feat(desktop): add single-pane/deck toggle with smart column resizing

- Add LayoutMode enum (SINGLE_PANE/DECK) persisted in DesktopPreferences
- SinglePaneLayout: NavigationRail + single content area reusing deck routing
- View menu "Deck Layout" toggle with Cmd+Shift+D shortcut
- Column resize: redistribute width on add/remove, double-click header to expand
- Constrain drag resize to window bounds via BoxWithConstraints
- FlowRow headers in FeedScreen/ReadsScreen to wrap on narrow columns

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

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

@@ -36,6 +36,7 @@ object DesktopPreferences {
     private const val KEY_FEED_MODE = "feed_mode"
     private const val KEY_LAST_SCREEN = "last_screen"
     private const val KEY_DECK_COLUMNS = "deck_columns"
+    private const val KEY_LAYOUT_MODE = "layout_mode"
 
     var feedMode: FeedMode
         get() {
@@ -61,4 +62,10 @@ object DesktopPreferences {
         set(value) {
             prefs.put(KEY_DECK_COLUMNS, value)
         }
+
+    var layoutMode: String
+        get() = prefs.get(KEY_LAYOUT_MODE, "SINGLE_PANE")
+        set(value) {
+            prefs.put(KEY_LAYOUT_MODE, value)
+        }
 }

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

@@ -81,6 +81,7 @@ import com.vitorpamplona.amethyst.desktop.ui.deck.DeckColumnType
 import com.vitorpamplona.amethyst.desktop.ui.deck.DeckLayout
 import com.vitorpamplona.amethyst.desktop.ui.deck.DeckSidebar
 import com.vitorpamplona.amethyst.desktop.ui.deck.DeckState
+import com.vitorpamplona.amethyst.desktop.ui.deck.SinglePaneLayout
 import com.vitorpamplona.amethyst.desktop.ui.profile.ProfileInfoCard
 import com.vitorpamplona.amethyst.desktop.ui.relay.RelayStatusCard
 import com.vitorpamplona.quartz.nip47WalletConnect.Nip47WalletConnect
@@ -92,6 +93,11 @@ import kotlinx.coroutines.launch
 
 private val isMacOS = System.getProperty("os.name").lowercase().contains("mac")
 
+enum class LayoutMode {
+    SINGLE_PANE,
+    DECK,
+}
+
 /**
  * Desktop navigation state — used for in-column navigation (drill-down).
  */
@@ -133,6 +139,15 @@ fun main() =
         var replyToNote by remember { mutableStateOf<com.vitorpamplona.quartz.nip01Core.core.Event?>(null) }
         val deckState = remember { DeckState().also { it.load() } }
         var showAddColumnDialog by remember { mutableStateOf(false) }
+        var layoutMode by remember {
+            mutableStateOf(
+                try {
+                    LayoutMode.valueOf(DesktopPreferences.layoutMode)
+                } catch (e: Exception) {
+                    LayoutMode.SINGLE_PANE
+                },
+            )
+        }
 
