Add Writing Desk paper copying and ink meter

README.md

@@ -19,12 +19,20 @@ 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`.
-Symbol-page transcription will become available through the Writing Desk.
+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, ink/source/page work slots, and inventory persist
+Its four 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,
-and right inventory. Transcription controls are not implemented yet.
+and right inventory. Put vanilla paper (or a blank Rivencraft Page) 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
+returns a vanilla glass bottle to the lower-right slot. Writing new symbols
+from a catalog remains future work.
+Selecting a stored page on the desk surface shows its Legacy-proportioned
+portrait preview and name above the player inventory.
 
 ## Linking Book
 

docs/WRITING_DATA.md

@@ -86,5 +86,8 @@ panel, hold a blank Page in one hand and use an Ink Vial in the other. The
 server checks the held items, blank state, and sufficient ink before consuming
 anything. A stack of blank Pages yields exactly one Link Panel Page per use;
 if the inventory is full, the result is dropped instead of deleted. Symbol
-copying will be implemented by the Writing Desk. Link-property modifiers are
+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
+desk's 16-unit ink meter refills from an Ink Vial when needed and returns a
+vanilla glass bottle. Link-property modifiers are
 deferred beyond this baseline flow.

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=0.3.5.0
+mod_version=0.3.5.2
 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/entity/WritingDeskBlockEntity.java

@@ -1,5 +1,8 @@
 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;
 import net.minecraft.core.BlockPos;
@@ -10,25 +13,29 @@ 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.block.entity.BlockEntity;
 import net.minecraft.world.level.block.state.BlockState;
 
-/** The four Legacy-like collection tabs and four work slots are owned by the block, not its viewers. */
+/** Four 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 INK = 4;
-    public static final int SOURCE = 5;
+    public static final int RETURN = 5;
     public static final int PAPER = 6;
-    public static final int OUTPUT = 7;
+    /** Unused by new desks; retained so old saves cannot silently lose slot contents. */
+    public static final int LEGACY_OUTPUT = 7;
     public static final int SIZE = 8;
     private NonNullList<ItemStack> items = NonNullList.withSize(SIZE, ItemStack.EMPTY);
     private int activeCollection;
+    private int inkRemaining;
 
     public WritingDeskBlockEntity(BlockPos pos, BlockState state) {
         super(ModBlockEntities.WRITING_DESK.get(), pos, state);
     }
 
     public int activeCollection() { return activeCollection; }
+    public int inkRemaining() { return inkRemaining; }
     public void setActiveCollection(int index) {
         if (index >= 0 && index < COLLECTIONS && activeCollection != index) {
             activeCollection = index;
@@ -60,15 +67,49 @@ public final class WritingDeskBlockEntity extends BlockEntity implements Contain
         if (slot < COLLECTIONS) return stack.is(ModItems.NOTEBOOK.get()) || stack.is(ModItems.PAGE.get());
         return switch (slot) {
             case INK -> stack.is(ModItems.INK_VIAL.get());
-            case SOURCE -> stack.is(ModItems.PAGE.get()) || stack.is(ModItems.NOTEBOOK.get());
-            case PAPER -> stack.is(ModItems.PAGE.get());
-            case OUTPUT -> false;
+            case RETURN -> false;
+            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;
         };
     }
+
+    /** 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);
+        if (!canPlaceItem(PAPER, paper) || paper.isEmpty()) return false;
+        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)
+                && returned.getCount() < returned.getMaxStackSize());
+    }
+
+    public boolean consumeCopyMaterials() {
+        if (!canConsumeCopyMaterials()) return false;
+        int cost = WritingInkService.symbolCopyCost();
+        if (inkRemaining < cost) {
+            ItemStack vial = items.get(INK);
+            inkRemaining += Math.clamp(InkVialItem.remaining(vial), 0, InkVialItem.CAPACITY);
+            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);
+        }
+        inkRemaining -= cost;
+        removeItem(PAPER, 1);
+        setChanged();
+        return true;
+    }
     @Override public void clearContent() {
         items.clear();
         items = NonNullList.withSize(SIZE, ItemStack.EMPTY);
+        inkRemaining = 0;
         setChanged();
     }
     @Override protected void loadAdditional(CompoundTag tag, HolderLookup.Provider registries) {
@@ -76,10 +117,12 @@ public final class WritingDeskBlockEntity extends BlockEntity implements Contain
         items = NonNullList.withSize(SIZE, ItemStack.EMPTY);
         ContainerHelper.loadAllItems(tag, items, registries);
         activeCollection = Math.clamp(tag.getInt("ActiveCollection"), 0, COLLECTIONS - 1);
+        inkRemaining = Math.clamp(tag.getInt("InkRemaining"), 0, InkVialItem.CAPACITY);
     }
     @Override protected void saveAdditional(CompoundTag tag, HolderLookup.Provider registries) {
         super.saveAdditional(tag, registries);
         ContainerHelper.saveAllItems(tag, items, registries);
         tag.putInt("ActiveCollection", activeCollection);
+        tag.putInt("InkRemaining", inkRemaining);
     }
 }

