fix(desktop): audit fixes for deck layout

Critical:
- GlobalFeed now renders global feed (was identical to HomeFeed)
- DeckState uses atomic _columns.update{} instead of non-atomic .value=
- lastKnownWidth marked @Volatile for thread safety

Medium:
- save() debounced 500ms via coroutine (was sync disk I/O per drag frame)
- Width redistribution fills gaps after clamping on column remove
- Hashtag column pre-fills search query
- ColumnNavigationState.stack exposed as StateFlow not MutableStateFlow
- Settings column deduped (focuses existing instead of adding duplicate)
- Exceptions logged in save/load instead of silently swallowed

Low:
- Thread column icon fixed (was Home, now Article)
- Drag divider hit target widened to 12dp (visual stays 4dp)
- Horizontal scroll added for column overflow
- Auto-fit columns on first composition / window resize
- Column shortcuts limited to actual column count
- Deterministic default column IDs
- Overlay fallback shows message instead of blank

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/Main.kt

@@ -141,7 +141,8 @@ fun main() =
             )
         var showComposeDialog by remember { mutableStateOf(false) }
         var replyToNote by remember { mutableStateOf<com.vitorpamplona.quartz.nip01Core.core.Event?>(null) }
-        val deckState = remember { DeckState().also { it.load() } }
+        val deckScope = rememberCoroutineScope()
+        val deckState = remember { DeckState(deckScope).also { it.load() } }
         var showAddColumnDialog by remember { mutableStateOf(false) }
         var layoutMode by remember {
             mutableStateOf(
@@ -179,7 +180,13 @@ fun main() =
                             } else {
                                 KeyShortcut(Key.Comma, ctrl = true)
                             },
-                        onClick = { deckState.addColumn(DeckColumnType.Settings) },
+                        onClick = {
+                            if (deckState.hasColumnOfType(DeckColumnType.Settings)) {
+                                deckState.focusExistingColumn(DeckColumnType.Settings)
+                            } else {
+                                deckState.addColumn(DeckColumnType.Settings)
+                            }
+                        },
                     )
                     Separator()
                     Item(
@@ -305,7 +312,8 @@ fun main() =
                                 Key.Eight,
                                 Key.Nine,
                             )
-                        columnKeys.forEachIndexed { i, key ->
+                        val columnCount = deckState.columns.value.size
+                        columnKeys.take(columnCount).forEachIndexed { i, key ->
                             Item(
                                 "Column ${i + 1}",
                                 shortcut =
@@ -617,7 +625,13 @@ fun MainContent(
                 LayoutMode.DECK -> {
                     DeckSidebar(
                         onAddColumn = onShowAddColumnDialog,
-                        onOpenSettings = { deckState.addColumn(DeckColumnType.Settings) },
+                        onOpenSettings = {
+                            if (deckState.hasColumnOfType(DeckColumnType.Settings)) {
+                                deckState.focusExistingColumn(DeckColumnType.Settings)
+                            } else {
+                                deckState.addColumn(DeckColumnType.Settings)
+                            }
+                        },
                     )
 
                     VerticalDivider()

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

@@ -151,6 +151,7 @@ fun FeedScreen(
     account: AccountState.LoggedIn? = null,
     nwcConnection: com.vitorpamplona.quartz.nip47WalletConnect.Nip47WalletConnect.Nip47URINorm? = null,
     subscriptionsCoordinator: DesktopRelaySubscriptionsCoordinator? = null,
+    initialFeedMode: FeedMode? = null,
     onCompose: () -> Unit = {},
     onNavigateToProfile: (String) -> Unit = {},
     onNavigateToThread: (String) -> Unit = {},
@@ -170,7 +171,7 @@ fun FeedScreen(
         }
     val events by eventState.items.collectAsState()
     var replyToEvent by remember { mutableStateOf<Event?>(null) }
-    var feedMode by remember { mutableStateOf(DesktopPreferences.feedMode) }
+    var feedMode by remember { mutableStateOf(initialFeedMode ?: DesktopPreferences.feedMode) }
     var followedUsers by remember { mutableStateOf<Set<String>>(emptySet()) }
     var zapsByEvent by remember { mutableStateOf<Map<String, List<ZapReceipt>>>(emptyMap()) }
     // Track reaction event IDs per target event to deduplicate

