feat(i18n): add Simplified Chinese to the interface and prompt languages

CHANGELOG.md

@@ -17,6 +17,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   selection or a file. `lich sessions --json` and `whoami --json` now also carry
   each session's `path` and `projectPath`, and `send --project` now takes a
   directory, as `lich --help` already said it did.
+- **Simplified Chinese (简体中文) joins the language settings.** Both Settings ›
+  Appearance pickers, the *Interface language* and the *Prompt language*, now
+  offer Simplified Chinese next to English, Brazilian Portuguese and
+  Spanish. A browser set to any Chinese variant picks it by default for the
+  interface.
 
 - **Two language settings, English and Brazilian Portuguese.** Settings ›
   Appearance now has an *Interface language* for lich's own screens and a

docs/hooks/README.md

@@ -90,7 +90,7 @@ release before it did.
 
 `LICH_PROMPT_LANG` is the seventh, set on every session with a transport: the
 language the user picked for the text lich hands agents (Settings, "Prompt
-language"), as a BCP 47 tag: `en`, `pt-BR` or `es` today. Anything that composes text
+language"), as a BCP 47 tag: `en`, `pt-BR`, `es` or `zh-CN` today. Anything that composes text
 an agent reads from inside the session (the `lich` CLI, its MCP server, a hook)
 writes it in this language. An absent or unknown tag means English, so a plugin
 older or newer than the lich it runs under keeps working. It is read at spawn:

frontend/src/components/common/Trans.test.tsx

@@ -1,6 +1,7 @@
 import { renderToStaticMarkup } from "react-dom/server"
 import { afterEach, describe, expect, it, vi } from "vitest"
 import { resetLocale, setLocale } from "@/lib/i18n/i18n"
+import { zhCN } from "@/lib/i18n/locales/zh-cn"
 import { Trans } from "./Trans"
 
 afterEach(() => {
@@ -29,4 +30,11 @@ describe("Trans", () => {
     const html = renderToStaticMarkup(<Trans k="common.count.file" params={{ count: 2 }} />)
     expect(html).toBe("2 archivos")
   })
+
+  it("renders Simplified Chinese", () => {
+    vi.stubGlobal("localStorage", { setItem: () => {}, getItem: () => null })
+    setLocale("zh-CN")
+    const html = renderToStaticMarkup(<Trans k="common.count.file" params={{ count: 2 }} />)
+    expect(html).toBe(zhCN.common.count.file.other.replace("{count}", "2"))
+  })
 })

frontend/src/lib/i18n/i18n.test.ts

@@ -12,6 +12,7 @@ import {
 import { en } from "./locales/en"
 import { es } from "./locales/es"
 import { ptBR } from "./locales/pt-br"
+import { zhCN } from "./locales/zh-cn"
 
 function stubStorage(initial: Record<string, string> = {}) {
   const data = new Map(Object.entries(initial))
@@ -102,6 +103,23 @@ describe("t", () => {
     expect(t("common.count.file", { count: 2 })).toBe("2 arquivos")
   })
 
+  it("renders Simplified Chinese with its single plural form", () => {
+    stubStorage()
+    setLocale("zh-CN")
+    const forms = zhCN.common.count.file
+    expect(forms.one).toBe(forms.other)
+    expect(t("common.count.file", { count: 1 })).toBe(forms.other.replace("{count}", "1"))
+    expect(t("common.count.file", { count: 0 })).toBe(forms.other.replace("{count}", "0"))
+    expect(t("common.action.cancel")).toBe(zhCN.common.action.cancel)
+    expect(t("common.action.cancel")).not.toBe("Cancel")
+  })
+
+  it("matches any Chinese browser language to zh-CN", () => {
+    expect(matchLocale("zh-CN")).toBe("zh-CN")
+    expect(matchLocale("zh")).toBe("zh-CN")
+    expect(matchLocale("zh-Hans-CN")).toBe("zh-CN")
+  })
+
   it("rejects misuse at compile time", () => {
     // @ts-expect-error a key that does not exist
     expect(() => t("sidebar.nothing.here")).toThrow()
@@ -135,7 +153,7 @@ const placeholders = (text: string) => [...text.matchAll(/\{(\w+)\}/g)].map((m)
 // translation that renames, drops or invents a placeholder.
 describe("every locale against English", () => {
   const source = leaves(en as unknown as Tree)
-  const locales = { "pt-BR": ptBR, es }
+  const locales = { "pt-BR": ptBR, es, "zh-CN": zhCN }
 
   it("covers every locale the picker offers", () => {
     expect(Object.keys(locales)).toEqual(LOCALES.filter((locale) => locale !== "en"))

frontend/src/lib/i18n/i18n.ts

@@ -4,14 +4,15 @@ import type { At, ParamsArg, PluralForms, Shape } from "./catalog"
 import { en, type MessageKey, type Messages } from "./locales/en"
 import { es } from "./locales/es"
 import { ptBR } from "./locales/pt-br"
+import { zhCN } from "./locales/zh-cn"
 
