Professional internationalization management for VS Code

i18n CodeLens is a comprehensive translation management extension that streamlines localization workflows for JavaScript, TypeScript, and React projects. It provides intelligent detection of translation keys, visual indicators for missing translations, and powerful editing tools—all integrated directly into your development environment.

Architecture update: The standalone MCP server and shared i18n engine now live in the companion npm package i18n-codelens-mcp (GitHub). This repository stays focused on the VS Code extension experience and automatically wires that backend into VS Code.

The extension can be customized for different project structures through configurable regex patterns and glob settings, making it adaptable to various i18n frameworks and conventions.

• 🤖 MCP Integration & Automation: MCP integration with rich i18n tools; auto-registers via VS Code LM API and shares its engine with the standalone i18n-codelens-mcp package
• 🔍 Smart Translation Detection: Automatically detects translation keys in your code using configurable regex patterns
• 📋 Bulk Translation Editor: Professional WebView-based interface for editing multiple translation keys simultaneously
• 📝 Resource Edit Screen: WebView-based multiline add/edit screen for individual translation actions, with a setting to fall back to legacy single-line inputs
• 🎯 Interactive Hover Actions: Click-to-edit, add, or delete translations directly from hover popups
• 🌐 Multi-Language Support: Works with JavaScript, TypeScript, React (JSX/TSX) files
• 📊 Visual Indicators: Color-coded decorations showing translation status (missing, partial, complete)
• 🔄 Real-time Validation: Instant feedback on missing translations with CodeLens integration
• 🗂️ Resource Tree View: Organized view of all translation keys with quick navigation
• ⚡ Smart Suggestions: Auto-completion and closest-match positioning for new translations
• 🧱 Flat/Nested Awareness: Detects flat translation dictionaries and deeply nested JSON, preserving structure during edits
• 🧭 Insert Order Strategies: Control how new keys are placed in locale files — append to end, insert near the closest key (Levenshtein), or fully sort A→Z

Concise highlights only (see full details in the Change Log below):

• MCP architecture split
  • Standalone MCP server and shared i18n engine are now published from i18n-codelens-mcp
  • This extension remains focused on VS Code UX and auto-registers that shared backend
  • External MCP clients should use the npm package instead of this repository as the integration surface
• Expanded MCP capability surface
  • Shared backend now includes project info, search, namespace inspection, audit, unused key detection, and formatting tools
• New resource edit experience
  • Add/edit translation actions can open the new WebView-based multiline resource edit screen
  • experimental.multilineTranslationInput controls whether the new screen or legacy single-line inputs are used
• Shared behavior across editor and standalone flows
  • Config, resource structure handling, ordering rules, and file safety checks now come from the same package

The extension includes Model Context Protocol (MCP) integration for AI-powered automation.

VS Code LM API (Recommended)
The extension automatically registers with VS Code's Language Model API. Compatible clients like GitHub Copilot Agentic, Claude for VS Code, and other MCP-aware tools can invoke the tools without additional configuration.

Standalone MCP Package
External CLI and desktop clients should use the separate i18n-codelens-mcp package. That package contains the public npx -y i18n-codelens-mcp server, external client setup examples, and the full standalone MCP documentation.

Helpful links:

• npm: i18n-codelens-mcp
• GitHub: hepter/i18n-codelens-mcp

Note: The npm run mcp and npm run inspect scripts in this repository are kept for extension development and inspector testing.

Customize server behavior with these environment variables:

• I18N_GLOB — Pattern for resource files (defaults to **/locales/**/*.json)
• I18N_CODE_REGEX — Custom regex for detecting translation keys
• I18N_CODE_GLOB — Pattern for code files (defaults to **/*.{ts,tsx,js,jsx})
• I18N_IGNORE — Additional glob patterns to ignore (e.g., **/dist/**;**/.next/**); .gitignore is also respected
• I18N_STRUCTURE — Controls write structure (auto | flat | nested)
• I18N_INSERT_ORDER — Controls insert order (append | nearby | sort)

You can also override the workspace root via CLI args:

• --workspaceRoot <path> (or --workspace-root <path>, including --workspaceRoot=<path>)

Workspace root resolution order is: CLI arg → WORKSPACE_ROOT env → process.cwd() → server path fallback.

