update desktop with refactored classes

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/User.kt

@@ -42,7 +42,6 @@ import com.vitorpamplona.quartz.nip65RelayList.AdvertisedRelayListEvent
 import com.vitorpamplona.quartz.utils.DualCase
 import com.vitorpamplona.quartz.utils.Hex
 import com.vitorpamplona.quartz.utils.containsAny
-import kotlinx.coroutines.flow.MutableStateFlow
 import java.math.BigDecimal
 
 interface UserDependencies
@@ -326,23 +325,9 @@ data class RelayInfo(
     var counter: Long,
 )
 
-@Stable
+// Re-export from commons.state for backwards compatibility
-class UserBundledRefresherFlow(
+typealias UserBundledRefresherFlow = com.vitorpamplona.amethyst.commons.state.UserMetadataState
-    val user: User,
+typealias UserState = com.vitorpamplona.amethyst.commons.state.UserState
-) {
-    val stateFlow = MutableStateFlow(UserState(user))
-
-    fun invalidateData() {
-        stateFlow.tryEmit(UserState(user))
-    }
-
-    fun hasObservers() = stateFlow.subscriptionCount.value > 0
-}
-
-@Immutable
-class UserState(
-    val user: User,
-)
 
 fun Set<User>.toHexSet() = mapTo(LinkedHashSet(size)) { it.pubkeyHex }
 

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/state/EventCollectionState.kt

@@ -0,0 +1,232 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.state
+
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+
+/**
+ * Generic event collection state with deduplication, batching, sorting, and size limits.
+ *
+ * Provides efficient management of event/item collections with:
+ * - Automatic deduplication by ID
+ * - Batched updates (250ms default) to reduce recomposition
+ * - Optional sorting via comparator
+ * - Automatic trimming to max size
+ * - Thread-safe operations
+ *
+ * @param T The type of items to collect (must have a unique ID)
+ * @param getId Function to extract unique ID from an item
+ * @param sortComparator Optional comparator for sorting items (null = prepend newest first)
+ * @param maxSize Maximum number of items to keep (older items trimmed)
+ * @param batchDelayMs Delay in milliseconds before flushing batched updates (default 250ms)
+ * @param scope CoroutineScope for batching jobs
+ *
+ * Usage example:
+ * ```
+ * val feedState = EventCollectionState<Event>(
+ *     getId = { it.id },
+ *     sortComparator = compareByDescending { it.createdAt },
+ *     maxSize = 200,
+ *     scope = viewModelScope
+ * )
+ *
+ * // Add items (batched automatically)
+ * feedState.addItem(event)
+ * feedState.addItems(eventList)
+ *
+ * // Observe
+ * val items by feedState.items.collectAsState()
+ * ```
+ */
+class EventCollectionState<T : Any>(
+    private val getId: (T) -> String,
+    private val sortComparator: Comparator<T>? = null,
+    private val maxSize: Int = 200,
+    private val batchDelayMs: Long = 250,
+    private val scope: CoroutineScope,
+) {
+    private val _items = MutableStateFlow<List<T>>(emptyList())
+    val items: StateFlow<List<T>> = _items.asStateFlow()
+
+    private val seenIds = mutableSetOf<String>()
+    private val pendingItems = mutableListOf<T>()
+    private val mutex = Mutex()
+    private var batchJob: Job? = null
+
+    /**
+     * Add a single item to the collection.
+     * Updates are batched and applied after batchDelayMs.
+     *
+     * @param item The item to add
+     */
+    fun addItem(item: T) {
+        scope.launch {
+            mutex.withLock {
+                val itemId = getId(item)
+                if (itemId !in seenIds) {
+                    pendingItems.add(item)
+                    scheduleBatchUpdate()
+                }
+            }
+        }
+    }
+
+    /**
+     * Add multiple items to the collection.
+     * Updates are batched and applied after batchDelayMs.
+     *
+     * @param items The items to add
+     */
+    fun addItems(items: List<T>) {
+        scope.launch {
+            mutex.withLock {
+                val newItems = items.filter { getId(it) !in seenIds }
+                if (newItems.isNotEmpty()) {
+                    pendingItems.addAll(newItems)
+                    scheduleBatchUpdate()
+                }
+            }
+        }
+    }
+
+    /**
+     * Remove an item by ID.
+     *
+     * @param id The ID of the item to remove
+     */
+    fun removeItem(id: String) {
+        scope.launch {
+            mutex.withLock {
+                seenIds.remove(id)
+                _items.value = _items.value.filter { getId(it) != id }
+            }
+        }
+    }
+
+    /**
+     * Remove multiple items by ID.
+     *
+     * @param ids The IDs of items to remove
+     */
+    fun removeItems(ids: Set<String>) {
+        scope.launch {
+            mutex.withLock {
+                seenIds.removeAll(ids)
+                _items.value = _items.value.filter { getId(it) !in ids }
+            }
+        }
+    }
+
+    /**
+     * Clear all items from the collection.
+     */
+    fun clear() {
+        scope.launch {
+            mutex.withLock {
+                seenIds.clear()
+                pendingItems.clear()
+                _items.value = emptyList()
+                batchJob?.cancel()
+                batchJob = null
+            }
+        }
+    }
+
+    /**
+     * Get current item count.
+     */
+    val size: Int
+        get() = _items.value.size
+
+    /**
+     * Check if collection is empty.
+     */
+    val isEmpty: Boolean
+        get() = _items.value.isEmpty()
+
+    /**
+     * Schedules a batched update if not already scheduled.
+     * Cancels existing batch job and starts a new one.
+     */
+    private fun scheduleBatchUpdate() {
+        batchJob?.cancel()
+        batchJob =
+            scope.launch {
+                delay(batchDelayMs)
+                applyBatchUpdate()
+            }
+    }
+
+    /**
+     * Applies pending items to the collection.
+     * Merges with existing items, sorts if comparator provided, and trims to maxSize.
+     */
+    private suspend fun applyBatchUpdate() {
+        mutex.withLock {
+            if (pendingItems.isEmpty()) return
+
+            // Add pending IDs to seenIds
+            pendingItems.forEach { seenIds.add(getId(it)) }
+
+            // Merge with existing items
+            val merged = _items.value + pendingItems
+
+            // Sort if comparator provided, otherwise keep newest first (pending items already at end)
+            val sorted =
+                if (sortComparator != null) {
+                    merged.sortedWith(sortComparator)
+                } else {
+                    // Reverse so newest (pending) items come first
+                    (pendingItems.reversed() + _items.value).distinctBy { getId(it) }
+                }
+
+            // Trim to maxSize and update seenIds
+            val trimmed =
+                if (sorted.size > maxSize) {
+                    val kept = sorted.take(maxSize)
+                    val removed = sorted.drop(maxSize)
+                    removed.forEach { seenIds.remove(getId(it)) }
+                    kept
+                } else {
+                    sorted
+                }
+
+            _items.value = trimmed
+            pendingItems.clear()
+        }
+    }
+
+    /**
+     * Force flush pending items immediately without waiting for batch delay.
+     */
+    suspend fun flush() {
+        batchJob?.cancel()
+        applyBatchUpdate()
+    }
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/state/FollowState.kt

