fix: character encoding issues in shell command processor (#1949)

Co-authored-by: Jacob Richman <jacob314@gmail.com>
Co-authored-by: Sandy Tao <sandytao520@icloud.com>
This commit is contained in:
BOYI 2025-07-22 06:26:40 +08:00 committed by GitHub
parent 4c3532d2b3
commit 12765eb775
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
7 changed files with 696 additions and 9 deletions

7
package-lock.json generated
View File

@ -3615,6 +3615,12 @@
"node": ">=8"
}
},
"node_modules/chardet": {
"version": "2.1.0",
"resolved": "https://registry.npmjs.org/chardet/-/chardet-2.1.0.tgz",
"integrity": "sha512-bNFETTG/pM5ryzQ9Ad0lJOTa6HWD/YsScAR3EnCPZRPlQh77JocYktSHOUHelyhm8IARL+o4c4F1bP5KVOjiRA==",
"license": "MIT"
},
"node_modules/check-error": {
"version": "2.1.1",
"resolved": "https://registry.npmjs.org/check-error/-/check-error-2.1.1.tgz",
@ -11813,6 +11819,7 @@
"@types/glob": "^8.1.0",
"@types/html-to-text": "^9.0.4",
"ajv": "^8.17.1",
"chardet": "^2.1.0",
"diff": "^7.0.0",
"dotenv": "^17.1.0",
"glob": "^10.4.5",

View File

@ -19,9 +19,11 @@ vi.mock('os', () => ({
default: {
platform: () => 'linux',
tmpdir: () => '/tmp',
homedir: () => '/home/user',
},
platform: () => 'linux',
tmpdir: () => '/tmp',
homedir: () => '/home/user',
}));
vi.mock('@google/gemini-cli-core');
vi.mock('../utils/textUtils.js', () => ({

View File

@ -5,14 +5,18 @@
*/
import { spawn } from 'child_process';
import { StringDecoder } from 'string_decoder';
import { TextDecoder } from 'util';
import {
HistoryItemWithoutId,
IndividualToolCallDisplay,
ToolCallStatus,
} from '../types.js';
import { useCallback } from 'react';
import { Config, GeminiClient } from '@google/gemini-cli-core';
import {
Config,
GeminiClient,
getCachedEncodingForBuffer,
} from '@google/gemini-cli-core';
import { type PartListUnion } from '@google/genai';
import { formatMemoryUsage } from '../utils/formatters.js';
import { isBinary } from '../utils/textUtils.js';
@ -71,8 +75,8 @@ function executeShellCommand(
});
// Use decoders to handle multi-byte characters safely (for streaming output).
const stdoutDecoder = new StringDecoder('utf8');
const stderrDecoder = new StringDecoder('utf8');
let stdoutDecoder: TextDecoder | null = null;
let stderrDecoder: TextDecoder | null = null;
let stdout = '';
let stderr = '';
@ -85,6 +89,12 @@ function executeShellCommand(
let sniffedBytes = 0;
const handleOutput = (data: Buffer, stream: 'stdout' | 'stderr') => {
if (!stdoutDecoder || !stderrDecoder) {
const encoding = getCachedEncodingForBuffer(data);
stdoutDecoder = new TextDecoder(encoding);
stderrDecoder = new TextDecoder(encoding);
}
outputChunks.push(data);
if (streamToUi && sniffedBytes < MAX_SNIFF_SIZE) {
@ -101,8 +111,8 @@ function executeShellCommand(
const decodedChunk =
stream === 'stdout'
? stdoutDecoder.write(data)
: stderrDecoder.write(data);
? stdoutDecoder.decode(data, { stream: true })
: stderrDecoder.decode(data, { stream: true });
if (stream === 'stdout') {
stdout += stripAnsi(decodedChunk);
} else {
@ -160,8 +170,12 @@ function executeShellCommand(
abortSignal.removeEventListener('abort', abortHandler);
// Handle any final bytes lingering in the decoders
stdout += stdoutDecoder.end();
stderr += stderrDecoder.end();
if (stdoutDecoder) {
stdout += stdoutDecoder.decode();
}
if (stderrDecoder) {
stderr += stderrDecoder.decode();
}
const finalBuffer = Buffer.concat(outputChunks);