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

@@ -78,6 +78,7 @@ fun SearchScreen(
     localCache: DesktopLocalCache,
     relayManager: DesktopRelayConnectionManager,
     subscriptionsCoordinator: DesktopRelaySubscriptionsCoordinator? = null,
+    initialQuery: String = "",
     onNavigateToProfile: (String) -> Unit,
     onNavigateToThread: (String) -> Unit,
     onNavigateToHashtag: (String) -> Unit = {},
@@ -86,6 +87,13 @@ fun SearchScreen(
     val scope = rememberCoroutineScope()
     val searchState = remember { SearchBarState(localCache, scope) }
     val focusRequester = remember { FocusRequester() }
+
+    // Pre-fill initial query (e.g., hashtag column)
+    LaunchedEffect(initialQuery) {
+        if (initialQuery.isNotBlank()) {
+            searchState.updateSearchText(initialQuery)
+        }
+    }
     val relayStatuses by relayManager.relayStatuses.collectAsState()
 
     // Collect state from SearchBarState

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

@@ -133,6 +133,6 @@ fun DeckColumnType.icon(): ImageVector =
         DeckColumnType.Chess -> Icons.Default.Extension
         DeckColumnType.Settings -> Icons.Default.Settings
         is DeckColumnType.Profile -> Icons.Default.Person
-        is DeckColumnType.Thread -> Icons.Default.Home
+        is DeckColumnType.Thread -> Icons.AutoMirrored.Filled.Article
         is DeckColumnType.Hashtag -> Icons.Default.Tag
     }

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

@@ -43,6 +43,7 @@ import com.vitorpamplona.amethyst.desktop.chess.ChessScreen
 import com.vitorpamplona.amethyst.desktop.model.DesktopIAccount
 import com.vitorpamplona.amethyst.desktop.network.DesktopRelayConnectionManager
 import com.vitorpamplona.amethyst.desktop.subscriptions.DesktopRelaySubscriptionsCoordinator
+import com.vitorpamplona.amethyst.desktop.subscriptions.FeedMode
 import com.vitorpamplona.amethyst.desktop.ui.BookmarksScreen
 import com.vitorpamplona.amethyst.desktop.ui.FeedScreen
 import com.vitorpamplona.amethyst.desktop.ui.NotificationsScreen
@@ -56,10 +57,11 @@ import com.vitorpamplona.amethyst.desktop.ui.chats.DmSendTracker
 import com.vitorpamplona.quartz.nip47WalletConnect.Nip47WalletConnect.Nip47URINorm
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.asStateFlow
 
 class ColumnNavigationState {
     private val _stack = MutableStateFlow<List<DesktopScreen>>(emptyList())
-    val stack = _stack
+    val stack: kotlinx.coroutines.flow.StateFlow<List<DesktopScreen>> = _stack.asStateFlow()
 
     fun push(screen: DesktopScreen) {
         _stack.value = _stack.value + screen
@@ -180,6 +182,7 @@ internal fun RootContent(
                 account = account,
                 nwcConnection = nwcConnection,
                 subscriptionsCoordinator = subscriptionsCoordinator,
+                initialFeedMode = FeedMode.FOLLOWING,
                 onCompose = onShowComposeDialog,
                 onNavigateToProfile = onNavigateToProfile,
                 onNavigateToThread = onNavigateToThread,
@@ -249,6 +252,7 @@ internal fun RootContent(
                 account = account,
                 nwcConnection = nwcConnection,
                 subscriptionsCoordinator = subscriptionsCoordinator,
+                initialFeedMode = FeedMode.GLOBAL,
                 onCompose = onShowComposeDialog,
                 onNavigateToProfile = onNavigateToProfile,
                 onNavigateToThread = onNavigateToThread,
@@ -320,6 +324,7 @@ internal fun RootContent(
                 localCache = localCache,
                 relayManager = relayManager,
                 subscriptionsCoordinator = subscriptionsCoordinator,
+                initialQuery = "#${columnType.tag}",
                 onNavigateToProfile = onNavigateToProfile,
                 onNavigateToThread = onNavigateToThread,
             )
@@ -374,6 +379,12 @@ internal fun OverlayContent(
             )
         }
 
