feat(data-connect): Implement caching for business ID and enhance error handling in DataConnectService

apps/mobile/packages/data_connect/lib/src/services/data_connect_service.dart

@@ -27,6 +27,9 @@ class DataConnectService with DataErrorHandler {
   /// Cache for the current staff ID to avoid redundant lookups.
   String? _cachedStaffId;
 
+  /// Cache for the current business ID to avoid redundant lookups.
+  String? _cachedBusinessId;
+
   /// Gets the current staff ID from session store or persistent storage.
   Future<String> getStaffId() async {
     // 1. Check Session Store
@@ -41,15 +44,14 @@ class DataConnectService with DataErrorHandler {
     // 3. Fetch from Data Connect using Firebase UID
     final firebase_auth.User? user = _auth.currentUser;
     if (user == null) {
-      throw Exception('User is not authenticated');
+      throw const NotAuthenticatedException(
+        technicalMessage: 'User is not authenticated',
+      );
     }
 
     try {
-      final fdc.QueryResult<
-        dc.GetStaffByUserIdData,
-        dc.GetStaffByUserIdVariables
-      >
-      response = await executeProtected(
+      final fdc.QueryResult<dc.GetStaffByUserIdData, dc.GetStaffByUserIdVariables>
+          response = await executeProtected(
         () => connector.getStaffByUserId(userId: user.uid).execute(),
       );
 
@@ -65,6 +67,30 @@ class DataConnectService with DataErrorHandler {
     return user.uid;
   }
 
+  /// Gets the current business ID from session store or persistent storage.
+  Future<String> getBusinessId() async {
+    // 1. Check Session Store
+    final dc.ClientSession? session = dc.ClientSessionStore.instance.session;
+    if (session?.business?.id != null) {
+      return session!.business!.id;
+    }
+
+    // 2. Check Cache
+    if (_cachedBusinessId != null) return _cachedBusinessId!;
+
+    // 3. Check Auth Status
+    final firebase_auth.User? user = _auth.currentUser;
+    if (user == null) {
+      throw const NotAuthenticatedException(
+        technicalMessage: 'User is not authenticated',
+      );
+    }
+
+    // 4. Fallback (should ideally not happen if DB is seeded and session is initialized)
+    // Ideally we'd have a getBusinessByUserId query here.
+    return user.uid;
+  }
+
   /// Converts a Data Connect timestamp/string/json to a [DateTime].
   DateTime? toDateTime(dynamic t) {
     if (t == null) return null;
@@ -116,5 +142,6 @@ class DataConnectService with DataErrorHandler {
   /// Clears the internal cache (e.g., on logout).
   void clearCache() {
     _cachedStaffId = null;
+    _cachedBusinessId = null;
   }
 }