diff --git a/packages/core/src/services/shellExecutionService.test.ts b/packages/core/src/services/shellExecutionService.test.ts
index 311dc4b91..12a9e0c34 100644
--- a/packages/core/src/services/shellExecutionService.test.ts
+++ b/packages/core/src/services/shellExecutionService.test.ts
@@ -73,7 +73,6 @@ vi.mock('../utils/shell-utils.js', () => ({
 vi.mock('../utils/systemEncoding.js', () => ({
   getCachedEncodingForBuffer: vi.fn().mockReturnValue('utf-8'),
   getSystemEncoding: mockGetSystemEncoding,
-  WINDOWS_UTF8_CODE_PAGE: 65001,
 }));
 
 const mockProcessKill = vi
diff --git a/packages/core/src/utils/systemEncoding.ts b/packages/core/src/utils/systemEncoding.ts
index fd12ff614..b0a45c02a 100644
--- a/packages/core/src/utils/systemEncoding.ts
+++ b/packages/core/src/utils/systemEncoding.ts
@@ -47,6 +47,13 @@ export function getCachedEncodingForBuffer(buffer: Buffer): string {
     return detected;
   }
 
+  if (cachedSystemEncoding === undefined) {
+    cachedSystemEncoding = getSystemEncoding();
+  }
+  if (cachedSystemEncoding) {
+    return cachedSystemEncoding;
+  }
+
   // Last resort
   return 'utf-8';
 }
@@ -134,8 +141,6 @@ export function getSystemEncoding(): string | null {
  * @param cp The Windows code page number (e.g., 437, 850, etc.)
  * @returns The corresponding encoding name as a string, or null if no mapping exists.
  */
-/** Windows code page number for UTF-8. */
-export const WINDOWS_UTF8_CODE_PAGE = 65001;
 
 export function windowsCodePageToEncoding(cp: number): string | null {
   // Most common mappings; extend as needed
@@ -160,7 +165,7 @@ export function windowsCodePageToEncoding(cp: number): string | null {
     1256: 'windows-1256',
     1257: 'windows-1257',
     1258: 'windows-1258',
-    [WINDOWS_UTF8_CODE_PAGE]: 'utf-8',
+    65001: 'utf-8',
   };
 
   if (map[cp]) {
@@ -192,14 +197,5 @@ export function detectEncodingFromBuffer(buffer: Buffer): string | null {
     debugLogger.warn('Failed to detect encoding with chardet:', error);
   }
 
-  // Fall back to system encoding — catches cases where chardet fails
-  // (e.g. small GBK files that chardet misdetects as ISO-8859-2)
-  if (cachedSystemEncoding === undefined) {
-    cachedSystemEncoding = getSystemEncoding();
-  }
-  if (cachedSystemEncoding) {
-    return cachedSystemEncoding;
-  }
-
   return null;
 }