Pull Request: Add i18n Infrastructure and Chinese (zh-CN) Localization

[smryyyyy]

Pull Request: Add i18n Infrastructure and Chinese (zh-CN) Localization

English | 中文

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Summary

This PR adds a lightweight internationalization (i18n) system and complete Simplified Chinese (zh-CN) translation to Pi for Excel.

Motivation: Pi for Excel has a growing user base in China. Previously all UI text was hardcoded in English, making it inaccessible to non-English speakers. This PR introduces a translation framework with zero third-party dependencies and provides a complete Chinese localization out of the box.

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Architecture

Translation System (src/language/)

A minimal, zero-dependency translation function that avoids adding any bundle overhead:

src/language/
├── index.ts           ← t() + initLanguage() + getLanguage()
└── locales/
    ├── en.json        ← English (source of truth, ~900 keys)
    └── zh-CN.json     ← Chinese translations (~900 keys)

Design decisions:

• No i18n library — keeps bundle size zero for Office WebView
• English as fallback — untranslated keys silently display the English string
• t("key", {vars}) — variable interpolation via {placeholder} syntax
• Language stored in SettingsStore — persisted across sessions
• Page reload on switch — simple, no runtime reactivity needed

API

import { t, initLanguage, getLanguage } from "../language/index.js";

// Basic usage
element.textContent = t("welcome.subtitle");

// Variable interpolation  (JSON: "{label} connected")
element.textContent = t("welcome.connected", { label: "DeepSeek" });

// Initialize at startup
initLanguage("zh-CN");

// Get current language
const lang = getLanguage(); // "en" | "zh-CN"

Language Switching

Two entry points for switching language:

1. Welcome screen — Language toggle (English / 中文) at top-right corner
2. Settings → Advanced → Language — Dropdown selector

Both save the preference to settings.language and reload the page.

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Changes by Category

Core Infrastructure (4 new files)

• src/language/index.ts — Translation function
• src/language/locales/en.json — English strings
• src/language/locales/zh-CN.json — Chinese strings
• cn_README.md — Chinese documentation

Modified Files (74 files)

Area	Files	Description
UI Components	15	Sidebar, input, working indicator, whimsical messages, dialogs, loading, toast, disclosure bar, proxy banner, bridge/web-search cards, message renderers, file dialogs
Taskpane	8	Welcome/login, status bar, session title, queue display, bootstrap, init, status context, status popovers
Commands	13	Model, settings, session, export, help, files, skills, addons, tools, debug, experimental, clipboard
Dialogs & Overlays	12	Settings, rules, shortcuts, resume, recovery, experimental, extensions hub (overlay + connections + plugins + skills), custom gateway
Backend	6	Execution mode, runtime manager, permissions, flags, thinking duration, relative date
Files	3	Backend, workspace, file dialog status
HTML	5	taskpane.html, ui-gallery.html, oauth-callback.html, index.html, architecture/index.html
Tools	2	Tool renderers, get-workbook-overview
Other	2	Workbook context, README.md

Key Fixes

1. Module-level t() timing bug — Several files had t() calls in module-level const declarations that executed before initLanguage() was called. Fixed by converting to lazy getter functions:

   • src/experiments/flags.ts — EXPERIMENTAL_FEATURES → getFeatures()
   • src/commands/builtins/settings-overlay.ts — SETTINGS_TABS → getSettingsTabs()
   • src/commands/builtins/shortcuts-overlay.ts — SHORTCUT_GROUPS → getShortcutGroups()
   • src/ui/confirm-dialog.ts, src/ui/text-input-dialog.ts — Error constants → getter functions
   • src/taskpane/status-context.ts — Context constants → getter functions
   • src/taskpane/status-popovers.ts — Level labels/hints → getter functions
   • src/extensions/permissions.ts — Capability descriptors → getter function

2. Missing imports — Added import { t } where it was missing:

   • src/ui/files-dialog-filtering.ts
   • src/ui/files-dialog.ts
   • src/ui/files-dialog-status.ts
   • src/compat/thinking-duration.ts
   • src/workbook/context.ts
   • src/commands/builtins/rules-overlay.ts

3. Hardcoded relative date — src/commands/builtins/overlay-relative-date.ts and src/ui/files-dialog.ts had hardcoded "just now", "m ago", "h ago" strings → made translatable

4. Execution mode toast — src/execution/controller.ts had `${label} mode.` hardcoded → made translatable

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Testing

• npm run dev — Dev server starts successfully (HTTP 200)
• git diff --stat — 78 files changed, 3365 insertions, 1144 deletions
• Pre-existing lint errors (22 in files-dialog-actions.ts and render-csv-table.ts) are upstream issues, not introduced here

Manual Verification

1. Load the taskpane → welcome screen shows in English (default)
2. Click "中文" button → page reloads → UI switches to Chinese
3. Settings → Advanced → Change language → works both ways
4. All major UI sections verified: sidebar, settings, dialogs, shortcuts, extensions hub, file dialog
5. Error toasts show Chinese prefix where applicable

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Adding a New Language

Adding another language requires only:

1. Create src/language/locales/{lang}.json with all keys translated
2. Import it in src/language/index.ts
3. Add the option to the language selectors

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Screenshots

(Add screenshots showing: English welcome page, Chinese welcome page, language selector in Settings)

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中文版本

摘要

此 PR 为 Pi for Excel 添加了轻量级国际化（i18n）系统和完整的简体中文（zh-CN）翻译。

动机： Pi for Excel 在中国拥有日益增长的用户群。此前所有 UI 文本均硬编码为英文，非英语用户无法直接使用。此 PR 引入了一个零第三方依赖的翻译框架，并提供开箱即用的完整中文本地化。

架构

翻译系统位于 src/language/，包含：

• index.ts — t() 翻译函数、initLanguage() 初始化、getLanguage() 获取当前语言
• locales/en.json — 英文原文（约 900 条，作为兜底）
• locales/zh-CN.json — 中文翻译（约 900 条）

设计原则：不引入任何 i18n 第三方库，对 Office WebView 保持零包体积增长。英文为兜底语言，未翻译的 key 自动显示英文原文。

语言切换

两种方式：

1. 欢迎页右上角的 English / 中文切换按钮
2. 设置 → 高级 → 语言 下拉选择框

切换后保存到 settings.language 并自动刷新页面。

文件变更

• 4 个新文件：翻译系统 + 中文文档
• 74 个修改文件：覆盖全部 UI 组件、对话框、命令、后端逻辑

关键修复

• 修复了模块级 t() 调用在 initLanguage() 之前执行的时序问题（7 处）
• 修复了多处缺少 import { t } 导致的运行时错误
• 将硬编码的日期格式化字符串（"just now"、"5m ago" 等）改为可翻译

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[smryyyyy]

Simply put
I have used a Chinese version for myself
Maybe you can add them together?
ovo