Add i18n / localization support for CLI interface language

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

Currently, all CLI interface text in Claude Code (prompts, help text, status messages, startup banners, etc.) is
hardcoded in English. It would be great to support localization so that non-English-speaking developers can use Claude
Code with a more familiar interface.

Proposed Solution

• Add a configuration option (e.g., language or locale in settings) to set the CLI display language.
• Externalize all user-facing strings into locale files.
• Start with a few high-demand languages (e.g., Chinese, Japanese, Spanish, French) and allow community contributions

for others.

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

Example:

# In settings or .claude.json
{
"locale": "zh-CN"
}

Use case:

Many developers worldwide use Claude Code daily but are not native English speakers. While they can communicate with
Claude in their own language, the surrounding CLI chrome — help text, prompts, feature descriptions, error messages —
remains in English. Localized interface text would lower the barrier to entry and improve the overall experience.

Additional Context

• This only applies to the CLI's own UI strings, not to Claude's conversational responses (which already adapt to the

user's language).

• A simple key-value locale file approach would make community translations easy to contribute.