feat: add OpenRouter API client with free model support

app/lib/__tests__/openrouter.test.ts

@@ -0,0 +1,26 @@
+import { describe, it, expect } from "vitest";
+import { OpenRouterClient } from "../openrouter";
+
+describe("OpenRouterClient", () => {
+  it("should create instance with API key", () => {
+    const client = new OpenRouterClient("test-api-key");
+    expect(client).toBeInstanceOf(OpenRouterClient);
+  });
+
+  it("should have default free models list", () => {
+    const client = new OpenRouterClient("test-api-key");
+    const models = client.getFreeModels();
+    expect(models).toContain("google/gemini-2.0-flash-exp:free");
+  });
+
+  it("should have available model providers", () => {
+    const client = new OpenRouterClient("test-api-key");
+    const providers = client.getProviders();
+    expect(providers).toContain("openai");
+    expect(providers).toContain("google");
+    expect(providers).toContain("anthropic");
+    expect(providers).toContain("deepseek");
+    expect(providers).toContain("meta");
+    expect(providers).toContain("xai");
+  });
+});

app/lib/openrouter.ts

@@ -0,0 +1,60 @@
+type Message = {
+  role: "system" | "user" | "assistant";
+  content: string;
+};
+
+type OpenRouterConfig = {
+  baseURL?: string;
+  defaultModel?: string;
+};
+
+export class OpenRouterClient {
+  private apiKey: string;
+  private baseURL: string;
+  private defaultModel: string;
+  private freeModels = [
+    "google/gemini-2.0-flash-exp:free",
+    "deepseek/deepseek-chat:free",
+    "meta/llama-3.3-70b-instruct:free",
+  ];
+  private providers = ["openai", "google", "anthropic", "deepseek", "meta", "xai"];
+
+  constructor(apiKey: string, config?: OpenRouterConfig) {
+    this.apiKey = apiKey;
+    this.baseURL = config?.baseURL ?? "https://openrouter.ai/api/v1";
+    this.defaultModel = config?.defaultModel ?? "google/gemini-2.0-flash-exp:free";
+  }
+
+  getFreeModels(): string[] {
+    return [...this.freeModels];
+  }
+
+  getProviders(): string[] {
+    return [...this.providers];
+  }
+
+  async createChatCompletion(
+    messages: Message[],
+    model?: string
+  ): Promise<unknown> {
+    const response = await fetch(`${this.baseURL}/chat/completions`, {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+        Authorization: `Bearer ${this.apiKey}`,
+        "HTTP-Referer": "https://aitrader.local",
+        "X-Title": "AITrader",
+      },
+      body: JSON.stringify({
+        model: model ?? this.defaultModel,
+        messages,
+      }),
+    });
+
+    if (!response.ok) {
+      throw new Error(`OpenRouter API error: ${response.status}`);
+    }
+
+    return response.json();
+  }
+}