diff --git a/.woodpecker/dev-image.yml b/.woodpecker/dev-image.yml
index c4e3c9b..aac864e 100644
--- a/.woodpecker/dev-image.yml
+++ b/.woodpecker/dev-image.yml
@@ -41,9 +41,11 @@ steps:
       - printf '%s' "$ZOT_SECRET" | buildah login --tls-verify=true --username "$ZOT_USERNAME" --password-stdin "$ZOT_REGISTRY"
       - trap 'buildah logout "$ZOT_REGISTRY" >/dev/null 2>&1 || true' EXIT
       - sha="${CI_COMMIT_SHA:0:7}"
+      - build_tag="dev-$sha"
       - image="$ZOT_REGISTRY/justme/webdrop-api:dev-$sha"
       - dev_image="$ZOT_REGISTRY/justme/webdrop-api:dev"
-      - buildah bud --layers --network host --format docker --platform linux/amd64 --tag "$image" --file server/Dockerfile .
+      - build_time="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
+      - buildah bud --layers --network host --format docker --platform linux/amd64 --build-arg "WEBDROP_BUILD_COMMIT=$CI_COMMIT_SHA" --build-arg "WEBDROP_BUILD_TAG=$build_tag" --build-arg "WEBDROP_BUILD_TIME=$build_time" --tag "$image" --file server/Dockerfile .
       - buildah tag "$image" "$dev_image"
       - buildah push "$image" "docker://$image"
       - buildah push "$dev_image" "docker://$dev_image"
diff --git a/.woodpecker/release-backend.yml b/.woodpecker/release-backend.yml
index 82cf4dd..e9e437a 100644
--- a/.woodpecker/release-backend.yml
+++ b/.woodpecker/release-backend.yml
@@ -56,7 +56,9 @@ steps:
       - trap 'buildah logout "$ZOT_REGISTRY" >/dev/null 2>&1 || true' EXIT
       - image="$ZOT_REGISTRY/justme/webdrop-api:$release_tag"
       - latest_image="$ZOT_REGISTRY/justme/webdrop-api:latest"
-      - buildah bud --layers --network host --format docker --platform linux/amd64 --tag "$image" --file server/Dockerfile .
+      - build_commit="$(git rev-parse HEAD)"
+      - build_time="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
+      - buildah bud --layers --network host --format docker --platform linux/amd64 --build-arg "WEBDROP_BUILD_COMMIT=$build_commit" --build-arg "WEBDROP_BUILD_TAG=$release_tag" --build-arg "WEBDROP_BUILD_TIME=$build_time" --tag "$image" --file server/Dockerfile .
       - buildah tag "$image" "$latest_image"
       - buildah push "$image" "docker://$image"
       - buildah push "$latest_image" "docker://$latest_image"
diff --git a/docs/frontend.md b/docs/frontend.md
index ec7446e..eb0a1ac 100644
--- a/docs/frontend.md
+++ b/docs/frontend.md
@@ -20,6 +20,8 @@
 
 **依赖策略**:新增运行时依赖需要书面理由(解决什么、为何不能自写、体积)。不引入 UI 组件库、动画库、图标库、日期库。依赖越少,越容易审计;前端是整个方案的信任根。
 
+生产构建将 `web/package.json` 的版本和构建时注入的 commit、tag、UTC 时间编译进前端,首页右下角展示。部署构建通过 `WEBDROP_BUILD_COMMIT`、`WEBDROP_BUILD_TAG`、`WEBDROP_BUILD_TIME` 提供元数据;本地构建没有 CI 环境时尝试读取 Git,时间取本次构建时间。
+
 ## 2. 目录与分层
 
 ```
diff --git a/docs/ui-design.md b/docs/ui-design.md
index d71b596..3bff32b 100644
--- a/docs/ui-design.md
+++ b/docs/ui-design.md
@@ -138,6 +138,8 @@ WebDrop 是**暂存区**,不是聊天室:内容按类型与待办动作组织,
 
 首页把「临时分享」与「设备频道」作为两个并列入口:前者用于发一段临时文本或文件,后者用于多设备长期同步。
 
+主页右上角提供外观菜单,可跟随系统或切换亮色/暗色。右下角显示构建来源:前端包版本、构建 tag、commit 与 UTC 构建时间;这些值来自构建环境,无法取得时如实显示「未标记」或「未知」。
+
 ```
 ┌──────────────────────────────────┐
 │            WebDrop               │
diff --git a/server/Dockerfile b/server/Dockerfile
index 5ab9373..c91bc7e 100644
--- a/server/Dockerfile
+++ b/server/Dockerfile
@@ -5,6 +5,12 @@ COPY packages/core/package.json ./packages/core/package.json
 RUN cd web && npm ci --no-audit --no-fund
 COPY packages/core/ ./packages/core/
 COPY web/ ./web/
+ARG WEBDROP_BUILD_COMMIT=unknown
+ARG WEBDROP_BUILD_TAG=unknown
+ARG WEBDROP_BUILD_TIME=unknown
+ENV WEBDROP_BUILD_COMMIT=$WEBDROP_BUILD_COMMIT \
+    WEBDROP_BUILD_TAG=$WEBDROP_BUILD_TAG \
+    WEBDROP_BUILD_TIME=$WEBDROP_BUILD_TIME
 RUN npm run build --prefix web
 
 FROM mcr.microsoft.com/dotnet/sdk:10.0-noble-aot AS build
diff --git a/web/src/build-info.d.ts b/web/src/build-info.d.ts
new file mode 100644
index 0000000..a3e91f3
--- /dev/null
+++ b/web/src/build-info.d.ts
@@ -0,0 +1,6 @@
+declare const __WEBDROP_BUILD_INFO__: {
+  readonly frontendVersion: string;
+  readonly commit: string;
+  readonly tag: string;
+  readonly builtAt: string;
+};
diff --git a/web/src/features/home/Home.module.css b/web/src/features/home/Home.module.css
index 9b7f71c..36843ac 100644
--- a/web/src/features/home/Home.module.css
+++ b/web/src/features/home/Home.module.css
@@ -6,13 +6,38 @@
   animation: page-in 0.21s ease-out;
 }
 