Note: Auto-registration requires VS Code 1.118.0 or newer. External MCP clients should use the standalone i18n-codelens-mcp package.

These tools integrate with AI workflows to automate translation validation, identify gaps, and streamline localization management.

External client setup examples for Claude Code, Gemini CLI, OpenAI Codex CLI, Claude Desktop, Cursor, Windsurf, and manual MCP config files are maintained in the standalone package documentation:

• npm: i18n-codelens-mcp
• GitHub: hepter/i18n-codelens-mcp

The extension intelligently handles both flat and nested translation file structures:

• Automatic detection: Identifies whether files use flat key-value maps or nested object hierarchies
• Internal flattening: Processes nested structures internally for search and CodeLens functionality
• Structure preservation: Maintains original formatting when writing updates to disk
• Flexibility: Edit deeply nested locale files without manual flattening, while keeping MCP automation fully functional

• Changed: Standalone MCP server and shared i18n engine are now distributed from the published i18n-codelens-mcp package.
• Changed: This extension remains the editor-facing layer and auto-registers that shared MCP backend via the VS Code LM API.
• Added: New WebView-based multiline resource edit screen for add/edit translation actions.
• Added: experimental.multilineTranslationInput setting to switch between the new resource edit screen and legacy single-line inputs.
• Added: README guidance now points external MCP clients to the npm package for setup, installation, and the expanded tool surface.
• Refactored: Shared config and resource utilities are sourced from the MCP package so editor and standalone behavior stay aligned.

• Fixed: Standalone MCP now prefers process.cwd() as the workspace root, improving multi-project usage in external MCP clients.
• Added: CLI override for workspace root via --workspaceRoot / --workspace-root (also supports --workspaceRoot=<path>).
• Fixed: Standalone MCP logging uses stderr-safe output to avoid stdio protocol interference.
• Fixed: Workspace scanning now skips symbolic links and suppresses traversal errors, preventing EPERM/broken-link scan failures.
• Improved: MCP file operations enforce workspace-bound writes/reads and reject symlink-based path escapes.

• Stabilized MCP registration (single supported constructor, no fallbacks, with new log channel for MCP Server)
• Non‑blocking logging with graceful console fallback
• Useful diagnostics: startup config + per‑tool success/error with durations

• Fixed: MCP duplicate tool registrations in GitHub Copilot Chat by pruning stale/invalid mcpServers entries and keeping only the current server path at activation.
• Improved: More robust MCP provider lifecycle (re-register/dispose) with safer error handling.
• Note: After upgrading, use “Developer: Reload Window”. If duplicates persist, remove old entries under github.copilotChat.mcpServers once in Settings (JSON).

• Added: resourceInsertOrderStrategy setting with configurable strategies (append, nearby, sort) so you decide how new translations are positioned; nearby uses closest-match heuristics by default.
• Added: I18N_INSERT_ORDER environment variable and MCP wiring to keep Copilot/Inspector automation aligned with the chosen insert strategy.
• Improved: Translation writes (flat or nested JSON) preserve original ordering unless explicit alphabetical sorting is requested, preventing unexpected churn in locale files.
• Improved: Shared ordering utilities reuse the same Levenshtein-based placement logic across extension actions and MCP tools for consistent behaviour.

• Added: Model Context Protocol stdio server with five automation tools and VS Code LM auto-registration
• Added: Automatic detection of nested translation files with safe flatten/unflatten helpers
• Added: overviewRulerMarkers setting for scroll bar indicators
• Improved: Resource sorting and .gitignore handling for stable results across features
• Improved: Manual MCP usage through the standalone i18n-codelens-mcp package and environment overrides
• Improved: Cleaner scroll bar with smart indicators - only problematic translations are highlighted
• Updated: Minimum VS Code version to ^1.96.0 to enable LM/MCP integration

