feat: make check-in language configurable via HOYOLAB_LANG variable

The check-in request hardcoded `lang=en-us`, so the reward messages HoYoLAB
shows in game and in the check-in history were always English. Read the locale
from an optional `HOYOLAB_LANG` repository variable instead, defaulting to
`en-us`.

The name is prefixed rather than a plain `LANGUAGE` to avoid colliding with the
GNU gettext variable of that name when running index.js locally.

`||` is used rather than `??` because an unset repository variable is injected
as an empty string by Actions, which `??` would pass through as an empty `lang`.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/login.yml

@@ -30,6 +30,7 @@ jobs:
           DISCORD_USER: ${{ secrets.DISCORD_USER }}
           TELEGRAM_TOKEN: ${{ secrets.TELEGRAM_TOKEN }}
           TELEGRAM_CHAT_ID: ${{ secrets.TELEGRAM_CHAT_ID }}
+          HOYOLAB_LANG: ${{ vars.HOYOLAB_LANG }}
   workflow-keepalive:
     if: github.event_name == 'schedule'
     runs-on: ubuntu-latest

README.md

@@ -11,6 +11,7 @@ Repository version:
 - [Getting your cookie](#getting-your-cookie)
 - [Usage](#usage)
 - [Multiple Accounts](#multiple-accounts)
+- [Language](#language)
 - [Discord Webhook](#discord-webhook)
 - [Telegram](#telegram)
 - [FAQ](#faq)
@@ -119,6 +120,20 @@ You have to check in manually first to get your cookie, follow these steps (clic
   <img src="https://github.com/user-attachments/assets/4a56f4e1-8fb4-4137-acc6-ac30cade78f1" />
 </details>
 
+## Language
+
+Check in requests are made in English (`en-us`) by default. The language decides how
+HoYoLAB localizes the check in, so the reward messages you see in game and in the
+check in history follow it.
+
+To change it, create a new repository *variable* (Settings > Secrets and variables >
+Actions > Variables) named `HOYOLAB_LANG` with one of the values HoYoLAB supports:
+
+`zh-cn`, `zh-tw`, `de-de`, `en-us`, `es-es`, `fr-fr`, `id-id`, `it-it`, `ja-jp`,
+`ko-kr`, `pt-pt`, `ru-ru`, `th-th`, `tr-tr`, `vi-vn`
+
+Leaving the variable unset keeps the current `en-us` behaviour.
+
 ## Discord Webhook
 
 You may use Discord webhook to send notifications to your channel!

index.js

@@ -9,6 +9,11 @@ const discordWebhook = process.env.DISCORD_WEBHOOK
 const discordUser = process.env.DISCORD_USER
 const telegramToken = process.env.TELEGRAM_TOKEN
 const telegramChat = process.env.TELEGRAM_CHAT_ID
+// Locale sent to the check-in API, which decides the language of the reward
+// messages shown in-game and in the HoYoLAB check-in history.
+// `||` (not `??`) is intentional: an unset repository variable is injected as an
+// empty string by Actions, and an empty `lang` would be sent to the API.
+const language = process.env.HOYOLAB_LANG?.trim() || 'en-us'
 const msgDelimiter = ':'
 const icon = { info: '✅', error: '❌' }
 const messages = []
@@ -52,10 +57,10 @@ async function run(cookie, games) {
     const url = new URL(endpoint)
     const actId = url.searchParams.get('act_id')
 
-    url.searchParams.set('lang', 'en-us')
+    url.searchParams.set('lang', language)
 
     const body = JSON.stringify({
-      lang: 'en-us',
+      lang: language,
       act_id: actId
     })