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

@@ -271,7 +271,7 @@ public final class NotebookScreen extends AbstractContainerScreen<NotebookMenu>
         }
     }
 
-    private static ResourceLocation symbolTexture(ItemStack page) {
+    static ResourceLocation symbolTexture(ItemStack page) {
         var content = PageItem.content(page);
         if (content.kind() == net.dnorberg.rivencraft.writing.PageContent.Kind.UNRESOLVED_SYMBOL) {
             return UNRESOLVED_SYMBOL;

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

@@ -1,13 +1,27 @@
 package net.dnorberg.rivencraft.client.screen;
 
+import java.util.List;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.item.PageItem;
 import net.dnorberg.rivencraft.menu.WritingDeskMenu;
+import net.dnorberg.rivencraft.registry.ModDataComponents;
+import net.dnorberg.rivencraft.registry.ModItems;
+import net.dnorberg.rivencraft.writing.NotebookContents;
 import net.minecraft.client.gui.GuiGraphics;
 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.item.ItemStack;
 
 /** Functional storage surface; full Legacy transcription controls are a later Milestone 4 slice. */
 public final class WritingDeskScreen extends AbstractContainerScreen<WritingDeskMenu> {
+    private static final ResourceLocation PAGE_ATLAS = ResourceLocation.fromNamespaceAndPath(
+            Rivencraft.MOD_ID, "textures/gui/notebook_pages.png");
+    private int lastCollection = -1;
+    private int selectedPage;
+    private int scrollRows;
+
     public WritingDeskScreen(WritingDeskMenu menu, Inventory inventory, Component title) {
         super(menu, inventory, title);
         imageWidth = 398;
@@ -17,6 +31,10 @@ public final class WritingDeskScreen extends AbstractContainerScreen<WritingDesk
         inventoryLabelY = 79;
     }
 
