
});
expect(chunks[2].done).toBe(true);
expect(mockOpenAiInstance.chat.completions.create).toHaveBeenCalledWith({
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
stream: true,
});
});
it("should pass options in streaming mode", async () => {
const request: ChatRequestDto = {
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
temperature: 0.5,
maxTokens: 50,
};
async function* mockStreamGenerator() {
yield {
model: "gpt-4",
choices: [{ delta: { role: "assistant", content: "Hi" }, finish_reason: "stop" }],
};
}
mockOpenAiInstance.chat.completions.create.mockResolvedValue(mockStreamGenerator());
const generator = provider.chatStream(request);
await generator.next();
expect(mockOpenAiInstance.chat.completions.create).toHaveBeenCalledWith({
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
stream: true,
temperature: 0.5,
max_tokens: 50,
});
});
it("should throw error when streaming fails", async () => {
const request: ChatRequestDto = {
model: "gpt-4",
messages: [{ role: "user", content: "Hello" }],
};
mockOpenAiInstance.chat.completions.create.mockRejectedValue(new Error("Stream error"));
const generator = provider.chatStream(request);
await expect(generator.next()).rejects.toThrow("Streaming failed");
});
});
describe("embed", () => {
it("should generate embeddings successfully", async () => {
const request: EmbedRequestDto = {
model: "text-embedding-ada-002",
input: ["Hello world", "Test embedding"],
};
const mockResponse = {
object: "list",
data: [
{
object: "embedding",
index: 0,
embedding: [0.1, 0.2, 0.3],
},
{
object: "embedding",
index: 1,
embedding: [0.4, 0.5, 0.6],
},
],
model: "text-embedding-ada-002",
usage: {
prompt_tokens: 10,
total_tokens: 10,
},
};
mockOpenAiInstance.embeddings.create.mockResolvedValue(mockResponse);
const response = await provider.embed(request);
expect(response).toEqual({
model: "text-embedding-ada-002",
embeddings: [
[0.1, 0.2, 0.3],
[0.4, 0.5, 0.6],
],
});
expect(mockOpenAiInstance.embeddings.create).toHaveBeenCalledWith({
model: "text-embedding-ada-002",
input: ["Hello world", "Test embedding"],
});
});
it("should handle single string input", async () => {
const request: EmbedRequestDto = {
model: "text-embedding-ada-002",
input: ["Single text"],
};
mockOpenAiInstance.embeddings.create.mockResolvedValue({
data: [{ embedding: [0.1, 0.2] }],
model: "text-embedding-ada-002",
usage: { prompt_tokens: 5, total_tokens: 5 },
});
await provider.embed(request);
expect(mockOpenAiInstance.embeddings.create).toHaveBeenCalledWith({
model: "text-embedding-ada-002",
input: ["Single text"],
});
});
it("should throw error when embedding fails", async () => {
const request: EmbedRequestDto = {
model: "text-embedding-ada-002",
input: ["Test"],
};
mockOpenAiInstance.embeddings.create.mockRejectedValue(new Error("Embedding error"));
await expect(provider.embed(request)).rejects.toThrow("Embedding failed");
});
});
describe("getConfig", () => {
it("should return copy of configuration", () => {
const returnedConfig = provider.getConfig();
expect(returnedConfig).toEqual(config);
expect(returnedConfig).not.toBe(config); // Should be a copy, not reference
});
it("should prevent external modification of config", () => {
const returnedConfig = provider.getConfig();
returnedConfig.apiKey = "sk-modified-key";
const secondCall = provider.getConfig();
expect(secondCall.apiKey).toBe("sk-test-1234567890"); // Original unchanged
});
it("should not expose API key in logs", () => {
const returnedConfig = provider.getConfig();
// API key should be present in config
expect(returnedConfig.apiKey).toBeDefined();
expect(returnedConfig.apiKey.length).toBeGreaterThan(0);
});
});
});

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import { Logger } from "@nestjs/common";
import OpenAI from "openai";
import type { ChatCompletionMessageParam } from "openai/resources/chat";
import type {
LlmProviderInterface,
LlmProviderConfig,
LlmProviderHealthStatus,
} from "./llm-provider.interface";
import type { ChatRequestDto, ChatResponseDto, EmbedRequestDto, EmbedResponseDto } from "../dto";
import { TraceLlmCall, createLlmSpan } from "../../telemetry";
import { SpanStatusCode } from "@opentelemetry/api";
/**
* Configuration for OpenAI LLM provider.
