Union union/pt2-e: #3544 7e459e5fb

Launcher: a Nightly row in Versions reads as its commit

.github/pull_request_template.md

@@ -1,3 +1,5 @@
+<!-- Opened by an AI agent? First line: "> 🤖 Opened by <your GitHub login>'s AI agent (<tool, model>), not by <your GitHub login> personally." Use your own login, not someone else's. -->
+
 ## What and why
 
 <!-- What this changes, and why. Link the issue it fixes ("Fixes #123"). -->

AGENTS.md

@@ -13,13 +13,15 @@ Feature → files → harness for the most-changed areas: [docs/architecture.md]
   `XDG_CONFIG_HOME`, plus `HORIZON_LAUNCHER_NO_SELF_UPDATE=1` and `HORIZON_NO_AUDIO=1`, and, for the
   launcher, `HORIZON_LAUNCHER_TRASH`, `HORIZON_LAUNCHER_CLIPBOARD` and `HORIZON_LAUNCHER_DESKTOP` pointing into the scratch home. Never write to
   `~/.local/share/{applications,horizon,horizon-launcher}` or `~/.local/bin`.
-- **Mark what an agent posts.** A PR body starts with a line naming whose agent opened it and with what.
-  Ludovic's agents write `> 🤖 Opened by Ludovic's AI agent (Claude), not by Ludovic himself.`, and a
-  contributor's agent names its own person and tool (issues: "Filed by", reviews: "Review by"). Every
-  comment starts with `🤖 Agent:`. Never write as Ludovic or as anyone else.
+- **Mark what an agent posts.** A PR body starts with a line naming the person whose agent opened it and
+  the tool: `> 🤖 Opened by <login>'s AI agent (<tool, model>), not by <login> personally.`, where `<login>`
+  is the GitHub account the PR is opened from (`gh api user --jq .login`). Issues say "Filed by", reviews
+  "Review by". Every comment starts with `🤖 Agent:`. Write only as the person you work for: the lines on
+  this page that name Ludovic are for his own agents (account `ludovic111`), never for anyone else's.
 - **Attribution.** Commits end with a `Co-Authored-By:` line for the agent that wrote them, and PR bodies
-  with that agent's own "Generated with" line. Ludovic's agents use
-  `Co-Authored-By: Claude <model> <[email protected]>` and
+  with that agent's own "Generated with" line. Example, Ludovic's agents (Claude Code on `ludovic111`):
+  first line `> 🤖 Opened by Ludovic's AI agent (Claude), not by Ludovic himself.`, commits
+  `Co-Authored-By: Claude <model> <[email protected]>`, last line
   `🤖 Generated with [Claude Code](https://claude.com/claude-code)`.
 - Everything players run is Rust. Python/Java only for dev tools and harness drivers in `tools/`.
 - Horizon-only features follow [docs/design-system.md](docs/design-system.md) and are off by default where

README.md

@@ -46,7 +46,7 @@ The [documentation](https://playhorizon.dev/docs/) covers each of these.
 
 - **The game:** singleplayer with vanilla's world generation, mobs, villagers, raids, redstone, every command, the HUD and the recipe book, on saves in vanilla's format. Worlds from 1.8 to 26.2 are upgraded as vanilla does. [Status table](#project-status).
 - **Horizon's own extras:** new menus (vanilla's are one setting away), graphics presets, distant terrain up to 1024 chunks, controller support, optional zoom, minimap and more, all off by default where they would change the vanilla look. See [Settings](https://playhorizon.dev/docs/settings).
-- **Resource packs and data packs:** resource packs work, and data packs load functions, predicates and item modifiers.
+- **Resource packs and data packs:** resource packs work, and data packs load functions, predicates, item modifiers and world generation (vanilla's heights and biomes for now).
 - **Playing with others:** invite friends from the pause menu's Friends button with a code, Open to LAN, and joining servers, online-mode ones with the Microsoft account the launcher signs in with. See [Multiplayer](https://playhorizon.dev/docs/multiplayer).
 - **Mods:** Horizon has its own mods, installed from the launcher. The official ones (Zoom, FPS Counter, Keystrokes and Minimap) are native Rust that the launcher builds into your game, with no Rust to install; older WebAssembly mods still run while they move. Java mod jars do not run in Horizon. See [Mods and data packs](https://playhorizon.dev/docs/mods).
 

crates/horizon-client-core/src/block_entity_nbt.rs

@@ -494,7 +494,11 @@ pub fn canonical(tag: &Tag) -> Option<Tag> {
                     _ => string("minecraft:air"),
                 },
             );
-            f.put("facing", Tag::Int(int(tag.get("facing")).unwrap_or(0)));
+            // Direction.LEGACY_ID_CODEC: the 3D data value as a byte.
+            f.put(
+                "facing",
+                Tag::Byte(int(tag.get("facing")).unwrap_or(0) as i8),
+            );
             f.float("progress", 0.0);
             f.flag("extending", false);
             f.flag("source", false);
@@ -873,6 +877,23 @@ mod tests {
         );
     }
 
+    /// `PistonMovingBlockEntity.saveAdditional`: `facing` through
+    /// `Direction.LEGACY_ID_CODEC` (a byte), `progress` a float.
+    #[test]
+    fn moving_piston_fields_match_vanilla() {
+        let out = canon(
+            "{id:\"minecraft:piston\",x:1,y:2,z:3,blockState:{Name:\"minecraft:stone\"},\
+             facing:5,progress:0.5f,extending:1b,source:0b}",
+        );
+        assert_eq!(out.get("facing"), Some(&Tag::Byte(5)));
+        assert_eq!(out.get("progress"), Some(&f32_tag(0.5)));
+        assert_eq!(out.get("extending"), Some(&Tag::Byte(1)));
+        assert_eq!(out.get("source"), Some(&Tag::Byte(0)));
+        let fresh = canon("{id:\"minecraft:piston\",x:1,y:2,z:3}");
+        assert_eq!(fresh.get("facing"), Some(&Tag::Byte(0)));
+        assert_eq!(fresh.get("blockState"), Some(&string("minecraft:air")));
+    }
+
     #[test]
     fn loot_table_replaces_items_and_zero_seed_is_omitted() {
         let out = canon(

crates/horizon-client-core/src/lang.rs

@@ -60,6 +60,9 @@ impl ResourceSource for Bundled {
             "assets/horizon/lang/ru_ru.json" => {
                 include_str!("../../horizon-client/assets/horizon/lang/ru_ru.json")
             }
+            "assets/horizon/lang/uk_ua.json" => {
+                include_str!("../../horizon-client/assets/horizon/lang/uk_ua.json")
+            }
             _ => return None,
         };
         Some(body.as_bytes().to_vec())
@@ -266,6 +269,18 @@ mod tests {
         assert_eq!(en.get("horizon.options.controller"), Some("Controller"));
         let ru = Language::load(&[&empty], "ru_ru");
         assert_eq!(ru.get("horizon.options.controller"), Some("Геймпад"));
+        // Every bundled string carries both languages: a key added to one file
+        // and forgotten in the other shows as a key name on screen.
+        for key in en.map().keys() {
+            assert!(ru.get(key).is_some(), "{key} has no ru_ru value");
+        }
+        assert_eq!(en.get("horizon.pages.mods"), Some("Mods"));
+        assert_eq!(ru.get("horizon.pages.mods"), Some("Моды"));
+        let uk = Language::load(&[&empty], "uk_ua");
+        assert_eq!(
+            uk.get("horizon.options.on_screen_keyboard"),
+            Some("Екранна клавіатура")
+        );
     }
 
     #[test]

crates/horizon-client-core/src/registries.rs

@@ -54,6 +54,12 @@ pub struct Registries {
     pub function_tags: Vec<String>,
     /// The block the source is looking at (relevant coordinates).
     pub target_block: Option<[i32; 3]>,
+    /// `ClientSuggestionProvider.getSelectedEntities`: the UUID of the
+    /// entity under the crosshair (`Entity.getStringUUID`), if any.
+    pub selected_entities: Vec<String>,
+    /// `ClientSuggestionProvider.getAbsoluteCoordinates`: the exact point of
+    /// that block hit, each coordinate as `%.2f` (`Locale.ROOT`).
+    pub target_point: Option<[String; 3]>,
     /// Every registry's element and tag ids (`minecraft:item` -> ...), as
     /// the server's registry access and reloadable registries hold them.
     pub by_registry: BTreeMap<String, RegistryIds>,

crates/horizon-client-core/src/scoreboard.rs

@@ -662,10 +662,22 @@ pub fn name_shown(own: Option<&Team>, viewer: Option<&Team>, v: NameView) -> boo
     }
     !v.hud_hidden && !v.is_camera && visible && !v.is_vehicle
 }
-/// `ServerPlayer.die`: whether a player's death message reaches the player
-/// themselves (the team broadcasts leave out the dying player).
-pub fn own_death_message_shown(team: Option<&Team>) -> bool {
-    team.is_none_or(|t| t.death_message_visibility == Visibility::Always)
+/// `ServerPlayer.die`: whether `other` hears the death message of `dying`
+/// (`broadcastSystemMessage`, `broadcastSystemToTeam` or
+/// `broadcastSystemToAllExceptTeam`, by the team's death message visibility).
+pub fn death_message_reaches(board: &Scoreboard, dying: &str, other: &str) -> bool {
+    let Some(team) = board.players_team(dying) else {
+        return true;
+    };
+    let same_team = board
+        .players_team(other)
+        .is_some_and(|t| t.name == team.name);
+    match team.death_message_visibility {
+        Visibility::Always => true,
+        Visibility::Never => false,
+        Visibility::HideForOtherTeams => same_team && other != dying,
+        Visibility::HideForOwnTeam => !same_team,
+    }
 }
 
 // ---- objectives and scores ---------------------------------------------
@@ -1551,3 +1563,49 @@ mod tests {
         );
     }
 }
+
+/// `DamageSource.getLocalizedDeathMessage`: the cause's item with a custom
+/// name gets the `<id>.item` message, with the item's name as a third
+/// argument.
+pub fn death_message_args(
+    key: &str,
+    victim: &Text,
+    cause: &Text,
+    item: Option<&Text>,
+) -> (String, Vec<Text>) {
+    match item {
+        Some(item) => (
+            format!("{key}.item"),
+            vec![victim.clone(), cause.clone(), item.clone()],
+        ),
+        None => (key.to_owned(), vec![victim.clone(), cause.clone()]),
+    }
+}
+
+#[cfg(test)]
+mod death_message_tests {
+    use super::*;
+
+    #[test]
+    fn the_death_message_names_the_causes_item_when_it_has_a_custom_name() {
+        let victim = Text::literal("Steve");
+        let cause = Text::literal("Zombie");
+        // DamageSource.getLocalizedDeathMessage: the item variant, with the
+        // item's name as the third argument.
+        let (key, args) = death_message_args(
+            "death.attack.arrow",
+            &victim,
+            &cause,
+            Some(&Text::literal("My Sword")),
+        );
+        assert_eq!(key, "death.attack.arrow.item");
+        assert_eq!(args.len(), 3);
+        assert_eq!(args[0].plain(), "Steve");
+        assert_eq!(args[1].plain(), "Zombie");
+        assert_eq!(args[2].plain(), "My Sword");
+        // Without a custom name the message keeps its two arguments.
+        let (key, args) = death_message_args("death.attack.arrow", &victim, &cause, None);
+        assert_eq!(key, "death.attack.arrow");
+        assert_eq!(args.len(), 2);
+    }
+}

crates/horizon-client-input/src/clipboard.rs

@@ -60,6 +60,19 @@ pub fn edit_shortcut(
     })
 }
 
+/// Windows reports AltGr as Ctrl plus Alt: the system presses a left Control
+/// in front of the right Alt.
+pub const ALTGR_IS_CTRL_ALT: bool = cfg!(windows);
+
+/// Whether a key's text reaches the screen (`KeyboardHandler.textInput`, then
+/// `charTyped` per code point). The edit modifier's shortcuts type nothing,
+/// but `textInput` takes no modifiers: with AltGr held (Ctrl plus Alt where
+/// `altgr_is_ctrl_alt`) the layout's third-level characters are text, as `/`
+/// on ABNT2, `@`, `{` and `[` on German or the Polish letters.
+pub fn types_text(edit_modifier: bool, alt: bool, altgr_is_ctrl_alt: bool) -> bool {
+    !edit_modifier || (altgr_is_ctrl_alt && alt)
+}
+
 /// `StringUtil.isAllowedChatCharacter`.
 pub fn is_allowed_chat_character(c: char) -> bool {
     c != '§' && c >= ' ' && c != '\u{7f}'
@@ -303,6 +316,22 @@ pub fn append_limited(value: &mut String, text: &str, max_chars: usize) -> bool
 mod tests {
     use super::*;
 
+    #[test]
+    fn altgr_types_text_where_it_is_ctrl_alt() {
+        // Plain keys and Shift type.
+        assert!(types_text(false, false, true));
+        assert!(types_text(false, false, false));
+        // Ctrl (Cmd) shortcuts do not.
+        assert!(!types_text(true, false, true));
+        assert!(!types_text(true, false, false));
+        // AltGr on Windows is Ctrl+Alt: ABNT2 `/`, German `@` type.
+        assert!(types_text(true, true, true));
+        // Where AltGr is its own modifier, Ctrl+Alt is a shortcut.
+        assert!(!types_text(true, true, false));
+        // Alt alone (macOS Option, Linux AltGr) types.
+        assert!(types_text(false, true, false));
+    }
+
     #[test]
     fn shortcuts_need_the_edit_modifier_alone() {
         let c = Some('c');

crates/horizon-client-input/src/keybinds.rs

@@ -300,9 +300,8 @@ impl Default for KeyBinds {
     }
 }
 /// Each default key once, in order: two mappings that share a default key
-/// (Advancements and the debug profiler both on L) are one press of it, not
-/// two (the second would close the screen the first opened). Vanilla clicks
-/// both mappings, but the profiler one only acts with F3 held.
+/// (Pick Block and the spectator hotbar both on the middle button) are one
+/// press of it, not two.
 fn distinct<T: PartialEq>(keys: Vec<T>) -> Vec<T> {
     let mut out = Vec::with_capacity(keys.len());
     for k in keys {
@@ -368,6 +367,25 @@ impl KeyBinds {
             .map(|m| m.0)
             .filter(move |n| self.get(n) == key)
     }
+    /// The mappings bound to `key` that [`KeyBinds::translate_all`] follows:
+    /// all but the debug keys. Those act only with F3 held
+    /// (`KeyboardHandler.handleDebugKeys`, `debug_keys.rs` reads the physical
+    /// key and the binding itself); their defaults (A, S, D, T, L, 1 to 4...)
+    /// would otherwise turn the key back into its old gameplay meaning.
+    fn translated_mappings<'a>(&'a self, key: &'a str) -> impl Iterator<Item = &'static str> + 'a {
+        MAPPINGS
+            .iter()
+            .filter(|m| m.2 != "debug")
+            .map(|m| m.0)
+            .filter(move |n| self.get(n) == key)
+    }
+    /// Whether a mapping (other than a debug key) whose default is `key` was
+    /// bound elsewhere.
+    fn default_moved(&self, key: &str) -> bool {
+        MAPPINGS
+            .iter()
+            .any(|(n, d, c)| *d == key && *c != "debug" && !self.is_default(n))
+    }
     /// Translate a physical key into the default key of the mapping it is
     /// bound to, so game code written against vanilla defaults follows the
     /// player's bindings. `None` means the key now does nothing; mouse
@@ -384,7 +402,7 @@ impl KeyBinds {
             return vec![Ok(key)];
         };
         let bound: Vec<_> = self
-            .mappings_for(name)
+            .translated_mappings(name)
             .filter_map(|mapping| {
                 let default = Self::default_of(mapping);
                 match key_code(default) {
@@ -397,10 +415,7 @@ impl KeyBinds {
             return distinct(bound);
         }
         // An unbound key whose default meaning was moved elsewhere is inert.
-        if MAPPINGS
-            .iter()
-            .any(|(n, d, _)| *d == name && !self.is_default(n))
-        {
+        if self.default_moved(name) {
             return Vec::new();
         }
         vec![Ok(key)]
@@ -413,7 +428,7 @@ impl KeyBinds {
     pub fn translate_mouse_all(&self, button: MouseButton) -> Vec<Result<KeyCode, MouseButton>> {
         let name = mouse_name(button);
         let bound: Vec<_> = self
-            .mappings_for(&name)
+            .translated_mappings(&name)
             .filter_map(|mapping| {
                 let default = Self::default_of(mapping);
                 match mouse_button(default) {
@@ -425,10 +440,7 @@ impl KeyBinds {
         if !bound.is_empty() {
             return distinct(bound);
         }
-        if MAPPINGS
-            .iter()
-            .any(|(n, d, _)| *d == name && !self.is_default(n))
-        {
+        if self.default_moved(&name) {
             return Vec::new();
         }
         vec![Err(button)]
@@ -508,6 +520,29 @@ mod tests {
         assert_eq!(k.conflicts("key.forward"), ["key.jump"]);
     }
     #[test]
+    fn a_moved_key_keeps_no_default_action() {
+        // #3158: the debug keys (F3+A, F3+1...) share these keys' defaults,
+        // and must not hand them back their gameplay meaning.
+        let mut k = KeyBinds::default();
+        k.set("key.hotbar.1", "key.keyboard.q");
+        assert_eq!(k.translate_all(KeyCode::Digit1), []);
+        assert_eq!(
+            k.translate_all(KeyCode::KeyQ),
+            [Ok(KeyCode::KeyQ), Ok(KeyCode::Digit1)]
+        );
+        k.set("key.inventory", "key.keyboard.a");
+        k.set("key.left", "key.keyboard.e");
+        assert_eq!(k.translate_all(KeyCode::KeyA), [Ok(KeyCode::KeyE)]);
+        assert_eq!(k.translate_all(KeyCode::KeyE), [Ok(KeyCode::KeyA)]);
+        k.set("key.back", "key.keyboard.down");
+        assert_eq!(k.translate_all(KeyCode::KeyS), []);
+        // Keys left alone still act, and a moved debug key changes nothing.
+        k.set("key.debug.fpsCharts", "key.keyboard.9");
+        assert_eq!(k.translate_all(KeyCode::Digit2), [Ok(KeyCode::Digit2)]);
+        assert_eq!(k.translate_all(KeyCode::Digit9), [Ok(KeyCode::Digit9)]);
+        assert_eq!(k.translate_all(KeyCode::F3), [Ok(KeyCode::F3)]);
+    }
+    #[test]
     fn display_names() {
         assert_eq!(display_name("key.keyboard.w").plain(), "W");
         assert_eq!(display_name("key.keyboard.slash").plain(), "/");

crates/horizon-client-render/examples/compositor.rs

@@ -0,0 +1,151 @@
+//! Two offscreen frames presented in one window, without game resources or player data.
+//! `cargo run --profile fast -p horizon-client-render --example compositor -- --smoke`
+use horizon_client_render::gfx::compositor::Compositor;
+use std::sync::Arc;
+use winit::{
+    application::ApplicationHandler,
+    event::WindowEvent,
+    event_loop::{ActiveEventLoop, EventLoop},
+    window::{Window, WindowId},
+};
+
+struct Frames {
+    window: Arc<Window>,
+    compositor: Compositor,
+    textures: [wgpu::Texture; 2],
+}
+
+impl Frames {
+    fn new(event_loop: &ActiveEventLoop) -> horizon_client_render::Result<Self> {
+        let window = Arc::new(
+            event_loop.create_window(
+                Window::default_attributes()
+                    .with_title("Compositor: red and blue views")
+                    .with_inner_size(winit::dpi::PhysicalSize::new(640, 360)),
+            )?,
+        );
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_with_display_handle(
+            Box::new(window.clone()),
+        ));
+        let surface = instance.create_surface(window.clone())?;
+        let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
+            compatible_surface: Some(&surface),
+            ..Default::default()
+        }))?;
+        let (device, queue) = pollster::block_on(adapter.request_device(&Default::default()))?;
+        let textures = [[0, 0, 255, 255], [255, 0, 0, 255]].map(|pixel| {
+            let size = wgpu::Extent3d {
+                width: 320,
+                height: 360,
+                depth_or_array_layers: 1,
+            };
+            let texture = device.create_texture(&wgpu::TextureDescriptor {
+                label: Some("Offscreen view"),
+                size,
+                mip_level_count: 1,
+                sample_count: 1,
+                dimension: wgpu::TextureDimension::D2,
+                format: wgpu::TextureFormat::Bgra8Unorm,
+                usage: wgpu::TextureUsages::COPY_SRC | wgpu::TextureUsages::COPY_DST,
+                view_formats: &[],
+            });
+            queue.write_texture(
+                texture.as_image_copy(),
+                &pixel.repeat(320 * 360),
+                wgpu::TexelCopyBufferLayout {
+                    offset: 0,
+                    bytes_per_row: Some(320 * 4),
+                    rows_per_image: Some(360),
+                },
+                size,
+            );
+            texture
+        });
+        let compositor = Compositor::new(
+            surface,
+            &adapter,
+            &device,
+            &queue,
+            window.inner_size().into(),
+        )?;
+        Ok(Self {
+            window,
+            compositor,
+            textures,
+        })
+    }
+}
+
+#[derive(Default)]
+struct Demo {
+    frames: Option<Frames>,
+    error: Option<String>,
+    presented: usize,
+    smoke: bool,
+}
+
+impl ApplicationHandler for Demo {
+    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
+        if self.frames.is_none() {
+            match Frames::new(event_loop) {
+                Ok(frames) => self.frames = Some(frames),
+                Err(error) => {
+                    self.error = Some(error.to_string());
+                    event_loop.exit();
+                }
+            }
+        }
+    }
+
+    fn window_event(&mut self, event_loop: &ActiveEventLoop, _: WindowId, event: WindowEvent) {
+        let Some(f) = &mut self.frames else { return };
+        match event {
+            WindowEvent::CloseRequested => event_loop.exit(),
+            WindowEvent::Resized(size) => f.compositor.resize(size.width, size.height),
+            // Uncovered pixels are black; resize smaller to exercise clipping.
+            WindowEvent::RedrawRequested
+                if f.compositor
+                    .present(&[(&f.textures[0], [0, 0]), (&f.textures[1], [320, 0])]) =>
+            {
+                self.presented += 1;
+                if self.smoke && self.presented == 10 {
+                    f.compositor.set_vsync(false);
+                    f.compositor.resize(0, 0);
+                    assert!(!f.compositor.present(&[]));
+                    f.compositor.resize(u32::MAX, u32::MAX);
+                    assert!(!f.compositor.present(&[]));
+                    f.compositor.resize(400, 240);
+                    let _ = f
+                        .window
+                        .request_inner_size(winit::dpi::PhysicalSize::new(400, 240));
+                }
+                if self.smoke && self.presented == 20 {
+                    println!("compositor: 20 frames, resize, suspension and clipping passed");
+                    event_loop.exit();
+                }
+            }
+            _ => {}
+        }
+    }
+
+    fn about_to_wait(&mut self, _: &ActiveEventLoop) {
+        if let Some(f) = &self.frames {
+            f.window.request_redraw();
+        }
+    }
+}
+
+fn main() -> horizon_client_render::Result<()> {
+    let mut demo = Demo {
+        smoke: std::env::args().any(|a| a == "--smoke"),
+        ..Default::default()
+    };
+    EventLoop::new()?.run_app(&mut demo)?;
+    if let Some(error) = demo.error {
+        return Err(error.into());
+    }
+    if demo.smoke && demo.presented < 20 {
+        return Err("smoke test closed early".into());
+    }
+    Ok(())
+}

crates/horizon-client-render/src/biome.rs

@@ -256,6 +256,10 @@ impl Biomes {
             .copied()
             .unwrap_or(0)
     }
+    /// Whether the game has the biome `name`.
+    pub fn contains(&self, name: &str) -> bool {
+        self.index.contains_key(name)
+    }
     pub fn get(&self, id: u16) -> &BiomeInfo {
         &self.list[usize::from(id).min(self.list.len() - 1)]
     }

crates/horizon-client-render/src/block_entity_render.rs

@@ -654,10 +654,20 @@ fn sign_text_calls(
         .collect()
 }
 
+/// How far the text of an outlined call sits in front of its outline, in
+/// text units (`Font.DisplayMode.POLYGON_OFFSET`, see `draw_text`).
+const TEXT_OVER_OUTLINE: f32 = 0.05;
+
 /// Draws a text call with the font atlas: 8x8 glyph cells, the outline as
 /// eight one-pixel offsets under the text.
+///
+/// `TextFeatureRenderer.renderText` draws the outline glyphs NORMAL and the
+/// text over them POLYGON_OFFSET, so the coplanar text always wins the depth
+/// test. Here both share one mesh, so the text is lifted a hair towards the
+/// reader instead (a twentieth of a font pixel, invisible) rather than
+/// z-fighting with the outline under it.
 fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
-    let mut emit = |dx: f32, dy: f32, argb: u32| {
+    let mut emit = |dx: f32, dy: f32, z: f32, argb: u32| {
         let mut x = call.x + dx;
         let y0 = call.y + dy;
         for ch in call.text.chars() {
@@ -672,7 +682,7 @@ fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
                         normal: [0; 4],
                         pos: call
                             .matrix
-                            .transform_point3(Vec3::new(cx, cy, 0.0))
+                            .transform_point3(Vec3::new(cx, cy, z))
                             .to_array(),
                         uv,
                         layer: 0,
@@ -697,10 +707,15 @@ fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
             (0.0, 1.0),
             (1.0, 1.0),
         ] {
-            emit(dx, dy, call.outline);
+            emit(dx, dy, 0.0, call.outline);
         }
     }
-    emit(0.0, 0.0, call.color);
+    let z = if call.outline != 0 {
+        TEXT_OVER_OUTLINE
+    } else {
+        0.0
+    };
+    emit(0.0, 0.0, z, call.color);
 }
 
 /// Block-entity fields the level ticks, at one position (vanilla's own field
@@ -2258,6 +2273,69 @@ mod tests {
         assert_eq!(out[2].uv, [0.5, 0.5]);
     }
 
+    /// TextFeatureRenderer.renderText: an outlined call's text is drawn over
+    /// its outline (Font.DisplayMode.POLYGON_OFFSET), never level with it,
+    /// and plain text stays on the sign's plane.
+    #[test]
+    fn outlined_sign_text_sits_in_front_of_its_outline() {
+        let world = World::new(BlockStateId(0), 1);
+        let sprites = HashMap::new();
+        let glyph = |_: char| {
+            let rect = Rect {
+                u0: 0.0,
+                v0: 0.0,
+                u1: 0.0625,
+                v1: 0.0625,
+                w: 8,
+                h: 8,
+            };
+            (Some(rect), 6.0)
+        };
+        let scene = Scene {
+            camera: DVec3::ZERO,
+            orientation: Quat::IDENTITY,
+            anim: &|_| BlockAnim::default(),
+            texts: None,
+            partial: 0.0,
+            game_time: 0,
+            max_y: 320,
+            world: &world,
+            sprites: &sprites,
+            nether: false,
+            lid: &|_| 0.0,
+            sign: &|_| None,
+            banner: &|_| Vec::new(),
+            skull: &|_| None,
+            glyph: &glyph,
+            glyphs: 0,
+        };
+        let mut call = TextCall {
+            matrix: Mat4::IDENTITY,
+            x: 0.0,
+            y: 0.0,
+            text: "Hi".into(),
+            color: 0xFFFF_FF00,
+            outline: 0xFF33_3300,
+            light: 240 | 240 << 8,
+        };
+        let mut out = Vec::new();
+        draw_text(&scene, &call, &mut out);
+        // Eight outline copies, then the text, four corners a glyph.
+        assert_eq!(out.len(), 9 * 2 * 4);
+        let (outline, text) = out.split_at(8 * 2 * 4);
+        let front = outline.iter().map(|v| v.pos[2]).fold(f32::MIN, f32::max);
+        assert!(
+            text.iter().all(|v| v.pos[2] > front),
+            "text z {:?} not in front of the outline at {front}",
+            text.iter().map(|v| v.pos[2]).collect::<Vec<_>>()
+        );
+        call.outline = 0;
+        out.clear();
+        draw_text(&scene, &call, &mut out);
+        assert_eq!(out.len(), 2 * 4);
+        assert!(out.iter().all(|v| v.pos[2] == 0.0));
+    }
+
     #[test]
     fn cached_sign_text_matches_and_follows_changes() {
         let renderer = BlockEntityRenderer {

crates/horizon-client-render/src/brewing.rs

@@ -50,20 +50,30 @@ pub fn tooltip(
             Category::Neutral,
         )];
     }
-    def.effects
-        .iter()
+    effect_lines(def.effects.iter().copied(), scale, translate)
+}
+/// `PotionContents.addPotionTooltip`'s line per effect: its name, potency and
+/// scaled duration, for (effect id, duration, amplifier) entries.
+pub fn effect_lines<'a>(
+    effects: impl IntoIterator<Item = (&'a str, i32, i32)>,
+    scale: f32,
+    translate: &dyn Fn(&str) -> Option<String>,
+) -> Vec<(String, Category)> {
+    effects
+        .into_iter()
         .map(|(e, duration, amp)| {
+            let e = e.trim_start_matches("minecraft:");
             let mut line =
-                translate(&format!("effect.minecraft.{e}")).unwrap_or_else(|| (*e).to_owned());
-            if *amp > 0 {
+                translate(&format!("effect.minecraft.{e}")).unwrap_or_else(|| e.to_owned());
+            if amp > 0 {
                 line.push(' ');
                 line.push_str(
                     &translate(&format!("potion.potency.{amp}"))
-                        .unwrap_or_else(|| crate::enchant::level_name(*amp as u32 + 1)),
+                        .unwrap_or_else(|| crate::enchant::level_name(amp as u32 + 1)),
                 );
             }
             let instant = effect(e).is_some_and(|d| d.instant);
-            let scaled = (*duration as f32 * scale) as i32;
+            let scaled = (duration as f32 * scale) as i32;
             if !instant && scaled > 20 {
                 line = format!("{line} ({})", format_duration(scaled));
             }
@@ -386,4 +396,23 @@ mod tests {
         stand.tick(&brewing, &items, &providers);
         assert_eq!(stand.brew_time, 0);
     }
+
+    /// #3312: `PotionContents.getPotionDescription` names the effects with
+    /// translatable components, so a Russian game reads them from ru_ru.json
+    /// (the prepared one; skipped without it), as the tooltip's other lines.
+    #[test]
+    fn effect_lines_read_the_selected_language() {
+        let root = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+            .join("../../.local/horizon-client")
+            .join(horizon_core::VANILLA_VERSION);
+        if !root.join("assets/minecraft/lang/ru_ru.json").exists() {
+            return;
+        }
+        let ru = crate::lang::Language::load(&[&root], "ru_ru");
+        let translate = |key: &str| ru.get(key).map(str::to_owned);
+        let lines = tooltip(Some("minecraft:turtle_master"), 0.125, &translate);
+        assert_eq!(lines.len(), 2);
+        assert!(lines[0].0.starts_with("Замедление IV ("), "{lines:?}");
+        assert!(lines[1].0.starts_with("Сопротивление III ("), "{lines:?}");
+    }
 }

crates/horizon-client-render/src/crash.rs

@@ -3,6 +3,7 @@
 //! Written to `crash-reports/crash-<yyyy-MM-dd_HH.mm.ss>-client.txt` in the game folder when
 //! the main thread panics or `main` gets an error back. It leaves the machine only scrubbed, and
 //! only if the player allows crash reports (`telemetry`).
+use std::cell::{Cell, RefCell};
 use std::fmt::Write as _;
 use std::path::{Path, PathBuf};
 use std::sync::Mutex;
@@ -14,6 +15,51 @@ use chrono::{DateTime, Local};
 static DETAILS: Mutex<Vec<(&'static str, String)>> = Mutex::new(Vec::new());
 static REPORTED: AtomicBool = AtomicBool::new(false);
 
+thread_local! {
+    /// How many `contain` calls this thread is inside.
+    static CONTAINED: Cell<u32> = const { Cell::new(0) };
+    /// The message of the last panic `contain` caught on this thread, from the hook.
+    static CAUGHT: RefCell<Option<String>> = const { RefCell::new(None) };
+}
+
+/// Runs `f`, and returns a panic in it as an error with the panic's message instead of letting
+/// it end the game. For work that is not the game's own and whose failure the caller recovers
+/// from, such as handing a shader pack's programs to the GPU driver's compiler: the panic goes
+/// to the log with its stack, and no crash report is made for it.
+pub fn contain<T>(f: impl FnOnce() -> T) -> Result<T, String> {
+    CONTAINED.with(|c| c.set(c.get() + 1));
+    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(f));
+    CONTAINED.with(|c| c.set(c.get() - 1));
+    result.map_err(|payload| {
+        CAUGHT
+            .with(|c| c.borrow_mut().take())
+            .unwrap_or_else(|| payload_text(&*payload))
+    })
+}
+
+/// For the hook: a panic inside `contain` is logged with its stack and kept for `contain` to
+/// return. False for any other panic.
+fn contained_panic(info: &std::panic::PanicHookInfo) -> bool {
+    if CONTAINED.with(Cell::get) == 0 {
+        return false;
+    }
+    let message = panic_message(info);
+    let stack = stack_lines(
+        &std::backtrace::Backtrace::force_capture().to_string(),
+        true,
+    );
+    log::error!(
+        "Recovered from an error: {message}\n{}",
+        stack
+            .lines()
+            .map(|l| format!("\tat {l}"))
+            .collect::<Vec<_>>()
+            .join("\n")
+    );
+    CAUGHT.with(|c| *c.borrow_mut() = Some(message));
+    true
+}
+
 /// Sets one line of the report's details (replacing the last value under `key`).
 pub fn set_detail(key: &'static str, value: impl Into<String>) {
     let mut details = DETAILS.lock().unwrap_or_else(|e| e.into_inner());
@@ -308,13 +354,35 @@ fn deliver(home: &Path, report: Report) -> Option<PathBuf> {
     }
 }
 
-fn panic_message(info: &std::panic::PanicHookInfo) -> String {
-    let payload = info.payload();
-    let text = payload
+/// The report for a hung server tick, written by the watchdog thread
+/// (`ServerWatchdog`): the stuck thread's stack is not available to Rust, so
+/// the report carries none.
+pub fn report_watchdog(home: &Path, side: &'static str, message: String) -> Option<PathBuf> {
+    deliver(
+        home,
+        Report {
+            time: Local::now(),
+            description: "Watching Server".into(),
+            error: format!("{message} (Watching Server)"),
+            stack: String::new(),
+            thread: thread_name(),
+            side,
+            details: system_details(),
+            log: crate::logging::recent_lines(),
+        },
+    )
+}
+
+fn payload_text(payload: &(dyn std::any::Any + Send)) -> String {
+    payload
         .downcast_ref::<&str>()
         .map(|s| s.to_string())
         .or_else(|| payload.downcast_ref::<String>().cloned())
-        .unwrap_or_else(|| "Box<dyn Any>".into());
+        .unwrap_or_else(|| "Box<dyn Any>".into())
+}
+
+fn panic_message(info: &std::panic::PanicHookInfo) -> String {
+    let text = payload_text(info.payload());
     match info.location() {
         Some(at) => format!("panicked at {at}:\n{text}"),
         None => format!("panicked:\n{text}"),
@@ -417,10 +485,13 @@ pub fn panic_report(info: &std::panic::PanicHookInfo, side: &'static str) -> Rep
 
 /// Reports panics: on the main thread a crash report (the panic then ends the game, exit code
 /// 101); on other threads the error goes to the log, as vanilla's uncaught exception handler
-/// does. The default hook still prints the panic.
+/// does. The default hook still prints the panic. A panic inside `contain` is only logged.
 pub fn install(home: PathBuf, side: &'static str) {
     let default = std::panic::take_hook();
     std::panic::set_hook(Box::new(move |info| {
+        if contained_panic(info) {
+            return;
+        }
         default(info);
         let main = std::thread::current().name() == Some("main");
         if main {
@@ -609,6 +680,17 @@ mod tests {
         );
     }
 
+    #[test]
+    fn contained_panics_come_back_as_errors() {
+        assert_eq!(contain(|| 7), Ok(7));
+        let error = contain(|| -> u8 { panic!("a pack's program") }).unwrap_err();
+        assert!(error.contains("a pack's program"), "{error}");
+        // Nested, and the thread is no longer inside one after.
+        let outer = contain(|| contain(|| -> u8 { panic!("inner") }));
+        assert!(outer.unwrap().unwrap_err().contains("inner"));
+        assert_eq!(CONTAINED.with(Cell::get), 0);
+    }
+
     #[test]
     fn the_debug_crash_is_reported_as_vanillas() {
         let error: Box<dyn std::error::Error> = DebugCrash::new().into();

crates/horizon-client-render/src/datapack.rs

@@ -2,7 +2,10 @@
 //! the parts of them commands use: `.mcfunction` functions (with macros and
 //! line continuation), function tags and predicates.
 use crate::zip::Zip;
-use horizon_world::nbt::Tag;
+use horizon_world::{
+    nbt::Tag,
+    worldgen::overrides::{self, PackFile, WorldgenOverrides},
+};
 use std::{
     collections::BTreeMap,
     path::{Path, PathBuf},
@@ -125,6 +128,114 @@ pub fn discover(world: &Path) -> Vec<DataPack> {
     packs
 }
 
+// ---- Create World ------------------------------------------------------------
+
+/// Create World's Data Packs screen (`PackSelectionScreen` on vanilla's
+/// `mcworld-` folder): the folder's packs (`PackSource.WORLD`) and the
+/// built-in one (`resources` holds its `pack.png`), which can be unselected
+/// and stays at the bottom. Horizon has no experiments, so their feature
+/// packs are not offered.
+pub fn screen_packs(dir: &Path, resources: &Path) -> Vec<crate::pack_screen::PackInfo> {
+    use crate::{
+        pack_screen::{Compat, PackInfo, Source, load_icon},
+        packs::Position,
+        text::{Style, Text},
+    };
+    let format = horizon_core::version::DATA_PACK_FORMAT;
+    let mut infos: Vec<PackInfo> = crate::packs::folder(dir, format)
+        .into_iter()
+        .map(|p| PackInfo {
+            icon: p.icon_png().as_deref().and_then(load_icon),
+            id: p.id,
+            title: p.title,
+            description: p.raw_description,
+            description_style: p.description_style,
+            source: Source::World,
+            compat: p.compatibility,
+            required: false,
+            position: Position::Top,
+            fixed: false,
+        })
+        .collect();
+    infos.push(PackInfo {
+        id: "vanilla".into(),
+        title: Text::translate("dataPack.vanilla.name", &[]),
+        description: Text::translate("dataPack.vanilla.description", &[]),
+        description_style: Style::default(),
+        source: Source::BuiltIn,
+        compat: Compat::Compatible,
+        icon: std::fs::read(resources.join("pack.png"))
+            .ok()
+            .as_deref()
+            .and_then(load_icon),
+        required: false,
+        position: Position::Bottom,
+        fixed: false,
+    });
+    infos
+}
+/// A new empty folder for Create World's packs
+/// (`Files.createTempDirectory("mcworld-")`).
+pub fn temp_folder() -> std::io::Result<PathBuf> {
+    let nanos = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_nanos();
+    let dir = std::env::temp_dir().join(format!("mcworld-{}-{nanos}", std::process::id()));
+    std::fs::create_dir_all(&dir)?;
+    Ok(dir)
+}
+/// What's in a folder of packs, to notice packs added or removed while the
+/// screen shows it (`PackSelectionScreen.Watcher`).
+pub fn folder_stamp(dir: &Path) -> Vec<(String, Option<std::time::SystemTime>)> {
+    let mut stamp: Vec<_> = std::fs::read_dir(dir)
+        .into_iter()
+        .flatten()
+        .flatten()
+        .map(|e| {
+            let modified = e.metadata().and_then(|m| m.modified()).ok();
+            (e.file_name().to_string_lossy().into_owned(), modified)
+        })
+        .collect();
+    stamp.sort();
+    stamp
+}
+/// Create World's packs into the new world before it opens
+/// (`copyTempDataPackDirToNewWorld`): every pack of `dir` goes to
+/// `<world>/datapacks`, and `datapacks.json` enables those `selected`
+/// (lowest priority first) and disables the rest.
+pub fn install(dir: &Path, world: &Path, selected: &[String]) -> Result<(), String> {
+    let err = |p: &Path, e: std::io::Error| format!("{}: {e}", p.display());
+    let target = world.join("datapacks");
+    std::fs::create_dir_all(&target).map_err(|e| err(&target, e))?;
+    let mut disabled = Vec::new();
+    for pack in crate::packs::folder(dir, horizon_core::version::DATA_PACK_FORMAT) {
+        let (crate::packs::Source::Dir(from) | crate::packs::Source::Zip(from)) = &pack.source;
+        copy(from, &target.join(pack.id.trim_start_matches("file/")))?;
+        if !selected.contains(&pack.id) {
+            disabled.push(pack.id);
+        }
+    }
+    if !selected.iter().any(|id| id == "vanilla") {
+        disabled.push("vanilla".into());
+    }
+    let json = serde_json::json!({ "enabled": selected, "disabled": disabled });
+    let file = world.join("datapacks.json");
+    std::fs::write(&file, json.to_string()).map_err(|e| err(&file, e))
+}
+/// A file, or a folder and everything in it.
+fn copy(from: &Path, to: &Path) -> Result<(), String> {
+    let err = |e: std::io::Error| format!("{} -> {}: {e}", from.display(), to.display());
+    if !from.is_dir() {
+        return std::fs::copy(from, to).map(drop).map_err(err);
+    }
+    std::fs::create_dir_all(to).map_err(err)?;
+    for e in std::fs::read_dir(from).map_err(err)?.flatten() {
+        copy(&e.path(), &to.join(e.file_name()))?;
+    }
+    Ok(())
+}
+
 // ---- functions ---------------------------------------------------------------
 
 /// A `.mcfunction`: plain command lines and macro lines.
@@ -421,9 +532,138 @@ fn hash_normalize(s: &str) -> String {
     }
 }
 
+/// The ids of `packs` (a world's, from `discover`) that are enabled, lowest
+/// priority first: those `<world>/datapacks.json` lists as enabled, in its
+/// order, then every pack it lists neither way, in name order.
+pub fn enabled_ids(world: &Path, packs: &[DataPack]) -> Vec<String> {
+    let saved: Option<serde_json::Value> = std::fs::read(world.join("datapacks.json"))
+        .ok()
+        .and_then(|b| serde_json::from_slice(&b).ok());
+    let list = |key: &str| -> Vec<String> {
+        saved
+            .as_ref()
+            .and_then(|v| v[key].as_array())
+            .map(|a| {
+                a.iter()
+                    .filter_map(|s| s.as_str().map(str::to_owned))
+                    .collect()
+            })
+            .unwrap_or_default()
+    };
+    let disabled = list("disabled");
+    let mut enabled: Vec<String> = list("enabled")
+        .into_iter()
+        .filter(|id| packs.iter().any(|p| &p.id == id))
+        .collect();
+    for p in packs {
+        if !enabled.contains(&p.id) && !disabled.contains(&p.id) {
+            enabled.push(p.id.clone());
+        }
+    }
+    enabled
+}
+
+// ---- worldgen ----------------------------------------------------------------
+
+/// The worldgen entries of `packs` (lowest priority first, the built-in pack
+/// left out: the prepared bundles are it) for the chunk generator, and what
+/// it leaves out, for the log. `biomes` says which biomes the game has: a
+/// pack's new biome is left out (the game has no colours, sounds or id for it).
+pub fn worldgen_overrides(
+    packs: &[&DataPack],
+    biomes: impl Fn(&str) -> bool,
+) -> (WorldgenOverrides, Vec<String>) {
+    let mut out = WorldgenOverrides::default();
+    let mut not_read: BTreeMap<String, usize> = BTreeMap::new();
+    let mut warnings = Vec::new();
+    for pack in packs {
+        for file in pack.list_kinds(&overrides::PACK_KINDS) {
+            let read = || String::from_utf8(pack.read(&file)?).ok();
+            match out.add_file(&pack.id, &file, read) {
+                PackFile::Read | PackFile::Other => {}
+                PackFile::DimensionType { id, min_y, height } => warnings.push(format!(
+                    "{}: dimension type {id} (min_y {min_y}, height {height}) is not used: \
+                     the dimension keeps its vanilla build height",
+                    pack.id
+                )),
+                PackFile::NotRead(kind) => {
+                    *not_read.entry(format!("{}: {kind}", pack.id)).or_default() += 1
+                }
+                PackFile::Unreadable => warnings.push(format!("{}: {file}: unreadable", pack.id)),
+            }
+        }
+    }
+    warnings.extend(out.finish(biomes));
+    for (kind, files) in not_read {
+        warnings.push(format!("{kind}: {files} files the generator does not read"));
+    }
+    (out, warnings)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    #[test]
+    fn enabled_packs_override_worldgen_in_order() {
+        let dir = std::env::temp_dir().join(format!("hz-datapack-worldgen-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        let write = |pack: &str, p: &str, t: &str| {
+            let path = dir.join("datapacks").join(pack).join(p);
+            std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+            std::fs::write(path, t).unwrap();
+        };
+        for pack in ["a", "b", "off"] {
+            write(pack, "pack.mcmeta", "{}");
+            write(pack, "data/minecraft/worldgen/noise/cave.json", pack);
+            write(
+                pack,
+                "data/minecraft/tags/worldgen/biome/is_hill.json",
+                "{\"values\":[]}",
+            );
+        }
+        write("a", "data/minecraft/worldgen/biome/new_peaks.json", "{}");
+        write("a", "data/minecraft/worldgen/biome/plains.json", "{}");
+        write(
+            "a",
+            "data/minecraft/worldgen/world_preset/normal.json",
+            "{}",
+        );
+        write(
+            "b",
+            "data/minecraft/dimension_type/overworld.json",
+            "{\"min_y\":-64,\"height\":2096}",
+        );
+        // `b` is enabled first, so `a` (enabled after it) wins.
+        std::fs::write(
+            dir.join("datapacks.json"),
+            "{\"enabled\":[\"file/b\",\"file/a\"],\"disabled\":[\"file/off\"]}",
+        )
+        .unwrap();
+        let packs = discover(&dir);
+        let enabled = enabled_ids(&dir, &packs);
+        assert_eq!(enabled, ["file/b", "file/a"]);
+        let enabled: Vec<&DataPack> = enabled
+            .iter()
+            .map(|id| packs.iter().find(|p| &p.id == id).unwrap())
+            .collect();
+        let (o, warnings) = worldgen_overrides(&enabled, |b| b == "minecraft:plains");
+        assert_eq!(
+            o.entries("noises").collect::<Vec<_>>(),
+            [("minecraft:cave", "a")]
+        );
+        assert_eq!(
+            o.entries("biomes").collect::<Vec<_>>(),
+            [("minecraft:plains", "{}")]
+        );
+        let tag_packs: Vec<&str> = o.tags("biome_tags").map(|(_, p, _)| p).collect();
+        assert_eq!(tag_packs, ["file/b", "file/a"]);
+        assert_eq!(warnings.len(), 3, "{warnings:?}");
+        assert!(warnings[0].contains("height 2096"));
+        assert!(warnings[1].contains("minecraft:new_peaks"));
+        assert!(warnings[2].contains("worldgen/world_preset"));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
     use horizon_world::nbt::parse_snbt;
 
     #[test]
@@ -566,4 +806,51 @@ mod tests {
         assert_eq!(p.list_kinds(&kinds), wanted);
         let _ = std::fs::remove_dir_all(&dir);
     }
+
+    #[test]
+    fn create_world_installs_its_packs() {
+        let root = std::env::temp_dir().join(format!("hz-datapack-install-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&root);
+        let (dir, world) = (root.join("mcworld"), root.join("world"));
+        let write = |pack: &str, p: &str, t: &str| {
+            let path = dir.join(pack).join(p);
+            std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+            std::fs::write(path, t).unwrap();
+        };
+        write("fns", "pack.mcmeta", r#"{"pack":{"pack_format":121}}"#);
+        write("fns", "data/x/function/f.mcfunction", "say hi");
+        write("off", "pack.mcmeta", r#"{"pack":{"pack_format":121}}"#);
+        std::fs::create_dir_all(&dir).unwrap();
+        let mut zip = zip::ZipWriter::new(std::fs::File::create(dir.join("old.zip")).unwrap());
+        zip.start_file("pack.mcmeta", zip::write::SimpleFileOptions::default())
+            .unwrap();
+        std::io::Write::write_all(&mut zip, br#"{"pack":{"pack_format":48}}"#).unwrap();
+        zip.finish().unwrap();
+        let infos = screen_packs(&dir, &root);
+        let ids: Vec<&str> = infos.iter().map(|p| p.id.as_str()).collect();
+        assert_eq!(ids, ["file/fns", "file/off", "file/old.zip", "vanilla"]);
+        let compat: Vec<_> = infos.iter().map(|p| p.compat).collect();
+        use crate::pack_screen::Compat;
+        assert_eq!(
+            compat,
+            [
+                Compat::Compatible,
+                Compat::Compatible,
+                Compat::TooOld,
+                Compat::Compatible
+            ]
+        );
+        let selected = ["vanilla", "file/old.zip", "file/fns"].map(String::from);
+        install(&dir, &world, &selected).unwrap();
+        let packs = discover(&world);
+        let ids: Vec<&str> = packs.iter().map(|p| p.id.as_str()).collect();
+        assert_eq!(ids, ["file/fns", "file/off", "file/old.zip"]);
+        let saved: serde_json::Value =
+            serde_json::from_slice(&std::fs::read(world.join("datapacks.json")).unwrap()).unwrap();
+        assert_eq!(
+            saved,
+            serde_json::json!({"enabled": selected, "disabled": ["file/off"]})
+        );
+        let _ = std::fs::remove_dir_all(&root);
+    }
 }

crates/horizon-client-render/src/fog.rs

@@ -379,6 +379,22 @@ pub fn setup_fog(tables: &FogTables, state: &FogState, input: &FogInputs) -> Fog
     }
     fog
 }
+/// Horizon's Fog option turned off (`horizon-graphics.txt` `fog:false`):
+/// no distance fog, in any dimension: the dimension's and biome's own fog
+/// (`visual/fog_start_distance`, `fog_end_distance`: the Nether's ends at 96
+/// blocks) and the render-distance fog. The fog of the fluid or powder snow
+/// the camera is in, blindness, darkness and a boss's world fog keep their
+/// limits. Vanilla has no such option.
+pub fn clear_distance_fog(fog: &mut FogData, input: &FogInputs) {
+    if input.fog_type == FogType::Atmospheric
+        && input.darkness.is_none()
+        && !input.boss_world_fog
+        && input.blindness.is_none()
+    {
+        (fog.render_distance_start, fog.render_distance_end) = (1e9, 2e9);
+        (fog.environmental_start, fog.environmental_end) = (1e9, 2e9);
+    }
+}
 /// `AtmosphericFogEnvironment.updateRainFogState`.
 pub fn update_rain_fog(
     state: &mut FogState,
@@ -452,6 +468,56 @@ mod tests {
         assert_eq!(water.environmental_start, -8.0);
     }
     #[test]
+    fn fog_off_clears_the_nether_fog_too() {
+        // The Nether's visual/fog_start_distance and fog_end_distance (10, 96)
+        // end before the render distance; the Fog option still clears them.
+        let nether = Sky {
+            fog_start: 10.0,
+            fog_end: 96.0,
+            ..Sky::default()
+        };
+        let tables = FogTables {
+            water_fog_end: vec![1.0],
+        };
+        let mut input = inputs(&nether);
+        input.skybox = false;
+        let mut fog = setup_fog(&tables, &FogState::default(), &input);
+        assert_eq!(fog.environmental_end, 96.0);
+        clear_distance_fog(&mut fog, &input);
+        assert!(fog.environmental_start >= 1e9 && fog.render_distance_start >= 1e9);
+    }
+    #[test]
+    fn fog_off_keeps_fluid_and_effect_fog() {
+        let sky = Sky {
+            fog_start: 10.0,
+            fog_end: 96.0,
+            ..Sky::default()
+        };
+        let tables = FogTables {
+            water_fog_end: vec![1.0],
+        };
+        let kept = |input: &FogInputs| {
+            let mut fog = setup_fog(&tables, &FogState::default(), input);
+            let before = fog;
+            clear_distance_fog(&mut fog, input);
+            fog == before
+        };
+        for fog_type in [FogType::Lava, FogType::PowderSnow, FogType::Water] {
+            let mut input = inputs(&sky);
+            input.fog_type = fog_type;
+            assert!(kept(&input), "{fog_type:?}");
+        }
+        let mut input = inputs(&sky);
+        input.blindness = Some((100, false));
+        assert!(kept(&input));
+        let mut input = inputs(&sky);
+        input.darkness = Some(0.5);
+        assert!(kept(&input));
+        let mut input = inputs(&sky);
+        input.boss_world_fog = true;
+        assert!(kept(&input));
+    }
+    #[test]
     fn boss_darkening_dims_fog_color() {
         // FogRenderer.computeFogColor: lerp toward 70/60/60% of each channel.
         let sky = Sky {

crates/horizon-client-render/src/gfx.rs

@@ -43,6 +43,7 @@ pub use entity_batch::{
     TRANSLUCENT_GLINT_ITEM_OVERLAY, TRANSLUCENT_ITEM_OVERLAY, TRANSLUCENT_PARTICLE_OVERLAY,
     WATER_MASK_OVERLAY,
 };
+pub use view::{View, ViewSet};
 
 /// Window.getAppropriateLineWidth, in framebuffer pixels.
 pub fn outline_width(width: u32) -> f32 {
@@ -69,6 +70,7 @@ pub fn outline_vertices(edges: &[[f64; 6]], camera: glam::DVec3) -> Vec<[f32; 6]
 
 mod animate;
 mod arena;
+pub mod compositor;
 mod cull;
 mod end_sky;
 mod flat;
@@ -92,12 +94,14 @@ pub mod pack_uniforms;
 mod pack_weather;
 mod page_runs;
 pub mod panorama;
+mod readback;
 mod resident;
 mod stars;
 mod sunrise_fan;
 mod timing;
 pub mod translucency;
 pub(crate) mod upload;
+mod view;
 mod wgsl_prefix;
 mod world_post;
 