@@ -0,0 +1,163 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.state
+
+import androidx.compose.runtime.Immutable
+import androidx.compose.runtime.Stable
+import com.vitorpamplona.amethyst.commons.actions.FollowAction
+import com.vitorpamplona.quartz.nip02FollowList.ContactListEvent
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+/**
+ * Represents the current follow relationship status.
+ *
+ * @property isFollowing Whether the target user is currently followed
+ * @property contactList The current ContactListEvent (NIP-02 kind 3)
+ */
+@Immutable
+data class FollowStatus(
+    val isFollowing: Boolean,
+    val contactList: ContactListEvent?,
+)
+
+/**
+ * Reactive state for tracking follow/unfollow status and actions.
+ *
+ * Combines current follow status with action state (loading, success, error)
+ * using LoadingState pattern. Delegates business logic to FollowAction.
+ *
+ * Usage:
+ * ```
+ * val followState = FollowState(myPubKeyHex)
+ *
+ * // Update when contact list arrives from relay
+ * followState.updateContactList(contactListEvent, targetPubKeyHex)
+ *
+ * // Follow action
+ * followState.setFollowLoading()
+ * try {
+ *     val updated = FollowAction.follow(targetPubKeyHex, signer, contactList)
+ *     relayManager.broadcast(updated)
+ *     followState.setFollowSuccess(updated, targetPubKeyHex)
+ * } catch (e: Exception) {
+ *     followState.setFollowError(e.message ?: "Follow failed")
+ * }
+ *
+ * // Observe in UI
+ * when (val state = followState.state.collectAsState().value) {
+ *     is LoadingState.Idle -> { /* Not loaded yet */ }
+ *     is LoadingState.Loading -> CircularProgressIndicator()
+ *     is LoadingState.Success -> {
+ *         val status = state.data
+ *         if (status.isFollowing) UnfollowButton() else FollowButton()
+ *     }
+ *     is LoadingState.Error -> ErrorMessage(state.message)
+ * }
+ * ```
+ *
+ * @property myPubKeyHex The current user's public key hex (for context)
+ */
+@Stable
+class FollowState(
+    private val myPubKeyHex: String,
+) {
+    private val _state = MutableStateFlow<LoadingState<FollowStatus>>(LoadingState.Idle)
+    val state: StateFlow<LoadingState<FollowStatus>> = _state.asStateFlow()
+
+    /**
+     * Updates the follow status based on a ContactListEvent.
+     *
+     * Checks if targetPubKeyHex is in the contact list's p-tags.
+     *
+     * @param event The ContactListEvent (NIP-02 kind 3)
+     * @param targetPubKeyHex The public key of the user to check
+     */
+    fun updateContactList(
+        event: ContactListEvent,
+        targetPubKeyHex: String,
+    ) {
+        val isFollowing = FollowAction.isFollowing(targetPubKeyHex, event)
+        _state.value = LoadingState.Success(FollowStatus(isFollowing, event))
+    }
+
+    /**
+     * Sets the state to Loading (follow/unfollow action in progress).
+     *
+     * Call this before initiating a follow/unfollow action.
+     */
+    fun setFollowLoading() {
+        _state.value = LoadingState.Loading
+    }
+
+    /**
+     * Sets the state to Success with updated follow status.
+     *
+     * Call this after successfully broadcasting a follow/unfollow event.
+     *
+     * @param newContactList The updated ContactListEvent
+     * @param targetPubKeyHex The public key of the user that was followed/unfollowed
+     */
+    fun setFollowSuccess(
+        newContactList: ContactListEvent,
+        targetPubKeyHex: String,
+    ) {
+        val isFollowing = FollowAction.isFollowing(targetPubKeyHex, newContactList)
+        _state.value = LoadingState.Success(FollowStatus(isFollowing, newContactList))
+    }
+
+    /**
+     * Sets the state to Error.
+     *
+     * Call this if follow/unfollow action fails.
+     *
+     * @param message The error message
+     * @param throwable Optional throwable for debugging
+     */
+    fun setFollowError(
+        message: String,
+        throwable: Throwable? = null,
+    ) {
+        _state.value = LoadingState.Error(message, throwable)
+    }
+
+    /**
+     * Gets the current follow status, if loaded.
+     *
+     * @return FollowStatus if state is Success, null otherwise
+     */
+    fun currentStatusOrNull(): FollowStatus? = state.value.dataOrNull()
+
+    /**
+     * Gets the current ContactListEvent, if loaded.
+     *
+     * @return ContactListEvent if state is Success, null otherwise
+     */
+    fun currentContactListOrNull(): ContactListEvent? = currentStatusOrNull()?.contactList
+
+    /**
+     * Checks if currently following, if loaded.
+     *
+     * @return true if following, false if not following or not loaded
+     */
+    fun isFollowing(): Boolean = currentStatusOrNull()?.isFollowing ?: false
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/state/LoadingState.kt