* Extends base LlmProviderConfig with OpenAI-specific options.
*
* @example
* ```typescript
* const config: OpenAiProviderConfig = {
* endpoint: "https://api.openai.com/v1",
* apiKey: "sk-...",
* organization: "org-...",
* timeout: 30000
* };
* ```
*/
export interface OpenAiProviderConfig extends LlmProviderConfig {
/**
* OpenAI API endpoint URL
* @default "https://api.openai.com/v1"
*/
endpoint: string;
/**
* OpenAI API key (required)
*/
apiKey: string;
/**
* Optional OpenAI organization ID
*/
organization?: string;
/**
* Request timeout in milliseconds
* @default 30000
*/
timeout?: number;
}
/**
* OpenAI LLM provider implementation.
* Provides integration with OpenAI's GPT models (GPT-4, GPT-3.5, etc.).
*
* @example
* ```typescript
* const provider = new OpenAiProvider({
* endpoint: "https://api.openai.com/v1",
* apiKey: "sk-...",
* timeout: 30000
* });
*
* await provider.initialize();
*
* const response = await provider.chat({
* model: "gpt-4",
* messages: [{ role: "user", content: "Hello" }]
* });
* ```
*/
export class OpenAiProvider implements LlmProviderInterface {
readonly name = "OpenAI";
readonly type = "openai" as const;
private readonly logger = new Logger(OpenAiProvider.name);
private readonly client: OpenAI;
private readonly config: OpenAiProviderConfig;
/**
* Creates a new OpenAI provider instance.
*
* @param config - OpenAI provider configuration
*/
constructor(config: OpenAiProviderConfig) {
this.config = {
...config,
timeout: config.timeout ?? 30000,
};
this.client = new OpenAI({
apiKey: this.config.apiKey,
organization: this.config.organization,
baseURL: this.config.endpoint,
timeout: this.config.timeout,
});
this.logger.log(`OpenAI provider initialized with endpoint: ${this.config.endpoint}`);
}
/**
* Initialize the OpenAI provider.
* This is a no-op for OpenAI as the client is initialized in the constructor.
*/
async initialize(): Promise<void> {
// OpenAI client is initialized in constructor
// No additional setup required
}
/**
* Check if the OpenAI API is healthy and reachable.
*
* @returns Health status with available models if healthy
*/
async checkHealth(): Promise<LlmProviderHealthStatus> {
try {
const response = await this.client.models.list();
const models = response.data.map((m) => m.id);
return {
healthy: true,
provider: "openai",
endpoint: this.config.endpoint,
models,
};
} catch (error: unknown) {
const errorMessage = error instanceof Error ? error.message : String(error);
this.logger.warn(`OpenAI health check failed: ${errorMessage}`);
return {
healthy: false,
provider: "openai",
endpoint: this.config.endpoint,
error: errorMessage,
};
}
}
/**
* List all available models from the OpenAI API.
*
* @returns Array of model names
* @throws {Error} If the request fails
*/
async listModels(): Promise<string[]> {
try {
const response = await this.client.models.list();
return response.data.map((m) => m.id);
} catch (error: unknown) {
const errorMessage = error instanceof Error ? error.message : String(error);
this.logger.error(`Failed to list models: ${errorMessage}`);
throw new Error(`Failed to list models: ${errorMessage}`);
}
}
/**
* Perform a synchronous chat completion.
