diff --git a/src/language-model.ts b/src/language-model.ts
index 9b5477c..063e66f 100644
--- a/src/language-model.ts
+++ b/src/language-model.ts
@@ -6,7 +6,6 @@ import {
   LanguageModelV1FunctionToolCall,
   LanguageModelV1ImagePart,
   LanguageModelV1LogProbs,
-  LanguageModelV1Message,
   LanguageModelV1Prompt,
   LanguageModelV1StreamPart,
   LanguageModelV1TextPart,
@@ -35,6 +34,7 @@ export interface ChromeAIChatSettings extends Record<string, unknown> {
 
   /**
    * Optional. A list of unique safety settings for blocking unsafe content.
+   * @note this is not working yet
    */
   safetySettings?: Array<{
     category:
@@ -60,13 +60,13 @@ function getStringContent(
     | LanguageModelV1ToolResultPart[]
 ): string {
   if (typeof content === 'string') {
-    return content;
+    return content.trim();
   } else if (Array.isArray(content) && content.length > 0) {
     const [first] = content;
     if (first.type !== 'text') {
       throw new UnsupportedFunctionalityError({ functionality: 'toolCall' });
     }
-    return first.text;
+    return first.text.trim();
   } else {
     return '';
   }
@@ -122,55 +122,53 @@ export class ChromeAIChatLanguageModel implements LanguageModelV1 {
     return this.session;
   };
 
-  private magicPrompts: Record<
-    LanguageModelV1CallOptions['mode']['type'],
-    string | null
-  > = {
-    regular: null,
-    'object-grammar': null,
-    'object-tool': null,
-    'object-json':
-      'Always response pure json string format that matches the JSON schema above, not markdown or other format!!',
-  };
-  private roleMap: Record<LanguageModelV1Message['role'], string> = {
-    system: 'system',
-    user: 'user',
-    tool: 'user',
-    assistant: 'model',
-  };
-
   private formatMessages = (options: LanguageModelV1CallOptions): string => {
     let prompt: LanguageModelV1Prompt = options.prompt;
+    debug('before format prompt:', prompt);
+
+    let result = '';
 
-    // When the user supplied a prompt input, we don't transform it:
     if (
+      // When the user supplied a prompt input, we don't transform it
       options.inputFormat === 'prompt' &&
       prompt.length === 1 &&
       prompt[0].role === 'user' &&
       prompt[0].content.length === 1 &&
       prompt[0].content[0].type === 'text'
     ) {
-      debug('formated message:', prompt[0].content[0].text);
-      return prompt[0].content[0].text;
-    }
+      result += prompt[0].content[0].text;
+    } else {
+      // Use magic prompt for object-json mode
+      if (options.mode.type === 'object-json') {
+        prompt.unshift({
+          role: 'system',
+          content: `Throughout our conversation, always start your responses with "{" and end with "}", ensuring the output is a concise JSON object and strictly avoid including any comments, notes, explanations, or examples in your output.\nFor instance, if the JSON schema is {"type":"object","properties":{"someKey":{"type":"string"}},"required":["someKey"],"additionalProperties":false,"$schema":"http://json-schema.org/draft-07/schema#"}, your response should immediately begin with "{" and strictly end with "}", following the format: {"someKey": "someValue"}.\nAdhere to this format for all queries moving forward.`,
+        });
+      }
+
+      for (let index = 0; index < prompt.length; index += 1) {
+        const { role, content } = prompt[index];
+        const contentString = getStringContent(content);
 
-    // FIXME: something tricky here
-    if (this.magicPrompts[options.mode.type]) {
-      prompt = [
-        { role: 'system', content: this.magicPrompts[options.mode.type]! },
-        ...prompt,
-      ];
+        switch (role) {
+          case 'system':
+            result += `${contentString}\n`;
+            break;
+          case 'assistant':
+          case 'tool':
+            result += `model\n${contentString}\n`;
+            break;
+          case 'user':
+          default:
+            result += `user\n${contentString}\n`;
+            break;
+        }
+      }
+      result += `model\n`;
     }
 
-    const messages = prompt
-      .map(
-        ({ role, content }) =>
-          `${this.roleMap[role]}:\n${getStringContent(content)}`
-      )
-      .join('\n\n');
-    debug('format prompt:', prompt);
-    debug('formated message:', messages);
-    return messages + `\n`;
+    debug('formated message:', result);
+    return result;
   };
 
   public doGenerate = async (
@@ -185,10 +183,17 @@ export class ChromeAIChatLanguageModel implements LanguageModelV1 {
     warnings?: LanguageModelV1CallWarning[];
     logprobs?: LanguageModelV1LogProbs;
   }> => {
-    const session = await this.getSession({ temperature: options.temperature });
+    debug('generate options:', options);
+
+    if (['regular', 'object-json'].indexOf(options.mode.type) < 0) {
+      throw new UnsupportedFunctionalityError({
+        functionality: `${options.mode.type} mode`,
+      });
+    }
+
+    const session = await this.getSession();
     const message = this.formatMessages(options);
     const text = await session.prompt(message);
-    debug('generate options:', options);
     debug('generate result:', text);
     return {
       text,
@@ -206,16 +211,26 @@ export class ChromeAIChatLanguageModel implements LanguageModelV1 {
     rawResponse?: { headers?: Record<string, string> };
     warnings?: LanguageModelV1CallWarning[];
   }> => {
-    const session = await this.getSession({ temperature: options.temperature });
+    debug('stream options:', options);
+
+    if (['regular'].indexOf(options.mode.type) < 0) {
+      throw new UnsupportedFunctionalityError({
+        functionality: `${options.mode.type} mode`,
+      });
+    }
+
+    const session = await this.getSession();
     const message = this.formatMessages(options);
     const promptStream = session.promptStreaming(message);
-    debug('stream options:', options);
+
+    let tempResult = '';
     const transformStream = new TransformStream<
       string,
       LanguageModelV1StreamPart
     >({
       transform(textDelta, controller) {
         controller.enqueue({ type: 'text-delta', textDelta });
+        tempResult = textDelta;
       },
       flush(controller) {
         controller.enqueue({
@@ -223,7 +238,8 @@ export class ChromeAIChatLanguageModel implements LanguageModelV1 {
           finishReason: 'stop',
           usage: { completionTokens: 0, promptTokens: 0 },
         });
-        controller.terminate();
+        debug('stream result:', tempResult);
+        tempResult = '';
       },
     });
     const stream = promptStream.pipeThrough(transformStream);