Expose ListInfo via UniFFI and rename state observers to listInfo observers

Complete the ListInfo refactoring through the entire stack:

Rust:
- Add uniffi::Record to ListInfo for Kotlin export
- Add list_info() method to PostMetadataCollectionWithEditContext
- Rename is_relevant_state_update() to is_relevant_list_info_update()
- Check both ListMetadata and ListMetadataState tables for list info changes

Kotlin wrapper:
- Add ListInfo.hasMorePages and ListInfo.isSyncing extensions
- Expose listInfo() method, remove individual accessors
- Rename stateObservers to listInfoObservers

Kotlin ViewModel:
- Store ListInfo directly in state instead of separate fields
- Derive isSyncing, hasMorePages, currentPage from listInfo
- Use addListInfoObserver for pagination + state changes

Observer split is now:
- Data observers: entity tables + list_metadata_items
- ListInfo observers: list_metadata + list_metadata_state

Author: oguzkocer

native/kotlin/api/kotlin/src/main/kotlin/rs/wordpress/cache/kotlin/ObservableMetadataCollection.kt

@@ -1,12 +1,29 @@
 package rs.wordpress.cache.kotlin
 
+import uniffi.wp_mobile.ListInfo
 import uniffi.wp_mobile.PostMetadataCollectionItem
 import uniffi.wp_mobile.PostMetadataCollectionWithEditContext
 import uniffi.wp_mobile.SyncResult
 import uniffi.wp_mobile_cache.ListState
 import uniffi.wp_mobile_cache.UpdateHook
 import java.util.concurrent.CopyOnWriteArrayList
 
+/**
+ * Check if there are more pages to load.
+ *
+ * Returns `true` if:
+ * - Total pages is unknown (assume more)
+ * - Current page is less than total pages
+ */
+val ListInfo.hasMorePages: Boolean
+    get() = totalPages?.let { currentPage < it } ?: true
+
+/**
+ * Check if a sync operation is in progress.
+ */
+val ListInfo.isSyncing: Boolean
+    get() = state == ListState.FETCHING_FIRST_PAGE || state == ListState.FETCHING_NEXT_PAGE
+
 /**
  * Create an observable metadata collection that notifies observers when data changes.
  *
@@ -69,7 +86,7 @@ class ObservableMetadataCollection(
     private val collection: PostMetadataCollectionWithEditContext
 ) : AutoCloseable {
     private val dataObservers = CopyOnWriteArrayList<() -> Unit>()
-    private val stateObservers = CopyOnWriteArrayList<() -> Unit>()
+    private val listInfoObservers = CopyOnWriteArrayList<() -> Unit>()
 
     /**
      * Add an observer for data changes (list contents changed).
@@ -85,30 +102,28 @@ class ObservableMetadataCollection(
     }
 
     /**
-     * Add an observer for state changes (sync status changed).
+     * Add an observer for list info changes (pagination or sync state changed).
      *
-     * State observers are notified when the sync state changes:
-     * - Idle -> FetchingFirstPage (refresh started)
-     * - Idle -> FetchingNextPage (load more started)
-     * - Fetching* -> Idle (sync completed)
-     * - Fetching* -> Error (sync failed)
+     * ListInfo observers are notified when:
+     * - Pagination info changes (current page, total pages updated after fetch)
+     * - Sync state changes (Idle -> FetchingFirstPage, etc.)
      *
-     * Use this for updating loading indicators in the UI.
+     * Use this for updating pagination display and loading indicators in the UI.
      */
-    fun addStateObserver(observer: () -> Unit) {
-        stateObservers.add(observer)
+    fun addListInfoObserver(observer: () -> Unit) {
+        listInfoObservers.add(observer)
     }
 
     /**
-     * Add an observer for both data and state changes.
+     * Add an observer for both data and list info changes.
      *
      * This is a convenience method that registers the observer for both
-     * data and state updates. Use this when you want to refresh the entire
+     * data and list info updates. Use this when you want to refresh the entire
      * UI on any change.
      */
     fun addObserver(observer: () -> Unit) {
         dataObservers.add(observer)
-        stateObservers.add(observer)
+        listInfoObservers.add(observer)
     }
 