• Enhanced: Logger system with structured log levels (debug, info, warn, error) and configurable logLevel setting
• Added: New codeFileRegex setting for customizable code file pattern matching (default: /\.(jsx?|tsx?)$/)
• Added: .gitignore integration for file filtering during workspace scanning
• Improved: Resource scanning performance with optimized regex handling and execution patterns
• Improved: Code file detection with proper filtering of ignored files and relative path handling
• Enhanced: Input dialogs with VS Code InputBox API, step progress indicators, and validation feedback
• Enhanced: Hover provider with improved layout, inline edit actions, and action links
• Enhanced: Error handling with proper categorization and user-friendly error messages
• Fixed: Type error in ResourceTreeViewProvider.ts related to range character access
• Fixed: Function closure issue in ActionResetAndReloadExtension.ts error handling
• Fixed: Code action provider regex matching to use appropriate code detection pattern
• Fixed: Resource line regex execution with proper global flag handling
• Updated: Dependencies - fastest-levenshtein to v1.0.16 and added ignore v7.0.5
• Updated: TypeScript configuration to ES2020 target with enhanced module resolution

• Major Feature: Added comprehensive bulk translation editing system with WebView interface
• Enhanced: Hover provider with interactive edit/add/delete action links
• Improved: JSON-safe file operations preventing trailing comma corruption
• Added: Source file tracking for bulk edit operations
• Enhanced: Error handling and logging throughout the extension
• Extended: Language support for React files (JSX/TSX)
• Fixed: WebView modal restrictions with custom confirmation dialogs
• Improved: Resource tree view performance and reliability

• Internal RegExp & Glob Pattern updated to support better matching

• Multiple resource key detection fixed at single line for Hover and Code Action Providers

• Logs forwarded to custom i18n CodeLens output channel
• Minor fixes

Performance tweaks & refactored with new features

• Resource Tree view added to Explorer with new configs
• Similar providers centralized
• All settings and reloading data moved to SettingUtils
• Resource delete action added for Code or Resource file
• Action & Configuration settings renamed properly
• Resource hover text fixed after save

• Fix: Missing glob validation added to show properly

• Definition Provider added so that language resource references can be found with 'go to definition' command or Ctrl+click
• Unused resources now show as half-transparent and give hover information on .json language resource files

• Initial release

Default detection regex:
(?<=\/\*\*\s*?@i18n\s*?\*\/\s*?["']|\W[tT]\(\s*["'])(?<key>[A-Za-z0-9 .-_]+?)(?=["])

This matches:

• t('key') or T('key') — Function call patterns
• /** @i18n */ 'key' — Comment annotation pattern

The extension automatically detects translation keys using these patterns:

// Function call patterns
t('welcome.message')           // lowercase
T('user.greeting')             // uppercase

// JSX/TSX usage
<Text>{t('button.submit')}</Text>

// Annotation pattern
/** @i18n */ 'settings.title'

Add Missing Translations

1. Hover over any translation key with missing translations
2. Click "Add Translations" in the hover popup
3. Enter translations in the WebView-based multiline resource edit screen when experimental.multilineTranslationInput is enabled
4. Files are saved automatically (if resourceAutoSave is enabled)

Edit Existing Translations

1. Hover over a translation key
2. Click "Edit Translations"
3. Modify values in the WebView-based multiline resource edit screen when experimental.multilineTranslationInput is enabled
4. Changes are applied instantly

Delete Translations

1. Hover over a translation key
2. Click "Delete Translations"
3. Confirm removal
4. Key is removed from all locale files

For efficient multi-key editing:

1. Open a file containing multiple translation keys
2. Hover over any key and click "📋 Bulk Edit (X keys)"
3. The visual editor opens with all keys from the current file
4. Edit, add, or delete multiple translations simultaneously
5. Click Save to apply all changes at once

Go to Definition
Ctrl+Click (or Cmd+Click) on any translation key to jump to its definition in locale files.

Resource Tree View
View all translations used in the active file organized by key, with visual indicators for:

• ✅ Complete translations (all languages present)
• ⚠️ Partial translations (some languages missing)
• ❌ Missing translations (key not found)

Issues and feature requests are welcome! Please check the GitHub repository for more information.

This project is licensed under the MIT License.