@@ -0,0 +1,109 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.state
+
+/**
+ * Generic loading state representation for async operations.
+ *
+ * Provides type-safe state management for loading, success, error, and empty states.
+ * Eliminates the need for multiple boolean flags (isLoading, hasError, etc.).
+ *
+ * @param T The type of data when successfully loaded
+ *
+ * Usage example:
+ * ```
+ * val feedState: StateFlow<LoadingState<List<Event>>> = ...
+ *
+ * when (val state = feedState.collectAsState().value) {
+ *     is LoadingState.Idle -> { /* Not started yet */ }
+ *     is LoadingState.Loading -> CircularProgressIndicator()
+ *     is LoadingState.Success -> LazyColumn { items(state.data) { ... } }
+ *     is LoadingState.Error -> ErrorMessage(state.message)
+ *     is LoadingState.Empty -> EmptyPlaceholder()
+ * }
+ * ```
+ */
+sealed class LoadingState<out T> {
+    /**
+     * Initial state - operation has not started yet.
+     * Useful for actions (like follow/unfollow) that haven't been triggered.
+     */
+    object Idle : LoadingState<Nothing>()
+
+    /**
+     * Operation is in progress.
+     */
+    object Loading : LoadingState<Nothing>()
+
+    /**
+     * Operation completed successfully with data.
+     *
+     * @param data The loaded data
+     */
+    data class Success<T>(
+        val data: T,
+    ) : LoadingState<T>()
+
+    /**
+     * Operation failed with an error.
+     *
+     * @param message Human-readable error message
+     * @param throwable Optional exception for debugging/logging
+     */
+    data class Error(
+        val message: String,
+        val throwable: Throwable? = null,
+    ) : LoadingState<Nothing>()
+
+    /**
+     * Operation completed successfully but returned no data.
+     * Useful for feeds/lists that have no items.
+     */
+    object Empty : LoadingState<Nothing>()
+
+    /**
+     * Returns true if this state represents a successful load (Success or Empty).
+     */
+    val isSuccessful: Boolean
+        get() = this is Success || this is Empty
+
+    /**
+     * Returns true if this state represents a failure.
+     */
+    val isError: Boolean
+        get() = this is Error
+
+    /**
+     * Returns true if this state is currently loading.
+     */
+    val isLoading: Boolean
+        get() = this is Loading
+
+    /**
+     * Returns the data if this is a Success state, null otherwise.
+     */
+    fun dataOrNull(): T? = if (this is Success) data else null
+
+    /**
+     * Returns the error message if this is an Error state, null otherwise.
+     */
+    fun errorOrNull(): String? = if (this is Error) message else null
+}