+    @Override public void renderBackground(GuiGraphics graphics, int mouseX, int mouseY, float partialTick) {
+        // Legacy leaves the world visible around the desk instead of dimming it.
+    }
+
     @Override protected void renderBg(GuiGraphics graphics, float partialTick, int mouseX, int mouseY) {
         int x = leftPos;
         int y = topPos;
@@ -29,10 +47,15 @@ public final class WritingDeskScreen extends AbstractContainerScreen<WritingDesk
                     i == menu.activeCollection() ? 0xFF7777B6 : 0xFF999999);
             slotFrame(graphics, 12, 20 + i * 37);
         }
+        slotFrame(graphics, 370, 20);
         slotFrame(graphics, 228, 20);
-        slotFrame(graphics, 266, 20);
-        slotFrame(graphics, 304, 20);
-        slotFrame(graphics, 342, 20);
+        slotFrame(graphics, 228, 57);
+        slotFrame(graphics, 370, 57);
+        graphics.fill(x + 350, y + 20, x + 364, y + 75, 0xFF303035);
+        graphics.fill(x + 352, y + 22, x + 362, y + 73, 0xFF15151B);
+        int filled = 51 * menu.inkRemaining() / 16;
+        if (filled > 0) graphics.fill(x + 352, y + 73 - filled, x + 362, y + 73, 0xFF6666AA);
+        graphics.renderOutline(x + 350, y + 20, 14, 55, 0xFF484848);
         for (int row = 0; row < 3; row++) {
             for (int column = 0; column < 9; column++) slotFrame(graphics, 224 + column * 18, 91 + row * 18);
         }
@@ -46,12 +69,91 @@ public final class WritingDeskScreen extends AbstractContainerScreen<WritingDesk
                 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);
+    }
+
     @Override public void render(GuiGraphics graphics, int mouseX, int mouseY, float partialTick) {
         super.render(graphics, mouseX, mouseY, partialTick);
+        renderCollection(graphics);
         renderTooltip(graphics, mouseX, mouseY);
+        if (mouseX >= leftPos + 350 && mouseX < leftPos + 364
+                && mouseY >= topPos + 20 && mouseY < topPos + 75) {
+            graphics.renderTooltip(font, Component.translatable("screen.rivencraft.writing_desk.ink",
+                    menu.inkRemaining(), 16), mouseX, mouseY);
+        }
+    }
+
+    private List<ItemStack> pages() {
+        ItemStack collection = menu.getSlot(menu.activeCollection()).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();
+        }
+        return List.of();
+    }
+
+    private void renderCollection(GuiGraphics graphics) {
+        List<ItemStack> pages = pages();
+        if (lastCollection != menu.activeCollection()) {
+            lastCollection = menu.activeCollection();
+            scrollRows = 0;
+            selectedPage = 0;
+        }
+        int last = -1;
+        for (int i = 0; i < pages.size(); i++) if (!pages.get(i).isEmpty()) last = 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);
+            int x = leftPos + 48 + column * 31;
+            int y = topPos + 18 + 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);
+        }
+        if (selectedPage >= pages.size() || pages.get(selectedPage).isEmpty()) return;
+        ItemStack selected = pages.get(selectedPage);
+        graphics.pose().pushPose();
+        graphics.pose().translate(leftPos + 294, topPos + 12, 0);
+        graphics.pose().scale(1.35F, 1.35F, 1.0F);
+        drawPage(graphics, selected, 0, 0);
+        graphics.pose().popPose();
+        String title = font.plainSubstrByWidth(selected.getHoverName().getString(), 112);
+        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) {
+        graphics.blit(PAGE_ATLAS, x, y, 30, 40, 156, 0, 30, 40, 256, 256);
+        if (page.isEmpty()) return;
+        switch (PageItem.content(page).kind()) {
+            case BLANK -> { }
+            case LINK_PANEL -> graphics.fill(x + 5, y + 6, x + 25, y + 20, 0xFF000000);
+            case SYMBOL, UNRESOLVED_SYMBOL -> graphics.blit(NotebookScreen.symbolTexture(page), x + 1, y + 6,
+                    28, 28, 16, 16, 96, 96, 128, 128);
+        }
     }
 
