fix: passing right llm setting from SimpleChatEngine to ChatMemoryBuffer (#1798)

.changeset/gorgeous-pigs-sneeze.md

@@ -0,0 +1,5 @@
+---
+"@llamaindex/core": patch
+---
+
+Fix passing right llm setting from SimpleChatEngine to ChatMemoryBuffer

packages/core/src/chat-engine/simple-chat-engine.ts

@@ -24,8 +24,12 @@ export class SimpleChatEngine implements BaseChatEngine {
   }
 
   constructor(init?: Partial<SimpleChatEngine>) {
-    this.memory = init?.memory ?? new ChatMemoryBuffer();
     this.llm = init?.llm ?? Settings.llm;
+    this.memory =
+      init?.memory ??
+      new ChatMemoryBuffer({
+        llm: this.llm,
+      });
   }
 
   chat(params: NonStreamingChatEngineParams): Promise<EngineResponse>;
@@ -40,6 +44,7 @@ export class SimpleChatEngine implements BaseChatEngine {
 
     const chatHistory = params.chatHistory
       ? new ChatMemoryBuffer({
+          llm: this.llm,
           chatHistory:
             params.chatHistory instanceof BaseMemory
               ? await params.chatHistory.getMessages()

packages/core/tests/simple-chat-engine.test.ts

@@ -0,0 +1,14 @@
+import { SimpleChatEngine } from "@llamaindex/core/chat-engine";
+import { ChatMemoryBuffer } from "@llamaindex/core/memory";
+import { MockLLM } from "@llamaindex/core/utils";
+import { describe, expect, test } from "vitest";
+
+describe("SimpleChatEngine", () => {
+  test("constructor initializes with provided LLM", () => {
+    const llm = new MockLLM();
+    const engine = new SimpleChatEngine({ llm });
+    expect(engine.llm).toBe(llm);
+    expect(engine.memory).toBeInstanceOf(ChatMemoryBuffer);
+    expect((engine.memory as ChatMemoryBuffer).tokenLimit).toBe(768);
+  });
+});