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/state/UserMetadataState.kt

@@ -0,0 +1,57 @@
+/**
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.state
+
+import androidx.compose.runtime.Immutable
+import androidx.compose.runtime.Stable
+import com.vitorpamplona.amethyst.commons.model.User
+import kotlinx.coroutines.flow.MutableStateFlow
+
+/**
+ * Reactive state wrapper for User metadata.
+ *
+ * Provides a StateFlow that emits UserState when user metadata changes.
+ * Used by both Android ViewModels and Desktop composables for reactive UI updates.
+ *
+ * Android pattern: UserBundledRefresherFlow (typealias for backwards compatibility)
+ */
+@Stable
+class UserMetadataState(
+    val user: User,
+) {
+    val stateFlow = MutableStateFlow(UserState(user))
+
+    fun invalidateData() {
+        stateFlow.tryEmit(UserState(user))
+    }
+
+    fun hasObservers() = stateFlow.subscriptionCount.value > 0
+}
+
+/**
+ * Immutable snapshot of User state.
+ *
+ * Emitted by UserMetadataState.stateFlow to trigger recomposition.
+ */
+@Immutable
+class UserState(
+    val user: User,
+)

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/FeedScreen.kt

@@ -45,14 +45,15 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import com.vitorpamplona.amethyst.commons.account.AccountState
+import com.vitorpamplona.amethyst.commons.state.EventCollectionState
 import com.vitorpamplona.amethyst.commons.ui.components.LoadingState
 import com.vitorpamplona.amethyst.commons.ui.note.NoteCard
 import com.vitorpamplona.amethyst.commons.util.toNoteDisplayData
@@ -108,8 +109,17 @@ fun FeedScreen(
 ) {
     val connectedRelays by relayManager.connectedRelays.collectAsState()
     val relayStatuses by relayManager.relayStatuses.collectAsState()
-    val events = remember { mutableStateListOf<Event>() }
+    val scope = rememberCoroutineScope()
-    val seenIds = remember { mutableSetOf<String>() }
+    val eventState =
+        remember {
+            EventCollectionState<Event>(
+                getId = { it.id },
+                sortComparator = compareByDescending { it.createdAt },
+                maxSize = 200,
+                scope = scope,
+            )
+        }
+    val events by eventState.items.collectAsState()
     var replyToEvent by remember { mutableStateOf<Event?>(null) }
     var feedMode by remember { mutableStateOf(FeedMode.GLOBAL) }
     var followedUsers by remember { mutableStateOf<Set<String>>(emptySet()) }
@@ -162,8 +172,7 @@ fun FeedScreen(
         val configuredRelays = relayStatuses.keys
         if (configuredRelays.isNotEmpty()) {
             // Clear previous events when switching modes
-            events.clear()
+            eventState.clear()
-            seenIds.clear()
 
