diff --git a/.github/workflows/pr-preview.yml b/.github/workflows/pr-preview.yml
new file mode 100644
index 0000000..bfd2897
--- /dev/null
+++ b/.github/workflows/pr-preview.yml
@@ -0,0 +1,69 @@
+name: PR Preview (same-repository branches)
+
+on:
+  pull_request:
+    types: [opened, reopened, synchronize, closed]
+
+permissions: {}
+
+concurrency:
+  group: pr-preview-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  explain-fork-limit:
+    name: Explain fork preview limitation
+    if: github.event.pull_request.head.repo.full_name != github.repository
+    permissions:
+      contents: read
+    runs-on: ubuntu-latest
+    steps:
+      - name: Record why deployment is skipped
+        run: echo "Fork preview deployment is intentionally disabled because pull_request workflows cannot safely grant write credentials to untrusted fork code."
+
+  deploy-preview:
+    name: Deploy same-repository web preview
+    if: github.event.pull_request.head.repo.full_name == github.repository
+    permissions:
+      contents: write
+      deployments: read
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.action == 'closed' && github.event.pull_request.base.sha || github.event.pull_request.head.sha }}
+
+      - name: Set up Node.js
+        if: github.event.action != 'closed'
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20.20.2
+          cache: npm
+          cache-dependency-path: frontend/package-lock.json
+
+      - name: Install frontend dependencies
+        if: github.event.action != 'closed'
+        working-directory: frontend
+        run: npm ci
+
+      - name: Export interactive web preview
+        if: github.event.action != 'closed'
+        working-directory: frontend
+        env:
+          EXPO_PUBLIC_USE_FAKE_WS: 'true'
+          EXPO_PUBLIC_WS_URL: ''
+          TIMEFLOW_PREVIEW_BASE_URL: /${{ github.event.repository.name }}/pr-preview/pr-${{ github.event.number }}
+        run: npx expo export --platform web --dev --output-dir dist
+
+      - name: Deploy preview and comment on PR
+        uses: rossjrw/pr-preview-action@ffa7509e91a3ec8dfc2e5536c4d5c1acdf7a6de9 # v1.8.1
+        with:
+          source-dir: frontend/dist
+          preview-branch: gh-pages
+          umbrella-dir: pr-preview
+          action: auto
+          wait-for-pages-deployment: true
+          comment: true
+          qr-code: true
diff --git a/README.md b/README.md
index c6c9ff9..aafa9c8 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1 @@
 # TimeFlow
-
-## Frontend map setup
-
-Copy `frontend/.env.example` to `frontend/.env` and set
-`EXPO_PUBLIC_BAIDU_MAP_AK` to a Baidu Maps browser-side AK. Enable JavaScript
-API v4 for that AK in the Baidu Maps console and add the development and
-production web origins to its Referer whitelist. Native builds render the
-same JavaScript API in a WebView, so its configured `baseUrl`
-(`https://timeflow.local/`) must also be allowed by the AK configuration.
diff --git a/frontend/.env.example b/frontend/.env.example
index 29e7b6f..9ecc315 100644
--- a/frontend/.env.example
+++ b/frontend/.env.example
@@ -10,7 +10,7 @@ EXPO_PUBLIC_BAIDU_MAP_AK=your-baidu-map-browser-ak
 # Emulator example: ws://10.0.2.2:8000/ws/v1
 # Production example: wss://api.example.com/ws
 # Release builds require wss://. Plain ws:// is accepted only in development.
-# Leave empty to use the in-process fake transport in development.
+
 EXPO_PUBLIC_WS_URL=
 
 # Force the fake WebSocket even if EXPO_PUBLIC_WS_URL is set (dev only).
diff --git a/frontend/app.config.js b/frontend/app.config.js
new file mode 100644
index 0000000..6336807
--- /dev/null
+++ b/frontend/app.config.js
@@ -0,0 +1,13 @@
+module.exports = ({ config }) => {
+  const previewBaseUrl = process.env.TIMEFLOW_PREVIEW_BASE_URL?.trim();
+
+  if (!previewBaseUrl) return config;
+
+  return {
+    ...config,
+    experiments: {
+      ...config.experiments,
+      baseUrl: previewBaseUrl,
+    },
+  };
+};