@@ -566,6 +570,8 @@ pub struct Renderer {
     pub hud: HudRenderer,
     /// Vanilla's menu background blur, made on first use.
     menu_blur: Option<crate::menu_blur::MenuBlur>,
+    /// Where a screenshot's frame is drawn when the swapchain cannot be read back.
+    readback: readback::Readback,
     pub info: wgpu::AdapterInfo,
     pub suspended: bool,
     pub drawn_sections: usize,
@@ -879,6 +885,14 @@ fn check_layers(limits: &wgpu::Limits, layers: u32) -> Result<()> {
     }
     Ok(())
 }
+/// Whether the swapchain can take a window of `width` x `height`: each side from 1 to the
+/// device's `max_texture_dimension_2d` (`max`), else `Surface::configure` panics. 0 is a
+/// minimized window. Past `max`: Windows lets a program size a window up to 65535 pixels
+/// (`SetWindowPos`), a 984x65496 client area, when an RTX 5080 takes 32768. Vanilla's
+/// `Window.onFramebufferResize` likewise keeps the last size for one that is not positive.
+fn drawable_size(width: u32, height: u32, max: u32) -> bool {
+    (1..=max).contains(&width) && (1..=max).contains(&height)
+}
 /// The swapchain format: a non-sRGB target, because vanilla blends and tints in gamma
 /// space, and 8-bit, because wgpu gives `Rgba16Float` the linear `ExtendedSrgb` color
 /// space: the compositor would read these gamma-encoded values as linear light and wash
@@ -1126,9 +1140,14 @@ impl Renderer {
         let info = adapter.get_info();
         crate::graphics::suggest_reduced_far_detail(crate::graphics::lod_capped(&info));
         let size = window.inner_size();
+        let max_side = device.limits().max_texture_dimension_2d;
         let (config, present_modes, hdr_output) = if let Some(surface) = &surface {
             let mut config = surface
-                .get_default_config(&adapter, size.width.max(1), size.height.max(1))
+                .get_default_config(
+                    &adapter,
+                    size.width.clamp(1, max_side),
+                    size.height.clamp(1, max_side),
+                )
                 .ok_or("surface has no supported configuration")?;
             let caps = surface.get_capabilities(&adapter);
             config.format = surface_format(&caps.formats, config.format);
@@ -1167,8 +1186,8 @@ impl Renderer {
             let config = wgpu::SurfaceConfiguration {
                 usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
                 format,
-                width: size.width.max(1),
-                height: size.height.max(1),
+                width: size.width.clamp(1, max_side),
+                height: size.height.clamp(1, max_side),
                 present_mode: wgpu::PresentMode::Immediate,
                 desired_maximum_frame_latency: 2,
                 alpha_mode: wgpu::CompositeAlphaMode::Opaque,
@@ -2709,8 +2728,9 @@ impl Renderer {
             pack_terrain_flat: false,
             hud,
             menu_blur: None,
+            readback: readback::Readback::default(),
             info,
-            suspended: size.width == 0 || size.height == 0,
+            suspended: !drawable_size(size.width, size.height, max_side),
             drawn_sections: 0,
             section_draws: 0,
             section_draw_calls: 0,
@@ -2870,8 +2890,11 @@ impl Renderer {
             );
         }
     }
+    /// Follows the window to `width` x `height`. A size the swapchain can't take
+    /// ([`drawable_size`]) keeps the last one and draws nothing until the next.
     pub fn resize(&mut self, width: u32, height: u32) {
-        self.suspended = width == 0 || height == 0;
+        let max = self.device.limits().max_texture_dimension_2d;
+        self.suspended = !drawable_size(width, height, max);
         if self.suspended {
             return;
         }
@@ -3225,7 +3248,7 @@ impl Renderer {
     ) {
         surface.configure(device, config);
         if let Some(hdr) = hdr {
-            horizon_hdr::set_metadata(device, surface, hdr.paper_white, hdr.peak);
+            horizon_hdr::set_metadata(device, surface, hdr.paper_white, hdr.peak, hdr.black);
         }
     }
     fn configure_surface(&self) {
@@ -3240,7 +3263,7 @@ impl Renderer {
     }
     fn send_hdr_metadata(&self) {
         if let (Some(surface), Some(hdr)) = (&self.surface, &self.hdr) {
-            horizon_hdr::set_metadata(&self.device, surface, hdr.paper_white, hdr.peak);
+            horizon_hdr::set_metadata(&self.device, surface, hdr.paper_white, hdr.peak, hdr.black);
         }
     }
     /// The swapchain's configuration: `config` (what every pipeline draws in), or
@@ -3270,7 +3293,14 @@ impl Renderer {
     }
     /// HDR output (Horizon setting): HDR10 or scRGB at `paper_white` nits, the world's
     /// highlights expanded up to `peak` nits. Off where the surface can't present it.
-    pub fn set_hdr(&mut self, on: bool, paper_white: f32, peak: f32, marker: &std::path::Path) {
+    pub fn set_hdr(
+        &mut self,
+        on: bool,
+        paper_white: f32,
+        peak: f32,
+        black: f32,
+        marker: &std::path::Path,
+    ) {
         let output = self.hdr_output.filter(|_| on && self.surface.is_some());
         if output.is_some() != self.hdr.is_some() {
             // If the game dies before HDR output shows a frame, the marker is still there at
@@ -3294,15 +3324,17 @@ impl Renderer {
             }
         }
         if let Some(hdr) = &mut self.hdr
-            && (hdr.paper_white, hdr.peak) != (paper_white, peak)
+            && (hdr.paper_white, hdr.peak, hdr.black) != (paper_white, peak, black)
         {
             hdr.paper_white = paper_white;
             hdr.peak = peak;
+            hdr.black = black;
             self.send_hdr_metadata();
         }
     }
     /// `upscale`: output pixels per rendered pixel, for TAA to rebuild (1: native).
     pub fn set_world_post(&mut self, scale: f32, antialias: bool, taa: bool, upscale: f32) {
+        let taa = taa && self.world_post.supports_taa();
         self.world_post.scale = scale.clamp(0.25, 2.0);
         self.world_post.antialias = antialias && !taa;
         self.world_post.taa = taa;
@@ -3502,14 +3534,14 @@ impl Renderer {
             &self.lightmap_sampler,
         );
     }
-    pub fn view_projection(&self, frame: &Frame) -> Mat4 {
-        self.projection(
+    /// The views `render` draws `frame` from.
+    pub fn views(&self, frame: &Frame) -> ViewSet {
+        ViewSet::single(self.screen_view(
             frame.fov_degrees,
             frame.yaw,
             frame.pitch,
-            frame.bob * frame.spin,
             frame.depth_far,
-        )
+        ))
     }
     /// The view frustum `render` will cull with, for culling geometry built
     /// before the frame (entities, block entities) the same way.
@@ -3521,13 +3553,14 @@ impl Renderer {
         bob: Mat4,
         depth_far: f32,
     ) -> Frustum {
+        let views = ViewSet::single(self.screen_view(fov_degrees, yaw, pitch, depth_far));
         Frustum {
-            planes: frustum(self.projection(fov_degrees, yaw, pitch, bob, depth_far)),
+            planes: frustum(views.cull().view_proj(bob)),
         }
     }
-    fn projection(&self, fov_degrees: f32, yaw: f32, pitch: f32, bob: Mat4, far: f32) -> Mat4 {
+    fn screen_view(&self, fov_degrees: f32, yaw: f32, pitch: f32, far: f32) -> View {
         let aspect = self.config.width as f32 / self.config.height.max(1) as f32;
-        world_projection(fov_degrees, aspect, far) * bob * crate::camera::view_matrix(yaw, pitch)
+        View::screen(yaw, pitch, fov_degrees, aspect, far)
     }
     fn update_lightmap(
         &mut self,
@@ -3659,7 +3692,12 @@ impl Renderer {
         let size = [self.config.width, self.config.height];
         let target_texture = match (&surface_frame, &mut self.hdr) {
             (Some(_), Some(hdr)) => hdr.frame(&self.device, size),
-            (Some(f), None) => f.texture.clone(),
+            // A screenshot of a swapchain without COPY_SRC (OpenGL) draws
+            // into a texture that has it, then onto the swapchain.
+            (Some(f), None) => self
+                .readback
+                .target(&self.device, &f.texture, self.screenshot.is_some())
+                .unwrap_or_else(|| f.texture.clone()),
             (None, _) => self.offscreen.clone().ok_or("no offscreen target")?,
         };
         // One command buffer for the frame, after the section copies staged
@@ -3687,7 +3725,9 @@ impl Renderer {
             frame.block_flicker,
             frame.boss_darken,
         );
-        let view_proj = self.view_projection(frame);
+        let views = self.views(frame);
+        let pose = frame.bob * frame.spin;
+        let view_proj = views.primary().view_proj(pose);
         // TAA runs where the world post pass does, not under a shader pack's own.
         let taa = !frame.title
             && self.pack_post.as_ref().is_none_or(|p| p.1.is_none())
@@ -3707,8 +3747,7 @@ impl Renderer {
                 frame.pitch,
             );
         }
-        let aspect = self.config.width as f32 / self.config.height.max(1) as f32;
-        let view = crate::camera::view_matrix(frame.yaw, frame.pitch);
+        let view = views.primary().view;
         let sun_angle = frame.sky.sun_angle.to_radians();
         // Celestial bodies rotate around the X axis; angle 0 = noon.
         let sun = Vec3::new(0.0, sun_angle.cos(), -sun_angle.sin());
@@ -3761,8 +3800,8 @@ impl Renderer {
             misc: [
                 1.0 - frame.sky.sky_light_factor,
                 frame.game_time,
-                aspect,
-                (frame.fov_degrees.to_radians() / 2.0).tan(),
+                views.primary().aspect,
+                views.primary().tan_half_fov,
             ],
             inverse_view: view.inverse().to_cols_array_2d(),
             sunrise: frame.sky.sunrise_color,
@@ -3825,14 +3864,15 @@ impl Renderer {
             bytemuck::bytes_of(&crosshair_globals),
         );
         // Frustum culling and camera-relative origins.
+        let cull_proj = views.cull().view_proj(pose);
         let view = Frustum {
-            planes: frustum(view_proj),
+            planes: frustum(cull_proj),
         };
         let camera = frame.camera;
         let camera_section = camera_section(camera);
         // Solid quads facing away from the eye are left out: the bob moves
         // the eye off `camera`, so it is found from the projection.
-        let eye = projection_center(view_proj).filter(|_| self.sides_on);
+        let eye = projection_center(cull_proj).filter(|_| self.sides_on);
         let culling = !frame.title && frame.cave_culling;
         if culling {
             crate::spans::time("occlusion", || {
@@ -5294,7 +5334,11 @@ impl Renderer {
             // The copy and PNG writer both assume 8-bit pixels; a float surface would make
             // the row stride too small for the copy and abort in validation.
             if self.config.format.block_copy_size(None) == Some(4) {
-                Some((path, self.copy_frame(&mut encoder, &target_texture)))
+                let size = [self.config.width, self.config.height];
+                Some((
+                    path,
+                    copy_frame(&self.device, &mut encoder, &target_texture, size),
+                ))
             } else {
                 self.screenshot_result = Some(Err(format!(
                     "screenshots need a 32-bit surface format, not {:?}",
@@ -5308,6 +5352,10 @@ impl Renderer {
             self.section_copy_bytes = 0;
             self.section_uploads.finish(&encoder);
         }
+        if let Some(f) = &surface_frame {
+            self.readback
+                .present(&self.device, &mut encoder, &f.texture);
+        }
         if let (Some(hdr), Some(f)) = (&self.hdr, &surface_frame) {
             hdr.present(&self.queue, &mut encoder, &f.texture, !frame.title);
         }
@@ -5380,43 +5428,43 @@ impl Renderer {
         Ok(true)
     }
 }
+/// Bytes per row of a `width`-pixel frame read back at 4 bytes a pixel.
+fn padded_row(width: u32) -> u32 {
+    (width * 4).next_multiple_of(wgpu::COPY_BYTES_PER_ROW_ALIGNMENT)
+}
+/// Encodes the copy of `texture`'s `size` pixels into a mappable buffer.
+fn copy_frame(
+    device: &wgpu::Device,
+    encoder: &mut wgpu::CommandEncoder,
+    texture: &wgpu::Texture,
+    [width, height]: [u32; 2],
+) -> wgpu::Buffer {
+    let buffer = device.create_buffer(&wgpu::BufferDescriptor {
+        label: Some("Horizon screenshot"),
+        size: u64::from(padded_row(width)) * u64::from(height),
+        usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
+        mapped_at_creation: false,
+    });
+    encoder.copy_texture_to_buffer(
+        texture.as_image_copy(),
+        wgpu::TexelCopyBufferInfo {
+            buffer: &buffer,
+            layout: wgpu::TexelCopyBufferLayout {
+                offset: 0,
+                bytes_per_row: Some(padded_row(width)),
+                rows_per_image: None,
+            },
+        },
+        wgpu::Extent3d {
+            width,
+            height,
+            depth_or_array_layers: 1,
+        },
+    );
+    buffer
+}
 impl Renderer {
-    fn padded_row(&self) -> u32 {
-        (self.config.width * 4).next_multiple_of(wgpu::COPY_BYTES_PER_ROW_ALIGNMENT)
-    }
-    fn copy_frame(
-        &self,
-        encoder: &mut wgpu::CommandEncoder,
-        texture: &wgpu::Texture,
-    ) -> wgpu::Buffer {
-        let buffer = self.device.create_buffer(&wgpu::BufferDescriptor {
-            label: Some("Horizon screenshot"),
-            size: u64::from(self.padded_row()) * u64::from(self.config.height),
-            usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
-            mapped_at_creation: false,
-        });
-        encoder.copy_texture_to_buffer(
-            texture.as_image_copy(),
-            wgpu::TexelCopyBufferInfo {
-                buffer: &buffer,
-                layout: wgpu::TexelCopyBufferLayout {
-                    offset: 0,
-                    bytes_per_row: Some(self.padded_row()),
-                    rows_per_image: None,
-                },
-            },
-            wgpu::Extent3d {
-                width: self.config.width,
-                height: self.config.height,
-                depth_or_array_layers: 1,
-            },
-        );
-        buffer
-    }
     fn write_screenshot(&self, path: &std::path::Path, buffer: &wgpu::Buffer) -> Result<[u32; 2]> {
-        if !self.config.usage.contains(wgpu::TextureUsages::COPY_SRC) {
-            return Err("this surface does not support frame readback".into());
-        }
         let (sender, receiver) = std::sync::mpsc::channel();
         buffer.map_async(wgpu::MapMode::Read, .., move |r| {
             let _ = sender.send(r);
@@ -5431,7 +5479,7 @@ impl Renderer {
         let (width, height, row) = (
             self.config.width,
             self.config.height,
-            self.padded_row() as usize,
+            padded_row(self.config.width) as usize,
         );
         let bgra = matches!(
             self.config.format.remove_srgb_suffix(),
@@ -5553,6 +5601,23 @@ fn frustum(m: Mat4) -> [Vec4; 6] {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn drawable_size_skips_minimized_and_oversized_windows() {
+        use super::drawable_size;
+        assert!(drawable_size(1280, 720, 8192));
+        assert!(drawable_size(1, 1, 8192));
+        assert!(drawable_size(8192, 8192, 8192));
+        // Minimized.
+        assert!(!drawable_size(0, 720, 8192));
+        assert!(!drawable_size(1280, 0, 8192));
+        assert!(!drawable_size(0, 0, 8192));
+        // One past the device's largest texture.
+        assert!(!drawable_size(8193, 720, 8192));
+        assert!(!drawable_size(1280, 8193, 8192));
+        // The crash: a window `SetWindowPos` made 65535 pixels tall, on an RTX 5080 (32768).
+        assert!(!drawable_size(984, 65496, 32768));
+        assert!(!drawable_size(984, u32::MAX, 32768));
+    }
     #[test]
     fn surface_is_8_bit_and_not_srgb() {
         use super::surface_format;

crates/horizon-client-render/src/gfx/compositor.rs

@@ -0,0 +1,214 @@
+//! Splitscreen: several players' renderers draw offscreen on one device, and the
+//! compositor copies each frame into its place on a window's surface. A window holds views but
+//! never owns them, so a view can later move to another window (another monitor, detached).
+use super::Renderer;
+use crate::Result;
+use std::sync::Arc;
+use winit::window::Window;
+
+pub struct Compositor {
+    surface: wgpu::Surface<'static>,
+    device: wgpu::Device,
+    queue: wgpu::Queue,
+    config: wgpu::SurfaceConfiguration,
+    present_modes: Vec<wgpu::PresentMode>,
+    suspended: bool,
+}
+
+impl Renderer {
+    /// A compositor for `window` on this renderer's device, presenting on the surface it gave up.
+    pub fn compositor(&self, window: Arc<Window>) -> Result<Compositor> {
+        // The surface this renderer set aside for its successor (`release_surface`), else a new
+        // one: a window can't keep two.
+        let spare = self
+            .spare_surface
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner)
+            .take();
+        let surface = match spare {
+            Some(surface) => surface,
+            None => self.instance.create_surface(window.clone())?,
+        };
+        Compositor::new(
+            surface,
+            &self.adapter,
+            &self.device,
+            &self.queue,
+            window.inner_size().into(),
+        )
+    }
+
+    /// The last offscreen frame (`--offscreen`), for the compositor.
+    pub fn offscreen_frame(&self) -> Option<&wgpu::Texture> {
+        self.offscreen.as_ref()
+    }
+
+    /// Splitscreen turned off: a compositor's surface, set aside for the renderer that draws on
+    /// the window again (it takes it, as after `release_surface`).
+    pub fn take_back(&self, compositor: Compositor) {
+        *self
+            .spare_surface
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner) = Some(compositor.surface);
+    }
+}
+
+impl Compositor {
+    /// Present offscreen BGRA frames on a compatible surface using their existing device.
+    /// The surface must support COPY_DST and Bgra8Unorm; unsupported surfaces return an error.
+    pub fn new(
+        surface: wgpu::Surface<'static>,
+        adapter: &wgpu::Adapter,
+        device: &wgpu::Device,
+        queue: &wgpu::Queue,
+        size: [u32; 2],
+    ) -> Result<Self> {
+        let caps = surface.get_capabilities(adapter);
+        // ponytail: a plain texture copy needs the offscreen frames' format; a blit pass would
+        // take any surface format (Rgba8Unorm on some Linux drivers).
+        if !caps.usages.contains(wgpu::TextureUsages::COPY_DST) {
+            return Err("surface does not support copying offscreen frames".into());
+        }
+        let format = wgpu::TextureFormat::Bgra8Unorm;
+        if !caps.formats.contains(&format) {
+            return Err(format!(
+                "splitscreen needs a {format:?} surface; this one offers {:?}",
+                caps.formats
+            )
+            .into());
+        }
+        let max = device.limits().max_texture_dimension_2d;
+        let config = wgpu::SurfaceConfiguration {
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_DST,
+            format,
+            width: size[0].clamp(1, max),
+            height: size[1].clamp(1, max),
+            present_mode: wgpu::PresentMode::Fifo,
+            desired_maximum_frame_latency: 2,
+            alpha_mode: wgpu::CompositeAlphaMode::Opaque,
+            view_formats: vec![],
+            color_space: wgpu::SurfaceColorSpace::default(),
+        };
+        surface.configure(device, &config);
+        Ok(Compositor {
+            surface,
+            device: device.clone(),
+            queue: queue.clone(),
+            config,
+            present_modes: caps.present_modes,
+            suspended: !super::drawable_size(size[0], size[1], max),
+        })
+    }
+
+    /// Vsync on: presents wait for the display. Off: they don't (Mailbox, else Immediate).
+    pub fn set_vsync(&mut self, vsync: bool) {
+        let mode = [wgpu::PresentMode::Mailbox, wgpu::PresentMode::Immediate]
+            .into_iter()
+            .find(|m| !vsync && self.present_modes.contains(m))
+            .unwrap_or(wgpu::PresentMode::Fifo);
+        if mode != self.config.present_mode {
+            self.config.present_mode = mode;
+            self.surface.configure(&self.device, &self.config);
+        }
+    }
+
+    pub fn resize(&mut self, width: u32, height: u32) {
+        self.suspended =
+            !super::drawable_size(width, height, self.device.limits().max_texture_dimension_2d);
+        if !self.suspended {
+            self.config.width = width;
+            self.config.height = height;
+            self.surface.configure(&self.device, &self.config);
+        }
+    }
+
+    /// Copy each view's frame to its top-left corner on the window and present. Frames that
+    /// don't fit are clipped; parts of the window no view covers (a view before its first frame,
+    /// one still at its old size after a resize) are black. Nothing when the window has no frame
+    /// to give (occluded, resized, timed out). Returns true when a frame was submitted.
+    pub fn present(&mut self, views: &[(&wgpu::Texture, [u32; 2])]) -> bool {
+        if self.suspended {
+            return false;
+        }
+        let frame = match self.surface.get_current_texture() {
+            wgpu::CurrentSurfaceTexture::Success(f)
+            | wgpu::CurrentSurfaceTexture::Suboptimal(f) => f,
+            wgpu::CurrentSurfaceTexture::Outdated | wgpu::CurrentSurfaceTexture::Lost => {
+                self.surface.configure(&self.device, &self.config);
+                return false;
+            }
+            _ => return false,
+        };
+        let mut encoder = self
+            .device
+            .create_command_encoder(&wgpu::CommandEncoderDescriptor {
+                label: Some("Splitscreen compositor"),
+            });
+        let target = frame.texture.create_view(&Default::default());
+        drop(encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("Splitscreen compositor clear"),
+            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                view: &target,
+                depth_slice: None,
+                resolve_target: None,
+                ops: wgpu::Operations {
+                    load: wgpu::LoadOp::Clear(wgpu::Color::BLACK),
+                    store: wgpu::StoreOp::Store,
+                },
+            })],
+            ..Default::default()
+        }));
+        for &(texture, [x, y]) in views {
+            let [width, height] = clipped_size(
+                [texture.width(), texture.height()],
+                [x, y],
+                [self.config.width, self.config.height],
+            );
+            if width == 0 || height == 0 {
+                continue;
+            }
+            encoder.copy_texture_to_texture(
+                texture.as_image_copy(),
+                wgpu::TexelCopyTextureInfo {
+                    origin: wgpu::Origin3d { x, y, z: 0 },
+                    ..frame.texture.as_image_copy()
+                },
+                wgpu::Extent3d {
+                    width,
+                    height,
+                    depth_or_array_layers: 1,
+                },
+            );
+        }
+        self.queue.submit([encoder.finish()]);
+        self.queue.present(frame);
+        true
+    }
+}
+
+/// Copies never reach past the surface, including while a resized view still has its old frame.
+fn clipped_size(view: [u32; 2], at: [u32; 2], surface: [u32; 2]) -> [u32; 2] {
+    [
+        view[0].min(surface[0].saturating_sub(at[0])),
+        view[1].min(surface[1].saturating_sub(at[1])),
+    ]
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn frames_are_clipped_to_the_window_during_resize() {
+        assert_eq!(clipped_size([640, 480], [0, 0], [1280, 720]), [640, 480]);
+        assert_eq!(
+            clipped_size([640, 480], [1000, 600], [1280, 720]),
+            [280, 120]
+        );
+        assert_eq!(clipped_size([640, 480], [1280, 720], [1280, 720]), [0, 0]);
+        assert_eq!(
+            clipped_size([640, 480], [u32::MAX, 0], [1280, 720]),
+            [0, 480]
+        );
+    }
+}

crates/horizon-client-render/src/gfx/hdr.rs

@@ -73,6 +73,8 @@ pub struct Hdr {
     /// Paper white and peak brightness, in nits.
     pub paper_white: f32,
     pub peak: f32,
+    /// The display's black level, in nits: shadows are lifted onto it (`hdr.wgsl`).
+    pub black: f32,
 }
 
 impl Hdr {
@@ -154,6 +156,7 @@ impl Hdr {
             debug: std::env::var_os("HORIZON_HDR_DEBUG").is_some_and(|v| v == "1"),
             paper_white: 200.0,
             peak: 1000.0,
+            black: 0.0,
         }
     }
 
@@ -240,7 +243,7 @@ impl Hdr {
             f32::from(u8::from(world)),
             f32::from(u8::from(self.debug)),
             f32::from(u8::from(self.output == Output::Pq)),
-            0.0,
+            self.black.clamp(0.0, paper),
             0.0,
             0.0,
         ];

crates/horizon-client-render/src/gfx/lightning.rs

@@ -15,10 +15,19 @@ pub struct Bolt {
 #[derive(Default)]
 pub struct Input<'a> {
     pub bolts: &'a [Bolt],
-    /// Current atlas white texel; a changed rect invalidates retained vertices.
+    /// Current atlas white texel ([`white_uv`]); a changed rect invalidates
+    /// retained vertices.
     pub uv: [f32; 2],
 }
 
+/// The atlas point an untextured quad (`RenderTypes.lightning` has no
+/// texture) samples: the middle of the white sprite. Its corner (`u0`, `v0`)
+/// is on the sprite's border, where the atlas's nearest sampling picks the
+/// neighbouring, transparent texels for most fragments.
+pub fn white_uv(white: &crate::hud::Rect) -> [f32; 2] {
+    [(white.u0 + white.u1) / 2.0, (white.v0 + white.v1) / 2.0]
+}
+
 // Four layers, fourteen segments (eight trunk, two branches of three), four quads.
 pub(super) const QUADS: u32 = 4 * 14 * 4;
 

crates/horizon-client-render/src/gfx/lightning/tests/mod.rs

@@ -496,3 +496,253 @@ fn retained_gpu_draw_matches_transient_additive_draw() {
         assert_eq!(pixels[0], pixels[1], "frame {frame}: GPU output differs");
     }
 }
+
+/// `horizon/white` (4x4 texels) at (40, 12) of a 64x32 atlas.
+const ATLAS: (u32, u32) = (64, 32);
+fn white_sprite() -> crate::hud::Rect {
+    let (w, h) = (ATLAS.0 as f32, ATLAS.1 as f32);
+    crate::hud::Rect {
+        u0: 40.0 / w,
+        v0: 12.0 / h,
+        u1: 44.0 / w,
+        v1: 16.0 / h,
+        w: 4,
+        h: 4,
+    }
+}
+
+/// The white sprite's corner is on its border with the next atlas texels,
+/// which nearest sampling picks for most of a bolt's fragments (#3171): the
+/// point sampled is at least a texel inside the sprite.
+#[test]
+fn white_uv_is_inside_the_white_sprite() {
+    let [u, v] = white_uv(&white_sprite());
+    let (x, y) = (u * ATLAS.0 as f32, v * ATLAS.1 as f32);
+    assert!((41.0..=43.0).contains(&x), "u at texel {x}");
+    assert!((13.0..=15.0).contains(&y), "v at texel {y}");
+}
+
+/// A bolt seen from 14 blocks through the atlas as the game binds it (nearest
+/// sampling, only the white sprite opaque) draws the same pixels as through a
+/// texture that is white everywhere (#3171: the sprite's corner left a few
+/// scattered pixels). Run explicitly, like the test above.
+#[test]
+#[ignore = "requires GPU; run separately with --ignored --exact"]
+fn bolt_through_the_atlas_white_sprite_is_fully_drawn() {
+    let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_without_display_handle());
+    let Ok(adapter) = pollster::block_on(instance.request_adapter(&Default::default())) else {
+        eprintln!("no GPU adapter: skipped");
+        return;
+    };
+    let (device, queue) = pollster::block_on(adapter.request_device(&Default::default())).unwrap();
+    let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+        label: None,
+        source: wgpu::ShaderSource::Wgsl(crate::gfx::entity_shader().into()),
+    });
+    let attributes = wgpu::vertex_attr_array![0=>Float32x3,1=>Float32x2,2=>Uint32,3=>Unorm8x4,4=>Uint8x4,5=>Snorm8x4,6=>Float32x2];
+    let offsets = wgpu::vertex_attr_array![7=>Float32x3];
+    let buffers = [
+        Some(wgpu::VertexBufferLayout {
+            array_stride: std::mem::size_of::<Vertex>() as u64,
+            step_mode: wgpu::VertexStepMode::Vertex,
+            attributes: &attributes,
+        }),
+        Some(wgpu::VertexBufferLayout {
+            array_stride: 12,
+            step_mode: wgpu::VertexStepMode::Instance,
+            attributes: &offsets,
+        }),
+    ];
+    // The lightning pipeline (gfx.rs): additive, into RGBA8.
+    let additive = wgpu::BlendComponent {
+        src_factor: wgpu::BlendFactor::SrcAlpha,
+        dst_factor: wgpu::BlendFactor::One,
+        operation: wgpu::BlendOperation::Add,
+    };
+    let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+        label: None,
+        layout: None,
+        vertex: wgpu::VertexState {
+            module: &shader,
+            entry_point: Some("vs_lightning"),
+            compilation_options: Default::default(),
+            buffers: &buffers,
+        },
+        primitive: wgpu::PrimitiveState {
+            cull_mode: None,
+            ..Default::default()
+        },
+        depth_stencil: None,
+        multisample: Default::default(),
+        fragment: Some(wgpu::FragmentState {
+            module: &shader,
+            entry_point: Some("fs_celestial"),
+            compilation_options: Default::default(),
+            targets: &[Some(wgpu::ColorTargetState {
+                format: wgpu::TextureFormat::Rgba8Unorm,
+                blend: Some(wgpu::BlendState {
+                    color: additive,
+                    alpha: additive,
+                }),
+                write_mask: wgpu::ColorWrites::ALL,
+            })],
+        }),
+        multiview_mask: None,
+        cache: None,
+    });
+    // The game's camera: 70 degrees, reversed depth, the bolt 14 blocks ahead.
+    let globals = crate::gfx::Globals {
+        view_proj: (glam::Mat4::perspective_rh(70f32.to_radians(), 1.0, 400.0, 0.05)
+            * glam::Mat4::look_at_rh(glam::Vec3::ZERO, glam::Vec3::Z, glam::Vec3::Y))
+        .to_cols_array_2d(),
+        ..bytemuck::Zeroable::zeroed()
+    };
+    let globals = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+        label: None,
+        contents: bytemuck::bytes_of(&globals),
+        usage: wgpu::BufferUsages::UNIFORM,
+    });
+    let texture = |(width, height): (u32, u32), data: &[u8]| {
+        device
+            .create_texture_with_data(
+                &queue,
+                &wgpu::TextureDescriptor {
+                    label: None,
+                    size: wgpu::Extent3d {
+                        width,
+                        height,
+                        depth_or_array_layers: 1,
+                    },
+                    mip_level_count: 1,
+                    sample_count: 1,
+                    dimension: wgpu::TextureDimension::D2,
+                    format: wgpu::TextureFormat::Rgba8Unorm,
+                    usage: wgpu::TextureUsages::TEXTURE_BINDING,
+                    view_formats: &[],
+                },
+                wgpu::util::TextureDataOrder::LayerMajor,
+                data,
+            )
+            .create_view(&Default::default())
+    };
+    let white = texture((1, 1), &[255; 4]);
+    // Transparent but for the white sprite.
+    let mut texels = vec![0u8; (ATLAS.0 * ATLAS.1 * 4) as usize];
+    for y in 12..16 {
+        for x in 40..44 {
+            let i = ((y * ATLAS.0 + x) * 4) as usize;
+            texels[i..i + 4].copy_from_slice(&[255; 4]);
+        }
+    }
+    let atlas = texture(ATLAS, &texels);
+    // The atlas sampler (gfx.rs): wgpu's default, nearest.
+    let sampler = device.create_sampler(&Default::default());
+    let indices = crate::gfx::Renderer::quad_indices(&device, QUADS);
+    let size = 256;
+    let extent = wgpu::Extent3d {
+        width: size,
+        height: size,
+        depth_or_array_layers: 1,
+    };
+    let draw = |view: &wgpu::TextureView, uv: [f32; 2]| -> Vec<u8> {
+        let group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label: None,
+            layout: &pipeline.get_bind_group_layout(0),
+            entries: &[
+                wgpu::BindGroupEntry {
+                    binding: 0,
+                    resource: globals.as_entire_binding(),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 1,
+                    resource: wgpu::BindingResource::TextureView(view),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 2,
+                    resource: wgpu::BindingResource::Sampler(&sampler),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 3,
+                    resource: wgpu::BindingResource::TextureView(&white),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 4,
+                    resource: wgpu::BindingResource::Sampler(&sampler),
+                },
+            ],
+        });
+        let bolts = [Bolt {
+            seed: 123,
+            at: [0.0, -1.62, 14.0],
+        }];
+        let input = Input { bolts: &bolts, uv };
+        let mut renderer = Renderer::new();
+        let mut uploads = Uploads::new(&device);
+        let mut encoder = device.create_command_encoder(&Default::default());
+        renderer.prepare(&device, &mut uploads, &mut encoder, &input, DVec3::ZERO);
+        let color = device.create_texture(&wgpu::TextureDescriptor {
+            label: None,
+            size: extent,
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: wgpu::TextureFormat::Rgba8Unorm,
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
+            view_formats: &[],
+        });
+        {
+            let target = color.create_view(&Default::default());
+            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+                label: None,
+                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                    view: &target,
+                    resolve_target: None,
+                    depth_slice: None,
+                    ops: wgpu::Operations {
+                        load: wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
+                        store: wgpu::StoreOp::Store,
+                    },
+                })],
+                ..Default::default()
+            });
+            pass.set_pipeline(&pipeline);
+            pass.set_bind_group(0, &group, &[]);
+            pass.set_index_buffer(indices.slice(..), wgpu::IndexFormat::Uint32);
+            renderer.draw(&mut pass, &input);
+        }
+        let read = device.create_buffer(&wgpu::BufferDescriptor {
+            label: None,
+            size: u64::from(size * size * 4),
+            usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
+            mapped_at_creation: false,
+        });
+        encoder.copy_texture_to_buffer(
+            color.as_image_copy(),
+            wgpu::TexelCopyBufferInfo {
+                buffer: &read,
+                layout: wgpu::TexelCopyBufferLayout {
+                    offset: 0,
+                    bytes_per_row: Some(size * 4),
+                    rows_per_image: None,
+                },
+            },
+            extent,
+        );
+        uploads.finish(&encoder);
+        queue.submit([encoder.finish()]);
+        read.slice(..)
+            .map_async(wgpu::MapMode::Read, |r| r.unwrap());
+        device.poll(wgpu::PollType::wait_indefinitely()).unwrap();
+        read.slice(..).get_mapped_range().unwrap().to_vec()
+    };
+    let lit = |pixels: &[u8]| pixels.chunks(4).filter(|p| p[3] != 0).count();
+    let expected = draw(&white, [0.5; 2]);
+    let drawn = draw(&atlas, white_uv(&white_sprite()));
+    assert!(lit(&expected) > 1000, "{} pixels", lit(&expected));
+    assert_eq!(
+        lit(&drawn),
+        lit(&expected),
+        "pixels drawn through the atlas"
+    );
+    assert!(drawn == expected, "the bolt's colours through the atlas");
+}

crates/horizon-client-render/src/gfx/pack_post.rs

@@ -476,10 +476,12 @@ fn sampler(
     })
 }
 
-/// Runs `create` and returns its validation error, if any.
+/// Runs `create` and returns its validation error, if any. A panic while it runs is an error
+/// too: naga's backends turn a module they cannot write into a panic as the driver gets the
+/// pipeline (#3525), which a pack's program must not turn into a crash.
 fn checked<T>(device: &wgpu::Device, create: impl FnOnce() -> T) -> Result<T, String> {
     let scope = device.push_error_scope(wgpu::ErrorFilter::Validation);
-    let value = create();
+    let value = crate::crash::contain(create);
     match pollster::block_on(scope.pop()) {
         Some(e) => {
             // The details are in the error's description or its sources.
@@ -494,7 +496,7 @@ fn checked<T>(device: &wgpu::Device, create: impl FnOnce() -> T) -> Result<T, St
             }
             Err(message)
         }
-        None => Ok(value),
+        None => value.map_err(|panic| format!("the shader compiler failed: {panic}")),
     }
 }
 
@@ -2629,6 +2631,38 @@ mod tests {
         assert_eq!(used, [1, 2, 3]);
     }
 
+    /// #3525: naga's SPIR-V writer panicked on Photon's gbuffers programs as the pipeline was
+    /// made. Such a panic skips the pass, as a validation error does, and the device goes on.
+    #[test]
+    fn a_shader_compiler_panic_skips_the_pass() {
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_without_display_handle());
+        let Ok(adapter) = pollster::block_on(instance.request_adapter(&Default::default())) else {
+            return;
+        };
+        let Ok((device, _queue)) = pollster::block_on(adapter.request_device(&Default::default()))
+        else {
+            return;
+        };
+        let failed = checked(&device, || -> wgpu::Buffer {
+            panic!("internal error: entered unreachable code: Expression [89] is not cached!")
+        });
+        let error = failed.expect_err("the panic comes back as an error");
+        assert!(error.contains("Expression [89] is not cached!"), "{error}");
+        let buffer = |usage| {
+            checked(&device, || {
+                device.create_buffer(&wgpu::BufferDescriptor {
+                    label: None,
+                    size: 16,
+                    usage,
+                    mapped_at_creation: false,
+                })
+            })
+        };
+        // The device still makes things, and its errors still come back.
+        assert!(buffer(wgpu::BufferUsages::UNIFORM).is_ok());
+        assert!(buffer(wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::MAP_WRITE).is_err());
+    }
+
     #[test]
     fn pack_formats_map_to_renderable_ones() {
         let f = |name| texture_format(Format::parse(name).unwrap(), wgpu::Features::empty());

crates/horizon-client-render/src/gfx/readback.rs

@@ -0,0 +1,213 @@
+//! Screenshots of a swapchain that cannot be copied from. OpenGL's surfaces
+//! offer `RENDER_ATTACHMENT` only, so a frame whose pixels are read back
+//! (the screenshot key, a world's icon) is drawn into a texture that can be,
+//! then drawn onto the swapchain image as a fullscreen triangle.
+
+/// The texture a frame to read back is drawn into, and the pass that puts it
+/// on the swapchain afterwards.
+#[derive(Default)]
+pub struct Readback {
+    texture: Option<wgpu::Texture>,
+    blitter: Option<(wgpu::TextureFormat, wgpu::util::TextureBlitter)>,
+    /// A frame drew into `texture` and still has to reach the swapchain.
+    drawn: bool,
+}
+
+impl Readback {
+    /// The texture this frame draws into instead of the swapchain image
+    /// `surface`: `None` unless the frame is read back (`screenshot`) and the
+    /// image cannot be copied from.
+    pub fn target(
+        &mut self,
+        device: &wgpu::Device,
+        surface: &wgpu::Texture,
+        screenshot: bool,
+    ) -> Option<wgpu::Texture> {
+        if !screenshot || surface.usage().contains(wgpu::TextureUsages::COPY_SRC) {
+            return None;
+        }
+        let format = surface.format().remove_srgb_suffix();
+        if self
+            .texture
+            .as_ref()
+            .is_none_or(|t| t.size() != surface.size() || t.format() != format)
+        {
+            self.texture = Some(device.create_texture(&wgpu::TextureDescriptor {
+                label: Some("Horizon screenshot frame"),
+                size: surface.size(),
+                mip_level_count: 1,
+                sample_count: 1,
+                dimension: wgpu::TextureDimension::D2,
+                format,
+                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
+                    | wgpu::TextureUsages::COPY_SRC
+                    | wgpu::TextureUsages::TEXTURE_BINDING,
+                view_formats: &[],
+            }));
+        }
+        self.drawn = true;
+        self.texture.clone()
+    }
+
+    /// Draws the frame `target` gave onto the swapchain image `surface`; nothing
+    /// when this frame drew straight into it.
+    pub fn present(
+        &mut self,
+        device: &wgpu::Device,
+        encoder: &mut wgpu::CommandEncoder,
+        surface: &wgpu::Texture,
+    ) {
+        if !std::mem::take(&mut self.drawn) {
+            return;
+        }
+        let Some(texture) = &self.texture else {
+            return;
+        };
+        // The frame's passes write the swapchain through its non-sRGB view
+        // (`view_formats`), so the copy goes there unconverted too.
+        let format = surface.format().remove_srgb_suffix();
+        if self.blitter.as_ref().is_none_or(|b| b.0 != format) {
+            self.blitter = Some((format, wgpu::util::TextureBlitter::new(device, format)));
+        }
+        let target = surface.create_view(&wgpu::TextureViewDescriptor {
+            format: Some(format),
+            ..Default::default()
+        });
+        let source = texture.create_view(&Default::default());
+        if let Some((_, blitter)) = &self.blitter {
+            blitter.copy(device, encoder, &source, &target);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn device() -> Option<(wgpu::Device, wgpu::Queue)> {
+        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor::new_without_display_handle());
+        let adapter = pollster::block_on(instance.request_adapter(&Default::default())).ok()?;
+        pollster::block_on(adapter.request_device(&Default::default())).ok()
+    }
+
+    fn texture(device: &wgpu::Device, usage: wgpu::TextureUsages) -> wgpu::Texture {
+        device.create_texture(&wgpu::TextureDescriptor {
+            label: None,
+            size: wgpu::Extent3d {
+                width: 70,
+                height: 3,
+                depth_or_array_layers: 1,
+            },
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: wgpu::TextureFormat::Bgra8Unorm,
+            usage,
+            view_formats: &[],
+        })
+    }
+
+    fn clear(encoder: &mut wgpu::CommandEncoder, texture: &wgpu::Texture, color: wgpu::Color) {
+        let view = texture.create_view(&Default::default());
+        encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: None,
+            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                view: &view,
+                resolve_target: None,
+                depth_slice: None,
+                ops: wgpu::Operations {
+                    load: wgpu::LoadOp::Clear(color),
+                    store: wgpu::StoreOp::Store,
+                },
+            })],
+            ..Default::default()
+        });
+    }
+
+    fn read(device: &wgpu::Device, buffer: &wgpu::Buffer) -> Vec<u8> {
+        buffer.map_async(wgpu::MapMode::Read, .., |r| r.unwrap());
+        device.poll(wgpu::PollType::wait_indefinitely()).unwrap();
+        buffer.get_mapped_range(..).unwrap().to_vec()
+    }
+
+    /// The last pixel of the last row of a 70x3 frame read back by `copy_frame`.
+    fn last_pixel(device: &wgpu::Device, buffer: &wgpu::Buffer) -> Vec<u8> {
+        let pixels = read(device, buffer);
+        let row = 70usize * 4;
+        let last = row.next_multiple_of(256) * 2 + row - 4;
+        pixels[last..last + 4].to_vec()
+    }
+
+    /// The renderer's screenshot path on a surface like OpenGL's (#3510): the
+    /// frame is drawn into `target`, read back with `copy_frame` and drawn on
+    /// the swapchain, with no validation error (the copy used to need the
+    /// swapchain's missing `COPY_SRC`), and the swapchain shows the frame.
+    #[test]
+    fn screenshot_of_a_surface_without_copy_src() {
+        let Some((device, queue)) = device() else {
+            return;
+        };
+        // Sampled only so the test can look at what reached it.
+        let surface = texture(
+            &device,
+            wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
+        );
+        let check = texture(
+            &device,
+            wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
+        );
+        let blitter = wgpu::util::TextureBlitter::new(&device, wgpu::TextureFormat::Bgra8Unorm);
+        let mut readback = Readback::default();
+        let colors = [
+            (1.0, [0, 0, 255, 255]),
+            // A second screenshot reuses the texture.
+            (0.0, [255, 0, 0, 255]),
+        ];
+        for (r, bgra) in colors {
+            let color = wgpu::Color {
+                r,
+                g: 0.0,
+                b: 1.0 - r,
+                a: 1.0,
+            };
+            let scope = device.push_error_scope(wgpu::ErrorFilter::Validation);
+            let mut encoder = device.create_command_encoder(&Default::default());
+            let frame = readback
+                .target(&device, &surface, true)
+                .unwrap_or_else(|| surface.clone());
+            clear(&mut encoder, &frame, color);
+            let buffer = crate::gfx::copy_frame(&device, &mut encoder, &frame, [70, 3]);
+            readback.present(&device, &mut encoder, &surface);
+            queue.submit([encoder.finish()]);
+            if let Some(error) = pollster::block_on(scope.pop()) {
+                panic!("{error}");
+            }
+            assert_eq!(last_pixel(&device, &buffer), bgra);
+            let mut encoder = device.create_command_encoder(&Default::default());
+            let view = |t: &wgpu::Texture| t.create_view(&Default::default());
+            blitter.copy(&device, &mut encoder, &view(&surface), &view(&check));
+            let buffer = crate::gfx::copy_frame(&device, &mut encoder, &check, [70, 3]);
+            queue.submit([encoder.finish()]);
+            assert_eq!(last_pixel(&device, &buffer), bgra);
+        }
+        assert!(!readback.drawn);
+    }
+
+    /// A surface that can be copied from, or a frame nobody reads back,
+    /// draws straight into the swapchain image.
+    #[test]
+    fn frames_draw_straight_to_a_readable_surface() {
+        let Some((device, _)) = device() else {
+            return;
+        };
+        let mut readback = Readback::default();
+        let readable = texture(
+            &device,
+            wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
+        );
+        assert!(readback.target(&device, &readable, true).is_none());
+        let surface = texture(&device, wgpu::TextureUsages::RENDER_ATTACHMENT);
+        assert!(readback.target(&device, &surface, false).is_none());
+        assert!(readback.texture.is_none() && !readback.drawn);
+    }
+}

crates/horizon-client-render/src/gfx/view.rs

@@ -0,0 +1,133 @@
+//! The views a frame is drawn from. A flat screen has one; a headset has
+//! one per eye. Every view shares the frame's camera position, so the
+//! camera-relative world (section origins, entity offsets) is built once and
+//! only each view's rotation and lens differ.
+
+use glam::Mat4;
+
+/// The most views one frame draws.
+const MAX_VIEWS: usize = 2;
+
+/// One eye's view of the camera-relative world.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct View {
+    /// Camera-relative world to eye: a rotation, plus the eye's offset from
+    /// the camera on a headset.
+    pub view: Mat4,
+    /// Reversed-Z perspective: the near plane at depth 1, far at 0.
+    pub projection: Mat4,
+    /// Width over height of the image this view fills.
+    pub aspect: f32,
+    /// `tan(fov_y / 2)`, for shaders rebuilding view rays from NDC.
+    pub tan_half_fov: f32,
+}
+
+impl View {
+    /// The flat-screen view: vanilla's camera rotation and a symmetric
+    /// vertical field of view.
+    pub fn screen(yaw: f32, pitch: f32, fov_degrees: f32, aspect: f32, far: f32) -> Self {
+        Self {
+            view: crate::camera::view_matrix(yaw, pitch),
+            projection: super::world_projection(fov_degrees, aspect, far),
+            aspect,
+            tan_half_fov: (fov_degrees.to_radians() / 2.0).tan(),
+        }
+    }
+
+    /// Clip space from the camera-relative world, with `pose` (view bobbing,
+    /// nausea spin) between the lens and the rotation.
+    pub fn view_proj(&self, pose: Mat4) -> Mat4 {
+        self.projection * pose * self.view
+    }
+}
+
+/// Every view of a frame, and the one geometry is culled with.
+#[derive(Clone, Copy, Debug)]
+pub struct ViewSet {
+    views: [View; MAX_VIEWS],
+    len: usize,
+    cull: View,
+}
+
+impl ViewSet {
+    /// A frame drawn from `view` alone, culled with it.
+    pub fn single(view: View) -> Self {
+        Self {
+            views: [view; MAX_VIEWS],
+            len: 1,
+            cull: view,
+        }
+    }
+
+    /// The view the HUD, hand and screen-space effects follow.
+    pub fn primary(&self) -> &View {
+        &self.views[0]
+    }
+
+    pub fn views(&self) -> &[View] {
+        &self.views[..self.len]
+    }
+
+    /// The view whose frustum covers every other view's.
+    pub fn cull(&self) -> &View {
+        &self.cull
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// The formulas `Renderer` used before views existed, kept to pin the
+    /// screen view to them bit for bit.
+    fn legacy_view_proj(fov: f32, yaw: f32, pitch: f32, pose: Mat4, aspect: f32, far: f32) -> Mat4 {
+        super::super::world_projection(fov, aspect, far)
+            * pose
+            * crate::camera::view_matrix(yaw, pitch)
+    }
+
+    fn poses() -> [Mat4; 3] {
+        [
+            Mat4::IDENTITY,
+            Mat4::from_translation(glam::Vec3::new(0.013, -0.027, 0.0))
+                * Mat4::from_rotation_z(0.021),
+            Mat4::from_rotation_y(0.4) * Mat4::from_scale(glam::Vec3::new(1.1, 0.9, 1.0)),
+        ]
+    }
+
+    #[test]
+    fn the_screen_view_matches_the_legacy_projection_bit_for_bit() {
+        for (fov, yaw, pitch, aspect, far) in [
+            (70.0, 0.0, 0.0, 16.0 / 9.0, 512.0),
+            (110.0, -137.25, 61.5, 21.0 / 9.0, 8192.0),
+            (30.0, 359.9, -90.0, 4.0 / 3.0, 96.0),
+            (82.333, 12.5, 7.75, 1.0, 1024.0),
+        ] {
+            let view = View::screen(yaw, pitch, fov, aspect, far);
+            for pose in poses() {
+                let old = legacy_view_proj(fov, yaw, pitch, pose, aspect, far);
+                let new = view.view_proj(pose);
+                assert_eq!(
+                    old.to_cols_array().map(f32::to_bits),
+                    new.to_cols_array().map(f32::to_bits),
+                    "fov {fov} yaw {yaw} pitch {pitch}"
+                );
+            }
+            assert_eq!(view.view, crate::camera::view_matrix(yaw, pitch));
+            assert_eq!(
+                view.tan_half_fov.to_bits(),
+                (fov.to_radians() / 2.0).tan().to_bits()
+            );
+            assert_eq!(view.aspect.to_bits(), aspect.to_bits());
+        }
+    }
+
+    #[test]
+    fn a_single_view_set_draws_and_culls_with_its_view() {
+        let view = View::screen(45.0, 10.0, 70.0, 16.0 / 9.0, 512.0);
+        let set = ViewSet::single(view);
+        assert_eq!(set.views(), &[view]);
+        assert_eq!(*set.primary(), view);
+        assert_eq!(*set.cull(), view);
+    }
+}

crates/horizon-client-render/src/gfx/world_post.rs

@@ -41,6 +41,15 @@ struct TaaUniform {
     jitter: [f32; 4],
 }
 
+/// TAA's GPU resources, absent when the device cannot compile the shader
+/// (the OpenGL backend's naga GLSL emitter does not support `textureLoad`
+/// from depth textures).
+struct TaaResources {
+    layout: wgpu::BindGroupLayout,
+    pipeline: wgpu::RenderPipeline,
+    uniform: wgpu::Buffer,
+}
+
 pub struct Post {
     layout: wgpu::BindGroupLayout,
     sampler: wgpu::Sampler,
@@ -57,9 +66,7 @@ pub struct Post {
     /// TAA runs this frame (`jitter`): not on the title screen or under a shader pack.
     taa_on: bool,
     target: Option<WorldTarget>,
-    taa_layout: wgpu::BindGroupLayout,
-    taa_pipeline: wgpu::RenderPipeline,
-    taa_uniform: wgpu::Buffer,
+    taa_resources: Option<TaaResources>,
     /// Frames jittered so far (the Halton index), and which history the next resolve writes.
     taa_frame: u32,
     /// The last TAA frame's unjittered `view_proj` and camera, `None` once a frame ran without it.
@@ -105,40 +112,11 @@ impl Post {
             count: None,
         };
         let float = wgpu::TextureSampleType::Float { filterable: true };
-        let taa_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
-            label: Some("Horizon TAA bindings"),
-            entries: &[
-                texture(0, float),
-                wgpu::BindGroupLayoutEntry {
-                    binding: 1,
-                    visibility: wgpu::ShaderStages::FRAGMENT,
-                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
-                    count: None,
-                },
-                texture(2, float),
-                texture(3, wgpu::TextureSampleType::Depth),
-                wgpu::BindGroupLayoutEntry {
-                    binding: 4,
-                    visibility: wgpu::ShaderStages::FRAGMENT,
-                    ty: wgpu::BindingType::Buffer {
-                        ty: wgpu::BufferBindingType::Uniform,
-                        has_dynamic_offset: false,
-                        min_binding_size: None,
-                    },
-                    count: None,
-                },
-            ],
-        });
         let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
             label: Some("Horizon post"),
             bind_group_layouts: &[Some(&layout)],
             ..Default::default()
         });
-        let taa_pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
-            label: Some("Horizon TAA"),
-            bind_group_layouts: &[Some(&taa_layout)],
-            ..Default::default()
-        });
         let pipeline = |entry: &str, layout: &wgpu::PipelineLayout, format| {
             device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
                 label: Some("Horizon post"),
@@ -166,6 +144,88 @@ impl Post {
                 cache: None,
             })
         };
+        // The OpenGL backend's GLSL translator does not support textureLoad
+        // from depth textures: on devices running through OpenGL (such as older
+        // Intel GPUs on Linux), TAA cannot compile its pipeline.
+        let taa_resources = {
+            let taa_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+                label: Some("Horizon TAA bindings"),
+                entries: &[
+                    texture(0, float),
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 1,
+                        visibility: wgpu::ShaderStages::FRAGMENT,
+                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+                        count: None,
+                    },
+                    texture(2, float),
+                    texture(3, wgpu::TextureSampleType::Depth),
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 4,
+                        visibility: wgpu::ShaderStages::FRAGMENT,
+                        ty: wgpu::BindingType::Buffer {
+                            ty: wgpu::BufferBindingType::Uniform,
+                            has_dynamic_offset: false,
+                            min_binding_size: None,
+                        },
+                        count: None,
+                    },
+                ],
+            });
+            let taa_pipeline_layout =
+                device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+                    label: Some("Horizon TAA"),
+                    bind_group_layouts: &[Some(&taa_layout)],
+                    ..Default::default()
+                });
+            let validation = device.push_error_scope(wgpu::ErrorFilter::Validation);
+            let internal = device.push_error_scope(wgpu::ErrorFilter::Internal);
+            let taa_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+                label: Some("Horizon TAA"),
+                layout: Some(&taa_pipeline_layout),
+                vertex: wgpu::VertexState {
+                    module: &shader,
+                    entry_point: Some("vs_post"),
+                    compilation_options: Default::default(),
+                    buffers: &[],
+                },
+                primitive: Default::default(),
+                depth_stencil: None,
+                multisample: Default::default(),
+                fragment: Some(wgpu::FragmentState {
+                    module: &shader,
+                    entry_point: Some("fs_taa"),
+                    compilation_options: Default::default(),
+                    targets: &[Some(wgpu::ColorTargetState {
+                        format: HISTORY_FORMAT,
+                        blend: None,
+                        write_mask: wgpu::ColorWrites::ALL,
+                    })],
+                }),
+                multiview_mask: None,
+                cache: None,
+            });
+            let internal = pollster::block_on(internal.pop());
+            match internal.or(pollster::block_on(validation.pop())) {
+                None => {
+                    let uniform = device.create_buffer(&wgpu::BufferDescriptor {
+                        label: Some("Horizon TAA"),
+                        size: std::mem::size_of::<TaaUniform>() as u64,
+                        usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+                        mapped_at_creation: false,
+                    });
+                    Some(TaaResources {
+                        layout: taa_layout,
+                        pipeline: taa_pipeline,
+                        uniform,
+                    })
+                }
+                Some(e) => {
+                    log::warn!("Horizon renderer: temporal anti-aliasing unavailable ({e})");
+                    None
+                }
+            }
+        };
         let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
             label: Some("Horizon post"),
             mag_filter: wgpu::FilterMode::Linear,
@@ -175,15 +235,7 @@ impl Post {
         Self {
             copy: pipeline("fs_copy", &pipeline_layout, format),
             fxaa: pipeline("fs_fxaa", &pipeline_layout, format),
-            taa_pipeline: pipeline("fs_taa", &taa_pipeline_layout, HISTORY_FORMAT),
-            taa_uniform: device.create_buffer(&wgpu::BufferDescriptor {
-                label: Some("Horizon TAA"),
-                size: std::mem::size_of::<TaaUniform>() as u64,
-                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
-                mapped_at_creation: false,
-            }),
             layout,
-            taa_layout,
             sampler,
             format,
             scale: 1.0,
@@ -192,12 +244,18 @@ impl Post {
             upscale: 1.0,
             taa_on: false,
             target: None,
+            taa_resources,
             taa_frame: 0,
             taa_previous: None,
             taa_this_frame: bytemuck::Zeroable::zeroed(),
         }
     }
 