             val subId = "${feedMode.name.lowercase()}-feed-${System.currentTimeMillis()}"
             val filters =
@@ -203,14 +212,7 @@ fun FeedScreen(
                                 relay: NormalizedRelayUrl,
                                 forFilters: List<Filter>?,
                             ) {
-                                if (event.id !in seenIds) {
+                                eventState.addItem(event)
-                                    seenIds.add(event.id)
-                                    events.add(0, event)
-                                    if (events.size > 200) {
-                                        val removed = events.removeAt(events.size - 1)
-                                        seenIds.remove(removed.id)
-                                    }
-                                }
                             }
 
                             override fun onEose(

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/NotificationsScreen.kt

@@ -42,8 +42,8 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
@@ -51,6 +51,7 @@ import com.vitorpamplona.amethyst.commons.account.AccountState
 import com.vitorpamplona.amethyst.commons.icons.Reply
 import com.vitorpamplona.amethyst.commons.icons.Repost
 import com.vitorpamplona.amethyst.commons.icons.Zap
+import com.vitorpamplona.amethyst.commons.state.EventCollectionState
 import com.vitorpamplona.amethyst.commons.ui.components.LoadingState
 import com.vitorpamplona.amethyst.commons.ui.feed.FeedHeader
 import com.vitorpamplona.amethyst.commons.util.toTimeAgo
@@ -109,8 +110,17 @@ fun NotificationsScreen(
 ) {
     val connectedRelays by relayManager.connectedRelays.collectAsState()
     val relayStatuses by relayManager.relayStatuses.collectAsState()
-    val notifications = remember { mutableStateListOf<NotificationItem>() }
+    val scope = rememberCoroutineScope()
-    val seenIds = remember { mutableSetOf<String>() }
+    val notificationState =
+        remember {
+            EventCollectionState<NotificationItem>(
+                getId = { it.event.id },
+                sortComparator = null, // Prepend new items (no sorting)
+                maxSize = 200,
+                scope = scope,
+            )
+        }
+    val notifications by notificationState.items.collectAsState()
 
     DisposableEffect(relayStatuses, account.pubKeyHex) {
         val configuredRelays = relayStatuses.keys
@@ -150,50 +160,42 @@ fun NotificationsScreen(
                                 return
                             }
 
-                            if (event.id !in seenIds) {
+                            val notification =
-                                seenIds.add(event.id)
+                                when (event) {
-
+                                    is ReactionEvent ->
-                                val notification =
+                                        NotificationItem.Reaction(
-                                    when (event) {
+                                            event = event,
-                                        is ReactionEvent ->
+                                            timestamp = event.createdAt,
-                                            NotificationItem.Reaction(
+                                            content = event.content,
-                                                event = event,
+                                        )
-                                                timestamp = event.createdAt,
+                                    is RepostEvent, is GenericRepostEvent ->
-                                                content = event.content,
+                                        NotificationItem.Repost(
-                                            )
+                                            event = event,
-                                        is RepostEvent, is GenericRepostEvent ->
+                                            timestamp = event.createdAt,
-                                            NotificationItem.Repost(
+                                        )
-                                                event = event,
+                                    is LnZapEvent -> {
-                                                timestamp = event.createdAt,
+                                        // Extract amount from zap (simplified - full parsing in production)
-                                            )
+                                        val amount = event.amount?.toLong()
-                                        is LnZapEvent -> {
+                                        NotificationItem.Zap(
-                                            // Extract amount from zap (simplified - full parsing in production)
+                                            event = event,
-                                            val amount = event.amount?.toLong()
+                                            timestamp = event.createdAt,
-                                            NotificationItem.Zap(
+                                            amount = amount,
-                                                event = event,
+                                        )
-                                                timestamp = event.createdAt,
-                                                amount = amount,
-                                            )
-                                        }
-                                        is TextNoteEvent -> {
-                                            // Check if it's a reply (has e-tag) or mention
-                                            val eTags = event.tags.filter { it.size > 1 && it[0] == "e" }
-                                            val isReply = eTags.isNotEmpty()
-                                            if (isReply) {
-                                                NotificationItem.Reply(event, event.createdAt)
-                                            } else {
-                                                NotificationItem.Mention(event, event.createdAt)
-                                            }
-                                        }
-                                        else -> NotificationItem.Mention(event, event.createdAt)
                                     }
-
+                                    is TextNoteEvent -> {
-                                notifications.add(0, notification)
+                                        // Check if it's a reply (has e-tag) or mention
-                                if (notifications.size > 200) {
+                                        val eTags = event.tags.filter { it.size > 1 && it[0] == "e" }
-                                    val removed = notifications.removeAt(notifications.size - 1)
+                                        val isReply = eTags.isNotEmpty()
-                                    seenIds.remove(removed.event.id)
+                                        if (isReply) {
+                                            NotificationItem.Reply(event, event.createdAt)
+                                        } else {
+                                            NotificationItem.Mention(event, event.createdAt)
+                                        }
+                                    }
+                                    else -> NotificationItem.Mention(event, event.createdAt)
                                 }
-                            }
+
+                            notificationState.addItem(notification)
                         }
 