     @Override public boolean mouseClicked(double mouseX, double mouseY, int button) {
+        if (button == 0) {
+            int x = (int) mouseX - leftPos - 48;
+            int y = (int) mouseY - topPos - 18;
+            if (x >= 0 && x < 155 && y >= 0 && y < 123) {
+                int column = x / 31;
+                int row = y / 41;
+                int index = (row + scrollRows) * 5 + column;
+                List<ItemStack> pages = pages();
+                if (x % 31 < 30 && y % 41 < 40 && index < pages.size()
+                        && !pages.get(index).isEmpty()) {
+                    selectedPage = index;
+                    if (minecraft != null && minecraft.gameMode != null) {
+                        minecraft.gameMode.handleInventoryButtonClick(menu.containerId, 16 + index);
+                    }
+                }
+                return true;
+            }
+        }
         if (button == 0 && mouseX >= leftPos + 29 && mouseX < leftPos + 40) {
             for (int i = 0; i < 4; i++) {
                 int top = topPos + 16 + i * 37;
@@ -65,4 +167,14 @@ public final class WritingDeskScreen extends AbstractContainerScreen<WritingDesk
         }
         return super.mouseClicked(mouseX, mouseY, button);
     }
+
+    @Override public boolean mouseScrolled(double mouseX, double mouseY, double scrollX, double scrollY) {
+        if (mouseX >= leftPos + 48 && mouseX < leftPos + 203
+                && mouseY >= topPos + 18 && mouseY < topPos + 141) {
+            int rows = (pages().size() + 4) / 5;
+            scrollRows = Math.clamp(scrollRows - (int) Math.signum(scrollY), 0, Math.max(0, rows - 3));
+            return true;
+        }
+        return super.mouseScrolled(mouseX, mouseY, scrollX, scrollY);
+    }
 }

