feat: add loading state management to ListDetailViewModel and display loading overlay in ListDetailScreen

CollabTableAndroid/app/src/main/java/com/collabtable/app/ui/screens/ListDetailScreen.kt

@@ -121,6 +121,7 @@ fun ListDetailScreen(
     val list by viewModel.list.collectAsState()
     val fields by viewModel.fields.collectAsState()
     val items by viewModel.items.collectAsState()
+    val isLoading by viewModel.isLoading.collectAsState()
 
     // Use derivedStateOf to create stable references
     val stableFields by remember { derivedStateOf { fields } }
@@ -239,15 +240,18 @@ fun ListDetailScreen(
 
         val processedItems = transformed.processed
         val groupedItems = transformed.grouped
-        if (stableFields.isEmpty()) {
+        // Root container to allow loading overlay
         Box(
             modifier =
                 Modifier
                     .fillMaxSize()
                     .padding(padding),
-                contentAlignment = Alignment.Center,
         ) {
-                Column(horizontalAlignment = Alignment.CenterHorizontally) {
+            if (stableFields.isEmpty()) {
+                Column(
+                    modifier = Modifier.align(Alignment.Center),
+                    horizontalAlignment = Alignment.CenterHorizontally,
+                ) {
                     Text(
                         text = "No fields yet. Add fields to get started!",
                         style = MaterialTheme.typography.bodyLarge,
@@ -260,13 +264,11 @@ fun ListDetailScreen(
                         Text(stringResource(R.string.add_field))
                     }
                 }
-            }
             } else {
                 Column(
                     modifier =
                         Modifier
-                        .fillMaxSize()
+                            .fillMaxSize(),
-                        .padding(padding),
                 ) {
                 // Filter/Sort/Group Controls - Always visible above table
                 Row(
@@ -560,6 +562,17 @@ fun ListDetailScreen(
                                     )
                                 }
                             }
+
+                            // Loading overlay during initial content load
+                            if (isLoading) {
+                                Box(
+                                    modifier = Modifier.fillMaxSize(),
+                                    contentAlignment = Alignment.Center,
+                                ) {
+                                    androidx.compose.material3.CircularProgressIndicator()
+                                }
+                            }
+                        }
                         }
 
                         // Items list below the fixed header

CollabTableAndroid/app/src/main/java/com/collabtable/app/ui/screens/ListDetailViewModel.kt

@@ -34,6 +34,9 @@ class ListDetailViewModel(
     private val _items = MutableStateFlow<List<ItemWithValues>>(emptyList())
     val items: StateFlow<List<ItemWithValues>> = _items.asStateFlow()
 
+    private val _isLoading = MutableStateFlow(true)
+    val isLoading: StateFlow<Boolean> = _isLoading.asStateFlow()
+
     private val syncRepository = SyncRepository(context)
 
     init {
@@ -42,6 +45,15 @@ class ListDetailViewModel(
     }
 
     private fun loadListData() {
+        // Track first emissions to flip loading off after initial data is ready
+        var hasList = false
+        var hasFields = false
+        var hasItems = false
+        fun maybeLoaded() {
+            if (hasList && hasFields && hasItems) {
+                _isLoading.value = false
+            }
+        }
         viewModelScope.launch {
             database
                 .listDao()
@@ -49,6 +61,10 @@ class ListDetailViewModel(
                 .debounce(75)
                 .collect { listWithFields ->
                     _list.value = listWithFields?.list
+                    if (!hasList) {
+                        hasList = true
+                        maybeLoaded()
+                    }
                 }
         }
 
@@ -59,6 +75,10 @@ class ListDetailViewModel(
                 .debounce(75)
                 .collect { itemsData ->
                     _items.value = itemsData
+                    if (!hasItems) {
+                        hasItems = true
+                        maybeLoaded()
+                    }
                 }
         }
 
@@ -69,6 +89,10 @@ class ListDetailViewModel(
                 .debounce(75)
                 .collect { fieldsData ->
                     _fields.value = fieldsData
+                    if (!hasFields) {
+                        hasFields = true
+                        maybeLoaded()
+                    }
                 }
         }
     }