*
* @param request - Chat request with messages and configuration
* @returns Complete chat response
* @throws {Error} If the request fails
*/
@TraceLlmCall({ system: "openai", operation: "chat" })
async chat(request: ChatRequestDto): Promise<ChatResponseDto> {
try {
const messages = this.buildMessages(request);
const options = this.buildChatOptions(request);
const response = await this.client.chat.completions.create({
model: request.model,
messages,
stream: false,
...options,
});
const choice = response.choices[0];
if (!choice) {
throw new Error("No completion choice returned from OpenAI");
}
const result: ChatResponseDto = {
model: response.model,
message: {
role: choice.message.role as "assistant",
content: choice.message.content ?? "",
},
done: true,
};
// Add optional properties only if they exist
if (response.usage?.prompt_tokens !== undefined) {
result.promptEvalCount = response.usage.prompt_tokens;
}
if (response.usage?.completion_tokens !== undefined) {
result.evalCount = response.usage.completion_tokens;
}
return result;
} catch (error: unknown) {
const errorMessage = error instanceof Error ? error.message : String(error);
this.logger.error(`Chat completion failed: ${errorMessage}`);
throw new Error(`Chat completion failed: ${errorMessage}`);
}
}
/**
* Perform a streaming chat completion.
* Yields response chunks as they arrive from the OpenAI API.
*
* @param request - Chat request with messages and configuration
* @yields Chat response chunks
* @throws {Error} If the request fails
*/
async *chatStream(request: ChatRequestDto): AsyncGenerator<ChatResponseDto> {
const span = createLlmSpan("openai", "chat.stream", request.model);
try {
const messages = this.buildMessages(request);
const options = this.buildChatOptions(request);
const stream = await this.client.chat.completions.create({
model: request.model,
messages,
stream: true,
...options,
});
for await (const chunk of stream) {
const choice = chunk.choices[0];
if (!choice) {
continue;
}
const isDone = choice.finish_reason === "stop" || choice.finish_reason === "length";
const role = choice.delta.role === "assistant" ? "assistant" : "assistant";
yield {
model: chunk.model,
message: {
role,
content: choice.delta.content ?? "",
},
done: isDone,
};
}
span.setStatus({ code: SpanStatusCode.OK });
} catch (error: unknown) {
const errorMessage = error instanceof Error ? error.message : String(error);
this.logger.error(`Streaming failed: ${errorMessage}`);
span.recordException(error instanceof Error ? error : new Error(errorMessage));
span.setStatus({
code: SpanStatusCode.ERROR,
message: errorMessage,
});
throw new Error(`Streaming failed: ${errorMessage}`);
} finally {
span.end();
}
}
/**
* Generate embeddings for the given input texts.
*
* @param request - Embedding request with model and input texts
* @returns Embeddings response with vector arrays
* @throws {Error} If the request fails
*/
@TraceLlmCall({ system: "openai", operation: "embed" })
async embed(request: EmbedRequestDto): Promise<EmbedResponseDto> {
try {
const response = await this.client.embeddings.create({
model: request.model,
input: request.input,
});
return {
model: response.model,
embeddings: response.data.map((item) => item.embedding),
};
} catch (error: unknown) {
const errorMessage = error instanceof Error ? error.message : String(error);
this.logger.error(`Embedding failed: ${errorMessage}`);
throw new Error(`Embedding failed: ${errorMessage}`);
}
}
/**
* Get the current provider configuration.
* Returns a copy to prevent external modification.
*
* @returns Provider configuration object
*/
getConfig(): OpenAiProviderConfig {
return { ...this.config };
}
/**
* Build message array from chat request.
* Prepends system prompt if provided and not already in messages.
*
* @param request - Chat request
* @returns Array of messages for OpenAI
*/
private buildMessages(request: ChatRequestDto): ChatCompletionMessageParam[] {
const messages: ChatCompletionMessageParam[] = [];
// Add system prompt if provided and not already in messages
if (request.systemPrompt && !request.messages.some((m) => m.role === "system")) {
messages.push({
role: "system",
content: request.systemPrompt,
});
}
// Add all request messages
for (const message of request.messages) {
messages.push({
role: message.role,
content: message.content,
});
}
return messages;
}
/**
* Build OpenAI-specific chat options from request.
*
* @param request - Chat request
* @returns OpenAI options object
*/
private buildChatOptions(request: ChatRequestDto): {
temperature?: number;
max_tokens?: number;
} {
const options: { temperature?: number; max_tokens?: number } = {};
if (request.temperature !== undefined) {
options.temperature = request.temperature;
}
if (request.maxTokens !== undefined) {
options.max_tokens = request.maxTokens;
}
return options;
}
}