 // The interface language. It is a page preference, not a workspace setting:
 // it changes nothing the backend does, so it lives in localStorage like the
 // theme. The language of the text lich types into agent sessions is a separate
 // setting on purpose (prompt-language-store.ts, internal/prompt): people often
 // run the interface in one language and talk to their agents in another.
 
-export const LOCALES = ["en", "pt-BR", "es"] as const
+export const LOCALES = ["en", "pt-BR", "es", "zh-CN"] as const
 export type Locale = (typeof LOCALES)[number]
 
 /** Each language named in itself, which is how someone who cannot read the
@@ -20,9 +21,10 @@ export const LOCALE_NAMES: Record<Locale, string> = {
   en: "English",
   "pt-BR": "Português (Brasil)",
   es: "Español",
+  "zh-CN": "简体中文",
 }
 
-const CATALOGS: Record<Locale, Shape<Messages>> = { en, "pt-BR": ptBR, es }
+const CATALOGS: Record<Locale, Shape<Messages>> = { en, "pt-BR": ptBR, es, "zh-CN": zhCN }
 
 export const UI_LANGUAGE_PREF = "lich.appearance.language"
 

frontend/src/lib/i18n/lib-messages.test.ts

@@ -63,4 +63,13 @@ describe("messages built in plain modules follow the language", () => {
     setLocale("pt-BR")
     expect(formatAge(5 * 60_000)).toBe("5 min")
   })
+
+  it("formats units and ages for Simplified Chinese", () => {
+    setLocale("zh-CN")
+    expect(COST_MISS_REASON["mixed-models"]).toMatch(/[\u4e00-\u9fff]/)
+    expect(formatAge(5 * 60_000)).toMatch(/^5\s?(分|min)/)
+    const now = new Date(2026, 0, 5, 12, 0, 0)
+    const at = Math.floor(now.getTime() / 1000) + 45 * 60
+    expect(timeUntil(at, now)).toContain("45")
+  })
 })

frontend/src/lib/i18n/locales/zh-cn/common.ts

@@ -0,0 +1,43 @@
+import type { Shape } from "../../catalog"
+import type { common as en } from "../en/common"
+
+export const common = {
+  count: {
+    file: { one: "{count} 个文件", other: "{count} 个文件" },
+    commit: { one: "{count} 个提交", other: "{count} 个提交" },
+  },
+  time: {
+    justNow: "刚刚",
+  },
+  action: {
+    cancel: "取消",
+    save: "保存",
+    create: "创建",
+  },
+  checkAgainButton: {
+    check: "重新检查",
+    checking: "正在检查…",
+  },
+  errorBoundary: {
+    stoppedRendering: "{label} 已停止渲染",
+    reload: "重新加载窗口",
+    retry: "重试",
+  },
+  stepper: {
+    default: "默认",
+  },
+  toolMissing: {
+    notInstalled: "未安装 {label}",
+    install: "安装 {bin}",
+  },
+  pickerDialog: {
+    navigate: "导航",
+    filter: "筛选",
+    close: "关闭",
+  },
+  ui: {
+    dialog: {
+      close: "关闭",
+    },
+  },
+} satisfies Shape<typeof en>