     /**
@@ -119,18 +134,18 @@ class ObservableMetadataCollection(
     }
 
     /**
-     * Remove a state observer.
+     * Remove a list info observer.
      */
-    fun removeStateObserver(observer: () -> Unit) {
-        stateObservers.remove(observer)
+    fun removeListInfoObserver(observer: () -> Unit) {
+        listInfoObservers.remove(observer)
     }
 
     /**
-     * Remove an observer from both data and state lists.
+     * Remove an observer from both data and list info lists.
      */
     fun removeObserver(observer: () -> Unit) {
         dataObservers.remove(observer)
-        stateObservers.remove(observer)
+        listInfoObservers.remove(observer)
     }
 
     /**
@@ -181,49 +196,37 @@ class ObservableMetadataCollection(
     suspend fun loadNextPage(): SyncResult = collection.loadNextPage()
 
     /**
-     * Check if there are more pages to load.
-     */
-    fun hasMorePages(): Boolean = collection.hasMorePages()
-
-    /**
-     * Get the current page number (0 = not loaded yet).
-     */
-    fun currentPage(): UInt = collection.currentPage()
-
-    /**
-     * Get the total number of pages, if known.
-     */
-    fun totalPages(): UInt? = collection.totalPages()
-
-    /**
-     * Get the current sync state for this collection.
+     * Get combined list info (pagination + sync state) in a single query.
+     *
+     * Returns `null` if the list hasn't been created yet.
      *
-     * Returns:
-     * - [ListState.IDLE] - No sync in progress
-     * - [ListState.FETCHING_FIRST_PAGE] - Refresh in progress
-     * - [ListState.FETCHING_NEXT_PAGE] - Load more in progress
-     * - [ListState.ERROR] - Last sync failed
+     * The returned [ListInfo] contains:
+     * - `state`: Current sync state (IDLE, FETCHING_FIRST_PAGE, FETCHING_NEXT_PAGE, ERROR)
+     * - `errorMessage`: Error message if state is ERROR
+     * - `currentPage`: Current page number (0 = not loaded yet)
+     * - `totalPages`: Total pages if known
+     * - `totalItems`: Total items if known
+     * - `perPage`: Items per page setting
      *
-     * Use this with state observers to show loading indicators in the UI.
-     * This is a suspend function that reads from the database on a background thread.
+     * Use [ListInfo.hasMorePages] extension to check if more pages are available.
      */
-    suspend fun syncState(): ListState = collection.syncState()
+    fun listInfo(): ListInfo? = collection.listInfo()
 
     /**
      * Internal method called by DatabaseChangeNotifier when a database update occurs.
      *
      * Checks relevance and notifies appropriate observers:
      * - Data updates -> dataObservers
-     * - State updates -> stateObservers
+     * - List info updates -> listInfoObservers
      */
     internal fun notifyIfRelevant(hook: UpdateHook) {
         val isDataRelevant = collection.isRelevantDataUpdate(hook)
-        val isStateRelevant = collection.isRelevantStateUpdate(hook)
+        val isListInfoRelevant = collection.isRelevantListInfoUpdate(hook)
         if (isDataRelevant) {
             dataObservers.forEach { it() }
         }
-        if (isStateRelevant) {
-            stateObservers.forEach { it() }
+        if (isListInfoRelevant) {
+            listInfoObservers.forEach { it() }
         }
     }
 

native/kotlin/example/composeApp/src/commonMain/kotlin/rs/wordpress/example/shared/ui/postmetadatacollection/PostMetadataCollectionScreen.kt

@@ -400,7 +400,7 @@ fun LoadNextPageCard(
                 ) {
                     Text("Load Next Page")
                 }
-            } else if (state.currentPage > 0u) {
+            } else if (state.currentPage > 0L) {
                 Text(
                     text = "All pages loaded",
                     style = MaterialTheme.typography.caption,

native/kotlin/example/composeApp/src/commonMain/kotlin/rs/wordpress/example/shared/ui/postmetadatacollection/PostMetadataCollectionViewModel.kt

