更新配置和聊天路由，添加会话中止与分叉功能

src/runtime/opencode.ts

@@ -46,20 +46,38 @@ export class OpencodeRuntimeAdapter {
   }
 
   async sendPrompt(sessionId: string, text: string) {
+    await this.prompt(sessionId, text);
+    // 当前 SDK 响应风格下，prompt() 本身不会直接返回完整 assistant parts，
+    // 所以这里紧跟一次 messages() 回读，给上层路由统一消费。
+    return this.messages(sessionId);
+  }
+
+  async prompt(sessionId: string, text: string) {
     const client = await this.ensureClient();
     await client.session.prompt({
       sessionID: sessionId,
       parts: [{ type: "text", text }],
     });
-    // 当前 SDK 响应风格下，prompt() 本身不会直接返回完整 assistant parts，
-    // 所以这里紧跟一次 messages() 回读，给上层路由统一消费。
+  }
+
+  async messages(sessionId: string, limit = 20) {
+    const client = await this.ensureClient();
     const messages = await client.session.messages({
       sessionID: sessionId,
-      limit: 20,
+      limit,
     });
     return requireData(messages.data, "session.messages");
   }
 
+  async forkSession(sessionId: string, messageId?: string) {
+    const client = await this.ensureClient();
+    const response = await client.session.fork({
+      sessionID: sessionId,
+      messageID: messageId,
+    });
+    return requireData(response.data, "session.fork");
+  }
+
   async abortSession(sessionId: string) {
     const client = await this.ensureClient();
     const response = await client.session.abort({