         Window(
             onCloseRequest = ::exitApplication,
@@ -198,100 +213,117 @@ fun main() =
                 }
                 Menu("View") {
                     Item(
-                        "Add Column",
+                        if (layoutMode == LayoutMode.DECK) "\u2713 Deck Layout" else "Deck Layout",
                         shortcut =
                             if (isMacOS) {
-                                KeyShortcut(Key.T, meta = true)
+                                KeyShortcut(Key.D, meta = true, shift = true)
                             } else {
-                                KeyShortcut(Key.T, ctrl = true)
+                                KeyShortcut(Key.D, ctrl = true, shift = true)
-                            },
-                        onClick = { showAddColumnDialog = true },
-                    )
-                    Item(
-                        "Close Column",
-                        shortcut =
-                            if (isMacOS) {
-                                KeyShortcut(Key.W, meta = true)
-                            } else {
-                                KeyShortcut(Key.W, ctrl = true)
                             },
                         onClick = {
-                            val cols = deckState.columns.value
+                            layoutMode =
-                            val idx = deckState.focusedColumnIndex.value
+                                if (layoutMode == LayoutMode.DECK) LayoutMode.SINGLE_PANE else LayoutMode.DECK
-                            if (cols.size > 1 && idx in cols.indices) {
+                            DesktopPreferences.layoutMode = layoutMode.name
-                                deckState.removeColumn(cols[idx].id)
-                            }
                         },
                     )
-                    Item(
+                    if (layoutMode == LayoutMode.DECK) {
-                        "Move Column Left",
+                        Separator()
-                        shortcut =
-                            if (isMacOS) {
-                                KeyShortcut(Key.DirectionLeft, meta = true, shift = true)
-                            } else {
-                                KeyShortcut(Key.DirectionLeft, ctrl = true, shift = true)
-                            },
-                        onClick = {
-                            val idx = deckState.focusedColumnIndex.value
-                            if (idx > 0) {
-                                deckState.moveColumn(idx, idx - 1)
-                                deckState.focusColumn(idx - 1)
-                            }
-                        },
-                    )
-                    Item(
-                        "Move Column Right",
-                        shortcut =
-                            if (isMacOS) {
-                                KeyShortcut(Key.DirectionRight, meta = true, shift = true)
-                            } else {
-                                KeyShortcut(Key.DirectionRight, ctrl = true, shift = true)
-                            },
-                        onClick = {
-                            val idx = deckState.focusedColumnIndex.value
-                            val size = deckState.columns.value.size
-                            if (idx < size - 1) {
-                                deckState.moveColumn(idx, idx + 1)
-                                deckState.focusColumn(idx + 1)
-                            }
-                        },
-                    )
-                    Separator()
-                    // Focus column by index (Cmd/Ctrl+1..9)
-                    val columnKeys =
-                        listOf(
-                            Key.One,
-                            Key.Two,
-                            Key.Three,
-                            Key.Four,
-                            Key.Five,
-                            Key.Six,
-                            Key.Seven,
-                            Key.Eight,
-                            Key.Nine,
-                        )
-                    columnKeys.forEachIndexed { i, key ->
                         Item(
-                            "Column ${i + 1}",
+                            "Add Column",
                             shortcut =
                                 if (isMacOS) {
-                                    KeyShortcut(key, meta = true)
+                                    KeyShortcut(Key.T, meta = true)
                                 } else {
-                                    KeyShortcut(key, ctrl = true)
+                                    KeyShortcut(Key.T, ctrl = true)
                                 },
-                            onClick = { deckState.focusColumn(i) },
+                            onClick = { showAddColumnDialog = true },
                         )
-                    }
+                        Item(
-                    Separator()
+                            "Close Column",
-                    Menu("Add Column...") {
+                            shortcut =
-                        Item("Home Feed", onClick = { deckState.addColumn(DeckColumnType.HomeFeed) })
+                                if (isMacOS) {
-                        Item("Notifications", onClick = { deckState.addColumn(DeckColumnType.Notifications) })