+    /// Whether TAA is supported on this GPU/backend.
+    pub fn supports_taa(&self) -> bool {
+        self.taa_resources.is_some()
+    }
+
     /// The world's rendered size and the size it is shown at (TAA's history).
     fn sizes(&self, window: [u32; 2]) -> ([u32; 2], [u32; 2]) {
         let output = window.map(|v| ((v as f32 * self.scale).round() as u32).clamp(1, 8192));
@@ -212,7 +270,7 @@ impl Post {
     /// world's projection (identity while `on` is false); `view_proj` is the unjittered
     /// projection, relative to `camera`. Call it before `prepare`, once per frame.
     pub fn jitter(&mut self, window: [u32; 2], on: bool, view_proj: Mat4, camera: DVec3) -> Mat4 {
-        self.taa_on = on && self.taa;
+        self.taa_on = on && self.taa && self.taa_resources.is_some();
         if !self.taa_on {
             self.taa_previous = None;
             return Mat4::IDENTITY;
@@ -290,7 +348,8 @@ impl Post {
             )
             .create_view(&Default::default());
             let group = self.bind(device, &color);
-            let taa = history_size.map(|output| {
+            let taa = history_size.and_then(|output| {
+                let res = self.taa_resources.as_ref()?;
                 let history = [0, 1].map(|_| {
                     make_tex("TAA history", output, HISTORY_FORMAT, sampled)
                         .create_view(&Default::default())
@@ -298,7 +357,7 @@ impl Post {
                 let resolve = [0, 1].map(|i| {
                     device.create_bind_group(&wgpu::BindGroupDescriptor {
                         label: Some("Horizon TAA"),
-                        layout: &self.taa_layout,
+                        layout: &res.layout,
                         entries: &[
                             wgpu::BindGroupEntry {
                                 binding: 0,
@@ -318,18 +377,18 @@ impl Post {
                             },
                             wgpu::BindGroupEntry {
                                 binding: 4,
-                                resource: self.taa_uniform.as_entire_binding(),
+                                resource: res.uniform.as_entire_binding(),
                             },
                         ],
                     })
                 });
                 let show = [0, 1].map(|i| self.bind(device, &history[i]));
-                History {
+                Some(History {
                     size: output,
                     history,
                     resolve,
                     show,
-                }
+                })
             });
             // New textures: no history yet.
             self.taa_this_frame.jitter[2] = 1.0;
@@ -381,12 +440,12 @@ impl Post {
             self.finish_with(encoder, screen, &target.group);
             return;
         };
+        let Some(res) = &self.taa_resources else {
+            self.finish_with(encoder, screen, &target.group);
+            return;
+        };
         let i = (self.taa_frame % 2) as usize;
-        queue.write_buffer(
-            &self.taa_uniform,
-            0,
-            bytemuck::bytes_of(&self.taa_this_frame),
-        );
+        queue.write_buffer(&res.uniform, 0, bytemuck::bytes_of(&self.taa_this_frame));
         let attachments = [Some(wgpu::RenderPassColorAttachment {
             view: &taa.history[i],
             resolve_target: None,
@@ -401,7 +460,7 @@ impl Post {
             color_attachments: &attachments,
             ..Default::default()
         });
-        pass.set_pipeline(&self.taa_pipeline);
+        pass.set_pipeline(&res.pipeline);
         pass.set_bind_group(0, &taa.resolve[i], &[]);
         pass.draw(0..3, 0..1);
         drop(pass);
@@ -485,4 +544,21 @@ mod tests {
             [0.5, 0.25, 0.75]
         );
     }
+
+    fn test_device() -> Option<(wgpu::Device, wgpu::Queue)> {
+        let instance =
+            wgpu::Instance::new(wgpu::InstanceDescriptor::new_without_display_handle().with_env());
+        let adapter = pollster::block_on(instance.request_adapter(&Default::default())).ok()?;
+        pollster::block_on(adapter.request_device(&Default::default())).ok()
+    }
+
+    #[test]
+    fn world_post_pipelines_compile_or_fall_back() {
+        let Some((device, _)) = test_device() else {
+            return;
+        };
+        let post = Post::new(&device, wgpu::TextureFormat::Rgba8Unorm);
+        // Copy and FXAA pipelines always compile; TAA compiles if supported by backend.
+        let _ = post.supports_taa();
+    }
 }

crates/horizon-client-render/src/graphics.rs

@@ -347,6 +347,9 @@ pub struct Graphics {
     pub hdr_paper_white: u32,
     /// HDR peak brightness the world's highlights reach, in nits.
     pub hdr_peak: u32,
+    /// HDR black level: the display's darkest black, in hundredths of a nit (0 for
+    /// an OLED's true black). Shadows are lifted onto it, and the HDR metadata says it.
+    pub hdr_black_level: u32,
     /// Battery mode: at most 60 frames per second in a world and 30 in menus
     /// or behind other windows, and half the worker threads. Off by default;
     /// it changes when frames are drawn, never what they show or the ticks.
@@ -383,6 +386,7 @@ impl Default for Graphics {
             hdr: false,
             hdr_paper_white: 200,
             hdr_peak: 1000,
+            hdr_black_level: 0,
             battery: false,
             api: GraphicsApi::Auto,
             shader_pack: String::new(),
@@ -447,6 +451,7 @@ impl Graphics {
                 "hdr" => g.hdr = flag(g.hdr),
                 "hdrPaperWhite" => g.hdr_paper_white = number(g.hdr_paper_white).clamp(80, 480),
                 "hdrPeak" => g.hdr_peak = number(g.hdr_peak).clamp(200, 2000),
+                "hdrBlackLevel" => g.hdr_black_level = number(g.hdr_black_level).min(100),
                 "batteryMode" => g.battery = flag(g.battery),
                 "graphicsApi" => g.api = GraphicsApi::from_name(value).unwrap_or_default(),
                 "pickedShaderPack" => g.shader_pack = value.to_owned(),
@@ -464,7 +469,7 @@ impl Graphics {
     }
     pub fn serialize(&self) -> String {
         format!(
-            "preset:{}\nlodDistance:{}\nfarDetail:{}\ncaveCulling:{}\nentityCulling:{}\nchunkUpdates:{}\nuploadBudgetKiB:{}\nsky:{}\nfog:{}\nweather:{}\nanimatedTextures:{}\npresentMode:{}\nframePacing:{}\nworkers:{}\noverlay:{}\nresolutionScale:{}\nfxaa:{}\ntaa:{}\nupscaling:{}\nhdr:{}\nhdrPaperWhite:{}\nhdrPeak:{}\nbatteryMode:{}\ngraphicsApi:{}\npickedShaderPack:{}\n",
+            "preset:{}\nlodDistance:{}\nfarDetail:{}\ncaveCulling:{}\nentityCulling:{}\nchunkUpdates:{}\nuploadBudgetKiB:{}\nsky:{}\nfog:{}\nweather:{}\nanimatedTextures:{}\npresentMode:{}\nframePacing:{}\nworkers:{}\noverlay:{}\nresolutionScale:{}\nfxaa:{}\ntaa:{}\nupscaling:{}\nhdr:{}\nhdrPaperWhite:{}\nhdrPeak:{}\nhdrBlackLevel:{}\nbatteryMode:{}\ngraphicsApi:{}\npickedShaderPack:{}\n",
             self.preset.name(),
             self.lod_distance,
             self.far_detail.name(),
@@ -494,6 +499,7 @@ impl Graphics {
             bool_text(self.hdr),
             self.hdr_paper_white,
             self.hdr_peak,
+            self.hdr_black_level,
             bool_text(self.battery),
             self.api.name(),
             self.shader_pack,
@@ -611,6 +617,7 @@ mod tests {
             hdr: true,
             hdr_paper_white: 240,
             hdr_peak: 1400,
+            hdr_black_level: 12,
             battery: true,
             api: GraphicsApi::Dx12,
             shader_pack: "Golden Hour".into(),

crates/horizon-client-render/src/graphics_ui.rs

@@ -38,8 +38,9 @@ pub enum H {
     Antialiasing,
     Upscaling,
     Hdr,
-    HdrPaperWhite,
+    HdrBlackLevel,
     HdrPeak,
+    HdrPaperWhite,
     BatteryMode,
     GraphicsApi,
 }
@@ -235,15 +236,20 @@ pub fn rows(level: Level) -> Vec<Row> {
                 "HDR output on an HDR display: lava, fire and sunlight shine brighter.",
             ),
             h(
-                H::HdrPaperWhite,
+                H::HdrBlackLevel,
                 None,
-                "HDR: how bright white paper and menus look. Match your desktop.",
+                "HDR: your display's darkest black. 0 for OLED; LCDs glow a little.",
             ),
             h(
                 H::HdrPeak,
                 None,
                 "HDR: how bright the brightest highlights get. Your display's peak.",
             ),
+            h(
+                H::HdrPaperWhite,
+                None,
+                "HDR: how bright white paper and menus look. Match your desktop.",
+            ),
             h(
                 H::PresentMode,
                 None,
@@ -353,6 +359,7 @@ impl H {
             H::ResolutionScale => Some((g.resolution_scale as f32 - 50.0) / 150.0),
             H::HdrPaperWhite => Some((g.hdr_paper_white as f32 - 80.0) / 400.0),
             H::HdrPeak => Some((g.hdr_peak as f32 - 200.0) / 1800.0),
+            H::HdrBlackLevel => Some(g.hdr_black_level as f32 / 100.0),
             _ => None,
         }
     }
@@ -405,6 +412,10 @@ impl H {
             H::Hdr => labelled("HDR", on_off(g.hdr)),
             H::HdrPaperWhite => labelled("Paper White", format!("{} nits", g.hdr_paper_white)),
             H::HdrPeak => labelled("Peak Brightness", format!("{} nits", g.hdr_peak)),
+            H::HdrBlackLevel => labelled(
+                "Black Level",
+                format!("{:.2} nits", g.hdr_black_level as f32 / 100.0),
+            ),
             H::BatteryMode => labelled("Battery Mode", on_off(g.battery)),
             H::GraphicsApi => labelled("Graphics API", g.api.label()),
             H::Overlay => labelled(
@@ -429,6 +440,7 @@ impl H {
             H::ResolutionScale => g.resolution_scale = (50.0 + (v * 30.0).round() * 5.0) as u32,
             H::HdrPaperWhite => g.hdr_paper_white = (80.0 + (v * 40.0).round() * 10.0) as u32,
             H::HdrPeak => g.hdr_peak = (200.0 + (v * 36.0).round() * 50.0) as u32,
+            H::HdrBlackLevel => g.hdr_black_level = (v * 100.0).round() as u32,
             _ => {}
         }
     }
@@ -624,15 +636,20 @@ struct Widget {
 
 #[derive(Default)]
 pub struct GraphicsUi {
-    scroll: f32,
+    /// The list's scroll amount and its held scrollbar (`AbstractScrollArea`).
+    scroll: ui::Scroll,
     dragging: Option<Item>,
 }
 
 impl GraphicsUi {
     pub fn reset(&mut self) {
-        self.scroll = 0.0;
+        self.scroll = ui::Scroll::default();
         self.dragging = None;
     }
+    /// The scrollbar's column: right of the descriptions.
+    fn scrollbar_x(w: f32) -> f32 {
+        STYLE.row_x(w) + STYLE.control_width + STYLE.gap + STYLE.text_width(w) + 6.0
+    }
     fn bounds(h: f32) -> (f32, f32) {
         (STYLE.band, h - STYLE.band)
     }
@@ -657,7 +674,7 @@ impl GraphicsUi {
         self.clamp_scroll(h, content);
         let (top, _) = Self::bounds(h);
         let x = STYLE.row_x(w);
-        let mut y = top + 4.0 - self.scroll;
+        let mut y = top + 4.0 - self.scroll.amount;
         let mut widgets = Vec::new();
         let mut headers = Vec::new();
         for row in extra_rows(level, s) {
@@ -702,7 +719,7 @@ impl GraphicsUi {
     }
     fn clamp_scroll(&mut self, h: f32, content: f32) {
         let (top, bottom) = Self::bounds(h);
-        self.scroll = self.scroll.clamp(0.0, (content - (bottom - top)).max(0.0));
+        self.scroll.clamp(top, bottom, content);
     }
     pub fn draw(
         &mut self,
@@ -799,11 +816,11 @@ impl GraphicsUi {
         ui::scrollbar(
             batch,
             atlas,
-            x + STYLE.control_width + STYLE.gap + STYLE.text_width(w) + 6.0,
+            Self::scrollbar_x(w),
             top,
             bottom,
             content,
-            self.scroll,
+            self.scroll.amount,
         );
         let title = match level {
             Level::Simple => "Graphics",
@@ -825,9 +842,14 @@ impl GraphicsUi {
         drag: bool,
         right: bool,
     ) -> Vec<Action> {
-        let (widgets, _, _) = self.layout(level, s, w, h);
+        let (widgets, _, content) = self.layout(level, s, w, h);
         let (top, bottom) = Self::bounds(h);
         if drag {
+            // AbstractScrollArea.mouseDragged: the held scrollbar follows the pointer.
+            if self.scroll.held() {
+                self.scroll.drag(y, top, bottom, content);
+                return Vec::new();
+            }
             if let Some(item) = self.dragging
                 && let Some(wd) = widgets
                     .iter()
@@ -841,6 +863,13 @@ impl GraphicsUi {
         if right {
             return Vec::new();
         }
+        // AbstractScrollArea.updateScrolling: a press on the scrollbar holds it, silently.
+        if self
+            .scroll
+            .press((x, y), Self::scrollbar_x(w), top, bottom, content)
+        {
+            return Vec::new();
+        }
         for wd in widgets {
             if !ui::hovered((x, y), wd.x, wd.y, wd.w, 20.0) {
                 continue;
@@ -866,14 +895,16 @@ impl GraphicsUi {
         }
         Vec::new()
     }
+    /// Lets go of a slider (true: it plays its click) or the scrollbar.
     pub fn release(&mut self) -> bool {
+        self.scroll.release();
         self.dragging.take().is_some()
     }
     pub fn scroll(&mut self, level: Level, s: &Settings, h: f32, amount: f32) {
         let content = Self::content_height(level, s);
-        self.clamp_scroll(h, content);
-        self.scroll -= amount * 18.0;
-        self.clamp_scroll(h, content);
+        let (top, bottom) = Self::bounds(h);
+        self.scroll.clamp(top, bottom, content);
+        self.scroll.wheel(amount, 18.0, top, bottom, content);
     }
 }
 
@@ -960,29 +991,68 @@ mod tests {
             assert!(max > 4.5);
             for _ in 0..3 {
                 ui.scroll(level, &s, h, 1000.0);
-                assert_eq!(ui.scroll, 0.0);
+                assert_eq!(ui.scroll.amount, 0.0);
             }
             for _ in 0..3 {
                 ui.scroll(level, &s, h, -1000.0);
-                assert_eq!(ui.scroll, max);
+                assert_eq!(ui.scroll.amount, max);
             }
             ui.scroll(level, &s, h, 0.25);
-            assert_eq!(ui.scroll, max - 4.5);
+            assert_eq!(ui.scroll.amount, max - 4.5);
             ui.scroll(level, &s, h, 1000.0);
             ui.scroll(level, &s, h, -0.25);
-            assert_eq!(ui.scroll, 4.5);
+            assert_eq!(ui.scroll.amount, 4.5);
         }
     }
 
+    #[test]
+    fn the_scrollbar_can_be_held_and_dragged() {
+        // #3552: AbstractScrollArea.updateScrolling holds the scrollbar on a press over its
+        // column, mouseDragged moves the list with the pointer, onRelease lets go.
+        let mut s = Settings::default();
+        let size = (480.0, 2.0 * STYLE.band + 60.0);
+        let (top, bottom) = GraphicsUi::bounds(size.1);
+        // On the scrollbar column, as `draw` paints it.
+        let x =
+            STYLE.row_x(size.0) + STYLE.control_width + STYLE.gap + STYLE.text_width(size.0) + 8.0;
+        let first_row = |ui: &mut GraphicsUi| {
+            ui.layout(Level::Advanced, &Settings::default(), size.0, size.1)
+                .0[0]
+                .y
+        };
+        let mut ui = GraphicsUi::default();
+        let start = first_row(&mut ui);
+        let at = |y| (x, y);
+        let press = |ui: &mut GraphicsUi, s: &mut Settings, y, drag| {
+            ui.click(Level::Advanced, s, at(y), size, [854, 480], drag, false)
+        };
+        // The press itself makes no sound and changes nothing.
+        assert!(press(&mut ui, &mut s, top + 5.0, false).is_empty());
+        assert!(press(&mut ui, &mut s, top + 15.0, true).is_empty());
+        let moved = first_row(&mut ui);
+        assert!(moved < start, "dragging down scrolls the list down");
+        // Past the bottom of the list: the last row.
+        press(&mut ui, &mut s, bottom + 50.0, true);
+        let content = GraphicsUi::content_height(Level::Advanced, &s);
+        assert_eq!(first_row(&mut ui), start - (content - (bottom - top)));
+        // Above the list: the first row again.
+        press(&mut ui, &mut s, top - 50.0, true);
+        assert_eq!(first_row(&mut ui), start);
+        // Released: drags no longer scroll, and no slider click plays.
+        assert!(!ui.release());
+        press(&mut ui, &mut s, bottom + 50.0, true);
+        assert_eq!(first_row(&mut ui), start);
+    }
+
     #[test]
     fn resizing_clamps_before_positioning_graphics_rows() {
         let s = Settings::default();
         for level in [Level::Simple, Level::Advanced] {
             let mut ui = GraphicsUi::default();
             ui.scroll(level, &s, 2.0 * STYLE.band + 10.0, -1000.0);
-            assert!(ui.scroll > 0.0);
+            assert!(ui.scroll.amount > 0.0);
             let (widgets, headers, _) = ui.layout(level, &s, 480.0, 4000.0);
-            assert_eq!(ui.scroll, 0.0);
+            assert_eq!(ui.scroll.amount, 0.0);
             if let Some((y, _)) = headers.first() {
                 assert_eq!(*y, STYLE.band + 4.0);
             }
@@ -992,7 +1062,7 @@ mod tests {
                 expected.iter().map(|w| w.y).collect::<Vec<_>>()
             );
             ui.scroll(level, &s, 4000.0, -1000.0);
-            assert_eq!(ui.scroll, 0.0);
+            assert_eq!(ui.scroll.amount, 0.0);
         }
     }
 

crates/horizon-client-render/src/hdr.wgsl

@@ -16,6 +16,8 @@ struct Params {
     debug: f32,
     // 1 for an HDR10 swapchain, 0 for scRGB.
     pq: f32,
+    // The display's black level in nits; 0 leaves the picture as it is.
+    black: f32,
 };
 @group(0) @binding(2) var<uniform> params: Params;
 
@@ -56,6 +58,23 @@ fn pq(nits: vec3<f32>) -> vec3<f32> {
     return pow((0.8359375 + 18.8515625 * y) / (1.0 + 18.6875 * y), vec3(78.84375));
 }
 
+// ST 2084's inverse: the PQ signal to nits.
+fn pq_nits(e: vec3<f32>) -> vec3<f32> {
+    let p = pow(clamp(e, vec3(0.0), vec3(1.0)), vec3(1.0 / 78.84375));
+    let y = max(p - 0.8359375, vec3(0.0)) / (18.8515625 - 18.6875 * p);
+    return 10000.0 * pow(y, vec3(1.0 / 0.1593017578125));
+}
+
+// ITU-R BT.2390's black level lift (its EETF without the knee) on the PQ signal
+// `e`: black moves up to the display's black level, the peak stays, and the lift
+// fades out by the fourth power on the way up, so only the shadows move. A display
+// that can't go darker than its black level would crush everything below it.
+fn lift_black(e: vec3<f32>) -> vec3<f32> {
+    let top = pq(vec3(params.peak * params.paper * 80.0)).x;
+    let n = min(e / top, vec3(1.0));
+    return e + pq(vec3(params.black)).x * pow(vec3(1.0) - n, vec3(4.0));
+}
+
 @vertex fn vs_hdr(@builtin(vertex_index) i: u32) -> @builtin(position) vec4<f32> {
     let p = vec2<f32>(f32((i << 1u) & 2u), f32(i & 2u));
     return vec4(p * 2.0 - 1.0, 0.0, 1.0);
@@ -86,7 +105,11 @@ fn pq(nits: vec3<f32>) -> vec3<f32> {
     }
     let scrgb = light * params.paper;
     if params.pq > 0.5 {
-        return vec4(pq(BT709_TO_BT2020 * scrgb * 80.0), 1.0);
+        let e = pq(BT709_TO_BT2020 * scrgb * 80.0);
+        return vec4(select(e, lift_black(e), params.black > 0.0), 1.0);
+    }
+    if params.black > 0.0 {
+        return vec4(pq_nits(lift_black(pq(scrgb * 80.0))) / 80.0, 1.0);
     }
     return vec4(scrgb, 1.0);
 }

crates/horizon-client-render/src/hud.rs

@@ -1162,6 +1162,33 @@ impl HudBatch {
         }
         cursor - x
     }
+    /// SubmitNodeCollection.submitNameTag's text in its own space (x right,
+    /// y down, in GUI pixels): centred at `-Font.width / 2`, drawn as
+    /// Font.prepareText draws any text (styles, fonts and glyph boxes; no
+    /// shadow), over `background` (RGBA) unless its alpha is 0. Returns how
+    /// many vertices at the start of the batch are the background.
+    pub fn name_tag(
+        &mut self,
+        atlas: &HudAtlas,
+        text: &crate::text::Text,
+        y: f32,
+        color: u32,
+        background: u32,
+    ) -> usize {
+        let x = -atlas.font.width_text(text) / 2.0;
+        let start = self.vertices.len();
+        let advance = self.text_styled(atlas, text, x, y, color, false);
+        if background >> 24 == 0 {
+            return 0;
+        }
+        // PreparedTextBuilder.markBackground: one pixel round the advances,
+        // from a pixel above the line to 9 below its top.
+        let glyphs = self.vertices.split_off(start);
+        self.fill(atlas, x - 1.0, y - 1.0, advance + 1.0, 10.0, background);
+        let behind = self.vertices.len() - start;
+        self.vertices.extend(glyphs);
+        behind
+    }
 }
 #[repr(C)]
 #[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
@@ -1877,6 +1904,65 @@ mod tests {
         assert!(missing.rect.is_none() && missing.right == 5.0);
     }
 
+    #[test]
+    fn name_tags_draw_bold_text_and_tall_glyphs_like_any_text() {
+        // `ascii.png`'s 8x8 'a' (4 pixels wide) and `accented.png`'s 9x12
+        // 'й' (height 12, ascent 10: the breve above the line), 7 wide.
+        let root = std::env::temp_dir().join(format!("horizon-name-tag-{}", std::process::id()));
+        let textures = root.join("assets/minecraft/textures/font");
+        fs::create_dir_all(root.join("assets/minecraft/font")).unwrap();
+        fs::create_dir_all(&textures).unwrap();
+        fs::write(
+            root.join("assets/minecraft/font/default.json"),
+            r#"{"providers":[
+                {"type":"bitmap","file":"minecraft:font/a.png","ascent":7,"chars":["a"]},
+                {"type":"bitmap","file":"minecraft:font/tall.png","height":12,"ascent":10,"chars":["й"]}]}"#,
+        )
+        .unwrap();
+        for (name, (w, h), used) in [("a", (8, 8), 4), ("tall", (9, 12), 7)] {
+            let pixels: Vec<u8> = (0..w * h)
+                .flat_map(|i| [255, 255, 255, if i % w < used { 255 } else { 0 }])
+                .collect();
+            let file = fs::File::create(textures.join(format!("{name}.png"))).unwrap();
+            let mut encoder = png::Encoder::new(file, w, h);
+            encoder.set_color(png::ColorType::Rgba);
+            encoder.set_depth(png::BitDepth::Eight);
+            let mut writer = encoder.write_header().unwrap();
+            writer.write_image_data(&pixels).unwrap();
+        }
+        let atlas = HudAtlas::build(&root).unwrap();
+        let _ = fs::remove_dir_all(&root);
+        let text = crate::text::Text::literal("aй").bold();
+        let mut batch = HudBatch::new([1, 1]);
+        let behind = batch.name_tag(&atlas, &text, 0.0, u32::MAX, 0x3F00_0000);
+        // Each quad's box: x0, y0, x1, y1.
+        let boxes: Vec<[f32; 4]> = batch
+            .vertices
+            .as_chunks::<6>()
+            .0
+            .iter()
+            .map(|q| [q[0].pos[0], q[0].pos[1], q[2].pos[0], q[2].pos[1]])
+            .collect();
+        // Advances 5 and 8, plus 1 each for bold: Font.width 15, centred.
+        let x = -7.5;
+        // Each glyph twice (bold), the copy a pixel right; 'й' in its 9x12
+        // box from 3 pixels above the line, each bold quad 0.1 larger.
+        let near = |a: [f32; 4], b: [f32; 4]| a.iter().zip(b).all(|(a, b)| (a - b).abs() < 1e-4);
+        let expected = [
+            [x - 0.1, -0.1, x + 8.1, 8.1],
+            [x + 0.9, -0.1, x + 9.1, 8.1],
+            [x + 5.9, -3.1, x + 15.1, 9.1],
+            [x + 6.9, -3.1, x + 16.1, 9.1],
+        ];
+        for (got, want) in boxes[1..].iter().zip(expected) {
+            assert!(near(*got, want), "{got:?} != {want:?}");
+        }
+        assert_eq!(boxes.len(), 1 + expected.len());
+        // The background first: a pixel round the advances, 10 pixels tall.
+        assert_eq!(behind, 6);
+        assert_eq!(boxes[0], [x - 1.0, -1.0, x + 15.0, 9.0]);
+    }
+
     #[test]
     fn effect_icons_are_painted_from_the_mob_effect_directory() {
         use crate::{effects::EffectInstance, hud_layout, hud_overlays, inventory_effects};

crates/horizon-client-render/src/lib.rs

@@ -70,6 +70,7 @@ pub mod skins;
 pub mod sound_engine;
 pub mod sound_events;
 pub mod spans;
+pub mod split_layout;
 mod sprite_cache;
 pub mod sprites;
 pub mod streaming;

crates/horizon-client-render/src/lod.rs

@@ -25,6 +25,16 @@ const MAX_SAVED: usize = 1024;
 /// (`Lod::observing`).
 pub const OBSERVE_AHEAD: usize = 8;
 const SAMPLE_JOBS: usize = 4;
+/// Threads that sample far tiles beside the mesher. Machines with 12 or more
+/// threads use up to 6 (measured: a cold 1024-chunk LoD loads about a quarter
+/// sooner than with 3); the rest keep a quarter of their threads, at most 3.
+fn sampling_threads(cores: usize) -> usize {
+    if cores >= 12 {
+        (cores / 2).min(6)
+    } else {
+        (cores / 4).clamp(1, 3)
+    }
+}
 /// While the near terrain loads on a machine with four threads or fewer, far
 /// terrain starts one sample job at most this often and no detail: it would
 /// otherwise take the cores the near chunks and the frame need.
@@ -425,6 +435,28 @@ impl Plan {
             false
         }
     }
+    /// Whether chunk column (x, z) is drawn by the tile planned there (ready;
+    /// at level 0, also `filled`) rather than by a coarser ancestor standing
+    /// in for it, or is past the far terrain.
+    fn replaces(
+        &self,
+        (x, z): (i32, i32),
+        ready: &FxHashMap<TileKey, impl Sized>,
+        filled: impl Fn(TileKey) -> bool,
+    ) -> bool {
+        let Some(key) = (0..=MAX_LEVEL)
+            .map(|level| TileKey {
+                x: (x * 16).div_euclid(16 << level),
+                z: (z * 16).div_euclid(16 << level),
+                level,
+            })
+            .find(|key| self.nodes.contains(key))
+        else {
+            return true;
+        };
+        // A split node's child there is out of range: nothing is drawn.
+        self.split.contains(&key) || (ready.contains_key(&key) && (key.level > 0 || filled(key)))
+    }
 }
 /// Visited chunks' summaries (`Lod::saved`) and their reductions.
 type Saved = FxHashMap<(i32, i32), Arc<[Column; 256]>>;
@@ -524,6 +556,8 @@ struct Shared {
     kinds: std::sync::OnceLock<Vec<u8>>,
     wake: Condvar,
     stop: AtomicBool,
+    /// Reduced far detail: samplers approximate wide cells.
+    approximate: AtomicBool,
 }
 /// One background worker and at most two outstanding sample jobs. Only the
 /// current view's quadtree and a bounded set of visited summaries are retained.
@@ -550,6 +584,8 @@ pub struct Lod {
     detail_request_at: std::time::Instant,
     /// Four threads or fewer: far work waits for the near terrain (`hold`).
     small: bool,
+    /// Sample jobs that may be queued or running at once.
+    sample_jobs: usize,
     /// The near terrain is loading (`set_near_loading`).
     near_loading: bool,
     /// When `request_samples` last started a job while held.
@@ -559,8 +595,17 @@ pub struct Lod {
     active: FxHashSet<TileKey>,
     dirty: FxHashSet<TileKey>,
     removed: Vec<TileKey>,
+    /// The columns left out: `full` and `retiring`.
     covered: FxHashSet<(i32, i32)>,
     covered_bounds: Option<[i32; 4]>,
+    /// The full-detail columns `update` was last given.
+    full: FxHashSet<(i32, i32)>,
+    /// Columns that left the full-detail area, still left out (their
+    /// full-detail meshes still drawn) until the tile planned there is ready
+    /// (`Plan::replaces`). Tiles inside that area are never sampled: when the
+    /// render distance shrinks, their coarsest ancestors would otherwise
+    /// stand in for it for minutes.
+    retiring: FxHashSet<(i32, i32)>,
     /// The covered columns the active meshes leave out, when a mesh job
     /// has finished since the last `take_cutout`.
     cutout: Option<FxHashSet<(i32, i32)>>,
@@ -570,12 +615,14 @@ pub struct Lod {
 }
 impl Lod {
     pub fn new(source: Arc<dyn LodSource>, context: Arc<WorkerContext>) -> Self {
+        let cores = thread::available_parallelism().map_or(1, |n| n.get());
         let shared = Arc::new(Shared {
             jobs: Mutex::new(VecDeque::new()),
             observed: Mutex::new(FxHashMap::default()),
             kinds: std::sync::OnceLock::new(),
             wake: Condvar::new(),
             stop: AtomicBool::new(false),
+            approximate: AtomicBool::new(false),
         });
         let worker = shared.clone();
         let mesh_context = context.clone();
@@ -583,10 +630,10 @@ impl Lod {
         let handle = thread::Builder::new()
             .name("Far terrain".into())
             .spawn(move || {
+                // Ticks and frames come first (horizon_threads).
+                horizon_threads::behind_server();
                 let mut sampler = source.sampler();
-                let count = thread::available_parallelism()
-                    .map_or(1, |n| n.get() / 4)
-                    .clamp(1, 3);
+                let count = sampling_threads(cores);
                 let mut sampling = Vec::new();
                 for _ in 0..count {
                     let Some(mut sample) = sampler.fork() else {
@@ -598,6 +645,7 @@ impl Lod {
                         thread::Builder::new()
                             .name("Far sampling".into())
                             .spawn(move || {
+                                horizon_threads::behind_server();
                                 loop {
                                     let key = {
                                         let mut jobs = shared.jobs.lock().unwrap();
@@ -619,6 +667,9 @@ impl Lod {
                                         }
                                     };
                                     let [x, _, z] = key.origin();
+                                    sample.set_approximate(
+                                        shared.approximate.load(Ordering::Relaxed),
+                                    );
                                     let samples =
                                         sample.grid(x, z, key.size() / CELLS as i32, CELLS);
                                     if shared.stop.load(Ordering::Relaxed) {
@@ -681,6 +732,7 @@ impl Lod {
                         }
                         Job::Sample(key) => {
                             let [x, _, z] = key.origin();
+                            sampler.set_approximate(worker.approximate.load(Ordering::Relaxed));
                             let samples = sampler.grid(x, z, key.size() / CELLS as i32, CELLS);
                             Done::Sample { key, samples }
                         }
@@ -746,7 +798,8 @@ impl Lod {
             detail_masks: FxHashMap::default(),
             detail_request_pending: false,
             detail_request_at: std::time::Instant::now(),
-            small: thread::available_parallelism().map_or(1, |n| n.get()) <= 4,
+            small: cores <= 4,
+            sample_jobs: SAMPLE_JOBS.max(sampling_threads(cores) + 1),
             near_loading: false,
             held_sample_at: std::time::Instant::now(),
             ready: FxHashMap::default(),
@@ -755,6 +808,8 @@ impl Lod {
             removed: Vec::new(),
             covered: FxHashSet::default(),
             covered_bounds: None,
+            full: FxHashSet::default(),
+            retiring: FxHashSet::default(),
             cutout: None,
             saved: FxHashMap::default(),
             reduced: FxHashMap::default(),
@@ -976,9 +1031,11 @@ impl Lod {
         self.near_loading = loading;
     }
     /// Reduced far detail (`graphics::FarDetail::Reduced`): the next update
-    /// replans when it changes.
+    /// replans when it changes, and tiles sampled from then on approximate
+    /// wide cells (`GeneratorWorker::lod_grid`).
     pub fn set_reduced_detail(&mut self, reduced: bool) {
         self.reduced_detail = reduced;
+        self.shared.approximate.store(reduced, Ordering::Relaxed);
     }
     fn held(&self) -> bool {
         self.small && self.near_loading
@@ -1014,7 +1071,8 @@ impl Lod {
                         (ox + (index as i32 % 16) * stride).div_euclid(16),
                         (oz + (index as i32 / 16) * stride).div_euclid(16),
                     );
-                    if self.covered.contains(&chunk) {
+                    // A retiring column's tile is drawn soon: it needs its detail.
+                    if self.full.contains(&chunk) {
                         self.detail_masks.entry(key).or_default()[index / 64] |= 1 << (index % 64);
                     } else {
                         chunks.insert(chunk);
@@ -1136,31 +1194,13 @@ impl Lod {
     }
     /// Takes the new full-detail columns, when they changed (`None`: not).
     fn cover(&mut self, covered: Option<FxHashSet<(i32, i32)>>) {
-        if let Some(covered) = covered
-            && self.covered != covered
+        if let Some(full) = covered
+            && self.full != full
         {
-            let changes: Vec<_> = self
-                .covered
-                .symmetric_difference(&covered)
-                .copied()
-                .collect();
-            for (x, z) in changes {
-                self.invalidate_chunk(x, z);
-            }
-            self.covered_bounds = covered.iter().fold(None, |bounds, &(x, z)| {
-                Some(match bounds {
-                    None => [x * 16, z * 16, (x + 1) * 16, (z + 1) * 16],
-                    Some([x0, z0, x1, z1]) => [
-                        x0.min(x * 16),
-                        z0.min(z * 16),
-                        x1.max((x + 1) * 16),
-                        z1.max((z + 1) * 16),
-                    ],
-                })
-            });
-            self.covered = covered;
-            self.replanned = true;
-            self.reselect = true;
+            self.retiring.extend(self.full.difference(&full).copied());
+            self.retiring.retain(|column| !full.contains(column));
+            self.full = full;
+            self.leave_out();
         }
         // Complete resident columns need no duplicate noise work. Their real
         // summaries are retained when the full-detail chunks leave the view.
@@ -1174,12 +1214,55 @@ impl Lod {
             }
         }
     }
+    /// Leaves out the full-detail and retiring columns: the tiles touching
+    /// one that changed are meshed again.
+    fn leave_out(&mut self) {
+        let covered: FxHashSet<_> = self.full.union(&self.retiring).copied().collect();
+        if self.covered == covered {
+            return;
+        }
+        let changes: Vec<_> = self
+            .covered
+            .symmetric_difference(&covered)
+            .copied()
+            .collect();
+        for (x, z) in changes {
+            self.invalidate_chunk(x, z);
+        }
+        self.covered_bounds = covered.iter().fold(None, |bounds, &(x, z)| {
+            Some(match bounds {
+                None => [x * 16, z * 16, (x + 1) * 16, (z + 1) * 16],
+                Some([x0, z0, x1, z1]) => [
+                    x0.min(x * 16),
+                    z0.min(z * 16),
+                    x1.max((x + 1) * 16),
+                    z1.max((z + 1) * 16),
+                ],
+            })
+        });
+        // Only new covered columns need stand-ins.
+        self.replanned |= !covered.is_subset(&self.covered);
+        self.covered = covered;
+        self.reselect = true;
+    }
     /// Chooses the tiles to draw and meshes those that changed, when the
     /// plan, the samples, the covered columns or the active tiles changed.
     fn select(&mut self) {
         if !std::mem::take(&mut self.reselect) && self.dirty.is_empty() {
             return;
         }
+        if !self.retiring.is_empty() {
+            let (plan, ready, saved, masks) =
+                (&self.plan, &self.ready, &self.saved, &self.detail_masks);
+            // A level-0 tile there is an empty stand-in (`cover`) until the
+            // chunk's summary or generated detail fills it (`apply_fine`).
+            self.retiring.retain(|&column| {
+                !plan.replaces(column, ready, |key| {
+                    saved.contains_key(&column) || masks.get(&key) == Some(&[u64::MAX; 4])
+                })
+            });
+            self.leave_out();
+        }
         {
             let mut selected = Vec::new();
             for &key in &self.plan.roots {
@@ -1243,7 +1326,13 @@ impl Lod {
                 self.pending.is_empty() && self.held_sample_at.elapsed() >= HELD_SAMPLE_STEP,
             )
         } else {
-            SAMPLE_JOBS.saturating_sub(self.pending.len())
+            // The extra sampling threads wait until the near terrain is in.
+            let slots = if self.near_loading {
+                SAMPLE_JOBS
+            } else {
+                self.sample_jobs
+            };
+            slots.saturating_sub(self.pending.len())
         };
         if free == 0 {
             return;
@@ -1291,8 +1380,8 @@ impl Lod {
         }
         // Only the first `free` keys not already pending are taken. A key is
         // listed at most twice (as a root and as a node), so the best
-        // `2 * (SAMPLE_JOBS + pending)` entries hold them, in order.
-        let best = 2 * (SAMPLE_JOBS + self.pending.len());
+        // `2 * (sample_jobs + pending)` entries hold them, in order.
+        let best = 2 * (self.sample_jobs + self.pending.len());
         if wanted.len() > best {
             wanted.select_nth_unstable(best);
             wanted.truncate(best);
@@ -1590,6 +1679,48 @@ mod tests {
         assert_eq!(selected, parent.children());
     }
     #[test]
+    fn a_shrunk_render_distance_keeps_columns_until_their_planned_tiles_are_ready() {
+        // Render distance 64 under LOD 64: every tile inside it is a level-0
+        // stand-in for a covered column, and only the roots are sampled.
+        let camera = [8, 8];
+        let before = Plan::new(camera, 64, 64);
+        let after = Plan::with_previous(camera, 8, 64, &before, 0, false);
+        let mut ready: FxHashMap<TileKey, ()> = before
+            .nodes
+            .iter()
+            .filter(|key| key.level == 0 || before.roots.contains(key))
+            .map(|&key| (key, ()))
+            .collect();
+        ready.retain(|key, _| after.nodes.contains(key));
+        let contains = |key: &TileKey, (x, z): (i32, i32)| {
+            let [ox, _, oz] = key.origin();
+            (ox..ox + key.size()).contains(&(x * 16)) && (oz..oz + key.size()).contains(&(z * 16))
+        };
+        // 24 chunks out, now past the render distance: its planned tile was
+        // split before, so never sampled, and a root stands in for it.
+        let column = (24, 0);
+        let mut selected = Vec::new();
+        for &root in &after.roots {
+            after.select(root, &ready, &mut selected);
+        }
+        let drawn = selected.iter().filter(|key| contains(key, column));
+        assert_eq!(drawn.map(|key| key.level).min(), Some(6));
+        assert!(!after.replaces(column, &ready, |_| true));
+        let planned = TileKey {
+            x: 12,
+            z: 0,
+            level: 1,
+        };
+        assert!(after.nodes.contains(&planned) && before.split.contains(&planned));
+        ready.insert(planned, ());
+        assert!(after.replaces(column, &ready, |_| true));
+        // 12 chunks out, its level-0 tile is the stand-in until filled.
+        assert!(!after.replaces((12, 0), &ready, |_| false));
+        assert!(after.replaces((12, 0), &ready, |_| true));
+        // Past the far terrain nothing waits.
+        assert!(after.replaces((100, 0), &ready, |_| false));
+    }
+    #[test]
     fn detail_survives_movement_across_a_split_threshold() {
         let before = Plan::new([0, 0], 2, 256);
         let after = Plan::with_previous([16, 0], 2, 256, &before, 0, false);
@@ -2000,6 +2131,7 @@ mod tests {
         lod.ready
             .insert(parent, Arc::new(vec![Column::default(); 256]));
         lod.active = [parent].into_iter().collect();
+        lod.sample_jobs = SAMPLE_JOBS;
         lod.pending = (0..SAMPLE_JOBS - 1)
             .map(|i| TileKey {
                 x: 999 + i as i32,
@@ -2058,6 +2190,7 @@ mod tests {
         }
         lod.active = [near, far].into_iter().collect();
         lod.shared.jobs.lock().unwrap().clear();
+        lod.sample_jobs = SAMPLE_JOBS;
         lod.pending = (0..SAMPLE_JOBS - 1)
             .map(|i| TileKey {
                 x: 999 + i as i32,
@@ -2091,6 +2224,34 @@ mod tests {
             (1..=32).map(|x| (x, 0)).collect::<Vec<_>>(),
             "one unfinished fine tile must not starve neighbouring requests"
         );
+
+        // The extra sampling threads' slots open once the near terrain is in.
+        lod.small = false;
+        lod.sample_jobs = SAMPLE_JOBS + 3;
+        lod.plan = Plan::new([-256, -256], 2, 64);
+        lod.ready.clear();
+        lod.active.clear();
+        lod.pending.clear();
+        lod.meshing = true;
+        lod.shared.jobs.lock().unwrap().clear();
+        let queued = |lod: &mut Lod, near_loading: bool| {
+            lod.set_near_loading(near_loading);
+            lod.shared.jobs.lock().unwrap().clear();
+            lod.pending.clear();
+            lod.update([-256., 64., -256.], 0., 2, 64, Some(FxHashSet::default()));
+            let jobs = lod.shared.jobs.lock().unwrap();
+            jobs.iter()
+                .filter(|job| matches!(job, Job::Sample(_)))
+                .count()
+        };
+        assert_eq!(queued(&mut lod, true), SAMPLE_JOBS);
+        assert_eq!(queued(&mut lod, false), SAMPLE_JOBS + 3);
         Ok(())
     }
+
+    #[test]
+    fn extra_sampling_threads_only_on_large_machines() {
+        assert_eq!([1, 2, 4, 8, 11].map(sampling_threads), [1, 1, 1, 2, 2]);
+        assert_eq!([12, 16, 64].map(sampling_threads), [6, 6, 6]);
+    }
 }

crates/horizon-client-render/src/mesher.rs

@@ -513,6 +513,56 @@ impl MeshTables {
         let mut tints = Tints::new(region, biomes, zoom, blend_radius, origin);
         Mesher::tint(info, 0, &mut tints, [x & 15, y & 15, z & 15])
     }
+    /// `BlockColors` for each of the state's tint indices at `pos`, as the
+    /// chunk mesher tints them (grass blocks included): `None` for an
+    /// untinted (-1) layer. For block models drawn outside the chunk mesh.
+    pub fn block_tints(
+        &self,
+        state: BlockStateId,
+        pos: [i32; 3],
+        region: &[[Option<&Chunk>; 3]; 3],
+        biomes: &Biomes,
+        zoom: BiomeZoom,
+        blend_radius: i32,
+    ) -> impl Fn(i32) -> Option<u32> + use<> {
+        let sources = self.info.get(state.0 as usize).map(|info| {
+            let [x, y, z] = pos;
+            let origin = [x >> 4, z >> 4, y & !15];
+            let mut tints = Tints::new(region, biomes, zoom, blend_radius, origin);
+            let local = [x & 15, y & 15, z & 15];
+            let colors = [0, 1].map(|i| Mesher::tint(info, i, &mut tints, local));
+            (colors, i32::from(info.tint_count))
+        });
+        move |index| {
+            let (colors, count) = sources?;
+            if index < 0 || index >= count {
+                return None;
+            }
+            colors[(index as usize).min(1)]
+        }
+    }
+    /// `ModelBlockRenderer.tesselateFlat`'s light coords (`LightCoordsUtil`
+    /// packing, the quad's own emission included) for `quad` of `state`
+    /// drawn as the only block at `pos`, as `MovingBlockRenderState` gives
+    /// it: `light` is the world's stored light (sky << 4 | block) at a
+    /// position. For block models drawn outside the chunk mesh.
+    pub fn flat_light(
+        &self,
+        state: BlockStateId,
+        pos: [i32; 3],
+        quad: &horizon_assets::bake::ModelQuad,
+        light: impl Fn([i32; 3]) -> u8,
+    ) -> u32 {
+        let own = self.info.get(state.0 as usize);
+        let full = own.is_some_and(|i| i.full);
+        let at = lighting::flat_position(pos, &quad.positions, quad.facing, quad.cull, full);
+        let packed = light(at);
+        let coords = match own {
+            Some(own) => lighting::packed_coords(own, packed),
+            None => u32::from(packed & 15) << 4 | u32::from(packed >> 4) << 20,
+        };
+        lighting::with_emission(coords, quad.light_emission)
+    }
     /// `BlockState.getOffset` for blocks with a random model offset.
     pub fn offset(&self, state: BlockStateId, x: i32, z: i32) -> Option<[f64; 3]> {
         offset(self.info.get(state.0 as usize)?, x, z)

crates/horizon-client-render/src/mesher/lighting.rs

@@ -39,10 +39,13 @@ fn state<'a>(pad: &Padded, info: &'a [Info], p: [i32; 3]) -> &'a Info {
 /// `LightCoordsUtil.getLightCoords`: light at `p` as seen through `state`
 /// (block level << 4 | sky level << 20).
 pub(super) fn coords(pad: &Padded, state: &Info, p: [i32; 3]) -> u32 {
+    packed_coords(state, pad.light[pi(p[0], p[1], p[2])])
+}
+/// `coords` of a stored light byte (sky level << 4 | block level).
+pub(super) fn packed_coords(state: &Info, packed: u8) -> u32 {
     if state.emissive {
         return FULL_BRIGHT;
     }
-    let packed = pad.light[pi(p[0], p[1], p[2])];
     let block = u32::from((packed & 15).max(state.emission));
     block << 4 | u32::from(packed >> 4) << 20
 }
@@ -274,8 +277,28 @@ pub(super) fn flat(
     positions: &[[f32; 3]; 4],
     face: D,
 ) -> u32 {
-    let cubic = shape(positions, face, own.full).cubic;
-    coords(pad, own, if cubic { step(pos, face) } else { pos })
+    coords(
+        pad,
+        own,
+        flat_position(pos, positions, face, None, own.full),
+    )
+}
+/// Where `tesselateFlat` reads the light of a quad of a block at `pos`: the
+/// neighbour on its cull face, else `prepareQuadFlat`'s choice (the neighbour
+/// when the quad is cubic, else the block itself). `full` is the block's
+/// `isCollisionShapeFullBlock`.
+pub(super) fn flat_position(
+    pos: [i32; 3],
+    positions: &[[f32; 3]; 4],
+    face: D,
+    cull: Option<D>,
+    full: bool,
+) -> [i32; 3] {
+    match cull {
+        Some(d) => step(pos, d),
+        None if shape(positions, face, full).cubic => step(pos, face),
+        None => pos,
+    }
 }
 /// `prepareQuadAmbientOcclusion`: per-vertex AO brightness (before `ARGB.gray`)
 /// and smooth light coords, by vertex index.
@@ -398,6 +421,39 @@ mod tests {
         assert_eq!(max_coords(packed(3, 9), packed(7, 2)), packed(7, 9));
     }
     #[test]
+    fn flat_light_reads_the_neighbour_a_face_looks_at() {
+        let pos = [4, 64, -2];
+        let full_top = [
+            [0.0, 1.0, 0.0],
+            [0.0, 1.0, 1.0],
+            [1.0, 1.0, 1.0],
+            [1.0, 1.0, 0.0],
+        ];
+        // A cull face samples its neighbour, whatever the quad's shape.
+        let inset = full_top.map(|[x, _, z]| [x, 0.75, z]);
+        assert_eq!(
+            flat_position(pos, &inset, D::Up, Some(D::Up), false),
+            [4, 65, -2]
+        );
+        // A flush quad without a cull face samples its neighbour too: a block
+        // drawn at a cell that is now opaque (a moving block, #3002) still
+        // takes the light around it.
+        assert_eq!(
+            flat_position(pos, &full_top, D::Up, None, false),
+            [4, 65, -2]
+        );
+        let west = [
+            [0.0, 0.0, 0.0],
+            [0.0, 0.0, 1.0],
+            [0.0, 1.0, 1.0],
+            [0.0, 1.0, 0.0],
+        ];
+        assert_eq!(flat_position(pos, &west, D::West, None, false), [3, 64, -2]);
+        // An inset quad (a piston head's arm) takes the block's own light.
+        assert_eq!(flat_position(pos, &inset, D::Up, None, false), pos);
+        assert_eq!(flat_position(pos, &inset, D::Up, None, true), [4, 65, -2]);
+    }
+    #[test]
     fn quad_shape_classifies_partial_and_cubic_faces() {
         let full_top = [
             [0.0, 1.0, 0.0],

crates/horizon-client-render/src/mesher/particle_tests.rs

@@ -54,3 +54,40 @@ fn terrain_particles_use_the_particle_sprite_and_vanilla_tint_sources() {
     assert_eq!(tint("minecraft:pink_petals"), None);
     assert_eq!(tint("minecraft:stone"), None);
 }
+
+/// Blocks drawn outside the chunk mesh (moved by a piston) take the chunk
+/// mesher's per-layer tints: a grass block's top and side overlay are tinted
+/// as in the world, not left gray like its particles.
+#[test]
+fn block_tints_match_the_chunk_mesh_for_grass_blocks() {
+    let root =
+        std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("../../.local/horizon-client/26.3");
+    if !root.join("horizon-resources.json").exists() {
+        return;
+    }
+    let assets = Assets::load(&root).unwrap();
+    let render = assets.reload(&root).unwrap();
+    let facts = BlockFacts::load(&root, assets.registry).unwrap();
+    let visibility = crate::models::load_visibility(&root, assets.registry).unwrap();
+    let tables = MeshTables::new(&assets, &render, &facts, visibility).unwrap();
+    let biomes = Biomes::load(&root).unwrap();
+    let state = |name| assets.registry.default_state(name).unwrap();
+    let center = Chunk::empty(0, 0);
+    let mut region = [[None; 3]; 3];
+    region[1][1] = Some(&center);
+    let tints = |name| {
+        tables.block_tints(
+            state(name),
+            [5, 70, 9],
+            &region,
+            &biomes,
+            BiomeZoom::new(0),
+            2,
+        )
+    };
+    let grass = tints("minecraft:grass_block");
+    assert!(grass(0).is_some());
+    assert_eq!(grass(-1), None);
+    assert_eq!(tints("minecraft:spruce_leaves")(0), Some(0x61_9961));
+    assert_eq!(tints("minecraft:stone")(0), None);
+}

crates/horizon-client-render/src/options_ui.rs

@@ -84,6 +84,27 @@ pub(crate) const ACCESSIBILITY_OPTIONS: &[Opt] = &[
     Opt::HighContrastBlockOutlines,
 ];
 
