Add dify as a provider

src/server/handler.ts

@@ -1,12 +1,14 @@
 import type { Message } from "../types";
 import { AnthropicProvider } from "./providers/anthropic";
+import { DifyProvider } from "./providers/dify";
 import { OpenAIProvider } from "./providers/openai";
 import type { LLMProvider, Middleware } from "./providers/types";
 
 export type AssistantConfig = {
-  provider: "anthropic" | "openai" | LLMProvider;
+  provider: "anthropic" | "openai" | "dify" | LLMProvider;
   apiKey?: string;
   model?: string;
+  baseUrl?: string;
   systemPrompt?: string;
   middleware?: Middleware[];
 };
@@ -105,6 +107,8 @@ function createProvider(config: AssistantConfig): LLMProvider {
       return new AnthropicProvider({ apiKey: config.apiKey, model: config.model });
     case "openai":
       return new OpenAIProvider({ apiKey: config.apiKey, model: config.model });
+    case "dify":
+      return new DifyProvider({ apiKey: config.apiKey, baseUrl: config.baseUrl });
     default:
       throw new Error(`Unknown provider: ${config.provider}`);
   }

src/server/index.ts

@@ -1,5 +1,6 @@
 export { createAssistant } from "./handler";
 export type { AssistantConfig } from "./handler";
 export { AnthropicProvider } from "./providers/anthropic";
+export { DifyProvider } from "./providers/dify";
 export { OpenAIProvider } from "./providers/openai";
 export type { LLMProvider, ProviderConfig, Middleware } from "./providers/types";

src/server/providers/dify.ts

@@ -0,0 +1,66 @@
+import type { Message } from "../../types";
+import type { LLMProvider, ProviderConfig } from "./types";
+
+export class DifyProvider implements LLMProvider {
+  private apiKey: string;
+  private baseUrl: string;
+
+  constructor(config: ProviderConfig) {
+    this.apiKey = config.apiKey;
+    if (!config.baseUrl) {
+      throw new Error("baseUrl is required for the Dify provider");
+    }
+    this.baseUrl = config.baseUrl.replace(/\/+$/, "");
+  }
+
+  async chat(messages: Message[], systemPrompt?: string): Promise<string> {
+    const query = this.buildQuery(messages, systemPrompt);
+
+    const response = await fetch(`${this.baseUrl}/v1/chat-messages`, {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+        Authorization: `Bearer ${this.apiKey}`,
+      },
+      body: JSON.stringify({
+        inputs: {},
+        query,
+        response_mode: "blocking",
+        user: "explain-user",
+      }),
+    });
+
+    if (!response.ok) {
+      const text = await response.text();
+      throw new Error(`Dify API error ${response.status}: ${text}`);
+    }
+
+    const data = await response.json();
+    if (!data.answer) {
+      throw new Error("No answer in Dify response");
+    }
+    return data.answer;
+  }
+
+  private buildQuery(messages: Message[], systemPrompt?: string): string {
+    const parts: string[] = [];
+
+    if (systemPrompt) {
+      parts.push(`[System]: ${systemPrompt}`);
+    }
+
+    for (const m of messages) {
+      if (m.role === "context") {
+        parts.push(`[Context]: ${m.content}`);
+      } else if (m.role === "system") {
+        parts.push(`[System]: ${m.content}`);
+      } else if (m.role === "assistant") {
+        parts.push(`[Assistant]: ${m.content}`);
+      } else {
+        parts.push(m.content);
+      }
+    }
+
+    return parts.join("\n\n");
+  }
+}

src/server/providers/types.ts

@@ -7,6 +7,7 @@ export interface LLMProvider {
 export type ProviderConfig = {
   apiKey: string;
   model?: string;
+  baseUrl?: string;
 };
 
 /**