View File

@ -44,7 +44,8 @@
"simple-git": "^3.28.0",
"strip-ansi": "^7.1.0",
"undici": "^7.10.0",
"ws": "^8.18.0"
"ws": "^8.18.0",
"chardet": "^2.1.0"
},
"devDependencies": {
"@types/diff": "^7.0.2",

View File

@ -35,6 +35,7 @@ export * from './utils/editor.js';
export * from './utils/quotaErrorDetection.js';
export * from './utils/fileUtils.js';
export * from './utils/retry.js';
export * from './utils/systemEncoding.js';
// Export services
export * from './services/fileDiscoveryService.js';

View File

@ -0,0 +1,496 @@
/**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import { vi, describe, it, expect, beforeEach, afterEach } from 'vitest';
import { execSync } from 'child_process';
import * as os from 'os';
import { detect as chardetDetect } from 'chardet';
// Mock dependencies
vi.mock('child_process');
vi.mock('os');
vi.mock('chardet');
// Import the functions we want to test after refactoring
import {
getCachedEncodingForBuffer,
getSystemEncoding,
windowsCodePageToEncoding,
detectEncodingFromBuffer,
resetEncodingCache,
} from './systemEncoding.js';
describe('Shell Command Processor - Encoding Functions', () => {
let consoleWarnSpy: ReturnType<typeof vi.spyOn>;
let mockedExecSync: ReturnType<typeof vi.mocked<typeof execSync>>;
let mockedOsPlatform: ReturnType<typeof vi.mocked<() => string>>;
let mockedChardetDetect: ReturnType<typeof vi.mocked<typeof chardetDetect>>;
beforeEach(() => {
consoleWarnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
mockedExecSync = vi.mocked(execSync);
mockedOsPlatform = vi.mocked(os.platform);
mockedChardetDetect = vi.mocked(chardetDetect);
// Reset the encoding cache before each test
resetEncodingCache();
// Clear environment variables that might affect tests
delete process.env.LC_ALL;
delete process.env.LC_CTYPE;
delete process.env.LANG;
});
afterEach(() => {
vi.restoreAllMocks();
resetEncodingCache();
});
describe('windowsCodePageToEncoding', () => {
it('should map common Windows code pages correctly', () => {
expect(windowsCodePageToEncoding(437)).toBe('cp437');
expect(windowsCodePageToEncoding(850)).toBe('cp850');
expect(windowsCodePageToEncoding(65001)).toBe('utf-8');
expect(windowsCodePageToEncoding(1252)).toBe('windows-1252');
expect(windowsCodePageToEncoding(932)).toBe('shift_jis');
expect(windowsCodePageToEncoding(936)).toBe('gb2312');
expect(windowsCodePageToEncoding(949)).toBe('euc-kr');
expect(windowsCodePageToEncoding(950)).toBe('big5');
expect(windowsCodePageToEncoding(1200)).toBe('utf-16le');
expect(windowsCodePageToEncoding(1201)).toBe('utf-16be');
});
it('should return null for unmapped code pages and warn', () => {
expect(windowsCodePageToEncoding(99999)).toBe(null);
expect(consoleWarnSpy).toHaveBeenCalledWith(
'Unable to determine encoding for windows code page 99999.',
);
});
it('should handle all Windows-specific code pages', () => {
expect(windowsCodePageToEncoding(874)).toBe('windows-874');
expect(windowsCodePageToEncoding(1250)).toBe('windows-1250');
expect(windowsCodePageToEncoding(1251)).toBe('windows-1251');
expect(windowsCodePageToEncoding(1253)).toBe('windows-1253');
expect(windowsCodePageToEncoding(1254)).toBe('windows-1254');
expect(windowsCodePageToEncoding(1255)).toBe('windows-1255');
expect(windowsCodePageToEncoding(1256)).toBe('windows-1256');
expect(windowsCodePageToEncoding(1257)).toBe('windows-1257');
expect(windowsCodePageToEncoding(1258)).toBe('windows-1258');
});
});
describe('detectEncodingFromBuffer', () => {
it('should detect encoding using chardet successfully', () => {
const buffer = Buffer.from('test content', 'utf8');
mockedChardetDetect.mockReturnValue('UTF-8');
const result = detectEncodingFromBuffer(buffer);