+/// `ControlsScreen.options`: the controls added by Java Edition 26.3, in
+/// their vanilla order. The macOS-only Control-click switch is omitted on
+/// other platforms just as `InputQuirks.EMULATE_RIGHT_CLICK_WITH_CTRL_KEY`
+/// does in Java.
+pub(crate) fn vanilla_control_options() -> Vec<Opt> {
+    let mut options = vec![
+        Opt::ToggleCrouch,
+        Opt::ToggleSprint,
+        Opt::ToggleAttack,
+        Opt::ToggleUse,
+        Opt::AutoJump,
+        Opt::SprintWindow,
+        Opt::QuitShortcuts,
+    ];
+    if cfg!(target_os = "macos") {
+        options.push(Opt::CtrlClickEmulatesRightClick);
+    }
+    options.push(Opt::OperatorItemsTab);
+    options
+}
+
 /// `MouseSettingsScreen.options` in Java Edition 26.3, in vanilla order.
 pub(crate) const MOUSE_OPTIONS: &[Opt] = &[
     Opt::Sensitivity,
@@ -120,6 +141,11 @@ impl Opt {
                 | Opt::ChunkFade
                 | Opt::ImprovedTransparency
                 | Opt::ChunkBuilder
+                // Saved, but the creative tabs, the quit keys and the mouse
+                // don't read them yet.
+                | Opt::OperatorItemsTab
+                | Opt::QuitShortcuts
+                | Opt::CtrlClickEmulatesRightClick
         )
     }
     fn file_key(self) -> Option<&'static str> {
@@ -144,6 +170,9 @@ impl Opt {
             Opt::RotateWithMinecarts => "rotateWithMinecart",
             Opt::HighContrastBlockOutlines => "highContrastBlockOutline",
             Opt::MusicFrequency => "musicFrequency",
+            Opt::OperatorItemsTab => "operatorItemsTab",
+            Opt::QuitShortcuts => "quitShortcuts",
+            Opt::CtrlClickEmulatesRightClick => "ctrlClickEmulatesRightClick",
             Opt::ModelPart(i) => MODEL_PART_KEYS[i],
             Opt::AllowServerListing => "allowServerListing",
             Opt::RealmsNotifications => "realmsNotifications",
@@ -194,7 +223,13 @@ impl Opt {
             Opt::MenuBlur => "options.accessibility.menu_background_blurriness",
             Opt::ToggleCrouch => "key.sneak",
             Opt::ToggleSprint => "key.sprint",
+            Opt::ToggleAttack => "key.attack",
+            Opt::ToggleUse => "key.use",
             Opt::AutoJump => "options.autoJump",
+            Opt::SprintWindow => "options.sprintWindow",
+            Opt::QuitShortcuts => "options.quitShortcuts",
+            Opt::CtrlClickEmulatesRightClick => "options.ctrlClickEmulatesRightClick",
+            Opt::OperatorItemsTab => "options.operatorItemsTab",
             Opt::ChatVisibility => "options.chat.visibility",
             Opt::ChatColors => "options.chat.color",
             Opt::ChatLinks => "options.chat.links",
@@ -217,7 +252,7 @@ impl Opt {
             Opt::NotificationDisplayTime => "options.notifications.display_time",
             Opt::Narrator => "options.narrator",
             Opt::TextBackground => "options.accessibility.text_background",
-            Opt::ChatDelay => "Chat Delay",
+            Opt::ChatDelay => "horizon.options.chat_delay",
             Opt::DistortionEffects => "options.screenEffectScale",
             Opt::FovEffects => "options.fovEffectScale",
             Opt::DarknessPulsing => "options.darknessEffectScale",
@@ -308,6 +343,7 @@ impl Opt {
             Opt::PadLookSensitivity => Kind::Slider(s.controller.look_sensitivity),
             Opt::PadMoveDeadzone => unit(s.controller.move_deadzone, 0.0, 0.5),
             Opt::PadLookDeadzone => unit(s.controller.look_deadzone, 0.0, 0.5),
+            Opt::SprintWindow => unit(s.sprint_window as f32, 0.0, 10.0),
             _ => Kind::Cycle,
         }
     }
@@ -356,6 +392,14 @@ impl Opt {
                 }
             }
             Opt::PanoramaSpeed => percent(c, s.file.double("panoramaScrollSpeed") as f32),
+            Opt::SprintWindow => {
+                let value = if s.sprint_window == 0 {
+                    tr("options.off")
+                } else {
+                    Text::tr("options.value", &[&s.sprint_window])
+                };
+                generic(c, value)
+            }
             Opt::Fov => match s.fov as i32 {
                 70 => generic(c, tr("options.fov.min")),
                 110 => generic(c, tr("options.fov.max")),
@@ -573,7 +617,20 @@ impl Opt {
             } else {
                 "options.key.hold"
             }),
+            Opt::ToggleAttack => tr(if s.toggle_attack {
+                "options.key.toggle"
+            } else {
+                "options.key.hold"
+            }),
+            Opt::ToggleUse => tr(if s.toggle_use {
+                "options.key.toggle"
+            } else {
+                "options.key.hold"
+            }),
             Opt::AutoJump => on_off(s.auto_jump),
+            Opt::QuitShortcuts => on_off(s.quit_shortcuts),
+            Opt::CtrlClickEmulatesRightClick => on_off(s.ctrl_click_emulates_right_click),
+            Opt::OperatorItemsTab => on_off(s.operator_items_tab),
             Opt::ChatVisibility => tr([
                 "options.chat.visibility.full",
                 "options.chat.visibility.system",
@@ -603,25 +660,25 @@ impl Opt {
             } else {
                 "options.key.hold"
             }),
-            Opt::PadLightbar => Text::literal(match s.controller.lightbar {
-                gamepad::Lightbar::Health => "Health",
-                gamepad::Lightbar::Dimension => "Dimension",
-                gamepad::Lightbar::Off => "Off",
+            Opt::PadLightbar => tr(match s.controller.lightbar {
+                gamepad::Lightbar::Health => "horizon.options.lightbar.health",
+                gamepad::Lightbar::Dimension => "horizon.options.lightbar.dimension",
+                gamepad::Lightbar::Off => "options.off",
             }),
-            Opt::PadGlyphs => Text::literal(match s.controller.glyphs {
-                GlyphStyle::Auto => "Auto",
-                GlyphStyle::Xbox => "Xbox",
-                GlyphStyle::PlayStation => "PlayStation",
-                GlyphStyle::Nintendo => "Nintendo",
+            Opt::PadGlyphs => tr(match s.controller.glyphs {
+                GlyphStyle::Auto => "horizon.options.glyphs.auto",
+                GlyphStyle::Xbox => "horizon.options.glyphs.xbox",
+                GlyphStyle::PlayStation => "horizon.options.glyphs.playstation",
+                GlyphStyle::Nintendo => "horizon.options.glyphs.nintendo",
             }),
-            Opt::PadMenuNav => Text::literal(match s.controller.menu_nav {
-                gamepad::MenuNav::Focus => "Focus",
-                gamepad::MenuNav::Pointer => "Pointer",
+            Opt::PadMenuNav => tr(match s.controller.menu_nav {
+                gamepad::MenuNav::Focus => "horizon.options.menu_focus",
+                gamepad::MenuNav::Pointer => "horizon.options.menu_pointer",
             }),
-            Opt::PadKeyboard => Text::literal(match s.controller.keyboard {
-                gamepad::TextKeyboard::Auto => "Auto",
-                gamepad::TextKeyboard::Horizon => "Horizon",
-                gamepad::TextKeyboard::Steam => "Steam",
+            Opt::PadKeyboard => tr(match s.controller.keyboard {
+                gamepad::TextKeyboard::Auto => "horizon.options.keyboard.auto",
+                gamepad::TextKeyboard::Horizon => "horizon.options.keyboard.horizon",
+                gamepad::TextKeyboard::Steam => "horizon.options.keyboard.steam",
             }),
             _ => Text::empty(),
         }
@@ -674,6 +731,7 @@ impl Opt {
             Opt::PadLookSensitivity => s.controller.look_sensitivity = v,
             Opt::PadMoveDeadzone => s.controller.move_deadzone = step(0.0, 50.0) / 100.0,
             Opt::PadLookDeadzone => s.controller.look_deadzone = step(0.0, 50.0) / 100.0,
+            Opt::SprintWindow => s.sprint_window = step(0.0, 10.0) as i32,
             _ => {}
         }
         if self.affects_preset() {
@@ -770,7 +828,14 @@ impl Opt {
             Opt::ChunkBuilder => s.prioritize_chunk_updates = next(s.prioritize_chunk_updates, 3),
             Opt::ToggleCrouch => s.toggle_crouch = !s.toggle_crouch,
             Opt::ToggleSprint => s.toggle_sprint = !s.toggle_sprint,
+            Opt::ToggleAttack => s.toggle_attack = !s.toggle_attack,
+            Opt::ToggleUse => s.toggle_use = !s.toggle_use,
             Opt::AutoJump => s.auto_jump = !s.auto_jump,
+            Opt::QuitShortcuts => s.quit_shortcuts = !s.quit_shortcuts,
+            Opt::CtrlClickEmulatesRightClick => {
+                s.ctrl_click_emulates_right_click = !s.ctrl_click_emulates_right_click
+            }
+            Opt::OperatorItemsTab => s.operator_items_tab = !s.operator_items_tab,
             Opt::ChatVisibility => s.chat_visibility = next(s.chat_visibility, 3),
             Opt::ChatColors => s.chat_colors = !s.chat_colors,
             Opt::ChatLinks => s.chat_links = !s.chat_links,
@@ -1012,7 +1077,11 @@ pub enum Event {
     Language(String),
     /// The pack selection changed (reload resources).
     Packs(Vec<String>),
+    /// Create World's Data Packs screen closed with a new selection.
+    DataPacks(Vec<String>),
     OpenPackFolder,
+    /// Data Packs' Open Pack Folder: create the folder if needed and open it.
+    OpenDataPackFolder(std::path::PathBuf),
     OpenModFolder,
     /// The Shader Packs page opened: list `shaderpacks/` into `shader_packs`.
     ListShaderPacks,
@@ -1022,6 +1091,9 @@ pub enum Event {
     /// Open the mod's own settings page (capability `ui`): the installed
     /// mod's index in `mods.installed`.
     ModSettings(usize),
+    /// Native mod `.0`'s page opened: the game asks the mod for its labels
+    /// again (they were made with the list, maybe in another language).
+    NativeSettings(usize),
     /// Button `.1` of native mod `.0`'s page was pressed: the game tells the
     /// mod and refreshes the page.
     NativeButton(usize, usize),
@@ -1075,6 +1147,13 @@ pub struct OptionsUi {
     pub pack_selection: Vec<String>,
     /// The open pack screen, made at its first frame.
     pub pack_screen: Option<crate::pack_screen::PackScreen>,
+    /// The Packs page is Create World's Data Packs screen on this folder.
+    data_pack_dir: Option<std::path::PathBuf>,
+    /// The game's resources, for the built-in data pack's icon.
+    data_pack_resources: std::path::PathBuf,
+    /// The folder's entries when its packs were listed, and when they were
+    /// last compared with it.
+    data_pack_stamp: (Vec<(String, Option<std::time::SystemTime>)>, Instant),
     /// A reload failure, dismissed before returning to the current page.
     pub resource_error: Option<String>,
     /// When the pack screen's search box took the focus (its cursor blink).
@@ -1109,6 +1188,9 @@ impl Default for OptionsUi {
             pack_infos: Vec::new(),
             pack_selection: Vec::new(),
             pack_screen: None,
+            data_pack_dir: None,
+            data_pack_resources: Default::default(),
+            data_pack_stamp: (Vec::new(), Instant::now()),
             resource_error: None,
             pack_focus: Instant::now(),
             in_world: false,
@@ -1161,22 +1243,14 @@ fn option_widget(s: &Settings, opt: Opt, x: f32, y: f32, w: f32) -> Widget {
 /// What a button opening one of Horizon's pages says on hover.
 fn horizon_page_tooltip(page: Page) -> Option<&'static str> {
     Some(match page {
-        Page::Horizon => "Horizon's own settings: graphics, controllers, extras and mods.",
-        Page::Graphics => "Graphics, simply: each setting says what it costs.",
-        Page::GraphicsAdvanced => {
-            "Every graphics setting, Horizon's included, with what each costs."
-        }
-        Page::Controller => "Controllers: their buttons, sticks, vibration and menu navigation.",
-        Page::Extras => {
-            "Optional additions, all off by default: the game stays vanilla until you turn one on."
-        }
-        Page::Agent => "Let your own AI agent play: horizon-ctl and MCP clients on this computer.",
-        Page::ShaderPacks => {
-            "Shader packs from the shaderpacks folder: Horizon's own and those in the shaders/ format. One runs at a time."
-        }
-        Page::Mods => {
-            "Mods made for Horizon, from the horizon-mods folder. Each runs in a sandbox and stays off until you turn it on."
-        }
+        Page::Horizon => "horizon.pages.settings.tooltip",
+        Page::Graphics => "horizon.pages.graphics.tooltip",
+        Page::GraphicsAdvanced => "horizon.pages.graphics_advanced.tooltip",
+        Page::Controller => "horizon.pages.controller.tooltip",
+        Page::Extras => "horizon.pages.extras.tooltip",
+        Page::Agent => "horizon.pages.agent.tooltip",
+        Page::ShaderPacks => "horizon.pages.shader_packs.tooltip",
+        Page::Mods => "horizon.pages.mods.tooltip",
         _ => return None,
     })
 }
@@ -1216,9 +1290,48 @@ impl OptionsUi {
     pub fn open(&mut self, in_world: bool) {
         self.open_at(in_world, Page::Main);
     }
+    /// Create World's Data Packs (`openDataPackSelectionScreen`): the Packs
+    /// page on the new world's pack folder `dir`, `selected` chosen;
+    /// `resources` holds the built-in pack's icon.
+    pub fn open_data_packs(
+        &mut self,
+        dir: std::path::PathBuf,
+        selected: Vec<String>,
+        resources: std::path::PathBuf,
+    ) {
+        self.open_at(false, Page::Packs);
+        self.pack_infos = crate::datapack::screen_packs(&dir, &resources);
+        self.data_pack_resources = resources;
+        self.pack_selection = selected;
+        self.data_pack_stamp = (crate::datapack::folder_stamp(&dir), Instant::now());
+        self.data_pack_dir = Some(dir);
+    }
+    /// `PackSelectionScreen.tick`'s watcher: once a second, the Data Packs
+    /// folder's packs are listed again if it changed, the selection kept
+    /// (the search text and scroll start over).
+    fn watch_data_packs(&mut self, atlas: &HudAtlas, size: (f32, f32)) {
+        let Some(dir) = &self.data_pack_dir else {
+            return;
+        };
+        if self.data_pack_stamp.1.elapsed().as_secs() < 1 {
+            return;
+        }
+        let stamp = crate::datapack::folder_stamp(dir);
+        let changed = stamp != self.data_pack_stamp.0;
+        self.data_pack_stamp = (stamp, Instant::now());
+        if !changed {
+            return;
+        }
+        self.pack_infos = crate::datapack::screen_packs(dir, &self.data_pack_resources);
+        if let Some(p) = self.pack_screen.take() {
+            self.pack_selection = p.commit();
+            self.packs(atlas, size).changed = p.changed;
+        }
+    }
     /// Open a page whose Done/Escape returns directly to the calling screen.
     pub fn open_at(&mut self, in_world: bool, page: Page) {
         self.stack.clear();
+        self.data_pack_dir = None;
         self.push(page);
         self.in_world = in_world;
         self.selected_key = None;
@@ -1266,16 +1379,16 @@ impl OptionsUi {
             Page::Language => "options.language.title",
             Page::Font => "options.font.title",
             Page::Packs => "resourcePack.title",
-            Page::Mods => "Mods",
+            Page::Mods => "horizon.pages.mods",
             Page::NativeMod(_) => "Mod Settings",
-            Page::ShaderPacks => "Shader Packs",
+            Page::ShaderPacks => "horizon.pages.shader_packs",
             Page::Graphics | Page::GraphicsAdvanced => "options.videoTitle",
-            Page::Controller => "Controller Settings",
-            Page::PadBinds => "Controller Binds",
-            Page::Extras => "Horizon Extras",
+            Page::Controller => "horizon.pages.controller",
+            Page::PadBinds => "horizon.pages.controller_binds",
+            Page::Extras => "horizon.pages.extras",
             Page::Credits => "credits_and_attribution.screen.title",
-            Page::Horizon => "Horizon Settings",
-            Page::Agent => "AI Agent",
+            Page::Horizon => "horizon.pages.settings",
+            Page::Agent => "horizon.pages.agent",
         }
     }
     fn scrollbar_x(&self, width: f32) -> f32 {
@@ -1413,21 +1526,23 @@ impl OptionsUi {
             Page::Horizon => {
                 // Two to a row, as vanilla's OptionsList.addSmall lays out
                 // buttons; each opens a page built from vanilla's widgets.
-                let open = |label: &str, page: Page| {
-                    button(0.0, 0.0, 150.0, Text::literal(label), Act::Push(page))
-                };
+                let open =
+                    |key: &str, page: Page| button(0.0, 0.0, 150.0, tr(key), Act::Push(page));
                 vec![
                     Row::Buttons(
-                        open("Graphics...", Page::Graphics),
-                        Some(open("Advanced Graphics...", Page::GraphicsAdvanced)),
+                        open("horizon.pages.open.graphics", Page::Graphics),
+                        Some(open(
+                            "horizon.pages.open.graphics_advanced",
+                            Page::GraphicsAdvanced,
+                        )),
                     ),
                     Row::Buttons(
-                        open("Shader Packs...", Page::ShaderPacks),
-                        Some(open("Controller Settings...", Page::Controller)),
+                        open("horizon.pages.open.shader_packs", Page::ShaderPacks),
+                        Some(open("horizon.pages.open.controller", Page::Controller)),
                     ),
                     Row::Buttons(
-                        open("Extras...", Page::Extras),
-                        Some(open("Mods...", Page::Mods)),
+                        open("horizon.pages.open.extras", Page::Extras),
+                        Some(open("horizon.pages.open.mods", Page::Mods)),
                     ),
                     // No AI hides the AI Agent page and everything AI.
                     Row::Buttons(
@@ -1435,7 +1550,7 @@ impl OptionsUi {
                         Some(if s.extras.no_ai {
                             self.extra_button(s, crate::extras::Item::NoAi)
                         } else {
-                            open("AI Agent...", Page::Agent)
+                            open("horizon.pages.open.agent", Page::Agent)
                         }),
                     ),
                 ]
@@ -1454,7 +1569,7 @@ impl OptionsUi {
                         0.0,
                         0.0,
                         150.0,
-                        Text::literal("Copy Connection Details"),
+                        tr("horizon.agent.copy_details"),
                         Act::CopyAgentDetails,
                     )),
                 )];
@@ -1468,14 +1583,14 @@ impl OptionsUi {
                         0.0,
                         0.0,
                         150.0,
-                        Text::literal("Horizon Graphics..."),
+                        tr("horizon.pages.open.horizon_graphics"),
                         Act::Push(Page::Graphics),
                     ),
                     Some(button(
                         0.0,
                         0.0,
                         150.0,
-                        Text::literal("Advanced Graphics..."),
+                        tr("horizon.pages.open.graphics_advanced"),
                         Act::Push(Page::GraphicsAdvanced),
                     )),
                 )];
@@ -1559,18 +1674,15 @@ impl OptionsUi {
                         Act::Push(Page::KeyBinds),
                     )),
                 )];
-                rows.extend(pairs(&[
-                    Opt::ToggleCrouch,
-                    Opt::ToggleSprint,
-                    Opt::AutoJump,
-                ]));
+                let controls = vanilla_control_options();
+                rows.extend(pairs(&controls));
                 // Horizon's controller page, after vanilla's rows.
                 rows.push(Row::Buttons(
                     button(
                         0.0,
                         0.0,
                         310.0,
-                        Text::literal("Controller Settings..."),
+                        tr("horizon.pages.open.controller"),
                         Act::Push(Page::Controller),
                     ),
                     None,
@@ -1583,7 +1695,7 @@ impl OptionsUi {
                         0.0,
                         0.0,
                         310.0,
-                        Text::literal("Controller Binds..."),
+                        tr("horizon.pages.open.controller_binds"),
                         Act::Push(Page::PadBinds),
                     ),
                     None,
@@ -1641,9 +1753,7 @@ impl OptionsUi {
             Page::Font => pairs(&[Opt::ForceUnicode, Opt::JapaneseGlyphs]),
             Page::Mods => {
                 if s.mods.installed.is_empty() {
-                    return vec![Row::Header(
-                        "No mods: put .hmod files in the horizon-mods folder",
-                    )];
+                    return vec![Row::Header("horizon.mods.empty")];
                 }
                 s.mods
                     .installed
@@ -1653,9 +1763,9 @@ impl OptionsUi {
                         let mut label = Text::literal(format!("{}: ", installed.title))
                             .append(on_off(s.mods.is_on(i)));
                         if installed.problem.is_some() {
-                            label = label.append(" (Stopped)");
+                            label = label.append(tr("horizon.mods.stopped"));
                         } else if installed.dev {
-                            label = label.append(" (Dev)");
+                            label = label.append(tr("horizon.mods.dev"));
                         }
                         let dead = installed.dev || installed.id.is_empty();
                         // A running mod with a settings page (capability
@@ -1666,7 +1776,7 @@ impl OptionsUi {
                                 0.0,
                                 0.0,
                                 150.0,
-                                Text::literal("Settings"),
+                                tr("horizon.mods.settings"),
                                 Act::ModSettings(i),
                             );
                             Row::Buttons(
@@ -1683,17 +1793,17 @@ impl OptionsUi {
             Page::NativeMod(i) => self.native_rows(s, i),
             Page::ShaderPacks => {
                 if s.shader_packs.is_empty() {
-                    return vec![Row::Header(
-                        "No shader packs: put them in the shaderpacks folder",
-                    )];
+                    return vec![Row::Header("horizon.shader_packs.empty")];
                 }
                 s.shader_packs
                     .iter()
                     .enumerate()
                     .map(|(i, pack)| {
                         let kind = match pack.kind {
-                            crate::shader_pack_list::Kind::Horizon => " (Horizon)",
-                            crate::shader_pack_list::Kind::Classic => "",
+                            crate::shader_pack_list::Kind::Horizon => {
+                                lang::get("horizon.shader_packs.kind_horizon")
+                            }
+                            crate::shader_pack_list::Kind::Classic => String::new(),
                         };
                         let label = Text::literal(format!("{}{kind}: ", pack.title))
                             .append(on_off(s.horizon.shader_pack == pack.file));
@@ -1753,8 +1863,8 @@ impl OptionsUi {
                     // Vanilla's Telemetry Data and Credits slots: Horizon's
                     // settings and its mods, as a mod adds its button here.
                     // Credits & Attribution (WinScreen's credits) follows them.
-                    ("Horizon Settings...", Some(Page::Horizon)),
-                    ("Mods...", Some(Page::Mods)),
+                    ("horizon.pages.open.horizon_settings", Some(Page::Horizon)),
+                    ("horizon.pages.open.mods", Some(Page::Mods)),
                     ("options.credits_and_attribution", Some(Page::Credits)),
                 ];
                 let rows = entries.len().div_ceil(2) as f32;
@@ -2187,18 +2297,12 @@ impl OptionsUi {
                 content = y + self.scroll - top + 2.0;
                 out[list_start..].iter_mut().for_each(|w| w.list = true);
                 let folder = match page {
-                    Page::Mods => Some(("Open Mod Folder", Act::OpenModFolder)),
-                    Page::ShaderPacks => Some(("Open Pack Folder", Act::OpenShaderPackFolder)),
+                    Page::Mods => Some(("horizon.mods.open_folder", Act::OpenModFolder)),
+                    Page::ShaderPacks => Some(("pack.openFolder", Act::OpenShaderPackFolder)),
                     _ => None,
                 };
                 if let Some((label, act)) = folder {
-                    out.push(button(
-                        cx - 154.0,
-                        h - 27.0,
-                        150.0,
-                        Text::literal(label),
-                        act,
-                    ));
+                    out.push(button(cx - 154.0, h - 27.0, 150.0, tr(label), act));
                     out.push(button(cx + 4.0, h - 27.0, 150.0, tr("gui.done"), Act::Done));
                 } else {
                     out.push(done(h - 27.0));
@@ -2270,6 +2374,7 @@ impl OptionsUi {
             return;
         }
         if self.page() == Page::Packs {
+            self.watch_data_packs(atlas, (w, h));
             ui::menu_background(batch, atlas, 0.0, 0.0, w, h, self.in_world);
             let blink = self.pack_focus.elapsed().as_millis() as u64;
             let m = crate::screen_draw::Measure(&atlas.font);
@@ -2310,7 +2415,7 @@ impl OptionsUi {
                 } = &wd.kind
                     && let Some(text) = horizon_page_tooltip(*page)
                 {
-                    tooltip = Some(atlas.font.split(&Text::literal(text), 170.0));
+                    tooltip = Some(atlas.font.split(&tr(text), 170.0));
                 }
                 let key = match &wd.kind {
                     WKind::Button {
@@ -2337,10 +2442,7 @@ impl OptionsUi {
                 } = &wd.kind
                     && !opt.available()
                 {
-                    tooltip = Some(atlas.font.split(
-                        &Text::literal("This feature is not yet available in Horizon."),
-                        170.0,
-                    ));
+                    tooltip = Some(atlas.font.split(&tr("horizon.options.unavailable"), 170.0));
                 }
                 if let WKind::Button {
                     act: Act::ToggleMod(i),
@@ -2481,9 +2583,7 @@ impl OptionsUi {
             if search.value.is_empty() && !search.focused {
                 batch.text_styled(
                     atlas,
-                    &Text::literal("Search settings...")
-                        .with_color(text::GRAY)
-                        .italic(),
+                    &tr("horizon.options.search").with_color(text::GRAY).italic(),
                     search.text_x(),
                     search.text_y(),
                     u32::MAX,
@@ -2565,7 +2665,10 @@ impl OptionsUi {
                 self.pack_focus = Instant::now();
             }
             match action {
-                crate::pack_screen::Action::OpenFolder => events.push(Event::OpenPackFolder),
+                crate::pack_screen::Action::OpenFolder => events.push(match &self.data_pack_dir {
+                    Some(dir) => Event::OpenDataPackFolder(dir.clone()),
+                    None => Event::OpenPackFolder,
+                }),
                 crate::pack_screen::Action::Done => events.extend(self.back(s)),
                 crate::pack_screen::Action::None => {}
             }
@@ -2714,6 +2817,7 @@ impl OptionsUi {
                             events.push(Event::ButtonClick);
                             if s.mods.installed.get(i).is_some_and(|m| m.native.is_some()) {
                                 self.push(Page::NativeMod(i));
+                                events.push(Event::NativeSettings(i));
                             } else {
                                 events.push(Event::ModSettings(i));
                             }
@@ -2816,8 +2920,14 @@ impl OptionsUi {
             }
             None => {
                 self.pack_focus = Instant::now();
+                let title = if self.data_pack_dir.is_some() {
+                    "dataPack.title"
+                } else {
+                    "resourcePack.title"
+                };
                 self.pack_screen = Some(crate::pack_screen::PackScreen::new(
                     &m,
+                    crate::text::Text::translate(title, &[]),
                     w,
                     h,
                     self.in_world,
@@ -2849,13 +2959,18 @@ impl OptionsUi {
             }
             Page::Packs => {
                 // PackSelectionScreen.onClose: PackSelectionModel.commit.
+                let data = self.data_pack_dir.take();
                 if let Some(p) = self.pack_screen.take()
                     && p.changed
                 {
                     let ids = p.commit();
-                    s.resource_packs = ids.clone();
-                    self.pack_selection = ids.clone();
-                    events.push(Event::Packs(ids));
+                    if data.is_some() {
+                        events.push(Event::DataPacks(ids));
+                    } else {
+                        s.resource_packs = ids.clone();
+                        self.pack_selection = ids.clone();
+                        events.push(Event::Packs(ids));
+                    }
                 }
             }
             _ => {}
@@ -3151,6 +3266,44 @@ mod tests {
         )));
     }
 
+    #[test]
+    fn controls_match_java_26_3_option_order() {
+        let mut ui = OptionsUi::default();
+        ui.show(Page::Controls);
+        let options =
+            ui.list_rows(&Settings::default())
+                .into_iter()
+                .fold(Vec::new(), |mut options, row| {
+                    match row {
+                        Row::Big(opt) => options.push(opt),
+                        Row::Pair(a, b) => {
+                            options.push(a);
+                            options.extend(b);
+                        }
+                        _ => {}
+                    }
+                    options
+                });
+        assert_eq!(options, vanilla_control_options());
+    }
+
+    #[test]
+    fn sprint_window_and_new_control_switches_round_trip() {
+        let mut settings = Settings::default();
+        set_slider(Opt::SprintWindow, &mut settings, 0.5);
+        settings.operator_items_tab = true;
+        settings.quit_shortcuts = false;
+        settings.ctrl_click_emulates_right_click = true;
+        settings.toggle_attack = true;
+        settings.toggle_use = true;
+        let loaded = Settings::parse(&settings.serialize());
+        assert_eq!(loaded.sprint_window, 5);
+        assert!(loaded.operator_items_tab);
+        assert!(!loaded.quit_shortcuts);
+        assert!(loaded.ctrl_click_emulates_right_click);
+        assert!(loaded.toggle_attack && loaded.toggle_use);
+    }
+
     #[test]
     fn render_distance_slider_round_trips_through_extended_options_range() {
         let mut s = Settings::default();
@@ -3242,8 +3395,15 @@ mod tests {
         ui.show(Page::Mods);
         let empty = ui.layout(&s, size.0, size.1).0;
         assert!(empty.iter().any(|w| {
-            matches!(&w.kind, WKind::Text { text, .. } if text.plain().contains(".hmod"))
+            matches!(&w.kind, WKind::Text { text, .. } if text.plain() == "horizon.mods.empty")
         }));
+        // The empty page points at the bundled key; the English line behind it
+        // is what a player reads, so both halves are checked here.
+        let en = crate::lang::Language::load(&[], "en_us");
+        assert!(
+            en.get("horizon.mods.empty")
+                .is_some_and(|line| line.contains(".hmod"))
+        );
         let open_folder = empty
             .iter()
             .find(|w| {
@@ -3332,6 +3492,50 @@ mod tests {
         assert_eq!(ui.page(), Page::Main);
     }
 
+    #[test]
+    fn opening_a_native_mods_page_asks_the_game_for_its_labels_again() {
+        let atlas = atlas();
+        let mut s = Settings::default();
+        let mut ui = OptionsUi::default();
+        let size = (480.0, 240.0);
+        s.mods.installed.push(crate::mod_list::Installed {
+            id: "native".into(),
+            title: "Native 1.0".into(),
+            description: String::new(),
+            problem: None,
+            dev: false,
+            has_settings: false,
+            native: Some(crate::mod_list::NativePage::default()),
+        });
+        ui.show(Page::Mods);
+        let (widgets, ..) = ui.layout(&s, size.0, size.1);
+        let settings = widgets
+            .iter()
+            .find(|w| {
+                matches!(
+                    w.kind,
+                    WKind::Button {
+                        act: Act::ModSettings(0),
+                        ..
+                    }
+                )
+            })
+            .expect("a native mod's row has a Settings button");
+        let events = ui.click(
+            &mut s,
+            &atlas,
+            settings.x + 1.0,
+            settings.y + 1.0,
+            size,
+            [480, 240],
+            false,
+            false,
+        );
+        // Its labels were made with the list, maybe in another language.
+        assert_eq!(events.last(), Some(&Event::NativeSettings(0)));
+        assert_eq!(ui.page(), Page::NativeMod(0));
+    }
+
     #[test]
     fn option_tooltip_keys_follow_value_dependent_descriptions() {
         let mut s = Settings::default();

crates/horizon-client-render/src/pack_screen.rs

@@ -318,6 +318,8 @@ pub enum Action {
 /// The pack screen and its state.
 #[derive(Clone, Debug)]
 pub struct PackScreen {
+    /// `resourcePack.title`, or `dataPack.title` from Create World.
+    pub title: Text,
     pub width: i32,
     pub height: i32,
     pub in_world: bool,
@@ -342,6 +344,7 @@ impl PackScreen {
     /// `PackSelectionScreen.init`: the lists filled, the search box focused.
     pub fn new(
         m: &Measure,
+        title: Text,
         width: i32,
         height: i32,
         in_world: bool,
@@ -360,6 +363,7 @@ impl PackScreen {
             .filter_map(|p| Some((icon_texture(&p.id), p.icon.clone()?)))
             .collect();
         let mut s = Self {
+            title,
             width,
             height,
             in_world,
@@ -382,7 +386,7 @@ impl PackScreen {
     }
     /// The header layout: title, drop info and search box, centred.
     fn header(&self, m: &Measure) -> [(i32, i32); 3] {
-        let tw = m.width(&tr("resourcePack.title"));
+        let tw = m.width(&self.title);
         let dw = m.width(&tr("pack.dropInfo"));
         let col = tw.max(dw).max(200);
         let frame = self.width.max(col);
@@ -837,7 +841,7 @@ impl PackScreen {
             return out;
         }
         let [(tx, ty), (dx, dy), _] = self.header(m);
-        d::string_widget(&mut out, m, &tr("resourcePack.title"), tx, ty, 0);
+        d::string_widget(&mut out, m, &self.title, tx, ty, 0);
         d::string_widget(
             &mut out,
             m,
@@ -1105,7 +1109,7 @@ mod icon_tests {
             pack("high_contrast", Some(contrast.clone())),
             pack("file/Iconless", None),
         ];
-        let screen = PackScreen::new(&m, 480, 320, false, packs, &[]);
+        let screen = PackScreen::new(&m, tr("resourcePack.title"), 480, 320, false, packs, &[]);
         let mut draws = screen.draw(&m, (0, 0), 0);
         let mut patches = Vec::new();
         screen.bind_icons(&mut draws, &atlas, &mut patches);
@@ -1152,7 +1156,8 @@ mod click_sound_tests {
             crate::hud::HudAtlas::build(std::path::Path::new("/nonexistent/horizon-test-assets"))
                 .unwrap();
         let m = Measure(&atlas.font);
-        let mut screen = PackScreen::new(&m, 480, 320, false, Vec::new(), &[]);
+        let title = tr("resourcePack.title");
+        let mut screen = PackScreen::new(&m, title, 480, 320, false, Vec::new(), &[]);
         assert!(!screen.button_at(&m, 0.0, 0.0));
         assert!(!screen.button_at(
             &m,

crates/horizon-client-render/src/packs.rs

@@ -181,9 +181,15 @@ pub fn compatible(meta: &serde_json::Value) -> bool {
 /// `PackCompatibility.forVersion`: too old, too new, compatible, or unknown
 /// when the metadata names no format.
 pub fn compatibility(meta: &serde_json::Value) -> crate::pack_screen::Compat {
+    compatibility_for(meta, RESOURCE_FORMAT)
+}
+/// `compatibility` against `current`, the resource or the data pack format.
+pub fn compatibility_for(
+    meta: &serde_json::Value,
+    current: (i64, i64),
+) -> crate::pack_screen::Compat {
     use crate::pack_screen::Compat;
     let pack = &meta["pack"];
-    let current = RESOURCE_FORMAT;
     let range = if let (Some(min), Some(max)) = (
         format_of(&pack["min_format"]),
         format_of(&pack["max_format"]),
@@ -275,6 +281,10 @@ fn read_meta(source: &Source) -> Option<serde_json::Value> {
     serde_json::from_slice(&bytes).ok()
 }
 fn pack(id: String, title: Text, source: Source) -> Option<Pack> {
+    pack_for(id, title, source, RESOURCE_FORMAT)
+}
+/// A pack whose compatibility is against `format`.
+fn pack_for(id: String, title: Text, source: Source, format: (i64, i64)) -> Option<Pack> {
     let meta = read_meta(&source)?;
     let (raw_description, description_style) = component_root(&meta["pack"]["description"]);
     Some(Pack {
@@ -284,7 +294,7 @@ fn pack(id: String, title: Text, source: Source) -> Option<Pack> {
         raw_description,
         description_style,
         compatible: compatible(&meta),
-        compatibility: compatibility(&meta),
+        compatibility: compatibility_for(&meta, format),
         overlays: overlays_of(&meta),
         filter: filter_of(&meta),
         source,
@@ -305,7 +315,13 @@ pub fn discover(resources: &Path, packs_dir: &Path) -> Vec<Pack> {
             out.push(p);
         }
     }
-    let mut user: Vec<Pack> = fs::read_dir(packs_dir)
+    out.extend(folder(packs_dir, RESOURCE_FORMAT));
+    out
+}
+/// The packs (folders and zips) in `dir`, by name, as `FolderRepositorySource`
+/// finds them; their compatibility is against `format`.
+pub fn folder(dir: &Path, format: (i64, i64)) -> Vec<Pack> {
+    let mut user: Vec<Pack> = fs::read_dir(dir)
         .into_iter()
         .flatten()
         .flatten()
@@ -319,12 +335,11 @@ pub fn discover(resources: &Path, packs_dir: &Path) -> Vec<Pack> {
             } else {
                 return None;
             };
-            pack(format!("file/{name}"), Text::literal(name), source)
+            pack_for(format!("file/{name}"), Text::literal(name), source, format)
         })
         .collect();
     user.sort_by(|a, b| a.id.cmp(&b.id));
-    out.extend(user);
-    out
+    user
 }
 /// A file a pack provides: its path (folder packs) and its name inside the pack.
 type Provided = (Option<PathBuf>, String);
@@ -380,11 +395,45 @@ fn link(target: &Path, at: &Path) -> io::Result<()> {
     if target.is_dir() {
         Ok(())
     } else {
-        fs::copy(target, at).map(|_| ())
+        // The mirror only reads these files, and unix links them: a hardlink gives
+        // the same view without writing the 639 MB prepared root again, which was
+        // 33 s of a cold Windows launch with a pack on. Another volume (or a
+        // filesystem without hardlinks) still copies.
+        fs::hard_link(target, at).or_else(|_| fs::copy(target, at).map(|_| ()))
     }
 }
+/// A directory junction, which Windows creates without privileges (a directory symlink needs
+/// developer mode). The mirror falls back to copying the tree when it fails.
+#[cfg(windows)]
+fn junction(target: &Path, at: &Path) -> io::Result<()> {
+    use std::os::windows::process::CommandExt;
+    // cmd parses its own line: Rust quotes only paths with spaces, so `&` or `^` in an
+    // unquoted path would split or change the command. A Windows path cannot hold `"`.
+    let quoted = |path: &Path| -> io::Result<std::ffi::OsString> {
+        let mut quoted = std::ffi::OsString::from("\"");
+        quoted.push(std::path::absolute(path)?);
+        quoted.push("\"");
+        Ok(quoted)
+    };
+    let status = std::process::Command::new("cmd")
+        .args(["/C", "mklink", "/J"])
+        .raw_arg(quoted(at)?)
+        .raw_arg(quoted(target)?)
+        .creation_flags(0x0800_0000) // CREATE_NO_WINDOW
+        .stdout(std::process::Stdio::null())
+        .stderr(std::process::Stdio::null())
+        .status()?;
+    status
+        .success()
+        .then_some(())
+        .ok_or_else(|| io::Error::other("mklink /J failed"))
+}
+#[cfg(not(windows))]
+fn junction(_: &Path, _: &Path) -> io::Result<()> {
+    Err(io::ErrorKind::Unsupported.into())
+}
 /// Build `out` as `vanilla` with the packs' files layered on top (packs in
-/// load order, last wins). Untouched directories are symlinks into vanilla.
+/// load order, last wins). Untouched directories are links into vanilla.
 pub fn build_overlay(vanilla: &Path, packs: &[Pack], out: &Path) -> io::Result<()> {
     cache::build(vanilla, packs, out)
 }
@@ -417,6 +466,22 @@ fn build_overlay_uncached(
             files.insert(name, (i, provided));
         }
     }
+    // FallbackResourceManager: a file's `.mcmeta` counts only from the pack that
+    // supplies the file or one above it; vanilla's own sits below every pack.
+    let hidden: BTreeSet<String> = files
+        .iter()
+        .filter(|(name, _)| !name.ends_with(".mcmeta"))
+        .filter_map(|(name, (owner, _))| {
+            let meta = format!("{name}.mcmeta");
+            match files.get(&meta) {
+                Some((meta_owner, _)) if meta_owner >= owner => None,
+                _ => Some(meta),
+            }
+        })
+        .collect();
+    for name in &hidden {
+        files.remove(name);
+    }
     // Vanilla sits below every pack, so filters hide its files too.
     let filters: Vec<&Filter> = packs.iter().flat_map(|p| &p.filter).collect();
     let touched_dirs: BTreeSet<String> = files
@@ -468,6 +533,7 @@ fn build_overlay_uncached(
         vanilla: &Path,
         out: &Path,
         touched: &BTreeSet<String>,
+        hidden: &BTreeSet<String>,
         files: &BTreeMap<String, (usize, Provided)>,
         merged: &BTreeMap<String, Vec<u8>>,
         filters: &[&Filter],
@@ -504,6 +570,9 @@ fn build_overlay_uncached(
         }
         for name in names {
             let child = format!("{prefix}{name}");
+            if hidden.contains(&child) {
+                continue;
+            }
             if let Some(bytes) = merged.get(&child) {
                 fs::write(out.join(&child), bytes)?;
             } else if let Some((owner, (path, inner))) = files.get(&child) {
@@ -516,11 +585,17 @@ fn build_overlay_uncached(
                         }
                     }
                 }
+            } else if filters.is_empty()
+                && !touched.contains(&child)
+                && vanilla.join(&child).is_dir()
+                && junction(&vanilla.join(&child), &out.join(&child)).is_ok()
+            {
+                // Linked whole, like the unix symlink: no file in it is visited or copied.
             } else if touched.contains(&child)
-                // Windows cannot link a directory the way unix does (`link` above), so an
-                // untouched one has to be mirrored: skipping it hid textures/font and the
-                // title panorama from the overlay, and a font json that names those sheets
-                // then failed to load (#1688).
+                // Without a junction Windows cannot link a directory the way unix does (`link`
+                // above), so an untouched one has to be mirrored: skipping it hid textures/font
+                // and the title panorama from the overlay, and a font json that names those
+                // sheets then failed to load (#1688).
                 || (vanilla.join(&child).is_dir() && (cfg!(not(unix)) || !filters.is_empty()))
             {
                 mirror(
@@ -528,6 +603,7 @@ fn build_overlay_uncached(
                     vanilla,
                     out,
                     touched,
+                    hidden,
                     files,
                     merged,
                     filters,
@@ -551,6 +627,7 @@ fn build_overlay_uncached(
         vanilla,
         out,
         &touched_dirs,
+        &hidden,
         &files,
         &merged,
         &filters,
@@ -741,7 +818,9 @@ impl SelectionModel {
     /// `available` in any order; `selected` as options.txt lists them,
     /// bottom first.
     pub fn new(mut available: Vec<Selectable>, selected: &[String]) -> Self {
-        // PackRepository.available is a TreeMap by id (String.compareTo).
+        // PackRepository.discoverAvailable: every source's packs go into one
+        // TreeMap by id (String.compareTo), so `file/` packs sort among the
+        // built-in ones.
         available.sort_by(|a, b| a.id.encode_utf16().cmp(b.id.encode_utf16()));
         available.dedup_by(|a, b| a.id == b.id);
         let mut m = Self {
@@ -939,7 +1018,8 @@ mod tests {
     }
     #[test]
     fn overlay_layers_packs_over_vanilla() {
-        let base = std::env::temp_dir().join(format!("horizon-packs-{}", std::process::id()));
+        // `&` would split an unquoted `cmd /C mklink` line.
+        let base = std::env::temp_dir().join(format!("horizon-packs-&{}", std::process::id()));
         let _ = fs::remove_dir_all(&base);
         let vanilla = base.join("vanilla");
         fs::create_dir_all(vanilla.join("assets/minecraft/textures/block")).unwrap();
@@ -960,6 +1040,13 @@ mod tests {
         )
         .unwrap();
         fs::write(vanilla.join("facts.json"), b"[]").unwrap();
+        // A directory no pack touches (#1688: a font json names sheets in it).
+        fs::create_dir_all(vanilla.join("assets/minecraft/textures/font")).unwrap();
+        fs::write(
+            vanilla.join("assets/minecraft/textures/font/ascii.png"),
+            b"font",
+        )
+        .unwrap();
         let pack_dir = base.join("packs/Mine");
         fs::create_dir_all(pack_dir.join("assets/minecraft/textures/block")).unwrap();
         fs::write(
@@ -997,6 +1084,17 @@ mod tests {
             br#"{"a":"vanilla","b":"pack"}"#
         );
         assert_eq!(fs::read(out.join("facts.json")).unwrap(), b"[]");
+        assert_eq!(
+            fs::read(out.join("assets/minecraft/textures/font/ascii.png")).unwrap(),
+            b"font"
+        );
+        // Linked, not mirrored: a junction on Windows, a symlink on unix.
+        assert!(
+            fs::symlink_metadata(out.join("assets/minecraft/textures/font"))
+                .unwrap()
+                .file_type()
+                .is_symlink()
+        );
         let _ = fs::remove_dir_all(base);
     }
     #[test]

crates/horizon-client-render/src/packs/cache.rs

@@ -8,8 +8,9 @@ use std::io::Read;
 use std::{collections::BTreeSet, fs, io, path::Path, path::PathBuf};
 
 // Bump when overlay/merge semantics change. Markers are disposable cache data.
+// Version 4 mirrored every untouched directory file by file on Windows.
 // Version 3 could omit untouched vanilla directories on Windows (#1649, #1688).
-const VERSION: u32 = 4;
+const VERSION: u32 = 5;
 
 #[derive(Default, Serialize, Deserialize)]
 pub(super) struct Dependencies {
@@ -348,6 +349,27 @@ mod tests {
             fs::create_dir_all(path.parent().unwrap()).unwrap();
             fs::write(path, bytes).unwrap();
         }
+        /// Waits for the filesystem's clock to move on, as it does between a build and a
+        /// person's next edit. On Unix the cache compares stamps (length, mtime, ctime, inode),
+        /// and Linux takes them from a coarse clock (a few milliseconds a tick): an edit in the
+        /// tick of the build before kept them all, and the tests failed at random.
+        fn next_tick(&self) {
+            let probe = self.0.with_extension("tick");
+            // New bytes each time: NTFS keeps the time of a write that changes nothing.
+            let stamp = |n: u32| {
+                fs::write(&probe, n.to_le_bytes()).unwrap();
+                fs::metadata(&probe).unwrap().modified().unwrap()
+            };
+            let start = stamp(0);
+            // A second at most: no clock is that coarse, and a test never hangs on one.
+            for n in 1..1000 {
+                std::thread::sleep(std::time::Duration::from_millis(1));
+                if stamp(n) != start {
+                    break;
+                }
+            }
+            let _ = fs::remove_file(&probe);
+        }
         fn dir_pack(&self, name: &str) -> Pack {
             self.write(
                 &format!("{name}/pack.mcmeta"),
@@ -370,6 +392,7 @@ mod tests {
                 output_signature(&cached).unwrap(),
                 output_signature(&self.0.join("reference")).unwrap()
             );
+            self.next_tick();
         }
     }
     impl Drop for Fixture {

crates/horizon-client-render/src/settings.rs

@@ -174,6 +174,12 @@ pub struct Settings {
     pub toggle_use: bool,
     /// Taps of the sprint key counted as double taps (sprintWindow).
     pub sprint_window: i32,
+    /// Show the operator items tab in a creative inventory.
+    pub operator_items_tab: bool,
+    /// Allow platform quit shortcuts to close the game window.
+    pub quit_shortcuts: bool,
+    /// On macOS, turn Control-click into a right click.
+    pub ctrl_click_emulates_right_click: bool,
     /// Horizon's own graphics settings (`horizon-graphics.txt`, not options.txt).
     pub horizon: crate::graphics::Graphics,
     /// Controller settings (`horizon-controller.txt`, Horizon's own).
@@ -256,6 +262,9 @@ impl Default for Settings {
             toggle_attack: false,
             toggle_use: false,
             sprint_window: 7,
+            operator_items_tab: false,
+            quit_shortcuts: true,
+            ctrl_click_emulates_right_click: false,
             horizon: Default::default(),
             controller: Default::default(),
             extras: Default::default(),
@@ -418,6 +427,9 @@ impl Settings {
             toggle_attack: f.bool("toggleAttack"),
             toggle_use: f.bool("toggleUse"),
             sprint_window: f.int("sprintWindow"),
+            operator_items_tab: f.bool("operatorItemsTab"),
+            quit_shortcuts: f.bool("quitShortcuts"),
+            ctrl_click_emulates_right_click: f.bool("ctrlClickEmulatesRightClick"),
             horizon: Default::default(),
             controller: Default::default(),
             extras: Default::default(),
@@ -518,6 +530,13 @@ impl Settings {
         put_b(&mut f, "toggleAttack", self.toggle_attack);
         put_b(&mut f, "toggleUse", self.toggle_use);
         put_i(&mut f, "sprintWindow", self.sprint_window);
+        put_b(&mut f, "operatorItemsTab", self.operator_items_tab);
+        put_b(&mut f, "quitShortcuts", self.quit_shortcuts);
+        put_b(
+            &mut f,
+            "ctrlClickEmulatesRightClick",
+            self.ctrl_click_emulates_right_click,
+        );
         put_b(&mut f, "autoJump", self.auto_jump);
         put_s(&mut f, "lang", &self.language);
         put_b(&mut f, "forceUnicodeFont", self.force_unicode);
@@ -664,7 +683,13 @@ pub enum Opt {
     MenuBlur,
     ToggleCrouch,
     ToggleSprint,
+    ToggleAttack,
+    ToggleUse,
     AutoJump,
+    SprintWindow,
+    QuitShortcuts,
+    CtrlClickEmulatesRightClick,
+    OperatorItemsTab,
     ChatVisibility,
     ChatColors,
     ChatLinks,

crates/horizon-client-render/src/sound_engine.rs

@@ -58,6 +58,8 @@ pub enum Ticking {
     Bee { bee: u32, aggressive: bool },
     /// `GuardianAttackSoundInstance`.
     GuardianAttack { guardian: u32 },
+    /// `ElytraOnPlayerSoundInstance`: ticks since it started.
+    Elytra { time: i32 },
 }
 /// What a minecart's sound instances read about it.
 #[derive(Clone, Copy, Debug)]
@@ -95,6 +97,12 @@ pub struct TickContext {
     pub mobs: Vec<MobSound>,
     /// `!tickRateManager().runsNormally()`.
     pub frozen: bool,
+    /// The player's position.
+    pub player_position: [f64; 3],
+    /// `getDeltaMovement().lengthSqr()` of the player.
+    pub player_speed_sqr: f64,
+    /// `isFallFlying()` of the player.
+    pub player_fall_flying: bool,
 }
 /// `AbstractSoundInstance` and its subclasses' fields.
 #[derive(Clone, Debug)]
@@ -390,6 +398,24 @@ impl SoundInstance {
         };
         s
     }
+    /// `new ElytraOnPlayerSoundInstance(player)`: looping at volume 0.1 until
+    /// its first tick.
+    pub fn elytra(position: [f64; 3], random: LegacyRandom) -> Self {
+        let mut s = Self::new(
+            "minecraft:item.elytra.flying",
+            PLAYERS,
+            0.1,
+            1.0,
+            random,
+            true,
+            0,
+            Attenuation::Linear,
+            position,
+            false,
+        );
+        s.ticking = Ticking::Elytra { time: 0 };
+        s
+    }
     pub fn tickable(&self) -> bool {
         self.ticking != Ticking::No
     }
@@ -494,6 +520,37 @@ impl SoundInstance {
                     self.volume = 0.0;
                 }
             }
+            Ticking::Elytra { time } => {
+                *time += 1;
+                let time = *time;
+                if ctx.player_removed || (time > 20 && !ctx.player_fall_flying) {
+                    self.stop();
+                    return;
+                }
+                let [x, y, z] = ctx.player_position;
+                self.position = [
+                    f64::from(x as f32),
+                    f64::from(y as f32),
+                    f64::from(z as f32),
+                ];
+                let speed = ctx.player_speed_sqr as f32;
+                self.volume = if speed >= 1.0e-7 {
+                    (speed / 4.0).clamp(0.0, 1.0)
+                } else {
+                    0.0
+                };
+                // Silent for a second, then a second's fade in.
+                if time < 20 {
+                    self.volume = 0.0;
+                } else if time < 40 {
+                    self.volume *= (time - 20) as f32 / 20.0;
+                }
+                self.pitch = if self.volume > 0.8 {
+                    1.0 + (self.volume - 0.8)
+                } else {
+                    1.0
+                };
+            }
             Ticking::GuardianAttack { guardian } => {
                 let id = *guardian;
                 // The client's guardian never has a target of its own, so

crates/horizon-client-render/src/split_layout.rs

@@ -0,0 +1,272 @@
+//! Splitscreen's layout, pure data tested without a window: where each player's view goes in
+//! its window (`place`).
+use winit::dpi::PhysicalSize;
+
+/// Players at most: P1 and fifteen more.
+pub const MAX_PLAYERS: usize = 16;
+
+/// A player's view: its window (an index into the windows), its corner there and its size.
+pub type View = (usize, [u32; 2], PhysicalSize<u32>);
+
+/// Rows of five to sixteen players sharing a window, widest first (columns on a tall window): every
+/// view stays near a screen's shape, where a full grid would leave a long thin one.
+const ROWS: [&[u32]; MAX_PLAYERS - 4] = [
+    &[3, 2],
+    &[3, 3],
+    &[3, 2, 2],
+    &[3, 3, 2],
+    &[3, 3, 3],
+    &[4, 3, 3],
+    &[4, 4, 3],
+    &[4, 4, 4],
+    &[4, 3, 3, 3],
+    &[4, 4, 3, 3],
+    &[4, 4, 4, 3],
+    &[4, 4, 4, 4],
+];
+
+/// `order` made a whole order of `n` players: those it names (once, if there are), then the
+/// others, P1 first.
+pub fn ordered(order: &[usize], n: usize) -> Vec<usize> {
+    let mut out: Vec<usize> = Vec::with_capacity(n);
+    for &i in order {
+        if i < n && !out.contains(&i) {
+            out.push(i);
+        }
+    }
+    out.extend((0..n).filter(|i| !order.contains(i)));
+    out
+}
+
+/// `place` with the players sharing a window in `order` (`ordered`): the first left or on top.
+/// The views are still by player.
+pub fn place_ordered(
+    windows: &[usize],
+    order: &[usize],
+    sizes: &[PhysicalSize<u32>],
+    two: u8,
+    three: u8,
+) -> Vec<View> {
+    let order = ordered(order, windows.len());
+    let in_order: Vec<usize> = order.iter().map(|&i| windows[i]).collect();
+    let placed = place(&in_order, sizes, two, three);
+    let mut views = placed.clone();
+    for (k, &i) in order.iter().enumerate() {
+        views[i] = placed[k];
+    }
+    views
+}
+
+/// Each player's view, given the window each is in and the windows' sizes. Players in one window
+/// share it in the order they come: two take halves (`two`: 0 side by side when wider than
+/// tall, 1 side by side, 2 top and bottom); three (`three`: 0 the first wide on top and two below,
+/// 1 the first tall on the left and two on the right, 2 three columns); four its quarters; five
+/// to sixteen in balanced rows (`ROWS`).
+pub fn place(windows: &[usize], sizes: &[PhysicalSize<u32>], two: u8, three: u8) -> Vec<View> {
+    windows
+        .iter()
+        .enumerate()
+        .map(|(i, &window)| {
+            let here = windows.iter().filter(|&&w| w == window).count();
+            let slot = windows[..i].iter().filter(|&&w| w == window).count() as u32;
+            let size = sizes
+                .get(window)
+                .copied()
+                .unwrap_or(PhysicalSize::new(1, 1));
+            let (w, h) = (size.width, size.height);
+            let side_by_side = match two {
+                1 => true,
+                2 => false,
+                _ => w >= h,
+            };
+            // The view's cell as fractions of the window: (x0, x1, y0, y1) in halves or thirds.
+            let cell = |x0: u32, x1: u32, y0: u32, y1: u32, of: u32| {
+                [w * x0 / of, w * x1 / of, h * y0 / of, h * y1 / of]
+            };
+            let [x0, x1, y0, y1] = match (here, slot) {
+                (1, _) => cell(0, 1, 0, 1, 1),
+                (2, s) if side_by_side => cell(s, s + 1, 0, 2, 2),
+                (2, s) => cell(0, 2, s, s + 1, 2),
+                (3, s) => match (three, s) {
+                    (2, s) => cell(s, s + 1, 0, 3, 3),
+                    (1, 0) => cell(0, 1, 0, 2, 2),
+                    (1, s) => cell(1, 2, s - 1, s, 2),
+                    (_, 0) => cell(0, 2, 0, 1, 2),
+                    (_, s) => cell(s - 1, s, 1, 2, 2),
+                },
+                (4, s) => cell(s % 2, s % 2 + 1, s / 2, s / 2 + 1, 2),
+                (n, s) => rows(n, s, w, h),
+            };
+            (
+                window,
+                [x0, y0],
+                PhysicalSize::new((x1 - x0).max(1), (y1 - y0).max(1)),
+            )
+        })
+        .collect()
+}
+
+/// Five to sixteen players: `slot`'s cell `[x0, x1, y0, y1]` in balanced rows (`ROWS`), or
+/// in columns when the window is taller than wide.
+fn rows(n: usize, slot: u32, w: u32, h: u32) -> [u32; 4] {
+    let counts = ROWS[n.clamp(5, MAX_PLAYERS) - 5];
+    let bands = counts.len() as u32;
+    let (mut band, mut k) = (0, slot);
+    while band + 1 < bands && k >= counts[band as usize] {
+        k -= counts[band as usize];
+        band += 1;
+    }
+    let across = counts[band as usize];
+    // Along: the long side, divided between a band's views; down: the bands.
+    let (along, down) = if w >= h { (w, h) } else { (h, w) };
+    let (a0, a1) = (along * k / across, along * (k + 1) / across);
+    let (d0, d1) = (down * band / bands, down * (band + 1) / bands);
+    if w >= h {
+        [a0, a1, d0, d1]
+    } else {
+        [d0, d1, a0, a1]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn size(w: u32, h: u32) -> PhysicalSize<u32> {
+        PhysicalSize::new(w, h)
+    }
+
+    #[test]
+    fn players_on_one_screen_share_it() {
+        let wide = [size(1920, 1080)];
+        assert_eq!(
+            place(&[0, 0], &wide, 0, 0)[1],
+            (0, [960, 0], size(960, 1080))
+        );
+        assert_eq!(
+            place(&[0, 0], &wide, 2, 0)[1],
+            (0, [0, 540], size(1920, 540))
+        );
+        // Auto on a tall screen: top and bottom.
+        assert_eq!(place(&[0, 0], &[size(1080, 1920)], 0, 0)[1].1, [0, 960]);
+        assert_eq!(
+            place(&[0; 4], &wide, 0, 0)[3],
+            (0, [960, 540], size(960, 540))
+        );
+    }
+
+    #[test]
+    fn desk_and_couch() {
+        // P1 alone at the desk; P2 and P3 share the TV.
+        let screens = [size(3024, 1964), size(3840, 2160)];
+        let views = place(&[0, 1, 1], &screens, 0, 0);
+        assert_eq!(views[0], (0, [0, 0], size(3024, 1964)));
+        assert_eq!(views[1], (1, [0, 0], size(1920, 2160)));
+        assert_eq!(views[2], (1, [1920, 0], size(1920, 2160)));
+    }
+
+    #[test]
+    fn three_on_a_screen() {
+        let tv = [size(1920, 1080)];
+        // One wide on top, two below.
+        let top = place(&[0; 3], &tv, 0, 0);
+        assert_eq!(top[0], (0, [0, 0], size(1920, 540)));
+        assert_eq!(top[2], (0, [960, 540], size(960, 540)));
+        // One tall on the left, two stacked on the right.
+        let left = place(&[0; 3], &tv, 0, 1);
+        assert_eq!(left[0], (0, [0, 0], size(960, 1080)));
+        assert_eq!(left[2], (0, [960, 540], size(960, 540)));
+        // Three columns.
+        assert_eq!(
+            place(&[0; 3], &tv, 0, 2)[2],
+            (0, [1280, 0], size(640, 1080))
+        );
+    }
+
+    #[test]
+    fn two_windows_two_players_each() {
+        // P1 and P2 at the desk, P3 and P4 on the TV: halves in each window.
+        let screens = [size(3024, 1964), size(3840, 2160)];
+        let views = place(&[0, 0, 1, 1], &screens, 0, 0);
+        assert_eq!(views[1], (0, [1512, 0], size(1512, 1964)));
+        assert_eq!(views[2], (1, [0, 0], size(1920, 2160)));
+        assert_eq!(views[3], (1, [1920, 0], size(1920, 2160)));
+    }
+
+    #[test]
+    fn five_to_eight_in_rows_of_three_and_two() {
+        let tv = [size(1920, 1080)];
+        let eight = place(&[0; 8], &tv, 0, 0);
+        assert_eq!(eight[0], (0, [0, 0], size(640, 360)));
+        assert_eq!(eight[5], (0, [1280, 360], size(640, 360)));
+        assert_eq!(eight[7], (0, [960, 720], size(960, 360)));
+        let seven = place(&[0; 7], &tv, 0, 0);
+        assert_eq!(seven[3], (0, [0, 360], size(960, 360)));
+        // Every count tiles the window exactly: no gap, no overlap.
+        for n in 5..=MAX_PLAYERS {
+            for screen in [size(1920, 1080), size(1080, 1920), size(1711, 997)] {
+                let views = place(&vec![0; n], &[screen], 0, 0);
+                for (i, (_, [x, y], size)) in views.iter().enumerate() {
+                    assert!(x + size.width <= screen.width && y + size.height <= screen.height);
+                    for (_, [ox, oy], other) in &views[..i] {
+                        assert!(
+                            x + size.width <= *ox
+                                || ox + other.width <= *x
+                                || y + size.height <= *oy
+                                || oy + other.height <= *y,
+                            "overlapping views for {n} in {screen:?}"
+                        );
+                    }
+                }
+                let area: u64 = views
+                    .iter()
+                    .map(|v| u64::from(v.2.width) * u64::from(v.2.height))
+                    .sum();
+                assert_eq!(
+                    area,
+                    u64::from(screen.width) * u64::from(screen.height),
+                    "{n} in {screen:?}"
+                );
+            }
+        }
+        // A tall window: columns.
+        let tall = place(&[0; 5], &[size(1080, 1920)], 0, 0);
+        assert_eq!(tall[0], (0, [0, 0], size(540, 640)));
+        assert_eq!(tall[4], (0, [540, 960], size(540, 960)));
+    }
+
+    #[test]
+    fn sixteen_players_form_a_four_by_four_grid() {
+        let views = place(&[0; 16], &[size(3840, 2160)], 0, 0);
+        for (i, view) in views.iter().enumerate() {
+            assert_eq!(
+                *view,
+                (
+                    0,
+                    [(i as u32 % 4) * 960, (i as u32 / 4) * 540],
+                    size(960, 540)
+                )
+            );
+        }
+    }
+
+    #[test]
+    fn an_order_names_each_player_once_and_the_others_come_last() {
+        assert_eq!(ordered(&[], 3), [0, 1, 2]);
+        assert_eq!(ordered(&[2, 0], 3), [2, 0, 1]);
+        // Gone players and repeats are dropped.
+        assert_eq!(ordered(&[5, 1, 1], 3), [1, 0, 2]);
+    }
+
+    #[test]
+    fn players_sharing_a_window_fill_it_in_their_order() {
+        let wide = [size(2000, 1000)];
+        // P2 first: P2 on the left, P1 on the right.
+        let views = place_ordered(&[0, 0], &[1, 0], &wide, 0, 0);
+        assert_eq!(views[1].1, [0, 0]);
+        assert_eq!(views[0].1, [1000, 0]);
+        // P3 first of three: the wide view on top is P3's.
+        let views = place_ordered(&[0, 0, 0], &[2], &wide, 0, 0);
+        assert_eq!(views[2].2, size(2000, 500));
+    }
+}

