fix: Do not reload model for summarization tasks

app/client/webllm.ts

@@ -80,37 +80,12 @@ export class WebLLMApi implements LLMApi {
     );
   }
 
-  async chatCompletion(
-    stream: boolean,
-    messages: RequestMessage[],
-    onUpdate?: (message: string, chunk: string) => void,
-  ) {
-    let reply: string | null = "";
-
-    const completion = await this.engine!.chatCompletion({
-      stream: stream,
-      messages: messages as ChatCompletionMessageParam[],
-    });
-
-    if (stream) {
-      const asyncGenerator = completion as AsyncIterable<ChatCompletionChunk>;
-      for await (const chunk of asyncGenerator) {
-        if (chunk.choices[0].delta.content) {
-          reply += chunk.choices[0].delta.content;
-          onUpdate?.(reply, chunk.choices[0].delta.content);
-        }
-      }
-      return reply;
-    }
-    return (completion as ChatCompletion).choices[0].message.content;
-  }
-
   async chat(options: ChatOptions): Promise<void> {
     // in case the service worker is dead, revive it by firing a fetch event
     fetch("/ping.txt");
 
-    if (this.isConfigChanged(options.config)) {
-      this.llmConfig = options.config;
+    if (this.isDifferentConfig(options.config)) {
+      this.llmConfig = { ...(this.llmConfig || {}), ...options.config };
       try {
         await this.initModel(options.onUpdate);
       } catch (e) {
@@ -157,6 +132,63 @@ export class WebLLMApi implements LLMApi {
       total: 0,
     };
   }
+
+  isDifferentConfig(config: LLMConfig): boolean {
+    if (!this.llmConfig) {
+      return true;
+    }
+
+    // Compare required fields
+    if (this.llmConfig.model !== config.model) {
+      return true;
+    }
+
+    // Compare optional fields
+    const optionalFields: (keyof LLMConfig)[] = [
+      "temperature",
+      "top_p",
+      "stream",
+      "presence_penalty",
+      "frequency_penalty",
+    ];
+
+    for (const field of optionalFields) {
+      if (
+        this.llmConfig[field] !== undefined &&
+        config[field] !== undefined &&
+        config[field] !== config[field]
+      ) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  async chatCompletion(
+    stream: boolean,
+    messages: RequestMessage[],
+    onUpdate?: (message: string, chunk: string) => void,
+  ) {
+    let reply: string | null = "";
+
+    const completion = await this.engine!.chatCompletion({
+      stream: stream,
+      messages: messages as ChatCompletionMessageParam[],
+    });
+
+    if (stream) {
+      const asyncGenerator = completion as AsyncIterable<ChatCompletionChunk>;
+      for await (const chunk of asyncGenerator) {
+        if (chunk.choices[0].delta.content) {
+          reply += chunk.choices[0].delta.content;
+          onUpdate?.(reply, chunk.choices[0].delta.content);
+        }
+      }
+      return reply;
+    }
+    return (completion as ChatCompletion).choices[0].message.content;
+  }
 }
 
 export const WebLLMContext = createContext<WebLLMApi | null>(null);