                         override fun onEose(

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/UserProfileScreen.kt

@@ -51,7 +51,6 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
@@ -63,6 +62,8 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
 import com.vitorpamplona.amethyst.commons.account.AccountState
 import com.vitorpamplona.amethyst.commons.actions.FollowAction
+import com.vitorpamplona.amethyst.commons.state.EventCollectionState
+import com.vitorpamplona.amethyst.commons.state.FollowState
 import com.vitorpamplona.amethyst.commons.ui.components.LoadingState
 import com.vitorpamplona.amethyst.desktop.network.DesktopRelayConnectionManager
 import com.vitorpamplona.quartz.nip01Core.core.Event
@@ -70,7 +71,6 @@ import com.vitorpamplona.quartz.nip01Core.core.hexToByteArrayOrNull
 import com.vitorpamplona.quartz.nip01Core.relay.client.reqs.IRequestListener
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
-import com.vitorpamplona.quartz.nip01Core.tags.people.isTaggedUser
 import com.vitorpamplona.quartz.nip02FollowList.ContactListEvent
 import com.vitorpamplona.quartz.nip10Notes.TextNoteEvent
 import com.vitorpamplona.quartz.nip19Bech32.toNpub
@@ -100,19 +100,28 @@ fun UserProfileScreen(
     var followersCount by remember { mutableStateOf(0) }
     var followingCount by remember { mutableStateOf(0) }
 
+    val scope = rememberCoroutineScope()
+
     // User's posts
-    val events = remember { mutableStateListOf<Event>() }
+    val eventState =
-    val seenIds = remember { mutableSetOf<String>() }
+        remember {
+            EventCollectionState<Event>(
+                getId = { it.id },
+                sortComparator = compareByDescending { it.createdAt },
+                maxSize = 200,
+                scope = scope,
+            )
+        }
+    val events by eventState.items.collectAsState()
     var postsLoading by remember { mutableStateOf(true) }
     var postsError by remember { mutableStateOf<String?>(null) }
     var retryTrigger by remember { mutableStateOf(0) }
 
     // Follow state
-    var isFollowing by remember { mutableStateOf(false) }
+    val followState =
-    var currentContactList by remember { mutableStateOf<ContactListEvent?>(null) }
+        remember(account) {
-    var isFollowLoading by remember { mutableStateOf(false) }
+            FollowState(myPubKeyHex = account?.pubKeyHex ?: "")
-    var followError by remember { mutableStateOf<String?>(null) }
+        }
-    val scope = rememberCoroutineScope()
 
     // Load current user's contact list (for follow state)
     DisposableEffect(relayStatuses, account) {
@@ -139,8 +148,7 @@ fun UserProfileScreen(
                             forFilters: List<Filter>?,
                         ) {
                             if (event is ContactListEvent) {
-                                currentContactList = event
+                                followState.updateContactList(event, pubKeyHex)
-                                isFollowing = event.isTaggedUser(pubKeyHex)
                             }
                         }
 
@@ -165,8 +173,7 @@ fun UserProfileScreen(
         if (configuredRelays.isNotEmpty()) {
             postsLoading = true
             postsError = null
-            events.clear()
+            eventState.clear()
-            seenIds.clear()
             // Metadata subscription (kind 0)
             val metadataSubId = "profile-metadata-$pubKeyHex-${System.currentTimeMillis()}"
             relayManager.subscribe(
@@ -227,14 +234,7 @@ fun UserProfileScreen(
                             relay: NormalizedRelayUrl,
                             forFilters: List<Filter>?,
                         ) {
-                            if (event.id !in seenIds) {
+                            eventState.addItem(event)
-                                seenIds.add(event.id)
-                                events.add(0, event)
-                                if (events.size > 100) {
-                                    val removed = events.removeAt(events.size - 1)
-                                    seenIds.remove(removed.id)
-                                }
-                            }
                         }
 