crates/horizon-client-render/src/streaming.rs

@@ -99,6 +99,9 @@ pub trait LodSampler: Send {
     fn drain_details(&mut self) -> Vec<LodDetail> {
         Vec::new()
     }
+    /// Reduced far detail (`graphics::FarDetail::Reduced`): `grid` may then
+    /// approximate wide cells.
+    fn set_approximate(&mut self, _approximate: bool) {}
     fn sample(&mut self, x: i32, z: i32) -> Option<crate::lod::Surface>;
     fn column(&mut self, x: i32, z: i32) -> crate::lod::Column {
         crate::lod::Column::from_surface(self.sample(x, z))
@@ -168,6 +171,9 @@ enum Job {
     /// Proto chunks checked out to be saved (`ChunkGenerator::save_protos`),
     /// off the main thread like vanilla's IOWorker.
     Save(Vec<((i32, i32), Proto)>),
+    /// Meshes the renderer is done with (`Streaming::free`): their memory
+    /// is given back here, not in the frame.
+    Free(Vec<((i32, i32, i32), SectionMesh)>),
 }
 pub enum Done {
     Generated(Chunk),
@@ -398,8 +404,14 @@ impl GenerationScan {
                     wanted.push((input.ranges.priority(x, z, input.loading), x, z));
                 }
             }
-            // Forced chunks and their generation neighbourhood.
-            let reach = margin - 1;
+            // Forced chunks and their generation neighbourhood: the ring that
+            // is decorated (or finished, without decoration) and the one its
+            // 3x3 needs.
+            let reach = if input.decorates {
+                FORCED_TERRAIN_RING
+            } else {
+                FORCED_FEATURES_RING
+            };
             for &(fx, fz) in input.ranges.forced {
                 for dz in -reach..=reach {
                     for dx in -reach..=reach {
@@ -510,6 +522,10 @@ impl Streaming {
                                     generator.save_protos(&refs);
                                     Done::Saved(protos)
                                 }
+                                Job::Free(meshes) => {
+                                    drop(meshes);
+                                    continue;
+                                }
                                 Job::Light(x, z, region, seq, sky) => {
                                     Done::Lit(x, z, light_chunk(&borrow(&region), &light, sky), seq)
                                 }
@@ -660,6 +676,17 @@ impl Streaming {
             }
         }
     }
+    /// Give back meshes the renderer has copied: a worker frees them, ahead of
+    /// other jobs, as vanilla's compile task closes its mesh data on its own
+    /// thread once copied (`SectionRenderDispatcher.RenderSection.CompileTask.doTask`).
+    /// Freed in the frame, the hundreds of meshes a chunk border brings waited
+    /// on the allocator behind every busy worker: up to 20 ms of a frame each
+    /// time while flying at render distance 32.
+    pub fn free(&mut self, meshes: Vec<((i32, i32, i32), SectionMesh)>) {
+        if !meshes.is_empty() {
+            self.submit(None, 0, Job::Free(meshes));
+        }
+    }
     /// A column the server unloaded (ClientboundForgetLevelChunkPacket).
     pub fn forget(&mut self, world: &mut World, x: i32, z: i32) -> Option<Arc<Chunk>> {
         self.lit.remove(&(x, z));
@@ -676,7 +703,7 @@ impl Streaming {
     }
     /// Queue a job for the column `at`, nearest first: its distance (`distance`)
     /// times four plus `bias`, which orders a column's jobs. A job without a
-    /// column (a save) goes ahead of every other.
+    /// column (a save, meshes to free) goes ahead of every other.
     fn submit(&mut self, at: Option<(i32, i32)>, bias: i64, job: Job) {
         self.order += 1;
         let priority = at.map_or(i64::MIN, |(x, z)| self.distance(x, z) * 4 + bias);
@@ -910,6 +937,8 @@ impl Streaming {
         self.relight_edits(world);
         let deferred = std::mem::take(&mut self.deferred);
         let received = std::iter::from_fn(|| self.results.try_recv().ok());
+        // Meshes made stale meanwhile, freed with the uploaded ones (`free`).
+        let mut stale = Vec::new();
         for done in deferred.into_iter().chain(received.collect::<Vec<_>>()) {
             match done {
                 Done::Proto(x, z, proto, decorated) => {
@@ -966,12 +995,14 @@ impl Streaming {
                 }
                 Done::Meshed(x, sy, z, mesh, seq) => {
                     if self.meshing.get(&(x, sy, z)) != Some(&seq) {
+                        stale.push(((x, sy, z), mesh));
                         continue;
                     }
                     // Its column unloaded while it was meshed: nothing would
                     // ever remove the uploaded section.
                     if !world.chunks.contains_key(&(x, z)) {
                         self.meshing.remove(&(x, sy, z));
+                        stale.push(((x, sy, z), mesh));
                         continue;
                     }
                     self.meshing.remove(&(x, sy, z));
@@ -980,6 +1011,7 @@ impl Streaming {
                 }
             }
         }
+        self.free(stale);
         let mut removed = Vec::new();
         if sweep {
             // Unload far columns.
@@ -1021,10 +1053,10 @@ impl Streaming {
                         && i64::from(x - center.0).pow(2) + i64::from(z - center.1).pow(2) > r4 * r4
                         && !ranges.in_extra(x, z, 4)
                         && !ranges.in_band(x, z, 4)
-                        && !ranges
-                            .forced
-                            .iter()
-                            .any(|f| (x - f.0).abs() <= 3 && (z - f.1).abs() <= 3)
+                        && !ranges.forced.iter().any(|f| {
+                            (x - f.0).abs() <= FORCED_TERRAIN_RING
+                                && (z - f.1).abs() <= FORCED_TERRAIN_RING
+                        })
                 })
                 .map(|(k, _)| *k)
                 .collect();
@@ -1544,6 +1576,14 @@ pub fn in_view_distance(center: (i32, i32), radius: i32, x: i32, z: i32) -> bool
     let (dx, dz) = (gap(x - center.0), gap(z - center.1));
     dx * dx + dz * dz < i64::from(radius) * i64::from(radius)
 }
+/// The rings around a `/forceload`ed chunk, in chunks. Vanilla's FORCED
+/// ticket is level 31 (`ChunkMap.FORCED_TICKET_LEVEL`), the level rises one
+/// per ring (`ChunkTracker.computeLevelFromNeighbor`), and the level picks
+/// the column's status (`ChunkLevel.generationStatus`): full (33) two rings
+/// out, features (34) at three, terrain (35) at four.
+const FORCED_FULL_RING: i32 = 2;
+const FORCED_FEATURES_RING: i32 = 3;
+const FORCED_TERRAIN_RING: i32 = 4;
 /// The areas kept loaded: circles around the player and `extra`, and forced chunks.
 struct Ranges<'a> {
     center: (i32, i32),
@@ -1799,7 +1839,16 @@ impl Ranges<'_> {
         if dx * dx + dz * dz <= r * r {
             return true;
         }
-        let reach = (margin - 1).max(0);
+        // A forced chunk holds a FORCED ticket at level 31
+        // (`ChunkMap.FORCED_TICKET_LEVEL`), and the level rises one per ring
+        // (`ChunkTracker.computeLevelFromNeighbor`): the margin is the
+        // vanilla status ring the caller asks for.
+        let reach = match margin {
+            1 => FORCED_FULL_RING,
+            2 => FORCED_FEATURES_RING,
+            3 => FORCED_TERRAIN_RING,
+            _ => margin + 1,
+        };
         self.forced
             .iter()
             .any(|f| (x - f.0).abs() <= reach && (z - f.1).abs() <= reach)
@@ -2037,9 +2086,14 @@ mod tests {
                 }
             }
         }
+        let forced_reach = if input.decorates {
+            FORCED_TERRAIN_RING
+        } else {
+            FORCED_FEATURES_RING
+        };
         for &(fx, fz) in input.ranges.forced {
-            for dz in -(margin - 1)..=(margin - 1) {
-                for dx in -(margin - 1)..=(margin - 1) {
+            for dz in -forced_reach..=forced_reach {
+                for dx in -forced_reach..=forced_reach {
                     let (x, z) = (fx + dx, fz + dz);
                     if missing(x, z) {
                         wanted.push((input.ranges.distance(x, z), x, z));
@@ -2441,6 +2495,57 @@ mod tests {
             }
         }
     }
+
+    /// A `/forceload`ed chunk holds a FORCED ticket at level 31
+    /// (`ChunkMap.FORCED_TICKET_LEVEL`): the level rises one per ring
+    /// (`ChunkTracker.computeLevelFromNeighbor`) and picks the column's
+    /// status (`ChunkLevel.generationStatus`). So vanilla finishes the two
+    /// rings around it (33), gives the third its features (34) and the
+    /// fourth its terrain (35), and the rings past that are left alone.
+    #[test]
+    fn forced_chunks_reach_vanillas_rings() {
+        let forced: HashSet<(i32, i32)> = [(40, -40)].into();
+        let r = Ranges {
+            // The player's own area, far away.
+            center: (-400, 300),
+            radius: 2,
+            extra: &[],
+            forced: &forced,
+            cover: None,
+            band: None,
+        };
+        let level = |x: i32, z: i32| 31 + (x - 40).abs().max((z + 40).abs());
+        for x in 40 - 6..=40 + 6 {
+            for z in -40 - 6..=-40 + 6 {
+                // The full ring: the column becomes a level chunk.
+                assert_eq!(r.in_range(x, z, 1), level(x, z) <= 33, "({x}, {z})");
+                // The features ring, and the terrain ring.
+                assert_eq!(r.in_range(x, z, 2), level(x, z) <= 34, "({x}, {z})");
+                assert_eq!(r.in_range(x, z, 3), level(x, z) <= 35, "({x}, {z})");
+                assert_eq!(r.requested(x, z, true), level(x, z) <= 35, "({x}, {z})");
+                assert_eq!(r.chunk_kept(x, z, true), level(x, z) <= 35, "({x}, {z})");
+                assert_eq!(r.unloaded(x, z, true), level(x, z) > 35, "({x}, {z})");
+            }
+        }
+        // Generation reaches the terrain ring: the features ring is
+        // decorated from it.
+        let mut fixture = GenerationFixture::new(2, true);
+        fixture.center = (-400, 300);
+        fixture.forced = forced;
+        let candidates = GenerationScan::default()
+            .candidates(fixture.input(), usize::MAX)
+            .expect("a scan");
+        for (dx, dz) in [(-4, 0), (4, 0), (0, -4), (0, 4), (3, 3)] {
+            assert!(
+                candidates
+                    .iter()
+                    .any(|&(_, x, z)| (x, z) == (40 + dx, -40 + dz)),
+                "the terrain ring at ({}, {}) is not generated",
+                40 + dx,
+                -40 + dz
+            );
+        }
+    }
 }
 
 #[cfg(test)]

crates/horizon-client-render/src/world.rs

@@ -1,12 +1,10 @@
 //! Resident client world: streamed chunk columns plus the bookkeeping the game
 //! loop needs to relight and remesh after edits.
 use crate::chunk::{Chunk, MIN_Y, SECTIONS};
+use crate::fast_hash::{FxHashMap, FxHashSet};
 use horizon_core::random::LegacyRandom;
 use horizon_world::registry::BlockStateId;
-use std::{
-    collections::{HashMap, HashSet},
-    sync::Arc,
-};
+use std::sync::Arc;
 
 /// Sections (x, section index, z) waiting to be remeshed, kept by column
 /// (a bit per section index), so the mesh scheduler looks at each column once
@@ -65,14 +63,14 @@ pub struct World {
     /// Saved entities of chunks that just loaded, spawned by the game.
     pub loaded_entities: Vec<((i32, i32), Vec<horizon_world::nbt::Tag>)>,
     /// Chunks changed since the last save.
-    pub modified: HashSet<(i32, i32)>,
+    pub modified: FxHashSet<(i32, i32)>,
     /// Block entities, and the order they tick in.
     pub block_entities: crate::block_entities::BlockEntities,
     /// Each chest's `ContainerOpenersCounter`: opener count and largest
     /// interaction range.
-    pub chest_openers: HashMap<(i32, i32, i32), (i32, f64)>,
+    pub chest_openers: FxHashMap<(i32, i32, i32), (i32, f64)>,
     /// `BaseContainerBlockEntity.name`: custom names of container block entities.
-    pub block_names: HashMap<(i32, i32, i32), String>,
+    pub block_names: FxHashMap<(i32, i32, i32), String>,
     /// States (by id) whose writes are recorded in `watched_writes` (sculk
     /// blocks, which need a block entity).
     pub watched: Vec<bool>,
@@ -80,7 +78,7 @@ pub struct World {
     pub watched_writes: Vec<((i32, i32, i32), u32, u32)>,
     /// `ChunkAccess.inhabitedTime` of resident chunks: ticks a player spent
     /// within spawning range (local difficulty).
-    pub inhabited: HashMap<(i32, i32), i64>,
+    pub inhabited: FxHashMap<(i32, i32), i64>,
     pub game_time: i64,
     pub day_time: i64,
     pub weather: Weather,
@@ -177,13 +175,13 @@ impl World {
             dirty_light: Default::default(),
             light_edits: Vec::new(),
             loaded_entities: Vec::new(),
-            modified: HashSet::new(),
+            modified: FxHashSet::default(),
             block_entities: Default::default(),
-            chest_openers: HashMap::new(),
-            block_names: HashMap::new(),
+            chest_openers: FxHashMap::default(),
+            block_names: FxHashMap::default(),
             watched: Vec::new(),
             watched_writes: Vec::new(),
-            inhabited: HashMap::new(),
+            inhabited: FxHashMap::default(),
             game_time: 0,
             day_time: 1000,
             weather: Weather::default(),
@@ -274,20 +272,40 @@ impl World {
                 log.push((x, y, z));
             }
             self.modified.insert((x >> 4, z >> 4));
+            // The mesher reads a 3x3x3 neighbourhood for AO, so a write marks
+            // the sections it can reach: this section, the one above/below
+            // only on a section face, and a neighbour column only on a chunk
+            // border (the diagonal only where both borders meet).
             let sy = (y - MIN_Y) >> 4;
-            for dz in -1..=1 {
-                for dy in -1..=1 {
-                    for dx in -1..=1 {
-                        let (bx, by, bz) = (x + dx, y + dy, z + dz);
-                        let s = (by - MIN_Y) >> 4;
-                        if !(0..SECTIONS as i32).contains(&s) {
-                            continue;
-                        }
-                        self.dirty_sections.insert((bx >> 4, s, bz >> 4));
-                    }
+            let local_y = y & 15;
+            let mark = |dirty: &mut DirtySections, bx: i32, bz: i32| {
+                dirty.insert((bx >> 4, sy, bz >> 4));
+                if local_y == 0 && sy > 0 {
+                    dirty.insert((bx >> 4, sy - 1, bz >> 4));
                 }
+                if local_y == 15 && sy + 1 < SECTIONS as i32 {
+                    dirty.insert((bx >> 4, sy + 1, bz >> 4));
+                }
+            };
+            let (bx, bz) = (x & 15, z & 15);
+            mark(&mut self.dirty_sections, x, z);
+            if bx == 0 {
+                mark(&mut self.dirty_sections, x - 1, z);
+            } else if bx == 15 {
+                mark(&mut self.dirty_sections, x + 1, z);
+            }
+            if bz == 0 {
+                mark(&mut self.dirty_sections, x, z - 1);
+            } else if bz == 15 {
+                mark(&mut self.dirty_sections, x, z + 1);
+            }
+            if (bx == 0 || bx == 15) && (bz == 0 || bz == 15) {
+                mark(
+                    &mut self.dirty_sections,
+                    if bx == 0 { x - 1 } else { x + 1 },
+                    if bz == 0 { z - 1 } else { z + 1 },
+                );
             }
-            let _ = sy;
             if self.chunks.get(&(x >> 4, z >> 4)).is_some_and(|c| c.lit) {
                 self.light_edits.push(((x, y, z), previous, state.0));
             } else {
@@ -407,11 +425,59 @@ impl Default for HealthRules {
 
 #[cfg(test)]
 mod tests {
-    use super::World;
-    use crate::chunk::Chunk;
+    use super::{DirtySections, World};
+    use crate::chunk::{Chunk, MIN_Y, SECTIONS};
     use horizon_world::registry::BlockStateId;
     use std::sync::Arc;
 
+    /// Every block write marks the same section set the 27-cell loop did, but
+    /// only the distinct keys: one in the interior, a neighbour section on a
+    /// section face, a neighbour column on a chunk border and the diagonal at
+    /// a corner (eight keys at a corner on a section face).
+    #[test]
+    fn writes_mark_exactly_the_reachable_sections() {
+        let mut world = World::new(BlockStateId(0), 0);
+        world.chunks.insert((0, 0), Arc::new(Chunk::empty(0, 0)));
+        for (x, y, z) in [
+            (3, 70, 3),
+            (0, 70, 3),
+            (15, 70, 3),
+            (3, 70, 0),
+            (0, 70, 0),
+            (15, 70, 15),
+            (0, MIN_Y, 0),
+            (0, 80, 0),
+            (15, MIN_Y + SECTIONS as i32 * 16 - 1, 15),
+        ] {
+            world.dirty_sections.clear();
+            world.set(x, y, z, BlockStateId(1)).unwrap();
+            let mut expected = DirtySections::default();
+            for dz in -1..=1 {
+                for dy in -1..=1 {
+                    for dx in -1..=1 {
+                        let (bx, by, bz) = (x + dx, y + dy, z + dz);
+                        let s = (by - MIN_Y) >> 4;
+                        if (0..SECTIONS as i32).contains(&s) {
+                            expected.insert((bx >> 4, s, bz >> 4));
+                        }
+                    }
+                }
+            }
+            let mut got: Vec<_> = world.dirty_sections.columns().collect();
+            let mut want: Vec<_> = expected.columns().collect();
+            got.sort_unstable();
+            want.sort_unstable();
+            assert_eq!(got, want, "write at {x} {y} {z}");
+            if (x & 15, z & 15) == (3, 3) {
+                assert_eq!(world.dirty_sections.len(), 1);
+            }
+            if (x & 15, z & 15, y & 15) == (0, 0, 0) && y > MIN_Y {
+                // Four columns, each with the section below and this one.
+                assert_eq!(world.dirty_sections.len(), 8);
+            }
+        }
+    }
+
     /// A box misses a state only where no section it reaches lists it, and
     /// unloaded columns or heights past the world count as their air.
     #[test]

crates/horizon-client-render/src/zip.rs

@@ -14,11 +14,13 @@ use zip::{CompressionMethod, ZipArchive};
 /// bomb stops here.
 const MAX_ENTRY: usize = 1 << 30;
 
-/// One archive with its entries indexed by name (`\` read as `/`, folders
-/// left out).
+/// One archive with its entries indexed by name (`\` read as `/`), files
+/// and folders apart.
 pub struct Zip {
     archive: ZipArchive<Cursor<Arc<[u8]>>>,
     entries: BTreeMap<String, usize>,
+    /// Folder entries (`name/`) by their name without the slash.
+    folders: BTreeMap<String, usize>,
     /// The archive's length: no size an entry claims can be bigger.
     len: usize,
 }
@@ -33,26 +35,44 @@ impl Zip {
         normalize_end(&mut data);
         let len = data.len();
         let archive = ZipArchive::new(Cursor::new(Arc::from(data))).map_err(invalid)?;
-        let entries = (0..archive.len())
-            .filter_map(|i| Some((archive.name_for_index(i)?.replace('\\', "/"), i)))
-            .filter(|(name, _)| !name.ends_with('/'))
-            .collect();
+        let (mut entries, mut folders) = (BTreeMap::new(), BTreeMap::new());
+        for i in 0..archive.len() {
+            let Some(name) = archive.name_for_index(i) else {
+                continue;
+            };
+            let name = name.replace('\\', "/");
+            match name.strip_suffix('/') {
+                Some(folder) => folders.insert(folder.to_owned(), i),
+                None => entries.insert(name, i),
+            };
+        }
         Ok(Self {
             archive,
             entries,
+            folders,
             len,
         })
     }
+    /// The files, as `FilePackResources.listResources` lists them (folder
+    /// entries skipped).
     pub fn names(&self) -> impl Iterator<Item = &str> {
         self.entries.keys().map(String::as_str)
     }
+    /// `FilePackResources.getResource` through `ZipFile.getEntry`: the file
+    /// `name`, else the folder entry `name/`, whose bytes Java reads like a
+    /// file's (Loka's pack stores its `pack.mcmeta` and `pack.png` that way).
+    fn index(&self, name: &str) -> Option<usize> {
+        self.entries
+            .get(name)
+            .or_else(|| self.folders.get(name))
+            .copied()
+    }
     pub fn contains(&self, name: &str) -> bool {
-        self.entries.contains_key(name)
+        self.index(name).is_some()
     }
     pub fn read(&self, name: &str) -> io::Result<Vec<u8>> {
-        let &index = self
-            .entries
-            .get(name)
+        let index = self
+            .index(name)
             .ok_or_else(|| io::Error::new(io::ErrorKind::NotFound, name.to_owned()))?;
         // A clone shares the bytes and the central directory: reading needs `&mut`.
         let mut archive = self.archive.clone();
@@ -133,13 +153,16 @@ mod tests {
     use super::*;
     /// A hand-built archive with one stored and one deflated entry.
     fn archive() -> Vec<u8> {
-        let files: [(&str, &[u8], bool); 2] = [
+        archive_of(&[
             ("pack.mcmeta", b"{\"pack\":{}}", false),
             ("a/b.txt", b"hello hello hello hello", true),
-        ];
+        ])
+    }
+    /// A hand-built archive of `(name, body, deflated)` entries.
+    fn archive_of(files: &[(&str, &[u8], bool)]) -> Vec<u8> {
         let mut out = Vec::new();
         let mut central = Vec::new();
-        for (name, body, deflate) in files {
+        for &(name, body, deflate) in files {
             let data = if deflate {
                 miniz_oxide::deflate::compress_to_vec(body, 6)
             } else {
@@ -174,8 +197,8 @@ mod tests {
         out.extend(&central);
         out.extend(0x0605_4b50u32.to_le_bytes());
         out.extend([0; 4]);
-        out.extend(2u16.to_le_bytes());
-        out.extend(2u16.to_le_bytes());
+        out.extend((files.len() as u16).to_le_bytes());
+        out.extend((files.len() as u16).to_le_bytes());
         out.extend((central.len() as u32).to_le_bytes());
         out.extend(start.to_le_bytes());
         out.extend([0; 2]);
@@ -191,6 +214,29 @@ mod tests {
         assert!(zip.read("missing").is_err());
     }
 
+    /// Loka's server pack (#3413) names its metadata `pack.mcmeta/`.
+    /// `ZipFile.getEntry("pack.mcmeta")` falls back to that folder entry and
+    /// vanilla reads its bytes; a file of the exact name still comes first.
+    #[test]
+    fn a_name_falls_back_to_its_folder_entry() {
+        let zip = Zip::from_bytes(archive_of(&[
+            ("pack.mcmeta/", b"{\"pack\":{\"pack_format\":75}}", true),
+            ("pack.png/", b"png", false),
+            ("a/", b"folder", false),
+            ("a", b"file", false),
+        ]))
+        .unwrap();
+        assert_eq!(zip.names().collect::<Vec<_>>(), ["a"]);
+        assert!(zip.contains("pack.mcmeta"));
+        assert_eq!(
+            zip.read("pack.mcmeta").unwrap(),
+            b"{\"pack\":{\"pack_format\":75}}"
+        );
+        assert_eq!(zip.read("pack.png").unwrap(), b"png");
+        assert_eq!(zip.read("a").unwrap(), b"file");
+        assert!(!zip.contains("pack"));
+    }
+
     /// A pack as zip tools write it: folder entries, a nested pack root,
     /// stored and deflated files, and a Windows-style name.
     fn written() -> Vec<u8> {

crates/horizon-client/assets/horizon/lang/en_us.json

@@ -11,5 +11,57 @@
   "horizon.options.look_deadzone": "Look Deadzone",
   "horizon.options.button_glyphs": "Button Glyphs",
   "horizon.options.menu_navigation": "Menu Navigation",
-  "horizon.options.on_screen_keyboard": "On-Screen Keyboard"
+  "horizon.options.on_screen_keyboard": "On-Screen Keyboard",
+  "horizon.options.chat_delay": "Chat Delay",
+  "horizon.options.lightbar.health": "Health",
+  "horizon.options.lightbar.dimension": "Dimension",
+  "horizon.options.glyphs.auto": "Auto",
+  "horizon.options.glyphs.xbox": "Xbox",
+  "horizon.options.glyphs.playstation": "PlayStation",
+  "horizon.options.glyphs.nintendo": "Nintendo",
+  "horizon.options.menu_focus": "Focus",
+  "horizon.options.menu_pointer": "Pointer",
+  "horizon.options.keyboard.auto": "Auto",
+  "horizon.options.keyboard.horizon": "Horizon",
+  "horizon.options.keyboard.steam": "Steam",
+  "horizon.options.unavailable": "This feature is not yet available in Horizon.",
+  "horizon.options.search": "Search settings...",
+  "horizon.pages.mods": "Mods",
+  "horizon.pages.shader_packs": "Shader Packs",
+  "horizon.pages.controller": "Controller Settings",
+  "horizon.pages.controller_binds": "Controller Binds",
+  "horizon.pages.extras": "Horizon Extras",
+  "horizon.pages.settings": "Horizon Settings",
+  "horizon.pages.agent": "AI Agent",
+  "horizon.pages.settings.tooltip": "Horizon's own settings: graphics, controllers, extras and mods.",
+  "horizon.pages.graphics.tooltip": "Graphics, simply: each setting says what it costs.",
+  "horizon.pages.graphics_advanced.tooltip": "Every graphics setting, Horizon's included, with what each costs.",
+  "horizon.pages.controller.tooltip": "Controllers: their buttons, sticks, vibration and menu navigation.",
+  "horizon.pages.extras.tooltip": "Optional additions, all off by default: the game stays vanilla until you turn one on.",
+  "horizon.pages.agent.tooltip": "Let your own AI agent play: horizon-ctl and MCP clients on this computer.",
+  "horizon.pages.shader_packs.tooltip": "Shader packs from the shaderpacks folder: Horizon's own and those in the shaders/ format. One runs at a time.",
+  "horizon.pages.mods.tooltip": "Mods made for Horizon, from the horizon-mods folder. Each runs in a sandbox and stays off until you turn it on.",
+  "horizon.pages.open.graphics": "Graphics...",
+  "horizon.pages.open.graphics_advanced": "Advanced Graphics...",
+  "horizon.pages.open.shader_packs": "Shader Packs...",
+  "horizon.pages.open.controller": "Controller Settings...",
+  "horizon.pages.open.extras": "Extras...",
+  "horizon.pages.open.mods": "Mods...",
+  "horizon.pages.open.agent": "AI Agent...",
+  "horizon.pages.open.horizon_graphics": "Horizon Graphics...",
+  "horizon.pages.open.controller_binds": "Controller Binds...",
+  "horizon.pages.open.horizon_settings": "Horizon Settings...",
+  "horizon.mods.empty": "No mods: put .hmod files in the horizon-mods folder",
+  "horizon.mods.stopped": " (Stopped)",
+  "horizon.mods.dev": " (Dev)",
+  "horizon.mods.settings": "Settings",
+  "horizon.mods.open_folder": "Open Mod Folder",
+  "horizon.shader_packs.empty": "No shader packs: put them in the shaderpacks folder",
+  "horizon.shader_packs.kind_horizon": " (Horizon)",
+  "horizon.agent.copy_details": "Copy Connection Details",
+  "horizon.multiplayer.join": "Join",
+  "horizon.multiplayer.cancel_reconnecting": "Cancel Reconnecting",
+  "horizon.multiplayer.join_friend": "Join a Friend",
+  "horizon.multiplayer.invite_code": "Invite Code",
+  "horizon.multiplayer.relay": "Relay (optional)"
 }

crates/horizon-client/assets/horizon/lang/ru_ru.json

@@ -11,5 +11,57 @@
   "horizon.options.look_deadzone": "Мёртвая зона обзора",
   "horizon.options.button_glyphs": "Символы кнопок",
   "horizon.options.menu_navigation": "Навигация по меню",
-  "horizon.options.on_screen_keyboard": "Экранная клавиатура"
+  "horizon.options.on_screen_keyboard": "Экранная клавиатура",
+  "horizon.options.chat_delay": "Задержка чата",
+  "horizon.options.lightbar.health": "Здоровье",
+  "horizon.options.lightbar.dimension": "Измерение",
+  "horizon.options.glyphs.auto": "Авто",
+  "horizon.options.glyphs.xbox": "Xbox",
+  "horizon.options.glyphs.playstation": "PlayStation",
+  "horizon.options.glyphs.nintendo": "Nintendo",
+  "horizon.options.menu_focus": "Фокус",
+  "horizon.options.menu_pointer": "Указатель",
+  "horizon.options.keyboard.auto": "Авто",
+  "horizon.options.keyboard.horizon": "Horizon",
+  "horizon.options.keyboard.steam": "Steam",
+  "horizon.options.unavailable": "Эта возможность в Horizon пока недоступна.",
+  "horizon.options.search": "Поиск настроек...",
+  "horizon.pages.mods": "Моды",
+  "horizon.pages.shader_packs": "Шейдерпаки",
+  "horizon.pages.controller": "Настройки контроллера",
+  "horizon.pages.controller_binds": "Назначения кнопок контроллера",
+  "horizon.pages.extras": "Дополнения Horizon",
+  "horizon.pages.settings": "Настройки Horizon",
+  "horizon.pages.agent": "ИИ-агент",
+  "horizon.pages.settings.tooltip": "Собственные настройки Horizon: графика, контроллеры, дополнения и моды.",
+  "horizon.pages.graphics.tooltip": "Графика без лишнего: у каждой настройки написано, чего она стоит.",
+  "horizon.pages.graphics_advanced.tooltip": "Все графические настройки, включая собственные настройки Horizon, и их цена.",
+  "horizon.pages.controller.tooltip": "Контроллеры: кнопки, стики, вибрация и навигация по меню.",
+  "horizon.pages.extras.tooltip": "Дополнительные возможности, все выключены по умолчанию: игра остаётся ванильной, пока вы не включите что-то.",
+  "horizon.pages.agent.tooltip": "Пусть играет ваш ИИ-агент: horizon-ctl и MCP-клиенты на этом компьютере.",
+  "horizon.pages.shader_packs.tooltip": "Шейдерпаки из папки shaderpacks: собственные паки Horizon и паки в формате shaders/. Одновременно работает один.",
+  "horizon.pages.mods.tooltip": "Моды для Horizon из папки horizon-mods. Каждый работает в песочнице и выключен, пока вы его не включите.",
+  "horizon.pages.open.graphics": "Графика...",
+  "horizon.pages.open.graphics_advanced": "Продвинутая графика...",
+  "horizon.pages.open.shader_packs": "Шейдерпаки...",
+  "horizon.pages.open.controller": "Настройки контроллера...",
+  "horizon.pages.open.extras": "Дополнения...",
+  "horizon.pages.open.mods": "Моды...",
+  "horizon.pages.open.agent": "ИИ-агент...",
+  "horizon.pages.open.horizon_graphics": "Графика Horizon...",
+  "horizon.pages.open.controller_binds": "Назначения кнопок...",
+  "horizon.pages.open.horizon_settings": "Настройки Horizon...",
+  "horizon.mods.empty": "Модов нет: положите файлы .hmod в папку horizon-mods",
+  "horizon.mods.stopped": " (остановлен)",
+  "horizon.mods.dev": " (разработка)",
+  "horizon.mods.settings": "Настройки",
+  "horizon.mods.open_folder": "Открыть папку модов",
+  "horizon.shader_packs.empty": "Шейдерпаков нет: положите их в папку shaderpacks",
+  "horizon.shader_packs.kind_horizon": " (Horizon)",
+  "horizon.agent.copy_details": "Скопировать данные подключения",
+  "horizon.multiplayer.join": "Подключиться",
+  "horizon.multiplayer.cancel_reconnecting": "Отменить переподключение",
+  "horizon.multiplayer.join_friend": "Играть с другом",
+  "horizon.multiplayer.invite_code": "Код приглашения",
+  "horizon.multiplayer.relay": "Ретранслятор (необязательно)"
 }

crates/horizon-client/assets/horizon/lang/uk_ua.json

@@ -0,0 +1,15 @@
+{
+  "horizon.options.controller": "Геймпад",
+  "horizon.options.vibration": "Вібрація",
+  "horizon.options.adaptive_triggers": "Адаптивні тригери",
+  "horizon.options.lightbar": "Світлова панель",
+  "horizon.options.look_sensitivity": "Чутливість огляду",
+  "horizon.options.invert_x": "Інвертувати огляд по X",
+  "horizon.options.invert_y": "Інвертувати огляд по Y",
+  "horizon.options.sneak_button": "Кнопка присідання",
+  "horizon.options.move_deadzone": "Мертва зона руху",
+  "horizon.options.look_deadzone": "Мертва зона огляду",
+  "horizon.options.button_glyphs": "Значки кнопок",
+  "horizon.options.menu_navigation": "Навігація в меню",
+  "horizon.options.on_screen_keyboard": "Екранна клавіатура"
+}

crates/horizon-client/examples/probe/chat_screen_fixture/registries.rs

@@ -43,6 +43,7 @@ pub fn registries(r: &Value, permission: u8) -> Registries {
     reg.timelines = strings(&r["timelines"]);
     reg.dimensions = strings(&r["dimensions"]);
     reg.players = strings(&r["players"]);
+    reg.selected_entities = strings(&r["selected_entities"]);
     reg.teams = strings(&r["teams"]);
     reg.objectives = strings(&r["objectives"]);
     reg.tracked = strings(&r["tracked"]);

crates/horizon-client/examples/probe/command_parse_fixture.rs

@@ -178,6 +178,7 @@ pub fn main() -> horizon_client::Result<()> {
     reg.timelines = strings(&r["timelines"]);
     reg.dimensions = strings(&r["dimensions"]);
     reg.players = strings(&r["players"]);
+    reg.selected_entities = strings(&r["selected_entities"]);
     reg.teams = strings(&r["teams"]);
     reg.objectives = strings(&r["objectives"]);
     reg.tracked = strings(&r["tracked"]);

crates/horizon-client/examples/probe/entity_anim_fixture.rs

@@ -150,7 +150,7 @@ fn entity_state(mob: &mut Mob, species: Species, case: &Value) {
             mob.extra.crouching = flag("isCrouching");
             mob.extra.passenger = flag("isPassenger");
             if flag("isHoldingBow") {
-                mob.extra.main_hand = Some("minecraft:bow".into());
+                mob.extra.set_main_hand(Some("minecraft:bow".into()));
             }
         }
         Species::IronGolem => {
@@ -298,7 +298,7 @@ fn entity_state(mob: &mut Mob, species: Species, case: &Value) {
             }
         }
         Species::Witch if flag("isHoldingItem") => {
-            mob.extra.main_hand = Some("minecraft:potion".into());
+            mob.extra.set_main_hand(Some("minecraft:potion".into()));
         }
         _ => {}
     }
@@ -386,7 +386,7 @@ pub fn main() -> horizon_client::Result<()> {
             .cloned()
             .unwrap_or_else(|| kind.model.clone());
         let mut mob = Mob::new(7, kind, Vec3::new(0.0, 64.0, 0.0), 0.0);
-        mob.extra.main_hand = None;
+        mob.extra.set_main_hand(None);
         let case = &v["case"];
         let f = |k: &str| case[k].as_f64().unwrap_or(0.0) as f32;
         if baby {

crates/horizon-client/examples/probe/entity_death_loot_fixture.rs

@@ -134,7 +134,7 @@ pub fn main() -> horizon_client::Result<()> {
                     let item: Option<Arc<str>> = Some(Arc::from(s.item.as_str()));
                     let index = match *slot {
                         "mainhand" => {
-                            m.extra.main_hand = item;
+                            m.extra.set_main_hand(item);
                             Some(gear::MAIN)
                         }
                         "offhand" => {

crates/horizon-client/examples/probe/mob_ai_probe.rs

@@ -733,6 +733,15 @@ fn print(out: &mut String, t: i32, i: usize, m: &Mob, player_down: bool, now: i6
             .map_or("-".into(), |p| format!("{},{},{}", p[0], p[1], p[2]));
         let _ = write!(out, "\tcg {} {held} {opened}", m.extra.variant3);
     }
+    if m.species() == Species::Wolf {
+        // NeutralMob anger left (the angry texture), -1 when calm.
+        let anger = if m.extra.anger > 0 {
+            i64::from(m.extra.anger)
+        } else {
+            -1
+        };
+        let _ = write!(out, "\twolf {anger}");
+    }
     if let Some(b) = horizon_client::mobs::bee::get(m) {
         let anger = if b.anger_end > 0 {
             b.anger_end - now

crates/horizon-client/examples/probe/pack_screen_fixture.rs

@@ -126,6 +126,7 @@ pub fn main() -> horizon_client::Result<()> {
             .collect();
         let mut screen = PackScreen::new(
             &m,
+            Text::translate(c["title"].as_str().unwrap_or("resourcePack.title"), &[]),
             int(&c["width"]),
             int(&c["height"]),
             c["inWorld"] == true,

crates/horizon-client/src/advancements.rs

@@ -877,6 +877,22 @@ pub fn item_entity(
         && item(&v["item"], stack, w)
 }
 
+/// `RecipeCraftedTrigger.TriggerInstance.matches`: each ingredient predicate
+/// takes a different one of the stacks used, in order.
+pub fn recipe_ingredients(v: &Value, used: &[ItemView], w: &dyn World) -> bool {
+    let Some(preds) = v.as_array() else {
+        return true;
+    };
+    let mut remaining: Vec<&ItemView> = used.iter().collect();
+    preds.iter().all(|p| {
+        let Some(i) = remaining.iter().position(|it| item(p, it, w)) else {
+            return false;
+        };
+        remaining.remove(i);
+        true
+    })
+}
+
 /// A `ContextAwarePredicate`: a list of loot conditions (or one condition).
 pub fn conditions(v: &Value, ctx: &Entities, w: &dyn World) -> bool {
     match v {

crates/horizon-client/src/crafting.rs

@@ -27,7 +27,7 @@ impl Ingredient {
     pub fn of(items: Vec<String>) -> Self {
         Self(items.iter().cloned().collect(), items)
     }
-    fn parse(v: &Value, items: &Items) -> Option<Self> {
+    pub(crate) fn parse(v: &Value, items: &Items) -> Option<Self> {
         let mut list: Vec<String> = Vec::new();
         let mut add = |s: &str| {
             let more: Vec<String> = match s.strip_prefix('#') {
@@ -43,14 +43,6 @@ impl Ingredient {
         match v {
             Value::String(s) => add(s),
             Value::Array(a) => a.iter().filter_map(Value::as_str).for_each(&mut add),
-            Value::Object(o) => {
-                if let Some(s) = o.get("item").and_then(Value::as_str) {
-                    add(s);
-                }
-                if let Some(t) = o.get("tag").and_then(Value::as_str) {
-                    add(&format!("#{t}"));
-                }
-            }
             _ => return None,
         }
         (!list.is_empty()).then(|| Self::of(list))

crates/horizon-client/src/creative.rs

@@ -527,6 +527,53 @@ impl Creative {
     pub fn scroller_offset(&self) -> f32 {
         ((Self::SCROLL_HEIGHT - 17.0) * self.scroll) as i32 as f32
     }
+    /// The tabs whose `CreativeModeTab.contains(stack)` holds, in
+    /// `CreativeModeTabs.tabs()` order, the search tab left out: the stack is
+    /// among the tab's search-tab items, by item and components. The export
+    /// lists each tab's own items; the search tab's stacks that no tab shows
+    /// (the enchanted books below their top level, `SEARCH_TAB_ONLY`) belong
+    /// to the tabs that show their item.
+    pub fn tabs_containing(&self, stack: &ItemStack) -> Vec<usize> {
+        let category = |t: &Tab| !t.search && !t.inventory;
+        let tabs_where = |shows: &dyn Fn(&ItemStack) -> bool| -> Vec<usize> {
+            (0..self.tabs.len())
+                .filter(|&i| category(&self.tabs[i]) && self.tabs[i].items.iter().any(shows))
+                .collect()
+        };
+        let found = tabs_where(&|s| same_components(s, stack));
+        if found.is_empty() && self.search_items.iter().any(|s| same_components(s, stack)) {
+            return tabs_where(&|s| s.item == stack.item);
+        }
+        found
+    }
+    /// The `#namespace:path` lines `getTooltipFromContainerItem` adds for a
+    /// search tab stack while the search is a `#` query: the item tags
+    /// `updateVisibleTags` keeps for the text after `#` (the path contains it;
+    /// with a colon, the namespace and the path each contain their part) that
+    /// the stack has.
+    pub fn search_tag_lines(&self, stack: &ItemStack) -> Vec<String> {
+        let Some(text) = self.search.value.strip_prefix('#') else {
+            return Vec::new();
+        };
+        let Some(entry) = self
+            .search_items
+            .iter()
+            .position(|s| same_components(s, stack))
+            .and_then(|i| self.search_index.get(i))
+        else {
+            return Vec::new();
+        };
+        let visible = |(ns, path): &(String, String)| match text.split_once(':') {
+            None => path.contains(text),
+            Some((n, p)) => ns.contains(java_trim(n)) && path.contains(java_trim(p)),
+        };
+        entry
+            .tags
+            .iter()
+            .filter(|t| visible(t))
+            .map(|(ns, path)| format!("#{ns}:{path}"))
+            .collect()
+    }
     /// Tab button position relative to the screen origin (CreativeModeInventoryScreen.getTabX/Y).
     pub fn tab_position(tab: &Tab) -> (f32, f32) {
         let mut x = tab.column as f32 * 27.0;
@@ -537,12 +584,35 @@ impl Creative {
         let y = if tab.top { -28.0 } else { Self::HEIGHT - 4.0 };
         (x, y)
     }
+    /// `CreativeModeInventoryScreen.extractTabButton`'s cursor: an unselected
+    /// tab asks for the pointing hand when the whole-pixel mouse, relative to
+    /// the screen origin, is strictly inside its 26x32 button.
+    pub fn tab_wants_hand(tab: &Tab, selected: bool, mouse: (f32, f32)) -> bool {
+        let (x, y) = Self::tab_position(tab);
+        let (mx, my) = (mouse.0.floor(), mouse.1.floor());
+        !selected && mx > x && my > y && mx < x + 26.0 && my < y + 32.0
+    }
 }
 /// Whether a suffix array of `strings` has a suffix starting with `text`:
 /// some string contains it (none for no strings, even when `text` is empty).
 fn any<'a>(strings: impl IntoIterator<Item = &'a str>, text: &str) -> bool {
     strings.into_iter().any(|s| s.contains(text))
 }
+/// `ItemStack.isSameItemSameComponents`, the count left out, as the
+/// tabs' `ItemStackLinkedSet` compares: no components and empty ones match.
+fn same_components(a: &ItemStack, b: &ItemStack) -> bool {
+    let none = crate::item_data::StackData::default();
+    a.item == b.item
+        && a.damage == b.damage
+        && a.data().unwrap_or(&none) == b.data().unwrap_or(&none)
+}
+/// `CreativeModeInventoryScreen.getTooltipFromContainerItem`: the plain
+/// tooltip only for a category tab's own grid slots (`CustomCreativeSlot`);
+/// everywhere else in the screen the tab names (and, on the search tab's
+/// grid, the tag lines) follow the item's name.
+pub fn tooltip_lists_tabs(category_tab: bool, grid_slot: bool) -> bool {
+    !(category_tab && grid_slot)
+}
 /// String.toLowerCase(Locale.ROOT).
 fn java_lower(s: &str) -> String {
     s.to_lowercase()
@@ -690,6 +760,109 @@ mod tests {
         (carried, effect)
     }
 
+    /// Tabs as the export lists them: two block tabs sharing the oak log,
+    /// ingredients with the top-level book only, the search tab with every
+    /// stack (a level 1 book only there) and its tags, the inventory.
+    fn tooltip_tabs() -> Creative {
+        let book = |level: u8| {
+            format!(
+                r#"{{components:{{"minecraft:stored_enchantments":{{"minecraft:sharpness":{level}}}}},count:1,id:"minecraft:enchanted_book"}}"#
+            )
+        };
+        let log = r#"{count:1,id:"minecraft:oak_log"}"#;
+        let dirt = r#"{count:1,id:"minecraft:dirt"}"#;
+        let tab = |id: &str, kind: &str, items: Vec<String>| serde_json::json!({"id": id, "type": kind, "title": id, "icon": log, "items": items});
+        let mut search = tab(
+            "minecraft:search",
+            "SEARCH",
+            vec![log.into(), dirt.into(), book(1), book(5)],
+        );
+        search["lines"] = serde_json::json!([[], [], [], []]);
+        search["tags"] = serde_json::json!([
+            [
+                "minecraft:logs",
+                "minecraft:oak_logs",
+                "minecraft:logs_that_burn"
+            ],
+            ["minecraft:dirt"],
+            [],
+            []
+        ]);
+        Creative::from_json(&serde_json::json!({"tabs": [
+            tab("minecraft:building_blocks", "CATEGORY", vec![log.into()]),
+            tab("minecraft:natural_blocks", "CATEGORY", vec![log.into(), dirt.into()]),
+            tab("minecraft:hotbar", "HOTBAR", vec![]),
+            search,
+            tab("minecraft:ingredients", "CATEGORY", vec![book(5)]),
+            tab("minecraft:inventory", "INVENTORY", vec![]),
+        ]}))
+        .unwrap()
+    }
+
+    #[test]
+    fn tooltip_lists_the_tabs_that_contain_the_stack() {
+        let c = tooltip_tabs();
+        let ids = |s: &ItemStack| -> Vec<&str> {
+            c.tabs_containing(s)
+                .into_iter()
+                .map(|i| c.tabs[i].id.as_str())
+                .collect()
+        };
+        // In tab order, the search and inventory tabs left out; the count
+        // doesn't matter.
+        assert_eq!(
+            ids(&stack("oak_log", 37)),
+            ["minecraft:building_blocks", "minecraft:natural_blocks"]
+        );
+        assert_eq!(ids(&stack("dirt", 1)), ["minecraft:natural_blocks"]);
+        // A stack no tab holds: other components, or no creative item.
+        let mut damaged = stack("oak_log", 1);
+        damaged.damage = 3;
+        assert!(ids(&damaged).is_empty());
+        assert!(ids(&stack("barrier", 1)).is_empty());
+        // A level 1 book is a search-tab-only stack of the ingredients tab.
+        let books: Vec<&ItemStack> = c
+            .search_items()
+            .iter()
+            .filter(|s| &*s.item == "minecraft:enchanted_book")
+            .collect();
+        assert_eq!(ids(books[0]), ["minecraft:ingredients"]);
+        assert_eq!(ids(books[1]), ["minecraft:ingredients"]);
+    }
+
+    #[test]
+    fn tooltip_tab_names_skip_only_a_category_tab_grid() {
+        assert!(!tooltip_lists_tabs(true, true));
+        // The hotbar row of a category tab, the search tab's grid and hotbar,
+        // the inventory tab.
+        assert!(tooltip_lists_tabs(true, false));
+        assert!(tooltip_lists_tabs(false, true));
+        assert!(tooltip_lists_tabs(false, false));
+    }
+
+    #[test]
+    fn tag_search_lists_the_matching_tags_of_the_stack() {
+        let mut c = tooltip_tabs();
+        let log = stack("oak_log", 1);
+        assert!(c.search_tag_lines(&log).is_empty());
+        c.search.set_value("logs");
+        assert!(c.search_tag_lines(&log).is_empty());
+        c.search.set_value("#logs");
+        assert_eq!(
+            c.search_tag_lines(&log),
+            [
+                "#minecraft:logs",
+                "#minecraft:oak_logs",
+                "#minecraft:logs_that_burn"
+            ]
+        );
+        c.search.set_value("#oak");
+        assert_eq!(c.search_tag_lines(&log), ["#minecraft:oak_logs"]);
+        c.search.set_value("#mine : burn");
+        assert_eq!(c.search_tag_lines(&log), ["#minecraft:logs_that_burn"]);
+        assert!(c.search_tag_lines(&stack("dirt", 1)).is_empty());
+    }
+
     #[test]
     fn search_tab_number_keys_swap_over_a_slot_before_typing() {
         let filled = Hover::Display { filled: true };
@@ -1006,4 +1179,38 @@ mod tests {
         c.search.key(KeyCode::Backspace, false, false);
         assert_eq!(c.search.value, "world");
     }
+
+    #[test]
+    fn unselected_tabs_want_the_hand_strictly_inside() {
+        let tab = |top, column| Tab {
+            id: String::new(),
+            title: String::new(),
+            icon: String::new(),
+            items: Vec::new(),
+            top,
+            column,
+            search: false,
+            inventory: false,
+        };
+        // Top row, second column: the button spans x 27..53, y -28..4.
+        let t = tab(true, 1);
+        assert!(Creative::tab_wants_hand(&t, false, (40.0, -10.0)));
+        assert!(!Creative::tab_wants_hand(&t, true, (40.0, -10.0)));
+        // Its edges ask for nothing; the mouse counts in whole pixels.
+        assert!(!Creative::tab_wants_hand(&t, false, (27.0, -10.0)));
+        assert!(!Creative::tab_wants_hand(&t, false, (27.9, -10.0)));
+        assert!(Creative::tab_wants_hand(&t, false, (28.0, -10.0)));
+        assert!(Creative::tab_wants_hand(&t, false, (52.9, -10.0)));
+        assert!(!Creative::tab_wants_hand(&t, false, (53.0, -10.0)));
+        assert!(!Creative::tab_wants_hand(&t, false, (40.0, -28.0)));
+        assert!(Creative::tab_wants_hand(&t, false, (40.0, -27.0)));
+        assert!(Creative::tab_wants_hand(&t, false, (40.0, 3.9)));
+        assert!(!Creative::tab_wants_hand(&t, false, (40.0, 4.0)));
+        // Bottom row, right-aligned inventory column: x 169..195, y 132..164.
+        let b = tab(false, 6);
+        assert!(Creative::tab_wants_hand(&b, false, (180.0, 140.0)));
+        assert!(!Creative::tab_wants_hand(&b, false, (169.0, 140.0)));
+        assert!(Creative::tab_wants_hand(&b, false, (170.0, 140.0)));
+        assert!(!Creative::tab_wants_hand(&b, false, (180.0, 132.0)));
+    }
 }

crates/horizon-client/src/debug_chart.rs

@@ -152,6 +152,14 @@ impl DebugCharts {
         }
         self.packet_tick = (self.packet_tick + 1) % 20;
     }
+    /// Whether `draw` (or the lightmap view) puts something in the bottom
+    /// left and the bottom right corner, for a `remote` server or not.
+    pub fn corners(&self, remote: bool) -> [bool; 2] {
+        [
+            self.fps || (self.network && remote),
+            (self.fps && !self.tick_times.is_empty()) || self.network || self.lightmap,
+        ]
+    }
     /// The charts along the bottom of the screen (`extractRenderState`):
     /// frame times left and tick times right, or bandwidth left (remote
     /// servers only) and ping right. `mspt` is the level's milliseconds
@@ -525,6 +533,26 @@ mod tests {
         assert!(overlay && c.fps);
     }
 