-        else -> {}
+        else -> {
+            androidx.compose.material3.Text(
+                "Unsupported screen type",
+                style = androidx.compose.material3.MaterialTheme.typography.bodyMedium,
+                color = androidx.compose.material3.MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
     }
 }

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

@@ -21,15 +21,18 @@
 package com.vitorpamplona.amethyst.desktop.ui.deck
 
 import androidx.compose.foundation.gestures.detectDragGestures
+import androidx.compose.foundation.horizontalScroll
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.BoxWithConstraints
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.rememberScrollState
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.VerticalDivider
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
@@ -70,7 +73,22 @@ fun DeckLayout(
         val availableWidthDp = with(density) { constraints.maxWidth.toDp().value }
         deckState.setAvailableWidth(availableWidthDp)
 
-        Row(modifier = Modifier.fillMaxSize()) {
+        // Auto-fit columns on first composition or when available width changes significantly
+        LaunchedEffect(availableWidthDp, columns.size) {
+            val dividers = (columns.size - 1) * DeckState.DIVIDER_WIDTH
+            val totalColumnWidth = columns.sumOf { it.width.toDouble() }.toFloat()
+            val diff = kotlin.math.abs(totalColumnWidth + dividers - availableWidthDp)
+            if (diff > 20f && columns.isNotEmpty()) {
+                deckState.fitColumnsToWidth(availableWidthDp)
+            }
+        }
+
+        Row(
+            modifier =
+                Modifier
+                    .fillMaxSize()
+                    .horizontalScroll(rememberScrollState()),
+        ) {
             columns.forEachIndexed { index, column ->
                 if (index > 0) {
                     DraggableDivider(
@@ -108,7 +126,7 @@ private fun DraggableDivider(onDrag: (Float) -> Unit) {
     Box(
         modifier =
             Modifier
-                .width(4.dp)
+                .width(12.dp)
                 .fillMaxHeight()
                 .pointerHoverIcon(PointerIcon(Cursor(Cursor.E_RESIZE_CURSOR)))
                 .pointerInput(Unit) {
@@ -117,6 +135,7 @@ private fun DraggableDivider(onDrag: (Float) -> Unit) {
                         onDrag(dragAmount.x / density)
                     }
                 },
+        contentAlignment = androidx.compose.ui.Alignment.Center,
     ) {
         VerticalDivider(
             color = MaterialTheme.colorScheme.outlineVariant,

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

@@ -23,19 +23,29 @@ package com.vitorpamplona.amethyst.desktop.ui.deck
 import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
 import com.fasterxml.jackson.module.kotlin.readValue
 import com.vitorpamplona.amethyst.desktop.DesktopPreferences
+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.flow.update
+import kotlinx.coroutines.launch
 
-class DeckState {
+class DeckState(
+    private val saveScope: CoroutineScope,
+) {
     private val _columns = MutableStateFlow(DEFAULT_COLUMNS)
     val columns: StateFlow<List<DeckColumn>> = _columns.asStateFlow()
 
     private val _focusedColumnIndex = MutableStateFlow(0)
     val focusedColumnIndex: StateFlow<Int> = _focusedColumnIndex.asStateFlow()
 
