接入移动端原生扫码能力

新增 scanner.scanQrCode HostBridge 契约与二维码结果归一。

接入 Expo Camera 扫码 overlay 并保留 H5 浏览器扫码回退。

让 Tauri 白名单识别扫码 method 但不声明桌面扫码能力。

同步原生壳门禁、Expo 权限检查、方案文档和共享决策记录。

apps/mobile-shell/src/shell/QrScannerOverlay.tsx

@@ -0,0 +1,141 @@
+import {
+  Camera,
+  CameraView,
+  type BarcodeScanningResult,
+} from 'expo-camera';
+import { useCallback, useEffect, useState } from 'react';
+import { Pressable, StyleSheet, Text, View } from 'react-native';
+
+import {
+  cancelQrCodeScan,
+  completeQrCodeScan,
+  failQrCodeScan,
+  subscribeQrScannerState,
+} from '../host-bridge/scanner';
+
+export function QrScannerOverlay() {
+  const [isActive, setIsActive] = useState(false);
+  const [requestKey, setRequestKey] = useState(0);
+  const [hasPermission, setHasPermission] = useState(false);
+  const [scanCompleted, setScanCompleted] = useState(false);
+
+  useEffect(() => subscribeQrScannerState((state) => {
+    setIsActive(state.active);
+    setRequestKey(state.requestKey);
+  }), []);
+
+  useEffect(() => {
+    if (!isActive) {
+      setHasPermission(false);
+      setScanCompleted(false);
+      return;
+    }
+
+    let disposed = false;
+    setHasPermission(false);
+    setScanCompleted(false);
+    void Camera.requestCameraPermissionsAsync()
+      .then((permission) => {
+        if (disposed) {
+          return;
+        }
+        if (!permission.granted) {
+          failQrCodeScan('camera permission denied');
+          return;
+        }
+        setHasPermission(true);
+      })
+      .catch(() => {
+        if (!disposed) {
+          failQrCodeScan('camera permission unavailable');
+        }
+      });
+
+    return () => {
+      disposed = true;
+    };
+  }, [isActive, requestKey]);
+
+  const handleBarcodeScanned = useCallback(
+    (result: BarcodeScanningResult) => {
+      if (scanCompleted || result.type !== 'qr') {
+        return;
+      }
+
+      if (completeQrCodeScan(result.data)) {
+        setScanCompleted(true);
+      }
+    },
+    [scanCompleted],
+  );
+
+  if (!isActive) {
+    return null;
+  }
+
+  return (
+    <View style={styles.root}>
+      {hasPermission ? (
+        <CameraView
+          style={styles.camera}
+          facing="back"
+          onBarcodeScanned={scanCompleted ? undefined : handleBarcodeScanned}
+          barcodeScannerSettings={{
+            barcodeTypes: ['qr'],
+          }}
+        />
+      ) : null}
+      <View pointerEvents="none" style={styles.frame} />
+      <Pressable
+        accessibilityRole="button"
+        accessibilityLabel="关闭扫码"
+        onPress={cancelQrCodeScan}
+        style={styles.closeButton}
+      >
+        <Text style={styles.closeButtonText}>关闭</Text>
+      </Pressable>
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  root: {
+    position: 'absolute',
+    top: 0,
+    right: 0,
+    bottom: 0,
+    left: 0,
+    backgroundColor: '#0c0a09',
+  },
+  camera: {
+    flex: 1,
+  },
+  frame: {
+    position: 'absolute',
+    top: '22%',
+    right: 42,
+    bottom: '22%',
+    left: 42,
+    borderWidth: 2,
+    borderColor: '#fffdf9',
+    borderRadius: 8,
+  },
+  closeButton: {
+    position: 'absolute',
+    top: 20,
+    right: 20,
+    minWidth: 76,
+    minHeight: 40,
+    alignItems: 'center',
+    justifyContent: 'center',
+    borderRadius: 8,
+    backgroundColor: '#fffdf9',
+    paddingHorizontal: 16,
+  },
+  closeButtonText: {
+    color: '#211a16',
+    fontSize: 15,
+    fontWeight: '700',
+    lineHeight: 20,
+  },
+});

apps/mobile-shell/src/shell/ShellApp.tsx

@@ -51,6 +51,7 @@ import {
   shouldBlockMobileWebViewNavigationRequest,
 } from './webViewPolicy';
 import { parseMobileWebViewHistoryStateMessage } from './webViewHistory';
+import { QrScannerOverlay } from './QrScannerOverlay';
 
 function buildHostBridgeMessageScript(message: unknown) {
   return `window.dispatchEvent(new MessageEvent('message', { data: ${JSON.stringify(
@@ -371,6 +372,7 @@ export default function ShellApp() {
             </Pressable>
           </View>
         ) : null}
+        <QrScannerOverlay />
       </SafeAreaView>
     </SafeAreaProvider>
   );