+    #[test]
+    fn corners_are_where_the_charts_are_drawn() {
+        let mut c = DebugCharts::default();
+        assert_eq!(c.corners(true), [false, false]);
+        // Frame times left; tick times right once the server logged a tick.
+        c.fps = true;
+        assert_eq!(c.corners(false), [true, false]);
+        c.tick_times.log(1);
+        assert_eq!(c.corners(false), [true, true]);
+        // Ping right; bandwidth left on a remote server only.
+        c.fps = false;
+        c.network = true;
+        assert_eq!(c.corners(false), [false, true]);
+        assert_eq!(c.corners(true), [true, true]);
+        // The lightmap view, bottom right.
+        c.network = false;
+        c.lightmap = true;
+        assert_eq!(c.corners(true), [false, true]);
+    }
+
     #[test]
     fn the_lightmap_puts_full_sky_light_at_the_top_left() {
         let mut pixels = [0u8; 16 * 16 * 4];

crates/horizon-client/src/dialog.rs

@@ -37,9 +37,11 @@ pub enum Kind {
         columns: i32,
         button_width: i32,
     },
-    /// `DialogListDialog`: its dialogs as sent (ids, a tag or inline dialogs).
+    /// `DialogListDialog`: its dialogs as sent (ids, a tag or inline dialogs),
+    /// and one button per dialog they resolve to (`set_list`).
     DialogList {
         dialogs: Tag,
+        entries: Vec<Button>,
         exit: Option<Button>,
         columns: i32,
         button_width: i32,
@@ -325,29 +327,36 @@ impl Control {
     fn parse(t: &Tag) -> Option<Self> {
         let label = || t.get("label").map(text);
         Some(match path(&string(t.get("type"))?) {
-            "text" => Self::Text {
-                width: int(t, "width", 200),
-                label: label()?,
-                label_visible: boolean(t, "label_visible", true),
-                initial: string(t.get("initial")).unwrap_or_default(),
-                max_length: int(t, "max_length", 32),
-                multiline: t.get("multiline").map(|m| {
-                    let get = |key| number(m.get(key)).map(|v| v as i32);
-                    (get("max_lines"), get("height"))
-                }),
-            },
+            "text" => {
+                let initial = string(t.get("initial")).unwrap_or_default();
+                let max_length = int(t, "max_length", 32);
+                // TextInput: the default text may not be longer than the length.
+                if initial.encode_utf16().count() > max_length.max(0) as usize {
+                    return None;
+                }
+                Self::Text {
+                    width: int(t, "width", 200),
+                    label: label()?,
+                    label_visible: boolean(t, "label_visible", true),
+                    initial,
+                    max_length,
+                    multiline: t.get("multiline").map(|m| {
+                        let get = |key| number(m.get(key)).map(|v| v as i32);
+                        (get("max_lines"), get("height"))
+                    }),
+                }
+            }
             "boolean" => Self::Boolean {
                 label: label()?,
                 initial: boolean(t, "initial", false),
                 on_true: string(t.get("on_true")).unwrap_or_else(|| "true".into()),
                 on_false: string(t.get("on_false")).unwrap_or_else(|| "false".into()),
             },
-            "single_option" => Self::SingleOption {
-                width: int(t, "width", 200),
+            "single_option" => {
                 // SingleOptionInput.Entry.CODEC: a full entry or just its id.
-                options: list(t.get("options"))
+                let options: Vec<_> = list(t.get("options"))
                     .iter()
-                    .filter_map(|o| match o {
+                    .map(|o| match o {
                         Tag::String(id) => Some((id.to_string_lossy(), None, false)),
                         o => Some((
                             string(o.get("id"))?,
@@ -355,10 +364,18 @@ impl Control {
                             boolean(o, "initial", false),
                         )),
                     })
-                    .collect(),
-                label: label()?,
-                label_visible: boolean(t, "label_visible", true),
-            },
+                    .collect::<Option<_>>()?;
+                // A non-empty list with at most one initial entry.
+                if options.is_empty() || options.iter().filter(|o| o.2).count() > 1 {
+                    return None;
+                }
+                Self::SingleOption {
+                    width: int(t, "width", 200),
+                    options,
+                    label: label()?,
+                    label_visible: boolean(t, "label_visible", true),
+                }
+            }
             "number_range" => {
                 let float = |key| number(t.get(key)).map(|v| v as f32);
                 Self::NumberRange {
@@ -395,6 +412,44 @@ impl Control {
             )),
         }
     }
+    /// The text on a cycle button or slider holding `value`
+    /// (`CycleButton.createFullName`, `NumberRangeInput.computeLabel`).
+    pub fn message(&self, value: &InputValue) -> Option<Text> {
+        match (self, value) {
+            (
+                Self::SingleOption {
+                    options,
+                    label,
+                    label_visible,
+                    ..
+                },
+                InputValue::Option(i),
+            ) => {
+                let (id, display, _) = options.get(*i)?;
+                let shown = display.clone().unwrap_or_else(|| Text::literal(id));
+                Some(if *label_visible {
+                    Text::translate("options.generic_value", &[label.clone(), shown])
+                } else {
+                    shown
+                })
+            }
+            (
+                Self::NumberRange {
+                    label,
+                    label_format,
+                    ..
+                },
+                InputValue::Slider(_),
+            ) => {
+                let shown = number_string(self.scaled(value)?);
+                Some(Text::translate(
+                    label_format,
+                    &[label.clone(), Text::literal(shown)],
+                ))
+            }
+            _ => None,
+        }
+    }
     /// `ValueGetter.asTemplateSubstitution`.
     pub fn substitution(&self, value: &InputValue) -> String {
         match (self, value) {
@@ -536,6 +591,7 @@ impl Dialog {
             },
             "dialog_list" => Kind::DialogList {
                 dialogs: t.get("dialogs")?.clone(),
+                entries: Vec::new(),
                 exit: button("exit_action"),
                 columns: int(t, "columns", 2),
                 button_width: int(t, "button_width", 150),
@@ -543,20 +599,21 @@ impl Dialog {
             _ => return None,
         };
         // DialogBody.COMPACT_LIST_CODEC: one body, or a list of them.
+        // A body or input it cannot read fails the whole dialog.
         let body = match t.get("body") {
-            Some(Tag::List(items)) => items.iter().filter_map(Body::parse).collect(),
-            Some(one) => Body::parse(one).into_iter().collect(),
+            Some(Tag::List(items)) => items.iter().map(Body::parse).collect::<Option<_>>()?,
+            Some(one) => vec![Body::parse(one)?],
             None => Vec::new(),
         };
         let inputs = list(t.get("inputs"))
             .iter()
-            .filter_map(|i| {
+            .map(|i| {
                 Some(Input {
                     key: string(i.get("key"))?,
                     control: Control::parse(i)?,
                 })
             })
-            .collect();
+            .collect::<Option<_>>()?;
         Some(Self {
             kind,
             title: text(t.get("title")?),
@@ -588,7 +645,51 @@ impl Dialog {
             Kind::Notice(b) => vec![b],
             Kind::Confirmation { yes, no } => vec![yes, no],
             Kind::MultiAction { actions, exit, .. } => actions.iter().chain(exit).collect(),
-            Kind::ServerLinks { exit, .. } | Kind::DialogList { exit, .. } => exit.iter().collect(),
+            Kind::ServerLinks { exit, .. } => exit.iter().collect(),
+            Kind::DialogList { entries, exit, .. } => entries.iter().chain(exit).collect(),
+        }
+    }
+    /// `DialogListDialogScreen.createListActions`: a button for each of `dialogs`
+    /// (what the list names), labelled by its external title, opening it.
+    pub fn set_list(&mut self, dialogs: &[Tag]) {
+        let Kind::DialogList {
+            entries,
+            button_width,
+            ..
+        } = &mut self.kind
+        else {
+            return;
+        };
+        *entries = dialogs
+            .iter()
+            .filter_map(|tag| {
+                let sub = Dialog::parse(tag)?;
+                Some(Button {
+                    label: sub.external_title.unwrap_or(sub.title),
+                    tooltip: None,
+                    width: *button_width,
+                    action: Some(Action::Static(Click::ShowDialog(tag.clone()))),
+                })
+            })
+            .collect();
+    }
+    /// The dialogs a `dialog_list`'s `dialogs` names: the entries of a `#tag`
+    /// (by `tag`), registry ids (by `registry`) and dialogs written inline.
+    pub fn list_entries(
+        dialogs: &Tag,
+        tag: &dyn Fn(&str) -> Vec<Tag>,
+        registry: &dyn Fn(&str) -> Option<Tag>,
+    ) -> Vec<Tag> {
+        let one = |t: &Tag| match t {
+            Tag::String(id) => registry(&id.to_string_lossy()),
+            inline => Some(inline.clone()),
+        };
+        match dialogs {
+            Tag::String(id) if id.to_string_lossy().starts_with('#') => {
+                tag(&id.to_string_lossy()[1..])
+            }
+            Tag::List(items) => items.iter().filter_map(one).collect(),
+            single => one(single).into_iter().collect(),
         }
     }
     /// What `status` reports of it.

crates/horizon-client/src/dialog_screen.rs

@@ -31,6 +31,44 @@ pub enum Part {
     Check { input: usize, rect: [f32; 4] },
     /// A button of `Dialog::buttons`.
     Button { index: usize, rect: [f32; 4] },
+    /// A single option input's cycle button.
+    Cycle { input: usize, rect: [f32; 4] },
+    /// A number range input's slider.
+    Slider { input: usize, rect: [f32; 4] },
+    /// An item body's widget; `body` indexes `Dialog::body`.
+    Item { body: usize, rect: [f32; 4] },
+}
+impl Part {
+    /// The part moved by `(dx, dy)`.
+    fn moved(self, dx: f32, dy: f32) -> Self {
+        match self {
+            Self::Line(t, x, y) => Self::Line(t, x + dx, y + dy),
+            Self::Field { input, rect } => Self::Field {
+                input,
+                rect: shift(rect, dx, dy),
+            },
+            Self::Check { input, rect } => Self::Check {
+                input,
+                rect: shift(rect, dx, dy),
+            },
+            Self::Button { index, rect } => Self::Button {
+                index,
+                rect: shift(rect, dx, dy),
+            },
+            Self::Cycle { input, rect } => Self::Cycle {
+                input,
+                rect: shift(rect, dx, dy),
+            },
+            Self::Slider { input, rect } => Self::Slider {
+                input,
+                rect: shift(rect, dx, dy),
+            },
+            Self::Item { body, rect } => Self::Item {
+                body,
+                rect: shift(rect, dx, dy),
+            },
+        }
+    }
 }
 
 #[derive(Clone, Debug)]
@@ -55,21 +93,7 @@ struct Element {
 impl Element {
     /// Its parts moved to `(x, y)`.
     fn at(self, x: f32, y: f32) -> impl Iterator<Item = Part> {
-        self.parts.into_iter().map(move |p| match p {
-            Part::Line(t, px, py) => Part::Line(t, px + x, py + y),
-            Part::Field { input, rect } => Part::Field {
-                input,
-                rect: shift(rect, x, y),
-            },
-            Part::Check { input, rect } => Part::Check {
-                input,
-                rect: shift(rect, x, y),
-            },
-            Part::Button { index, rect } => Part::Button {
-                index,
-                rect: shift(rect, x, y),
-            },
-        })
+        self.parts.into_iter().map(move |p| p.moved(x, y))
     }
 }
 fn shift([x, y, w, h]: [f32; 4], dx: f32, dy: f32) -> [f32; 4] {
@@ -100,9 +124,43 @@ fn message(font: &Font, contents: &Text, width: f32) -> Element {
     }
 }
 
-/// `InputControlHandlers`: the control for input `i`, if Horizon has it.
-fn input(font: &Font, i: usize, control: &Control) -> Option<Element> {
-    Some(match control {
+/// `DialogBodyHandlers.ItemHandler`: the item widget, with its description 2
+/// to the right of it, both centred on each other vertically.
+fn item(
+    font: &Font,
+    body: usize,
+    description: Option<&(Text, i32)>,
+    (w, h): (f32, f32),
+) -> Element {
+    let widget = |rect_h: f32, y: f32| Part::Item {
+        body,
+        rect: [0.0, y, w, rect_h],
+    };
+    let Some((contents, width)) = description else {
+        return Element {
+            w,
+            h,
+            parts: vec![widget(h, 0.0)],
+        };
+    };
+    let text = message(font, contents, *width as f32);
+    let height = h.max(text.h);
+    let mut parts = vec![widget(h, centre(height, h))];
+    parts.extend(
+        text.parts
+            .into_iter()
+            .map(|p| p.moved(w + 2.0, centre(height, text.h))),
+    );
+    Element {
+        w: w + 2.0 + text.w,
+        h: height,
+        parts,
+    }
+}
+
+/// `InputControlHandlers`: the control for input `i`.
+fn input(font: &Font, i: usize, control: &Control) -> Element {
+    match control {
         Control::Text {
             width,
             label,
@@ -111,14 +169,14 @@ fn input(font: &Font, i: usize, control: &Control) -> Option<Element> {
         } => {
             let w = *width as f32;
             if !label_visible {
-                return Some(Element {
+                return Element {
                     w,
                     h: 20.0,
                     parts: vec![Part::Field {
                         input: i,
                         rect: [0.0, 0.0, w, 20.0],
                     }],
-                });
+                };
             }
             // CommonLayouts.labeledElement: the label, 4 below it the box,
             // both on the left.
@@ -145,8 +203,25 @@ fn input(font: &Font, i: usize, control: &Control) -> Option<Element> {
                 }],
             }
         }
-        Control::SingleOption { .. } | Control::NumberRange { .. } => return None,
-    })
+        // CycleButton and AbstractSliderButton: one 20 high button whose
+        // message holds the label.
+        Control::SingleOption { width, .. } => Element {
+            w: *width as f32,
+            h: 20.0,
+            parts: vec![Part::Cycle {
+                input: i,
+                rect: [0.0, 0.0, *width as f32, 20.0],
+            }],
+        },
+        Control::NumberRange { width, .. } => Element {
+            w: *width as f32,
+            h: 20.0,
+            parts: vec![Part::Slider {
+                input: i,
+                rect: [0.0, 0.0, *width as f32, 20.0],
+            }],
+        },
+    }
 }
 
 /// `DialogScreen.packControlsIntoColumns`: full rows in a grid 2 apart, what
@@ -210,9 +285,20 @@ impl Layout {
         let mut elements: Vec<Element> = dialog
             .body
             .iter()
-            .filter_map(|b| match b {
-                Body::Message { contents, width } => Some(message(font, contents, *width as f32)),
-                Body::Item { .. } => None,
+            .enumerate()
+            .map(|(i, b)| match b {
+                Body::Message { contents, width } => message(font, contents, *width as f32),
+                Body::Item {
+                    description,
+                    width,
+                    height,
+                    ..
+                } => item(
+                    font,
+                    i,
+                    description.as_ref(),
+                    (*width as f32, *height as f32),
+                ),
             })
             .collect();
         elements.extend(
@@ -220,26 +306,24 @@ impl Layout {
                 .inputs
                 .iter()
                 .enumerate()
-                .filter_map(|(i, input_)| input(font, i, &input_.control)),
+                .map(|(i, input_)| input(font, i, &input_.control)),
         );
         let buttons = dialog.buttons();
         let (listed, footer_buttons, footer_h) = match &dialog.kind {
             Kind::MultiAction {
-                actions,
-                exit,
-                columns: n,
+                exit, columns: n, ..
+            }
+            | Kind::DialogList {
+                exit, columns: n, ..
             } => {
-                let widths: Vec<f32> = actions.iter().map(|b| b.width as f32).collect();
+                let listed = buttons.len() - usize::from(exit.is_some());
+                let widths: Vec<f32> = buttons[..listed].iter().map(|b| b.width as f32).collect();
                 elements.push(columns(&widths, *n as usize, 0));
                 // ButtonListDialogScreen: the exit button in the footer, else a 5 high one.
-                let footer = exit.as_ref().map(|_| actions.len()).into_iter().collect();
-                (
-                    actions.len(),
-                    footer,
-                    if exit.is_some() { BAR } else { 5.0 },
-                )
+                let footer = exit.as_ref().map(|_| listed).into_iter().collect();
+                (listed, footer, if exit.is_some() { BAR } else { 5.0 })
             }
-            Kind::ServerLinks { exit, .. } | Kind::DialogList { exit, .. } => {
+            Kind::ServerLinks { exit, .. } => {
                 let footer = exit.as_ref().map(|_| 0).into_iter().collect();
                 (0, footer, if exit.is_some() { BAR } else { 5.0 })
             }
@@ -303,24 +387,10 @@ impl Layout {
     /// whether it is in the body (clipped to its area).
     pub fn placed(&self, scroll: f32) -> impl Iterator<Item = (Part, bool)> + '_ {
         let dy = self.area[1] - scroll;
-        let body = self.body.iter().map(move |p| {
-            let p = match p.clone() {
-                Part::Line(t, x, y) => Part::Line(t, x, y + dy),
-                Part::Field { input, rect } => Part::Field {
-                    input,
-                    rect: shift(rect, 0.0, dy),
-                },
-                Part::Check { input, rect } => Part::Check {
-                    input,
-                    rect: shift(rect, 0.0, dy),
-                },
-                Part::Button { index, rect } => Part::Button {
-                    index,
-                    rect: shift(rect, 0.0, dy),
-                },
-            };
-            (p, true)
-        });
+        let body = self
+            .body
+            .iter()
+            .map(move |p| (p.clone().moved(0.0, dy), true));
         body.chain(self.footer.iter().map(|p| (p.clone(), false)))
     }
 }

crates/horizon-client/src/end_gateway.rs

@@ -0,0 +1,159 @@
+//! End gateway travel for the entities that step into one:
+//! `EndGatewayBlock.entityInside` (the gateway takes the entity in and starts
+//! its 40 tick cooldown), `Entity.setAsInsidePortal` and `Entity.handlePortal`
+//! (the entity goes through on the next tick), and
+//! `TheEndGatewayBlockEntity.getPortalPosition` (where it lands).
+use crate::nether_portal::{ENTITY_DELAY, PortalState};
+use horizon_core::{geometry::Vec3, position::BlockPos};
+
+/// The End gateway travel of one entity.
+#[derive(Clone, Copy, Debug, Default)]
+pub struct Traveller {
+    /// The entity's portal process and cooldown (`Entity.portalProcess`).
+    state: PortalState,
+}
+
+impl Traveller {
+    /// `Entity.setAsInsidePortal`: the entity is in the gateway and goes
+    /// through it on the next tick.
+    pub fn enter(&mut self, gateway: BlockPos) {
+        self.state.set_inside(gateway, ENTITY_DELAY);
+    }
+
+    /// `Entity.handlePortal`: the entity goes through the gateway it entered
+    /// (the End gateway has no transition time), or stays where it is.
+    pub fn travel(&mut self, allowed: bool) -> Option<BlockPos> {
+        self.state.handle(allowed, 0, ENTITY_DELAY)
+    }
+
+    /// Whether the entity's travel is over: it has no portal process left and
+    /// its portal cooldown has run out.
+    pub fn is_done(&self) -> bool {
+        self.state.cooldown == 0 && self.state.process.is_none()
+    }
+
+    /// The entity's portal cooldown, the ticks it stays out of a portal.
+    pub fn cooldown(&self) -> i32 {
+        self.state.cooldown
+    }
+}
+
+/// The End gateway block an entity's box swept through
+/// (`Entity.checkInsideBlocks`, which calls `EndGatewayBlock.entityInside`).
+pub fn swept_gateway(
+    from: Vec3,
+    to: Vec3,
+    width: f32,
+    height: f32,
+    mut is_gateway: impl FnMut(BlockPos) -> bool,
+) -> Option<BlockPos> {
+    let half = f64::from(width) / 2.0;
+    let bounds = horizon_core::geometry::Aabb::new(
+        Vec3::new(to.x - half, to.y, to.z - half),
+        Vec3::new(to.x + half, to.y + f64::from(height), to.z + half),
+    )
+    .deflate(Vec3::new(1.0e-5, 1.0e-5, 1.0e-5));
+    let mut found = None;
+    let _ =
+        horizon_core::geometry::sweep_intersected_blocks(from, to, bounds, 1_000_000, |p, _| {
+            if is_gateway(p) {
+                found = Some(p);
+                return false;
+            }
+            true
+        });
+    found
+}
+
+/// The bottom centre of a block (`Vec3.atBottomCenterOf`): where a traveller
+/// lands at a gateway's exit.
+pub fn bottom_center(p: [i32; 3]) -> Vec3 {
+    Vec3::new(
+        f64::from(p[0]) + 0.5,
+        f64::from(p[1]),
+        f64::from(p[2]) + 0.5,
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// The gateway of the issue: a block at [702, 100, 0] in the End.
+    const GATEWAY: [i32; 3] = [702, 100, 0];
+
+    fn at(x: f64, y: f64, z: f64) -> Vec3 {
+        Vec3::new(x, y, z)
+    }
+
+    fn is_gateway(p: BlockPos) -> bool {
+        [p.x, p.y, p.z] == GATEWAY
+    }
+
+    #[test]
+    fn an_item_and_a_mob_in_a_gateway_are_found_in_it() {
+        // A dropped item, 0.25 wide, standing in the gateway block.
+        let item = at(702.5, 100.5, 0.5);
+        assert_eq!(
+            swept_gateway(item, item, 0.25, 0.25, is_gateway),
+            Some(BlockPos::new(702, 100, 0))
+        );
+        // A cow, 0.9 wide and 1.4 tall, in the same block.
+        let cow = at(702.5, 100.0, 0.5);
+        assert_eq!(
+            swept_gateway(cow, cow, 0.9, 1.4, is_gateway),
+            Some(BlockPos::new(702, 100, 0))
+        );
+    }
+
+    #[test]
+    fn an_entity_out_of_the_gateway_is_not_in_it() {
+        // Two blocks above the gateway: nothing to travel through.
+        let above = at(702.5, 102.5, 0.5);
+        assert_eq!(swept_gateway(above, above, 0.25, 0.25, is_gateway), None);
+        // Beside the gateway, outside its block.
+        let beside = at(704.5, 100.5, 0.5);
+        assert_eq!(swept_gateway(beside, beside, 0.9, 1.4, is_gateway), None);
+    }
+
+    #[test]
+    fn an_entity_falling_through_the_gateway_goes_through_it() {
+        // A cow falling past the gateway block passes through it
+        // (Entity.checkInsideBlocks visits the blocks along the way).
+        let from = at(702.5, 103.0, 0.5);
+        let to = at(702.5, 99.0, 0.5);
+        assert_eq!(
+            swept_gateway(from, to, 0.9, 1.4, is_gateway),
+            Some(BlockPos::new(702, 100, 0))
+        );
+    }
+    #[test]
+    fn an_entity_goes_through_the_gateway_on_the_tick_after_it_entered() {
+        let gateway = BlockPos::new(702, 100, 0);
+        let mut traveller = Traveller::default();
+        // Nothing happens while the entity is outside the gateway.
+        assert_eq!(traveller.travel(true), None);
+        // It enters the gateway, and goes through on the next tick.
+        traveller.enter(gateway);
+        assert_eq!(traveller.travel(true), Some(gateway));
+        // Its portal cooldown keeps it from going back at once.
+        assert_eq!(traveller.cooldown(), ENTITY_DELAY);
+        assert!(!traveller.is_done());
+    }
+
+    #[test]
+    fn an_entity_that_may_not_use_portals_stays_in_the_gateway() {
+        let gateway = BlockPos::new(702, 100, 0);
+        let mut traveller = Traveller::default();
+        traveller.enter(gateway);
+        // A mob that cannot use a portal does not go through.
+        assert_eq!(traveller.travel(false), None);
+    }
+
+    #[test]
+    fn a_traveller_lands_at_the_bottom_centre_of_the_exit() {
+        // TheEndGatewayBlockEntity.getPortalPosition: the exit's bottom
+        // centre, the same spot the player arrives at.
+        assert_eq!(bottom_center([8, 100, 0]), at(8.5, 100.0, 0.5));
+    }
+}

crates/horizon-client/src/entity_nbt.rs

@@ -759,6 +759,17 @@ pub fn mob_to_nbt(m: &Mob, uuid: [i32; 4], raw: Option<&Tag>) -> Tag {
         .into_iter()
         .enumerate()
         {
+            if slot == "mainhand"
+                && let Some(stack) = m.extra.main_hand_stack()
+            {
+                let mut stack = stack.clone();
+                if let Some(g) = crate::mobs::gear::gear(m) {
+                    stack.data_mut().enchantments = g.slots[index].clone();
+                    stack.data_mut().trim = g.trims[index].clone();
+                }
+                equipment.insert(slot.into(), crate::save::item_to_nbt(&stack));
+                continue;
+            }
             // Enchanted or trimmed gear is saved with its components.
             if let (Some(id), Some(g)) = (item, crate::mobs::gear::gear(m))
                 && (!g.slots[index].is_empty() || g.trims[index].is_some())
@@ -782,10 +793,11 @@ pub fn mob_to_nbt(m: &Mob, uuid: [i32; 4], raw: Option<&Tag>) -> Tag {
             }
             match item {
                 Some(id) => {
-                    let keep = matches!(
-                        equipment.get(&slot.into()).and_then(|e| e.get("id")),
-                        Some(Tag::String(s)) if s.to_string_lossy() == **id
-                    );
+                    let keep = slot != "mainhand"
+                        && matches!(
+                            equipment.get(&slot.into()).and_then(|e| e.get("id")),
+                            Some(Tag::String(s)) if s.to_string_lossy() == **id
+                        );
                     if slot == "head"
                         && &**id == crate::mobs::raider::BANNER
                         && crate::mobs::raider::is_raider(m.species())
@@ -953,7 +965,20 @@ pub fn mob_from_nbt(tag: &Tag, types: &HashMap<String, Arc<MobType>>, id: u32) -
                 continue;
             };
             let v = f64::from_bits(*bits);
+            // A mount's rolled health and speed stay attribute bases, which
+            // the server syncs (its hearts over the rider's hotbar).
+            let equine = crate::mobs::equine::is_equine(m.species());
             match id.as_str() {
+                "minecraft:max_health" if equine => crate::mobs::finalize::set_base(
+                    &mut m,
+                    crate::mobs::finalize::Attr::MaxHealth,
+                    v,
+                ),
+                "minecraft:movement_speed" if equine => crate::mobs::finalize::set_base(
+                    &mut m,
+                    crate::mobs::finalize::Attr::MovementSpeed,
+                    v,
+                ),
                 "minecraft:max_health" => m.attrs.max_health = v as f32,
                 "minecraft:movement_speed" => m.attrs.speed = v,
                 "minecraft:attack_damage" => m.attrs.attack_damage = v as f32,
@@ -976,10 +1001,8 @@ pub fn mob_from_nbt(tag: &Tag, types: &HashMap<String, Arc<MobType>>, id: u32) -
     m.hurt_time = number(tag.get("HurtTime")).unwrap_or(0) as i32;
     // What it holds (equipment.mainhand / offhand), when saved.
     if let Some(eq) = tag.get("equipment") {
-        m.extra.main_hand = eq
-            .get("mainhand")
-            .and_then(|i| text(i.get("id")))
-            .map(Into::into);
+        m.extra
+            .set_main_hand_stack(eq.get("mainhand").and_then(crate::save::item_from_nbt));
         m.extra.off_hand = eq
             .get("offhand")
             .and_then(|i| text(i.get("id")))
@@ -1006,7 +1029,7 @@ pub fn mob_from_nbt(tag: &Tag, types: &HashMap<String, Arc<MobType>>, id: u32) -
     } else {
         // Registration hands out default weapons (finalizeSpawn does in
         // vanilla); a loaded mob holds only what its file lists.
-        m.extra.main_hand = None;
+        m.extra.set_main_hand(None);
     }
     m.death_time = number(tag.get("DeathTime")).unwrap_or(0) as i32;
     // Mob.readAdditionalSaveData overrides what the constructor set (copper
@@ -3120,3 +3143,51 @@ mod neutral_anger_tests {
         assert_eq!(crate::mobs::anger_left(3000, 4000), 0);
     }
 }
+
+#[cfg(test)]
+mod held_item_name_tests {
+    use super::*;
+
+    #[test]
+    fn replacing_a_named_item_does_not_restore_its_old_name_on_save() {
+        let root = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("../../.local/horizon-client")
+            .join(horizon_core::VANILLA_VERSION);
+        if !root.join("items.json").exists() {
+            return;
+        }
+        let data = crate::mobs::MobTypes::load(&root).unwrap();
+        let types: HashMap<_, _> = data
+            .types
+            .into_iter()
+            .map(|(id, kind)| (id, Arc::new(kind)))
+            .collect();
+        let mut mob = Mob::new(1, Arc::clone(&types["minecraft:zombie"]), Vec3::ZERO, 0.0);
+        let mut sword = crate::items::ItemStack::new("minecraft:diamond_sword", 1);
+        sword.data_mut().custom_name = Some("Old Sword".into());
+        mob.extra.set_main_hand_stack(Some(sword));
+        let raw = mob_to_nbt(&mob, [1, 2, 3, 4], None);
+        let mut loaded = mob_from_nbt(&raw, &types, 2).unwrap();
+        assert_eq!(
+            loaded.extra.main_hand_stack().unwrap().custom_name(),
+            Some("Old Sword")
+        );
+        loaded
+            .extra
+            .set_main_hand(Some("minecraft:diamond_sword".into()));
+        let saved = mob_to_nbt(&loaded, [1, 2, 3, 4], Some(&raw));
+        let restored = mob_from_nbt(&saved, &types, 3).unwrap();
+        assert_eq!(
+            restored.extra.main_hand.as_deref(),
+            Some("minecraft:diamond_sword")
+        );
+        assert!(
+            restored
+                .extra
+                .main_hand_stack()
+                .unwrap()
+                .custom_name()
+                .is_none()
+        );
+    }
+}

crates/horizon-client/src/first_person.rs

@@ -12,6 +12,8 @@
 #[derive(Clone, Copy, Debug)]
 pub enum ItemPose {
     Swing,
+    /// A STAB swing (`SwingAnimationType` 2): a spear's jab.
+    Stab,
     Using,
     Eat {
         remaining: f32,
@@ -86,6 +88,9 @@ pub fn item_pose(left: bool, inverse_height: f32, attack: f32, pose: ItemPose) -
         return Mat4::from_translation(Vec3::new(invert * 0.56, -0.52, -0.72))
             * crate::spear::first_person_use(&kinetic, ticks_since_hit, time_held, !left);
     }
+    if matches!(pose, ItemPose::Stab) {
+        return m * crate::spear::first_person_attack(attack, !left);
+    }
     if matches!(pose, ItemPose::SpinAttack) {
         return m
             * Mat4::from_translation(Vec3::new(invert * -0.4, 0.8, 0.3))
@@ -172,8 +177,94 @@ impl MapHold {
     }
 }
 
+/// `renderPlayerArm` up to `renderPlayerHand`: the pose of the bare `left`
+/// or right arm.
+pub fn player_arm_pose(left: bool, inverse_height: f32, attack: f32) -> glam::Mat4 {
+    use glam::{Mat4, Vec3};
+    use horizon_core::geometry::trig::Mth;
+    let f = if left { -1.0 } else { 1.0 };
+    let pi = std::f32::consts::PI;
+    let root = attack.sqrt();
+    let x = -0.3 * (root * pi).msin();
+    let y = 0.4 * (root * std::f32::consts::TAU).msin();
+    let z = -0.4 * (attack * pi).msin();
+    let z_rot = (attack * attack * pi).msin();
+    let y_rot = (root * pi).msin();
+    let deg = |d: f32| d.to_radians();
+    Mat4::from_translation(Vec3::new(
+        f * (x + 0.640_000_05),
+        y - 0.6 + inverse_height * -0.6,
+        z + -0.719_999_97,
+    )) * Mat4::from_rotation_y(deg(f * 45.0))
+        * Mat4::from_rotation_y(deg(f * y_rot * 70.0))
+        * Mat4::from_rotation_z(deg(f * z_rot * -20.0))
+        * Mat4::from_translation(Vec3::new(-f, 3.6, 3.5))
+        * Mat4::from_rotation_z(deg(f * 120.0))
+        * Mat4::from_rotation_x(deg(200.0))
+        * Mat4::from_rotation_y(deg(f * -135.0))
+        * Mat4::from_translation(Vec3::new(f * 5.6, 0.0, 0.0))
+}
+
+/// `renderTwoHandedMap` up to its arms: the swing, the tilt from the view
+/// pitch (`calculateMapTilt`) and the turn towards the player.
+pub fn two_handed_map_base(pitch: f32, inverse_height: f32, attack: f32) -> glam::Mat4 {
+    use glam::{Mat4, Vec3};
+    use horizon_core::geometry::trig::Mth;
+    let pi = std::f32::consts::PI;
+    let y_swing = -0.2 * (attack * pi).msin();
+    let z_swing = -0.4 * (attack.sqrt() * pi).msin();
+    let tilt = (1.0 - pitch / 45.0 + 0.1).clamp(0.0, 1.0);
+    let tilt = -(tilt * pi).mcos() * 0.5 + 0.5;
+    Mat4::from_translation(Vec3::new(0.0, -y_swing / 2.0, z_swing))
+        * Mat4::from_translation(Vec3::new(
+            0.0,
+            0.04 + inverse_height * -1.2 + tilt * -0.5,
+            -0.72,
+        ))
+        * Mat4::from_rotation_x((tilt * -85.0).to_radians())
+}
+
+/// The arms under a held map, as (left arm, pose before `renderPlayerHand`):
+/// `renderOneHandedMap`'s arm turned 10 degrees outwards, or
+/// `renderTwoHandedMap`'s two `renderMapHand` arms under the map's
+/// `two_handed_map_base`. Vanilla skips them for an invisible player.
+pub fn map_arm_poses(
+    hold: MapHold,
+    left: bool,
+    pitch: f32,
+    inverse_height: f32,
+    attack: f32,
+) -> Vec<(bool, glam::Mat4)> {
+    use glam::{Mat4, Vec3};
+    let deg = |d: f32| d.to_radians();
+    match hold {
+        MapHold::OneHanded => {
+            let f = if left { -1.0 } else { 1.0 };
+            let m = Mat4::from_translation(Vec3::new(f * 0.125, -0.125, 0.0))
+                * Mat4::from_rotation_z(deg(f * 10.0))
+                * player_arm_pose(left, inverse_height, attack);
+            vec![(left, m)]
+        }
+        MapHold::TwoHanded => {
+            let base = two_handed_map_base(pitch, inverse_height, attack)
+                * Mat4::from_rotation_y(deg(90.0));
+            [false, true]
+                .into_iter()
+                .map(|left| {
+                    let f = if left { -1.0 } else { 1.0 };
+                    let hand = Mat4::from_rotation_y(deg(92.0))
+                        * Mat4::from_rotation_x(deg(45.0))
+                        * Mat4::from_rotation_z(deg(f * -41.0))
+                        * Mat4::from_translation(Vec3::new(f * 0.3, -1.1, 0.45));
+                    (left, base * hand)
+                })
+                .collect()
+        }
+    }
+}
+
 /// `renderOneHandedMap` up to `renderMap`: the pose of a map in the hand on
-/// the `left` or right arm (the arm under it is not drawn).
+/// the `left` or right arm (its arm: [`map_arm_poses`]).
 pub fn one_handed_map_pose(left: bool, inverse_height: f32, attack: f32) -> glam::Mat4 {
     use glam::{Mat4, Vec3};
     use horizon_core::geometry::trig::Mth;
@@ -945,6 +1036,83 @@ mod item_pose_tests {
         }
     }
     #[test]
+    fn maps_draw_the_arms_under_them_as_vanilla() {
+        // PoseStack.last().pose() (column-major) where renderOneHandedMap's
+        // renderPlayerArm and renderTwoHandedMap's renderMapHand call
+        // renderPlayerHand, replayed with vanilla's PoseStack, Axis and Mth.
+        let near = |got: glam::Mat4, want: [f32; 16], what: &str| {
+            let got = got.to_cols_array();
+            for (g, w) in got.iter().zip(want) {
+                assert!((g - w).abs() < 1e-5, "{what}: {got:?}");
+            }
+        };
+        // (left, inverse height, attack, arm)
+        #[rustfmt::skip]
+        let one: [(bool, f32, f32, [f32; 16]); 3] = [
+            (false, 0.0, 0.0, [
+                -0.2350201, -0.7860474, -0.5717472, 0.0,
+                0.24694103, 0.52063686, -0.8172866, 0.0,
+                0.9400987, -0.33326668, 0.07174723, 0.0,
+                0.65913033, -1.1543381, -0.73980355, 1.0,
+            ]),
+            (true, 0.25, 0.3, [
+                -0.4967606, 0.84289914, -0.20676011, 0.0,
+                0.7202682, 0.2674863, -0.6400506, 0.0,
+                -0.4841926, -0.46687466, -0.7399901, 0.0,
+                -0.59715486, -1.4160433, -0.7328731, 1.0,
+            ]),
+            (false, 0.6, 0.85, [
+                -0.47358897, -0.8403256, -0.2637542, 0.0,
+                0.081554025, 0.25634, -0.96313995, 0.0,
+                0.87696207, -0.47764266, -0.052867785, 0.0,
+                0.61887383, -1.6482887, -0.7229744, 1.0,
+            ]),
+        ];
+        for (left, inverse_height, attack, want) in one {
+            let arms = map_arm_poses(MapHold::OneHanded, left, 0.0, inverse_height, attack);
+            assert_eq!(arms.len(), 1, "one arm under a one-handed map");
+            assert_eq!(arms[0].0, left, "the arm of the hand holding it");
+            near(
+                arms[0].1,
+                want,
+                &format!("one {left} {inverse_height} {attack}"),
+            );
+        }
+        // (pitch, inverse height, attack, right arm, left arm)
+        #[rustfmt::skip]
+        let two: [(f32, f32, f32, [f32; 16], [f32; 16]); 2] = [
+            (0.0, 0.0, 0.0, [
+                -0.7380599, 0.44766384, 0.50484115, 0.0,
+                -0.67428374, -0.46198538, -0.57611704, 0.0,
+                -0.024677532, -0.76561517, 0.64282537, 0.0,
+                0.5091893, -0.16204369, 0.3544525, 1.0,
+            ], [
+                -0.77043974, -0.3951866, -0.50025004, 0.0,
+                0.637035, -0.5076031, -0.58010805, 0.0,
+                -0.024677532, -0.76561517, 0.64282537, 0.0,
+                -0.48071152, -0.12760738, 0.35746527, 1.0,
+            ]),
+            (30.0, 0.2, 0.5, [
+                -0.7380599, -0.11453738, 0.6649426, 0.0,
+                -0.67428374, 0.16124588, -0.72065324, 0.0,
+                -0.024677532, -0.98024535, -0.1962398, 0.0,
+                0.5091893, -0.9508533, -0.13439482, 1.0,
+            ], [
+                -0.77043974, 0.14373614, -0.6210978, 0.0,
+                0.637035, 0.13586378, -0.75876695, 0.0,
+                -0.024677532, -0.98024535, -0.1962398, 0.0,
+                -0.48071152, -0.9316926, -0.1056232, 1.0,
+            ]),
+        ];
+        for (pitch, inverse_height, attack, right, left) in two {
+            let arms = map_arm_poses(MapHold::TwoHanded, false, pitch, inverse_height, attack);
+            assert_eq!(arms.len(), 2, "both arms under a two-handed map");
+            assert_eq!((arms[0].0, arms[1].0), (false, true), "right, then left");
+            near(arms[0].1, right, &format!("two right {pitch}"));
+            near(arms[1].1, left, &format!("two left {pitch}"));
+        }
+    }
+    #[test]
     fn ranged_draw_uses_native_charge_curves_and_caps() {
         for (ticks, stretch) in [
             (0.0, 1.0),

crates/horizon-client/src/game/advancements.rs

@@ -588,10 +588,17 @@ impl Game<'_> {
                             .announced
                             .push(Text::translate(key, &[player, name]));
                     }
-                    None => self.system_message(Text::translate(
-                        key,
-                        &[Text::literal(super::chat::PLAYER_NAME), name],
-                    )),
+                    None => {
+                        let text = Text::translate(key, &[self.player_display_text(), name]);
+                        // The guests hear of the host's advancement too.
+                        if let Some(host) = &self.lan {
+                            host.hub
+                                .system_message(horizon_client::lan::data::component_nbt(
+                                    &text.component(),
+                                ));
+                        }
+                        self.system_message(text);
+                    }
                 }
             }
         }
@@ -1366,6 +1373,55 @@ impl Game<'_> {
             adv::conditions(&c["player"], &pctx, w)
         });
     }
+    /// `RecipeCraftedTrigger`: the recipe and the stacks that went into it
+    /// (`ServerPlayer.triggerRecipeCrafted`); an empty slot is air.
+    pub(super) fn trigger_recipe_crafted(
+        &mut self,
+        recipe: &str,
+        ingredients: &[Option<ItemStack>],
+    ) {
+        let me = self.player_entity();
+        let used: Vec<ItemView> = ingredients
+            .iter()
+            .map(|s| {
+                s.as_ref().map_or_else(
+                    || ItemView {
+                        id: "minecraft:air".to_owned(),
+                        ..Default::default()
+                    },
+                    item_view,
+                )
+            })
+            .collect();
+        let recipe = recipe.to_owned();
+        self.trigger("minecraft:recipe_crafted", move |c, w| {
+            let pctx = adv::Entities {
+                this: Some(&me),
+                origin: me.position,
+                tool: None,
+                block_pos: None,
+            };
+            adv::conditions(&c["player"], &pctx, w)
+                && adv::id_matches(&c["recipes"], "recipe", &recipe, w)
+                && adv::recipe_ingredients(&c["ingredients"], &used, w)
+        });
+    }
+    /// `LootTableTrigger`: a container's loot table unpacked for this player
+    /// (`RandomizableContainer.unpackLootTable`).
+    pub(super) fn trigger_loot_table(&mut self, table: &str) {
+        let me = self.player_entity();
+        let table = table.to_owned();
+        self.trigger("minecraft:player_generates_container_loot", move |c, w| {
+            let pctx = adv::Entities {
+                this: Some(&me),
+                origin: me.position,
+                tool: None,
+                block_pos: None,
+            };
+            adv::conditions(&c["player"], &pctx, w)
+                && adv::id_matches(&c["loot_tables"], "loot_table", &table, w)
+        });
+    }
     /// `BredAnimalsTrigger`.
     pub(super) fn trigger_bred(
         &mut self,
@@ -1493,7 +1549,7 @@ impl Game<'_> {
             .iter()
             .filter_map(|t| t.slot)
             .chain(packs)
-            .fold(0, |used, slot| used | 1 << slot)
+            .fold(self.tutorial_toast_slots(), |used, slot| used | 1 << slot)
     }
     /// The `AdvancementToast` or `RecipeToast` at `index` in its slot at `y`.
     fn draw_toast(&mut self, batch: &mut HudBatch, index: usize, y: f32, multiplier: f64) {

crates/horizon-client/src/game/agent.rs

@@ -536,7 +536,9 @@ impl Game<'_> {
             title
                 .recent_worlds()
                 .iter()
-                .map(|w| json!({ "folder": w.folder, "name": w.name, "creative": w.creative }))
+                .map(
+                    |w| json!({ "folder": w.folder, "name": w.name, "creative": w.game_mode == 1 }),
+                )
                 .collect::<Vec<_>>()
         };
         match &title.mode {
@@ -546,7 +548,7 @@ impl Game<'_> {
                 selected,
             } => json!({
                 "mode": "select-world",
-                "worlds": list.iter().map(|w| json!({ "folder": w.folder, "name": w.name, "creative": w.creative })).collect::<Vec<_>>(),
+                "worlds": list.iter().map(|w| json!({ "folder": w.folder, "name": w.name, "creative": w.game_mode == 1 })).collect::<Vec<_>>(),
                 "selected": selected,
             }),
             Mode::Create {
@@ -564,7 +566,7 @@ impl Game<'_> {
                 "hardcore": options.hardcore,
                 "difficulty": horizon_client::title::DIFFICULTIES[options.difficulty()],
                 "allow_commands": options.commands(*creative),
-                "superflat": options.flat,
+                "world_type": options.world_type.id(),
                 "generate_structures": options.structures,
                 "bonus_chest": options.bonus_chest(),
             }),
@@ -577,7 +579,7 @@ impl Game<'_> {
             } => json!({
                 "mode": "customize-flat",
                 "fields": { "name": name, "seed": seed },
-                "superflat": options.flat,
+                "superflat": options.world_type == horizon_client::save::WorldPreset::Flat,
                 "biome": flat.settings().biome,
                 "layers": flat.settings().layers.iter().map(|layer| json!({
                     "block": layer.block,
@@ -1452,7 +1454,15 @@ impl Game<'_> {
                 self.playing()?;
                 let all = a.pos.first() == Some(&"all");
                 let before = self.held().map(|s| self.stack_value(s));
-                self.drop_held(all);
+                if self.remote.is_some() {
+                    // As Q does on a server (and on the single-player server
+                    // thread): the server throws the stack, the client predicts it.
+                    if !self.spectator() {
+                        self.remote_drop(all);
+                    }
+                } else {
+                    self.drop_held(all);
+                }
                 ok(
                     json!({ "ok": true, "dropped_from": before, "held": self.held().map(|s| self.stack_value(s)) }),
                 )

crates/horizon-client/src/game/allays.rs

@@ -219,7 +219,7 @@ impl Game<'_> {
         let holds = m.extra.main_hand.is_some();
         if !holds && !item.is_empty() {
             let m = &mut self.mobs[index];
-            m.extra.main_hand = Some(item.into());
+            m.extra.set_main_hand(Some(item.into()));
             m.extra.tame = true;
             // `Allay.mobInteract` remembers LIKED_PLAYER by UUID.
             m.extra.owner = Some(acting);

crates/horizon-client/src/game/armor_stands.rs

@@ -616,9 +616,6 @@ impl Game<'_> {
         };
         for a in &self.armor_stands {
             let entity_start = out.len();
-            if a.invisible {
-                continue;
-            }
             // ArmorStand.shouldRenderAtSqrDistance: 256 times the box's mean
             // edge (4 for a marker's empty box), whatever the entity distance.
             // LivingEntityRenderer grows the culling box by 0.5 for a dragon head.
@@ -690,16 +687,20 @@ impl Game<'_> {
                 a.position.z.floor() as i32,
             );
             let packed = (u32::from(light >> 4) * 16) | ((u32::from(light & 15) * 16) << 8);
-            horizon_client::mobs::render::draw(
-                model,
-                base,
-                &poses,
-                wood,
-                0xFFFF_FFFF,
-                packed,
-                0,
-                out,
-            );
+            // LivingEntityRenderer.submit: an invisible stand has no body render type, but its
+            // layers (held items, custom head, armour) are submitted all the same.
+            if !a.invisible {
+                horizon_client::mobs::render::draw(
+                    model,
+                    base,
+                    &poses,
+                    wood,
+                    0xFFFF_FFFF,
+                    packed,
+                    0,
+                    out,
+                );
+            }
             self.armor_stand_items(a, model, base, &posed, packed, out);
             // HumanoidArmorLayer: head, chest, legs, feet.
             for (slot, layer) in [

crates/horizon-client/src/game/beacon.rs

@@ -105,10 +105,28 @@ impl Game<'_> {
         let Some(BlockEntity::Beacon(mut b)) = self.world.block_entities.take(&key) else {
             return;
         };
-        self.tick_beacon(key, &mut b);
+        self.tick_beacon(key, &mut b, false);
         self.world.block_entities.put(key, BlockEntity::Beacon(b));
     }
-    fn tick_beacon(&mut self, (x, y, z): (i32, i32, i32), b: &mut Beacon) {
+    /// `ClientLevel.tickBlockEntities` for beacons: a server's chunk data
+    /// carries no beam sections, so the client builds them too; effects,
+    /// sounds and the advancement stay with the server.
+    pub(super) fn client_tick_beacons(&mut self) {
+        let keys: Vec<_> = self
+            .world
+            .block_entities
+            .iter()
+            .filter_map(|(k, e)| matches!(e, BlockEntity::Beacon(_)).then_some(*k))
+            .collect();
+        for key in keys {
+            let Some(BlockEntity::Beacon(mut b)) = self.world.block_entities.take(&key) else {
+                continue;
+            };
+            self.tick_beacon(key, &mut b, true);
+            self.world.block_entities.put(key, BlockEntity::Beacon(b));
+        }
+    }
+    fn tick_beacon(&mut self, (x, y, z): (i32, i32, i32), b: &mut Beacon, client: bool) {
         let mut check = if b.last_check_y < y {
             b.checking.clear();
             b.last_check_y = y - 1;
@@ -153,7 +171,7 @@ impl Game<'_> {
             if !b.sections.is_empty() {
                 b.levels = self.beacon_base(x, y, z);
             }
-            if b.levels > 0 && !b.sections.is_empty() {
+            if !client && b.levels > 0 && !b.sections.is_empty() {
                 self.beacon_effects([x, y, z], b);
                 self.beacon_sound([x, y, z], "minecraft:block.beacon.ambient");
             }
@@ -163,10 +181,12 @@ impl Game<'_> {
             b.sections = std::mem::take(&mut b.checking);
             let (was, is) = (previous > 0, b.levels > 0);
             if !was && is {
-                self.beacon_sound([x, y, z], "minecraft:block.beacon.activate");
-                let levels = b.levels;
-                self.for_each_player(|g| g.beacon_constructed([x, y, z], levels));
-            } else if was && !is {
+                if !client {
+                    self.beacon_sound([x, y, z], "minecraft:block.beacon.activate");
+                    let levels = b.levels;
+                    self.for_each_player(|g| g.beacon_constructed([x, y, z], levels));
+                }
+            } else if was && !is && !client {
                 self.beacon_sound([x, y, z], "minecraft:block.beacon.deactivate");
             }
         }
@@ -551,7 +571,12 @@ impl Game<'_> {
         }
     }
     /// `BeaconRenderer`: each section's rotating solid beam and its glow.
-    pub(super) fn beacon_geometry(&self, camera: glam::DVec3, alpha: f64, out: &mut Vec<Vertex>) {
+    pub(super) fn beacon_geometry(
+        &mut self,
+        camera: glam::DVec3,
+        alpha: f64,
+        out: &mut Vec<Vertex>,
+    ) {
         let Some(s) = self
             .gui
             .atlas
@@ -563,15 +588,28 @@ impl Game<'_> {
         };
         let time = (self.world.game_time.rem_euclid(40)) as f32 + alpha as f32;
         let scoping = self.scoping();
-        let view = f64::from(self.settings.render_distance * 16);
-        for (k, e) in &self.world.block_entities {
-            let BlockEntity::Beacon(b) = e else { continue };
-            // `getBeamSections` is empty while Levels is 0.
-            if b.levels == 0 || b.sections.is_empty() {
-                continue;
+        // `BeaconRenderer.shouldRender` culls at the render distance; far
+        // terrain extends that to its own distance.
+        let view = f64::from(self.terrain_distance() * 16);
+        let world = &self.world;
+        if self.lod.is_some() {
+            // The beam stays after its chunk unloads; once the chunk is back,
+            // its block entity decides whether the beam is still there.
+            self.far_beacons.retain(|&pos, _| {
+                let (x, _, z) = pos;
+                !world.chunks.contains_key(&(x >> 4, z >> 4))
+                    || world.block_entities.get(&pos).and_then(beam).is_some()
+            });
+        } else {
+            self.far_beacons.clear();
+        }
+        for (k, e) in &world.block_entities {
+            if let Some(sections) = beam(e) {
+                self.far_beacons.insert(*k, sections.to_vec());
             }
+        }
+        for (k, sections) in &self.far_beacons {
             let base = glam::DVec3::new(f64::from(k.0) + 0.5, f64::from(k.1), f64::from(k.2) + 0.5);
-            // `BeaconRenderer.shouldRender`: horizontal distance under render distance × 16.
             let offset = base - camera;
             let horizontal = glam::DVec2::new(offset.x, offset.z).length();
             if horizontal >= view {
@@ -586,14 +624,30 @@ impl Game<'_> {
             let origin = (glam::DVec3::new(f64::from(k.0), f64::from(k.1), f64::from(k.2))
                 - camera)
                 .as_vec3();
-            horizon_client::block_entity_render::beacon_beam(
-                origin,
-                &b.sections,
-                time,
-                scale,
-                s,
-                out,
-            );
+            horizon_client::block_entity_render::beacon_beam(origin, sections, time, scale, s, out);
         }
     }
 }
+/// The beam sections of an active beacon (`BeaconRenderer` draws no beam for
+/// a beacon without a pyramid or with all sections cleared).
+fn beam(e: &BlockEntity) -> Option<&[(u32, i32)]> {
+    match e {
+        BlockEntity::Beacon(b) if b.levels > 0 && !b.sections.is_empty() => Some(&b.sections),
+        _ => None,
+    }
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn only_active_beacons_have_beams() {
+        let mut b = Beacon::default();
+        assert!(beam(&BlockEntity::Beacon(Box::new(b.clone()))).is_none());
+        b.levels = 1;
+        b.sections.push((0xFFFFFF, 10));
+        assert_eq!(
+            beam(&BlockEntity::Beacon(Box::new(b))),
+            Some(&[(0xFFFFFF, 10)][..])
+        );
+    }
+}

crates/horizon-client/src/game/brush.rs

@@ -142,9 +142,11 @@ impl Game<'_> {
         let Some(mut tag) = spill::saved_entity(&self.world, pos) else {
             return;
         };
-        if tag.get("LootTable").is_none() {
+        let Some(horizon_world::nbt::Tag::String(table)) = tag.get("LootTable") else {
             return;
-        }
+        };
+        let table = table.to_string_lossy();
+        self.trigger_loot_table(&table);
         let loot = horizon_client::structure_blocks::loot_data(&self.options.resources);
         decorated_pot::unpack_loot(
             &mut tag,

crates/horizon-client/src/game/bundles.rs

@@ -16,6 +16,15 @@ pub(super) struct BundleMouse {
     hovered: Option<usize>,
 }
 
+/// Whether `screen` is an `AbstractContainerScreen`, whose `mouseScrolled` first offers
+/// the wheel to the hovered slot's `ItemSlotMouseAction`s (the bundle's), and whose
+/// `onStopHovering` clears the selection: the inventory and container menus, and
+/// `CreativeModeInventoryScreen`, which scrolls its items only when no bundle took
+/// the wheel.
+pub(super) fn takes_bundle_wheel(screen: Screen) -> bool {
+    matches!(screen, Screen::Inventory | Screen::Creative)
+}
+
 impl Game<'_> {
     /// A slot a bundle can be selected in: the player's inventory, the off hand and a
     /// container's own slots. A server only knows these in the inventory and chest-like menus.
@@ -89,7 +98,7 @@ impl Game<'_> {
     /// `AbstractContainerScreen.onStopHovering` (and `onClose`): leaving a slot, or the
     /// screen, clears the bundle's selection.
     pub(super) fn tick_bundle_hover(&mut self) {
-        let now = if self.screen == Screen::Inventory {
+        let now = if takes_bundle_wheel(self.screen) {
             self.inventory_target().0
         } else {
             None
@@ -101,3 +110,24 @@ impl Game<'_> {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// `CreativeModeInventoryScreen.mouseScrolled` calls `AbstractContainerScreen`'s
+    /// first: a bundle under the cursor takes the wheel there too (#3211).
+    #[test]
+    fn container_screens_offer_the_wheel_to_bundles() {
+        assert!(takes_bundle_wheel(Screen::Inventory));
+        assert!(takes_bundle_wheel(Screen::Creative));
+        for screen in [
+            Screen::Playing,
+            Screen::Chat,
+            Screen::Paused,
+            Screen::Options,
+        ] {
+            assert!(!takes_bundle_wheel(screen));
+        }
+    }
+}

crates/horizon-client/src/game/chat.rs

@@ -148,7 +148,7 @@ fn resource_ids(root: &Path) -> Arc<ResourceIds> {
         recipes: ids_under(&data.join("recipe"), "json"),
         damage_types: ids_under(&data.join("damage_type"), "json"),
         loot_tables: ids_under(&data.join("loot_table"), "json"),
-        templates: ids_under(&root.join("worldgen/structure/minecraft"), "nbt"),
+        templates: templates_under(&root.join("worldgen/structure")),
     });
     cache.push((root.to_owned(), ids.clone()));
     ids
@@ -156,6 +156,26 @@ fn resource_ids(root: &Path) -> Arc<ResourceIds> {
 