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

@@ -1,15 +1,21 @@
 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.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.minecraft.core.BlockPos;
 import net.minecraft.gametest.framework.GameTest;
 import net.minecraft.gametest.framework.GameTestHelper;
 import net.minecraft.world.entity.item.ItemEntity;
 import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+import net.minecraft.world.inventory.ClickType;
 import net.minecraft.world.level.block.Blocks;
 import net.minecraft.world.phys.AABB;
 import net.neoforged.neoforge.gametest.GameTestHolder;
@@ -65,21 +71,139 @@ public final class WritingDeskGameTests {
         WritingDeskBlockEntity desk = (WritingDeskBlockEntity) helper.getLevel().getBlockEntity(pos);
         var player = helper.makeMockServerPlayerInLevel();
         player.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
-        player.getInventory().setItem(9, new ItemStack(ModItems.PAGE.get(), 12));
+        player.getInventory().setItem(9, new ItemStack(Items.PAPER, 12));
         WritingDeskMenu menu = new WritingDeskMenu(1, player.getInventory(), desk);
         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, 8);
+        menu.quickMoveStack(player, 9);
         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);
         helper.assertTrue(desk.getItem(WritingDeskBlockEntity.PAPER).isEmpty(), "Shift-click must empty desk source slot");
-        int total = player.getInventory().items.stream().filter(stack -> stack.is(ModItems.PAGE.get()))
+        int total = player.getInventory().items.stream().filter(stack -> stack.is(Items.PAPER))
                 .mapToInt(ItemStack::getCount).sum();
         helper.assertValueEqual(total, 12, "Round-trip must not lose or duplicate pages");
         helper.getLevel().setBlock(pos, Blocks.AIR.defaultBlockState(), 3);
         helper.assertFalse(menu.stillValid(player), "Removed desk must invalidate menu");
         helper.succeed();
     }
+
+    @GameTest(template = "empty")
+    public static void takingCopySpendsPaperAndOneInkThenReturnsGlassBottle(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 source = PageItem.createLinkPanelPage();
+        desk.setItem(0, source.copy());
+        desk.setItem(WritingDeskBlockEntity.PAPER, new ItemStack(Items.PAPER, 2));
+        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);
+        menu.broadcastChanges();
+        helper.assertTrue(menu.getSlot(WritingDeskMenu.COPY_RESULT).getItem().is(ModItems.PAGE.get()),
+                "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");
+        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.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");
+        helper.assertTrue(desk.getItem(0).is(ModItems.PAGE.get()), "Source page must remain untouched");
+        helper.assertTrue(menu.quickMoveStack(player, WritingDeskMenu.COPY_RESULT).is(ModItems.PAGE.get()),
+                "A second copy must remain available from the same ink fill");
+        helper.assertTrue(desk.getItem(WritingDeskBlockEntity.PAPER).isEmpty(),
+                "Two copies must consume exactly two paper");
+        helper.assertValueEqual(desk.inkRemaining(), 14, "Two copies must spend exactly two of sixteen ink");
+        helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.RETURN).getCount(), 1,
+                "A second copy must not consume another vial");
+        var saved = desk.saveWithoutMetadata(helper.getLevel().registryAccess());
+        var restored = new WritingDeskBlockEntity(pos, ModBlocks.WRITING_DESK.get().defaultBlockState());
+        restored.loadWithComponents(saved, helper.getLevel().registryAccess());
+        helper.assertValueEqual(restored.inkRemaining(), 14, "Ink meter must persist across saves");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void shiftClickCopiesOnlyWhenResourcesAndBottleSpaceExist(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, 2));
+        desk.setItem(WritingDeskBlockEntity.INK, new ItemStack(ModItems.INK_VIAL.get()));
+        desk.setItem(WritingDeskBlockEntity.RETURN, new ItemStack(Items.GLASS_BOTTLE, 64));
+        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.assertTrue(menu.quickMoveStack(player, WritingDeskMenu.COPY_RESULT).isEmpty(),
+                "Full bottle return must block refill without consuming supplies");
+        helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.PAPER).getCount(), 2,
+                "Blocked copy must leave paper untouched");
+        desk.removeItem(WritingDeskBlockEntity.RETURN, 1);
+        ItemStack copied = menu.quickMoveStack(player, WritingDeskMenu.COPY_RESULT);
+        helper.assertTrue(copied.is(ModItems.PAGE.get()), "Shift-click must transfer one copy");
+        helper.assertValueEqual(desk.getItem(WritingDeskBlockEntity.PAPER).getCount(), 1,
+                "Shift-click must consume one paper");
+        helper.assertValueEqual(desk.inkRemaining(), 15, "Shift-click must consume one ink");
+        int copies = player.getInventory().items.stream().filter(stack -> stack.is(ModItems.PAGE.get()))
+                .mapToInt(ItemStack::getCount).sum();
+        helper.assertValueEqual(copies, 1, "Shift-click must give exactly one page");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void selectedNotebookPageControlsCopyPreview(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 notebook = new ItemStack(ModItems.NOTEBOOK.get());
+        notebook.set(ModDataComponents.NOTEBOOK_CONTENTS.get(),
+                new NotebookContents(List.of(ItemStack.EMPTY, PageItem.createLinkPanelPage())));
+        desk.setItem(0, 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);
+        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");
+        menu.broadcastChanges();
+        helper.assertTrue(menu.getSlot(WritingDeskMenu.COPY_RESULT).getItem().is(ModItems.PAGE.get()),
+                "Selecting the populated page must show a copy");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void twoViewersCannotTakeTheSameLastSheet(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 first = helper.makeMockServerPlayerInLevel();
+        var second = helper.makeMockServerPlayerInLevel();
+        first.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        second.moveTo(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        WritingDeskMenu firstMenu = new WritingDeskMenu(1, first.getInventory(), desk);
+        WritingDeskMenu secondMenu = new WritingDeskMenu(2, second.getInventory(), desk);
+        firstMenu.broadcastChanges();
+        secondMenu.broadcastChanges();
+        helper.assertTrue(firstMenu.quickMoveStack(first, WritingDeskMenu.COPY_RESULT).is(ModItems.PAGE.get()),
+                "First viewer should take the last available copy");
+        helper.assertTrue(secondMenu.quickMoveStack(second, WritingDeskMenu.COPY_RESULT).isEmpty(),
+                "Second viewer must not copy the already-consumed paper");
+        helper.assertTrue(desk.getItem(WritingDeskBlockEntity.PAPER).isEmpty(),
+                "Shared desk must spend paper only once");
+        helper.succeed();
+    }
 }

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

@@ -1,8 +1,13 @@
 package net.dnorberg.rivencraft.menu;
 
