[FEATURE] UI Localization / Language Support

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Summary

Claude Code UI is only available in English, regardless of the language configured in VS Code or the language used when communicating with Claude.

Problem

When VS Code is configured to use a non-English language (e.g., Spanish via the Spanish Language Pack), Claude Code still displays all UI elements in English, including:

• Confirmation dialogs ("Make this edit?")
• Action buttons ("Yes, allow all edits this session", "No")
• System messages and prompts
• Input placeholders ("Tell Claude what to do instead")

Additionally, even when the user writes prompts in Spanish, Claude Code tends to respond in English.

Expected Behavior

Claude Code should either:

1. Detect and respect the display language configured in VS Code, or
2. Provide a language setting within Claude Code itself, or
3. Consistently respond in the same language the user writes in

Steps to Reproduce

1. Install VS Code with the Spanish Language Pack
2. Set VS Code display language to Spanish (es)
3. Open Claude Code
4. Observe that all UI elements remain in English
5. Write a prompt in Spanish → response comes back in English

Environment

• VS Code with Spanish Language Pack installed
• Claude Code latest version

Additional Context

Localization support would greatly improve the experience for non-English speaking developers. Many developers worldwide use VS Code in their native language and would expect extensions to respect that setting.

Thank you for considering this improvement!

Proposed Solution

<img width="1359" height="645" alt="Image" src="https://github.com/user-attachments/assets/398b83fb-ec9b-45bd-b6cb-c811eaafa11e" />

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_