 /// The `minecraft:` ids of the `extension` files under `root`, sorted.
 fn ids_under(root: &Path, extension: &str) -> Vec<String> {
+    ids_in(root, extension, "minecraft")
+}
+
+/// The templates of every namespace folder under `root` (vanilla's and the
+/// content mods'), as `namespace:path`, sorted.
+fn templates_under(root: &Path) -> Vec<String> {
+    let Ok(namespaces) = std::fs::read_dir(root) else {
+        return Vec::new();
+    };
+    let mut out: Vec<String> = namespaces
+        .flatten()
+        .filter(|e| e.path().is_dir())
+        .flat_map(|e| ids_in(&e.path(), "nbt", &e.file_name().to_string_lossy()))
+        .collect();
+    out.sort();
+    out
+}
+
+/// The `namespace:` ids of the `extension` files under `root`, sorted.
+fn ids_in(root: &Path, extension: &str, namespace: &str) -> Vec<String> {
     let mut out = Vec::new();
     let mut stack = vec![root.to_owned()];
     while let Some(dir) = stack.pop() {
@@ -175,7 +195,7 @@ fn ids_under(root: &Path, extension: &str) -> Vec<String> {
                 && let Ok(rel) = path.strip_prefix(root)
             {
                 out.push(format!(
-                    "minecraft:{}",
+                    "{namespace}:{}",
                     rel.with_extension("").to_string_lossy().replace('\\', "/")
                 ));
             }
@@ -427,9 +447,21 @@ impl Game<'_> {
             .map(|(k, _)| k.clone())
             .collect();
     }
-    /// The block the player is looking at, for coordinate suggestions.
+    /// The block the player is looking at, for coordinate suggestions, and
+    /// the entity, for entity arguments (ClientSuggestionProvider).
+    /// `ClientSuggestionProvider.getRelevantCoordinates` and
+    /// `getAbsoluteCoordinates` read `Minecraft.hitResult` only when it is a
+    /// block: an entity in front of the block leaves the `~` defaults.
     fn refresh_dynamic_registries(&mut self) {
-        self.ui.registries.target_block = self.pick().map(|h| h.pos);
+        let hit = if self.pick_entity_hit().is_some() {
+            None
+        } else {
+            self.pick()
+        };
+        self.ui.registries.target_block = hit.as_ref().map(|h| h.pos);
+        self.ui.registries.target_point =
+            hit.map(|h| h.point.map(horizon_client::java_text::format_fixed2));
+        self.ui.registries.selected_entities = self.crosshair_entity_uuid().into_iter().collect();
         // ClientPacketListener.getOnlinePlayerNames on a server.
         if let Some(names) = self.remote_online_names() {
             self.ui.registries.players = names;
@@ -639,7 +671,7 @@ impl Game<'_> {
             ChatAction::None => {
                 // charTyped: the text the key typed.
                 if let Some(text) = typed_text
-                    && !ctrl
+                    && self.types_text()
                 {
                     screen.type_text(&m, &c, text);
                 }
@@ -1138,9 +1170,19 @@ impl Game<'_> {
             None => self.combat_death_message(),
         };
         self.ui.death_text = Some(message.clone());
-        // ServerPlayer.die: a team that hides death messages keeps it out of
-        // the dying player's own chat (the death screen still shows it).
-        if horizon_client::scoreboard::own_death_message_shown(self.player_team()) {
+        // ServerPlayer.die: the team's death message visibility decides who
+        // hears it, the dying player's own chat included (the death screen
+        // still shows it).
+        let board = &self.score.board;
+        if let Some(host) = &self.lan {
+            host.hub.system_message_to(
+                horizon_client::lan::data::component_nbt(&message.component()),
+                |other| {
+                    horizon_client::scoreboard::death_message_reaches(board, PLAYER_NAME, other)
+                },
+            );
+        }
+        if horizon_client::scoreboard::death_message_reaches(board, PLAYER_NAME, PLAYER_NAME) {
             self.system_message(message);
         }
     }
@@ -1171,6 +1213,7 @@ impl Game<'_> {
         };
         let message = match result {
             Ok(_) => {
+                log::info!("Saved screenshot to {}", path.display());
                 let name = path.file_name().unwrap_or_default().to_string_lossy();
                 let link = Text::styled(
                     name,
@@ -1195,24 +1238,10 @@ impl Game<'_> {
         );
     }
 }
-/// `yyyy-MM-dd_HH.mm.ss[_n].png` (Util.getFilenameFormattedDateTime, local time
-/// approximated as UTC).
+/// `yyyy-MM-dd_HH.mm.ss[_n].png` (Util.getFilenameFormattedDateTime, in local time).
 pub fn screenshot_name(dir: &std::path::Path) -> String {
-    let secs = std::time::SystemTime::now()
-        .duration_since(std::time::UNIX_EPOCH)
-        .map_or(0, |d| d.as_secs());
-    let days = (secs / 86400) as i64;
-    let (h, m, s) = ((secs % 86400) / 3600, (secs % 3600) / 60, secs % 60);
-    let z = days + 719_468;
-    let era = z.div_euclid(146_097);
-    let doe = z - era * 146_097;
-    let yoe = (doe - doe / 1460 + doe / 36524 - doe / 146_096) / 365;
-    let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
-    let mp = (5 * doy + 2) / 153;
-    let d = doy - (153 * mp + 2) / 5 + 1;
-    let mo = if mp < 10 { mp + 3 } else { mp - 9 };
-    let y = yoe + era * 400 + i64::from(mo <= 2);
-    let base = format!("{y}-{mo:02}-{d:02}_{h:02}.{m:02}.{s:02}");
+    // Util.getFilenameFormattedDateTime: the local date and time.
+    let base = chrono::Local::now().format("%Y-%m-%d_%H.%M.%S").to_string();
     let mut n = 1;
     loop {
         let name = if n == 1 {

crates/horizon-client/src/game/clipboard.rs

@@ -27,6 +27,22 @@ impl Game<'_> {
             m.alt_key() || held([KeyCode::AltLeft, KeyCode::AltRight]),
         )
     }
+    /// Whether the held keys let a key's text through to the focused field
+    /// (`clipboard::types_text`): not with the edit modifier, unless it is
+    /// part of AltGr.
+    pub(super) fn types_text(&self) -> bool {
+        let held = |keys: [KeyCode; 2]| keys.iter().any(|k| self.physical_keys.contains(k));
+        let edit = if cfg!(target_os = "macos") {
+            held([KeyCode::SuperLeft, KeyCode::SuperRight])
+        } else {
+            held([KeyCode::ControlLeft, KeyCode::ControlRight])
+        };
+        clipboard::types_text(
+            edit,
+            held([KeyCode::AltLeft, KeyCode::AltRight]),
+            clipboard::ALTGR_IS_CTRL_ALT,
+        )
+    }
     /// A shortcut in an append-only field limited to `max_chars` characters
     /// (an `EditBox` with `setMaxLength`). True when the value changed.
     pub(super) fn append_shortcut(

crates/horizon-client/src/game/combat.rs

@@ -304,6 +304,16 @@ impl Game<'_> {
             None
         }
     }
+    /// The display component of a custom-named held stack.
+    fn mob_main_hand_name(&self, id: u32) -> Option<Text> {
+        let m = self.mobs.iter().find(|m| m.id == id)?;
+        let mut stack = m.extra.main_hand_stack()?.clone();
+        stack.custom_name()?;
+        if let Some(g) = horizon_client::mobs::gear::gear(m) {
+            stack.data_mut().enchantments = g.slots[horizon_client::mobs::gear::MAIN].clone();
+        }
+        Some(self.stack_display_name(&stack))
+    }
     /// `CombatTracker.getDeathMessage`.
     pub(super) fn combat_death_message(&mut self) -> Text {
         self.combat_death_message_for(Text::literal(PLAYER_NAME))
@@ -357,8 +367,16 @@ impl Game<'_> {
         }
         // `getLocalizedDeathMessage`: the causing entity's name, or the
         // direct entity's when nothing caused the damage.
-        if let Some((_, name)) = killer {
-            return Text::translate(&key, &[me, name]);
+        if let Some((id, name)) = killer {
+            // DamageSource.getLocalizedDeathMessage: the cause's item with a
+            // custom name gets the `<id>.item` message.
+            let (key, args) = horizon_client::scoreboard::death_message_args(
+                &key,
+                &me,
+                &name,
+                self.mob_main_hand_name(id).as_ref(),
+            );
+            return Text::translate(&key, &args);
         }
         if let Some(name) = direct {
             return Text::translate(&key, &[me, name]);

crates/horizon-client/src/game/command_blocks.rs

@@ -574,12 +574,13 @@ impl Game<'_> {
         let ctrl = self.keys.contains(&KeyCode::ControlLeft);
         let shift = self.keys.contains(&KeyCode::ShiftLeft);
         let shortcut = self.edit_shortcut(event);
+        let types_text = self.types_text();
         let Some(s) = self.command_block_screen.as_mut() else {
             return;
         };
         if let Some(shortcut) = shortcut {
             s.command.shortcut(shortcut, &mut self.clipboard);
-        } else if !s.command.key(key, ctrl, shift) && !ctrl {
+        } else if !s.command.key(key, ctrl, shift) && types_text {
             self.command_block_type(event.text.as_deref().unwrap_or(""));
         }
     }

crates/horizon-client/src/game/commands.rs

@@ -925,24 +925,7 @@ impl Game<'_> {
                 Ok(1)
             }
             "say" | "me" | "msg" => self.cmd_say(id, ctx),
-            "list" => {
-                let names = if ctx.has("uuids") {
-                    Text::translate(
-                        "commands.list.nameAndId",
-                        &[
-                            Text::literal(PLAYER_NAME),
-                            Text::literal(self.player_uuid_string()),
-                        ],
-                    )
-                } else {
-                    Text::literal(PLAYER_NAME)
-                };
-                self.system_message(Text::translate(
-                    "commands.list.players",
-                    &[Text::literal("1"), Text::literal("8"), names],
-                ));
-                Ok(1)
-            }
+            "list" => self.cmd_list(ctx),
             _ => Err(err("command.failed", &[])),
         }
     }
@@ -2089,6 +2072,49 @@ impl Game<'_> {
         self.world.modified.insert((pos[0] >> 4, pos[2] >> 4));
         true
     }
+    /// `RandomizableContainer.unpackLootTable` for a player who opens a
+    /// container: a roll the container still holds fires
+    /// `player_generates_container_loot` for its table, and from then on the
+    /// container saves its items, not the table.
+    pub(super) fn unpack_opened_loot(&mut self, key: (i32, i32, i32), name: &str) {
+        let Some(rolled) = self
+            .world
+            .chunks
+            .get(&(key.0 >> 4, key.2 >> 4))
+            .and_then(|c| c.saved.as_ref())
+            .and_then(|s| s.rolled_loot.iter().find(|r| r.pos == key))
+            .cloned()
+        else {
+            return;
+        };
+        // The roll is still there only while the container holds exactly its items.
+        let still_rolled = self
+            .world
+            .block_entities
+            .get_mut(&key)
+            .is_some_and(|entity| {
+                let mut tag = horizon_client::save::encode_block_entity(key, entity, name);
+                match &mut tag {
+                    horizon_world::nbt::Tag::Compound(map) => rolled.restore(map),
+                    _ => false,
+                }
+            });
+        if still_rolled {
+            self.trigger_loot_table(&rolled.table);
+        }
+        let Some(chunk) = self.world.chunks.get_mut(&(key.0 >> 4, key.2 >> 4)) else {
+            return;
+        };
+        let chunk = std::sync::Arc::make_mut(chunk);
+        let mut extras = chunk
+            .saved
+            .take()
+            .map(std::sync::Arc::unwrap_or_clone)
+            .unwrap_or_default();
+        extras.rolled_loot.retain(|r| r.pos != key);
+        chunk.saved = Some(std::sync::Arc::new(extras));
+        self.world.modified.insert((key.0 >> 4, key.2 >> 4));
+    }
     /// RandomizableContainer.tryLoadLootTable for a tag a command gives a
     /// container (`setblock`, `data`): an empty container with a `LootTable`
     /// is rolled now, as a loaded chunk's are (`save::roll_loaded_loot`), and
@@ -3099,6 +3125,63 @@ impl Game<'_> {
         }
         out
     }
+    /// ListPlayersCommand: every online player, the host of a hosted world
+    /// first and then the guests in join order, with the count and the max.
+    fn cmd_list(&mut self, ctx: &Context) -> R<i32> {
+        // A single-player owner is a placed guest of the in-process server, so
+        // it is the host and needs no entry of its own.
+        let owner_listed = self
+            .lan
+            .as_ref()
+            .is_some_and(|h| h.hub.singleplayer_owner.is_some());
+        // The host is online unless this is a dedicated server, which has none.
+        let host = (self.options.dedicated.is_none() && !owner_listed).then(|| match &self.lan {
+            Some(h) => (h.host_uuid, h.host_name.clone()),
+            None => (self.player_uuid(), PLAYER_NAME.to_owned()),
+        });
+        let guests = self
+            .lan
+            .iter()
+            .flat_map(|h| h.hub.guests.iter())
+            .filter(|g| g.placed)
+            .map(|g| (g.uuid, g.name.clone()));
+        let players: Vec<(u128, String)> = host.into_iter().chain(guests).collect();
+        let max = self
+            .lan
+            .as_ref()
+            .map_or(horizon_client::lan::MAX_PLAYERS, |h| {
+                h.hub.lan.shared.max_players()
+            });
+        let uuids = ctx.has("uuids");
+        let mut names = Text::empty();
+        for (k, (uuid, name)) in players.iter().enumerate() {
+            if k > 0 {
+                // ComponentUtils.formatList: gray commas.
+                names.push(Text::colored(", ", text::GRAY));
+            }
+            if uuids {
+                names.push(Text::translate(
+                    "commands.list.nameAndId",
+                    &[
+                        Text::literal(name.as_str()),
+                        Text::literal(horizon_protocol::crypto::uuid_string(*uuid)),
+                    ],
+                ));
+            } else {
+                names.push(self.player_text(name, *uuid));
+            }
+        }
+        let count = players.len();
+        self.system_message(Text::translate(
+            "commands.list.players",
+            &[
+                Text::literal(count.to_string()),
+                Text::literal(max.to_string()),
+                names,
+            ],
+        ));
+        Ok(count as i32)
+    }
     fn cmd_say(&mut self, id: &str, ctx: &Context) -> R<i32> {
         let raw = match ctx.get(if id == "me" { "action" } else { "message" }) {
             Some(Arg::Str(s)) => s.clone(),

crates/horizon-client/src/game/commands/extra.rs

@@ -1115,10 +1115,10 @@ impl Game<'_> {
     }
 }
 impl Game<'_> {
-    /// The player's profile id as `UUID.toString()`: the saved id, else the
-    /// offline id of the player's name.
-    pub(in crate::game) fn player_uuid_string(&self) -> String {
-        let id = self.level.player_uuid.map_or_else(
+    /// The player's profile id: the saved id, else the offline id of the
+    /// player's name.
+    pub(in crate::game) fn player_uuid(&self) -> u128 {
+        self.level.player_uuid.map_or_else(
             || horizon_protocol::crypto::offline_uuid(super::super::chat::PLAYER_NAME),
             |[a, b, c, d]| {
                 (u128::from(a as u32) << 96)
@@ -1126,15 +1126,6 @@ impl Game<'_> {
                     | (u128::from(c as u32) << 32)
                     | u128::from(d as u32)
             },
-        );
-        let h = format!("{id:032x}");
-        format!(
-            "{}-{}-{}-{}-{}",
-            &h[..8],
-            &h[8..12],
-            &h[12..16],
-            &h[16..20],
-            &h[20..]
         )
     }
 }

crates/horizon-client/src/game/commands/items.rs

@@ -235,9 +235,9 @@ impl Game<'_> {
                 let Some(m) = self.mobs.iter_mut().find(|m| m.id == *id) else {
                     return false;
                 };
-                let item = stack.map(|s| s.item);
+                let item = stack.as_ref().map(|s| s.item.clone());
                 match *key {
-                    "mainhand" => m.extra.main_hand = item,
+                    "mainhand" => m.extra.set_main_hand_stack(stack),
                     "offhand" => m.extra.off_hand = item,
                     "head" | "body" => m.extra.head = item,
                     "chest" => m.extra.chest = item,

crates/horizon-client/src/game/commands/players.rs

@@ -73,7 +73,7 @@ impl Game<'_> {
 
     /// `EntitySelector.findEntities` with a UUID: the player with it, else
     /// the entity.
-    pub(super) fn target_by_uuid(&self, uuid: u128) -> Option<Target> {
+    pub(in crate::game) fn target_by_uuid(&self, uuid: u128) -> Option<Target> {
         let own = self.lan_acting_uuid.or_else(|| {
             self.level.player_uuid.map(|[a, b, c, d]| {
                 (u128::from(a as u32) << 96)

crates/horizon-client/src/game/commands/text_commands.rs

@@ -6,7 +6,7 @@ use horizon_protocol::packets::play::{self, Clientbound as C};
 impl Game<'_> {
     /// ComponentArgument with selectors resolved for the source
     /// (ComponentUtils.updateForEntity: names joined by ", ").
-    fn component_arg(&mut self, ctx: &Context, name: &str) -> R<Text> {
+    pub(in crate::game) fn component_arg(&mut self, ctx: &Context, name: &str) -> R<Text> {
         let Some(Arg::Str(json)) = ctx.get(name) else {
             return Ok(Text::empty());
         };

crates/horizon-client/src/game/commands/world_cmds.rs

@@ -124,6 +124,21 @@ impl Game<'_> {
             "freeze" => DamageKind::Freeze,
             "in_wall" => DamageKind::InWall,
             "thorns" => DamageKind::Thorns,
+            "cramming" => DamageKind::Cramming,
+            "falling_anvil" => DamageKind::FallingAnvil,
+            "falling_block" => DamageKind::FallingBlock,
+            "fireworks" => DamageKind::Fireworks,
+            "generic_kill" => DamageKind::GenericKill,
+            "lightning_bolt" => DamageKind::LightningBolt,
+            "out_of_world" => DamageKind::OutOfWorld,
+            "outside_border" => DamageKind::OutsideBorder,
+            "sonic_boom" => DamageKind::SonicBoom,
+            "spit" => DamageKind::Spit,
+            "stalagmite" => DamageKind::Stalagmite,
+            "starve" => DamageKind::Starve,
+            "sulfur_cube_hot" => DamageKind::SulfurCubeHot,
+            "wind_charge" => DamageKind::WindCharge,
+            "wither" => DamageKind::Wither,
             _ => DamageKind::Generic,
         }
     }

crates/horizon-client/src/game/control.rs

@@ -361,7 +361,8 @@ impl Game<'_> {
                                 if action != "up" {
                                     self.play_mouse(button, true)?;
                                 }
-                                if action != "down" {
+                                // A repeat keeps the key held, as the window's.
+                                if action == "up" || action == "tap" {
                                     self.play_mouse(button, false)?;
                                 }
                             }

crates/horizon-client/src/game/creatures.rs

@@ -2,7 +2,7 @@
 //! chunk-generation spawning (`NaturalSpawner`), mob events (attacks,
 //! breeding, conversions, drops), projectiles, player interactions
 //! (feeding, shearing, milking, spawn eggs, throwing) and rendering.
-use super::{Dim, Game, view_vector};
+use super::{Dim, Game, dispenser, view_vector};
 use horizon_assets::item_model::DisplayContext;
 use horizon_client::{
     Result,
@@ -857,7 +857,7 @@ impl Game<'_> {
         }
         self.score_entity_removed(m.id);
         self.raider_died(m, by_player);
-        self.villager_murdered(m, by_player);
+        self.villager_murdered(m, by_player, killer.flatten());
         let pos = [m.position.x, m.position.y + 0.5, m.position.z];
         self.drop_death_loot(&mut dying, by_player, consumed, pos);
         self.create_wither_rose(m);
@@ -1019,7 +1019,13 @@ impl Game<'_> {
                     } else {
                         from_loot(&stack)
                     };
-                    self.spawn_item(item, pos, [0.0, 0.2, 0.0], 10);
+                    // Every death drop is its own ItemEntity, and the drop
+                    // entity's own random (not the level's) gives it the
+                    // constructor's horizontal push (its motion otherwise
+                    // stays [0, 0.2, 0] and the drops land stacked at the
+                    // mob's centre, without disturbing the level random that
+                    // the orbs' merge ids and block ticks read next).
+                    self.spawn_item(item, pos, dispenser::new_item_motion(), 10);
                 }
                 drops::Drop::Orb(value) if !consumed => self.spawn_orbs(pos, value as u32),
                 drops::Drop::Orb(_) => {}
@@ -1125,7 +1131,9 @@ impl Game<'_> {
                 .loot_table(table, false, None, &mut self.world.random),
         };
         for d in stacks {
-            self.spawn_item(d, at, [0.0, 0.2, 0.0], 10);
+            // The ItemEntity constructor's motion, from the entity's own
+            // random (not the level's).
+            self.spawn_item(d, at, dispenser::new_item_motion(), 10);
         }
     }
     /// Adds a projectile, giving it an id from the entity counter
@@ -1469,7 +1477,11 @@ impl Game<'_> {
                         extra: None,
                     },
                     at,
-                    [0.0, 0.2, 0.0],
+                    // The ItemEntity constructor's motion, from the entity's
+                    // own random (not the level's), so spawnAtLocation drops
+                    // (a fox's berries, a panda's held food, a goat's horn)
+                    // land apart.
+                    dispenser::new_item_motion(),
                     10,
                 ),
                 MobEvent::DropGift { table, at } => {
@@ -1478,14 +1490,9 @@ impl Game<'_> {
                             .items()
                             .loot_table(table, false, None, &mut self.world.random);
                     for stack in stacks {
-                        // The ItemEntity constructor's random motion.
-                        let r = &mut self.world.random;
-                        let v = [
-                            r.next_double() * 0.2 - 0.1,
-                            0.2,
-                            r.next_double() * 0.2 - 0.1,
-                        ];
-                        self.spawn_item(stack, at, v, 10);
+                        // The ItemEntity constructor's motion, from the
+                        // entity's own random (not the level's).
+                        self.spawn_item(stack, at, dispenser::new_item_motion(), 10);
                     }
                 }
                 // `Level.setBlockAndUpdate`: neighbour and shape updates, so a crop
@@ -4877,6 +4884,17 @@ pub(super) fn damage_type(kind: horizon_client::mobs::DamageKind, player: bool)
         K::Freeze => "minecraft:freeze",
         K::OutOfWorld => "minecraft:out_of_world",
         K::Cramming => "minecraft:cramming",
+        K::FallingAnvil => "minecraft:falling_anvil",
+        K::Fireworks => "minecraft:fireworks",
+        K::GenericKill => "minecraft:generic_kill",
+        K::LightningBolt => "minecraft:lightning_bolt",
+        K::OutsideBorder => "minecraft:outside_border",
+        K::Spit => "minecraft:spit",
+        K::Stalagmite => "minecraft:stalagmite",
+        K::Starve => "minecraft:starve",
+        K::SulfurCubeHot => "minecraft:sulfur_cube_hot",
+        K::WindCharge => "minecraft:wind_charge",
+        K::Wither => "minecraft:wither",
     }
 }
 /// A Horizon item stack as a loot stack (id, count, damage, enchantments).

crates/horizon-client/src/game/dedicated.rs

@@ -26,12 +26,105 @@ use horizon_world::nbt::{JavaString, Tag};
 use std::{
     io::Write,
     path::PathBuf,
-    sync::{Arc, Mutex, OnceLock, mpsc},
+    sync::{
+        Arc, Mutex, OnceLock,
+        atomic::{AtomicBool, AtomicU64, Ordering},
+        mpsc,
+    },
     time::{Duration, Instant},
 };
 
 mod status;
 
+/// What the tick loop tells `ServerWatchdog`: when the tick in progress was
+/// due (`getNextTickTime`), how long a tick is, and whether the server runs.
+struct Watchdog {
+    base: Instant,
+    next_nanos: AtomicU64,
+    tick_nanos: AtomicU64,
+    running: AtomicBool,
+}
+
+impl Watchdog {
+    /// `DedicatedServer.initServer`: a thread that stops a server whose tick
+    /// runs `max_tick_time` ms past its due time; none when that is 0 or less.
+    fn start(max_tick_time: i64) -> Option<Arc<Self>> {
+        let max = Duration::from_millis(u64::try_from(max_tick_time).ok().filter(|m| *m > 0)?);
+        let watchdog = Arc::new(Self {
+            base: Instant::now(),
+            next_nanos: AtomicU64::new(0),
+            tick_nanos: AtomicU64::new(50_000_000),
+            running: AtomicBool::new(true),
+        });
+        let shared = watchdog.clone();
+        std::thread::Builder::new()
+            .name("Server Watchdog".into())
+            .spawn(move || shared.run(max))
+            .ok()?;
+        Some(watchdog)
+    }
+    /// The tick loop is about to run the tick due at `next`.
+    fn tick_due(&self, next: Instant, tick: Duration) {
+        let nanos = next.saturating_duration_since(self.base).as_nanos();
+        self.next_nanos
+            .store(u64::try_from(nanos).unwrap_or(u64::MAX), Ordering::Relaxed);
+        let tick = u64::try_from(tick.as_nanos()).unwrap_or(u64::MAX);
+        self.tick_nanos.store(tick, Ordering::Relaxed);
+    }
+    /// `ServerWatchdog.run`.
+    fn run(&self, max: Duration) {
+        let max = u64::try_from(max.as_nanos()).unwrap_or(u64::MAX);
+        while self.running.load(Ordering::Relaxed) {
+            let next = self.next_nanos.load(Ordering::Relaxed);
+            let now = u64::try_from(self.base.elapsed().as_nanos()).unwrap_or(u64::MAX);
+            let behind = now.saturating_sub(next);
+            if behind > max {
+                let took = format!("{:.2}", behind as f32 / 1e9);
+                let should = format!(
+                    "{:.2}",
+                    self.tick_nanos.load(Ordering::Relaxed) as f32 / 1e9
+                );
+                log_from(
+                    "Server Watchdog",
+                    "ERROR",
+                    &format!("A single server tick took {took} seconds (should be max {should})"),
+                );
+                log_from(
+                    "Server Watchdog",
+                    "ERROR",
+                    "Considering it to be crashed, server will forcibly shutdown.",
+                );
+                let message = format!(
+                    "ServerWatchdog detected that a single server tick took {took} seconds (should be max {should})"
+                );
+                match horizon_client::crash::report_watchdog(
+                    std::path::Path::new("."),
+                    "server",
+                    message,
+                ) {
+                    Some(path) => log_from(
+                        "Server Watchdog",
+                        "ERROR",
+                        &format!(
+                            "This crash report has been saved to: {}",
+                            path.canonicalize().unwrap_or(path).display()
+                        ),
+                    ),
+                    None => log_from(
+                        "Server Watchdog",
+                        "ERROR",
+                        "We were unable to save this crash report to disk.",
+                    ),
+                }
+                std::process::exit(1);
+            }
+            // Thread.sleep(nextTickTime + maxTickTime - now).
+            let wait = (next + max).saturating_sub(now).max(1_000_000);
+            std::thread::sleep(Duration::from_nanos(wait));
+        }
+    }
+}
+
 /// Double.toString for the magnitudes positions have (no exponent form
 /// between 1e-3 and 1e7).
 pub(super) fn java_double(v: f64) -> String {
@@ -298,15 +391,14 @@ impl Lists {
     }
 }
 
-/// The world presets of 26.3's `worldgen/world_preset`.
-const WORLD_PRESETS: [&str; 7] = [
-    "minecraft:normal",
-    "minecraft:flat",
-    "minecraft:large_biomes",
-    "minecraft:amplified",
-    "minecraft:single_biome_surface",
-    "minecraft:debug_all_block_states",
-    "minecraft:flat_all_dimensions",
+/// DedicatedServerProperties.LEGACY_PRESET_NAMES: the old `level-type`
+/// names, before the presets had their own ids.
+const LEGACY_PRESET_NAMES: [(&str, horizon_client::save::WorldPreset); 2] = [
+    ("default", horizon_client::save::WorldPreset::Normal),
+    (
+        "largebiomes",
+        horizon_client::save::WorldPreset::LargeBiomes,
+    ),
 ];
 
 /// Identifier.tryParse: `namespace:path`, or a path in `minecraft`.
@@ -323,11 +415,18 @@ impl Game<'_> {
     /// DedicatedServerProperties.createDimensions for a world that doesn't
     /// exist yet: `level-type`'s preset, a flat world's `generator-settings`
     /// and `generate-structures`, written before the world opens so that
-    /// streaming reads them. Horizon generates the normal and flat presets.
+    /// streaming reads them.
     fn write_world_gen(&self, dir: &std::path::Path, props: &ServerProperties) -> Result<()> {
         let level_type = &props.level_type;
         let preset = parse_identifier(level_type)
-            .filter(|id| WORLD_PRESETS.contains(&id.as_str()))
+            .as_deref()
+            .and_then(horizon_client::save::WorldPreset::of_id)
+            .or_else(|| {
+                LEGACY_PRESET_NAMES
+                    .iter()
+                    .find(|(name, _)| *name == level_type)
+                    .map(|(_, preset)| *preset)
+            })
             .unwrap_or_else(|| {
                 log_from(
                     "Worker-Main-1",
@@ -336,18 +435,9 @@ impl Game<'_> {
                         "Failed to parse level-type {level_type}, defaulting to minecraft:normal"
                     ),
                 );
-                "minecraft:normal".to_owned()
+                horizon_client::save::WorldPreset::Normal
             });
-        let flat = preset == "minecraft:flat";
-        if !flat && preset != "minecraft:normal" {
-            log_from(
-                "Worker-Main-1",
-                "WARN",
-                &format!(
-                    "Horizon doesn't generate the {preset} world preset yet: using minecraft:normal"
-                ),
-            );
-        }
+        let flat = preset == horizon_client::save::WorldPreset::Flat;
         let settings = if flat {
             let biomes = self.res.biomes();
             let (settings, errors) = horizon_client::flatgen::settings_from_json(
@@ -363,7 +453,7 @@ impl Game<'_> {
             None
         };
         let options = horizon_client::save::WorldGen {
-            flat,
+            preset,
             structures: props.generate_structures,
             bonus_chest: false,
         };
@@ -608,6 +698,7 @@ impl Game<'_> {
             motd: props.motd.clone(),
             max_players: props.max_players.max(0) as usize,
             compression_threshold: props.network_compression_threshold,
+            rate_limit: props.rate_limit,
             enable_status: props.enable_status,
             hide_online_players: props.hide_online_players,
             favicon,
@@ -704,8 +795,13 @@ impl Game<'_> {
         let pause_after = props.pause_when_empty_seconds * 20;
         let idle_timeout = props.player_idle_timeout;
         let mut next = Instant::now();
+        self.fns.permission = Some(props.function_permission_level.clamp(0, 4) as u8);
+        let watchdog = Watchdog::start(props.max_tick_time);
         while !state.stop {
             let tick_start = Instant::now();
+            if let Some(watchdog) = &watchdog {
+                watchdog.tick_due(next, self.clock.tick_duration());
+            }
             while let Ok(line) = state.console.try_recv() {
                 self.console_line(&mut state, &line);
             }
@@ -746,6 +842,9 @@ impl Game<'_> {
             state.ticked(Instant::now());
             self.wait_for_next_server_tick(&mut next, paused);
         }
+        if let Some(watchdog) = &watchdog {
+            watchdog.running.store(false, Ordering::Relaxed);
+        }
         self.stop_dedicated()
     }
 
@@ -1355,10 +1454,13 @@ impl Game<'_> {
     fn stop_dedicated(&mut self) -> Result<()> {
         log("INFO", "Stopping server");
         log("INFO", "Saving players");
-        if let Some(h) = self.lan.as_mut() {
-            for g in &h.hub.guests {
-                horizon_client::lan::playerdata::save(g, &self.world_root);
+        if let Some(host) = self.lan.take() {
+            for g in &host.hub.guests {
+                // The vehicle the guest rides, for the file that names it.
+                let vehicle = self.root_vehicle_uuid(g.vehicle);
+                horizon_client::lan::playerdata::save(g, &self.world_root, vehicle);
             }
+            self.lan = Some(host);
         }
         if let Some(h) = self.lan.as_ref() {
             for g in &h.hub.guests {

crates/horizon-client/src/game/dialogs.rs

@@ -8,7 +8,7 @@ use horizon_client::{
     Result,
     clipboard::EditShortcut,
     confirm_screen::Confirm,
-    dialog::{AfterAction, Click, Control, Dialog, InputValue},
+    dialog::{AfterAction, Body, Click, Control, Dialog, InputValue, Kind},
     dialog_screen::{BOX, Layout, Part, WARNING_SPRITES, waiting_button},
     hud::{HudBatch, rgba},
     text::Text,
@@ -26,6 +26,8 @@ struct Open {
     fields: Vec<Option<ui::EditBox>>,
     focus: Option<usize>,
     scroll: ui::Scroll,
+    /// The number range input whose slider is held.
+    dragging: Option<usize>,
 }
 
 /// The dialog screens a server can open.
@@ -38,6 +40,17 @@ pub(super) struct DialogState {
     warning: bool,
 }
 
+/// `CycleButton.cycleValue`: the next option (`delta` 1) or the one before
+/// it, wrapping.
+fn cycle(open: &mut Open, input: usize, delta: i32) {
+    let Control::SingleOption { options, .. } = &open.dialog.inputs[input].control else {
+        return;
+    };
+    if let Some(InputValue::Option(i)) = open.values.get_mut(input) {
+        *i = (*i as i32 + delta).rem_euclid(options.len().max(1) as i32) as usize;
+    }
+}
+
 fn warning_texts() -> (Text, Text, [Text; 2]) {
     let t = |key: &str| Text::translate(key, &[]);
     (
@@ -57,10 +70,35 @@ impl Game<'_> {
     /// `showDialog`: the dialog replaces an open one (and a waiting screen);
     /// under the warning screen, it is what Back returns to.
     pub(super) fn show_dialog(&mut self, tag: &Tag) {
-        let Some(dialog) = Dialog::parse(tag) else {
+        let Some(mut dialog) = Dialog::parse(tag) else {
             log::warn!("Horizon: failed to show dialog for data {tag:?}");
             return;
         };
+        if let Kind::DialogList { dialogs, .. } = &dialog.kind {
+            let entries = self.remote.as_ref().map(|r| {
+                let list = r.registries.registries.get("minecraft:dialog");
+                let by_id = |id: &str| {
+                    let name = if id.contains(':') {
+                        id.to_owned()
+                    } else {
+                        format!("minecraft:{id}")
+                    };
+                    list?.iter().find(|(n, _)| *n == name)?.1.clone()
+                };
+                let by_tag = |name: &str| {
+                    let name = if name.contains(':') {
+                        name.to_owned()
+                    } else {
+                        format!("minecraft:{name}")
+                    };
+                    let ids = r.registries.dialog_tags.get(&name).into_iter().flatten();
+                    ids.filter_map(|&i| list?.get(usize::try_from(i).ok()?)?.1.clone())
+                        .collect()
+                };
+                Dialog::list_entries(dialogs, &by_tag, &by_id)
+            });
+            dialog.set_list(&entries.unwrap_or_default());
+        }
         let values = dialog.inputs.iter().map(|i| i.control.initial()).collect();
         let fields = dialog
             .inputs
@@ -87,6 +125,7 @@ impl Game<'_> {
             fields,
             focus: None,
             scroll: ui::Scroll::default(),
+            dragging: None,
         });
         self.dialogs.waiting = None;
         self.capture(false);
@@ -123,6 +162,17 @@ impl Game<'_> {
     /// `DialogScreen.runAction`: the click event, then the screen the dialog's
     /// `after_action` leaves.
     fn run_dialog_action(&mut self, click: Option<Click>, after: AfterAction) -> Result<()> {
+        // defaultHandleClickEvent: an open_url never sets the screen itself, so
+        // the dialog stays unless the confirmation takes over (Web Links off,
+        // or Prompt on Links off, opens nothing or the browser behind it).
+        if let Some(Click::OpenUrl(url)) = &click
+            && !(self.settings.chat_links && self.settings.file.bool("chatLinksPrompt"))
+        {
+            if self.settings.chat_links {
+                super::packs::open_uri(url);
+            }
+            return Ok(());
+        }
         match after {
             AfterAction::None => {}
             AfterAction::Close => self.dialogs.open = None,
@@ -153,7 +203,11 @@ impl Game<'_> {
                 use horizon_client::clipboard::Clipboard;
                 self.clipboard.set(&value);
             }
-            Some(other) => log::info!("Horizon: dialog action {other:?} is not supported yet"),
+            // ConfirmLinkScreen over the screen the dialog leaves.
+            Some(Click::OpenUrl(url)) => self.click_url(url),
+            // Screen.insertText: the screen after the dialog takes no text.
+            Some(Click::SuggestCommand(_)) => {}
+            Some(other) => log::error!("Don't know how to handle {other:?}"),
             None => {}
         }
         if !self.dialog_open() {
@@ -262,7 +316,8 @@ impl Game<'_> {
         let Some(layout) = self.dialog_layout() else {
             return;
         };
-        let Some(open) = self.dialogs.open.as_mut() else {
+        // Out of `self` while it draws: an item body draws through `self`.
+        let Some(mut open) = self.dialogs.open.take() else {
             return;
         };
         let atlas = &self.gui.atlas;
@@ -291,6 +346,7 @@ impl Game<'_> {
         let buttons = open.dialog.buttons();
         let in_area = |y: f32| y >= ay && y < ay + ah;
         let mut tooltip = None;
+        let mut item_tip = None;
         let mut start = None;
         for (part, clipped) in layout.placed(open.scroll.amount) {
             if clipped && start.is_none() {
@@ -333,6 +389,64 @@ impl Game<'_> {
                         true,
                     );
                 }
+                Part::Cycle { input, rect } => {
+                    let [x, y, cw, ch] = rect;
+                    let hover = in_area(cursor.1) && ui::hovered(cursor, x, y, cw, ch);
+                    let Some(label) = open
+                        .values
+                        .get(input)
+                        .and_then(|v| open.dialog.inputs[input].control.message(v))
+                    else {
+                        continue;
+                    };
+                    ui::button(batch, atlas, x, y, cw, ch, &label, true, hover);
+                }
+                Part::Slider { input, rect } => {
+                    let [x, y, sw, sh] = rect;
+                    let hover = in_area(cursor.1) && ui::hovered(cursor, x, y, sw, sh);
+                    let Some((InputValue::Slider(position), Some(label))) = open
+                        .values
+                        .get(input)
+                        .map(|v| (v.clone(), open.dialog.inputs[input].control.message(v)))
+                    else {
+                        continue;
+                    };
+                    let held = open.dragging == Some(input);
+                    ui::slider(
+                        batch,
+                        atlas,
+                        x,
+                        y,
+                        sw,
+                        &label,
+                        position,
+                        hover || held,
+                        true,
+                    );
+                }
+                Part::Item { body, rect } => {
+                    let [x, y, iw, ih] = rect;
+                    let Some(Body::Item {
+                        item,
+                        show_decorations,
+                        show_tooltip,
+                        ..
+                    }) = open.dialog.body.get(body)
+                    else {
+                        continue;
+                    };
+                    let Some(stack) = horizon_items::item_nbt::item_from_nbt(item) else {
+                        continue;
+                    };
+                    // ItemDisplayWidget: the item at its corner, then its decorations.
+                    self.draw_item_model(batch, &stack, x, y);
+                    if *show_decorations {
+                        self.draw_item_decorations(batch, &stack, x, y, None);
+                    }
+                    if *show_tooltip && in_area(cursor.1) && ui::hovered(cursor, x, y, iw, ih) {
+                        item_tip = Some(stack);
+                    }
+                }
                 Part::Button { index, rect } => {
                     let [x, y, bw, bh] = rect;
                     let hover =
@@ -371,6 +485,10 @@ impl Game<'_> {
                 .collect();
             ui::tooltip(batch, atlas, &lines, cursor);
         }
+        self.dialogs.open = Some(open);
+        if let Some(stack) = item_tip {
+            self.draw_stack_tooltip(batch, &stack, cursor.0, cursor.1);
+        }
     }
 
     /// A left click on a dialog screen.
@@ -420,6 +538,7 @@ impl Game<'_> {
             self.dialogs.warning = true;
             return Ok(());
         }
+        let shift = self.modifiers.shift_key();
         let Some(open) = self.dialogs.open.as_mut() else {
             return Ok(());
         };
@@ -450,6 +569,23 @@ impl Game<'_> {
                     }
                     action = Some(None);
                 }
+                Part::Cycle {
+                    input,
+                    rect: [x, y, w, h],
+                } if ui::hovered(cursor, x, y, w, h) => {
+                    // CycleButton.onPress: Shift goes back.
+                    cycle(open, input, if shift { -1 } else { 1 });
+                    action = Some(None);
+                }
+                Part::Slider {
+                    input,
+                    rect: [x, y, w, h],
+                } if ui::hovered(cursor, x, y, w, h) => {
+                    open.dragging = Some(input);
+                    if let Some(v) = open.values.get_mut(input) {
+                        *v = InputValue::Slider(ui::slider_value(x, w, cursor.0));
+                    }
+                }
                 Part::Button {
                     index,
                     rect: [x, y, w, h],
@@ -479,17 +615,65 @@ impl Game<'_> {
         self.run_dialog_action(click, after)
     }
 
-    /// The mouse wheel over a dialog: its body scrolls 10 a step.
+    /// The mouse wheel over a dialog: a cycle button under it takes the
+    /// step, else the body scrolls 10 a step.
     pub(super) fn dialog_scroll(&mut self, delta: f32) {
         let Some(layout) = self.dialog_layout() else {
             return;
         };
+        let cursor = self.cursor;
         if let Some(open) = self.dialogs.open.as_mut() {
             let [_, ay, _, ah] = layout.area;
+            if delta != 0.0 && cursor.1 >= ay && cursor.1 < ay + ah {
+                let hovered = layout
+                    .placed(open.scroll.amount)
+                    .find_map(|(part, _)| match part {
+                        Part::Cycle {
+                            input,
+                            rect: [x, y, w, h],
+                        } if ui::hovered(cursor, x, y, w, h) => Some(input),
+                        _ => None,
+                    });
+                if let Some(input) = hovered {
+                    // CycleButton.mouseScrolled: up goes back.
+                    cycle(open, input, if delta > 0.0 { -1 } else { 1 });
+                    return;
+                }
+            }
             open.scroll.wheel(delta, 10.0, ay, ay + ah, layout.content);
         }
     }
 
+    /// The pointer moved with a slider held (`AbstractSliderButton.onDrag`).
+    pub(super) fn dialog_drag(&mut self) {
+        let Some(input) = self.dialogs.open.as_ref().and_then(|o| o.dragging) else {
+            return;
+        };
+        let Some(layout) = self.dialog_layout() else {
+            return;
+        };
+        let x = self.cursor.0;
+        let Some(open) = self.dialogs.open.as_mut() else {
+            return;
+        };
+        let slider = layout.body.iter().find_map(|p| match p {
+            Part::Slider { input: i, rect } if *i == input => Some(*rect),
+            _ => None,
+        });
+        if let (Some([sx, _, sw, _]), Some(value)) = (slider, open.values.get_mut(input)) {
+            *value = InputValue::Slider(ui::slider_value(sx, sw, x));
+        }
+    }
+
+    /// The left button released: a held slider lets go and clicks.
+    pub(super) fn dialog_release(&mut self) {
+        if let Some(open) = self.dialogs.open.as_mut()
+            && open.dragging.take().is_some()
+        {
+            self.audio.play_button_click();
+        }
+    }
+
     /// A key pressed on a dialog screen: Escape closes what allows it, Tab
     /// moves between the text inputs, the rest goes to the focused one
     /// (`shortcut`: the press as an edit shortcut; `text`: what it types).

crates/horizon-client/src/game/dispenser.rs

@@ -296,7 +296,7 @@ pub(super) fn mob_set_slot(m: &mut Mob, slot: Slot, stack: ItemStack) {
     let item: Arc<str> = stack.item.clone();
     let x = &mut m.extra;
     match slot {
-        Slot::MainHand => x.main_hand = Some(item),
+        Slot::MainHand => x.set_main_hand(Some(item)),
         Slot::OffHand => x.off_hand = Some(item),
         Slot::Feet => x.feet = Some(item),
         Slot::Legs => x.legs = Some(item),

crates/horizon-client/src/game/dragon.rs

@@ -801,10 +801,7 @@ impl Game<'_> {
             }
             if !self.fight.killed {
                 if self.dragon.is_none() {
-                    // createNewDragon: over the podium, holding pattern, a random yaw.
-                    let yaw = self.world.random.next_float() * 360.0;
-                    let seed = self.world.random.next_long();
-                    self.dragon = Some(Dragon::new(Vec3::new(0.0, 128.0, 0.0), yaw, seed));
+                    self.create_new_dragon();
                 }
                 self.fight.crystal_scan += 1;
                 if self.fight.crystal_scan >= 100 {
@@ -2593,54 +2590,9 @@ impl Game<'_> {
             self.crystal_beam(pos, to - pos, self.ticks as f32 + a, camera, out);
         }
     }
-    /// `submitRays`: the death rays from a fixed seed, fading in white to magenta.
+    /// `EnderDragonRenderer.submitRays`: untextured, additive death rays.
     fn dragon_rays(&self, base: glam::Mat4, t: f32, out: &mut Vec<Vertex>) {
-        let white = self.gui.atlas.font.white();
-        let uv = [white.u0, white.v0];
-        let over = if t > 0.8 {
-            ((t - 0.8) / 0.2).min(1.0)
-        } else {
-            0.0
-        };
-        let inner = (((1.0 - over) * 255.0) as u32) << 24 | 0x00FF_FFFF;
-        let outer = 0x00FF_00FF;
-        let mut random = LegacyRandom::new(432);
-        let mut m = base;
-        let count = ((t + t * t) / 2.0 * 60.0).floor() as i32;
-        let half_sqrt3 = 3f32.sqrt() / 2.0;
-        let tau = std::f32::consts::TAU;
-        for _ in 0..count {
-            let mut f = || random.next_float() * tau;
-            let q1 = glam::Quat::from_rotation_x(f())
-                * glam::Quat::from_rotation_y(f())
-                * glam::Quat::from_rotation_z(f());
-            let (a, b, c) = (f(), f(), f());
-            let q2 = glam::Quat::from_rotation_x(a)
-                * glam::Quat::from_rotation_y(b)
-                * glam::Quat::from_rotation_z(c + t * std::f32::consts::FRAC_PI_2);
-            m *= glam::Mat4::from_quat(q1 * q2);
-            let length = random.next_float() * 20.0 + 5.0 + over * 10.0;
-            let width = random.next_float() * 2.0 + 1.0 + over * 2.0;
-            let o = glam::Vec3::ZERO;
-            let left = glam::Vec3::new(-half_sqrt3 * width, length, -0.5 * width);
-            let right = glam::Vec3::new(half_sqrt3 * width, length, -0.5 * width);
-            let bottom = glam::Vec3::new(0.0, length, width);
-            for (p1, p2) in [(left, right), (right, bottom), (bottom, left)] {
-                // A triangle as a quad with its last corner repeated.
-                for (p, c) in [(o, inner), (p1, outer), (p2, outer), (p2, outer)] {
-                    out.push(Vertex {
-                        normal: [0; 4],
-                        pos: m.transform_point3(p).to_array(),
-                        uv,
-                        layer: 2,
-                        color: c,
-                        light: 0,
-
-                        glint_uv: [0.0, 0.0],
-                    });
-                }
-            }
-        }
+        dragon_rays(base, t, self.gui.atlas.font.white(), out);
     }
     /// `submitCrystalBeams`: an eight-sided tube from `from` (+2 up) along
     /// `delta`, the beam texture scrolling along it.
@@ -3022,10 +2974,17 @@ impl Game<'_> {
     }
     /// `EnderDragon.kill` (`/kill`): `Entity.kill` removes the entity, it
     /// does not hurt it (the dragon flies its death flight when its health
-    /// runs out).
+    /// runs out). The fight's dragon ends the fight there and then
+    /// (`dragonFight.setDragonKilled`): the exit portal, a gateway and the
+    /// first dragon's egg, and no new dragon. No experience: `tickDeath`
+    /// drops it, and a killed dragon never gets there.
     pub(super) fn kill_dragon(&mut self, id: u32) {
         if self.dragon.as_ref().is_some_and(|d| d.id == id) {
             self.dragon = None;
+            // ServerLevel.getDragonFight: only the End has a fight.
+            if self.dim == Dim::End {
+                self.dragon_killed();
+            }
         }
     }
     /// Any entity touching `room` (`Level.getEntities(null, box)`).
@@ -3317,6 +3276,12 @@ impl Game<'_> {
             }
         }
     }
+    /// `EnderDragonFight.createNewDragon`: over the podium, holding pattern, a random yaw.
+    fn create_new_dragon(&mut self) {
+        let yaw = self.world.random.next_float() * 360.0;
+        let seed = self.world.random.next_long();
+        self.dragon = Some(Dragon::new(Vec3::new(0.0, 128.0, 0.0), yaw, seed));
+    }
     /// The END stage: the portal crystals blow up (no block damage) and a
     /// new dragon takes over.
     fn finish_respawn(&mut self) {
@@ -3343,6 +3308,31 @@ impl Game<'_> {
             }
         }
         self.fight.killed = false;
+        // setRespawnStage(END): the new dragon is summoned for every player
+        // of the fight (the boss bar's players: alive within 192 blocks).
+        self.create_new_dragon();
+        let view = self
+            .dragon
+            .as_ref()
+            .map(|d| horizon_client::advancements::EntityView {
+                kind: "minecraft:ender_dragon".to_owned(),
+                position: [d.position.x, d.position.y, d.position.z],
+                ..Default::default()
+            });
+        if let Some(view) = view {
+            self.for_each_player(|g| {
+                let near = g.player.as_ref().is_some_and(|p| {
+                    !p.health.dead_or_dying()
+                        && p.position.x.powi(2)
+                            + (p.position.y - 128.0).powi(2)
+                            + p.position.z.powi(2)
+                            <= 192.0 * 192.0
+                });
+                if near {
+                    g.trigger_entity("minecraft:summoned_entity", "entity", &view);
+                }
+            });
+        }
         self.fight.dirty = true;
         self.count_crystals();
     }
@@ -3562,10 +3552,93 @@ impl Game<'_> {
     }
 }
 
+/// `submitRays`: the death rays from a fixed seed, fading in white to magenta.
+fn dragon_rays(base: glam::Mat4, t: f32, white: horizon_client::hud::Rect, out: &mut Vec<Vertex>) {
+    // Vanilla's dragonRays has no texture. Sample inside the white sprite:
+    // its border can round into transparent neighbours during interpolation.
+    let uv = [(white.u0 + white.u1) / 2.0, (white.v0 + white.v1) / 2.0];
+    let over = if t > 0.8 {
+        ((t - 0.8) / 0.2).min(1.0)
+    } else {
+        0.0
+    };
+    let inner = (((1.0 - over) * 255.0) as u32) << 24 | 0x00FF_FFFF;
+    let outer = 0x00FF_00FF;
+    let mut random = LegacyRandom::new(432);
+    let mut m = base;
+    let count = ((t + t * t) / 2.0 * 60.0).floor() as i32;
+    let half_sqrt3 = 3f32.sqrt() / 2.0;
+    let tau = std::f32::consts::TAU;
+    for _ in 0..count {
+        let mut f = || random.next_float() * tau;
+        let q1 = glam::Quat::from_rotation_x(f())
+            * glam::Quat::from_rotation_y(f())
+            * glam::Quat::from_rotation_z(f());
+        let (a, b, c) = (f(), f(), f());
+        let q2 = glam::Quat::from_rotation_x(a)
+            * glam::Quat::from_rotation_y(b)
+            * glam::Quat::from_rotation_z(c + t * std::f32::consts::FRAC_PI_2);
+        m *= glam::Mat4::from_quat(q1 * q2);
+        let length = random.next_float() * 20.0 + 5.0 + over * 10.0;
+        let width = random.next_float() * 2.0 + 1.0 + over * 2.0;
+        let o = glam::Vec3::ZERO;
+        let left = glam::Vec3::new(-half_sqrt3 * width, length, -0.5 * width);
+        let right = glam::Vec3::new(half_sqrt3 * width, length, -0.5 * width);
+        let bottom = glam::Vec3::new(0.0, length, width);
+        for (p1, p2) in [(left, right), (right, bottom), (bottom, left)] {
+            // A triangle as a quad with its last corner repeated.
+            for (p, c) in [(o, inner), (p1, outer), (p2, outer), (p2, outer)] {
+                out.push(Vertex {
+                    normal: [0; 4],
+                    pos: m.transform_point3(p).to_array(),
+                    uv,
+                    layer: 2,
+                    color: c,
+                    light: 0,
+
+                    glint_uv: [0.0, 0.0],
+                });
+            }
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[test]
+    fn death_rays_sample_inside_the_white_sprite() {
+        // A four-texel white sprite surrounded by transparent atlas pixels.
+        // A border UV can round outside it during perspective interpolation.
+        let size = 1024.0;
+        let white = horizon_client::hud::Rect {
+            u0: 20.0 / size,
+            v0: 60.0 / size,
+            u1: 24.0 / size,
+            v1: 64.0 / size,
+            w: 4,
+            h: 4,
+        };
+        for t in [0.25, 0.8, 0.95, 1.0] {
+            let mut vertices = Vec::new();
+            dragon_rays(glam::Mat4::IDENTITY, t, white, &mut vertices);
+            assert!(!vertices.is_empty());
+            for v in &vertices {
+                assert!(
+                    v.uv[0] > white.u0 + 0.5 / size && v.uv[0] < white.u1 - 0.5 / size,
+                    "death-ray U touches the atlas border: {}",
+                    v.uv[0]
+                );
+                assert!(
+                    v.uv[1] > white.v0 + 0.5 / size && v.uv[1] < white.v1 - 0.5 / size,
+                    "death-ray V touches the atlas border: {}",
+                    v.uv[1]
+                );
+            }
+        }
+    }
+
     fn dragon(phase: Phase) -> Dragon {
         let mut d = Dragon::new(Vec3::new(0.0, 70.0, 0.0), 0.0, 1);
         d.phase = phase;

crates/horizon-client/src/game/end.rs

@@ -3,6 +3,7 @@
 //! sky. The dragon fight itself lives in game/dragon.rs: the podium is
 //! inactive until the dragon dies.
 use super::{Dim, Game};
+use horizon_client::nether_portal::ENTITY_DELAY;
 use horizon_client::{
     Result,
     containers::{BlockEntity, EndGateway},
@@ -16,10 +17,18 @@ use horizon_client::{
 };
 use horizon_core::{
     geometry::Vec3,
+    position::BlockPos,
     random::{LegacyRandom, RandomSource},
 };
+use horizon_world::nbt::Tag;
+
 use std::{collections::HashMap, sync::Arc};
 
+/// A list of doubles, as an NBT list of them.
+fn doubles(values: [f64; 3]) -> Tag {
+    Tag::List(values.iter().map(|v| Tag::Double(v.to_bits())).collect())
+}
+
 /// ServerLevel.END_SPAWN_POINT.
 pub(super) const END_SPAWN: [i32; 3] = [100, 50, 0];
 /// EnderDragonFight gateway ring radius and height.
@@ -38,6 +47,18 @@ pub(super) enum GatewayJob {
     Known { exit: [i32; 3], exact: bool },
 }
 
+/// An entity travelling through an End gateway: its saved compound and the
+/// job that finds where it lands (`TheEndGatewayBlockEntity.getPortalPosition`).
+#[derive(Clone, Debug)]
+struct GatewayArrival {
+    /// The entity's compound, as it waits for the exit's chunks.
+    tag: Tag,
+    /// The gateway's exit, or the search for one.
+    job: GatewayJob,
+    /// The spot to load before the job is resolved.
+    target: Vec3,
+}
+
 impl GatewayJob {
     /// TheEndGatewayBlockEntity.getPortalPosition, with legacy save fallbacks.
     fn for_gateway(
@@ -94,6 +115,11 @@ pub(super) struct EndState {
     job: Option<GatewayJob>,
     /// Ticks until the player can use a gateway again (TheEndGatewayBlockEntity cooldown).
     gateway_cooldown: u32,
+    gateways: HashMap<u32, horizon_client::end_gateway::Traveller>,
+    /// The entities that went through a gateway, waiting for its exit.
+    arrivals: Vec<GatewayArrival>,
+    /// The chunks kept loaded for those arrivals.
+    areas: Vec<(i32, i32)>,
     /// The Overworld generator, for stronghold positions (ServerLevel.findNearestMapStructure).
     locator: std::sync::Mutex<Option<Arc<VanillaTerrain>>>,
     /// Thrown eyes of ender in flight.
@@ -947,6 +973,17 @@ impl Game<'_> {
         self.save_gateway_exits()
     }
 
