Add support for custom provider

Author: NitayRabi

README.md

@@ -100,12 +100,29 @@ Create an RLLM instance with sensible defaults.
 ```typescript
 const rlm = createRLLM({
   model: 'gpt-4o-mini',      // Model name
-  provider: 'openai',         // 'openai' | 'anthropic' | 'openrouter'
+  provider: 'openai',         // 'openai' | 'anthropic' | 'openrouter' | 'custom'
   apiKey: process.env.KEY,    // Optional, uses env vars by default
+  baseUrl: undefined,         // Optional, required for 'custom' provider
   verbose: true,              // Enable logging
 });
 ```
 
+### Custom Provider (OpenAI-Compatible APIs)
+
+Use the `custom` provider to connect to any OpenAI-compatible API (e.g., vLLM, Ollama, LM Studio, Azure OpenAI):
+
+```typescript
+const rlm = createRLLM({
+  provider: 'custom',
+  model: 'llama-3.1-8b',
+  baseUrl: 'http://localhost:8000/v1',  // Required for custom provider
+  apiKey: 'your-api-key',               // Optional, depends on your API
+  verbose: true,
+});
+```
+
+**Note:** When using `provider: 'custom'`, the `baseUrl` parameter is **required**. An error will be thrown if it's not provided.
+
 ### `RLLM` Methods
 
 | Method | Description |

src/llm-client.test.ts

@@ -6,29 +6,34 @@
  */
 
 import { describe, it, expect } from "vitest";
+import { LLMClient } from "./llm-client.js";
 
 // Test the provider configuration logic directly
 // (extracted from LLMClient to make it testable)
 
-function getDefaultApiKey(provider: "openai" | "anthropic" | "openrouter"): string | undefined {
+function getDefaultApiKey(provider: "openai" | "anthropic" | "openrouter" | "custom"): string | undefined {
   switch (provider) {
     case "openai":
       return process.env["OPENAI_API_KEY"];
     case "anthropic":
       return process.env["ANTHROPIC_API_KEY"];
     case "openrouter":
       return process.env["OPENROUTER_API_KEY"];
+    case "custom":
+      return undefined;
   }
 }
 
-function getDefaultBaseUrl(provider: "openai" | "anthropic" | "openrouter"): string | undefined {
+function getDefaultBaseUrl(provider: "openai" | "anthropic" | "openrouter" | "custom"): string | undefined {
   switch (provider) {
     case "openai":
       return undefined; // Uses default
     case "anthropic":
       return "https://api.anthropic.com/v1";
     case "openrouter":
       return "https://openrouter.ai/api/v1";
+    case "custom":
+      return undefined;
   }
 }
 
@@ -74,5 +79,35 @@ describe("LLMClient provider configuration", () => {
 
       process.env["OPENROUTER_API_KEY"] = original;
     });
+
+    it("returns undefined for custom provider (must be provided explicitly)", () => {
+      expect(getDefaultApiKey("custom")).toBeUndefined();
+    });
+  });
+
+  describe("custom provider", () => {
+    it("returns undefined for custom provider base URL", () => {
+      expect(getDefaultBaseUrl("custom")).toBeUndefined();
+    });
+
+    it("throws error when custom provider is used without baseUrl", () => {
+      expect(() => {
+        new LLMClient({
+          provider: "custom",
+          model: "my-model",
+          apiKey: "test-key",
+        });
+      }).toThrow("Custom provider requires a baseUrl to be specified");
+    });
+
+    it("creates client successfully when custom provider has baseUrl", () => {
+      const client = new LLMClient({
+        provider: "custom",
+        model: "my-model",
+        apiKey: "test-key",
+        baseUrl: "https://my-custom-api.example.com/v1",
+      });
+      expect(client).toBeDefined();
+    });
   });
 });

src/llm-client.ts

@@ -42,6 +42,11 @@ export class LLMClient {
     this.model = options.model;
     this.provider = options.provider;
 
+    // Validate: custom provider requires baseUrl
+    if (options.provider === "custom" && !options.baseUrl) {
+      throw new Error("Custom provider requires a baseUrl to be specified");
+    }
+
     const apiKey = options.apiKey ?? this.getDefaultApiKey(options.provider);
     const baseUrl = options.baseUrl ?? this.getDefaultBaseUrl(options.provider);
 
@@ -56,6 +61,8 @@ export class LLMClient {
         return process.env["ANTHROPIC_API_KEY"];
       case "openrouter":
         return process.env["OPENROUTER_API_KEY"];
+      case "custom":
+        return undefined; // Must be provided explicitly
     }
   }
 
@@ -67,6 +74,8 @@ export class LLMClient {
         return "https://api.anthropic.com/v1";
       case "openrouter":
         return "https://openrouter.ai/api/v1";
+      case "custom":
+        return undefined; // Must be provided explicitly (validated in constructor)
     }
   }
 

src/rlm.ts

@@ -306,15 +306,17 @@ export class RLLM {
  */
 export function createRLLM(options: {
   model?: string;
-  provider?: "openai" | "anthropic" | "openrouter";
+  provider?: "openai" | "anthropic" | "openrouter" | "custom";
   apiKey?: string;
+  baseUrl?: string;
   verbose?: boolean;
 }): RLLM {
   return new RLLM({
     client: {
       provider: options.provider ?? "openai",
       model: options.model ?? "gpt-4o-mini",
       apiKey: options.apiKey,
+      baseUrl: options.baseUrl,
     },
     verbose: options.verbose,
   });

src/types.ts

@@ -23,7 +23,7 @@ export type InferContextType<S> = S extends ZodType<infer T> ? T : string;
 // LLM Client Types
 // ============================================================================
 
-export type LLMProvider = "openai" | "anthropic" | "openrouter";
+export type LLMProvider = "openai" | "anthropic" | "openrouter" | "custom";
 
 export interface ChatMessage {
   role: "system" | "user" | "assistant" | "tool";