diff --git a/src/renderer/src/components/CodeEditor/__tests__/utils.test.ts b/src/renderer/src/components/CodeEditor/__tests__/utils.test.ts
new file mode 100644
index 0000000000..b02d10e152
--- /dev/null
+++ b/src/renderer/src/components/CodeEditor/__tests__/utils.test.ts
@@ -0,0 +1,43 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import { getNormalizedExtension } from '../utils'
+
+const mocks = vi.hoisted(() => ({
+  getExtensionByLanguage: vi.fn()
+}))
+
+vi.mock('@renderer/utils/code-language', () => ({
+  getExtensionByLanguage: mocks.getExtensionByLanguage
+}))
+
+describe('getNormalizedExtension', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  it('should return custom mapping for custom language', async () => {
+    mocks.getExtensionByLanguage.mockReturnValue(undefined)
+    await expect(getNormalizedExtension('svg')).resolves.toBe('xml')
+    await expect(getNormalizedExtension('SVG')).resolves.toBe('xml')
+  })
+
+  it('should prefer custom mapping when both custom and linguist exist', async () => {
+    mocks.getExtensionByLanguage.mockReturnValue('.svg')
+    await expect(getNormalizedExtension('svg')).resolves.toBe('xml')
+  })
+
+  it('should return linguist mapping when available (strip leading dot)', async () => {
+    mocks.getExtensionByLanguage.mockReturnValue('.ts')
+    await expect(getNormalizedExtension('TypeScript')).resolves.toBe('ts')
+  })
+
+  it('should return extension when input already looks like extension (leading dot)', async () => {
+    mocks.getExtensionByLanguage.mockReturnValue(undefined)
+    await expect(getNormalizedExtension('.json')).resolves.toBe('json')
+  })
+
+  it('should return language as-is when no rules matched', async () => {
+    mocks.getExtensionByLanguage.mockReturnValue(undefined)
+    await expect(getNormalizedExtension('unknownLanguage')).resolves.toBe('unknownLanguage')
+  })
+})
diff --git a/src/renderer/src/components/CodeEditor/hooks.ts b/src/renderer/src/components/CodeEditor/hooks.ts
index 7917cebd80..b6689644e9 100644
--- a/src/renderer/src/components/CodeEditor/hooks.ts
+++ b/src/renderer/src/components/CodeEditor/hooks.ts
@@ -8,7 +8,9 @@ import { getNormalizedExtension } from './utils'
 
 const logger = loggerService.withContext('CodeEditorHooks')
 
-// 语言对应的 linter 加载器
+/** 语言对应的 linter 加载器
+ * key: 语言文件扩展名（不包含 `.`）
+ */
 const linterLoaders: Record<string, () => Promise<any>> = {
   json: async () => {
     const jsonParseLinter = await import('@codemirror/lang-json').then((mod) => mod.jsonParseLinter)
@@ -64,13 +66,15 @@ async function loadLanguageExtension(language: string): Promise<Extension | null
  * 加载 linter 扩展
  */
 async function loadLinterExtension(language: string): Promise<Extension | null> {
-  const loader = linterLoaders[language]
+  const fileExt = await getNormalizedExtension(language)
+
+  const loader = linterLoaders[fileExt]
   if (!loader) return null
 
   try {
     return await loader()
   } catch (error) {
-    logger.debug(`Failed to load linter for ${language}`, error as Error)
+    logger.debug(`Failed to load linter for ${language} (${fileExt})`, error as Error)
     return null
   }
 }
diff --git a/src/renderer/src/components/CodeEditor/index.tsx b/src/renderer/src/components/CodeEditor/index.tsx
index 749ec57b01..7c541cbdb8 100644
--- a/src/renderer/src/components/CodeEditor/index.tsx
+++ b/src/renderer/src/components/CodeEditor/index.tsx
@@ -20,7 +20,13 @@ export interface CodeEditorProps {
   value: string
   /** Placeholder when the editor content is empty. */
   placeholder?: string | HTMLElement
-  /** Code language, supports aliases. */
+  /**
+   * Code language string.
+   * - Case-insensitive.
+   * - Supports common names: javascript, json, python, etc.
+   * - Supports aliases: c#/csharp, objective-c++/obj-c++/objc++, etc.
+   * - Supports file extensions: .cpp/cpp, .js/js, .py/py, etc.
+   */
   language: string
   /** Fired when ref.save() is called or the save shortcut is triggered. */
   onSave?: (newContent: string) => void
diff --git a/src/renderer/src/components/CodeEditor/utils.ts b/src/renderer/src/components/CodeEditor/utils.ts
index 251778b9d1..ef5941720e 100644
--- a/src/renderer/src/components/CodeEditor/utils.ts
+++ b/src/renderer/src/components/CodeEditor/utils.ts
@@ -13,6 +13,7 @@ const _customLanguageExtensions: Record<string, string> = {
  * 获取语言的扩展名，用于 @uiw/codemirror-extensions-langs
  * - 先搜索自定义扩展名
  * - 再搜索 github linguist 扩展名
+ * - 最后假定名称已经是扩展名
  * @param language 语言名称
  * @returns 扩展名（不包含 `.`）
  */
@@ -29,6 +30,11 @@ export async function getNormalizedExtension(language: string) {
     return linguistExt.slice(1)
   }
 
+  // 如果语言名称像扩展名
+  if (language.startsWith('.') && language.length > 1) {
+    return language.slice(1)
+  }
+
   // 回退到语言名称
   return language
 }