Configuring wpf-dev-pack Language

This skill writes (or updates) a per-project preference file that tells the wpf-dev-pack plugin which language to respond in. A SessionStart hook (hooks/LanguagePreferenceLoader.cs) reads the file on every new conversation and emits a directive into the system context, so the preference takes effect automatically.

When to use

• The default language of a response does not match what the user wants

(typical case: an English-speaking contributor in a project where wpf-dev-pack was originally tuned for Korean responses, or vice versa).

• The user wants to switch language mid-project.

When NOT to use

• The user only wants a one-off language switch for the next response —

just have them phrase the next message in the target language. Do not write a file for a one-shot.

• The wpf-dev-pack plugin is not installed in the current project — the

SessionStart hook will not run without the plugin.

Workflow

Copy this checklist and track progress:

Configure Progress:
- [ ] Step 1: Detect current state of .claude/wpf-dev-pack.local.md
- [ ] Step 2: Resolve target language (argument or AskUserQuestion)
- [ ] Step 3: Write or update .claude/wpf-dev-pack.local.md
- [ ] Step 4: Confirm and explain when the change takes effect

Step 1 — Detect current state

Check whether .claude/wpf-dev-pack.local.md exists in the current project root. If it does, read its YAML frontmatter and find any existing language: value so the user can see what they are replacing.

If the file does not exist, that is fine — Step 3 will create it.

Step 2 — Resolve target language

If $0 is provided, treat it as a BCP-47 language code (the IETF standard built on ISO 639 language codes):

The table above is illustrative, not exhaustive. Claude understands any valid BCP-47 / ISO 639-1 code (Claude Code does not maintain a closed allowlist). Authoritative references for code samples:

• BCP-47 specification (the IETF standard):

<https://www.rfc-editor.org/info/bcp47>

• IANA Language Subtag Registry (the canonical list of subtags):

<https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry>

• ISO 639-1 two-letter codes (quick reference):

<https://en.wikipedia.org/wiki/List_of_ISO_639_language_codes>

• W3C i18n introduction to BCP-47 (gentler reading):

<https://www.w3.org/International/articles/language-tags/>

Accept the value if it is a non-empty short token (letters, digits, hyphen). Reject and ask for clarification otherwise.

If $0 is missing, use AskUserQuestion with up to 4 options (typically Korean / English / Japanese / Chinese) plus an Other escape for free-form input. Surface the currently configured value from Step 1 so the user can see what they are replacing.

Step 3 — Write or update the file

If the file does not exist, create .claude/wpf-dev-pack.local.md with this minimal structure:

---
language: <code>
---

# wpf-dev-pack — Per-Project Local Settings

This file stores personal, per-project preferences for the wpf-dev-pack
plugin. It is read by the LanguagePreferenceLoader SessionStart hook on
every new conversation in this project.

This file is personal and should not be committed. The repo's
.gitignore covers `.claude/*.local.md`.

If the file already exists, only modify the language: field in its YAML frontmatter — preserve all other settings and the body verbatim. If the frontmatter is missing entirely, prepend one with just the language: field; do not touch the existing body.

Step 4 — Confirm

Tell the user:

1. Which file was written and which language: value it now contains.
2. The change does not affect the current conversation. The

SessionStart hook runs only at the start of a new session, so the user needs to begin a new conversation for the directive to be injected into the system context.

1. To revert to the default behavior, delete the file or remove its

language: field — the hook will then emit nothing and the plugin's default language behavior applies.

Notes

• The SessionStart hook adds a recommendation to the system context;

it does not hard-switch the model. Claude follows the recommendation by default, and the user can still override at any time ("respond in English please" / "한글로 답해줘").

• This skill is intentionally NOT auto-triggered. Changing the

conversation language is a meaningful side effect, so it must be invoked explicitly.

• The mechanism is wpf-dev-pack scoped. Other plugins or workflows in

the same project are unaffected.