@@ -10,8 +10,11 @@ import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.launch
 import rs.wordpress.cache.kotlin.ObservableMetadataCollection
 import rs.wordpress.cache.kotlin.getObservablePostMetadataCollectionWithEditContext
+import rs.wordpress.cache.kotlin.hasMorePages
+import rs.wordpress.cache.kotlin.isSyncing
 import uniffi.wp_api.PostEndpointType
 import uniffi.wp_api.PostListParams
+import uniffi.wp_mobile.ListInfo
 import uniffi.wp_mobile.PostItemState
 import uniffi.wp_mobile.PostMetadataCollectionItem
 import uniffi.wp_mobile.SyncResult
@@ -23,22 +26,28 @@ import uniffi.wp_mobile_cache.ListState
  */
 data class PostMetadataCollectionState(
     val currentParams: PostListParams,
-    val currentPage: UInt = 0u,
-    val totalPages: UInt? = null,
+    val listInfo: ListInfo? = null,
     val lastSyncResult: SyncResult? = null,
-    val lastError: String? = null,
-    val syncState: ListState = ListState.IDLE
+    val lastError: String? = null
 ) {
     /**
      * Whether a sync operation is in progress.
-     * Derived from syncState - the single source of truth from the database.
+     * Derived from listInfo.state - the single source of truth from the database.
      */
     val isSyncing: Boolean
-        get() = syncState == ListState.FETCHING_FIRST_PAGE ||
-                syncState == ListState.FETCHING_NEXT_PAGE
+        get() = listInfo?.isSyncing ?: false
 
     val hasMorePages: Boolean
-        get() = totalPages?.let { currentPage < it } ?: true
+        get() = listInfo?.hasMorePages ?: true
+
+    val currentPage: Long
+        get() = listInfo?.currentPage ?: 0L
+
+    val totalPages: Long?
+        get() = listInfo?.totalPages
+
+    val syncState: ListState
+        get() = listInfo?.state ?: ListState.IDLE
 
     val filterDisplayName: String
         get() {
@@ -130,29 +139,23 @@ class PostMetadataCollectionViewModel(
         observableCollection?.close()
         createObservableCollection(newParams)
 
-        // Read persisted pagination state from database (sync values)
-        val collection = observableCollection
+        // Read persisted state from database (single query)
         _state.value = PostMetadataCollectionState(
             currentParams = newParams,
-            currentPage = collection?.currentPage() ?: 0u,
-            totalPages = collection?.totalPages(),
+            listInfo = observableCollection?.listInfo(),
             lastSyncResult = null,
-            lastError = null,
-            syncState = ListState.IDLE
+            lastError = null
         )
 
-        // Load items and syncState (async)
-        viewModelScope.launch(Dispatchers.Default) {
-            loadItemsFromCollectionInternal()
-            updateSyncState()
-        }
+        // Load items (async)
+        loadItemsFromCollection()
     }
 
     /**
      * Refresh the collection (fetch page 1, sync missing/stale)
      *
      * Note: syncState is managed by the database and observed via state observer.
-     * We don't manually toggle isSyncing - it's derived from syncState.
+     * We don't manually toggle isSyncing - it's derived from listInfo.state.
      */
     fun refresh() {
         if (_state.value.isSyncing) return
@@ -165,8 +168,7 @@ class PostMetadataCollectionViewModel(
                 val result = collection.refresh()
 
                 _state.value = _state.value.copy(
-                    currentPage = collection.currentPage(),
-                    totalPages = collection.totalPages(),
+                    listInfo = collection.listInfo(),
                     lastSyncResult = result,
                     lastError = null
                 )
@@ -182,14 +184,14 @@ class PostMetadataCollectionViewModel(
      * Load the next page of items
      *
      * Note: syncState is managed by the database and observed via state observer.
-     * We don't manually toggle isSyncing - it's derived from syncState.
+     * We don't manually toggle isSyncing - it's derived from listInfo.state.
      */
     fun loadNextPage() {
         if (_state.value.isSyncing) return
         if (!_state.value.hasMorePages) return
 
         // If no pages have been loaded yet, do a refresh instead
-        if (_state.value.currentPage == 0u) {
+        if (_state.value.currentPage == 0L) {
             refresh()
             return
         }
@@ -202,8 +204,7 @@ class PostMetadataCollectionViewModel(
                 val result = collection.loadNextPage()
 