+.appearance {
+  position: fixed;
+  z-index: 30;
+  top: max(var(--space-4), env(safe-area-inset-top));
+  right: max(var(--space-4), env(safe-area-inset-right));
+}
+
+.buildInfo {
+  position: fixed;
+  z-index: 1;
+  right: max(var(--space-4), env(safe-area-inset-right));
+  bottom: max(var(--space-3), env(safe-area-inset-bottom));
+  display: flex;
+  flex-wrap: wrap;
+  justify-content: flex-end;
+  gap: var(--space-1) var(--space-3);
+  max-width: calc(100vw - var(--space-6));
+  color: var(--text-dim);
+  font-family: var(--font-mono);
+  font-size: 11px;
+  line-height: 1.5;
+  text-align: right;
+  pointer-events: none;
+}
+
 .main {
   display: flex;
   flex-direction: column;
   gap: var(--space-4);
   max-width: 860px;
   margin: 0 auto;
-  padding: var(--space-6) var(--space-4);
+  padding: var(--space-6) var(--space-4) calc(var(--space-6) + 32px);
 }
 
 .head {
diff --git a/web/src/features/home/Home.tsx b/web/src/features/home/Home.tsx
index 55813eb..4a3c9ab 100644
--- a/web/src/features/home/Home.tsx
+++ b/web/src/features/home/Home.tsx
@@ -1,5 +1,6 @@
 import { lazy, Suspense, useCallback, useState } from 'react';
 import { channelPath, navigate, sharePath } from '@/app/navigation';
+import { buildInfo } from '@/lib/buildInfo';
 import type { ChannelInfo, Share } from '@/core-bridge/types';
 import type { ClipboardPayload } from '@/lib/clipboard';
 import { useGlobalPaste } from '@/lib/useGlobalPaste';
@@ -8,6 +9,7 @@ import { useShares } from '@/store/shares';
 import { solveCreationCaptcha } from '@/core-bridge/captcha';
 import { errorMessage } from '@/core-bridge/errors';
 import { Button } from '@/ui/Button';
+import { ThemeMenu } from '@/ui/ThemeMenu';
 import { ChannelList } from './ChannelList';
 import { CreateSheet } from './CreateSheet';
 import { QuickShare } from './QuickShare';
@@ -58,6 +60,7 @@ export function Home() {
 
   return (
     <div className={styles.page}>
+      <div className={styles.appearance}><ThemeMenu /></div>
       <main className={styles.main}>
         <header className={styles.head}>
           <h1 className={styles.logo}>WebDrop</h1>
@@ -95,6 +98,13 @@ export function Home() {
         ) : null}
       </main>
 
+      <aside className={styles.buildInfo} aria-label="构建信息">
+        <span>前端 v{buildInfo.frontendVersion}</span>
+        <span>tag {buildInfo.tag && buildInfo.tag !== 'unknown' ? buildInfo.tag : '未标记'}</span>
+        <span>commit {buildInfo.commit}</span>
+        <time dateTime={buildInfo.builtAt}>{buildInfo.builtAt} UTC</time>
+      </aside>
+
       {createOpen ? <CreateSheet onClose={() => setCreateOpen(false)} onCreated={open} /> : null}
       <Suspense fallback={null}>
         {scanOpen ? <ScanSheet onClose={() => setScanOpen(false)} onChannel={open} onShare={open} /> : null}
diff --git a/web/src/lib/buildInfo.ts b/web/src/lib/buildInfo.ts
new file mode 100644
index 0000000..c5380bc
--- /dev/null
+++ b/web/src/lib/buildInfo.ts
@@ -0,0 +1 @@
+export const buildInfo = __WEBDROP_BUILD_INFO__;
diff --git a/web/vite.config.ts b/web/vite.config.ts
index 822401c..779bdb1 100644
--- a/web/vite.config.ts
+++ b/web/vite.config.ts
@@ -1,9 +1,30 @@
+import { execFileSync } from 'node:child_process';
+import { readFileSync } from 'node:fs';
 import { fileURLToPath } from 'node:url';
 import react from '@vitejs/plugin-react';
 import { defineConfig } from 'vitest/config';
 
+const webRoot = fileURLToPath(new URL('.', import.meta.url));
+const webPackage = JSON.parse(readFileSync(new URL('./package.json', import.meta.url), 'utf8')) as { version: string };
+
+function gitValue(...args: string[]): string {
+  try {
+    return execFileSync('git', args, { cwd: webRoot, encoding: 'utf8', stdio: ['ignore', 'pipe', 'ignore'] }).trim() || 'unknown';
+  } catch {
+    return 'unknown';
+  }
+}
+
+const buildInfo = {
+  frontendVersion: webPackage.version,
+  commit: process.env.WEBDROP_BUILD_COMMIT ?? gitValue('rev-parse', '--short=12', 'HEAD'),
+  tag: process.env.WEBDROP_BUILD_TAG ?? gitValue('describe', '--tags', '--exact-match', 'HEAD'),
+  builtAt: process.env.WEBDROP_BUILD_TIME ?? new Date().toISOString(),
+};
+
 export default defineConfig({
   plugins: [react()],
+  define: { __WEBDROP_BUILD_INFO__: JSON.stringify(buildInfo) },
   resolve: {
     alias: {
       '@': fileURLToPath(new URL('./src', import.meta.url)),