frontend/src/lib/i18n/locales/zh-cn/diff.ts

@@ -0,0 +1,88 @@
+import type { Shape } from "../../catalog"
+import type { diff as en } from "../en/diff"
+
+export const diff = {
+  binaryPreview: {
+    before: "之前",
+    after: "之后",
+    added: "已添加",
+    deleted: "已删除",
+    binary: "二进制文件",
+    binaryNoPreview: "二进制文件 · 此文件类型无法预览",
+    loading: "正在加载…",
+    missing: "不在此修订中",
+    pdfSide: "选择显示 PDF 的哪一侧",
+  },
+  commentBatch: {
+    openSession: "打开一个会话，将这些评论发送给它",
+    removeComment: "移除评论",
+    notePlaceholder: "关于整个更改的备注…",
+    noteLabel: "关于整个更改的备注",
+    count: { one: "{count} 条评论", other: "{count} 条评论" },
+    clear: "清空",
+    send: "发送",
+  },
+  diffBulk: {
+    collapseAll: "折叠所有文件",
+    expandAll: "展开所有文件",
+    showWhitespace: "显示空白字符更改",
+    hideWhitespace: "隐藏空白字符更改",
+  },
+  discardDialog: {
+    title: "放弃更改",
+    description: "要还原 {path} 的所有未提交更改吗？此操作无法撤销。",
+    descriptionAdded: "要还原 {path} 的所有未提交更改吗？该文件将从磁盘中删除。此操作无法撤销。",
+    confirm: "放弃更改",
+  },
+  injectMenu: {
+    injectFile: "注入文件",
+    injectLines: "注入行",
+    injectLinesRange: "注入行 {lines}",
+    sessionComment: "给会话的评论…",
+    sessionCommentRange: "给会话的评论 {lines}…",
+    reviewComment: "对拉取请求的评论…",
+    reviewCommentRange: "对拉取请求的评论 {lines}…",
+    revertSelected: "还原所选行",
+    revert: { one: "还原 {count} 行更改", other: "还原 {count} 行更改" },
+  },
+  fileDiff: {
+    readFailed: "无法读取 {path}",
+    whitespaceOnly: "仅空白字符",
+    onlyWhitespaceChanged: "仅空白字符发生了更改",
+    addAsContext: "将文件添加为上下文",
+    discard: "放弃更改",
+    viewed: "已查看",
+  },
+  reviewPanel: {
+    lastTurnHint: "上一轮运行期间磁盘上发生的更改，包括格式化工具、编辑器或你自己所做的编辑。",
+    discardFailed: "放弃更改失败：{error}",
+    reverted: "已还原 {name} 中的 +{added} -{deleted}",
+    undo: "撤销",
+    undoFailed: "无法撤销对 {name} 的还原",
+    revertFailed: "无法还原 {name} 中的行",
+    said: "说",
+    sourceLabel: "选择要显示的更改",
+    workingTree: "工作区",
+    lastTurn: "上一轮",
+    ended: "{age}前结束",
+    turnReadFailed: "无法读取上一轮",
+    notRepository: "不是 git 仓库",
+    loading: "正在加载…",
+    emptyTitle: "此时间窗口内没有任何更改。",
+    emptyBody: "上一轮开始到结束期间，磁盘上没有文件发生变化。",
+    unrecordedTitle: "没有记录上一轮。",
+    unrecordedBody: "一轮在此结束后，这里会显示内容。",
+    lostTitle: "这一轮的记录已丢失。",
+    lostBody: "一轮在此结束，但 lich 无法为它保存检出的快照。下一轮会照常记录。",
+    noChanges: "没有未提交的更改",
+    squeezed: "并排视图需要更宽的面板",
+  },
+  reviewSlots: {
+    forSession: "给会话 · {lines}",
+    onPullRequest: "对拉取请求 · {lines}",
+    addToBatch: "添加到批次",
+    addToReview: "添加到审查",
+    sessionPlaceholder: "这里应该改什么？它会连同其他内容一起发送给会话。",
+    reviewPlaceholder: "留下评论。提交审查时一并发送。",
+  },
+} satisfies Shape<typeof en>

frontend/src/lib/i18n/locales/zh-cn/dock.ts

@@ -0,0 +1,37 @@
+import type { Shape } from "../../catalog"
+import type { dock as en } from "../en/dock"
+
+export const dock = {
+  rightDock: {
+    fileBrowser: "文件浏览器",
+    reviewChanges: "审查更改",
+    tabCode: "代码",
+    tabReview: "审查",
+    exitFullScreen: "退出全屏",
+    fullScreen: "全屏",
+    closePanel: "关闭面板",
+    fileTree: "文件树",
+    reviewPanel: "审查面板",
+    resizePanel: "调整面板大小",
+  },
+  searchResults: {
+    prompt: "搜索此检出中每个文件的文本",
+    searching: "正在搜索…",
+    noMatch: "没有文件包含“{query}”",
+  },
+  filesPanel: {
+    searchPlaceholder: "在文件中搜索",
+    filterPlaceholder: "按名称筛选",
+    searchLabel: "在文件中搜索",
+    filterLabel: "按名称筛选文件",
+    matchesLabel: "输入框匹配的内容",
+    byName: "名称",
+    byText: "文本",
+    readFailed: "无法读取此文件夹",
+    loading: "正在加载…",
+    noMatch: "没有匹配的文件",
+    empty: "这里没有文件",
+    backToTree: "返回文件树",
+    readOnly: "只读",
+  },
+} satisfies Shape<typeof en>