 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.dnorberg.rivencraft.registry.ModMenus;
+import net.dnorberg.rivencraft.writing.NotebookContents;
+import net.dnorberg.rivencraft.writing.PageContent;
+import java.util.List;
 import net.minecraft.network.RegistryFriendlyByteBuf;
 import net.minecraft.world.Container;
 import net.minecraft.world.SimpleContainer;
@@ -12,12 +17,18 @@ import net.minecraft.world.inventory.AbstractContainerMenu;
 import net.minecraft.world.inventory.DataSlot;
 import net.minecraft.world.inventory.Slot;
 import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
 
 public final class WritingDeskMenu extends AbstractContainerMenu {
-    private static final int PLAYER_START = WritingDeskBlockEntity.SIZE;
+    public static final int COPY_RESULT = WritingDeskBlockEntity.SIZE;
+    private static final int PLAYER_START = COPY_RESULT + 1;
     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 selectedPage;
 
     public WritingDeskMenu(int id, Inventory inventory, RegistryFriendlyByteBuf data) {
         this(id, inventory, inventory.player.level().getBlockEntity(data.readBlockPos())
@@ -28,18 +39,25 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
         super(ModMenus.WRITING_DESK.get(), id);
         this.blockEntity = blockEntity;
         this.desk = blockEntity == null ? new SimpleContainer(WritingDeskBlockEntity.SIZE) : blockEntity;
+        this.clientSide = inventory.player.level().isClientSide;
         addDataSlot(new DataSlot() {
             @Override public int get() { return WritingDeskMenu.this.blockEntity == null
                     ? syncedActiveCollection : WritingDeskMenu.this.blockEntity.activeCollection(); }
             @Override public void set(int value) { syncedActiveCollection = value; }
         });
+        addDataSlot(new DataSlot() {
+            @Override public int get() { return WritingDeskMenu.this.blockEntity == null
+                    ? syncedInkRemaining : WritingDeskMenu.this.blockEntity.inkRemaining(); }
+            @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, WritingDeskBlockEntity.INK, 228, 20, 1));
-        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.SOURCE, 266, 20, 1));
-        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.PAPER, 304, 20, 64));
-        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.OUTPUT, 342, 20, 64));
+        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.INK, 370, 20, 16));
+        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.RETURN, 370, 57, 64));
+        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.PAPER, 228, 20, 64));
+        addSlot(new DeskSlot(desk, WritingDeskBlockEntity.LEGACY_OUTPUT, -1000, -1000, 64));
+        addSlot(new CopySlot(result, 0, 228, 57));
         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));
@@ -51,10 +69,17 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
     }
 
     public int activeCollection() { return syncedActiveCollection; }
+    public int inkRemaining() { return syncedInkRemaining; }
 
     @Override public boolean clickMenuButton(Player player, int id) {
-        if (blockEntity == null || !stillValid(player) || id < 0 || id >= WritingDeskBlockEntity.COLLECTIONS) return false;
-        blockEntity.setActiveCollection(id);
+        if (blockEntity == null || !stillValid(player)) return false;
+        if (id >= 0 && id < WritingDeskBlockEntity.COLLECTIONS) {
+            blockEntity.setActiveCollection(id);
+            selectedPage = 0;
+        } else if (id >= 16 && id < 16 + NotebookContents.MAX_PAGES) {
+            selectedPage = id - 16;
+        } else return false;
+        refreshOutput();
         return true;
     }
 