expect(result).toBe('utf-8');
expect(mockedChardetDetect).toHaveBeenCalledWith(buffer);
});
it('should handle chardet returning mixed case encoding', () => {
const buffer = Buffer.from('test content', 'utf8');
mockedChardetDetect.mockReturnValue('ISO-8859-1');
const result = detectEncodingFromBuffer(buffer);
expect(result).toBe('iso-8859-1');
});
it('should return null when chardet fails', () => {
const buffer = Buffer.from('test content', 'utf8');
mockedChardetDetect.mockImplementation(() => {
throw new Error('Detection failed');
});
const result = detectEncodingFromBuffer(buffer);
expect(result).toBe(null);
expect(consoleWarnSpy).toHaveBeenCalledWith(
'Failed to detect encoding with chardet:',
expect.any(Error),
);
});
it('should return null when chardet returns null', () => {
const buffer = Buffer.from('test content', 'utf8');
mockedChardetDetect.mockReturnValue(null);
const result = detectEncodingFromBuffer(buffer);
expect(result).toBe(null);
});
it('should return null when chardet returns non-string', () => {
const buffer = Buffer.from('test content', 'utf8');
mockedChardetDetect.mockReturnValue([
'utf-8',
'iso-8859-1',
] as unknown as string);
const result = detectEncodingFromBuffer(buffer);
expect(result).toBe(null);
});
});
describe('getSystemEncoding - Windows', () => {
beforeEach(() => {
mockedOsPlatform.mockReturnValue('win32');
});
it('should parse Windows chcp output correctly', () => {
mockedExecSync.mockReturnValue('Active code page: 65001');
const result = getSystemEncoding();
expect(result).toBe('utf-8');
expect(mockedExecSync).toHaveBeenCalledWith('chcp', { encoding: 'utf8' });
});
it('should handle different chcp output formats', () => {
mockedExecSync.mockReturnValue('Current code page: 1252');
const result = getSystemEncoding();
expect(result).toBe('windows-1252');
});
it('should handle chcp output with extra whitespace', () => {
mockedExecSync.mockReturnValue('Active code page: 437 ');
const result = getSystemEncoding();
expect(result).toBe('cp437');
});
it('should return null when chcp command fails', () => {
mockedExecSync.mockImplementation(() => {
throw new Error('Command failed');
});
const result = getSystemEncoding();
expect(result).toBe(null);
expect(consoleWarnSpy).toHaveBeenCalledWith(
expect.stringContaining(
"Failed to get Windows code page using 'chcp' command",
),
);
});
it('should return null when chcp output cannot be parsed', () => {
mockedExecSync.mockReturnValue('Unexpected output format');
const result = getSystemEncoding();
expect(result).toBe(null);
expect(consoleWarnSpy).toHaveBeenCalledWith(
expect.stringContaining(
"Failed to get Windows code page using 'chcp' command",
),
);
});
it('should return null when code page is not a number', () => {
mockedExecSync.mockReturnValue('Active code page: abc');
const result = getSystemEncoding();
expect(result).toBe(null);
expect(consoleWarnSpy).toHaveBeenCalledWith(
expect.stringContaining(
"Failed to get Windows code page using 'chcp' command",
),
);
});
it('should return null when code page maps to null', () => {
mockedExecSync.mockReturnValue('Active code page: 99999');
const result = getSystemEncoding();
expect(result).toBe(null);
// Should warn about unknown code page from windowsCodePageToEncoding
expect(consoleWarnSpy).toHaveBeenCalledWith(
'Unable to determine encoding for windows code page 99999.',
);
});
});
describe('getSystemEncoding - Unix-like', () => {
beforeEach(() => {
mockedOsPlatform.mockReturnValue('linux');
});
it('should parse locale from LC_ALL environment variable', () => {
process.env.LC_ALL = 'en_US.UTF-8';
const result = getSystemEncoding();
expect(result).toBe('utf-8');
});