+                                    KeyShortcut(Key.W, meta = true)
-                        Item("Messages", onClick = { deckState.addColumn(DeckColumnType.Messages) })
+                                } else {
-                        Item("Search", onClick = { deckState.addColumn(DeckColumnType.Search) })
+                                    KeyShortcut(Key.W, ctrl = true)
-                        Item("Reads", onClick = { deckState.addColumn(DeckColumnType.Reads) })
+                                },
-                        Item("Bookmarks", onClick = { deckState.addColumn(DeckColumnType.Bookmarks) })
+                            onClick = {
-                        Item("Global Feed", onClick = { deckState.addColumn(DeckColumnType.GlobalFeed) })
+                                val cols = deckState.columns.value
-                        Item("Profile", onClick = { deckState.addColumn(DeckColumnType.MyProfile) })
+                                val idx = deckState.focusedColumnIndex.value
+                                if (cols.size > 1 && idx in cols.indices) {
+                                    deckState.removeColumn(cols[idx].id)
+                                }
+                            },
+                        )
+                        Item(
+                            "Move Column Left",
+                            shortcut =
+                                if (isMacOS) {
+                                    KeyShortcut(Key.DirectionLeft, meta = true, shift = true)
+                                } else {
+                                    KeyShortcut(Key.DirectionLeft, ctrl = true, shift = true)
+                                },
+                            onClick = {
+                                val idx = deckState.focusedColumnIndex.value
+                                if (idx > 0) {
+                                    deckState.moveColumn(idx, idx - 1)
+                                    deckState.focusColumn(idx - 1)
+                                }
+                            },
+                        )
+                        Item(
+                            "Move Column Right",
+                            shortcut =
+                                if (isMacOS) {
+                                    KeyShortcut(Key.DirectionRight, meta = true, shift = true)
+                                } else {
+                                    KeyShortcut(Key.DirectionRight, ctrl = true, shift = true)
+                                },
+                            onClick = {
+                                val idx = deckState.focusedColumnIndex.value
+                                val size = deckState.columns.value.size
+                                if (idx < size - 1) {
+                                    deckState.moveColumn(idx, idx + 1)
+                                    deckState.focusColumn(idx + 1)
+                                }
+                            },
+                        )
+                        Separator()
+                        // Focus column by index (Cmd/Ctrl+1..9)
+                        val columnKeys =
+                            listOf(
+                                Key.One,
+                                Key.Two,
+                                Key.Three,
+                                Key.Four,
+                                Key.Five,
+                                Key.Six,
+                                Key.Seven,
+                                Key.Eight,
+                                Key.Nine,
+                            )
+                        columnKeys.forEachIndexed { i, key ->
+                            Item(
+                                "Column ${i + 1}",
+                                shortcut =
+                                    if (isMacOS) {
+                                        KeyShortcut(key, meta = true)
+                                    } else {
+                                        KeyShortcut(key, ctrl = true)
+                                    },
+                                onClick = { deckState.focusColumn(i) },
+                            )
+                        }
+                        Separator()
+                        Menu("Add Column...") {
+                            Item("Home Feed", onClick = { deckState.addColumn(DeckColumnType.HomeFeed) })
+                            Item("Notifications", onClick = { deckState.addColumn(DeckColumnType.Notifications) })
+                            Item("Messages", onClick = { deckState.addColumn(DeckColumnType.Messages) })
+                            Item("Search", onClick = { deckState.addColumn(DeckColumnType.Search) })
+                            Item("Reads", onClick = { deckState.addColumn(DeckColumnType.Reads) })
+                            Item("Bookmarks", onClick = { deckState.addColumn(DeckColumnType.Bookmarks) })
+                            Item("Global Feed", onClick = { deckState.addColumn(DeckColumnType.GlobalFeed) })
+                            Item("Profile", onClick = { deckState.addColumn(DeckColumnType.MyProfile) })
+                        }
                     }
                 }
                 Menu("Help") {
@@ -301,6 +333,7 @@ fun main() =
             }
 