frontend/src/lib/i18n/locales/zh-cn/env.ts

@@ -0,0 +1,58 @@
+import type { Shape } from "../../catalog"
+import type { env as en } from "../en/env"
+
+export const env = {
+  providerSummary: {
+    installed: "已安装",
+    installedCustomPath: "已安装 · 自定义路径",
+    signedOut: "已登出",
+    windowPercent: "{length} 窗口的 {percent}%",
+    percentUsed: "已用 {percent}%",
+  },
+  quota: {
+    tokenLogin: "令牌登录",
+    weekShort: "周",
+  },
+  paths: {
+    cwdUnknown: "工作目录未知 · 位于 {host} 内",
+  },
+  sandbox: {
+    windowsReason: "lich 在 Windows 上没有沙箱后端",
+    windowsAdvice: "无需安装任何东西，每个会话都直接在本机上运行。",
+    macReason: "sandbox-exec 不可用",
+    macAdvice:
+      "macOS 自带 /usr/bin/sandbox-exec，所以缺少可用的 sandbox-exec 意味着系统已损坏，lich 无法修复。每个会话都直接在本机上运行。",
+    linuxReason: "未安装 bubblewrap",
+    linuxAdvice: "请安装 bubblewrap 并重新打开 lich。在此之前，每个会话都直接在本机上运行。",
+    confinedMeans:
+      "一个只包含智能体自身状态的空主目录，本机只读，只能写入其检出目录内部。网络保持开启。",
+  },
+  vcsTools: {
+    gitWithout: "没有它，分支、差异和工作树都将为空。",
+    ghWithout: "没有它，无法使用拉取请求、检查和 PR 检出。",
+  },
+  binary: {
+    parkedProject: "{name} 覆盖已关闭",
+    parkedProjectFallback: "项目",
+    parkedGlobal: "全局覆盖已关闭",
+    executable: "可执行",
+    noSuchFile: "文件不存在",
+    notOnPath: "不在 $PATH 中",
+    notExecutable: "不可执行",
+    homeNotExpanded: "~ 不会被展开",
+    relativePath: "相对路径",
+    detailHomeShortcut:
+      "lich 直接启动该二进制文件，因此 ~ 按字面处理而不会被展开。请使用完整路径。",
+    detailRelative:
+      "相对路径会按每个会话自己的工作目录解析，因此每个会话指向的二进制文件各不相同。请使用完整路径。",
+    detailBroken: "问题解决之前，会话无法启动。你也可以关闭或清除覆盖设置，回退到下一层的配置。",
+  },
+  commitIdentity: {
+    noneLead: "此检出中没有 git 身份。",
+    noneNote: "在设置 user.email 之前，提交将被拒绝。",
+    landAsNamed: "提交将以 {name} 的身份记录",
+    landAs: "提交将以以下身份记录",
+    setLocal: "，在此仓库中设置，覆盖你的全局配置。",
+    setGlobal: "，来自 git user.email，而非此账户。",
+  },
+} satisfies Shape<typeof en>

frontend/src/lib/i18n/locales/zh-cn/footer.ts

@@ -0,0 +1,19 @@
+import type { Shape } from "../../catalog"
+import type { footer as en } from "../en/footer"
+
+export const footer = {
+  item: {
+    attach: { label: "附加文件", example: "附加文件" },
+    files: { label: "文件资源管理器", example: "文件" },
+    changes: { label: "更改" },
+    pr: { label: "拉取请求" },
+    checkout: { label: "分支" },
+    path: { label: "工作目录" },
+    model: { label: "模型", example: "模型" },
+    context: { label: "上下文窗口" },
+    plan: { label: "套餐用量" },
+    cost: { label: "费用" },
+    handsOn: { label: "实际操作时间" },
+    clock: { label: "日期和时间" },
+  },
+} satisfies Shape<typeof en>