it('should parse locale from LC_CTYPE when LC_ALL is not set', () => {
process.env.LC_CTYPE = 'fr_FR.ISO-8859-1';
const result = getSystemEncoding();
expect(result).toBe('iso-8859-1');
});
it('should parse locale from LANG when LC_ALL and LC_CTYPE are not set', () => {
process.env.LANG = 'de_DE.UTF-8';
const result = getSystemEncoding();
expect(result).toBe('utf-8');
});
it('should handle locale charmap command when environment variables are empty', () => {
mockedExecSync.mockReturnValue('UTF-8\n');
const result = getSystemEncoding();
expect(result).toBe('utf-8');
expect(mockedExecSync).toHaveBeenCalledWith('locale charmap', {
encoding: 'utf8',
});
});
it('should handle locale charmap with mixed case', () => {
mockedExecSync.mockReturnValue('ISO-8859-1\n');
const result = getSystemEncoding();
expect(result).toBe('iso-8859-1');
});
it('should return null when locale charmap fails', () => {
mockedExecSync.mockImplementation(() => {
throw new Error('Command failed');
});
const result = getSystemEncoding();
expect(result).toBe(null);
expect(consoleWarnSpy).toHaveBeenCalledWith(
'Failed to get locale charmap.',
);
});
it('should handle locale without encoding (no dot)', () => {
process.env.LANG = 'C';
const result = getSystemEncoding();
expect(result).toBe('c');
});
it('should handle empty locale environment variables', () => {
process.env.LC_ALL = '';
process.env.LC_CTYPE = '';
process.env.LANG = '';
mockedExecSync.mockReturnValue('UTF-8');
const result = getSystemEncoding();
expect(result).toBe('utf-8');
});
it('should return locale as-is when locale format has no dot', () => {
process.env.LANG = 'invalid_format';
const result = getSystemEncoding();
expect(result).toBe('invalid_format');
});
it('should prioritize LC_ALL over other environment variables', () => {
process.env.LC_ALL = 'en_US.UTF-8';
process.env.LC_CTYPE = 'fr_FR.ISO-8859-1';
process.env.LANG = 'de_DE.CP1252';
const result = getSystemEncoding();
expect(result).toBe('utf-8');
});
it('should prioritize LC_CTYPE over LANG', () => {
process.env.LC_CTYPE = 'fr_FR.ISO-8859-1';
process.env.LANG = 'de_DE.CP1252';
const result = getSystemEncoding();
expect(result).toBe('iso-8859-1');
});
});
describe('getEncodingForBuffer', () => {
beforeEach(() => {
mockedOsPlatform.mockReturnValue('linux');
});
it('should use cached system encoding on subsequent calls', () => {
process.env.LANG = 'en_US.UTF-8';
const buffer = Buffer.from('test');
// First call
const result1 = getCachedEncodingForBuffer(buffer);
expect(result1).toBe('utf-8');
// Change environment (should not affect cached result)
process.env.LANG = 'fr_FR.ISO-8859-1';
// Second call should use cached value
const result2 = getCachedEncodingForBuffer(buffer);
expect(result2).toBe('utf-8');
});
it('should fall back to buffer detection when system encoding fails', () => {
// No environment variables set
mockedExecSync.mockImplementation(() => {
throw new Error('locale command failed');
});
const buffer = Buffer.from('test');
mockedChardetDetect.mockReturnValue('ISO-8859-1');
const result = getCachedEncodingForBuffer(buffer);
expect(result).toBe('iso-8859-1');
expect(mockedChardetDetect).toHaveBeenCalledWith(buffer);
});
it('should fall back to utf-8 when both system and buffer detection fail', () => {
// System encoding fails
mockedExecSync.mockImplementation(() => {
throw new Error('locale command failed');
});
// Buffer detection fails
mockedChardetDetect.mockImplementation(() => {
throw new Error('chardet failed');
});
const buffer = Buffer.from('test');
const result = getCachedEncodingForBuffer(buffer);
expect(result).toBe('utf-8');
});
it('should not cache buffer detection results', () => {