                         override fun onEose(
@@ -292,26 +292,28 @@ fun UserProfileScreen(
                     Button(
                         onClick = {
                             scope.launch {
-                                isFollowLoading = true
+                                followState.setFollowLoading()
-                                followError = null
                                 try {
-                                    if (isFollowing) {
+                                    val currentStatus = followState.currentStatusOrNull()
-                                        unfollowUser(pubKeyHex, account, relayManager, currentContactList)
+                                    val updatedEvent =
-                                        isFollowing = false
+                                        if (currentStatus?.isFollowing == true) {
-                                    } else {
+                                            unfollowUser(pubKeyHex, account, relayManager, currentStatus.contactList)
-                                        followUser(pubKeyHex, account, relayManager, currentContactList)
+                                        } else {
-                                        isFollowing = true
+                                            followUser(pubKeyHex, account, relayManager, currentStatus?.contactList)
-                                    }
+                                        }
+                                    followState.setFollowSuccess(updatedEvent, pubKeyHex)
                                 } catch (e: Exception) {
-                                    followError = e.message ?: "Failed to update follow status"
+                                    followState.setFollowError(e.message ?: "Failed to update follow status", e)
-                                } finally {
-                                    isFollowLoading = false
                                 }
                             }
                         },
-                        enabled = !isFollowLoading,
+                        enabled = followState.state.value !is com.vitorpamplona.amethyst.commons.state.LoadingState.Loading,
                     ) {
-                        if (isFollowLoading) {
+                        val state = followState.state.collectAsState().value
+                        val isFollowing = (state as? com.vitorpamplona.amethyst.commons.state.LoadingState.Success)?.data?.isFollowing ?: false
+                        val isLoading = state is com.vitorpamplona.amethyst.commons.state.LoadingState.Loading
+
+                        if (isLoading) {
                             androidx.compose.material3.CircularProgressIndicator(
                                 modifier = Modifier.size(16.dp),
                                 strokeWidth = 2.dp,
@@ -330,7 +332,12 @@ fun UserProfileScreen(
                         }
                     }
 
-                    followError?.let { error ->
+                    val errorMessage =
+                        followState.state
+                            .collectAsState()
+                            .value
+                            .errorOrNull()
+                    errorMessage?.let { error ->
                         Spacer(Modifier.height(4.dp))
                         Text(
                             error,
@@ -526,7 +533,7 @@ private suspend fun followUser(
     account: AccountState.LoggedIn,
     relayManager: DesktopRelayConnectionManager,
     currentContactList: ContactListEvent?,
-) {
+): ContactListEvent =
     withContext(Dispatchers.IO) {
         println("[UserProfile] Starting followUser: target=${pubKeyHex.take(8)}...")
 
@@ -536,8 +543,9 @@ private suspend fun followUser(
         println("[UserProfile] ContactListEvent created, broadcasting...")
         relayManager.broadcastToAll(updatedEvent)
         println("[UserProfile] Follow broadcast complete")
+
+        updatedEvent
     }
-}
 
 /**
  * Unfollows a user by publishing an updated contact list event without them.
@@ -547,7 +555,7 @@ private suspend fun unfollowUser(
     account: AccountState.LoggedIn,
     relayManager: DesktopRelayConnectionManager,
     currentContactList: ContactListEvent?,
-) {
+): ContactListEvent =
     withContext(Dispatchers.IO) {
         println("[UserProfile] Starting unfollowUser: target=${pubKeyHex.take(8)}...")
 
@@ -560,8 +568,10 @@ private suspend fun unfollowUser(
             println("[UserProfile] ContactListEvent updated, broadcasting...")
             relayManager.broadcastToAll(updatedEvent)
             println("[UserProfile] Unfollow broadcast complete")
+
+            updatedEvent
         } else {
             println("[UserProfile] Error: No contact list to unfollow from")
+            throw IllegalStateException("Cannot unfollow: No contact list available")
         }
     }
-}