             App(
+                layoutMode = layoutMode,
                 deckState = deckState,
                 showComposeDialog = showComposeDialog,
                 showAddColumnDialog = showAddColumnDialog,
@@ -322,6 +355,7 @@ fun main() =
 
 @Composable
 fun App(
+    layoutMode: LayoutMode,
     deckState: DeckState,
     showComposeDialog: Boolean,
     showAddColumnDialog: Boolean,
@@ -425,6 +459,7 @@ fun App(
                     }
 
                     MainContent(
+                        layoutMode = layoutMode,
                         deckState = deckState,
                         relayManager = relayManager,
                         localCache = localCache,
@@ -466,6 +501,7 @@ fun App(
 
 @Composable
 fun MainContent(
+    layoutMode: LayoutMode,
     deckState: DeckState,
     relayManager: DesktopRelayConnectionManager,
     localCache: DesktopLocalCache,
@@ -497,27 +533,47 @@ fun MainContent(
 
     Box(Modifier.fillMaxSize()) {
         Row(Modifier.fillMaxSize()) {
-            DeckSidebar(
+            when (layoutMode) {
-                onAddColumn = onShowAddColumnDialog,
+                LayoutMode.SINGLE_PANE -> {
-                onOpenSettings = { deckState.addColumn(DeckColumnType.Settings) },
+                    SinglePaneLayout(
-            )
+                        relayManager = relayManager,
+                        localCache = localCache,
+                        accountManager = accountManager,
+                        account = account,
+                        nwcConnection = nwcConnection,
+                        subscriptionsCoordinator = subscriptionsCoordinator,
+                        appScope = appScope,
+                        onShowComposeDialog = onShowComposeDialog,
+                        onShowReplyDialog = onShowReplyDialog,
+                        onZapFeedback = onZapFeedback,
+                        modifier = Modifier.weight(1f),
+                    )
+                }
 
-            VerticalDivider()
+                LayoutMode.DECK -> {
+                    DeckSidebar(
+                        onAddColumn = onShowAddColumnDialog,
+                        onOpenSettings = { deckState.addColumn(DeckColumnType.Settings) },
+                    )
 
-            DeckLayout(
+                    VerticalDivider()
-                deckState = deckState,
+
-                relayManager = relayManager,
+                    DeckLayout(
-                localCache = localCache,
+                        deckState = deckState,
-                accountManager = accountManager,
+                        relayManager = relayManager,
-                account = account,
+                        localCache = localCache,
-                nwcConnection = nwcConnection,
+                        accountManager = accountManager,
-                subscriptionsCoordinator = subscriptionsCoordinator,
+                        account = account,
-                appScope = appScope,
+                        nwcConnection = nwcConnection,
-                onShowComposeDialog = onShowComposeDialog,
+                        subscriptionsCoordinator = subscriptionsCoordinator,
-                onShowReplyDialog = onShowReplyDialog,
+                        appScope = appScope,
-                onZapFeedback = onZapFeedback,
+                        onShowComposeDialog = onShowComposeDialog,
-                modifier = Modifier.weight(1f),
+                        onShowReplyDialog = onShowReplyDialog,
-            )
+                        onZapFeedback = onZapFeedback,
+                        modifier = Modifier.weight(1f),
+                    )
+                }
+            }
         }
 
         // Snackbar for zap feedback

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

@@ -23,6 +23,8 @@ package com.vitorpamplona.amethyst.desktop.ui
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ExperimentalLayoutApi
+import androidx.compose.foundation.layout.FlowRow
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
@@ -475,16 +477,17 @@ fun FeedScreen(
         )
     }
 
+    @OptIn(ExperimentalLayoutApi::class)
     Column(modifier = Modifier.fillMaxSize()) {
-        // Header with compose button
+        // Header with compose button — wraps on narrow columns
-        Row(
+        FlowRow(
             modifier = Modifier.fillMaxWidth().padding(bottom = 16.dp),
             horizontalArrangement = Arrangement.SpaceBetween,
-            verticalAlignment = Alignment.CenterVertically,
+            verticalArrangement = Arrangement.spacedBy(8.dp),
         ) {
             Column {
-                Row(
+                FlowRow(
-                    verticalAlignment = Alignment.CenterVertically,
+                    verticalArrangement = Arrangement.Center,
                     horizontalArrangement = Arrangement.spacedBy(8.dp),
                 ) {
                     Text(

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

@@ -23,6 +23,8 @@ package com.vitorpamplona.amethyst.desktop.ui
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.ExperimentalLayoutApi
+import androidx.compose.foundation.layout.FlowRow
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
@@ -259,16 +261,17 @@ fun ReadsScreen(
         }
     }
 
+    @OptIn(ExperimentalLayoutApi::class)
     Column(modifier = Modifier.fillMaxSize()) {
-        // Header
+        // Header — wraps on narrow columns
-        Row(
+        FlowRow(
             modifier = Modifier.fillMaxWidth().padding(bottom = 16.dp),
             horizontalArrangement = Arrangement.SpaceBetween,
-            verticalAlignment = Alignment.CenterVertically,
+            verticalArrangement = Arrangement.spacedBy(8.dp),
         ) {
             Column {
-                Row(
+                FlowRow(
-                    verticalAlignment = Alignment.CenterVertically,
+                    verticalArrangement = Arrangement.Center,
                     horizontalArrangement = Arrangement.spacedBy(8.dp),
                 ) {
                     Text(

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

@@ -21,6 +21,7 @@
 package com.vitorpamplona.amethyst.desktop.ui.deck
 
 import androidx.compose.foundation.background
+import androidx.compose.foundation.gestures.detectTapGestures
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxWidth
@@ -48,6 +49,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 
@@ -58,6 +60,7 @@ fun ColumnHeader(
     hasBackStack: Boolean,
     onBack: () -> Unit,
     onClose: () -> Unit,
+    onDoubleClick: () -> Unit = {},
     modifier: Modifier = Modifier,
 ) {
     Row(
@@ -66,7 +69,11 @@ fun ColumnHeader(
                 .fillMaxWidth()
                 .height(40.dp)
                 .background(MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.5f))
-                .padding(horizontal = 8.dp),
+                .pointerInput(Unit) {
+                    detectTapGestures(
+                        onDoubleTap = { onDoubleClick() },
+                    )
+                }.padding(horizontal = 8.dp),
         verticalAlignment = Alignment.CenterVertically,
     ) {
         if (hasBackStack) {

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

@@ -80,6 +80,7 @@ fun DeckColumnContainer(
     column: DeckColumn,
     canClose: Boolean,
     onClose: () -> Unit,
+    onDoubleClickHeader: () -> Unit = {},
     relayManager: DesktopRelayConnectionManager,
     localCache: DesktopLocalCache,
     accountManager: AccountManager,
@@ -108,6 +109,7 @@ fun DeckColumnContainer(
             hasBackStack = navStack.isNotEmpty(),
             onBack = { navState.pop() },
             onClose = onClose,
+            onDoubleClick = onDoubleClickHeader,
         )
 
         HorizontalDivider()
@@ -152,7 +154,7 @@ fun DeckColumnContainer(
 }
 
 @Composable
-private fun RootContent(
+internal fun RootContent(
     columnType: DeckColumnType,
     relayManager: DesktopRelayConnectionManager,
     localCache: DesktopLocalCache,
@@ -314,7 +316,7 @@ private fun RootContent(
 }
 
 @Composable
-private fun OverlayContent(
+internal fun OverlayContent(
     screen: DesktopScreen,
     relayManager: DesktopRelayConnectionManager,
     localCache: DesktopLocalCache,

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

@@ -21,13 +21,12 @@
 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
@@ -37,6 +36,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.input.pointer.PointerIcon
 import androidx.compose.ui.input.pointer.pointerHoverIcon
 import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.unit.dp
 import com.vitorpamplona.amethyst.desktop.account.AccountManager
 import com.vitorpamplona.amethyst.desktop.account.AccountState
@@ -64,38 +64,41 @@ fun DeckLayout(
     modifier: Modifier = Modifier,
 ) {
     val columns by deckState.columns.collectAsState()
-    val scrollState = rememberScrollState()
+    val density = LocalDensity.current
 
-    Row(
+    BoxWithConstraints(modifier = modifier.fillMaxSize()) {
-        modifier = modifier.fillMaxSize().horizontalScroll(scrollState),
+        val availableWidthDp = with(density) { constraints.maxWidth.toDp().value }
-    ) {
+        deckState.setAvailableWidth(availableWidthDp)
-        columns.forEachIndexed { index, column ->
+
-            if (index > 0) {
+        Row(modifier = Modifier.fillMaxSize()) {
-                DraggableDivider(
+            columns.forEachIndexed { index, column ->
-                    onDrag = { delta ->
+                if (index > 0) {
-                        val leftCol = columns[index - 1]
+                    DraggableDivider(
-                        val rightCol = columns[index]
+                        onDrag = { delta ->
-                        deckState.updateColumnWidth(leftCol.id, leftCol.width + delta)
+                            val leftCol = columns[index - 1]
-                        deckState.updateColumnWidth(rightCol.id, rightCol.width - delta)
+                            val rightCol = columns[index]
-                    },
+                            deckState.resizePair(leftCol.id, rightCol.id, delta, availableWidthDp)
+                        },
+                    )
+                }
+
+                DeckColumnContainer(
+                    column = column,
+                    canClose = columns.size > 1,
+                    onClose = { deckState.removeColumn(column.id) },
+                    onDoubleClickHeader = { deckState.expandColumn(column.id, availableWidthDp) },
+                    relayManager = relayManager,
+                    localCache = localCache,
+                    accountManager = accountManager,
+                    account = account,
+                    nwcConnection = nwcConnection,
+                    subscriptionsCoordinator = subscriptionsCoordinator,
+                    appScope = appScope,
+                    onShowComposeDialog = onShowComposeDialog,
+                    onShowReplyDialog = onShowReplyDialog,
+                    onZapFeedback = onZapFeedback,
                 )
             }
-
-            DeckColumnContainer(
-                column = column,
-                canClose = columns.size > 1,
-                onClose = { deckState.removeColumn(column.id) },
-                relayManager = relayManager,
-                localCache = localCache,
-                accountManager = accountManager,
-                account = account,
-                nwcConnection = nwcConnection,
-                subscriptionsCoordinator = subscriptionsCoordinator,
-                appScope = appScope,
-                onShowComposeDialog = onShowComposeDialog,
-                onShowReplyDialog = onShowReplyDialog,
-                onZapFeedback = onZapFeedback,
-            )
         }
     }
 }

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

@@ -34,6 +34,12 @@ class DeckState {
     private val _focusedColumnIndex = MutableStateFlow(0)
     val focusedColumnIndex: StateFlow<Int> = _focusedColumnIndex.asStateFlow()
 
+    private var lastKnownWidth: Float = 0f
+
+    fun setAvailableWidth(width: Float) {
+        lastKnownWidth = width
+    }
+
     fun addColumn(
         type: DeckColumnType,
         afterIndex: Int? = null,
@@ -45,12 +51,24 @@ class DeckState {
             } else {
                 _columns.value + col
             }
-        save()
+        // Auto-fit all columns to available width when known
+        if (lastKnownWidth > 0f) {
+            fitColumnsToWidth(lastKnownWidth)
+        } else {
+            save()
+        }
     }
 
     fun removeColumn(id: String) {
         if (_columns.value.size <= 1) return
-        _columns.value = _columns.value.filter { it.id != id }
+        val removed = _columns.value.find { it.id == id } ?: return
+        val remaining = _columns.value.filter { it.id != id }
+        // Redistribute removed column's width evenly across remaining columns
+        val extra = removed.width / remaining.size
+        _columns.value =
+            remaining.map {
+                it.copy(width = (it.width + extra).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH))
+            }
         if (_focusedColumnIndex.value >= _columns.value.size) {
             _focusedColumnIndex.value = _columns.value.size - 1
         }
@@ -80,6 +98,72 @@ class DeckState {
         save()
     }
 
+    fun expandColumn(
+        id: String,
+        availableWidth: Float,
+    ) {
+        val cols = _columns.value
+        val target = cols.find { it.id == id } ?: return
+        val others = cols.filter { it.id != id }
+        // 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)
+                } else {
+                    it.copy(width = MIN_COLUMN_WIDTH)
+                }
+            }
+        save()
+    }
+
+    fun resizePair(
+        leftId: String,
+        rightId: String,
+        delta: Float,
+        availableWidth: Float,
+    ) {
+        val cols = _columns.value
+        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)
+            } else {
+                newRight = (maxPairWidth - newLeft).coerceIn(MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)
+            }
+        }
+        _columns.value =
+            cols.map {
+                when (it.id) {
+                    leftId -> it.copy(width = newLeft)
+                    rightId -> it.copy(width = newRight)
+                    else -> it
+                }
+            }
+        save()
+    }
+
+    fun fitColumnsToWidth(availableWidth: Float) {
+        val cols = _columns.value
+        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) }
+        save()
+    }
+
     fun focusColumn(index: Int) {
         if (index in _columns.value.indices) {
             _focusedColumnIndex.value = index
@@ -130,6 +214,7 @@ class DeckState {
     companion object {
         const val MIN_COLUMN_WIDTH = 300f
         const val MAX_COLUMN_WIDTH = 800f
+        const val DIVIDER_WIDTH = 4f
 
         val DEFAULT_COLUMNS =
             listOf(

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

@@ -0,0 +1,231 @@
+/*
+ * 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.desktop.ui.deck
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material.icons.automirrored.filled.Article
+import androidx.compose.material.icons.filled.Bookmark
+import androidx.compose.material.icons.filled.Email
+import androidx.compose.material.icons.filled.Home
+import androidx.compose.material.icons.filled.Notifications
+import androidx.compose.material.icons.filled.Person
+import androidx.compose.material.icons.filled.Search
+import androidx.compose.material.icons.filled.Settings
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.NavigationRail
+import androidx.compose.material3.NavigationRailItem
+import androidx.compose.material3.Text
+import androidx.compose.material3.VerticalDivider
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.desktop.DesktopScreen
+import com.vitorpamplona.amethyst.desktop.account.AccountManager
+import com.vitorpamplona.amethyst.desktop.account.AccountState
+import com.vitorpamplona.amethyst.desktop.cache.DesktopLocalCache
+import com.vitorpamplona.amethyst.desktop.network.DesktopRelayConnectionManager
+import com.vitorpamplona.amethyst.desktop.subscriptions.DesktopRelaySubscriptionsCoordinator
+import com.vitorpamplona.amethyst.desktop.ui.ZapFeedback
+import com.vitorpamplona.quartz.nip47WalletConnect.Nip47WalletConnect.Nip47URINorm
+import kotlinx.coroutines.CoroutineScope
+
+private data class NavItem(
+    val type: DeckColumnType,
+    val icon: ImageVector,
+    val label: String,
+)
+
+private val navItems =
+    listOf(
+        NavItem(DeckColumnType.HomeFeed, Icons.Default.Home, "Home"),
+        NavItem(DeckColumnType.Reads, Icons.AutoMirrored.Filled.Article, "Reads"),
+        NavItem(DeckColumnType.Search, Icons.Default.Search, "Search"),
+        NavItem(DeckColumnType.Bookmarks, Icons.Default.Bookmark, "Bookmarks"),
+        NavItem(DeckColumnType.Messages, Icons.Default.Email, "Messages"),
+        NavItem(DeckColumnType.Notifications, Icons.Default.Notifications, "Notifications"),
+        NavItem(DeckColumnType.MyProfile, Icons.Default.Person, "Profile"),
+        NavItem(DeckColumnType.Settings, Icons.Default.Settings, "Settings"),
+    )
+
+@Composable
+fun SinglePaneLayout(
+    relayManager: DesktopRelayConnectionManager,
+    localCache: DesktopLocalCache,
+    accountManager: AccountManager,
+    account: AccountState.LoggedIn,
+    nwcConnection: Nip47URINorm?,
+    subscriptionsCoordinator: DesktopRelaySubscriptionsCoordinator,
+    appScope: CoroutineScope,
+    onShowComposeDialog: () -> Unit,
+    onShowReplyDialog: (com.vitorpamplona.quartz.nip01Core.core.Event) -> Unit,
+    onZapFeedback: (ZapFeedback) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    var currentColumnType by remember { mutableStateOf<DeckColumnType>(DeckColumnType.HomeFeed) }
+    val navState = remember { ColumnNavigationState() }
+    val navStack by navState.stack.collectAsState()
+    val currentOverlay = navStack.lastOrNull()
+
+    Row(modifier = modifier.fillMaxSize()) {
+        NavigationRail(
+            modifier = Modifier.width(80.dp).fillMaxHeight(),
+            containerColor = MaterialTheme.colorScheme.surfaceVariant,
+        ) {
+            navItems.forEach { item ->
+                NavigationRailItem(
+                    selected = currentColumnType == item.type && navStack.isEmpty(),
+                    onClick = {
+                        currentColumnType = item.type
+                        navState.clear()
+                    },
+                    icon = {
+                        Icon(
+                            item.icon,
+                            contentDescription = item.label,
+                            modifier = Modifier.size(22.dp),
+                        )
+                    },
+                    label = {
+                        Text(
+                            item.label,
+                            style = MaterialTheme.typography.labelSmall,
+                            maxLines = 1,
+                            overflow = TextOverflow.Ellipsis,
+                        )
+                    },
+                )
+            }
+        }
+
+        VerticalDivider()
+
+        Column(modifier = Modifier.weight(1f).fillMaxHeight()) {
+            // Show header with back button when navigated into overlay
+            if (navStack.isNotEmpty()) {
+                SinglePaneHeader(
+                    title =
+                        when (currentOverlay) {
+                            is DesktopScreen.UserProfile -> "Profile"
+                            is DesktopScreen.Thread -> "Thread"
+                            else -> currentColumnType.title()
+                        },
+                    onBack = { navState.pop() },
+                )
+                HorizontalDivider()
+            }
+
+            Box(
+                modifier = Modifier.fillMaxSize().padding(12.dp),
+            ) {
+                if (currentOverlay != null) {
+                    OverlayContent(
+                        screen = currentOverlay,
+                        relayManager = relayManager,
+                        localCache = localCache,
+                        account = account,
+                        nwcConnection = nwcConnection,
+                        subscriptionsCoordinator = subscriptionsCoordinator,
+                        onShowComposeDialog = onShowComposeDialog,
+                        onShowReplyDialog = onShowReplyDialog,
+                        onZapFeedback = onZapFeedback,
+                        onNavigateToProfile = { navState.push(DesktopScreen.UserProfile(it)) },
+                        onNavigateToThread = { navState.push(DesktopScreen.Thread(it)) },
+                        onBack = { navState.pop() },
+                    )
+                } else {
+                    RootContent(
+                        columnType = currentColumnType,
+                        relayManager = relayManager,
+                        localCache = localCache,
+                        accountManager = accountManager,
+                        account = account,
+                        nwcConnection = nwcConnection,
+                        subscriptionsCoordinator = subscriptionsCoordinator,
+                        appScope = appScope,
+                        onShowComposeDialog = onShowComposeDialog,
+                        onShowReplyDialog = onShowReplyDialog,
+                        onZapFeedback = onZapFeedback,
+                        onNavigateToProfile = { navState.push(DesktopScreen.UserProfile(it)) },
+                        onNavigateToThread = { navState.push(DesktopScreen.Thread(it)) },
+                    )
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun SinglePaneHeader(
+    title: String,
+    onBack: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    Row(
+        modifier =
+            modifier
+                .fillMaxWidth()
+                .height(40.dp)
+                .background(MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.5f))
+                .padding(horizontal = 8.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        IconButton(onClick = onBack, modifier = Modifier.size(28.dp)) {
+            Icon(
+                Icons.AutoMirrored.Filled.ArrowBack,
+                contentDescription = "Back",
+                modifier = Modifier.size(16.dp),
+                tint = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+        Spacer(Modifier.width(8.dp))
+        Text(
+            text = title,
+            style = MaterialTheme.typography.labelLarge,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            maxLines = 1,
+            overflow = TextOverflow.Ellipsis,
+        )
+    }
+}