// System encoding fails initially
mockedExecSync.mockImplementation(() => {
throw new Error('locale command failed');
});
const buffer1 = Buffer.from('test1');
const buffer2 = Buffer.from('test2');
mockedChardetDetect
.mockReturnValueOnce('ISO-8859-1')
.mockReturnValueOnce('UTF-16');
const result1 = getCachedEncodingForBuffer(buffer1);
const result2 = getCachedEncodingForBuffer(buffer2);
expect(result1).toBe('iso-8859-1');
expect(result2).toBe('utf-16');
expect(mockedChardetDetect).toHaveBeenCalledTimes(2);
});
it('should handle Windows system encoding', () => {
mockedOsPlatform.mockReturnValue('win32');
mockedExecSync.mockReturnValue('Active code page: 1252');
const buffer = Buffer.from('test');
const result = getCachedEncodingForBuffer(buffer);
expect(result).toBe('windows-1252');
});
it('should cache null system encoding result', () => {
// Reset the cache specifically for this test
resetEncodingCache();
// Ensure we're on Unix-like for this test
mockedOsPlatform.mockReturnValue('linux');
// System encoding detection returns null
mockedExecSync.mockImplementation(() => {
throw new Error('locale command failed');
});
const buffer1 = Buffer.from('test1');
const buffer2 = Buffer.from('test2');
mockedChardetDetect
.mockReturnValueOnce('ISO-8859-1')
.mockReturnValueOnce('UTF-16');
// Clear any previous calls from beforeEach setup or previous tests
mockedExecSync.mockClear();
const result1 = getCachedEncodingForBuffer(buffer1);
const result2 = getCachedEncodingForBuffer(buffer2);
// Should call execSync only once due to caching (null result is cached)
expect(mockedExecSync).toHaveBeenCalledTimes(1);
expect(result1).toBe('iso-8859-1');
expect(result2).toBe('utf-16');
// Call a third time to verify cache is still used
const buffer3 = Buffer.from('test3');
mockedChardetDetect.mockReturnValueOnce('UTF-32');
const result3 = getCachedEncodingForBuffer(buffer3);
// Still should be only one call to execSync
expect(mockedExecSync).toHaveBeenCalledTimes(1);
expect(result3).toBe('utf-32');
});
});
describe('Cross-platform behavior', () => {
it('should work correctly on macOS', () => {
mockedOsPlatform.mockReturnValue('darwin');
process.env.LANG = 'en_US.UTF-8';
const result = getSystemEncoding();
expect(result).toBe('utf-8');
});
it('should work correctly on other Unix-like systems', () => {
mockedOsPlatform.mockReturnValue('freebsd');
process.env.LANG = 'en_US.UTF-8';
const result = getSystemEncoding();
expect(result).toBe('utf-8');
});
it('should handle unknown platforms as Unix-like', () => {
mockedOsPlatform.mockReturnValue('unknown' as NodeJS.Platform);
process.env.LANG = 'en_US.UTF-8';
const result = getSystemEncoding();
expect(result).toBe('utf-8');
});
});
describe('Edge cases and error handling', () => {
it('should handle empty buffer gracefully', () => {
mockedOsPlatform.mockReturnValue('linux');
process.env.LANG = 'en_US.UTF-8';
const buffer = Buffer.alloc(0);
const result = getCachedEncodingForBuffer(buffer);
expect(result).toBe('utf-8');
});
it('should handle very large buffers', () => {
mockedOsPlatform.mockReturnValue('linux');
process.env.LANG = 'en_US.UTF-8';
const buffer = Buffer.alloc(1024 * 1024, 'a');
const result = getCachedEncodingForBuffer(buffer);
expect(result).toBe('utf-8');
});
it('should handle Unicode content', () => {
mockedOsPlatform.mockReturnValue('linux');
const unicodeText = '你好世界 🌍 ñoño';
// System encoding fails
mockedExecSync.mockImplementation(() => {
throw new Error('locale command failed');
});
mockedChardetDetect.mockReturnValue('UTF-8');
const buffer = Buffer.from(unicodeText, 'utf8');
const result = getCachedEncodingForBuffer(buffer);
expect(result).toBe('utf-8');
});
});
});

