diff --git a/package.json b/package.json
index dc20316..02204f6 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "g1nation",
   "displayName": "G1nation",
   "description": "High-performance autonomous local AI coding agent for VS Code. Features vectorized inference, asynchronous task management, and 100% offline processing.",
-  "version": "2.47.0",
+  "version": "2.48.0",
   "publisher": "connectailab",
   "license": "MIT",
   "icon": "assets/icon.png",
diff --git a/src/agent.ts b/src/agent.ts
index 87800fd..a55edd9 100644
--- a/src/agent.ts
+++ b/src/agent.ts
@@ -301,7 +301,7 @@ export class AgentExecutor {
             // 3. API Request Setup
             const { ollamaUrl, defaultModel: configDefaultModel, timeout } = getConfig();
             const actualModel = modelName || configDefaultModel;
-            const reqMessages = [...this.chatHistory];
+            const reqMessages = this.buildRequestHistory(this.chatHistory);
 
             // Handle Vision Content Injection
             // Merge text prompt with file content instead of replacing, so the user's message is never lost
@@ -773,6 +773,30 @@ export class AgentExecutor {
         return /(아키텍처|구조|조사|분석|설계|흐름|모듈|역할|개선|architecture|structure|design|flow|module|investigate|analy[sz]e)/i.test(prompt);
     }
 
+    private buildRequestHistory(history: ChatMessage[]): ChatMessage[] {
+        return history.map((message) => {
+            if (message.role !== 'assistant' || typeof message.content !== 'string') {
+                return message;
+            }
+
+            return {
+                ...message,
+                content: this.sanitizeHistoryAssistantContent(message.content)
+            };
+        });
+    }
+
+    private sanitizeHistoryAssistantContent(content: string): string {
+        return content
+            .replace(/<details>\s*<summary>2nd Brain Trace:[\s\S]*?<\/details>/gi, '')
+            .replace(/## Second Brain Debug JSON[\s\S]*?(?=\n## |\n# |$)/gi, '')
+            .replace(/## Candidate records for this discussion[\s\S]*?(?=\n## |\n# |$)/gi, '')
+            .replace(/## 후보 기록[\s\S]*?(?=\n## |\n# |$)/gi, '')
+            .replace(/## 프로젝트 기록 검토[\s\S]*?(?=\n## |\n# |$)/gi, '')
+            .replace(/\n{3,}/g, '\n\n')
+            .trim();
+    }
+
     private buildRecentProjectKnowledgeContext(prompt: string, rootPath: string): string {
         if (!rootPath || !this.isProjectKnowledgeFollowupRequest(prompt)) {
             return '';
diff --git a/tests/localPathPreflight.test.ts b/tests/localPathPreflight.test.ts
index f019ee4..340d66c 100644
--- a/tests/localPathPreflight.test.ts
+++ b/tests/localPathPreflight.test.ts
@@ -204,4 +204,35 @@ describe('local project path preflight', () => {
         expect(followup).toContain('src/agent.ts');
         expect(followup).toContain('recently generated project knowledge record');
     });
+
+    it('removes old Second Brain trace details from assistant history before model requests', () => {
+        const context: any = {
+            globalStorageUri: { fsPath: path.join(root, '.storage') },
+            workspaceState: stateStore(),
+            globalState: stateStore()
+        };
+        const agent = new AgentExecutor(context) as any;
+        const history = [
+            { role: 'user', content: 'ConnectAI 지식 만들어줘' },
+            {
+                role: 'assistant',
+                content: [
+                    '## 간단 요약',
+                    'ConnectAI 프로젝트 지식을 만들었습니다.',
+                    '<details>',
+                    '<summary>2nd Brain Trace: 사용함</summary>',
+                    'Project_Logs/2026-04-25-Datacollector_Fix.md',
+                    '## Second Brain Debug JSON',
+                    '{"path":"Datacollector"}',
+                    '</details>'
+                ].join('\n')
+            }
+        ];
+
+        const requestHistory = agent.buildRequestHistory(history);
+
+        expect(requestHistory[1].content).toContain('ConnectAI 프로젝트 지식을 만들었습니다');
+        expect(requestHistory[1].content).not.toContain('Datacollector');
+        expect(requestHistory[1].content).not.toContain('2nd Brain Trace');
+    });
 });