+    /// The exit a gateway already leads to: its block entity, or the side file
+    /// that kept it for a gateway whose chunk is not loaded.
+    fn known_gateway_exit(&mut self, gateway: [i32; 3]) -> Option<([i32; 3], bool)> {
+        let key = (gateway[0], gateway[1], gateway[2]);
+        let saved = match self.world.block_entities.get(&key) {
+            Some(BlockEntity::EndGateway(g)) => g.exit_portal.map(|exit| (exit, g.exact_teleport)),
+            _ => None,
+        };
+        saved.or_else(|| self.gateway_exits().get(&gateway).copied())
+    }
+
     /// EndGatewayBlock.entityInside and TheEndGatewayBlockEntity.getPortalPosition:
     /// travel within the End, waiting for the destination chunks to load.
     fn enter_gateway(&mut self, gateway: [i32; 3]) -> Result<()> {
@@ -1043,13 +1080,7 @@ impl Game<'_> {
     /// The teleport position of a gateway job, creating the exit gateway (and
     /// an island when the chunk has no landing spot) for new destinations.
     pub(super) fn resolve_gateway(&mut self, job: GatewayJob, target: Vec3) -> Result<Vec3> {
-        let bottom_center = |p: [i32; 3]| {
-            Vec3::new(
-                f64::from(p[0]) + 0.5,
-                f64::from(p[1]),
-                f64::from(p[2]) + 0.5,
-            )
-        };
+        let bottom_center = horizon_client::end_gateway::bottom_center;
         let find_exit = |game: &Self, exit: [i32; 3]| {
             let p = game.tallest_block([exit[0], exit[1] + 2, exit[2]], 5, false);
             [p[0], p[1] + 1, p[2]]
@@ -1059,6 +1090,14 @@ impl Game<'_> {
                 find_exit(self, e)
             }))),
             GatewayJob::Find { gateway, exact } => {
+                // The player and the entities may resolve the same gateway: the
+                // first one to arrive finds the exit, the others use it.
+                let known = self.known_gateway_exit(gateway);
+                if let Some((exit, exact)) = known {
+                    return Ok(bottom_center(exit_target(exit, exact, |e| {
+                        find_exit(self, e)
+                    })));
+                }
                 // findExitPortalXZPosTentative over the loaded chunks.
                 let dir = glam::DVec2::new(f64::from(gateway[0]), f64::from(gateway[2]))
                     .normalize_or_zero();
@@ -1420,6 +1459,194 @@ impl Game<'_> {
             }
         }
     }
+
+    // ---- End gateway travel for the entities ----
+
+    /// `EndGatewayBlock.entityInside` for the items and mobs in the End: the
+    /// gateway blocks their box swept through. A gateway that is cooling down
+    /// (`TheEndGatewayBlockEntity.triggerCooldown`) takes nobody in.
+    pub(super) fn find_end_gateway_portals(&mut self) {
+        if self.remote.is_some() || self.dim != Dim::End {
+            return;
+        }
+        let items: Vec<(u32, Vec3, f32, f32)> = self
+            .dropped
+            .iter()
+            .map(|e| (e.id, e.position, 0.25, 0.25))
+            .collect();
+        let mobs: Vec<(u32, Vec3, f32, f32)> = self
+            .mobs
+            .iter()
+            .filter(|m| self.mob_can_use_portal(m))
+            .map(|m| (m.id, m.position, m.width(), m.height()))
+            .collect();
+        let mut inside: Vec<(u32, BlockPos)> = Vec::new();
+        for (id, to, width, height) in items.into_iter().chain(mobs) {
+            let from = self.portals.before.get(&id).copied().unwrap_or(to);
+            let found = horizon_client::end_gateway::swept_gateway(from, to, width, height, |p| {
+                &*self.res.facts().get(self.world.block(p.x, p.y, p.z)).name
+                    == "minecraft:end_gateway"
+            });
+            if let Some(pos) = found {
+                inside.push((id, pos));
+            }
+        }
+        for (id, pos) in inside {
+            // One entity at a time: the gateway cools down for 40 ticks.
+            if !self.gateway_enter([pos.x, pos.y, pos.z]) {
+                continue;
+            }
+            // An entity that just came through any portal stays out of this one.
+            if self.restart_portal_cooldown(id) {
+                continue;
+            }
+            self.end.gateways.entry(id).or_default().enter(pos);
+        }
+    }
+
+    /// `Entity.handlePortal` for the entities in an End gateway: they go
+    /// through to the gateway's exit, where they wait for its chunks.
+    pub(super) fn handle_end_gateway_portals(&mut self) {
+        if self.remote.is_some() || self.dim != Dim::End {
+            return;
+        }
+        let ids: Vec<(u32, bool)> = self
+            .dropped
+            .iter()
+            .map(|e| (e.id, true))
+            .chain(self.mobs.iter().map(|m| (m.id, self.mob_can_use_portal(m))))
+            .collect();
+        let present: std::collections::HashSet<u32> = ids.iter().map(|(id, _)| *id).collect();
+        self.end.gateways.retain(|id, _| present.contains(id));
+        let mut leaving: Vec<(u32, BlockPos)> = Vec::new();
+        for (id, allowed) in ids {
+            let Some(state) = self.end.gateways.get_mut(&id) else {
+                continue;
+            };
+            // The End gateway has no transition time (Portal.getPortalTransitionTime).
+            if let Some(entry) = state.travel(allowed) {
+                leaving.push((id, entry));
+            }
+            if state.is_done() {
+                self.end.gateways.remove(&id);
+            }
+        }
+        for (id, entry) in leaving {
+            self.send_through_gateway(id, entry);
+        }
+    }
+
+    /// `Entity.teleportToPortalDestination` for an entity that goes through an
+    /// End gateway: it is saved and waits for the exit's chunks.
+    fn send_through_gateway(&mut self, id: u32, gateway: BlockPos) {
+        let tag = if let Some(i) = self.dropped.iter().position(|e| e.id == id) {
+            let uuid = self.uuid_for(id);
+            let tag = horizon_client::entity_nbt::item_entity_to_nbt(
+                &self.dropped[i],
+                uuid,
+                self.persist_raw(id),
+            );
+            self.dropped.remove(i);
+            self.forget_entity(id);
+            tag
+        } else if let Some(i) = self.mobs.iter().position(|m| m.id == id) {
+            let mut tag = self.mob_tree_nbt(i);
+            // Entity.removeAfterChangingDimensions drops the leash.
+            if let Tag::Compound(c) = &mut tag {
+                c.remove(&"leash".into());
+            }
+            // The mobs riding it travel with it (their tags are in its compound).
+            let mut gone = vec![id];
+            let mut k = 0;
+            while k < gone.len() {
+                let v = gone[k];
+                gone.extend(
+                    self.mobs
+                        .iter()
+                        .filter(|m| m.extra.mount == Some(v))
+                        .map(|m| m.id),
+                );
+                k += 1;
+            }
+            self.mobs.retain(|m| !gone.contains(&m.id));
+            for g in gone {
+                self.forget_entity(g);
+            }
+            tag
+        } else {
+            return;
+        };
+        let (job, target) = self.gateway_job([gateway.x, gateway.y, gateway.z]);
+        self.end.arrivals.push(GatewayArrival { tag, job, target });
+    }
+
+    /// The entities that reached a gateway's exit: they land where the
+    /// gateway leads, once its chunks have loaded.
+    pub(super) fn resolve_end_gateway_arrivals(&mut self) -> Result<()> {
+        if self.remote.is_some() || self.dim != Dim::End {
+            return Ok(());
+        }
+        let mut i = 0;
+        while i < self.end.arrivals.len() {
+            let (cx, cz) = (
+                (self.end.arrivals[i].target.x.floor() as i32) >> 4,
+                (self.end.arrivals[i].target.z.floor() as i32) >> 4,
+            );
+            if !self.world.chunks.contains_key(&(cx, cz)) {
+                i += 1;
+                continue;
+            }
+            let (job, target) = (self.end.arrivals[i].job, self.end.arrivals[i].target);
+            let at = match self.resolve_gateway(job, target) {
+                Ok(at) => at,
+                Err(e) => {
+                    // The traveller waits for the exit: the failure is retried.
+                    log::warn!("End gateway: {e}");
+                    i += 1;
+                    continue;
+                }
+            };
+            let mut tag = self.end.arrivals.remove(i).tag;
+            if let Tag::Compound(c) = &mut tag {
+                c.insert("Pos".into(), doubles([at.x, at.y, at.z]));
+                c.insert("Motion".into(), doubles([0.0, 0.0, 0.0]));
+                // setPortalCooldown before the teleport.
+                c.insert("PortalCooldown".into(), Tag::Int(ENTITY_DELAY));
+            }
+            let key = ((at.x.floor() as i32) >> 4, (at.z.floor() as i32) >> 4);
+            match self
+                .world
+                .loaded_entities
+                .iter_mut()
+                .find(|(k, _)| *k == key)
+            {
+                Some((_, tags)) => tags.push(tag),
+                None => self.world.loaded_entities.push((key, vec![tag])),
+            }
+        }
+        Ok(())
+    }
+
+    /// The chunks the entities waiting to arrive need, kept loaded like the
+    /// areas a server keeps around its players.
+    pub(super) fn keep_gateway_destinations(&mut self) {
+        let areas = &self.end.areas;
+        self.streaming
+            .extra
+            .retain(|&(c, r)| !(r == 1 && areas.contains(&c)));
+        let mut areas = Vec::new();
+        for a in &self.end.arrivals {
+            let c = (
+                (a.target.x.floor() as i32) >> 4,
+                (a.target.z.floor() as i32) >> 4,
+            );
+            if !areas.contains(&c) {
+                areas.push(c);
+                self.streaming.extra.push((c, 1));
+            }
+        }
+        self.end.areas = areas;
+    }
 }
 
 #[cfg(test)]

crates/horizon-client/src/game/functions.rs

@@ -36,6 +36,8 @@ pub(super) struct FnState {
     load_pending: bool,
     pub schedule: Vec<Scheduled>,
     next_seq: u64,
+    /// A dedicated server's `function-permission-level`.
+    pub permission: Option<u8>,
 }
 /// What a function reported through `return`.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -45,6 +47,16 @@ pub(super) enum Outcome {
     Fail,
 }
 
+impl FnState {
+    /// The level function files compile at (`ServerFunctionLibrary`'s
+    /// `functionCompilationPermissions`): `function-permission-level` on a
+    /// dedicated server, game master (2) otherwise. Whoever runs a function,
+    /// its commands need no more than this.
+    fn command_level(&self) -> u8 {
+        self.permission.unwrap_or(2)
+    }
+}
+
 impl Game<'_> {
     // ---- loading -----------------------------------------------------------
 
@@ -278,6 +290,7 @@ impl Game<'_> {
         }
         self.exec.function_depth += 1;
         let outer = self.exec.returned.take();
+        let level = std::mem::replace(&mut self.ui.registries.permission, self.fns.command_level());
         let inner = Source {
             silent: true,
             store: None,
@@ -292,6 +305,7 @@ impl Game<'_> {
                 break;
             }
         }
+        self.ui.registries.permission = level;
         let returned = std::mem::replace(&mut self.exec.returned, outer);
         self.exec.function_depth -= 1;
         Ok(match returned {
@@ -572,6 +586,75 @@ impl Game<'_> {
             .chain(self.fns.enabled.iter().cloned())
             .collect()
     }
+    /// `FileUtil.isPathPartPortable`: no trailing dot and no Windows device
+    /// name (CON, PRN, AUX, NUL, COM and LPT with a digit from 1 to 9).
+    fn is_portable_name(name: &str) -> bool {
+        let stem = name.split('.').next().unwrap_or_default();
+        let device = match stem.len() {
+            3 => matches!(stem, "com" | "con" | "prn" | "aux" | "nul"),
+            4 => matches!(&stem[..3], "com" | "lpt") && matches!(stem.as_bytes()[3], b'1'..=b'9'),
+            _ => false,
+        };
+        !device && !name.ends_with('.')
+    }
+    /// `DataPackCommand.createPack`: a pack folder with its `data` folder and a
+    /// `pack.mcmeta` in the world's datapacks folder.
+    fn create_pack(&mut self, ctx: &Context) -> R<i32> {
+        let id = match ctx.get("id") {
+            Some(Arg::Str(s)) => s.clone(),
+            _ => String::new(),
+        };
+        let description = self.component_arg(ctx, "description")?;
+        // FileUtil.isValidPathSegment: lowercase letters, digits, '-', '.' and '_'.
+        let valid = !id.is_empty()
+            && id != "."
+            && id != ".."
+            && id
+                .chars()
+                .all(|c| matches!(c, 'a'..='z' | '0'..='9' | '-' | '.' | '_'));
+        if !valid {
+            return Err(err("commands.datapack.create.invalid_name", &[&id]));
+        }
+        if !Self::is_portable_name(&id) {
+            return Err(err("commands.datapack.create.invalid_full_name", &[&id]));
+        }
+        // Without a world there is no datapacks folder to write to.
+        if self.world_root.as_os_str().is_empty() {
+            return Err(err("commands.datapack.create.io_failure", &[&id]));
+        }
+        let datapacks = self.world_root.join("datapacks");
+        let pack = datapacks.join(&id);
+        if pack.exists() {
+            return Err(err("commands.datapack.create.already_exists", &[&id]));
+        }
+        // The data pack version (SharedConstants), written as a bare major
+        // number for both bounds, as vanilla does.
+        let pack_format = horizon_core::version::DATA_PACK_FORMAT.0;
+        let mcmeta = serde_json::json!({
+            "pack": {
+                "description": description.component(),
+                "min_format": pack_format,
+                "max_format": pack_format,
+            }
+        });
+        let written = std::fs::create_dir_all(&datapacks)
+            .and_then(|()| std::fs::create_dir(&pack))
+            .and_then(|()| std::fs::create_dir(pack.join("data")))
+            .and_then(|()| {
+                std::fs::write(
+                    pack.join("pack.mcmeta"),
+                    serde_json::to_string_pretty(&mcmeta).unwrap_or_default(),
+                )
+            });
+        if written.is_err() {
+            return Err(err("commands.datapack.create.io_failure", &[&id]));
+        }
+        self.feedback(Text::translate(
+            "commands.datapack.create.success",
+            &[Text::literal(id)],
+        ));
+        Ok(1)
+    }
     pub(super) fn cmd_datapack(&mut self, id: &str, ctx: &Context) -> R<i32> {
         self.ensure_datapacks();
         let name = match ctx.get("name") {
@@ -590,6 +673,7 @@ impl Game<'_> {
                 || g.fns.packs.iter().any(|p| p.id == n)
         };
         match id {
+            "datapack.create" => self.create_pack(ctx),
             "datapack.list" => {
                 let want_enabled = ctx.has("enabled") || (!ctx.has("available"));
                 let want_available = ctx.has("available") || (!ctx.has("enabled"));

crates/horizon-client/src/game/golems.rs

@@ -85,8 +85,36 @@ impl Game<'_> {
         {
             m.extra.player_created = true;
         }
+        self.trigger_golem_summoned(id);
         self.update_pattern_blocks(&blocks)
     }
+    /// `CarvedPumpkinBlock.spawnGolemInWorld`: SUMMONED_ENTITY for each player
+    /// whose box is within 5 blocks of the golem's box (the local player here).
+    fn trigger_golem_summoned(&mut self, id: Option<u32>) {
+        let Some(golem) = id
+            .and_then(|id| self.mobs.iter().find(|m| m.id == id))
+            .cloned()
+        else {
+            return;
+        };
+        let me = self.player_entity();
+        let half = f64::from(golem.width()) / 2.0;
+        let height = f64::from(golem.height());
+        let reach = 5.0;
+        let [x, y, z] = me.position;
+        let p = golem.position;
+        // The player's box is 0.6 wide and 1.8 tall.
+        let near = x + 0.3 >= p.x - half - reach
+            && x - 0.3 <= p.x + half + reach
+            && y + 1.8 >= p.y - reach
+            && y <= p.y + height + reach
+            && z + 0.3 >= p.z - half - reach
+            && z - 0.3 <= p.z + half + reach;
+        if near {
+            let view = self.mob_entity(&golem);
+            self.trigger_entity("minecraft:summoned_entity", "entity", &view);
+        }
+    }
     /// Whether placing a golem head at `head` completes a golem.
     pub(super) fn completes_golem(&self, head: [i32; 3]) -> bool {
         self.find_golem(head).is_some() || self.copper_golem_base(head)
@@ -192,6 +220,7 @@ impl Game<'_> {
             f64::from(head[2]) + 0.5,
         ];
         let id = self.create_triggered("minecraft:copper_golem", at, 0.0);
+        self.trigger_golem_summoned(id);
         self.update_pattern_blocks(&cells)?;
         let direction = match facing.as_str() {
             "south" => horizon_core::geometry::Direction::South,

crates/horizon-client/src/game/hand.rs

@@ -10,12 +10,14 @@ use horizon_client::{
     first_person::{Hand, HandWorld, Hit, SwingAnimation, UseResult, swing_duration},
     items::ItemStack,
 };
+use horizon_core::geometry::{Aabb, Vec3};
 
 /// The off hand's place in `visible_hands` (the main hand uses its hotbar slot).
 const OFFHAND: usize = usize::MAX;
 
-/// `AttackRange.isInRange`: float bounds, then inclusive double comparison.
-fn attack_range_contains(range: &serde_json::Value, distance: f64, creative: bool) -> bool {
+/// `AttackRange.effectiveMinRange`, `effectiveMaxRange` (for a player) and
+/// `hitboxMargin` of an `attack_range` component.
+fn attack_reach(range: &serde_json::Value, creative: bool) -> (f32, f32, f32) {
     let value = |key: &str, default: f32| range[key].as_f64().map_or(default, |v| v as f32);
     let (min, max) = if creative {
         (
@@ -25,13 +27,45 @@ fn attack_range_contains(range: &serde_json::Value, distance: f64, creative: boo
     } else {
         (value("min_reach", 0.0), value("max_reach", 3.0))
     };
-    let margin = value("hitbox_margin", 0.3);
+    (min, max, value("hitbox_margin", 0.3))
+}
+
+fn v3(v: [f64; 3]) -> Vec3 {
+    Vec3::new(v[0], v[1], v[2])
+}
+
+/// `LocalPlayer.raycastHitResult` with an item that has an attack range
+/// (`AttackRange.getClosesetHit`): the distance from the eye to the nearest
+/// box hit along the item's own `reach`, which goes past the plain pick's
+/// 3 blocks (a spear's 4.5). A miss falls back to the plain pick (`None`).
+fn reach_pick(
+    boxes: &[(usize, Aabb)],
+    eye: Vec3,
+    look: Vec3,
+    movement: Vec3,
+    reach: (f32, f32, f32),
+    clip: impl Fn(Vec3, Vec3) -> Option<Vec3>,
+) -> Option<f64> {
+    super::spear::hits_in_reach(boxes, eye, look, movement, reach, clip)
+        .into_iter()
+        .map(|(_, at)| eye.distance_squared(at).sqrt())
+        .reduce(f64::min)
+}
+
+/// `AttackRange.isInRange`: float bounds, then inclusive double comparison.
+fn attack_range_contains(range: &serde_json::Value, distance: f64, creative: bool) -> bool {
+    let (min, max, margin) = attack_reach(range, creative);
     distance >= f64::from(min - margin) && distance <= f64::from(max + margin)
 }
 
 impl Game<'_> {
     /// Opening a screen stops breaking before the next game tick (which may pause).
     pub(super) fn stop_mining(&mut self) {
+        if self.clicks.destroying.active {
+            let pos = self.clicks.destroying.pos;
+            let state = self.world.block(pos[0], pos[1], pos[2]);
+            self.tutorial_destroy(state, -1.0);
+        }
         let mut destroying = std::mem::take(&mut self.clicks.destroying);
         destroying.stop(&mut GameHands {
             game: self,
@@ -112,6 +146,12 @@ impl Game<'_> {
             progress: d.progress,
             ticks: d.ticks as u32,
         });
+        if let Some(mining) = &self.mining {
+            let pos = mining.pos;
+            let progress = mining.progress;
+            let state = self.world.block(pos[0], pos[1], pos[2]);
+            self.tutorial_destroy(state, progress);
+        }
         Ok(())
     }
     /// `BlockBehaviour.getDestroyProgress` with `Player.getDestroySpeed`.
@@ -261,10 +301,6 @@ impl Game<'_> {
     /// it is alive (the nearest entity under the crosshair, before any block).
     pub(super) fn crosshair_living(&self) -> Option<bool> {
         let nearest = |hits: &[Option<f64>]| hits.iter().flatten().copied().reduce(f64::min);
-        let living = nearest(&[
-            self.mob_hit().map(|h| h.1),
-            self.armor_stand_hit().map(|h| h.1),
-        ])?;
         let other = nearest(&[
             self.painting_hit().map(|h| h.1),
             self.frame_hit().map(|h| h.1),
@@ -272,24 +308,49 @@ impl Game<'_> {
             self.cart_hit().map(|h| h.1),
             self.dragon_hit().map(|h| h.1),
         ]);
-        if !self.before_block(living) || other.is_some_and(|o| o <= living) {
-            return None;
-        }
         let active = self
             .using
             .and_then(|(slot, _)| self.inventory.get(slot).and_then(Option::as_ref))
             .or_else(|| self.held());
-        if let Some(stack) = active {
-            let components = self
-                .pack
+        let range = active.and_then(|stack| {
+            self.pack
                 .item_renderer
                 .models
-                .components(&horizon_client::item_render::stack_view(stack));
-            if let Some(range) = components.get("minecraft:attack_range")
-                && !attack_range_contains(range, living, self.creative)
-            {
-                return None;
-            }
+                .components(&horizon_client::item_render::stack_view(stack))
+                .get("minecraft:attack_range")
+                .cloned()
+        });
+        let spear = range.as_ref().and_then(|r| {
+            let eye = self.eye_position()?;
+            let look = super::view_vector(self.yaw, self.pitch);
+            let reach = attack_reach(r, self.creative);
+            let boxes = self.hittable_mob_boxes();
+            let clip = |from: Vec3, to: Vec3| {
+                let length = from.distance_squared(to).sqrt();
+                let d = to.subtract(from).scale(1.0 / length);
+                (length > 0.0)
+                    .then(|| self.clip_ray([from.x, from.y, from.z], [d.x, d.y, d.z], length))
+                    .flatten()
+                    .map(|hit| Vec3::new(hit.point[0], hit.point[1], hit.point[2]))
+            };
+            let movement = self.known_player_movement();
+            reach_pick(&boxes, v3(eye), v3(look), movement, reach, clip)
+        });
+        let living = match spear {
+            Some(distance) => distance,
+            None => nearest(&[
+                self.mob_hit().map(|h| h.1),
+                self.armor_stand_hit().map(|h| h.1),
+            ])?,
+        };
+        if (spear.is_none() && !self.before_block(living)) || other.is_some_and(|o| o <= living) {
+            return None;
+        }
+        // Hud.extractCrosshair: with an attack range, the hit must be in it.
+        if let Some(range) = &range
+            && !attack_range_contains(range, living, self.creative)
+        {
+            return None;
         }
         // Only alive mobs are hit, so a picked living entity is alive.
         Some(true)
@@ -528,6 +589,8 @@ impl HandWorld for GameHands<'_, '_> {
         {
             return false;
         }
+        let state = self.game.world.block(pos[0], pos[1], pos[2]);
+        self.game.tutorial_destroy(state, 1.0);
         let r = self.game.break_block(pos);
         self.keep(r);
         true
@@ -564,6 +627,40 @@ impl HandWorld for GameHands<'_, '_> {
 mod tests {
     use super::*;
 
+    /// A zombie-sized box whose near face is `distance` blocks ahead of an
+    /// eye at the origin looking along +z.
+    fn mob_ahead(distance: f64) -> Vec<(usize, Aabb)> {
+        let min = Vec3::new(-0.3, -1.0, distance);
+        vec![(0, Aabb::new(min, min.add_vector(Vec3::new(0.6, 1.95, 0.6))))]
+    }
+
+    #[test]
+    fn a_spear_picks_a_mob_past_the_plain_reach() {
+        // #3209: a mob 4 blocks ahead is out of the plain pick's 3 blocks but
+        // within a spear's attack range (min 2, max 4.5, margin 0.125), so the
+        // crosshair picks it and the attack indicator shows.
+        let spear = serde_json::json!({
+            "min_reach": 2.0, "max_reach": 4.5,
+            "min_creative_reach": 2.0, "max_creative_reach": 6.5,
+            "hitbox_margin": 0.125,
+        });
+        let (eye, look) = (Vec3::ZERO, Vec3::new(0.0, 0.0, 1.0));
+        let boxes = mob_ahead(4.0);
+        let reach = attack_reach(&spear, false);
+        let pick = reach_pick(&boxes, eye, look, Vec3::ZERO, reach, |_, _| None);
+        assert_eq!(pick, Some(4.0));
+        assert!(attack_range_contains(&spear, 4.0, false));
+        // Past the maximum plus the margin: no pick.
+        let far = mob_ahead(4.7);
+        assert_eq!(
+            reach_pick(&far, eye, look, Vec3::ZERO, reach, |_, _| None),
+            None
+        );
+        // A block nearer than the minimum reach takes the pick.
+        let wall = |from: Vec3, _: Vec3| Some(from.add_vector(Vec3::new(0.0, 0.0, 1.0)));
+        assert_eq!(reach_pick(&boxes, eye, look, Vec3::ZERO, reach, wall), None);
+    }
+
     #[test]
     fn attack_range_uses_inclusive_float_bounds() {
         let range = serde_json::json!({

crates/horizon-client/src/game/item_draw.rs

@@ -344,11 +344,24 @@ impl Game<'_> {
         pose: glam::Mat4,
         light: u32,
         out: &mut Vec<Vertex>,
+    ) {
+        let lights = diffuse_lights(self.dim == Dim::Nether);
+        self.submit_item_lit(state, pose, light, lights, out);
+    }
+    /// [`Self::submit_item_world`] shaded by other diffuse lights (a
+    /// `Lighting.Entry` other than the level's), in the pose's output space.
+    pub(super) fn submit_item_lit(
+        &self,
+        state: &ItemRenderState,
+        pose: glam::Mat4,
+        light: u32,
+        lights: (glam::Vec3, glam::Vec3),
+        out: &mut Vec<Vertex>,
     ) {
         let mut sink = WorldSink {
             out,
             light,
-            lights: Some(diffuse_lights(self.dim == Dim::Nether)),
+            lights: Some(lights),
             glint: self.glint(),
         };
         state.submit(

crates/horizon-client/src/game/jukebox.rs

@@ -148,6 +148,20 @@ impl Game<'_> {
             self.lan_songs.push((pos, Some(song.to_owned())));
         }
     }
+    /// `LevelEventHandler` 1010 on a client of a server: `playJukeboxSong`
+    /// for the song the event's data names in the server's `jukebox_song`
+    /// registry (`Registry.get(int).ifPresent`: an unknown id does nothing).
+    /// The server's jukebox plays it; this client only hears it.
+    pub(super) fn jukebox_song_event(&mut self, pos: [i32; 3], data: i32) {
+        if let Some(song) = jukebox_song_name(self.remote.as_ref().map(|r| &*r.registries), data) {
+            self.start_song(pos, &song);
+        }
+    }
+    /// `LevelEventHandler` 1011: `stopJukeboxSongAndNotifyNearby`.
+    pub(super) fn jukebox_stop_event(&mut self, pos: [i32; 3]) {
+        self.stop_sound(pos);
+        self.notify_record_playing(pos, false);
+    }
     fn stop_sound(&mut self, pos: [i32; 3]) {
         if let Some(id) = self.jukebox_sounds.remove(&(pos[0], pos[1], pos[2])) {
             self.audio.stop_and_release(id);
@@ -256,15 +270,37 @@ impl Game<'_> {
             .map(|(k, id)| (*k, *id))
             .collect();
         for (k, id) in sounds {
-            if !self.audio.engine.is_active(id)
-                || !matches!(self.world.block_entities.get(&k), Some(BlockEntity::Jukebox(j)) if j.playing)
-            {
+            // A server's client has no playing jukebox of its own: its songs
+            // stop with level event 1011, or when they end.
+            let playing = matches!(self.world.block_entities.get(&k), Some(BlockEntity::Jukebox(j)) if j.playing);
+            if !keeps_song(
+                self.audio.engine.is_active(id),
+                self.remote.is_some(),
+                playing,
+            ) {
                 self.audio.stop_and_release(id);
                 self.jukebox_sounds.remove(&k);
             }
         }
     }
 }
+/// The song a level event 1010's data names: its id in the `jukebox_song`
+/// registry the server sent (`Registry.get(int)`). Only a server's client
+/// has one; a level that plays its own jukeboxes starts their songs itself.
+fn jukebox_song_name(
+    registries: Option<&horizon_protocol::registry::Dynamic>,
+    id: i32,
+) -> Option<String> {
+    registries?
+        .name("minecraft:jukebox_song", id)
+        .map(str::to_owned)
+}
+/// Whether a jukebox song keeps playing: until it ends, and, in a level that
+/// plays its own jukeboxes, while that jukebox plays. A server's client
+/// stops it at level event 1011 (`LevelRenderer.playingJukeboxSongs`).
+fn keeps_song(active: bool, server_client: bool, jukebox_playing: bool) -> bool {
+    active && (server_client || jukebox_playing)
+}
 /// The jukebox's redstone signal (15 while a song plays) and comparator output.
 pub(super) fn jukebox_signals(
     world: &horizon_client::world::World,
@@ -284,3 +320,36 @@ pub(super) fn jukebox_signals(
         _ => None,
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{jukebox_song_name, keeps_song};
+    use horizon_protocol::registry::Dynamic;
+
+    /// On a server's client the song comes from level event 1010, whose data
+    /// is the song's id in the server's `jukebox_song` registry (#3173), and
+    /// it plays on although this client's jukebox isn't playing.
+    #[test]
+    fn a_server_clients_jukebox_song_comes_from_level_event_1010() {
+        let mut registries = Dynamic::default();
+        registries.registries.insert(
+            "minecraft:jukebox_song".into(),
+            ["minecraft:11", "minecraft:13", "minecraft:cat"]
+                .map(|n| (n.to_owned(), None))
+                .to_vec(),
+        );
+        assert_eq!(
+            jukebox_song_name(Some(&registries), 2).as_deref(),
+            Some("minecraft:cat")
+        );
+        assert_eq!(jukebox_song_name(Some(&registries), 3), None);
+        assert_eq!(jukebox_song_name(Some(&registries), -1), None);
+        assert_eq!(jukebox_song_name(None, 2), None);
+        // A server's client: on until the song ends (or level event 1011).
+        assert!(keeps_song(true, true, false));
+        assert!(!keeps_song(false, true, false));
+        // A level that plays its own jukebox: also until the jukebox stops.
+        assert!(keeps_song(true, false, true));
+        assert!(!keeps_song(true, false, false));
+    }
+}

crates/horizon-client/src/game/lan.rs

@@ -69,7 +69,8 @@ pub(super) struct LanHost {
     pub play: HashMap<u32, super::lan_actions::GuestPlay>,
     /// Blocks broken this tick (their sound is a level event for the guests).
     pub broken: Vec<[f64; 3]>,
-    /// Hurt time, death and swing time (while swinging) of the mobs guests see.
+    /// Hurt time, death and swing time (while swinging) of the mobs guests
+    /// see; the players' hurt time by entity id.
     mob_state: HashMap<super::Dim, HashMap<u32, (i32, bool, Option<i32>)>>,
     /// The guest each mob sees as its player, when not the host (game/lan_mobs.rs).
     pub mob_players: HashMap<u32, u32>,
@@ -177,7 +178,8 @@ pub(super) fn baby_index(kind: &str) -> Option<u8> {
         | "minecraft:axolotl"
         | "minecraft:dolphin"
         | "minecraft:squid"
-        | "minecraft:glow_squid" => Some(16),
+        | "minecraft:glow_squid"
+        | "minecraft:sulfur_cube" => Some(16),
         _ => None,
     }
 }
@@ -325,10 +327,12 @@ fn mob_meta(
     defaults: &mut Vec<(u8, i32, Value)>,
 ) {
     let kind = m.kind.id.as_str();
-    // Entity.DATA_SHARED_FLAGS_ID: on fire 0x01, swimming 0x10 (a drowned
-    // under water, `Drowned.setSwimming`), invisible 0x20 (the effect's flag)
-    // and glowing 0x40 (LivingEntity.updateGlowingStatus).
-    let shared = i8::from(m.fire_ticks > 0)
+    // Entity.DATA_SHARED_FLAGS_ID: on fire 0x01, sprinting 0x08 (a dashing
+    // cat or ocelot), swimming 0x10 (a drowned under water,
+    // `Drowned.setSwimming`), invisible 0x20 (the effect's flag) and glowing
+    // 0x40 (LivingEntity.updateGlowingStatus).
+    let shared = i8::from(m.is_on_fire())
+        | i8::from(m.extra.sprinting) << 3
         | i8::from(m.species() == Species::Drowned && m.extra.flag) << 4
         | i8::from(m.invisible || horizon_client::mobs::trader::is_invisible(m)) << 5
         | i8::from(m.is_currently_glowing()) << 6;
@@ -600,10 +604,11 @@ fn mob_meta(
             }
         }
         // AbstractCubeMob.ID_SIZE.
-        "minecraft:slime" | "minecraft:magma_cube" => {
+        "minecraft:slime" | "minecraft:magma_cube" | "minecraft:sulfur_cube" => {
             if e.size > 1 {
                 meta.push((18, serializer::INT, Value::Int(e.size)));
             }
+            defaults.push((18, serializer::INT, Value::Int(1)));
         }
         // Creeper.DATA_SWELL_DIR, DATA_IS_POWERED and DATA_IS_IGNITED: the
         // guest swells the creeper from them. The direction always goes in,
@@ -801,6 +806,14 @@ fn mob_meta(
             }
             defaults.push((18, serializer::BOOLEAN, Value::Bool(false)));
         }
+        // Skeleton.DATA_STRAY_CONVERSION_ID (the first entry after Mob's):
+        // the shaking of the freezing conversion.
+        "minecraft:skeleton" => {
+            if e.counter2 > 0 {
+                meta.push((16, serializer::BOOLEAN, Value::Bool(true)));
+            }
+            defaults.push((16, serializer::BOOLEAN, Value::Bool(false)));
+        }
         // AbstractVillager.DATA_UNHAPPY_COUNTER (after AgeableMob's two).
         "minecraft:wandering_trader" => unhappy_counter(m, meta, defaults),
         // Hoglin.DATA_IMMUNE_TO_ZOMBIFICATION (after AgeableMob's two) and
@@ -1234,15 +1247,53 @@ impl Game<'_> {
     /// Save a guest when they leave or the world closes: an integrated
     /// server's owner with the world (`save_game`), anyone else in their file.
     pub(super) fn save_guest(&mut self, host: &LanHost, guest: &horizon_client::lan::guest::Guest) {
+        // The vehicle the guest rides, for the file that names it.
+        let vehicle = self.root_vehicle_uuid(guest.vehicle);
         if host.owner.as_ref().is_some_and(|o| o.uuid == guest.uuid) {
             if guest.placed {
-                playerdata::store(guest, &mut self.level);
+                playerdata::store(guest, &mut self.level, vehicle);
             }
         } else {
-            playerdata::save(guest, &self.world_root);
+            playerdata::save(guest, &self.world_root, vehicle);
         }
         self.save_guest_records(host, guest);
     }
+    /// `ServerPlayer.loadAndSpawnParentVehicle`: a guest whose file names the
+    /// vehicle it rode rides it again, once the vehicle is in the world.
+    fn restore_guest_vehicles(&mut self, host: &mut LanHost) {
+        let waiting: Vec<(usize, [i32; 4])> = host
+            .hub
+            .guests
+            .iter()
+            .enumerate()
+            .filter_map(|(i, g)| Some((i, g.saved_vehicle?)))
+            .filter(|(i, _)| {
+                let g = &host.hub.guests[*i];
+                let chunk = (
+                    (g.position[0].floor() as i32).div_euclid(16),
+                    (g.position[2].floor() as i32).div_euclid(16),
+                );
+                g.placed
+                    && g.vehicle.is_none()
+                    && g.dimension == self.dim.id()
+                    && g.sent_chunks.contains(&chunk)
+            })
+            .collect();
+        for (i, uuid) in waiting {
+            let raw = host.hub.guests[i].saved.clone();
+            let Some(id) = self.restore_saved_vehicle(uuid, raw.as_ref()) else {
+                continue;
+            };
+            let g = &mut host.hub.guests[i];
+            if let Some(horizon_world::nbt::Tag::Compound(p)) = &mut g.saved {
+                p.remove(&"RootVehicle".into());
+            }
+            g.vehicle = Some(id);
+            g.saved_vehicle = None;
+            // Pair the stationary restored entities before their passenger packet.
+            g.moved = true;
+        }
+    }
     /// The file name of a player's advancements and statistics: an
     /// integrated server's owner keeps single player's.
     fn records_uuid(&self, host: &LanHost, uuid: u128) -> Option<[i32; 4]> {
@@ -1313,14 +1364,28 @@ impl Game<'_> {
     }
     /// The integrated server's owner into the world's player, for `Level::write`.
     pub(super) fn store_owner(&mut self) {
+        let Some(uuid) = self
+            .lan
+            .as_ref()
+            .and_then(|h| h.owner.as_ref())
+            .map(|o| o.uuid)
+        else {
+            return;
+        };
+        let riding = self.lan.as_ref().and_then(|h| {
+            h.hub
+                .guests
+                .iter()
+                .find(|g| g.uuid == uuid && g.placed)
+                .and_then(|g| g.vehicle)
+        });
+        // The vehicle the owner rides, by the UUID it is saved with.
+        let vehicle = self.root_vehicle_uuid(riding);
         let Some(host) = &self.lan else {
             return;
         };
-        let Some(uuid) = host.owner.as_ref().map(|o| o.uuid) else {
-            return;
-        };
         if let Some(g) = host.hub.guests.iter().find(|g| g.uuid == uuid && g.placed) {
-            playerdata::store(g, &mut self.level);
+            playerdata::store(g, &mut self.level, vehicle);
             self.save_guest_records(host, g);
         }
     }
@@ -1503,6 +1568,8 @@ impl Game<'_> {
                 m.rider = None;
             }
         }
+        // A guest whose file names the vehicle it rode rides it again.
+        self.restore_guest_vehicles(&mut host);
         // A dedicated server runs the hub without a host player.
         if state.is_some() || host.hub.config.dedicated {
             let has_guests = !host.hub.guests.is_empty();
@@ -1519,6 +1586,7 @@ impl Game<'_> {
                 self.lan_riding(host_entity, &guests, &mut host.hub.riding);
                 self.lan_entities(host_entity, &host.mob_players, &mut host.hub, &mut states);
                 self.lan_hook_states(host_entity, &host.play, &host.hub, &mut states);
+                self.lan_entity_uuids(&mut states);
             } else {
                 states.clear();
             }
@@ -1785,6 +1853,7 @@ impl Game<'_> {
             // A dedicated server has no host player.
             self.lan_entities(None, &host.mob_players, &mut host.hub, &mut theirs);
             self.lan_hook_states(None, &host.play, &host.hub, &mut theirs);
+            self.lan_entity_uuids(&mut theirs);
             theirs.as_slice()
         } else {
             entities
@@ -2008,6 +2077,34 @@ impl Game<'_> {
             }
             seen.insert(m.id, (m.hurt_time, dead, swing));
         }
+        // LivingEntity.hurtServer for a player: a hit that restarted the hurt
+        // time and was not blocked by a shield broadcasts the damage event,
+        // so the clients around (and the player's own) flash it red.
+        let host_player = self.player.as_ref().map(|p| {
+            (
+                host.host_entity,
+                [p.position.x, p.position.y, p.position.z],
+                p,
+            )
+        });
+        let guests = host.hub.guests.iter().filter(|g| host.hub.here(g));
+        let players: Vec<_> = host_player
+            .into_iter()
+            .chain(guests.filter_map(|g| g.motion.as_deref().map(|m| (g.entity_id, g.position, m))))
+            .map(|(id, at, p)| (id, at, p.health.hurt_animation_time, p.hurt_log.last()))
+            .collect();
+        for (id, at, hurt, record) in players {
+            let old = host
+                .mob_state
+                .get(&self.dim)
+                .and_then(|s| s.get(&(id as u32)));
+            if hurt > old.map_or(0, |o| o.0) {
+                // Starving keeps no record: any type flashes the same.
+                let kind = record.map_or("minecraft:generic", |r| r.source.as_str());
+                host.hub.damage_event(id, kind, None, None, at);
+            }
+            seen.insert(id as u32, (hurt, false, None));
+        }
         host.mob_state.insert(self.dim, seen);
         // Level.broadcastEntityEvent(player, 2) of a spear's stab.
         for attacker in kinetic_hits {
@@ -2116,11 +2213,13 @@ impl Game<'_> {
             m.limb_speed += ((dist * 4.0).min(1.0) - m.limb_speed) * 0.4;
             m.limb_position += m.limb_speed;
             m.age = m.age.wrapping_add(1);
-            m.extra.main_hand = g
-                .inventory
-                .get(g.selected)
-                .and_then(|s| s.as_ref())
-                .map(|s| s.item.clone());
+            // The hurt red flash (LivingEntity.hurtTime).
+            m.hurt_time = g
+                .motion
+                .as_ref()
+                .map_or(0, |p| p.health.hurt_animation_time);
+            m.extra
+                .set_main_hand_stack(g.inventory.get(g.selected).cloned().flatten());
             m.extra.off_hand = g.offhand.as_ref().map(|s| s.item.clone());
             [m.extra.head, m.extra.chest, m.extra.legs, m.extra.feet] = g
                 .armor

crates/horizon-client/src/game/lan_actions.rs

@@ -675,9 +675,7 @@ impl Game<'_> {
         let new_mode = self.mode_id();
         self.mode = mode;
         self.creative = creative;
-        self.selected = std::mem::replace(&mut g.selected, selected);
-        // `g.selected` now holds the host's value: swap the inventories back.
-        std::mem::swap(&mut self.selected, &mut g.selected);
+        g.selected = std::mem::replace(&mut self.selected, selected);
         std::mem::swap(&mut self.inventory, &mut g.inventory);
         std::mem::swap(&mut self.armor, &mut g.armor);
         std::mem::swap(&mut self.offhand, &mut g.offhand);
@@ -1877,8 +1875,11 @@ impl Game<'_> {
         // ListPlayersCommand needs no permission and lists every player.
         let words: Vec<&str> = command.trim_start_matches('/').split(' ').collect();
         if words[0] == "list" && (words.len() == 1 || words[1..] == ["uuids"]) {
-            let me = (self.options.dedicated.is_none() && self.player.is_some())
-                .then_some((host.host_uuid, host.host_name.as_str()));
+            // A single-player owner is a placed guest already: no host entry.
+            let me = (self.options.dedicated.is_none()
+                && self.player.is_some()
+                && host.hub.singleplayer_owner.is_none())
+            .then_some((host.host_uuid, host.host_name.as_str()));
             let content = host.hub.list_reply(me, words.len() == 2);
             host.hub.send_to(
                 conn,
@@ -2032,8 +2033,11 @@ impl Game<'_> {
         let d = vanilla::game_dispatcher();
         let level = std::mem::replace(&mut self.ui.registries.permission, permission);
         let parse = d.parse(command, &self.ui.registries);
-        let ((start, end), suggestions) = d.suggestions(&parse, command.len(), &self.ui.registries);
+        let ((start, end), mut suggestions) =
+            d.suggestions(&parse, command.len(), &self.ui.registries);
         self.ui.registries.permission = level;
+        // ServerCommandSuggestionsProvider.limitSuggestionCount.
+        suggestions.truncate(1000);
         let utf16 = |byte: usize| command[..byte.min(command.len())].encode_utf16().count() as i32;
         let mut w = horizon_protocol::buf::Writer::new();
         w.varint(id);
@@ -2361,14 +2365,25 @@ impl Game<'_> {
                     None => self.guest_death_message(conn, me),
                 };
                 let message = horizon_client::lan::data::component_nbt(&text.component());
-                let team = self.score.board.players_team(&name);
-                if horizon_client::scoreboard::own_death_message_shown(team) {
-                    host.hub.system_message(message.clone());
-                    if self.options.dedicated.is_some() {
+                let board = &self.score.board;
+                host.hub.system_message_to(message.clone(), |other| {
+                    horizon_client::scoreboard::death_message_reaches(board, &name, other)
+                });
+                if self.options.dedicated.is_some() {
+                    // Only a message for everyone is logged (`broadcastSystemMessage`).
+                    if board.players_team(&name).is_none_or(|t| {
+                        t.death_message_visibility == horizon_client::scoreboard::Visibility::Always
+                    }) {
                         super::dedicated::log("INFO", &format!("System chat: {}", text.plain()));
-                    } else if self.player.is_some() {
-                        self.system_message(text);
                     }
+                } else if self.player.is_some()
+                    && horizon_client::scoreboard::death_message_reaches(
+                        board,
+                        &name,
+                        super::chat::PLAYER_NAME,
+                    )
+                {
+                    self.system_message(text);
                 }
                 message
             } else {

crates/horizon-client/src/game/lan_attributes.rs

@@ -162,6 +162,22 @@ impl Game<'_> {
                 },
             );
         }
+        // LivingEntity.setSprinting: SPEED_MODIFIER_SPRINTING (a dashing cat or ocelot).
+        if let (true, Some(a)) = (
+            m.extra.sprinting,
+            self.synced_attribute(kind, "minecraft:movement_speed"),
+        ) {
+            add_modifier(
+                out,
+                a,
+                finalize::base_value(m, Attr::MovementSpeed),
+                AttributeModifier {
+                    id: "minecraft:sprinting".into(),
+                    amount: f64::from(0.3f32),
+                    operation: 2,
+                },
+            );
+        }
         let base = |name: &str| {
             Attr::ALL
                 .into_iter()

crates/horizon-client/src/game/lan_crafting.rs

@@ -129,8 +129,8 @@ impl Game<'_> {
         let dropped = std::mem::take(&mut menu.dropped);
         let equipped = std::mem::take(&mut menu.equipped);
         let brewed = std::mem::take(&mut menu.brewed);
+        let crafted = std::mem::take(&mut menu.crafted);
         menu.drops.clear();
-        menu.crafted.clear();
         store_player(menu, &mut host.hub.guests[gi]);
         if !brewed.is_empty() {
             let conn = host.hub.guests[gi].conn;
@@ -140,6 +140,14 @@ impl Game<'_> {
                 }
             });
         }
+        if !crafted.is_empty() {
+            let conn = host.hub.guests[gi].conn;
+            self.as_guest(host, conn, |g| {
+                for (recipe, ingredients) in &crafted {
+                    g.trigger_recipe_crafted(recipe, ingredients);
+                }
+            });
+        }
         if !equipped.is_empty() {
             let conn = host.hub.guests[gi].conn;
             self.as_guest(host, conn, |g| {

crates/horizon-client/src/game/lan_entities.rs

@@ -7,6 +7,7 @@ use super::Game;
 use horizon_client::lan::{
     entity::{EntityState, Riding, States},
     hub::Hub,
+    playerdata::ints_uuid,
 };
 use horizon_protocol::entity_data::{Value, serializer};
 use horizon_world::nbt::Tag;
@@ -167,6 +168,24 @@ impl Game<'_> {
                 e.meta.push((15, serializer::BYTE, Value::Byte(flags)));
             }
             e.meta.extend(stand_poses(a));
+            // Entity.DATA_CUSTOM_NAME and DATA_CUSTOM_NAME_VISIBLE: a hologram's text.
+            if let Some(name) = &a.custom_name {
+                e.meta.push((
+                    2,
+                    serializer::OPTIONAL_COMPONENT,
+                    Value::OptText(Some(horizon_client::scoreboard::json_to_tag(
+                        &name.component(),
+                    ))),
+                ));
+                if a.name_visible {
+                    e.meta.push((3, serializer::BOOLEAN, Value::Bool(true)));
+                }
+            }
+            // A name taken away or hidden again (`/data`) is sent as none / false.
+            e.defaults
+                .push((2, serializer::OPTIONAL_COMPONENT, Value::OptText(None)));
+            e.defaults
+                .push((3, serializer::BOOLEAN, Value::Bool(false)));
             // A pose put back to its default (`/data`) is sent as that default.
             e.defaults.push((15, serializer::BYTE, Value::Byte(0)));
             for (i, default) in horizon_client::entities::ArmorStand::DEFAULT_POSE
@@ -270,6 +289,16 @@ impl Game<'_> {
 }
 
 impl Game<'_> {
+    /// `ClientboundAddEntityPacket(Entity, ServerEntity, int)`: the entity's
+    /// own UUID (`Entity.getUUID`), the one `/data`, saves and UUID
+    /// selectors use, so a client can name it back (the crosshair UUID that
+    /// `ClientSuggestionProvider.getSelectedEntities` suggests).
+    pub(super) fn lan_entity_uuids(&mut self, states: &mut States) {
+        for e in states.as_mut_slice() {
+            e.uuid = ints_uuid(self.uuid_for(e.id as u32));
+        }
+    }
+
     /// Gives the entities Horizon keeps without an id one (`Entity.id`, from
     /// the same counter as the rest) before they are first tracked.
     pub(super) fn lan_assign_ids(&mut self) {

crates/horizon-client/src/game/lan_screen.rs

@@ -959,6 +959,7 @@ impl Game<'_> {
         };
         let ctrl = self.keys.contains(&winit::keyboard::KeyCode::ControlLeft);
         let shortcut = self.edit_shortcut(event);
+        let types_text = self.types_text();
         let Some(o) = self.world_options.as_mut() else {
             return;
         };
@@ -970,7 +971,7 @@ impl Game<'_> {
                 None => {
                     let mut handled = false;
                     rules.edit(|b| handled = b.key(key, ctrl, false));
-                    if !handled && !ctrl {
+                    if !handled && types_text {
                         self.world_options_text(event.text.as_deref());
                     }
                 }
@@ -984,7 +985,7 @@ impl Game<'_> {
             o.port.shortcut(shortcut, &mut self.clipboard);
             return;
         }
-        if !o.port.key(key, ctrl, false) && !ctrl {
+        if !o.port.key(key, ctrl, false) && types_text {
             self.world_options_text(event.text.as_deref());
         }
     }

crates/horizon-client/src/game/maps.rs

@@ -1308,7 +1308,7 @@ impl Game<'_> {
         }
     }
     /// `renderTwoHandedMap`: map `id` held in both hands, in view space (the
-    /// arms under it are not drawn).
+    /// arms under it: `first_person::map_arm_poses`).
     pub(super) fn two_handed_map_geometry(
         &mut self,
         to_world: glam::Mat4,
@@ -1318,22 +1318,11 @@ impl Game<'_> {
         light: u32,
         out: &mut Vec<Vertex>,
     ) {
+        use horizon_core::geometry::trig::Mth;
         let deg = |d: f32| d.to_radians();
-        let sqrt_attack = attack.sqrt();
-        let y_swing = -0.2 * (attack * std::f32::consts::PI).sin();
-        let z_swing = -0.4 * (sqrt_attack * std::f32::consts::PI).sin();
-        // calculateMapTilt
-        let tilt = (1.0 - self.pitch / 45.0 + 0.1).clamp(0.0, 1.0);
-        let tilt = -(tilt * std::f32::consts::PI).cos() * 0.5 + 0.5;
         let base = to_world
-            * glam::Mat4::from_translation(glam::Vec3::new(0.0, -y_swing / 2.0, z_swing))
-            * glam::Mat4::from_translation(glam::Vec3::new(
-                0.0,
-                0.04 + inverse_height * -1.2 + tilt * -0.5,
-                -0.72,
-            ))
-            * glam::Mat4::from_rotation_x(deg(tilt * -85.0));
-        let swing = (sqrt_attack * std::f32::consts::PI).sin();
+            * horizon_client::first_person::two_handed_map_base(self.pitch, inverse_height, attack);
+        let swing = (attack.sqrt() * std::f32::consts::PI).msin();
         let m = base
             * glam::Mat4::from_rotation_x(deg(swing * 20.0))
             * glam::Mat4::from_scale(glam::Vec3::splat(2.0));

crates/horizon-client/src/game/minecarts.rs

@@ -1028,6 +1028,17 @@ impl Game<'_> {
         }
         best
     }
+    /// `ContainerEntity.unpackChestVehicleLootTable` for a player who opens a
+    /// chest minecart: a roll it still holds fires `player_generates_container_loot`
+    /// for its table, and the cart keeps its items from then on.
+    fn unpack_cart_loot(&mut self, i: usize) {
+        let Some(loot) = self.carts[i].loot.take() else {
+            return;
+        };
+        if loot.items == horizon_client::save::encode_items(&self.carts[i].items) {
+            self.trigger_loot_table(&loot.table);
+        }
+    }
     /// `interact`: ride, open, fuel or ignite the cart under the crosshair.
     pub(super) fn interact_cart(&mut self) -> bool {
         let Some((i, d)) = self.cart_hit() else {
@@ -1047,6 +1058,7 @@ impl Game<'_> {
             }
             // AbstractMinecartContainer.interact: no sneak check.
             CartKind::Chest | CartKind::Hopper => {
+                self.unpack_cart_loot(i);
                 let c = self.carts[i].clone();
                 let key = (i32::MAX - 15, CART_KEY_Y, c.id as i32);
                 self.world
@@ -1227,6 +1239,37 @@ impl Game<'_> {
         light: u32,
         diffuse: bool,
         out: &mut Vec<Vertex>,
+    ) {
+        self.tinted_block_model_vertices(state, seed, m, |_| light, diffuse, |_| None, out);
+    }
+    /// `block_model_vertices` with `tint` (RGB) on the faces that have a tint index.
+    #[allow(clippy::too_many_arguments)]
+    pub(super) fn block_model_vertices_tinted(
+        &self,
+        state: BlockStateId,
+        seed: i64,
+        m: glam::Mat4,
+        light: u32,
+        diffuse: bool,
+        tint: u32,
+        out: &mut Vec<Vertex>,
+    ) {
+        let tint = |index: i32| (index >= 0).then_some(tint);
+        self.tinted_block_model_vertices(state, seed, m, |_| light, diffuse, tint, out);
+    }
+    /// `block_model_vertices` with each face multiplied by `tint` of its
+    /// tint index (RGB, `None` for untinted faces) and lit by `light` of
+    /// each quad.
+    #[allow(clippy::too_many_arguments)]
+    pub(super) fn tinted_block_model_vertices(
+        &self,
+        state: BlockStateId,
+        seed: i64,
+        m: glam::Mat4,
+        light: impl Fn(&horizon_assets::bake::ModelQuad) -> u32,
+        diffuse: bool,
+        tint: impl Fn(i32) -> Option<u32>,
+        out: &mut Vec<Vertex>,
     ) {
         let Ok(models) = self.pack.render.model_catalog.collect_seeded(state, seed) else {
             return;
@@ -1248,11 +1291,17 @@ impl Game<'_> {
                     D::North | D::South => 204,
                     D::West | D::East => 153,
                 };
-                let color = if diffuse {
+                let mut color = if diffuse {
                     u32::MAX
                 } else {
                     0xFF00_0000 | shade << 16 | shade << 8 | shade
                 };
+                if let Some(t) = tint(face.quad.tint_index) {
+                    color = horizon_client::hud_layout::multiply(
+                        color,
+                        horizon_client::mobs::render::abgr(t),
+                    );
+                }
                 let normal = if diffuse {
                     use horizon_client::item_render::{direction_vector, transform_normal};
                     let n = transform_normal(m, direction_vector(face.quad.facing));
@@ -1261,6 +1310,7 @@ impl Game<'_> {
                 } else {
                     [0; 4]
                 };
+                let light = light(&face.quad);
                 let light = if diffuse {
                     let emission = u32::from(face.quad.light_emission) * 16;
                     (light & 0xFF) | (light >> 8 & 0xFF).max(emission) << 8