View File

@ -0,0 +1,166 @@
/**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import { execSync } from 'child_process';
import os from 'os';
import { detect as chardetDetect } from 'chardet';
// Cache for system encoding to avoid repeated detection
// Use undefined to indicate "not yet checked" vs null meaning "checked but failed"
let cachedSystemEncoding: string | null | undefined = undefined;
/**
* Reset the encoding cache - useful for testing
*/
export function resetEncodingCache(): void {
cachedSystemEncoding = undefined;
}
/**
* Returns the system encoding, caching the result to avoid repeated system calls.
* If system encoding detection fails, falls back to detecting from the provided buffer.
* Note: Only the system encoding is cached - buffer-based detection runs for each buffer
* since different buffers may have different encodings.
* @param buffer A buffer to use for detecting encoding if system detection fails.
*/
export function getCachedEncodingForBuffer(buffer: Buffer): string {
// Cache system encoding detection since it's system-wide
if (cachedSystemEncoding === undefined) {
cachedSystemEncoding = getSystemEncoding();
}
// If we have a cached system encoding, use it
if (cachedSystemEncoding) {
return cachedSystemEncoding;
}
// Otherwise, detect from this specific buffer (don't cache this result)
return detectEncodingFromBuffer(buffer) || 'utf-8';
}
/**
* Detects the system encoding based on the platform.
* For Windows, it uses the 'chcp' command to get the current code page.
* For Unix-like systems, it checks environment variables like LC_ALL, LC_CTYPE, and LANG.
* If those are not set, it tries to run 'locale charmap' to get the encoding.
* If detection fails, it returns null.
* @returns The system encoding as a string, or null if detection fails.
*/
export function getSystemEncoding(): string | null {
// Windows
if (os.platform() === 'win32') {
try {
const output = execSync('chcp', { encoding: 'utf8' });
const match = output.match(/:\s*(\d+)/);
if (match) {
const codePage = parseInt(match[1], 10);
if (!isNaN(codePage)) {
return windowsCodePageToEncoding(codePage);
}
}
// Only warn if we can't parse the output format, not if windowsCodePageToEncoding fails
throw new Error(
`Unable to parse Windows code page from 'chcp' output "${output.trim()}". `,
);
} catch (error) {
console.warn(
`Failed to get Windows code page using 'chcp' command: ${error instanceof Error ? error.message : String(error)}. ` +
`Will attempt to detect encoding from command output instead.`,
);
}
return null;
}
// Unix-like
// Use environment variables LC_ALL, LC_CTYPE, and LANG to determine the
// system encoding. However, these environment variables might not always
// be set or accurate. Handle cases where none of these variables are set.
const env = process.env;
let locale = env.LC_ALL || env.LC_CTYPE || env.LANG || '';
// Fallback to querying the system directly when environment variables are missing
if (!locale) {
try {
locale = execSync('locale charmap', { encoding: 'utf8' })
.toString()
.trim();
} catch (_e) {
console.warn('Failed to get locale charmap.');
return null;
}
}
const match = locale.match(/\.(.+)/); // e.g., "en_US.UTF-8"
if (match && match[1]) {
return match[1].toLowerCase();
}
// Handle cases where locale charmap returns just the encoding name (e.g., "UTF-8")
if (locale && !locale.includes('.')) {
return locale.toLowerCase();
}
return null;
}
/**
* Converts a Windows code page number to a corresponding encoding name.
* @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.
*/
export function windowsCodePageToEncoding(cp: number): string | null {
// Most common mappings; extend as needed
const map: { [key: number]: string } = {
437: 'cp437',
850: 'cp850',
852: 'cp852',
866: 'cp866',
874: 'windows-874',
932: 'shift_jis',
936: 'gb2312',
949: 'euc-kr',
950: 'big5',
1200: 'utf-16le',
1201: 'utf-16be',
1250: 'windows-1250',
1251: 'windows-1251',
1252: 'windows-1252',
1253: 'windows-1253',
1254: 'windows-1254',
1255: 'windows-1255',
1256: 'windows-1256',
1257: 'windows-1257',
1258: 'windows-1258',
65001: 'utf-8',
};
if (map[cp]) {
return map[cp];
}
console.warn(`Unable to determine encoding for windows code page ${cp}.`);
return null; // Return null if no mapping found
}
/**
* Attempts to detect encoding from a buffer using chardet.
* This is useful when system encoding detection fails.
* Returns the detected encoding in lowercase, or null if detection fails.
* @param buffer The buffer to analyze for encoding.
* @return The detected encoding as a lowercase string, or null if detection fails.
*/
export function detectEncodingFromBuffer(buffer: Buffer): string | null {
try {
const detected = chardetDetect(buffer);
if (detected && typeof detected === 'string') {
return detected.toLowerCase();
}
} catch (error) {
console.warn('Failed to detect encoding with chardet:', error);
}
return null;
}