+    @Volatile
     private var lastKnownWidth: Float = 0f
 
+    private var saveJob: Job? = null
+
     fun setAvailableWidth(width: Float) {
         lastKnownWidth = width
     }
@@ -45,71 +55,95 @@ class DeckState {
         afterIndex: Int? = null,
     ) {
         val col = DeckColumn(type = type)
-        _columns.value =
+        _columns.update { current ->
-            if (afterIndex != null && afterIndex < _columns.value.size) {
+            if (afterIndex != null && afterIndex < current.size) {
-                _columns.value.toMutableList().apply { add(afterIndex + 1, col) }
+                current.toMutableList().apply { add(afterIndex + 1, col) }
             } else {
-                _columns.value + col
+                current + col
+            }
         }
         // Auto-fit all columns to available width when known
-        if (lastKnownWidth > 0f) {
+        val width = lastKnownWidth
-            fitColumnsToWidth(lastKnownWidth)
+        if (width > 0f) {
+            fitColumnsToWidth(width)
         } else {
-            save()
+            scheduleSave()
         }
     }
 
+    fun hasColumnOfType(type: DeckColumnType): Boolean = _columns.value.any { it.type == type }
+
+    fun focusExistingColumn(type: DeckColumnType) {
+        val idx = _columns.value.indexOfFirst { it.type == type }
+        if (idx >= 0) focusColumn(idx)
+    }
+
     fun removeColumn(id: String) {
-        if (_columns.value.size <= 1) return
+        _columns.update { current ->
-        val removed = _columns.value.find { it.id == id } ?: return
+            if (current.size <= 1) return
-        val remaining = _columns.value.filter { it.id != id }
+            val removed = current.find { it.id == id } ?: return
-        // Redistribute removed column's width evenly across remaining columns
+            val remaining = current.filter { it.id != id }
             val extra = removed.width / remaining.size
-        _columns.value =
+            val result =
                 remaining.map {
                     it.copy(width = (it.width + extra).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH))
                 }
-        if (_focusedColumnIndex.value >= _columns.value.size) {
+            // Fix gaps: if total is less than available, redistribute remainder
-            _focusedColumnIndex.value = _columns.value.size - 1
+            val width = lastKnownWidth
+            if (width > 0f) {
+                val dividers = (result.size - 1) * DIVIDER_WIDTH
+                val totalUsed = result.sumOf { it.width.toDouble() }.toFloat()
+                val deficit = width - dividers - totalUsed
+                if (deficit > 1f) {
+                    val perColumn = deficit / result.size
+                    return@update result.map {
+                        it.copy(width = (it.width + perColumn).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH))
                     }
-        save()
+                }
+            }
+            result
+        }
+        _focusedColumnIndex.update { idx ->
+            idx.coerceAtMost(_columns.value.size - 1)
+        }
+        scheduleSave()
     }
 
     fun moveColumn(
         fromIndex: Int,
         toIndex: Int,
     ) {
-        val list = _columns.value.toMutableList()
+        _columns.update { current ->
-        if (fromIndex !in list.indices || toIndex !in list.indices) return
+            if (fromIndex !in current.indices || toIndex !in current.indices) return
-        val item = list.removeAt(fromIndex)
+            current.toMutableList().apply {
-        list.add(toIndex, item)
+                val item = removeAt(fromIndex)
-        _columns.value = list
+                add(toIndex, item)
-        save()
+            }
+        }
+        scheduleSave()
     }
 
     fun updateColumnWidth(
         id: String,
         width: Float,
     ) {
-        _columns.value =
+        _columns.update { current ->
-            _columns.value.map {
+            current.map {
                 if (it.id == id) it.copy(width = width.coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)) else it
             }
-        save()
+        }
+        scheduleSave()
     }
 
     fun expandColumn(
         id: String,
         availableWidth: Float,
     ) {
-        val cols = _columns.value
+        _columns.update { cols ->
-        val target = cols.find { it.id == id } ?: return
+            if (cols.find { it.id == id } == null) return
-        val others = cols.filter { it.id != id }
+            val othersMin = (cols.size - 1) * MIN_COLUMN_WIDTH
-        // Shrink others to minimum, give the rest to the target
-        val othersMin = others.size * MIN_COLUMN_WIDTH
             val dividerWidth = (cols.size - 1) * DIVIDER_WIDTH
             val maxForTarget = (availableWidth - othersMin - dividerWidth).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)
-        _columns.value =
             cols.map {
                 if (it.id == id) {
                     it.copy(width = maxForTarget)
@@ -117,7 +151,8 @@ class DeckState {
                     it.copy(width = MIN_COLUMN_WIDTH)
                 }
             }
-        save()
+        }
+        scheduleSave()
     }
 