                 _state.value = _state.value.copy(
-                    currentPage = collection.currentPage(),
-                    totalPages = collection.totalPages(),
+                    listInfo = collection.listInfo(),
                     lastSyncResult = result,
                     lastError = null
                 )
@@ -223,29 +224,26 @@ class PostMetadataCollectionViewModel(
         )
 
         // Data observer: refresh list contents when data changes
-        // Note: Must dispatch to coroutine since loadItems() is a suspend function
         observable.addDataObserver {
             viewModelScope.launch(Dispatchers.Default) {
                 loadItemsFromCollectionInternal()
             }
         }
 
-        // State observer: update sync state indicator when state changes
-        // Note: Must dispatch to coroutine since syncState() is a suspend function
-        observable.addStateObserver {
+        // ListInfo observer: update listInfo when pagination or sync state changes
+        observable.addListInfoObserver {
             viewModelScope.launch(Dispatchers.Default) {
-                updateSyncState()
+                updateListInfo()
             }
         }
 
         observableCollection = observable
     }
 
-    private suspend fun updateSyncState() {
-        val collection = observableCollection ?: return
-        val newSyncState = collection.syncState()
-        println("[ViewModel] updateSyncState: new state = $newSyncState")
-        _state.value = _state.value.copy(syncState = newSyncState)
+    private fun updateListInfo() {
+        val newListInfo = observableCollection?.listInfo()
+        println("[ViewModel] updateListInfo: new state = ${newListInfo?.state}")
+        _state.value = _state.value.copy(listInfo = newListInfo)
     }
 
     private suspend fun loadItemsFromCollectionInternal() {

wp_mobile/src/collection/post_metadata_collection.rs

@@ -9,7 +9,8 @@ use crate::{
     collection::{CollectionError, FetchError},
     service::posts::PostService,
     sync::{
-        EntityState, MetadataCollection, PersistentPostMetadataFetcherWithEditContext, SyncResult,
+        EntityState, ListInfo, MetadataCollection, PersistentPostMetadataFetcherWithEditContext,
+        SyncResult,
     },
 };
 
@@ -191,6 +192,15 @@ impl PostMetadataCollectionWithEditContext {
         self.collection.load_next_page().await
     }
 
+    /// Get combined list info (pagination + sync state) in a single query.
+    ///
+    /// Returns `None` if the list hasn't been created yet.
+    /// Use this instead of calling `current_page()`, `total_pages()`, `sync_state()`
+    /// separately to avoid multiple database queries.
+    pub fn list_info(&self) -> Option<ListInfo> {
+        self.collection.list_info()
+    }
+
     /// Check if there are more pages to load.
     pub fn has_more_pages(&self) -> bool {
         self.collection.has_more_pages()
@@ -244,14 +254,15 @@ impl PostMetadataCollectionWithEditContext {
         self.collection.is_relevant_data_update(hook)
     }
 
-    /// Check if a database update affects this collection's sync state.
+    /// Check if a database update affects this collection's list info (pagination + state).
     ///
-    /// Returns `true` if the update is to the ListMetadataState table
-    /// for this collection's specific list.
+    /// Returns `true` if the update is to:
+    /// - `ListMetadata` table (pagination info changed)
+    /// - `ListMetadataState` table (sync state changed)
     ///
-    /// Use this for state observers that should update loading indicators.
-    pub fn is_relevant_state_update(&self, hook: &UpdateHook) -> bool {
-        self.collection.is_relevant_state_update(hook)
+    /// Use this for listInfo observers that should update pagination display and loading indicators.
+    pub fn is_relevant_list_info_update(&self, hook: &UpdateHook) -> bool {
+        self.collection.is_relevant_list_info_update(hook)
     }
 
     /// Get the API parameters for this collection.

wp_mobile/src/sync/list_metadata_reader.rs

@@ -4,7 +4,7 @@ use wp_mobile_cache::list_metadata::ListState;
 /// Combined list information: pagination + sync state.
 ///
 /// Returned by a single JOIN query on `list_metadata` + `list_metadata_state` tables.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq, uniffi::Record)]
 pub struct ListInfo {
     /// Current sync state (Idle, FetchingFirstPage, FetchingNextPage, Error)
     pub state: ListState,