@@ -64,11 +89,23 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
 
     @Override public ItemStack quickMoveStack(Player player, int index) {
         if (!stillValid(player) || index < 0 || index >= slots.size()) return ItemStack.EMPTY;
+        if (index == COPY_RESULT) {
+            refreshOutput();
+            if (!canCopy()) return ItemStack.EMPTY;
+            ItemStack copy = selectedSource().copyWithCount(1);
+            ItemStack movingCopy = copy.copy();
+            if (!moveItemStackTo(movingCopy, PLAYER_START, slots.size(), true) || !movingCopy.isEmpty()) {
+                return ItemStack.EMPTY;
+            }
+            blockEntity.consumeCopyMaterials();
+            refreshOutput();
+            return copy;
+        }
         Slot slot = slots.get(index);
         if (!slot.hasItem()) return ItemStack.EMPTY;
         ItemStack moving = slot.getItem();
         ItemStack original = moving.copy();
-        if (index < PLAYER_START) {
+        if (index < COPY_RESULT) {
             if (!moveItemStackTo(moving, PLAYER_START, slots.size(), true)) return ItemStack.EMPTY;
         } else if (!moveIntoDesk(moving)) {
             return ItemStack.EMPTY;
@@ -81,14 +118,65 @@ 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.NOTEBOOK.get())) return moveItemStackTo(moving, 0, 4, false);
-        if (moving.is(ModItems.PAGE.get())) {
-            return moveItemStackTo(moving, 6, 7, false)
-                    || moveItemStackTo(moving, 0, 4, false)
-                    || moveItemStackTo(moving, 5, 6, false);
-        }
+        if (moving.is(Items.PAPER) || moving.is(ModItems.PAGE.get())
+                && PageItem.content(moving).kind() == PageContent.Kind.BLANK)
+            return moveItemStackTo(moving, WritingDeskBlockEntity.PAPER,
+                    WritingDeskBlockEntity.PAPER + 1, false);
+        if (moving.is(ModItems.PAGE.get())) return moveItemStackTo(moving, 0, 4, false);
         return false;
     }
 
+    private ItemStack selectedSource() {
+        ItemStack collection = desk.getItem(blockEntity == null ? syncedActiveCollection : blockEntity.activeCollection());
+        if (collection.is(ModItems.PAGE.get())) return selectedPage == 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 ItemStack.EMPTY;
+    }
+
+    private boolean canCopy() {
+        ItemStack source = selectedSource();
+        return blockEntity != null && source.is(ModItems.PAGE.get())
+                && PageItem.content(source).kind() != PageContent.Kind.BLANK
+                && PageItem.isUsableWriting(source) && blockEntity.canConsumeCopyMaterials();
+    }
+
+    private void refreshOutput() {
+        if (clientSide) return;
+        ItemStack preview = canCopy() ? selectedSource().copyWithCount(1) : ItemStack.EMPTY;
+        if (!ItemStack.matches(result.getItem(0), preview)) result.setItem(0, preview);
+    }
+
+    @Override public void broadcastChanges() {
+        refreshOutput();
+        super.broadcastChanges();
+    }
+
+    @Override public void clicked(int slotId, int button, net.minecraft.world.inventory.ClickType clickType,
+                                  Player player) {
+        if (!stillValid(player)) {
+            player.closeContainer();
+            return;
+        }
+        refreshOutput();
+        super.clicked(slotId, button, clickType, player);
+    }
+
+    private final class CopySlot extends Slot {
+        private CopySlot(Container container, int index, int x, int y) { super(container, index, x, y); }
+        @Override public boolean mayPlace(ItemStack stack) { return false; }
+        @Override public boolean mayPickup(Player player) {
+            return clientSide ? hasItem() : WritingDeskMenu.this.stillValid(player) && canCopy();
+        }
+        @Override public void onTake(Player player, ItemStack stack) {
+            if (!clientSide && blockEntity.consumeCopyMaterials()) refreshOutput();
+            super.onTake(player, stack);
+        }
+    }
+
     private static final class DeskSlot extends Slot {
         private final int limit;
         private DeskSlot(Container container, int index, int x, int y, int limit) {

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

@@ -18,6 +18,7 @@
   "item.rivencraft.ink_vial": "Ink Vial",
   "block.rivencraft.writing_desk": "Writing Desk",
   "container.rivencraft.writing_desk": "Writing Desk",
+  "screen.rivencraft.writing_desk.ink": "Ink: %s/%s",
   "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.",
   "screen.rivencraft.notebook.search": "Search pages",