diff --git a/src/config/index.ts b/src/config/index.ts
index 97d4937..860776b 100644
--- a/src/config/index.ts
+++ b/src/config/index.ts
@@ -2,9 +2,20 @@ import type { DomConfig } from '@/dom'
 import type { SupportedLanguage } from '@/i18n'
 import type { LLMConfig } from '@/llms'
 
+import { DEFAULT_API_KEY, DEFAULT_BASE_URL, DEFAULT_MODEL_NAME, LLM_MAX_RETRIES } from './constants'
+
 export interface UIConfig {
 	// theme?: 'light' | 'dark'
 	language?: SupportedLanguage
 }
 
 export type PageAgentConfig = LLMConfig & DomConfig & UIConfig
+
+export function parseLLMConfig(config: LLMConfig): Required<LLMConfig> {
+	return {
+		baseURL: config.baseURL ?? DEFAULT_BASE_URL,
+		apiKey: config.apiKey ?? DEFAULT_API_KEY,
+		modelName: config.modelName ?? DEFAULT_MODEL_NAME,
+		maxRetries: config.maxRetries ?? LLM_MAX_RETRIES,
+	}
+}
diff --git a/src/entry.ts b/src/entry.ts
index 2b353ba..c771685 100644
--- a/src/entry.ts
+++ b/src/entry.ts
@@ -2,7 +2,6 @@
  * Auto-run entry for page-agent.js. Insert this script into your page to get page-agent functionality.
  */
 import { PageAgent, type PageAgentConfig } from './PageAgent'
-import { DEFAULT_MODEL_NAME } from './config/constants'
 
 // Clean up existing instances to prevent multiple injections from bookmarklet
 if (window.pageAgent) {
@@ -20,7 +19,7 @@ console.log('🚀 page-agent.js loaded!')
 const currentScript = document.currentScript as HTMLScriptElement | null
 if (currentScript) {
 	const url = new URL(currentScript.src)
-	const modelName = url.searchParams.get('model') || DEFAULT_MODEL_NAME
+	const modelName = url.searchParams.get('model')
 	const language = (url.searchParams.get('lang') as 'zh-CN' | 'en-US') || 'zh-CN'
 	const config = { modelName, language } as PageAgentConfig
 	window.pageAgent = new PageAgent(config)
diff --git a/src/llms/index.ts b/src/llms/index.ts
index 81ba965..caa2dff 100644
--- a/src/llms/index.ts
+++ b/src/llms/index.ts
@@ -37,13 +37,8 @@ import type { LanguageModelUsage, ModelMessage, TypedToolCall, TypedToolResult }
 import { ToolSet, generateText, stepCountIs } from 'ai'
 import chalk from 'chalk'
 
-import {
-	DEFAULT_API_KEY,
-	DEFAULT_BASE_URL,
-	DEFAULT_MODEL_NAME,
-	LLM_MAX_RETRIES,
-	MACRO_TOOL_NAME,
-} from '@/config/constants'
+import { parseLLMConfig } from '@/config'
+import { MACRO_TOOL_NAME } from '@/config/constants'
 import { assert } from '@/utils/assert'
 import { EventBus, getEventBus } from '@/utils/bus'
 
@@ -62,13 +57,7 @@ export class LLM {
 	#bus: EventBus
 
 	constructor(config: LLMConfig, id: string) {
-		this.config = {
-			baseURL: DEFAULT_BASE_URL,
-			apiKey: DEFAULT_API_KEY,
-			modelName: DEFAULT_MODEL_NAME,
-			maxRetries: LLM_MAX_RETRIES,
-			...config,
-		}
+		this.config = parseLLMConfig(config)
 		this.id = id
 
 		this.#bus = getEventBus(id)