     fun resizePair(
@@ -126,16 +161,14 @@ class DeckState {
         delta: Float,
         availableWidth: Float,
     ) {
-        val cols = _columns.value
+        _columns.update { cols ->
             val left = cols.find { it.id == leftId } ?: return
             val right = cols.find { it.id == rightId } ?: return
-        // Compute max total allowed (available minus other columns and dividers)
             val otherWidth = cols.filter { it.id != leftId && it.id != rightId }.sumOf { it.width.toDouble() }.toFloat()
             val dividerWidth = (cols.size - 1) * DIVIDER_WIDTH
             val maxPairWidth = availableWidth - otherWidth - dividerWidth
             var newLeft = (left.width + delta).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)
             var newRight = (right.width - delta).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)
-        // Ensure pair doesn't exceed available space
             if (newLeft + newRight > maxPairWidth) {
                 if (delta > 0) {
                     newLeft = (maxPairWidth - newRight).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)
@@ -143,7 +176,6 @@ class DeckState {
                     newRight = (maxPairWidth - newLeft).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)
                 }
             }
-        _columns.value =
             cols.map {
                 when (it.id) {
                     leftId -> it.copy(width = newLeft)
@@ -151,17 +183,19 @@ class DeckState {
                     else -> it
                 }
             }
-        save()
+        }
+        scheduleSave()
     }
 
     fun fitColumnsToWidth(availableWidth: Float) {
-        val cols = _columns.value
+        _columns.update { cols ->
             if (cols.isEmpty()) return
             val dividers = (cols.size - 1) * DIVIDER_WIDTH
             val usable = availableWidth - dividers
             val perColumn = (usable / cols.size).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)
-        _columns.value = cols.map { it.copy(width = perColumn) }
+            cols.map { it.copy(width = perColumn) }
-        save()
+        }
+        scheduleSave()
     }
 
     fun focusColumn(index: Int) {
@@ -170,6 +204,15 @@ class DeckState {
         }
     }
 
+    private fun scheduleSave() {
+        saveJob?.cancel()
+        saveJob =
+            saveScope.launch {
+                delay(SAVE_DEBOUNCE_MS)
+                save()
+            }
+    }
+
     fun save() {
         try {
             val data =
@@ -188,7 +231,8 @@ class DeckState {
                     )
                 }
             DesktopPreferences.deckColumns = mapper.writeValueAsString(data)
-        } catch (_: Exception) {
+        } catch (e: Exception) {
+            println("DeckState: failed to save columns: ${e.message}")
         }
     }
 
@@ -207,20 +251,22 @@ class DeckState {
             if (loaded.isNotEmpty()) {
                 _columns.value = loaded
             }
-        } catch (_: Exception) {
+        } catch (e: Exception) {
+            println("DeckState: failed to load columns: ${e.message}")
         }
     }
 
     companion object {
         const val MIN_COLUMN_WIDTH = 300f
         const val MAX_COLUMN_WIDTH = 800f
-        const val DIVIDER_WIDTH = 4f
+        const val DIVIDER_WIDTH = 12f
+        private const val SAVE_DEBOUNCE_MS = 500L
 
         val DEFAULT_COLUMNS =
             listOf(
-                DeckColumn(type = DeckColumnType.HomeFeed),
+                DeckColumn(id = "default-home", type = DeckColumnType.HomeFeed),
-                DeckColumn(type = DeckColumnType.Notifications),
+                DeckColumn(id = "default-notifications", type = DeckColumnType.Notifications),
-                DeckColumn(type = DeckColumnType.Messages),
+                DeckColumn(id = "default-messages", type = DeckColumnType.Messages),
             )
 
         private val mapper = jacksonObjectMapper()