[amondnet]

Summary

Adds a global --locale <ko|en> flag for the output language and starts retiring --lang ko|en. --lang is reserved for a future programming-language selection, so its old meaning must not keep working silently. Previously a non-strict parseArgs ignored unknown values and fell back to $LANG.

• --locale <ko|en> is a global flag (packages/cli/src/index.ts, resolveLocaleFlags in src/i18n.ts). check accepts it too (src/check/run-check.ts).
• --lang ko|en still sets the locale but prints a deprecation warning that points at --locale, for one minor release. --locale wins when both are given.
• Any other --lang value, --lang without a value, or an unknown --locale value exits 1 with an error.
• Help text (both locales), packages/cli/README.md, README.ko.md, and apps/docs cli.mdx (en/ko) use --locale and describe the transition.

Scope and notes for reviewers

• The error does not list accepted languages yet (the feat(cli): detect languages, run without package.json, and split rules into rules/<lang>.md #65 AC wording), because programming-language selection is not implemented. Add the list when detection lands.
• Exit code 1 matches the existing unknown-command error.
• Removing the --lang ko|en fallback after one minor release is not tracked yet.
• Language detection and the no-package.json mode from feat(cli): detect languages, run without package.json, and split rules into rules/<lang>.md #65 remain, hence Refs rather than a closing keyword.

Verification

• bun test in packages/cli: 261 pass / 1 skip / 0 fail. New: 5 unit tests for resolveLocaleFlags (test/i18n.test.ts) and 3 subprocess tests (test/index.test.ts).
• tsc --noEmit and eslint clean; docs astro build and lint:docs clean (22 files).
• Manual runs: --lang ko|en|foo, bare --lang, --locale ko|fr, --locale en --lang ko, check --locale ko.

Related issue

Refs #65

Checklist

• PR title follows Conventional Commits
• Packages build (bun run build)
• Lint/format pass (bun run lint)
• Documentation updated if behavior changed
• No breaking change, or a BREAKING CHANGE: note is included

---

Summary by cubic

Adds a global --locale <ko|en> flag to select the CLI output language and deprecates --lang ko|en. --lang is reserved for future programming-language selection, so unknown values that were previously ignored now fail instead of silently falling back to $LANG. The migration path is documented in both locales' READMEs and docs.

Migration

• --lang ko|en still sets the locale for one minor release and prints a deprecation warning pointing at --locale.
• --locale wins when both flags are given; --lang then prints an "ignored" warning telling the user to remove it, so it is not mistaken for the migration target.
• Any other --lang value, a bare --lang, or an unknown --locale value exits 1.

^{Written for commit 7fd6040. Summary will update on new commits.}

Demo

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 31 complexity · 2 duplication

Metric	Results
Complexity	31
Duplication	2

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[gemini-code-assist]

Code Review

This pull request replaces the --lang flag with --locale for setting the CLI locale, while maintaining backward compatibility for --lang with a deprecation warning. It introduces a robust resolveLocaleFlags utility to handle locale configuration, adds validation for locale values, and updates documentation and tests accordingly. I have no feedback to provide.

[cubic-dev-ai]

All reported issues were addressed across 9 files

<sub>Reply with feedback, questions, or to request a fix.

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[greptile-apps]

Confidence Score: 5/5

[Medium impact] The changes appear safe to merge.

Summary

Adds --locale and keeps --lang ko|en temporarily, with a warning.

• CLI users choose the message language with --locale.

_{Reviews (2) · Last reviewed commit: "chore(cli): apply AI code review suggest..." · Reviewed by Greptile}

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View logs

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud