Refine Writing Desk collection and ink refill behavior

NOTICE

@@ -12,6 +12,10 @@ The Notebook page atlas is copied from Legacy's assets/mystcraft/gui/bookui_page
 under the same license.
 The Writing Desk item texture is copied from Legacy's
 assets/mystcraft/textures/items/writingdesk.png under the same license.
+The Writing Desk block texture is copied from Legacy's
+assets/mystcraft/textures/entity/desk.png under the same license.
+The Writing Desk GUI atlas is copied from Legacy's assets/mystcraft/gui/writingdesk.png
+under the same license; desk wood and inlay textures are cropped from desk.png.
 
 The initial build layout is derived from the official NeoForge 1.21.1
 ModDevGradle MDK: https://github.com/NeoForgeMDKs/MDK-1.21.1-ModDevGradle

README.md

@@ -14,23 +14,48 @@ have not been ported yet.
 Milestone 4 now includes stackable blank Pages plus server-created symbol,
 unresolved-symbol, and baseline link-panel states. Page visuals follow the
 legacy runtime-composition rules. Craft an Ink Vial from two black dye, a glass
-bottle, and a water bucket; the bucket is returned. Hold a blank Page in one
+bottle, and a water bucket; the bucket is returned. Hold vanilla paper in one
 hand and use the Ink Vial in the other to prepare a baseline Link Panel Page.
 Each vial holds 16 ink units, and the default link-panel cost is two units.
 The spent vial returns a glass bottle. Server owners can adjust the symbol-copy
 and link-panel costs in the `writing` section of `rivencraft-server.toml`.
 The Writing Desk can copy a selected written page from its collection tabs.
 The Writing Desk is now craftable from planks, a glass bottle, and a feather.
-Its four collection tabs, paper input, ink vial input, empty glass-bottle return,
+It occupies two adjacent blocks, with one shared inventory; loaded paper and
+the selected page appear on its Legacy-inspired model.
+Desks placed before 0.3.6.1 keep their old one-block footprint until broken
+and placed again; leave an adjacent space when replacing one.
+Its 88 collection tabs, paper input, ink vial input, empty glass-bottle return,
 16-unit ink meter, and inventory persist
 through world saves; breaking it drops stored contents. The desk screen is a
-functional foundation styled after Legacy's left tabs, central writing surface,
+functional foundation using Legacy's original desk and scrollbar textures.
-and right inventory. Put vanilla paper (or a blank Rivencraft Page) in the
+Four tabs are visible at once; the controls above and below them move by four
+(1–4, 5–8, through 85–88). Each viewer can browse a different group. Existing
+four-tab desks retain their collections and supplies when upgraded.
+With a notebook selected, pick up a Page from your inventory and click an empty
+position on the left surface to store one page there. Clear search/filter/sort
+and turn off `ALL` to place pages at specific positions; occupied positions are
+never overwritten. A notebook tab exposes all 27 notebook positions (scroll to
+reach the rest); a loose-page tab exposes only its one occupied position.
+Empty tabs have no page storage until a notebook or page is put in the tab slot.
+Click a page on the desk surface to select it for copying. Drag a page from one
+notebook position to an empty position to move it, or onto another page to swap
+their positions. This also works between notebooks shown in the `ALL` view.
+Drag a page out of the panel to turn it back into an item. Drop it over a player
+inventory slot or desk tab to place it there; a tab with a notebook adds it to
+the first open position. Dropping elsewhere leaves the page on the cursor for
+normal inventory placement. The source notebook or tab loses the page only after
+a valid drop.
+Put vanilla paper in the
 upper-left slot and Ink Vials in the upper-right; a copy appears in the
 lower-left result slot when the selected page is valid. Taking it consumes one
-paper and, by default, one ink. An empty meter consumes a vial to refill and
+paper and, by default, one ink. An available vial refills an empty ink meter
-returns a vanilla glass bottle to the lower-right slot. Writing new symbols
+when inserted or when copying uses its last ink, and returns a vanilla glass
-from a catalog remains future work.
+bottle to the lower-right slot. Removing a bottle also retries a blocked refill.
+Refilling waits if that slot is full or contains another item. The `AZ` control sorts
+visible pages by name; `ALL` shows pages held across every desk tab. Search and
+category filtering narrow the view without granting new pages, and cross-tab
+copy selection is checked by the server.
 Selecting a stored page on the desk surface shows its Legacy-proportioned
 portrait preview and name above the player inventory.
 

docs/ASSET_PROVENANCE.md

@@ -9,6 +9,10 @@ project's GNU LGPL v3 license. Rivencraft itself uses the same license.
 | `assets/rivencraft/textures/item/page.png` | `assets/mystcraft/textures/items/page_background.png` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Namespace/path rename only |
 | `assets/rivencraft/textures/gui/notebook_pages.png` | `assets/mystcraft/gui/bookui_pagel.png` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Namespace/path rename only; Notebook draws the native 30×40 page at atlas coordinates `(156, 0)` |
 | `assets/rivencraft/textures/item/writing_desk.png` | `assets/mystcraft/textures/items/writingdesk.png` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Namespace/path rename only |
+| `assets/rivencraft/textures/block/writing_desk.png` | `assets/mystcraft/textures/entity/desk.png` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Namespace/path rename only |
+| `assets/rivencraft/textures/block/writing_desk_wood.png` and `writing_desk_inlay.png` | `assets/mystcraft/textures/entity/desk.png` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Cropped opaque wood and red inlay regions for the two-block model |
+| `assets/rivencraft/textures/gui/writing_desk_legacy.png` | `assets/mystcraft/gui/writingdesk.png` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Namespace/path rename only; full desk panel, tabs, and cycling controls at original atlas coordinates |
+| `assets/rivencraft/textures/gui/scrollbar.png` | `assets/mystcraft/gui/scrollbar.png` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Namespace/path rename only; tiled track and normal/pressed thumb |
 | `assets/rivencraft/textures/item/linking_book_unwritten.png` | `assets/mystcraft/textures/items/unlinked.png` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Namespace/path rename only |
 | `assets/rivencraft/textures/item/page_link_panel.png` | `page_background.png` and `PageBuilder.BasicPageSprite` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Reproduces the legacy 160 px scale, black panel at `(25,30)`–`(135,75)`, and 128 px resample |
 | `assets/rivencraft/textures/item/page_symbol*.png` and `page_unresolved.png` | `page_background.png`, `textures/symbolcomponents.png`, `WordData`, `ModSymbols`, and `PageBuilder.PageSprite` | `9bc8ddc061845df0cd5ea47f4fdef773cff786ae` | Static 1.21.1 renditions of the legacy runtime-composed four-word symbol pages; `normal_time` uses the legacy Full Length poem |

docs/WRITING_DATA.md

@@ -53,8 +53,8 @@ unresolved symbol, and baseline link panel. Symbol and unresolved-symbol pages
 retain their namespaced symbol reference; unresolved pages can be inspected and
 removed but are rejected as usable writing until their data pack returns.
 
-Only server-side writing operations may turn a blank page into a known symbol
+Only server-side writing operations may create a known symbol
-page or link panel. The shared `PageItem` creation and validation gates reject
+page or link panel from vanilla paper. The shared `PageItem` creation and validation gates reject
 new pages for identifiers absent from the server catalog. Later Writing Desk
 and Book Binder packets must call these gates rather than accepting page
 contents supplied by a client.
@@ -82,9 +82,9 @@ used to craft another. The animated item texture comes from Mystcraft Legacy.
 
 The server config sets ink costs independently for symbol copying (default one
 unit) and baseline link-panel preparation (default two units). To prepare a
-panel, hold a blank Page in one hand and use an Ink Vial in the other. The
+panel, hold vanilla paper in one hand and use an Ink Vial in the other. The
-server checks the held items, blank state, and sufficient ink before consuming
+server checks the held items and sufficient ink before consuming
-anything. A stack of blank Pages yields exactly one Link Panel Page per use;
+anything. A stack of paper yields exactly one Link Panel Page per use;
 if the inventory is full, the result is dropped instead of deleted. Symbol
 copying is implemented by the Writing Desk: it previews a copy of the selected
 resolved page, then spends paper and ink only when that copy is taken. The

gradle.properties

@@ -35,7 +35,7 @@ mod_name=Rivencraft
 # The license of the mod. Review your options at https://choosealicense.com/. All Rights Reserved is the default.
 mod_license=LGPL-3.0-or-later
 # The mod version. Rivencraft uses the x.y.z.b policy documented in README.md.
-mod_version=0.3.5.2
+mod_version=0.3.6.8
 immersive_portals_version=6.0.7
 # The group ID for the mod. It is only important when publishing as an artifact to a Maven repository.
 # This should match the base package used for the mod sources.

src/main/java/net/dnorberg/rivencraft/block/WritingDeskBlock.java

@@ -3,7 +3,9 @@ package net.dnorberg.rivencraft.block;
 import com.mojang.serialization.MapCodec;
 import net.dnorberg.rivencraft.block.entity.WritingDeskBlockEntity;
 import net.dnorberg.rivencraft.menu.WritingDeskMenu;
+import net.dnorberg.rivencraft.writing.WritingDeskCatalog;
 import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
 import net.minecraft.network.chat.Component;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Containers;
@@ -18,45 +20,72 @@ import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.block.state.StateDefinition;
 import net.minecraft.world.level.block.state.properties.BlockStateProperties;
 import net.minecraft.world.level.block.state.properties.DirectionProperty;
+import net.minecraft.world.level.block.state.properties.BooleanProperty;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.entity.LivingEntity;
+import org.jetbrains.annotations.Nullable;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.phys.BlockHitResult;
 
 public final class WritingDeskBlock extends BaseEntityBlock {
     public static final MapCodec<WritingDeskBlock> CODEC = simpleCodec(WritingDeskBlock::new);
     public static final DirectionProperty FACING = BlockStateProperties.HORIZONTAL_FACING;
+    public static final BooleanProperty EXTENSION = BooleanProperty.create("extension");
 
     public WritingDeskBlock(Properties properties) {
         super(properties);
-        registerDefaultState(stateDefinition.any().setValue(FACING, net.minecraft.core.Direction.NORTH));
+        registerDefaultState(stateDefinition.any().setValue(FACING, Direction.NORTH).setValue(EXTENSION, false));
     }
 
     @Override public MapCodec<? extends BaseEntityBlock> codec() { return CODEC; }
     @Override protected void createBlockStateDefinition(StateDefinition.Builder<net.minecraft.world.level.block.Block, BlockState> builder) {
-        builder.add(FACING);
+        builder.add(FACING, EXTENSION);
     }
     @Override public BlockState getStateForPlacement(BlockPlaceContext context) {
-        return defaultBlockState().setValue(FACING, context.getHorizontalDirection().getOpposite());
+        Direction facing = context.getHorizontalDirection().getOpposite();
+        BlockPos extension = context.getClickedPos().relative(facing.getClockWise());
+        return context.getLevel().getBlockState(extension).canBeReplaced(context)
+                ? defaultBlockState().setValue(FACING, facing) : null;
+    }
+    @Override public void setPlacedBy(Level level, BlockPos pos, BlockState state,
+                                      @Nullable LivingEntity placer, ItemStack stack) {
+        super.setPlacedBy(level, pos, state, placer, stack);
+        level.setBlock(pos.relative(state.getValue(FACING).getClockWise()),
+                state.setValue(EXTENSION, true), 3);
     }
     @Override protected RenderShape getRenderShape(BlockState state) { return RenderShape.MODEL; }
     @Override public BlockEntity newBlockEntity(BlockPos pos, BlockState state) {
-        return new WritingDeskBlockEntity(pos, state);
+        return state.getValue(EXTENSION) ? null : new WritingDeskBlockEntity(pos, state);
     }
     @Override protected InteractionResult useWithoutItem(BlockState state, Level level, BlockPos pos,
                                                           Player player, BlockHitResult hit) {
+        BlockPos controller = state.getValue(EXTENSION)
+                ? pos.relative(state.getValue(FACING).getCounterClockWise()) : pos;
         if (!level.isClientSide && player instanceof ServerPlayer serverPlayer
-                && level.getBlockEntity(pos) instanceof WritingDeskBlockEntity desk) {
+                && level.getBlockEntity(controller) instanceof WritingDeskBlockEntity desk) {
             serverPlayer.openMenu(new SimpleMenuProvider(
                     (id, inventory, ignored) -> new WritingDeskMenu(id, inventory, desk),
                     Component.translatable("container.rivencraft.writing_desk")),
-                    buffer -> buffer.writeBlockPos(pos));
+                    buffer -> {
+                        buffer.writeBlockPos(controller);
+                        WritingDeskCatalog.write(buffer, WritingDeskCatalog.available(desk));
+                    });
         }
         return InteractionResult.sidedSuccess(level.isClientSide);
     }
     @Override protected void onRemove(BlockState state, Level level, BlockPos pos, BlockState replacement, boolean moving) {
-        if (!state.is(replacement.getBlock()) && !level.isClientSide
+        if (!state.is(replacement.getBlock())) {
-                && level.getBlockEntity(pos) instanceof WritingDeskBlockEntity desk) {
+            if (!level.isClientSide && !state.getValue(EXTENSION)
-            Containers.dropContents(level, pos, desk);
+                    && level.getBlockEntity(pos) instanceof WritingDeskBlockEntity desk) {
-            level.updateNeighbourForOutputSignal(pos, this);
+                Containers.dropContents(level, pos, desk);
+                level.updateNeighbourForOutputSignal(pos, this);
+            }
+            BlockPos other = pos.relative(state.getValue(FACING).getClockWise(),
+                    state.getValue(EXTENSION) ? -1 : 1);
+            BlockState otherState = level.getBlockState(other);
+            if (otherState.is(this) && otherState.getValue(EXTENSION) != state.getValue(EXTENSION)) {
+                level.setBlock(other, net.minecraft.world.level.block.Blocks.AIR.defaultBlockState(), 35);
+            }
         }
         super.onRemove(state, level, pos, replacement, moving);
     }

src/main/java/net/dnorberg/rivencraft/block/entity/WritingDeskBlockEntity.java

@@ -1,7 +1,6 @@
 package net.dnorberg.rivencraft.block.entity;
 
 import net.dnorberg.rivencraft.item.InkVialItem;
-import net.dnorberg.rivencraft.item.PageItem;
 import net.dnorberg.rivencraft.writing.WritingInkService;
 import net.dnorberg.rivencraft.registry.ModBlockEntities;
 import net.dnorberg.rivencraft.registry.ModItems;
@@ -9,26 +8,31 @@ import net.minecraft.core.BlockPos;
 import net.minecraft.core.HolderLookup;
 import net.minecraft.core.NonNullList;
 import net.minecraft.nbt.CompoundTag;
+import net.minecraft.network.protocol.Packet;
+import net.minecraft.network.protocol.game.ClientGamePacketListener;
+import net.minecraft.network.protocol.game.ClientboundBlockEntityDataPacket;
 import net.minecraft.world.Container;
 import net.minecraft.world.ContainerHelper;
 import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.Items;
+import net.minecraft.world.level.Level;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.level.block.state.BlockState;
 
-/** Four collection tabs, paper, ink vials and empty-vial return are owned by the block. */
+/** Collection tabs, paper, ink vials and empty-vial return are owned by the block. */
 public final class WritingDeskBlockEntity extends BlockEntity implements Container {
-    public static final int COLLECTIONS = 4;
+    public static final int COLLECTIONS = 88;
-    public static final int INK = 4;
+    public static final int INK = COLLECTIONS;
-    public static final int RETURN = 5;
+    public static final int RETURN = INK + 1;
-    public static final int PAPER = 6;
+    public static final int PAPER = INK + 2;
     /** Unused by new desks; retained so old saves cannot silently lose slot contents. */
-    public static final int LEGACY_OUTPUT = 7;
+    public static final int LEGACY_OUTPUT = INK + 3;
-    public static final int SIZE = 8;
+    public static final int SIZE = INK + 4;
     private NonNullList<ItemStack> items = NonNullList.withSize(SIZE, ItemStack.EMPTY);
     private int activeCollection;
     private int inkRemaining;
+    private ItemStack displayPage = ItemStack.EMPTY;
 
     public WritingDeskBlockEntity(BlockPos pos, BlockState state) {
         super(ModBlockEntities.WRITING_DESK.get(), pos, state);
@@ -36,6 +40,14 @@ public final class WritingDeskBlockEntity extends BlockEntity implements Contain
 
     public int activeCollection() { return activeCollection; }
     public int inkRemaining() { return inkRemaining; }
+    public ItemStack displayPage() { return displayPage; }
+    public void setDisplayPage(ItemStack page) {
+        ItemStack next = page.isEmpty() ? ItemStack.EMPTY : page.copyWithCount(1);
+        if (!ItemStack.matches(displayPage, next)) {
+            displayPage = next;
+            setChanged();
+        }
+    }
     public void setActiveCollection(int index) {
         if (index >= 0 && index < COLLECTIONS && activeCollection != index) {
             activeCollection = index;
@@ -48,14 +60,20 @@ public final class WritingDeskBlockEntity extends BlockEntity implements Contain
     @Override public ItemStack getItem(int slot) { return items.get(slot); }
     @Override public ItemStack removeItem(int slot, int amount) {
         ItemStack removed = ContainerHelper.removeItem(items, slot, amount);
-        if (!removed.isEmpty()) setChanged();
+        if (!removed.isEmpty()) {
+            if (slot < COLLECTIONS) displayPage = ItemStack.EMPTY;
+            setChanged();
+            if (slot == RETURN) refillEmptyInkBar();
+        }
         return removed;
     }
     @Override public ItemStack removeItemNoUpdate(int slot) { return ContainerHelper.takeItem(items, slot); }
     @Override public void setItem(int slot, ItemStack stack) {
         items.set(slot, stack);
         if (stack.getCount() > getMaxStackSize()) stack.setCount(getMaxStackSize());
+        if (slot < COLLECTIONS) displayPage = ItemStack.EMPTY;
         setChanged();
+        if (slot == INK || slot == RETURN) refillEmptyInkBar();
     }
     @Override public boolean stillValid(Player player) {
         return level != null && level.isLoaded(worldPosition)
@@ -68,14 +86,34 @@ public final class WritingDeskBlockEntity extends BlockEntity implements Contain
         return switch (slot) {
             case INK -> stack.is(ModItems.INK_VIAL.get());
             case RETURN -> false;
-            case PAPER -> stack.is(Items.PAPER)
+            case PAPER -> stack.is(Items.PAPER);
-                    || stack.is(ModItems.PAGE.get()) && PageItem.content(stack).kind()
-                    == net.dnorberg.rivencraft.writing.PageContent.Kind.BLANK;
             case LEGACY_OUTPUT -> false;
             default -> false;
         };
     }
 
+    private boolean hasBottleSpace() {
+        ItemStack returned = items.get(RETURN);
+        return returned.isEmpty() || returned.is(Items.GLASS_BOTTLE)
+                && returned.getCount() < returned.getMaxStackSize();
+    }
+
+    /** Consume one vial only when the empty meter can return its glass bottle. */
+    private void refillEmptyInkBar() {
+        if (level == null || level.isClientSide || inkRemaining != 0 || !hasBottleSpace()) return;
+        ItemStack vial = items.get(INK);
+        if (!vial.is(ModItems.INK_VIAL.get())) return;
+        int ink = Math.clamp(InkVialItem.remaining(vial), 0, InkVialItem.CAPACITY);
+        if (ink == 0) return;
+        inkRemaining = ink;
+        vial.shrink(1);
+        if (vial.isEmpty()) items.set(INK, ItemStack.EMPTY);
+        ItemStack returned = items.get(RETURN);
+        if (returned.isEmpty()) items.set(RETURN, new ItemStack(Items.GLASS_BOTTLE));
+        else returned.grow(1);
+        setChanged();
+    }
+
     /** The output is virtual; inputs are committed only after a result can be given to a player. */
     public boolean canConsumeCopyMaterials() {
         ItemStack paper = items.get(PAPER);
@@ -83,10 +121,8 @@ public final class WritingDeskBlockEntity extends BlockEntity implements Contain
         int cost = WritingInkService.symbolCopyCost();
         if (inkRemaining >= cost) return true;
         ItemStack vial = items.get(INK);
-        ItemStack returned = items.get(RETURN);
         return vial.is(ModItems.INK_VIAL.get()) && inkRemaining + InkVialItem.remaining(vial) >= cost
-                && (returned.isEmpty() || returned.is(Items.GLASS_BOTTLE)
+                && hasBottleSpace();
-                && returned.getCount() < returned.getMaxStackSize());
     }
 
     public boolean consumeCopyMaterials() {
@@ -104,25 +140,57 @@ public final class WritingDeskBlockEntity extends BlockEntity implements Contain
         inkRemaining -= cost;
         removeItem(PAPER, 1);
         setChanged();
+        if (inkRemaining == 0) refillEmptyInkBar();
         return true;
     }
+    @Override public void setLevel(Level level) {
+        super.setLevel(level);
+        refillEmptyInkBar();
+    }
     @Override public void clearContent() {
         items.clear();
         items = NonNullList.withSize(SIZE, ItemStack.EMPTY);
         inkRemaining = 0;
+        displayPage = ItemStack.EMPTY;
         setChanged();
     }
     @Override protected void loadAdditional(CompoundTag tag, HolderLookup.Provider registries) {
         super.loadAdditional(tag, registries);
         items = NonNullList.withSize(SIZE, ItemStack.EMPTY);
         ContainerHelper.loadAllItems(tag, items, registries);
+        // Pre-88-tab desks stored materials in slots 4..7. Move them once;
+        // never interpret those stacks as newly added collection tabs.
+        if (tag.getInt("InventoryVersion") < 1) {
+            for (int i = 0; i < 4; i++) {
+                items.set(INK + i, items.get(4 + i));
+                items.set(4 + i, ItemStack.EMPTY);
+            }
+        }
         activeCollection = Math.clamp(tag.getInt("ActiveCollection"), 0, COLLECTIONS - 1);
         inkRemaining = Math.clamp(tag.getInt("InkRemaining"), 0, InkVialItem.CAPACITY);
+        displayPage = tag.contains("DisplayPage", CompoundTag.TAG_COMPOUND)
+                ? ItemStack.parse(registries, tag.getCompound("DisplayPage")).orElse(ItemStack.EMPTY)
+                : ItemStack.EMPTY;
+        refillEmptyInkBar();
     }
     @Override protected void saveAdditional(CompoundTag tag, HolderLookup.Provider registries) {
         super.saveAdditional(tag, registries);
         ContainerHelper.saveAllItems(tag, items, registries);
+        tag.putInt("InventoryVersion", 1);
         tag.putInt("ActiveCollection", activeCollection);
         tag.putInt("InkRemaining", inkRemaining);
+        if (!displayPage.isEmpty()) tag.put("DisplayPage", displayPage.save(registries));
+    }
+    @Override public Packet<ClientGamePacketListener> getUpdatePacket() {
+        return ClientboundBlockEntityDataPacket.create(this);
+    }
+    @Override public CompoundTag getUpdateTag(HolderLookup.Provider registries) {
+        return saveWithoutMetadata(registries);
+    }
+    @Override public void setChanged() {
+        super.setChanged();
+        if (level != null && !level.isClientSide) {
+            level.sendBlockUpdated(worldPosition, getBlockState(), getBlockState(), 2);
+        }
     }
 }

src/main/java/net/dnorberg/rivencraft/client/ClientEvents.java

@@ -25,6 +25,7 @@ public final class ClientEvents {
     @SubscribeEvent
     public static void registerRenderers(EntityRenderersEvent.RegisterRenderers event) {
         event.registerBlockEntityRenderer(ModBlockEntities.BOOK_STAND.get(), BookStandRenderer::new);
+        event.registerBlockEntityRenderer(ModBlockEntities.WRITING_DESK.get(), WritingDeskRenderer::new);
     }
 
     @SubscribeEvent

src/main/java/net/dnorberg/rivencraft/client/ClientWritingDeskCatalog.java

@@ -0,0 +1,20 @@
+package net.dnorberg.rivencraft.client;
+
+import net.dnorberg.rivencraft.menu.WritingDeskMenu;
+import net.dnorberg.rivencraft.network.WritingDeskCatalogPayload;
+import net.minecraft.client.Minecraft;
+import net.neoforged.neoforge.network.handling.IPayloadContext;
+
+public final class ClientWritingDeskCatalog {
+    private ClientWritingDeskCatalog() {}
+
+    public static void handle(WritingDeskCatalogPayload payload, IPayloadContext context) {
+        context.enqueueWork(() -> {
+            var player = Minecraft.getInstance().player;
+            if (player != null && player.containerMenu instanceof WritingDeskMenu menu
+                    && menu.containerId == payload.containerId()) {
+                menu.setCatalog(payload.symbols());
+            }
+        });
+    }
+}

src/main/java/net/dnorberg/rivencraft/client/WritingDeskRenderer.java

@@ -0,0 +1,55 @@
+package net.dnorberg.rivencraft.client;
+
+import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.math.Axis;
+import net.dnorberg.rivencraft.block.WritingDeskBlock;
+import net.dnorberg.rivencraft.block.entity.WritingDeskBlockEntity;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.MultiBufferSource;
+import net.minecraft.client.renderer.blockentity.BlockEntityRenderer;
+import net.minecraft.client.renderer.blockentity.BlockEntityRendererProvider;
+import net.minecraft.world.item.ItemDisplayContext;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+
+/** Visible selected page and loaded paper, as on the Legacy desk. */
+public final class WritingDeskRenderer implements BlockEntityRenderer<WritingDeskBlockEntity> {
+    public WritingDeskRenderer(BlockEntityRendererProvider.Context context) {}
+
+    @Override public void render(WritingDeskBlockEntity desk, float partialTick, PoseStack pose,
+                                 MultiBufferSource buffers, int light, int overlay) {
+        int paper = desk.getItem(WritingDeskBlockEntity.PAPER).getCount();
+        ItemStack page = desk.displayPage();
+        if (paper == 0 && page.isEmpty()) return;
+        pose.pushPose();
+        pose.translate(0.5, 0, 0.5);
+        pose.mulPose(Axis.YP.rotationDegrees(
+                180.0F - desk.getBlockState().getValue(WritingDeskBlock.FACING).toYRot()));
+        if (paper > 0) {
+            ItemStack sheet = new ItemStack(Items.PAPER);
+            int layers = Math.min(4, 1 + paper / 16);
+            for (int i = 0; i < layers; i++) {
+                drawFlat(desk, sheet, pose, buffers, light, overlay, 1.22, 0.27 + i * 0.008, -0.14, 0.55F);
+            }
+        }
+        if (!page.isEmpty()) {
+            drawFlat(desk, page, pose, buffers, light, overlay, 1.0, 0.572, 0.0, 0.8F);
+        }
+        pose.popPose();
+    }
+
+    private static void drawFlat(WritingDeskBlockEntity desk, ItemStack stack, PoseStack pose,
+                                 MultiBufferSource buffers, int light, int overlay,
+                                 double x, double y, double z, float scale) {
+        pose.pushPose();
+        pose.translate(x, y, z);
+        pose.mulPose(Axis.XP.rotationDegrees(90));
+        pose.scale(scale, scale, scale);
+        Minecraft.getInstance().getItemRenderer().renderStatic(stack, ItemDisplayContext.FIXED,
+                light, overlay, pose, buffers, desk.getLevel(), 0);
+        pose.popPose();
+    }
+
+    @Override public boolean shouldRenderOffScreen(WritingDeskBlockEntity blockEntity) { return true; }
+    @Override public int getViewDistance() { return 64; }
+}

src/main/java/net/dnorberg/rivencraft/client/screen/NotebookScreen.java

@@ -276,7 +276,11 @@ public final class NotebookScreen extends AbstractContainerScreen<NotebookMenu>
         if (content.kind() == net.dnorberg.rivencraft.writing.PageContent.Kind.UNRESOLVED_SYMBOL) {
             return UNRESOLVED_SYMBOL;
         }
-        return switch (content.symbol().orElseThrow().id().toString()) {
+        return symbolTexture(content.symbol().orElseThrow().id());
+    }
+
+    static ResourceLocation symbolTexture(ResourceLocation id) {
+        return switch (id.toString()) {
             case "rivencraft:terrain/standard" -> STANDARD_TERRAIN;
             case "rivencraft:biome/native" -> NATIVE_BIOMES;
             case "rivencraft:lighting/normal" -> NORMAL_LIGHTING;

src/main/java/net/dnorberg/rivencraft/client/screen/WritingDeskScreen.java

@@ -1,91 +1,215 @@
 package net.dnorberg.rivencraft.client.screen;
 
 import java.util.List;
+import java.util.Locale;
+import java.util.ArrayList;
+import java.util.Comparator;
 import net.dnorberg.rivencraft.Rivencraft;
 import net.dnorberg.rivencraft.item.PageItem;
 import net.dnorberg.rivencraft.menu.WritingDeskMenu;
+import net.dnorberg.rivencraft.block.entity.WritingDeskBlockEntity;
 import net.dnorberg.rivencraft.registry.ModDataComponents;
 import net.dnorberg.rivencraft.registry.ModItems;
 import net.dnorberg.rivencraft.writing.NotebookContents;
+import net.dnorberg.rivencraft.writing.SymbolDisplayMetadata;
 import net.minecraft.client.gui.GuiGraphics;
+import net.minecraft.client.gui.components.Button;
+import net.minecraft.client.gui.components.EditBox;
 import net.minecraft.client.gui.screens.inventory.AbstractContainerScreen;
 import net.minecraft.network.chat.Component;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.inventory.Slot;
 import net.minecraft.world.item.ItemStack;
 
-/** Functional storage surface; full Legacy transcription controls are a later Milestone 4 slice. */
+/** Legacy desk atlas layout, with four visible tabs out of the desk's 88 collections. */
 public final class WritingDeskScreen extends AbstractContainerScreen<WritingDeskMenu> {
     private static final ResourceLocation PAGE_ATLAS = ResourceLocation.fromNamespaceAndPath(
             Rivencraft.MOD_ID, "textures/gui/notebook_pages.png");
+    private static final ResourceLocation LEGACY_DESK = ResourceLocation.fromNamespaceAndPath(
+            Rivencraft.MOD_ID, "textures/gui/writing_desk_legacy.png");
+    private static final ResourceLocation SCROLLBAR = ResourceLocation.fromNamespaceAndPath(
+            Rivencraft.MOD_ID, "textures/gui/scrollbar.png");
     private int lastCollection = -1;
     private int selectedPage;
     private int scrollRows;
+    private boolean allMode;
+    private boolean sortAlphabetically;
+    private int selectedCollection = -1;
+    private ResourceLocation selectedCategory;
+    private EditBox search;
+    private Button categoryButton;
+    private Button allButton;
+    private Button sortButton;
+    private boolean draggingScrollbar;
+    private record DisplayPage(int collection, int index, ItemStack stack) {}
+    private DisplayPage pageDragSource;
+    private double pageDragStartX;
+    private double pageDragStartY;
+    private boolean draggingPage;
+
+    private boolean isPhysicalPageView() {
+        return !allMode && !sortAlphabetically && selectedCategory == null
+                && (search == null || search.getValue().isBlank());
+    }
 
     public WritingDeskScreen(WritingDeskMenu menu, Inventory inventory, Component title) {
         super(menu, inventory, title);
-        imageWidth = 398;
+        imageWidth = 409;
-        imageHeight = 176;
+        imageHeight = 186;
         titleLabelX = 222;
-        inventoryLabelX = 224;
+    }
-        inventoryLabelY = 79;
+
+    @Override protected void init() {
+        super.init();
+        sortButton = addRenderableWidget(Button.builder(Component.literal("AZ"), button -> {
+            sortAlphabetically = !sortAlphabetically;
+            scrollRows = 0;
+        }).bounds(leftPos + 58, topPos, 20, 18).build());
+        allButton = addRenderableWidget(Button.builder(Component.literal("ALL"), button -> {
+            allMode = !allMode;
+            scrollRows = 0;
+            if (!allMode) {
+                selectedCollection = -1;
+                selectedPage = 0;
+                if (minecraft != null && minecraft.gameMode != null)
+                    minecraft.gameMode.handleInventoryButtonClick(menu.containerId, WritingDeskMenu.PAGE_BUTTON_BASE);
+            }
+        }).bounds(leftPos + 80, topPos, 28, 18).build());
+        search = new EditBox(font, leftPos + 110, topPos, 101, 18,
+                Component.translatable("screen.rivencraft.writing_desk.search"));
+        search.setMaxLength(64);
+        search.setHint(Component.translatable("screen.rivencraft.writing_desk.search"));
+        search.setResponder(value -> scrollRows = 0);
+        addRenderableWidget(search);
+        categoryButton = addRenderableWidget(Button.builder(Component.literal("C"), button -> {
+            List<ResourceLocation> categories = menu.catalog().stream()
+                    .map(SymbolDisplayMetadata::category).distinct().sorted().toList();
+            int next = selectedCategory == null ? 0 : categories.indexOf(selectedCategory) + 1;
+            selectedCategory = next >= categories.size() ? null : categories.get(next);
+            categoryButton.setMessage(Component.literal(selectedCategory == null ? "C" : "C*"));
+            scrollRows = 0;
+        }).bounds(leftPos + 213, topPos, 18, 18).build());
+    }
+
+    private List<DisplayPage> filteredPages() {
+        String query = search == null ? "" : search.getValue().trim().toLowerCase(Locale.ROOT);
+        List<DisplayPage> entries = new ArrayList<>();
+        int from = allMode ? 0 : menu.activeCollection();
+        int until = allMode ? WritingDeskBlockEntity.COLLECTIONS : from + 1;
+        for (int collection = from; collection < until; collection++) {
+            List<ItemStack> pages = pages(collection);
+            int last = -1;
+            for (int i = 0; i < pages.size(); i++) if (!pages.get(i).isEmpty()) last = i;
+            // A notebook has exactly its normal GUI capacity; a loose page has one position.
+            if (isPhysicalPageView()) last = menu.pageCapacity(collection) - 1;
+            for (int i = 0; i <= last; i++) {
+                ItemStack page = i < pages.size() ? pages.get(i) : ItemStack.EMPTY;
+                if (page.isEmpty() && (allMode || sortAlphabetically || !query.isEmpty() || selectedCategory != null)) continue;
+                if (!page.isEmpty() && !query.isEmpty()
+                        && !page.getHoverName().getString().toLowerCase(Locale.ROOT).contains(query)
+                        && !PageItem.content(page).symbol().map(symbol -> symbol.id().toString()
+                        .toLowerCase(Locale.ROOT).contains(query)).orElse(false)) continue;
+                if (!page.isEmpty() && selectedCategory != null) {
+                    ResourceLocation id = PageItem.content(page).symbol().map(symbol -> symbol.id()).orElse(null);
+                    if (menu.catalog().stream().noneMatch(metadata -> metadata.id().equals(id)
+                            && metadata.category().equals(selectedCategory))) continue;
+                }
+                entries.add(new DisplayPage(collection, i, page));
+            }
+        }
+        if (sortAlphabetically) entries.sort(Comparator
+                .comparing((DisplayPage entry) -> entry.stack().getHoverName().getString(), String.CASE_INSENSITIVE_ORDER)
+                .thenComparingInt(DisplayPage::collection).thenComparingInt(DisplayPage::index));
+        return entries;
     }
 
     @Override public void renderBackground(GuiGraphics graphics, int mouseX, int mouseY, float partialTick) {
-        // Legacy leaves the world visible around the desk instead of dimming it.
+        // Keep the world visible, but still draw our GUI backing. The vanilla
+        // container implementation normally calls renderBg from this method.
+        renderBg(graphics, partialTick, mouseX, mouseY);
     }
 
     @Override protected void renderBg(GuiGraphics graphics, float partialTick, int mouseX, int mouseY) {
         int x = leftPos;
         int y = topPos;
-        graphics.fill(x + 4, y + 8, x + 216, y + 174, 0xFF383230);
+        // Legacy GuiWritingDesk draws the entire 176x166 panel, not a stretched swatch.
-        graphics.fill(x + 44, y + 14, x + 210, y + 170, 0xFF221B1A);
+        graphics.blit(LEGACY_DESK, x + 233, y + 20, 0, 0, 176, 166);
-        graphics.fill(x + 218, y + 4, x + 396, y + 174, 0xFF555454);
+        drawTabControl(graphics, 20, 203, menu.firstVisibleTab() > 0);
-        graphics.fill(x + 220, y + 6, x + 394, y + 172, 0xFFB7B7B7);
         for (int i = 0; i < 4; i++) {
-            graphics.fill(x + 6, y + 16 + i * 37, x + 40, y + 48 + i * 37,
+            int tab = menu.firstVisibleTab() + i;
-                    i == menu.activeCollection() ? 0xFF7777B6 : 0xFF999999);
+            int tabY = y + 29 + i * 37;
-            slotFrame(graphics, 12, 20 + i * 37);
+            if (tab == menu.activeCollection() && !allMode) graphics.setColor(0.5F, 0.5F, 1F, 1F);
+            graphics.blit(LEGACY_DESK, x, tabY, 0, 166, 58, 37);
+            graphics.setColor(1F, 1F, 1F, 1F);
+            graphics.drawString(font, Integer.toString(tab + 1), x + 8, tabY + 8, 0xFF181818, false);
+            ItemStack collection = menu.getSlot(tab).getItem();
+            if (!collection.isEmpty()) {
+                String name = collection.getHoverName().getString();
+                float scale = Math.min(1F, 50F / Math.max(1, font.width(name)));
+                graphics.pose().pushPose();
+                graphics.pose().translate(x + 4, tabY + 25, 0);
+                graphics.pose().scale(scale, scale, 1);
+                graphics.drawString(font, name, 0, 0, 0xFF404040, false);
+                graphics.pose().popPose();
+            }
         }
-        slotFrame(graphics, 370, 20);
+        drawTabControl(graphics, 177, 212, menu.firstVisibleTab() < WritingDeskBlockEntity.COLLECTIONS - 4);
-        slotFrame(graphics, 228, 20);
+        // GuiElementVSlider: 4-pixel caps, repeated 22-pixel track, 12x15 thumb.
-        slotFrame(graphics, 228, 57);
+        graphics.blit(SCROLLBAR, x + 213, y + 20, 0, 0, 20, 4, 32, 32);
-        slotFrame(graphics, 370, 57);
+        for (int offset = 4; offset < 162; offset += 22)
-        graphics.fill(x + 350, y + 20, x + 364, y + 75, 0xFF303035);
+            graphics.blit(SCROLLBAR, x + 213, y + 20 + offset, 0, 4, 20, Math.min(22, 162 - offset), 32, 32);
-        graphics.fill(x + 352, y + 22, x + 362, y + 73, 0xFF15151B);
+        graphics.blit(SCROLLBAR, x + 213, y + 182, 0, 26, 20, 4, 32, 32);
-        int filled = 51 * menu.inkRemaining() / 16;
+        int totalRows = (filteredPages().size() + 4) / 5;
-        if (filled > 0) graphics.fill(x + 352, y + 73 - filled, x + 362, y + 73, 0xFF6666AA);
+        int maxScroll = Math.max(0, totalRows - 4);
-        graphics.renderOutline(x + 350, y + 20, 14, 55, 0xFF484848);
+        scrollRows = Math.clamp(scrollRows, 0, maxScroll);
-        for (int row = 0; row < 3; row++) {
+        int thumbY = y + 24 + (maxScroll == 0 ? 0 : scrollRows * 143 / maxScroll);
-            for (int column = 0; column < 9; column++) slotFrame(graphics, 224 + column * 18, 91 + row * 18);
+        graphics.blit(SCROLLBAR, x + 217, thumbY, 20, draggingScrollbar ? 15 : 0, 12, 15, 32, 32);
-        }
+        graphics.fill(x + 365, y + 27, x + 381, y + 97, 0xFF303035);
-        for (int column = 0; column < 9; column++) slotFrame(graphics, 224 + column * 18, 149);
+        graphics.fill(x + 366, y + 28, x + 380, y + 96, 0xFF6666AA);
+        int filled = 68 * menu.inkRemaining() / 16;
+        if (filled > 0) graphics.fill(x + 366, y + 96 - filled, x + 380, y + 96, 0xFF15151B);
     }
 
-    private void slotFrame(GuiGraphics graphics, int x, int y) {
+    private void drawTabControl(GuiGraphics graphics, int y, int textureY, boolean enabled) {
-        graphics.fill(leftPos + x - 1, topPos + y - 1,
+        if (!enabled) graphics.setColor(0.4F, 0.4F, 0.4F, 1F);
-                leftPos + x + 17, topPos + y + 17, 0xFF4D4D4D);
+        graphics.blit(LEGACY_DESK, leftPos, topPos + y, 0, textureY, 58, 9);
-        graphics.fill(leftPos + x, topPos + y,
+        graphics.setColor(1F, 1F, 1F, 1F);
-                leftPos + x + 16, topPos + y + 16, 0xFF858585);
     }
 
     @Override protected void renderLabels(GuiGraphics graphics, int mouseX, int mouseY) {
-        graphics.drawString(font, playerInventoryTitle, inventoryLabelX, inventoryLabelY, 0x404040, false);
+        // Legacy leaves the inventory grid unlabeled.
     }
 
     @Override public void render(GuiGraphics graphics, int mouseX, int mouseY, float partialTick) {
         super.render(graphics, mouseX, mouseY, partialTick);
+        if (sortAlphabetically) graphics.renderOutline(leftPos + 58, topPos, 20, 18, 0xFFFFD061);
+        if (allMode) graphics.renderOutline(leftPos + 80, topPos, 28, 18, 0xFFFFD061);
         renderCollection(graphics);
+        if (draggingPage && pageDragSource != null) {
+            DisplayPage target = pageAtMouse(mouseX, mouseY);
+            if (target != null && canMovePage(pageDragSource, target)) {
+                int x = leftPos + 58 + ((int) mouseX - leftPos - 58) / 31 * 31;
+                int y = topPos + 20 + ((int) mouseY - topPos - 20) / 41 * 41;
+                graphics.renderOutline(x, y, 30, 40, 0xFF57D478);
+            }
+            graphics.renderItem(pageDragSource.stack(), mouseX - 8, mouseY - 8);
+        }
         renderTooltip(graphics, mouseX, mouseY);
-        if (mouseX >= leftPos + 350 && mouseX < leftPos + 364
+        if (mouseX >= leftPos + 365 && mouseX < leftPos + 381
-                && mouseY >= topPos + 20 && mouseY < topPos + 75) {
+                && mouseY >= topPos + 27 && mouseY < topPos + 97) {
             graphics.renderTooltip(font, Component.translatable("screen.rivencraft.writing_desk.ink",
                     menu.inkRemaining(), 16), mouseX, mouseY);
         }
+        if (mouseX >= leftPos + 213 && mouseX < leftPos + 231
+                && mouseY >= topPos && mouseY < topPos + 18) {
+            graphics.renderTooltip(font, Component.literal(selectedCategory == null
+                    ? "All categories" : selectedCategory.toString()), mouseX, mouseY);
+        }
     }
 
-    private List<ItemStack> pages() {
+    private List<ItemStack> pages(int collectionIndex) {
-        ItemStack collection = menu.getSlot(menu.activeCollection()).getItem();
+        ItemStack collection = menu.getSlot(collectionIndex).getItem();
         if (collection.is(ModItems.PAGE.get())) return List.of(collection);
         if (collection.is(ModItems.NOTEBOOK.get())) {
             return collection.getOrDefault(ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages();
@@ -94,34 +218,34 @@ public final class WritingDeskScreen extends AbstractContainerScreen<WritingDesk
     }
 
     private void renderCollection(GuiGraphics graphics) {
-        List<ItemStack> pages = pages();
         if (lastCollection != menu.activeCollection()) {
             lastCollection = menu.activeCollection();
             scrollRows = 0;
             selectedPage = 0;
+            selectedCollection = -1;
         }
-        int last = -1;
+        List<DisplayPage> entries = filteredPages();
-        for (int i = 0; i < pages.size(); i++) if (!pages.get(i).isEmpty()) last = i;
+        for (int i = scrollRows * 5; i < entries.size() && i < scrollRows * 5 + 20; i++) {
-        for (int i = scrollRows * 5; i <= last && i < scrollRows * 5 + 15; i++) {
             int column = i % 5;
             int row = i / 5 - scrollRows;
-            ItemStack page = pages.get(i);
+            DisplayPage entry = entries.get(i);
-            int x = leftPos + 48 + column * 31;
+            ItemStack page = entry.stack();
-            int y = topPos + 18 + row * 41;
+            int x = leftPos + 58 + column * 31;
+            int y = topPos + 20 + row * 41;
             drawPage(graphics, page, x, y);
             if (page.isEmpty()) graphics.fill(x, y, x + 30, y + 40, 0xB8000000);
-            if (i == selectedPage && !page.isEmpty()) graphics.renderOutline(x, y, 30, 40, 0xFFFFD061);
+            int active = selectedCollection >= 0 ? selectedCollection : menu.activeCollection();
+            if (entry.collection() == active && entry.index() == selectedPage && !page.isEmpty())
+                graphics.renderOutline(x, y, 30, 40, 0xFFFFD061);
         }
-        if (selectedPage >= pages.size() || pages.get(selectedPage).isEmpty()) return;
+        int active = selectedCollection >= 0 ? selectedCollection : menu.activeCollection();
-        ItemStack selected = pages.get(selectedPage);
+        List<ItemStack> source = pages(active);
-        graphics.pose().pushPose();
+        if (selectedPage >= source.size() || source.get(selectedPage).isEmpty()) return;
-        graphics.pose().translate(leftPos + 294, topPos + 12, 0);
+        ItemStack selected = source.get(selectedPage);
-        graphics.pose().scale(1.35F, 1.35F, 1.0F);
+        drawPage(graphics, selected, leftPos + 265, topPos + 26);
-        drawPage(graphics, selected, 0, 0);
+        String title = font.plainSubstrByWidth(selected.getHoverName().getString(), 95);
-        graphics.pose().popPose();
+        graphics.fill(leftPos + 261, topPos + 81, leftPos + 360, topPos + 95, 0xFF202020);
-        String title = font.plainSubstrByWidth(selected.getHoverName().getString(), 112);
+        graphics.drawString(font, title, leftPos + 263, topPos + 84, 0xFFE0E0E0, false);
-        graphics.fill(leftPos + 251, topPos + 64, leftPos + 365, topPos + 77, 0xFF202020);
-        graphics.drawString(font, title, leftPos + 254, topPos + 67, 0xFFE0E0E0, false);
     }
 
     private void drawPage(GuiGraphics graphics, ItemStack page, int x, int y) {
@@ -135,31 +259,116 @@ public final class WritingDeskScreen extends AbstractContainerScreen<WritingDesk
         }
     }
 
+    private DisplayPage pageAtMouse(double mouseX, double mouseY) {
+        int x = (int) Math.floor(mouseX - leftPos - 58);
+        int y = (int) Math.floor(mouseY - topPos - 20);
+        if (x < 0 || x >= 155 || y < 0 || y >= 164 || x % 31 >= 30 || y % 41 >= 40) return null;
+        int index = (y / 41 + scrollRows) * 5 + x / 31;
+        List<DisplayPage> entries = filteredPages();
+        return index < entries.size() ? entries.get(index) : null;
+    }
+
+    private boolean canMovePage(DisplayPage source, DisplayPage target) {
+        return !source.stack().isEmpty()
+                && (menu.getSlot(source.collection()).getItem().is(ModItems.NOTEBOOK.get())
+                    || menu.getSlot(source.collection()).getItem().is(ModItems.PAGE.get()))
+                && (menu.getSlot(target.collection()).getItem().is(ModItems.NOTEBOOK.get())
+                    || menu.getSlot(target.collection()).getItem().is(ModItems.PAGE.get()))
+                && (source.collection() != target.collection() || source.index() != target.index());
+    }
+
+    private int extractTargetSlot(double mouseX, double mouseY) {
+        for (Slot slot : menu.slots) {
+            int index = slot.index;
+            if (index >= WritingDeskBlockEntity.COLLECTIONS && index <= WritingDeskMenu.COPY_RESULT) continue;
+            if (!slot.isActive() || !isHovering(slot.x, slot.y, 16, 16, mouseX, mouseY)) continue;
+            ItemStack held = pageDragSource.stack();
+            if (!slot.mayPlace(held)) return -1;
+            ItemStack current = slot.getItem();
+            if (current.isEmpty()) return index;
+            if (index < WritingDeskBlockEntity.COLLECTIONS && current.is(ModItems.NOTEBOOK.get())) {
+                List<ItemStack> pages = current.getOrDefault(
+                        ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages();
+                if (pages.size() < NotebookContents.MAX_PAGES || pages.stream().anyMatch(ItemStack::isEmpty))
+                    return index;
+            } else if (index > WritingDeskMenu.COPY_RESULT && ItemStack.isSameItemSameComponents(current, held)
+                    && current.getCount() < slot.getMaxStackSize(held)) return index;
+            return -1;
+        }
+        return -1;
+    }
+
     @Override public boolean mouseClicked(double mouseX, double mouseY, int button) {
         if (button == 0) {
-            int x = (int) mouseX - leftPos - 48;
+            pageDragSource = null;
-            int y = (int) mouseY - topPos - 18;
+            draggingPage = false;
-            if (x >= 0 && x < 155 && y >= 0 && y < 123) {
+        }
-                int column = x / 31;
+        int surfaceX = (int) Math.floor(mouseX - leftPos - 58);
-                int row = y / 41;
+        int surfaceY = (int) Math.floor(mouseY - topPos - 20);
-                int index = (row + scrollRows) * 5 + column;
+        if ((button == 0 || button == 1) && !menu.getCarried().isEmpty()
-                List<ItemStack> pages = pages();
+                && surfaceX >= 0 && surfaceX < 155 && surfaceY >= 0 && surfaceY < 164) {
-                if (x % 31 < 30 && y % 41 < 40 && index < pages.size()
+            if (menu.getCarried().is(ModItems.PAGE.get()) && surfaceX % 31 < 30 && surfaceY % 41 < 40) {
-                        && !pages.get(index).isEmpty()) {
+                int index = (surfaceY / 41 + scrollRows) * 5 + surfaceX / 31;
-                    selectedPage = index;
+                List<DisplayPage> entries = filteredPages();
+                // Only displayed positions are addressable. Filtering never turns
+                // empty screen space into additional storage for a loose-page tab.
+                int collection = index < entries.size() ? entries.get(index).collection() : menu.activeCollection();
+                int page = index < entries.size() ? entries.get(index).index() : index;
+                if (index < entries.size() && page < menu.pageCapacity(collection)
+                        && minecraft != null && minecraft.gameMode != null) {
+                    minecraft.gameMode.handleInventoryButtonClick(menu.containerId,
+                            WritingDeskMenu.PLACE_PAGE_BUTTON_BASE + collection * NotebookContents.MAX_PAGES + page);
+                }
+            }
+            return true;
+        }
+        if (button == 0) {
+            if (mouseX >= leftPos && mouseX < leftPos + 58) {
+                int y = (int) mouseY - topPos;
+                if (y >= 20 && y < 29 || y >= 177 && y < 186) {
+                    if (minecraft != null && minecraft.gameMode != null)
+                        minecraft.gameMode.handleInventoryButtonClick(menu.containerId,
+                                y < 29 ? WritingDeskMenu.PREVIOUS_TABS : WritingDeskMenu.NEXT_TABS);
+                    return true;
+                }
+            }
+            if (mouseX >= leftPos + 213 && mouseX < leftPos + 233
+                    && mouseY >= topPos + 20 && mouseY < topPos + 186) {
+                draggingScrollbar = true;
+                setScrollFromMouse(mouseY);
+                return true;
+            }
+            int x = (int) Math.floor(mouseX - leftPos - 58);
+            int y = (int) Math.floor(mouseY - topPos - 20);
+            if (x >= 0 && x < 155 && y >= 0 && y < 164) {
+                DisplayPage entry = pageAtMouse(mouseX, mouseY);
+                if (entry != null && !entry.stack().isEmpty()) {
+                    selectedCollection = entry.collection();
+                    selectedPage = entry.index();
+                    if (menu.getCarried().isEmpty()) {
+                        pageDragSource = entry;
+                        pageDragStartX = mouseX;
+                        pageDragStartY = mouseY;
+                    }
                     if (minecraft != null && minecraft.gameMode != null) {
-                        minecraft.gameMode.handleInventoryButtonClick(menu.containerId, 16 + index);
+                        int id = WritingDeskMenu.ALL_PAGE_BUTTON_BASE
+                                + entry.collection() * NotebookContents.MAX_PAGES + entry.index();
+                        minecraft.gameMode.handleInventoryButtonClick(menu.containerId, id);
                     }
                 }
                 return true;
             }
         }
-        if (button == 0 && mouseX >= leftPos + 29 && mouseX < leftPos + 40) {
+        if (button == 0 && mouseX >= leftPos && mouseX < leftPos + 58) {
             for (int i = 0; i < 4; i++) {
-                int top = topPos + 16 + i * 37;
+                int top = topPos + 29 + i * 37;
-                if (mouseY >= top && mouseY < top + 32) {
+                boolean overSlot = mouseX >= leftPos + 36 && mouseX < leftPos + 54
+                        && mouseY >= top + 4 && mouseY < top + 22;
+                if (mouseY >= top && mouseY < top + 37 && !overSlot) {
+                    allMode = false;
+                    selectedCollection = -1;
                     if (minecraft != null && minecraft.gameMode != null) {
-                        minecraft.gameMode.handleInventoryButtonClick(menu.containerId, i);
+                        minecraft.gameMode.handleInventoryButtonClick(menu.containerId, menu.firstVisibleTab() + i);
                     }
                     return true;
                 }
@@ -169,12 +378,73 @@ public final class WritingDeskScreen extends AbstractContainerScreen<WritingDesk
     }
 
     @Override public boolean mouseScrolled(double mouseX, double mouseY, double scrollX, double scrollY) {
-        if (mouseX >= leftPos + 48 && mouseX < leftPos + 203
+        if (mouseX >= leftPos + 58 && mouseX < leftPos + 233
-                && mouseY >= topPos + 18 && mouseY < topPos + 141) {
+                && mouseY >= topPos + 20 && mouseY < topPos + 186) {
-            int rows = (pages().size() + 4) / 5;
+            int rows = (filteredPages().size() + 4) / 5;
-            scrollRows = Math.clamp(scrollRows - (int) Math.signum(scrollY), 0, Math.max(0, rows - 3));
+            scrollRows = Math.clamp(scrollRows - (int) Math.signum(scrollY), 0, Math.max(0, rows - 4));
             return true;
         }
         return super.mouseScrolled(mouseX, mouseY, scrollX, scrollY);
     }
+
+    private void setScrollFromMouse(double mouseY) {
+        int rows = (filteredPages().size() + 4) / 5;
+        int max = Math.max(0, rows - 4);
+        scrollRows = Math.clamp((int) Math.round((mouseY - topPos - 31.5) * max / 143.0), 0, max);
+    }
+
+    @Override public boolean mouseDragged(double mouseX, double mouseY, int button, double dragX, double dragY) {
+        if (button == 0 && pageDragSource != null) {
+            if (Math.abs(mouseX - pageDragStartX) >= 4 || Math.abs(mouseY - pageDragStartY) >= 4)
+                draggingPage = true;
+            return true;
+        }
+        if (button == 0 && draggingScrollbar) {
+            setScrollFromMouse(mouseY);
+            return true;
+        }
+        return super.mouseDragged(mouseX, mouseY, button, dragX, dragY);
+    }
+
+    @Override public boolean mouseReleased(double mouseX, double mouseY, int button) {
+        if (button == 0 && pageDragSource != null) {
+            if (draggingPage) {
+                DisplayPage target = pageAtMouse(mouseX, mouseY);
+                if (target != null && canMovePage(pageDragSource, target)
+                        && minecraft != null && minecraft.gameMode != null) {
+                    selectedCollection = target.collection();
+                    selectedPage = target.index();
+                    minecraft.gameMode.handleInventoryButtonClick(menu.containerId,
+                            WritingDeskMenu.movePageButtonId(pageDragSource.collection(), pageDragSource.index(),
+                                    target.collection(), target.index()));
+                } else if (target == null && minecraft != null && minecraft.gameMode != null) {
+                    int targetSlot = extractTargetSlot(mouseX, mouseY);
+                    minecraft.gameMode.handleInventoryButtonClick(menu.containerId,
+                            WritingDeskMenu.extractPageButtonId(pageDragSource.collection(), pageDragSource.index(),
+                                    targetSlot));
+                }
+            }
+            pageDragSource = null;
+            draggingPage = false;
+            return true;
+        }
+        if (button == 0 && draggingScrollbar) {
+            draggingScrollbar = false;
+            return true;
+        }
+        return super.mouseReleased(mouseX, mouseY, button);
+    }
+
+    @Override public boolean keyPressed(int keyCode, int scanCode, int modifiers) {
+        if (search != null && search.isFocused()) {
+            if (keyCode == 256) {
+                setFocused(null);
+                search.setFocused(false);
+            } else {
+                search.keyPressed(keyCode, scanCode, modifiers);
+            }
+            return true;
+        }
+        return super.keyPressed(keyCode, scanCode, modifiers);
+    }
 }

src/main/java/net/dnorberg/rivencraft/gametest/WritingDataGameTests.java

@@ -244,14 +244,14 @@ public final class WritingDataGameTests {
     @GameTest(template = "empty")
     public static void linkPanelPreparationConsumesOnePageAndConfiguredInkOnlyOnSuccess(GameTestHelper helper) {
         var player = helper.makeMockServerPlayerInLevel();
-        ItemStack pages = new ItemStack(ModItems.PAGE.get(), 2);
+        ItemStack pages = new ItemStack(Items.PAPER, 2);
         ItemStack vial = new ItemStack(ModItems.INK_VIAL.get());
         player.setItemInHand(InteractionHand.MAIN_HAND, vial);
         player.setItemInHand(InteractionHand.OFF_HAND, pages);
 
         helper.assertTrue(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
-                "A blank Page and sufficient ink must prepare one link panel");
+                "Paper and sufficient ink must prepare one link panel");
-        helper.assertValueEqual(pages.getCount(), 1, "Preparation must consume exactly one blank Page");
+        helper.assertValueEqual(pages.getCount(), 1, "Preparation must consume exactly one paper");
         helper.assertValueEqual(InkVialItem.remaining(player.getMainHandItem()),
                 InkVialItem.CAPACITY - WritingInkService.linkPanelCost(),
                 "Preparation must consume exactly the server-configured ink cost");
@@ -274,14 +274,14 @@ public final class WritingDataGameTests {
         ItemStack lowInk = new ItemStack(ModItems.INK_VIAL.get());
         lowInk.set(ModDataComponents.INK_REMAINING.get(), WritingInkService.linkPanelCost() - 1);
         player.setItemInHand(InteractionHand.MAIN_HAND, lowInk);
-        player.setItemInHand(InteractionHand.OFF_HAND, new ItemStack(ModItems.PAGE.get()));
+        player.setItemInHand(InteractionHand.OFF_HAND, new ItemStack(Items.PAPER));
         helper.assertFalse(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
                 "Insufficient ink must reject link-panel preparation");
         helper.assertValueEqual(InkVialItem.remaining(player.getMainHandItem()),
                 WritingInkService.linkPanelCost() - 1,
                 "Insufficient ink must remain untouched");
-        helper.assertValueEqual(PageItem.content(player.getOffhandItem()).kind(), PageContent.Kind.BLANK,
+        helper.assertTrue(player.getOffhandItem().is(Items.PAPER),
-                "Insufficient ink must leave the Page blank");
+                "Insufficient ink must leave paper untouched");
 
         lowInk.set(ModDataComponents.INK_REMAINING.get(), WritingInkService.linkPanelCost());
         helper.assertTrue(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
@@ -290,7 +290,7 @@ public final class WritingDataGameTests {
                 "A depleted Ink Vial must return a reusable glass bottle");
         helper.assertValueEqual(PageItem.content(player.getOffhandItem()).kind(),
                 PageContent.Kind.LINK_PANEL,
-                "A single blank Page must be replaced by one Link Panel Page");
+                "A single paper must be replaced by one Link Panel Page");
         helper.succeed();
     }
 
@@ -298,7 +298,7 @@ public final class WritingDataGameTests {
     public static void stackedInkVialsSplitWithoutChangingTheOtherVials(GameTestHelper helper) {
         var player = helper.makeMockServerPlayerInLevel();
         player.setItemInHand(InteractionHand.MAIN_HAND, new ItemStack(ModItems.INK_VIAL.get(), 2));
-        player.setItemInHand(InteractionHand.OFF_HAND, new ItemStack(ModItems.PAGE.get()));
+        player.setItemInHand(InteractionHand.OFF_HAND, new ItemStack(Items.PAPER));
 
         helper.assertTrue(WritingInkService.prepareLinkPanel(player, InteractionHand.MAIN_HAND),
                 "A stack of full vials must support preparing one panel");

src/main/java/net/dnorberg/rivencraft/gametest/WritingDeskGameTests.java

@@ -3,13 +3,18 @@ package net.dnorberg.rivencraft.gametest;
 import java.util.List;
 import net.dnorberg.rivencraft.Rivencraft;
 import net.dnorberg.rivencraft.block.entity.WritingDeskBlockEntity;
+import net.dnorberg.rivencraft.block.WritingDeskBlock;
 import net.dnorberg.rivencraft.menu.WritingDeskMenu;
 import net.dnorberg.rivencraft.item.PageItem;
 import net.dnorberg.rivencraft.registry.ModBlocks;
 import net.dnorberg.rivencraft.registry.ModDataComponents;
 import net.dnorberg.rivencraft.registry.ModItems;
 import net.dnorberg.rivencraft.writing.NotebookContents;
+import net.dnorberg.rivencraft.writing.SymbolReference;
+import net.dnorberg.rivencraft.writing.WritingDeskCatalog;
 import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.resources.ResourceLocation;
 import net.minecraft.gametest.framework.GameTest;
 import net.minecraft.gametest.framework.GameTestHelper;
 import net.minecraft.world.entity.item.ItemEntity;
@@ -32,7 +37,7 @@ public final class WritingDeskGameTests {
         var original = new WritingDeskBlockEntity(pos, ModBlocks.WRITING_DESK.get().defaultBlockState());
         original.setItem(0, new ItemStack(ModItems.NOTEBOOK.get()));
         original.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
-        original.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(ModItems.PAGE.get(), 12));
+        original.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER, 12));
         original.setActiveCollection(2);
         var saved = original.saveWithoutMetadata(helper.getLevel().registryAccess());
         var restored = new WritingDeskBlockEntity(pos, ModBlocks.WRITING_DESK.get().defaultBlockState());
@@ -52,14 +57,14 @@ public final class WritingDeskGameTests {
         WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
         desk.setItem(0, new ItemStack(ModItems.NOTEBOOK.get()));
         desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
-        desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(ModItems.PAGE.get(), 12));
+        desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER, 12));
         helper.getLevel().setBlock(pos, Blocks.AIR.defaultBlockState(), 3);
         var drops = helper.getLevel().getEntitiesOfClass(ItemEntity.class, new AABB(pos).inflate(2));
         int notebooks = drops.stream().filter(e -> e.getItem().is(ModItems.NOTEBOOK.get())).mapToInt(e -> e.getItem().getCount()).sum();
-        int ink = drops.stream().filter(e -> e.getItem().is(ModItems.INK_VIAL.get())).mapToInt(e -> e.getItem().getCount()).sum();
+        int bottles = drops.stream().filter(e -> e.getItem().is(Items.GLASS_BOTTLE)).mapToInt(e -> e.getItem().getCount()).sum();
-        int pages = drops.stream().filter(e -> e.getItem().is(ModItems.PAGE.get())).mapToInt(e -> e.getItem().getCount()).sum();
+        int pages = drops.stream().filter(e -> e.getItem().is(Items.PAPER)).mapToInt(e -> e.getItem().getCount()).sum();
         helper.assertValueEqual(notebooks, 1, "Notebook must drop exactly once");
-        helper.assertValueEqual(ink, 1, "Ink must drop exactly once");
+        helper.assertValueEqual(bottles, 1, "Consumed vial must return one glass bottle on break");
         helper.assertValueEqual(pages, 12, "Pages must drop without loss");
         helper.succeed();
     }
@@ -76,7 +81,7 @@ public final class WritingDeskGameTests {
         helper.assertTrue(menu.stillValid(player), "Placed desk must keep its menu valid");
         helper.assertTrue(menu.clickMenuButton(player, 3), "Active collection control must accept a valid tab");
         helper.assertValueEqual(desk.activeCollection(), 3, "Selected tab must be stored on the desk");
-        menu.quickMoveStack(player, 9);
+        menu.quickMoveStack(player, WritingDeskMenu.COPY_RESULT + 1);
         helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.PAPER).getCount(), 12, "Shift-click must deposit all pages");
         helper.assertTrue(player.getInventory().getItem(9).isEmpty(), "Shift-click must consume player source stack");
         menu.quickMoveStack(player, WritingDeskBlockEntity.PAPER);
@@ -106,12 +111,12 @@ public final class WritingDeskGameTests {
                 "A source page with paper and ink must preview one copy");
         helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.PAPER).getCount(), 2,
                 "Previewing must not consume paper");
-        helper.assertValueEqual(desk.inkRemaining(), 0, "Previewing must not consume ink");
+        helper.assertValueEqual(desk.inkRemaining(), 16, "Inserting a vial must fill the empty bar before copying");
         menu.clicked(WritingDeskMenu.COPY_RESULT, 0, ClickType.PICKUP, player);
         helper.assertTrue(menu.getCarried().is(ModItems.PAGE.get()), "Taking result must give the copied page");
         helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.PAPER).getCount(), 1,
                 "Taking a copy must consume one paper");
-        helper.assertValueEqual(desk.inkRemaining(), 15, "First copy must refill to 16 and consume one ink");
+        helper.assertValueEqual(desk.inkRemaining(), 15, "First copy must consume one ink");
         helper.assertTrue(desk.getItem(WritingDeskBlockEntity.INK).isEmpty(), "Refill must consume one vial");
         helper.assertTrue(desk.getItem(WritingDeskBlockEntity.RETURN).is(Items.GLASS_BOTTLE),
                 "Refill must return a vanilla glass bottle");
@@ -130,6 +135,48 @@ public final class WritingDeskGameTests {
         helper.succeed();
     }
 
+    @GameTest(template = "empty")
+    public static void emptyDeskInkBarRefillsWithoutCopying(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get(), 2));
+        helper.assertValueEqual(desk.inkRemaining(), 16, "Inserting a vial must refill immediately");
+        helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.INK).getCount(), 1,
+                "Refill must consume exactly one vial");
+        helper.assertTrue(desk.getItem(WritingDeskBlockEntity.RETURN).is(Items.GLASS_BOTTLE),
+                "Refill must put a vanilla glass bottle in the return slot");
+        helper.runAfterDelay(2, () -> {
+            helper.assertValueEqual(desk.inkRemaining(), 16, "Full bar must not refill again");
+            helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.INK).getCount(), 1,
+                    "Full bar must leave the second vial untouched");
+            helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.RETURN).getCount(), 1,
+                    "Full bar must not create another bottle");
+            helper.succeed();
+        });
+    }
+
+    @GameTest(template = "empty")
+    public static void emptyDeskInkBarWaitsForBottleSpace(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        desk.setItem(WritingDeskBlockEntity.RETURN, new ItemStack(Items.GLASS_BOTTLE, 64));
+        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
+        helper.assertValueEqual(desk.inkRemaining(), 0, "Full bottle slot must block automatic refill");
+        helper.assertTrue(desk.getItem(WritingDeskBlockEntity.INK).is(ModItems.INK_VIAL.get()),
+                "Blocked refill must preserve the vial");
+        helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.RETURN).getCount(), 64,
+                "Blocked refill must preserve the bottle stack");
+        desk.removeItem(WritingDeskBlockEntity.RETURN, 1);
+        helper.assertValueEqual(desk.inkRemaining(), 16, "Removing a bottle must immediately permit refill");
+        helper.assertTrue(desk.getItem(WritingDeskBlockEntity.INK).isEmpty(),
+                "Refill must consume the waiting vial");
+        helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.RETURN).getCount(), 64,
+                "Refill must return one glass bottle to the available space");
+        helper.succeed();
+    }
+
     @GameTest(template = "empty")
     public static void shiftClickCopiesOnlyWhenResourcesAndBottleSpaceExist(GameTestHelper helper) {
         BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
@@ -137,8 +184,8 @@ public final class WritingDeskGameTests {
         WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
         desk.setItem(0, PageItem.createLinkPanelPage());
         desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER, 2));
-        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
         desk.setItem(WritingDeskBlockEntity.RETURN, new ItemStack(Items.GLASS_BOTTLE, 64));
+        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
         var player = helper.makeMockServerPlayerInLevel();
         player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
         WritingDeskMenu menu = new WritingDeskMenu(1, player.getInventory(), desk);
@@ -175,7 +222,7 @@ public final class WritingDeskGameTests {
         menu.broadcastChanges();
         helper.assertTrue(menu.getSlot(WritingDeskMenu.COPY_RESULT).getItem().isEmpty(),
                 "An empty selected position must not create a copy");
-        helper.assertTrue(menu.clickMenuButton(player, 17), "Second page selection must be accepted");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.PAGE_BUTTON_BASE + 1), "Second page selection must be accepted");
         menu.broadcastChanges();
         helper.assertTrue(menu.getSlot(WritingDeskMenu.COPY_RESULT).getItem().is(ModItems.PAGE.get()),
                 "Selecting the populated page must show a copy");
@@ -206,4 +253,370 @@ public final class WritingDeskGameTests {
                 "Shared desk must spend paper only once");
         helper.succeed();
     }
+
+    @GameTest(template = "empty")
+    public static void catalogAggregatesKnownSymbolsAcrossCollections(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        ResourceLocation known = ResourceLocation.parse("rivencraft:terrain/standard");
+        ItemStack page = PageItem.createSymbolPage(new SymbolReference(known));
+        ItemStack notebook = new ItemStack(ModItems.NOTEBOOK.get());
+        notebook.set(ModDataComponents.NOTEBOOK_CONTENTS.get(), new NotebookContents(List.of(page.copy())));
+        desk.setItem(0, page);
+        desk.setItem(1, notebook);
+        helper.assertValueEqual(WritingDeskCatalog.available(desk).size(), 1,
+                "Duplicate symbols across loose pages and notebooks must appear once");
+        helper.assertValueEqual(WritingDeskCatalog.available(desk).getFirst().id(), known,
+                "Catalog must retain the authoritative symbol ID");
+        var player = helper.makeMockServerPlayerInLevel();
+        player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        WritingDeskMenu menu = new WritingDeskMenu(1, player.getInventory(), desk);
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.CATALOG_BUTTON_BASE + 1), "Out-of-range catalog index must be rejected");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.CATALOG_BUTTON_BASE), "Known catalog symbol must be selectable");
+        desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER));
+        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
+        menu.broadcastChanges();
+        helper.assertTrue(menu.getSlot(WritingDeskMenu.COPY_RESULT).getItem().is(ModItems.PAGE.get()),
+                "Catalog selection must preview a copy of the known symbol");
+        desk.setItem(0, ItemStack.EMPTY);
+        desk.setItem(1, ItemStack.EMPTY);
+        menu.broadcastChanges();
+        helper.assertTrue(menu.catalog().isEmpty(), "Removed sources must invalidate catalog for the viewer");
+        helper.assertTrue(menu.getSlot(WritingDeskMenu.COPY_RESULT).getItem().isEmpty(),
+                "Removed sources must invalidate the copy output");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void fullInventoryCannotConsumeCopyMaterials(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        desk.setItem(0, PageItem.createLinkPanelPage());
+        desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER));
+        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
+        var player = helper.makeMockServerPlayerInLevel();
+        player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        for (int i = 0; i < 36; i++) player.getInventory().setItem(i, new ItemStack(Items.COBBLESTONE, 64));
+        WritingDeskMenu menu = new WritingDeskMenu(1, player.getInventory(), desk);
+        helper.assertTrue(menu.quickMoveStack(player, WritingDeskMenu.COPY_RESULT).isEmpty(),
+                "Full inventory must reject shift-click copy");
+        helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.PAPER).getCount(), 1,
+                "Rejected copy must preserve paper");
+        helper.assertValueEqual(desk.inkRemaining(), 16, "Rejected copy must preserve the filled ink meter");
+        helper.assertTrue(desk.getItem(WritingDeskBlockEntity.INK).isEmpty(),
+                "The vial should already have refilled the empty meter");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void twoBlockDeskSharesOneInventoryAndBreaksTogether(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        var block = ModBlocks.WRITING_DESK.get();
+        var state = block.defaultBlockState().setValue(WritingDeskBlock.FACING, Direction.NORTH);
+        helper.getLevel().setBlock(pos, state, 3);
+        block.setPlacedBy(helper.getLevel(), pos, state, null, new ItemStack(block));
+        BlockPos extension = pos.relative(Direction.EAST);
+        helper.assertTrue(helper.getLevel().getBlockState(extension).is(block),
+                "Placing a desk must reserve the adjacent second block");
+        helper.assertTrue(helper.getLevel().getBlockState(extension).getValue(WritingDeskBlock.EXTENSION),
+                "Adjacent half must be marked as an extension");
+        WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        helper.assertTrue(helper.getLevel().getBlockEntity(extension) == null,
+                "Extension must not duplicate the inventory");
+        desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER, 7));
+        helper.getLevel().destroyBlock(extension, true);
+        helper.assertTrue(helper.getLevel().getBlockState(pos).isAir(),
+                "Breaking the extension must remove the controller");
+        var drops = helper.getLevel().getEntitiesOfClass(ItemEntity.class, new AABB(pos).inflate(3));
+        int desks = drops.stream().filter(e -> e.getItem().is(block.asItem()))
+                .mapToInt(e -> e.getItem().getCount()).sum();
+        int paper = drops.stream().filter(e -> e.getItem().is(Items.PAPER))
+                .mapToInt(e -> e.getItem().getCount()).sum();
+        helper.assertValueEqual(desks, 1, "Breaking either half must drop one desk");
+        helper.assertValueEqual(paper, 7, "Breaking either half must drop stored paper once");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void breakingControllerRemovesExtensionWithoutDuplicateDesk(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        var block = ModBlocks.WRITING_DESK.get();
+        var state = block.defaultBlockState().setValue(WritingDeskBlock.FACING, Direction.NORTH);
+        helper.getLevel().setBlock(pos, state, 3);
+        block.setPlacedBy(helper.getLevel(), pos, state, null, new ItemStack(block));
+        BlockPos extension = pos.relative(Direction.EAST);
+        helper.getLevel().destroyBlock(pos, true);
+        helper.assertTrue(helper.getLevel().getBlockState(extension).isAir(),
+                "Breaking the controller must remove the extension");
+        var drops = helper.getLevel().getEntitiesOfClass(ItemEntity.class, new AABB(pos).inflate(3));
+        int desks = drops.stream().filter(e -> e.getItem().is(block.asItem()))
+                .mapToInt(e -> e.getItem().getCount()).sum();
+        helper.assertValueEqual(desks, 1, "Controller break must drop exactly one desk");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void openDeskDoesNotOccludeTerrain(GameTestHelper helper) {
+        helper.assertFalse(ModBlocks.WRITING_DESK.get().defaultBlockState().canOcclude(),
+                "Open shelves must not cull terrain behind the desk");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void allPagesSelectionUsesTheRequestedPhysicalTab(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        ItemStack first = PageItem.createLinkPanelPage();
+        ItemStack second = PageItem.createSymbolPage(new SymbolReference(
+                ResourceLocation.parse("rivencraft:terrain/standard")));
+        desk.setItem(0, first);
+        ItemStack notebook = new ItemStack(ModItems.NOTEBOOK.get());
+        notebook.set(ModDataComponents.NOTEBOOK_CONTENTS.get(),
+                new NotebookContents(List.of(ItemStack.EMPTY, second)));
+        desk.setItem(1, notebook);
+        desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER));
+        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
+        var player = helper.makeMockServerPlayerInLevel();
+        player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        WritingDeskMenu menu = new WritingDeskMenu(1, player.getInventory(), desk);
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.ALL_PAGE_BUTTON_BASE + 2 * NotebookContents.MAX_PAGES),
+                "ALL view must reject empty cross-tab positions");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.ALL_PAGE_BUTTON_BASE + NotebookContents.MAX_PAGES + 1),
+                "ALL view must accept the populated second tab page");
+        helper.assertTrue(ItemStack.matches(menu.getSlot(WritingDeskMenu.COPY_RESULT).getItem(), second),
+                "Copy preview must match the physical page selected from the other tab");
+        helper.assertValueEqual(desk.activeCollection(), 0,
+                "Selecting from ALL must not silently change the active tab");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void tabGroupsCycleByFourAndProtectHiddenSlots(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        var desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        var player = helper.makeMockServerPlayerInLevel();
+        player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        var menu = new WritingDeskMenu(1, player.getInventory(), desk);
+        var otherViewer = new WritingDeskMenu(2, player.getInventory(), desk);
+        menu.clickMenuButton(player, WritingDeskMenu.PREVIOUS_TABS);
+        helper.assertValueEqual(menu.firstVisibleTab(), 0, "Previous must stop at tabs 1-4");
+        menu.clickMenuButton(player, WritingDeskMenu.NEXT_TABS);
+        helper.assertValueEqual(menu.firstVisibleTab(), 4, "Next must show tabs 5-8");
+        helper.assertValueEqual(otherViewer.firstVisibleTab(), 0, "Cycling must not move another viewer's slots");
+        helper.assertFalse(menu.getSlot(0).isActive(), "Earlier tab slots must be hidden");
+        helper.assertTrue(menu.getSlot(4).isActive(), "New group's slots must be interactive");
+        desk.setItem(0, new ItemStack(ModItems.NOTEBOOK.get()));
+        menu.clicked(0, 0, ClickType.PICKUP, player);
+        helper.assertTrue(menu.getCarried().isEmpty(), "Hidden slot clicks must not take items");
+        helper.assertTrue(menu.quickMoveStack(player, 0).isEmpty(), "Hidden shift-click must be rejected");
+        player.getInventory().setItem(9, new ItemStack(ModItems.NOTEBOOK.get()));
+        menu.quickMoveStack(player, WritingDeskMenu.COPY_RESULT + 1);
+        helper.assertTrue(desk.getItem(4).is(ModItems.NOTEBOOK.get()), "Shift-click must use the visible group");
+        for (int i = 0; i < 30; i++) menu.clickMenuButton(player, WritingDeskMenu.NEXT_TABS);
+        helper.assertValueEqual(menu.firstVisibleTab(), 84, "Last group must be tabs 85-88");
+        helper.assertTrue(menu.clickMenuButton(player, 87), "Tab 88 must be selectable without page-ID collisions");
+        helper.assertValueEqual(desk.activeCollection(), 87, "Tab 88 must become active");
+        helper.assertFalse(menu.clickMenuButton(player, 88), "Tab 89 must not exist");
+        desk.setItem(87, PageItem.createLinkPanelPage());
+        desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER));
+        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.ALL_PAGE_BUTTON_BASE + 87 * NotebookContents.MAX_PAGES),
+                "ALL must select a physical page from tab 88");
+        helper.assertTrue(menu.quickMoveStack(player, WritingDeskMenu.COPY_RESULT).is(ModItems.PAGE.get()),
+                "Tab 88's page must be copyable");
+        menu.clickMenuButton(player, WritingDeskMenu.PREVIOUS_TABS);
+        helper.assertValueEqual(menu.firstVisibleTab(), 80, "Previous must move back four tabs");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void oldDeskInventoryMigratesAndAll88TabsPersist(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        var registries = helper.getLevel().registryAccess();
+        var oldItems = net.minecraft.core.NonNullList.withSize(8, ItemStack.EMPTY);
+        oldItems.set(0, new ItemStack(ModItems.NOTEBOOK.get()));
+        oldItems.set(3, PageItem.createLinkPanelPage());
+        oldItems.set(4, new ItemStack(ModItems.INK_VIAL.get(), 2));
+        oldItems.set(5, new ItemStack(Items.GLASS_BOTTLE, 3));
+        oldItems.set(6, new ItemStack(Items.PAPER, 12));
+        oldItems.set(7, PageItem.createLinkPanelPage());
+        var oldTag = new net.minecraft.nbt.CompoundTag();
+        net.minecraft.world.ContainerHelper.saveAllItems(oldTag, oldItems, registries);
+        oldTag.putInt("InkRemaining", 7);
+        oldTag.putInt("ActiveCollection", 3);
+        var desk = new WritingDeskBlockEntity(pos, ModBlocks.WRITING_DESK.get().defaultBlockState());
+        desk.loadWithComponents(oldTag, registries);
+        for (int i = 0; i < 4; i++) {
+            helper.assertTrue(ItemStack.matches(desk.getItem(i), oldItems.get(i)), "Original tab must survive migration");
+            helper.assertTrue(ItemStack.matches(desk.getItem(WritingDeskBlockEntity.INK + i), oldItems.get(4 + i)),
+                    "Original supplies and legacy output must survive migration");
+            helper.assertTrue(desk.getItem(4 + i).isEmpty(), "Supplies must not be duplicated into new tabs");
+        }
+        helper.assertValueEqual(desk.inkRemaining(), 7, "Migration must preserve ink meter");
+        helper.assertValueEqual(desk.activeCollection(), 3, "Migration must preserve active tab");
+        for (int i = 0; i < WritingDeskBlockEntity.COLLECTIONS; i++) desk.setItem(i, PageItem.createLinkPanelPage());
+        desk.setActiveCollection(87);
+        var restored = new WritingDeskBlockEntity(pos, ModBlocks.WRITING_DESK.get().defaultBlockState());
+        restored.loadWithComponents(desk.saveWithoutMetadata(registries), registries);
+        for (int i = 0; i < WritingDeskBlockEntity.COLLECTIONS; i++)
+            helper.assertTrue(restored.getItem(i).is(ModItems.PAGE.get()), "All 88 tab contents must survive save/load");
+        helper.assertValueEqual(restored.activeCollection(), 87, "Tab 88 selection must survive save/load");
+        helper.assertValueEqual(restored.getItem(WritingDeskBlockEntity.PAPER).getCount(), 12, "Reload must not repeat migration");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void surfacePlacesCarriedPagesWithoutLossOrOverwrite(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        var desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        desk.setItem(87, new ItemStack(ModItems.NOTEBOOK.get()));
+        var player = helper.makeMockServerPlayerInLevel();
+        player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        var menu = new WritingDeskMenu(1, player.getInventory(), desk);
+        ItemStack held = PageItem.createLinkPanelPage().copyWithCount(3);
+        ItemStack expectedPage = held.copyWithCount(1);
+        player.getInventory().setItem(9, held);
+        menu.clicked(WritingDeskMenu.COPY_RESULT + 1, 0, ClickType.PICKUP, player);
+        int lastPosition = WritingDeskMenu.PLACE_PAGE_BUTTON_BASE + 87 * NotebookContents.MAX_PAGES + 26;
+        helper.assertTrue(menu.clickMenuButton(player, lastPosition), "Surface must place into final notebook position");
+        helper.assertValueEqual(menu.getCarried().getCount(), 2, "Placing must consume exactly one held page");
+        var pages = desk.getItem(87).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pages();
+        helper.assertValueEqual(pages.size(), 27, "Placement must preserve addressed position");
+        helper.assertTrue(pages.get(0).isEmpty() && pages.get(25).isEmpty(), "Placement must preserve preceding gaps");
+        helper.assertTrue(ItemStack.matches(pages.get(26), expectedPage), "Stored page must preserve components");
+        helper.assertFalse(menu.clickMenuButton(player, lastPosition), "Occupied position must not be overwritten");
+        helper.assertValueEqual(menu.getCarried().getCount(), 2, "Rejected placement must preserve cursor");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.PLACE_PAGE_BUTTON_BASE + 88 * NotebookContents.MAX_PAGES),
+                "Out-of-range placement must be rejected");
+        helper.assertValueEqual(menu.pageCapacity(87), NotebookContents.MAX_PAGES, "Notebook tab must expose normal notebook capacity");
+        helper.assertValueEqual(menu.pageCapacity(0), 0, "Empty tab has no page storage");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.PLACE_PAGE_BUTTON_BASE), "Empty tab must require a collection first");
+        desk.setItem(0, PageItem.createLinkPanelPage());
+        helper.assertValueEqual(menu.pageCapacity(0), 1, "Loose page tab must expose exactly one position");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.PLACE_PAGE_BUTTON_BASE), "Loose page must not be replaced");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.PLACE_PAGE_BUTTON_BASE + 1), "Loose page tab must not grow extra positions");
+        helper.assertValueEqual(menu.getCarried().getCount(), 2, "Rejected placements must preserve cursor");
+        helper.assertTrue(menu.clickMenuButton(player, lastPosition - 1), "A second empty notebook position must accept a page");
+        helper.assertTrue(menu.clickMenuButton(player, lastPosition - 2), "A third empty notebook position must accept the last page");
+        helper.assertTrue(menu.getCarried().isEmpty(), "Final placement must clear cursor");
+        menu.setCarried(new ItemStack(Items.DIAMOND));
+        helper.assertFalse(menu.clickMenuButton(player, lastPosition - 3), "Non-page items must be rejected");
+        helper.assertTrue(menu.getCarried().is(Items.DIAMOND), "Rejected item must remain held");
+        var restored = new WritingDeskBlockEntity(pos, ModBlocks.WRITING_DESK.get().defaultBlockState());
+        restored.loadWithComponents(desk.saveWithoutMetadata(helper.getLevel().registryAccess()), helper.getLevel().registryAccess());
+        helper.assertValueEqual(restored.getItem(87).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pageCount(), 3,
+                "Placed pages must persist in the notebook");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void deskSurfaceDragMovesAndSwapsNotebookPages(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        var desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        ItemStack linkPanel = PageItem.createLinkPanelPage();
+        ItemStack terrain = PageItem.createSymbolPage(new SymbolReference(
+                ResourceLocation.parse("rivencraft:terrain/standard")));
+        ItemStack firstBook = new ItemStack(ModItems.NOTEBOOK.get());
+        firstBook.set(ModDataComponents.NOTEBOOK_CONTENTS.get(), new NotebookContents(List.of(linkPanel, terrain)));
+        desk.setItem(0, firstBook);
+        desk.setItem(1, new ItemStack(ModItems.NOTEBOOK.get()));
+        desk.setItem(2, PageItem.createLinkPanelPage());
+        var player = helper.makeMockServerPlayerInLevel();
+        player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        var menu = new WritingDeskMenu(1, player.getInventory(), desk);
+        int moveToEmpty = WritingDeskMenu.movePageButtonId(0, 0, 0, 26);
+        helper.assertTrue(menu.clickMenuButton(player, moveToEmpty), "Drag must move to a distant empty notebook position");
+        var pages = desk.getItem(0).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pages();
+        helper.assertTrue(pages.get(0).isEmpty(), "Moving must clear the source position");
+        helper.assertTrue(ItemStack.matches(pages.get(26), linkPanel), "Moving must preserve page components");
+        helper.assertValueEqual(desk.getItem(0).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pageCount(), 2,
+                "Moving must preserve total page count");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.movePageButtonId(0, 26, 0, 1)),
+                "Drag onto an occupied position must swap pages");
+        pages = desk.getItem(0).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pages();
+        helper.assertTrue(ItemStack.matches(pages.get(1), linkPanel) && ItemStack.matches(pages.get(26), terrain),
+                "Swap must preserve both pages");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.movePageButtonId(0, 1, 1, 5)),
+                "Drag into another notebook must work");
+        var otherPages = desk.getItem(1).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pages();
+        helper.assertTrue(ItemStack.matches(otherPages.get(5), linkPanel)
+                && desk.getItem(0).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pages().get(1).isEmpty(),
+                "Cross notebook move must have one destination and no old source");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.movePageButtonId(0, 1, 1, 6)),
+                "Dragging an empty source must be rejected");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.movePageButtonId(2, 0, 1, 6)),
+                "A loose page should move into a notebook position");
+        helper.assertTrue(desk.getItem(2).isEmpty()
+                && desk.getItem(1).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pages().get(6).is(ModItems.PAGE.get()),
+                "Moving a loose page must empty its tab without losing the item");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.movePageButtonId(1, 5, 1, 5)),
+                "A no-op drag must be rejected");
+        menu.setCarried(new ItemStack(Items.DIAMOND));
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.movePageButtonId(1, 5, 1, 6)),
+                "Held inventory items must not be moved by a panel drag");
+        helper.assertTrue(ItemStack.matches(desk.getItem(1).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pages().get(5), linkPanel),
+                "Rejected drags must leave notebook data intact");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void deskSurfaceDragExtractsPagesToInventoryAndTabs(GameTestHelper helper) {
+        BlockPos pos = helper.absolutePos(new BlockPos(1, 1, 1));
+        helper.getLevel().setBlock(pos, ModBlocks.WRITING_DESK.get().defaultBlockState(), 3);
+        var desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
+        ItemStack page = PageItem.createLinkPanelPage();
+        ItemStack source = new ItemStack(ModItems.NOTEBOOK.get());
+        source.set(ModDataComponents.NOTEBOOK_CONTENTS.get(),
+                new NotebookContents(List.of(page, page, page, page, page, page)));
+        desk.setItem(0, source);
+        ItemStack otherBook = new ItemStack(ModItems.NOTEBOOK.get());
+        ItemStack terrain = PageItem.createSymbolPage(new SymbolReference(
+                ResourceLocation.parse("rivencraft:terrain/standard")));
+        otherBook.set(ModDataComponents.NOTEBOOK_CONTENTS.get(), new NotebookContents(List.of(terrain)));
+        desk.setItem(2, otherBook);
+        var player = helper.makeMockServerPlayerInLevel();
+        player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        player.getInventory().setItem(10, page.copyWithCount(2));
+        var menu = new WritingDeskMenu(1, player.getInventory(), desk);
+        int inventoryStart = WritingDeskMenu.COPY_RESULT + 1;
+
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(0, 0, -1)),
+                "Dropping away from a slot must return the page to the cursor");
+        helper.assertTrue(ItemStack.matches(menu.getCarried(), page), "Cursor must hold the original page item");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(0, 1, inventoryStart)),
+                "Extraction must not replace an occupied cursor");
+        menu.setCarried(ItemStack.EMPTY);
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(0, 1, inventoryStart)),
+                "Dropping on player inventory must transfer a page");
+        helper.assertTrue(ItemStack.matches(player.getInventory().getItem(9), page),
+                "Transferred page must retain its components");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(0, 2, 1)),
+                "Dropping on an empty tab must store a loose page");
+        helper.assertTrue(ItemStack.matches(desk.getItem(1), page), "Tab must hold the extracted page");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(0, 3, 2)),
+                "Dropping on a notebook tab must insert the page");
+        var otherPages = desk.getItem(2).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pages();
+        helper.assertTrue(ItemStack.matches(otherPages.get(0), terrain)
+                && ItemStack.matches(otherPages.get(1), page), "Notebook drop must preserve existing pages");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(0, 4, inventoryStart + 1)),
+                "Dropping on a matching inventory stack must merge one page");
+        helper.assertValueEqual(player.getInventory().getItem(10).getCount(), 3, "Merge must add exactly one page");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(0, 5, 1)),
+                "Occupied loose-page tabs must reject a drop");
+        helper.assertFalse(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(0, 5, WritingDeskBlockEntity.INK)),
+                "Ink slot must not accept an extracted page");
+        helper.assertValueEqual(desk.getItem(0).get(ModDataComponents.NOTEBOOK_CONTENTS.get()).pageCount(), 1,
+                "Rejected drops must leave the remaining source page in the notebook");
+        helper.assertTrue(menu.clickMenuButton(player, WritingDeskMenu.extractPageButtonId(1, 0, -1)),
+                "A loose page shown on the panel must be draggable back to the cursor");
+        helper.assertTrue(desk.getItem(1).isEmpty() && ItemStack.matches(menu.getCarried(), page),
+                "Extracting a loose page must empty its tab and return the same item");
+        helper.succeed();
+    }
 }

src/main/java/net/dnorberg/rivencraft/menu/WritingDeskMenu.java

@@ -7,6 +7,14 @@ import net.dnorberg.rivencraft.registry.ModItems;
 import net.dnorberg.rivencraft.registry.ModMenus;
 import net.dnorberg.rivencraft.writing.NotebookContents;
 import net.dnorberg.rivencraft.writing.PageContent;
+import net.dnorberg.rivencraft.writing.SymbolCatalog;
+import net.dnorberg.rivencraft.writing.SymbolDisplayMetadata;
+import net.dnorberg.rivencraft.writing.SymbolReference;
+import net.dnorberg.rivencraft.writing.WritingDeskCatalog;
+import net.dnorberg.rivencraft.network.WritingDeskCatalogPayload;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.level.ServerPlayer;
+import net.neoforged.neoforge.network.PacketDistributor;
 import java.util.List;
 import net.minecraft.network.RegistryFriendlyByteBuf;
 import net.minecraft.world.Container;
@@ -21,18 +29,35 @@ import net.minecraft.world.item.Items;
 
 public final class WritingDeskMenu extends AbstractContainerMenu {
     public static final int COPY_RESULT = WritingDeskBlockEntity.SIZE;
+    public static final int VISIBLE_TABS = 4;
+    public static final int PREVIOUS_TABS = 90;
+    public static final int NEXT_TABS = 91;
+    public static final int PAGE_BUTTON_BASE = 128;
+    public static final int CATALOG_BUTTON_BASE = 512;
+    public static final int ALL_PAGE_BUTTON_BASE = 32768;
+    public static final int PLACE_PAGE_BUTTON_BASE = 65536;
+    private static final int PAGE_ADDRESS_COUNT = WritingDeskBlockEntity.COLLECTIONS * NotebookContents.MAX_PAGES;
+    public static final int MOVE_PAGE_BUTTON_BASE = PLACE_PAGE_BUTTON_BASE + PAGE_ADDRESS_COUNT;
     private static final int PLAYER_START = COPY_RESULT + 1;
+    private static final int EXTRACT_TARGET_COUNT = PLAYER_START + 36 + 1;
+    public static final int EXTRACT_PAGE_BUTTON_BASE = MOVE_PAGE_BUTTON_BASE + PAGE_ADDRESS_COUNT * PAGE_ADDRESS_COUNT;
     private final Container desk;
     private final WritingDeskBlockEntity blockEntity;
     private final SimpleContainer result = new SimpleContainer(1);
     private final boolean clientSide;
     private int syncedActiveCollection;
     private int syncedInkRemaining;
+    private int firstVisibleTab;
     private int selectedPage;
+    private int selectedCollection = -1;
+    private ResourceLocation selectedSymbol;
+    private List<SymbolDisplayMetadata> catalog = List.of();
+    private final ServerPlayer serverViewer;
 
     public WritingDeskMenu(int id, Inventory inventory, RegistryFriendlyByteBuf data) {
         this(id, inventory, inventory.player.level().getBlockEntity(data.readBlockPos())
                 instanceof WritingDeskBlockEntity found ? found : null);
+        catalog = WritingDeskCatalog.read(data);
     }
 
     public WritingDeskMenu(int id, Inventory inventory, WritingDeskBlockEntity blockEntity) {
@@ -40,6 +65,13 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
         this.blockEntity = blockEntity;
         this.desk = blockEntity == null ? new SimpleContainer(WritingDeskBlockEntity.SIZE) : blockEntity;
         this.clientSide = inventory.player.level().isClientSide;
+        this.serverViewer = inventory.player instanceof ServerPlayer serverPlayer ? serverPlayer : null;
+        if (blockEntity != null && !clientSide) catalog = WritingDeskCatalog.available(blockEntity);
+        firstVisibleTab = blockEntity == null ? 0 : blockEntity.activeCollection() / VISIBLE_TABS * VISIBLE_TABS;
+        addDataSlot(new DataSlot() {
+            @Override public int get() { return firstVisibleTab; }
+            @Override public void set(int value) { firstVisibleTab = value; }
+        });
         addDataSlot(new DataSlot() {
             @Override public int get() { return WritingDeskMenu.this.blockEntity == null
                     ? syncedActiveCollection : WritingDeskMenu.this.blockEntity.activeCollection(); }
@@ -51,38 +83,226 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
             @Override public void set(int value) { syncedInkRemaining = value; }
         });
         for (int i = 0; i < WritingDeskBlockEntity.COLLECTIONS; i++) {
-            addSlot(new DeskSlot(desk, i, 12, 20 + i * 37, 1));
+            addSlot(new DeskSlot(desk, i, 37, 34 + (i % VISIBLE_TABS) * 37, 1));
         }
-        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.INK, 370, 20, 16));
+        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.INK, 385, 28, 16));
-        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.RETURN, 370, 57, 64));
+        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.RETURN, 385, 80, 64));
-        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.PAPER, 228, 20, 64));
+        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.PAPER, 241, 28, 64));
         addSlot(new DeskSlot(desk, WritingDeskBlockEntity.LEGACY_OUTPUT, -1000, -1000, 64));
-        addSlot(new CopySlot(result, 0, 228, 57));
+        addSlot(new CopySlot(result, 0, 241, 80));
         for (int row = 0; row < 3; row++) {
             for (int column = 0; column < 9; column++) {
-                addSlot(new Slot(inventory, column + row * 9 + 9, 224 + column * 18, 91 + row * 18));
+                addSlot(new Slot(inventory, column + row * 9 + 9, 241 + column * 18, 104 + row * 18));
             }
         }
         for (int column = 0; column < 9; column++) {
-            addSlot(new Slot(inventory, column, 224 + column * 18, 149));
+            addSlot(new Slot(inventory, column, 241 + column * 18, 162));
         }
     }
 
     public int activeCollection() { return syncedActiveCollection; }
+    public int firstVisibleTab() { return firstVisibleTab; }
     public int inkRemaining() { return syncedInkRemaining; }
+    public int pageCapacity(int collectionIndex) {
+        if (collectionIndex < 0 || collectionIndex >= WritingDeskBlockEntity.COLLECTIONS) return 0;
+        ItemStack collection = desk.getItem(collectionIndex);
+        return collection.is(ModItems.NOTEBOOK.get()) ? NotebookContents.MAX_PAGES
+                : collection.is(ModItems.PAGE.get()) ? 1 : 0;
+    }
+    public List<SymbolDisplayMetadata> catalog() { return catalog; }
+    public void setCatalog(List<SymbolDisplayMetadata> symbols) { catalog = List.copyOf(symbols); }
+
+    public static int movePageButtonId(int sourceCollection, int sourcePage, int targetCollection, int targetPage) {
+        int source = sourceCollection * NotebookContents.MAX_PAGES + sourcePage;
+        int target = targetCollection * NotebookContents.MAX_PAGES + targetPage;
+        return MOVE_PAGE_BUTTON_BASE + source * PAGE_ADDRESS_COUNT + target;
+    }
+
+    /** targetSlot is -1 for the cursor, otherwise a visible player or desk-tab slot. */
+    public static int extractPageButtonId(int sourceCollection, int sourcePage, int targetSlot) {
+        int source = sourceCollection * NotebookContents.MAX_PAGES + sourcePage;
+        return EXTRACT_PAGE_BUTTON_BASE + source * EXTRACT_TARGET_COUNT + targetSlot + 1;
+    }
 
     @Override public boolean clickMenuButton(Player player, int id) {
         if (blockEntity == null || !stillValid(player)) return false;
-        if (id >= 0 && id < WritingDeskBlockEntity.COLLECTIONS) {
+        if (id == PREVIOUS_TABS || id == NEXT_TABS) {
+            firstVisibleTab = Math.clamp(firstVisibleTab + (id == NEXT_TABS ? VISIBLE_TABS : -VISIBLE_TABS),
+                    0, WritingDeskBlockEntity.COLLECTIONS - VISIBLE_TABS);
+            return true;
+        } else if (id >= 0 && id < WritingDeskBlockEntity.COLLECTIONS) {
+            if (id < firstVisibleTab || id >= firstVisibleTab + VISIBLE_TABS) return false;
             blockEntity.setActiveCollection(id);
             selectedPage = 0;
-        } else if (id >= 16 && id < 16 + NotebookContents.MAX_PAGES) {
+            selectedCollection = -1;
-            selectedPage = id - 16;
+            selectedSymbol = null;
+        } else if (id >= EXTRACT_PAGE_BUTTON_BASE
+                && id < EXTRACT_PAGE_BUTTON_BASE + PAGE_ADDRESS_COUNT * EXTRACT_TARGET_COUNT) {
+            int offset = id - EXTRACT_PAGE_BUTTON_BASE;
+            int source = offset / EXTRACT_TARGET_COUNT;
+            int targetSlot = offset % EXTRACT_TARGET_COUNT - 1;
+            if (!extractPage(source / NotebookContents.MAX_PAGES, source % NotebookContents.MAX_PAGES,
+                    targetSlot)) return false;
+        } else if (id >= MOVE_PAGE_BUTTON_BASE && id < MOVE_PAGE_BUTTON_BASE + PAGE_ADDRESS_COUNT * PAGE_ADDRESS_COUNT) {
+            int offset = id - MOVE_PAGE_BUTTON_BASE;
+            int source = offset / PAGE_ADDRESS_COUNT;
+            int target = offset % PAGE_ADDRESS_COUNT;
+            if (!movePage(source / NotebookContents.MAX_PAGES, source % NotebookContents.MAX_PAGES,
+                    target / NotebookContents.MAX_PAGES, target % NotebookContents.MAX_PAGES)) return false;
+        } else if (id >= PLACE_PAGE_BUTTON_BASE
+                && id < PLACE_PAGE_BUTTON_BASE + WritingDeskBlockEntity.COLLECTIONS * NotebookContents.MAX_PAGES) {
+            int offset = id - PLACE_PAGE_BUTTON_BASE;
+            if (!placeCarriedPage(offset / NotebookContents.MAX_PAGES, offset % NotebookContents.MAX_PAGES)) return false;
+        } else if (id >= PAGE_BUTTON_BASE && id < PAGE_BUTTON_BASE + NotebookContents.MAX_PAGES) {
+            selectedPage = id - PAGE_BUTTON_BASE;
+            selectedCollection = -1;
+            selectedSymbol = null;
+        } else if (id >= ALL_PAGE_BUTTON_BASE && id < ALL_PAGE_BUTTON_BASE + WritingDeskBlockEntity.COLLECTIONS * NotebookContents.MAX_PAGES) {
+            int offset = id - ALL_PAGE_BUTTON_BASE;
+            int collection = offset / NotebookContents.MAX_PAGES;
+            int page = offset % NotebookContents.MAX_PAGES;
+            if (pageAt(collection, page).isEmpty()) return false;
+            selectedCollection = collection;
+            selectedPage = page;
+            selectedSymbol = null;
+        } else if (id >= CATALOG_BUTTON_BASE && id < CATALOG_BUTTON_BASE + catalog.size()) {
+            if (!catalog.equals(WritingDeskCatalog.available(blockEntity))) {
+                refreshCatalog();
+                return false;
+            }
+            ResourceLocation requested = catalog.get(id - CATALOG_BUTTON_BASE).id();
+            if (!WritingDeskCatalog.available(blockEntity).stream().anyMatch(entry -> entry.id().equals(requested))) {
+                return false;
+            }
+            selectedSymbol = requested;
         } else return false;
         refreshOutput();
         return true;
     }
 
+    private boolean placeCarriedPage(int collectionIndex, int pageIndex) {
+        // Resolve the actual storage position on the server, never a filtered list index.
+        ItemStack carried = getCarried();
+        if (clientSide || !carried.is(ModItems.PAGE.get())) return false;
+        ItemStack collection = desk.getItem(collectionIndex);
+        if (collection.is(ModItems.NOTEBOOK.get())) {
+            var pages = new java.util.ArrayList<>(collection.getOrDefault(
+                    ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages());
+            while (pages.size() <= pageIndex) pages.add(ItemStack.EMPTY);
+            if (!pages.get(pageIndex).isEmpty()) return false;
+            pages.set(pageIndex, carried.copyWithCount(1));
+            ItemStack updated = collection.copy();
+            updated.set(ModDataComponents.NOTEBOOK_CONTENTS.get(), new NotebookContents(pages));
+            desk.setItem(collectionIndex, updated);
+        } else return false;
+        carried.shrink(1);
+        setCarried(carried.isEmpty() ? ItemStack.EMPTY : carried);
+        selectedCollection = collectionIndex;
+        selectedPage = pageIndex;
+        selectedSymbol = null;
+        refreshCatalog();
+        broadcastChanges();
+        return true;
+    }
+
+    private boolean movePage(int sourceCollection, int sourcePage, int targetCollection, int targetPage) {
+        if (!getCarried().isEmpty() || sourceCollection == targetCollection && sourcePage == targetPage) return false;
+        ItemStack sourceBook = desk.getItem(sourceCollection);
+        ItemStack targetBook = desk.getItem(targetCollection);
+        boolean sourceNotebook = sourceBook.is(ModItems.NOTEBOOK.get());
+        boolean targetNotebook = targetBook.is(ModItems.NOTEBOOK.get());
+        if ((!sourceNotebook && (!sourceBook.is(ModItems.PAGE.get()) || sourcePage != 0))
+                || (!targetNotebook && (!targetBook.is(ModItems.PAGE.get()) || targetPage != 0))) return false;
+        var sourcePages = sourceNotebook ? new java.util.ArrayList<>(sourceBook.getOrDefault(
+                ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages()) : null;
+        if (sourceNotebook && (sourcePage >= sourcePages.size() || sourcePages.get(sourcePage).isEmpty())) return false;
+        ItemStack moving = sourceNotebook ? sourcePages.get(sourcePage) : sourceBook;
+        if (moving.getCount() != 1) return false;
+        if (!targetNotebook && targetBook.getCount() != 1) return false;
+        var targetPages = targetNotebook ? sourceCollection == targetCollection ? sourcePages
+                : new java.util.ArrayList<>(targetBook.getOrDefault(
+                        ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages()) : null;
+        if (targetNotebook) while (targetPages.size() <= targetPage) targetPages.add(ItemStack.EMPTY);
+        ItemStack displaced = targetNotebook ? targetPages.get(targetPage) : targetBook;
+        if (targetNotebook) targetPages.set(targetPage, moving);
+        if (sourceNotebook) {
+            sourcePages.set(sourcePage, displaced);
+            ItemStack updatedSource = sourceBook.copy();
+            updatedSource.set(ModDataComponents.NOTEBOOK_CONTENTS.get(), new NotebookContents(sourcePages));
+            desk.setItem(sourceCollection, updatedSource);
+        } else desk.setItem(sourceCollection, displaced.isEmpty() ? ItemStack.EMPTY : displaced.copyWithCount(1));
+        if (targetNotebook && sourceCollection != targetCollection) {
+            ItemStack updatedTarget = targetBook.copy();
+            updatedTarget.set(ModDataComponents.NOTEBOOK_CONTENTS.get(), new NotebookContents(targetPages));
+            desk.setItem(targetCollection, updatedTarget);
+        } else if (!targetNotebook) desk.setItem(targetCollection, moving.copyWithCount(1));
+        selectedCollection = targetCollection;
+        selectedPage = targetPage;
+        selectedSymbol = null;
+        refreshCatalog();
+        broadcastChanges();
+        return true;
+    }
+
+    private boolean extractPage(int sourceCollection, int sourcePage, int targetSlot) {
+        if (!getCarried().isEmpty() || targetSlot < -1 || targetSlot >= slots.size()) return false;
+        ItemStack sourceBook = desk.getItem(sourceCollection);
+        boolean sourceNotebook = sourceBook.is(ModItems.NOTEBOOK.get());
+        if (!sourceNotebook && (!sourceBook.is(ModItems.PAGE.get()) || sourcePage != 0)) return false;
+        var sourcePages = sourceNotebook ? new java.util.ArrayList<>(sourceBook.getOrDefault(
+                ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages()) : null;
+        if (sourceNotebook && (sourcePage >= sourcePages.size() || sourcePages.get(sourcePage).isEmpty())) return false;
+        ItemStack moving = sourceNotebook ? sourcePages.get(sourcePage).copyWithCount(1) : sourceBook.copyWithCount(1);
+        if (!sourceNotebook && sourceBook.getCount() != 1) return false;
+
+        if (targetSlot == -1) {
+            setCarried(moving);
+        } else {
+            if (targetSlot >= WritingDeskBlockEntity.COLLECTIONS && targetSlot < PLAYER_START) return false;
+            Slot target = slots.get(targetSlot);
+            if (!target.isActive() || !target.mayPlace(moving)) return false;
+            ItemStack current = target.getItem();
+            if (targetSlot < WritingDeskBlockEntity.COLLECTIONS && current.is(ModItems.NOTEBOOK.get())) {
+                var targetPages = targetSlot == sourceCollection ? sourcePages
+                        : new java.util.ArrayList<>(current.getOrDefault(
+                                ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages());
+                int position = -1;
+                for (int i = 0; i < NotebookContents.MAX_PAGES; i++) {
+                    if (i >= targetPages.size() || targetPages.get(i).isEmpty()) {
+                        position = i;
+                        break;
+                    }
+                }
+                if (position < 0) return false;
+                while (targetPages.size() <= position) targetPages.add(ItemStack.EMPTY);
+                targetPages.set(position, moving);
+                if (targetSlot != sourceCollection) {
+                    ItemStack updatedTarget = current.copy();
+                    updatedTarget.set(ModDataComponents.NOTEBOOK_CONTENTS.get(), new NotebookContents(targetPages));
+                    target.setByPlayer(updatedTarget);
+                }
+            } else if (current.isEmpty()) {
+                target.setByPlayer(moving);
+            } else if (targetSlot >= PLAYER_START && ItemStack.isSameItemSameComponents(current, moving)
+                    && current.getCount() < target.getMaxStackSize(moving)) {
+                target.setByPlayer(current.copyWithCount(current.getCount() + 1));
+            } else return false;
+        }
+
+        if (sourceNotebook) {
+            sourcePages.set(sourcePage, ItemStack.EMPTY);
+            ItemStack updatedSource = sourceBook.copy();
+            updatedSource.set(ModDataComponents.NOTEBOOK_CONTENTS.get(), new NotebookContents(sourcePages));
+            desk.setItem(sourceCollection, updatedSource);
+        } else desk.setItem(sourceCollection, ItemStack.EMPTY);
+        selectedCollection = sourceCollection;
+        selectedPage = sourcePage;
+        selectedSymbol = null;
+        refreshCatalog();
+        broadcastChanges();
+        return true;
+    }
+
     @Override public boolean stillValid(Player player) {
         return blockEntity != null && blockEntity.stillValid(player);
     }
@@ -102,6 +322,7 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
             return copy;
         }
         Slot slot = slots.get(index);
+        if (!slot.isActive()) return ItemStack.EMPTY;
         if (!slot.hasItem()) return ItemStack.EMPTY;
         ItemStack moving = slot.getItem();
         ItemStack original = moving.copy();
@@ -116,23 +337,39 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
     }
 
     private boolean moveIntoDesk(ItemStack moving) {
-        if (moving.is(ModItems.INK_VIAL.get())) return moveItemStackTo(moving, 4, 5, false);
+        if (moving.is(ModItems.INK_VIAL.get())) return moveItemStackTo(moving,
-        if (moving.is(ModItems.NOTEBOOK.get())) return moveItemStackTo(moving, 0, 4, false);
+                WritingDeskBlockEntity.INK, WritingDeskBlockEntity.INK + 1, false);
-        if (moving.is(Items.PAPER) || moving.is(ModItems.PAGE.get())
+        if (moving.is(ModItems.NOTEBOOK.get())) return moveItemStackTo(moving, firstVisibleTab, firstVisibleTab + VISIBLE_TABS, false);
-                && PageItem.content(moving).kind() == PageContent.Kind.BLANK)
+        if (moving.is(Items.PAPER))
             return moveItemStackTo(moving, WritingDeskBlockEntity.PAPER,
                     WritingDeskBlockEntity.PAPER + 1, false);
-        if (moving.is(ModItems.PAGE.get())) return moveItemStackTo(moving, 0, 4, false);
+        if (moving.is(ModItems.PAGE.get())) return moveItemStackTo(moving, firstVisibleTab, firstVisibleTab + VISIBLE_TABS, false);
         return false;
     }
 
     private ItemStack selectedSource() {
-        ItemStack collection = desk.getItem(blockEntity == null ? syncedActiveCollection : blockEntity.activeCollection());
+        if (selectedSymbol != null) {
-        if (collection.is(ModItems.PAGE.get())) return selectedPage == 0 ? collection : ItemStack.EMPTY;
+            SymbolReference reference = new SymbolReference(selectedSymbol);
+            return SymbolCatalog.isKnown(reference)
+                    && blockEntity != null
+                    && WritingDeskCatalog.available(blockEntity).stream()
+                    .anyMatch(entry -> entry.id().equals(selectedSymbol))
+                    ? PageItem.createSymbolPage(reference) : ItemStack.EMPTY;
+        }
+        int collectionIndex = selectedCollection >= 0 ? selectedCollection
+                : blockEntity == null ? syncedActiveCollection : blockEntity.activeCollection();
+        return pageAt(collectionIndex, selectedPage);
+    }
+
+    private ItemStack pageAt(int collectionIndex, int pageIndex) {
+        if (collectionIndex < 0 || collectionIndex >= WritingDeskBlockEntity.COLLECTIONS
+                || pageIndex < 0 || pageIndex >= NotebookContents.MAX_PAGES) return ItemStack.EMPTY;
+        ItemStack collection = desk.getItem(collectionIndex);
+        if (collection.is(ModItems.PAGE.get())) return pageIndex == 0 ? collection : ItemStack.EMPTY;
         if (collection.is(ModItems.NOTEBOOK.get())) {
             List<ItemStack> pages = collection.getOrDefault(
                     ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages();
-            return selectedPage < pages.size() ? pages.get(selectedPage) : ItemStack.EMPTY;
+            return pageIndex < pages.size() ? pages.get(pageIndex) : ItemStack.EMPTY;
         }
         return ItemStack.EMPTY;
     }
@@ -146,11 +383,24 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
 
     private void refreshOutput() {
         if (clientSide) return;
+        if (blockEntity != null) blockEntity.setDisplayPage(selectedSource());
         ItemStack preview = canCopy() ? selectedSource().copyWithCount(1) : ItemStack.EMPTY;
         if (!ItemStack.matches(result.getItem(0), preview)) result.setItem(0, preview);
     }
 
+    private void refreshCatalog() {
+        if (clientSide || blockEntity == null) return;
+        List<SymbolDisplayMetadata> current = WritingDeskCatalog.available(blockEntity);
+        if (!current.equals(catalog)) {
+            catalog = current;
+            if (serverViewer != null && serverViewer.containerMenu == this) {
+                PacketDistributor.sendToPlayer(serverViewer, new WritingDeskCatalogPayload(containerId, catalog));
+            }
+        }
+    }
+
     @Override public void broadcastChanges() {
+        refreshCatalog();
         refreshOutput();
         super.broadcastChanges();
     }
@@ -161,7 +411,9 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
             player.closeContainer();
             return;
         }
+        refreshCatalog();
         refreshOutput();
+        if (slotId >= 0 && slotId < slots.size() && !slots.get(slotId).isActive()) return;
         super.clicked(slotId, button, clickType, player);
     }
 
@@ -177,13 +429,19 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
         }
     }
 
-    private static final class DeskSlot extends Slot {
+    private final class DeskSlot extends Slot {
         private final int limit;
         private DeskSlot(Container container, int index, int x, int y, int limit) {
             super(container, index, x, y);
             this.limit = limit;
         }
-        @Override public boolean mayPlace(ItemStack stack) { return container.canPlaceItem(getContainerSlot(), stack); }
+        @Override public boolean isActive() {
+            int slot = getContainerSlot();
+            return slot >= WritingDeskBlockEntity.COLLECTIONS
+                    || slot >= firstVisibleTab && slot < firstVisibleTab + VISIBLE_TABS;
+        }
+        @Override public boolean mayPickup(Player player) { return isActive(); }
+        @Override public boolean mayPlace(ItemStack stack) { return isActive() && container.canPlaceItem(getContainerSlot(), stack); }
         @Override public int getMaxStackSize() { return limit; }
     }
 }

src/main/java/net/dnorberg/rivencraft/network/ModNetworking.java

@@ -9,6 +9,7 @@ import net.dnorberg.rivencraft.block.entity.BookStandBlockEntity;
 import net.dnorberg.rivencraft.client.ClientLinkPreviewHandler;
 import net.dnorberg.rivencraft.client.ClientBookInteractionHandler;
 import net.dnorberg.rivencraft.client.ClientAgeCelestialAngles;
+import net.dnorberg.rivencraft.client.ClientWritingDeskCatalog;
 import net.dnorberg.rivencraft.event.AgeCelestialAngleSync;
 import net.dnorberg.rivencraft.item.DescriptiveBookItem;
 import net.dnorberg.rivencraft.item.LinkingBookItem;
@@ -48,7 +49,7 @@ public final class ModNetworking {
     }
 
     public static void register(RegisterPayloadHandlersEvent event) {
-        PayloadRegistrar registrar = event.registrar("10");
+        PayloadRegistrar registrar = event.registrar("11");
         registrar.playToServer(RequestDescriptiveBookScreenPayload.TYPE, RequestDescriptiveBookScreenPayload.STREAM_CODEC,
                 ModNetworking::requestDescriptiveBookScreen);
         registrar.playToClient(OpenDescriptiveBookScreenPayload.TYPE, OpenDescriptiveBookScreenPayload.STREAM_CODEC,
@@ -68,6 +69,8 @@ public final class ModNetworking {
                 ClientLinkPreviewHandler::handle);
         registrar.playToClient(AgeCelestialAnglePayload.TYPE, AgeCelestialAnglePayload.STREAM_CODEC,
                 ClientAgeCelestialAngles::handle);
+        registrar.playToClient(WritingDeskCatalogPayload.TYPE, WritingDeskCatalogPayload.STREAM_CODEC,
+                ClientWritingDeskCatalog::handle);
     }
 
     private static void requestDescriptiveBookScreen(RequestDescriptiveBookScreenPayload payload, IPayloadContext context) {

src/main/java/net/dnorberg/rivencraft/network/WritingDeskCatalogPayload.java

@@ -0,0 +1,26 @@
+package net.dnorberg.rivencraft.network;
+
+import java.util.List;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.writing.SymbolDisplayMetadata;
+import net.dnorberg.rivencraft.writing.WritingDeskCatalog;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.ResourceLocation;
+
+/** Current server-approved symbols from this open Writing Desk menu. */
+public record WritingDeskCatalogPayload(int containerId, List<SymbolDisplayMetadata> symbols)
+        implements CustomPacketPayload {
+    public static final Type<WritingDeskCatalogPayload> TYPE = new Type<>(
+            ResourceLocation.fromNamespaceAndPath(Rivencraft.MOD_ID, "writing_desk_catalog"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, WritingDeskCatalogPayload> STREAM_CODEC =
+            StreamCodec.of(
+                    (buffer, payload) -> {
+                        buffer.writeVarInt(payload.containerId());
+                        WritingDeskCatalog.write(buffer, payload.symbols());
+                    },
+                    buffer -> new WritingDeskCatalogPayload(buffer.readVarInt(), WritingDeskCatalog.read(buffer)));
+
+    @Override public Type<? extends CustomPacketPayload> type() { return TYPE; }
+}

src/main/java/net/dnorberg/rivencraft/registry/ModBlocks.java

@@ -19,7 +19,7 @@ public final class ModBlocks {
     );
     public static final DeferredBlock<WritingDeskBlock> WRITING_DESK = BLOCKS.registerBlock(
             "writing_desk", WritingDeskBlock::new,
-            BlockBehaviour.Properties.ofFullCopy(Blocks.CRAFTING_TABLE)
+            BlockBehaviour.Properties.ofFullCopy(Blocks.CRAFTING_TABLE).noOcclusion()
     );
 
     private ModBlocks() {

src/main/java/net/dnorberg/rivencraft/registry/ModCreativeTabs.java

@@ -31,7 +31,6 @@ public final class ModCreativeTabs {
                     .title(Component.translatable("itemGroup.rivencraft.pages"))
                     .icon(PageItem::createLinkPanelPage)
                     .displayItems((parameters, output) -> {
-                        output.accept(ModItems.PAGE.get());
                         output.accept(PageItem.createLinkPanelPage());
                     })
                     .build());

src/main/java/net/dnorberg/rivencraft/writing/WritingDeskCatalog.java

@@ -0,0 +1,63 @@
+package net.dnorberg.rivencraft.writing;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+import net.dnorberg.rivencraft.block.entity.WritingDeskBlockEntity;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.dnorberg.rivencraft.registry.ModDataComponents;
+import net.dnorberg.rivencraft.registry.ModItems;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.item.ItemStack;
+
+/** A bounded, server-derived view of symbols physically present in the desk. */
+public final class WritingDeskCatalog {
+    private static final int MAX_ENTRIES = WritingDeskBlockEntity.COLLECTIONS * NotebookContents.MAX_PAGES;
+
+    private WritingDeskCatalog() {}
+
+    public static List<SymbolDisplayMetadata> available(WritingDeskBlockEntity desk) {
+        Map<ResourceLocation, SymbolDisplayMetadata> unique = new TreeMap<>();
+        for (int slot = 0; slot < WritingDeskBlockEntity.COLLECTIONS; slot++) {
+            ItemStack collection = desk.getItem(slot);
+            if (collection.is(ModItems.PAGE.get())) add(unique, collection);
+            if (collection.is(ModItems.NOTEBOOK.get())) {
+                List<ItemStack> pages = collection.getOrDefault(
+                        ModDataComponents.NOTEBOOK_CONTENTS.get(), NotebookContents.EMPTY).pages();
+                pages.forEach(page -> add(unique, page));
+            }
+        }
+        return unique.values().stream()
+                .sorted(Comparator.comparing((SymbolDisplayMetadata symbol) -> symbol.category().toString())
+                        .thenComparing(symbol -> symbol.id().toString()))
+                .toList();
+    }
+
+    private static void add(Map<ResourceLocation, SymbolDisplayMetadata> unique, ItemStack page) {
+        if (!page.is(ModItems.PAGE.get())) return;
+        PageContent content = PageItem.content(page).resolve();
+        if (content.kind() != PageContent.Kind.SYMBOL) return;
+        SymbolReference reference = content.symbol().orElseThrow();
+        SymbolCatalog.find(reference).ifPresent(definition ->
+                unique.put(reference.id(), definition.display(reference.id())));
+    }
+
+    public static void write(RegistryFriendlyByteBuf buffer, List<SymbolDisplayMetadata> entries) {
+        if (entries.size() > MAX_ENTRIES) throw new IllegalArgumentException("Desk symbol catalog exceeds limit");
+        buffer.writeVarInt(entries.size());
+        entries.forEach(entry -> SymbolDisplayMetadata.STREAM_CODEC.encode(buffer, entry));
+    }
+
+    public static List<SymbolDisplayMetadata> read(RegistryFriendlyByteBuf buffer) {
+        int count = buffer.readVarInt();
+        if (count < 0 || count > MAX_ENTRIES) throw new IllegalArgumentException("Invalid desk symbol count " + count);
+        List<SymbolDisplayMetadata> entries = new ArrayList<>(count);
+        for (int index = 0; index < count; index++) {
+            entries.add(SymbolDisplayMetadata.STREAM_CODEC.decode(buffer));
+        }
+        return List.copyOf(entries);
+    }
+}

src/main/java/net/dnorberg/rivencraft/writing/WritingInkService.java

@@ -29,7 +29,7 @@ public final class WritingInkService {
         int remaining = InkVialItem.remaining(vial);
         return vial.is(ModItems.INK_VIAL.get()) && remaining >= linkPanelCost()
                 && remaining <= InkVialItem.CAPACITY
-                && page.is(ModItems.PAGE.get()) && PageItem.content(page).kind() == PageContent.Kind.BLANK;
+                && page.is(Items.PAPER);
     }
 
     public static boolean prepareLinkPanel(Player player, InteractionHand vialHand) {

src/main/resources/assets/rivencraft/blockstates/writing_desk.json

@@ -1,8 +1,12 @@
 {
   "variants": {
-    "facing=north": { "model": "rivencraft:block/writing_desk" },
+    "facing=north,extension=false": {"model":"rivencraft:block/writing_desk"},
-    "facing=east": { "model": "rivencraft:block/writing_desk", "y": 90 },
+    "facing=east,extension=false": {"model":"rivencraft:block/writing_desk","y":90},
-    "facing=south": { "model": "rivencraft:block/writing_desk", "y": 180 },
+    "facing=south,extension=false": {"model":"rivencraft:block/writing_desk","y":180},
-    "facing=west": { "model": "rivencraft:block/writing_desk", "y": 270 }
+    "facing=west,extension=false": {"model":"rivencraft:block/writing_desk","y":270},
+    "facing=north,extension=true": {"model":"rivencraft:block/writing_desk_extension"},
+    "facing=east,extension=true": {"model":"rivencraft:block/writing_desk_extension","y":90},
+    "facing=south,extension=true": {"model":"rivencraft:block/writing_desk_extension","y":180},
+    "facing=west,extension=true": {"model":"rivencraft:block/writing_desk_extension","y":270}
   }
 }

src/main/resources/assets/rivencraft/lang/en_us.json

@@ -19,8 +19,10 @@
   "block.rivencraft.writing_desk": "Writing Desk",
   "container.rivencraft.writing_desk": "Writing Desk",
   "screen.rivencraft.writing_desk.ink": "Ink: %s/%s",
+  "screen.rivencraft.writing_desk.search": "Search",
+  "screen.rivencraft.writing_desk.no_symbols": "No available symbols",
   "item.rivencraft.ink_vial.remaining": "Ink: %s/%s",
-  "item.rivencraft.ink_vial.usage": "Use with a blank Page in the other hand to prepare a Link Panel.",
+  "item.rivencraft.ink_vial.usage": "Use with paper in the other hand to prepare a Link Panel.",
   "screen.rivencraft.notebook.search": "Search pages",
   "screen.rivencraft.notebook.move_previous": "Move selected page left",
   "screen.rivencraft.notebook.move_next": "Move selected page right",

src/main/resources/assets/rivencraft/models/block/writing_desk.json

@@ -1,8 +1,11 @@
 {
-  "parent": "minecraft:block/cube_bottom_top",
+  "parent": "minecraft:block/block",
-  "textures": {
+  "textures": {"wood":"rivencraft:block/writing_desk_wood","inlay":"rivencraft:block/writing_desk_inlay","particle":"rivencraft:block/writing_desk_wood"},
-    "top": "rivencraft:item/writing_desk",
+  "elements": [
-    "side": "minecraft:block/oak_planks",
+    {"from":[0,0,1],"to":[16,1,15],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}},
-    "bottom": "minecraft:block/oak_planks"
+    {"from":[0,8,0],"to":[16,9,16],"faces":{"up":{"texture":"#inlay"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}},
-  }
+    {"from":[0,0,1],"to":[1,8,15],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}},
+    {"from":[1,3,1],"to":[16,4,15],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}},
+    {"from":[0,9,15],"to":[16,15,16],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}}
+  ]
 }

src/main/resources/assets/rivencraft/models/block/writing_desk_extension.json

@@ -0,0 +1,11 @@
+{
+  "parent": "minecraft:block/block",
+  "textures": {"wood":"rivencraft:block/writing_desk_wood","inlay":"rivencraft:block/writing_desk_inlay","particle":"rivencraft:block/writing_desk_wood"},
+  "elements": [
+    {"from":[0,0,1],"to":[16,1,15],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}},
+    {"from":[0,8,0],"to":[16,9,16],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}},
+    {"from":[15,0,1],"to":[16,8,15],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}},
+    {"from":[0,3,1],"to":[15,4,15],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}},
+    {"from":[0,9,15],"to":[16,15,16],"faces":{"up":{"texture":"#wood"},"down":{"texture":"#wood"},"north":{"texture":"#wood"},"south":{"texture":"#wood"},"east":{"texture":"#wood"},"west":{"texture":"#wood"}}}
+  ]
+}

src/main/resources/assets/rivencraft/models/item/writing_desk.json

@@ -1,4 +1,4 @@
 {
   "parent": "minecraft:item/generated",
-  "textures": { "layer0": "rivencraft:item/writing_desk" }
+  "textures": {"layer0": "rivencraft:item/writing_desk"}
 }

src/main/resources/data/rivencraft/recipe/page.json

@@ -1,13 +0,0 @@
-{
-  "type": "minecraft:crafting_shapeless",
-  "category": "misc",
-  "ingredients": [
-    {
-      "item": "minecraft:paper"
-    }
-  ],
-  "result": {
-    "count": 1,
-    "id": "rivencraft:page"
-  }
-}