Merge remote-tracking branch 'origin/main' into fix-3153

Co-Authored-By: Claude Opus 5.5 <[email protected]>

.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"). -->

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
         run: |
           cargo +stable fmt --all -- --check
           # With the game's code mods (on in every release build, off by default).
-          cargo +stable clippy --workspace --all-targets --features horizon-client/mods -- -D warnings
+          cargo +stable clippy --workspace --all-targets -- -D warnings
           # The server build (released as horizon-engine): the game without sound or controllers.
           cargo +stable clippy -p horizon-client --all-targets --no-default-features -- -D warnings
       # Libraries, binaries and integration tests, then doc tests: not the ~275 examples, which clippy above already
@@ -71,11 +71,11 @@ jobs:
       - name: Test Rust core and voxel kernel correctness
         if: steps.rust.outputs.required != 'false'
         run: |
-          cargo +stable test --workspace --lib --bins --tests --features horizon-client/mods,horizon-mods/pack
+          cargo +stable test --workspace --lib --bins --tests --features horizon-mods/pack
           # The full content-root tests (#[ignore]d: minutes each on a laptop). The same build as above; they need the
           # prepared vanilla data, so without it they pass at once.
-          cargo +stable test --workspace --lib --features horizon-client/mods,horizon-mods/pack mod_content::tests:: -- --ignored
-          cargo +stable test --workspace --doc --features horizon-client/mods,horizon-mods/pack
+          cargo +stable test --workspace --lib --features horizon-mods/pack mod_content::tests:: -- --ignored
+          cargo +stable test --workspace --doc --features horizon-mods/pack
   # The launcher is its own workspace (launcher/Cargo.toml), so verify's cargo runs never build it. A pull request that
   # changes it or a crate it builds is checked here, and so is every push to main: two pull requests can each pass
   # alone and break it together (#2059 and the registry ratings did, 2026-10-26).

.github/workflows/game-build.yml

@@ -138,8 +138,7 @@ jobs:
         if: runner.os == 'Linux'
         run: sudo apt-get update && sudo apt-get install -y --no-install-recommends libasound2-dev libudev-dev
       - name: Build the client, horizon-ctl, horizon-prepare and horizon-server
-        # `horizon-client/mods`: every released game runs code mods (the feature is off in dev builds).
-        run: cargo build --release --locked --features horizon-client/mods -p horizon-client --bin horizon-client --bin horizon-ctl -p horizon-prepare --bin horizon-prepare -p horizon-server --bin horizon-server
+        run: cargo build --release --locked -p horizon-client --bin horizon-client --bin horizon-ctl -p horizon-prepare --bin horizon-prepare -p horizon-server --bin horizon-server
       - name: Every program the release folder takes was built
         run: |
           for binary in horizon-client horizon-ctl horizon-prepare horizon-server; do
@@ -267,9 +266,8 @@ jobs:
         run: |
           set -euo pipefail
           # After the client is packaged: target/release/horizon-client is rebuilt without the audio and
-          # controllers features, so it needs neither libasound nor libudev (minimal server images lack them),
-          # and with code mods like the client.
-          cargo build --release --locked -p horizon-client --no-default-features --features mods --bin horizon-client
+          # controllers features, so it needs neither libasound nor libudev (minimal server images lack them).
+          cargo build --release --locked -p horizon-client --no-default-features --bin horizon-client
           cargo run --locked -p xtask -- package-server target/release/horizon-client "dist/${{ matrix.server_dir }}"
           folder="dist/${{ matrix.server_dir }}"
           python3 tools/check_imports.py --server "$folder/horizon-engine" "$folder/horizon-server" "$folder/horizon-prepare"

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
@@ -74,7 +76,7 @@ cargo build --profile fast -p horizon-client        # optimized, quick to link:
 python3 tools/parity.py --changed origin/main       # the harnesses your branch can affect (CI's parity job)
 python3 tools/parity.py --changed-files paths.txt --list   # which harnesses cover these files, without running them
 python3 tools/parity.py mob_ai sculk       # named harnesses
-python3 tools/lan_e2e.py --check chest     # two real games over LAN (server-thread host); --in-frame compares the fallback
+python3 tools/lan_e2e.py --check chest     # two real games over LAN (server-thread host)
 python3 tools/agent_control_e2e.py         # horizon-ctl / MCP end to end
 ```
 
@@ -167,17 +169,18 @@ the same `horizon_client::<module>` paths), `G:` = bin (`crates/horizon-client/s
    "Server thread" with one level per dimension; the window joins it as a client through memory (`remote`),
    exactly as a LAN guest or a dedicated server's player does. This is what players run. Open
    `[server-thread]` issues list the gaps left.
-2. **In-frame (`--in-frame`, `--no-server-thread` or `HORIZON_SERVER_THREAD=0`):** the window's `Game` ticks
-   the world itself, one level that follows the player (`fn enter_dimension`). Deterministic rule fixtures still use this path; player-facing integration uses the default server thread.
+2. **In-frame (`--in-frame`, `--no-server-thread` or `HORIZON_SERVER_THREAD=0`): DEPRECATED, never use it, it
+   will be removed soon.** The window's `Game` ticks the world itself, one level that follows the player
+   (`fn enter_dimension`). Compatibility does not matter: don't add features or fixes for it, don't write new
+   tests against it, and move code off it when you touch it. The deterministic rule fixtures still run on it
+   until they are ported.
 
-LAN guests and dedicated servers always use the server code, so a fix there serves both. Test both paths
-when you touch player-facing gameplay:
+LAN guests and dedicated servers always use the server code, so a fix there serves both. Test the server
+thread when you touch player-facing gameplay:
 
 ```sh
 cargo run --profile fast -p horizon-client -- --resources .local/horizon-client/26.3 --world T               # server thread
-cargo run --profile fast -p horizon-client -- --resources .local/horizon-client/26.3 --world T --in-frame    # in-frame
 python3 tools/lan_e2e.py --check <name>                  # host on its server thread, guest is a server client
-python3 tools/lan_e2e.py --in-frame --check <name>       # comparison (portals, levels, distance, lava need server-thread mode)
 python3 tools/parity.py dedicated_server server_entities server_player_damage
 ```
 

Cargo.lock

@@ -1527,6 +1527,9 @@ name = "horizon-hdr"
 version = "0.1.0"
 dependencies = [
  "ash",
+ "wayland-backend",
+ "wayland-client",
+ "wayland-protocols",
  "wgpu",
 ]
 

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 +269,11 @@ 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"));
+        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/potions.rs

@@ -91,6 +91,7 @@ pub fn effect(id: &str) -> Option<&'static EffectDef> {
 /// Namespaced effect ids for mob effect storage.
 pub fn namespaced(id: &'static str) -> &'static str {
     static IDS: OnceLock<HashMap<&'static str, &'static str>> = OnceLock::new();
+    let key = id.strip_prefix("minecraft:").unwrap_or(id);
     IDS.get_or_init(|| {
         EFFECTS
             .iter()
@@ -102,7 +103,7 @@ pub fn namespaced(id: &'static str) -> &'static str {
             })
             .collect()
     })
-    .get(id)
+    .get(key)
     .copied()
     .unwrap_or(id)
 }

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-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/audio.rs

@@ -144,6 +144,7 @@ type Stream = cpal::Stream;
 type Stream = std::convert::Infallible;
 pub struct Audio {
     _stream: Option<Stream>,
+    device_name: String,
     pub engine: SoundEngine,
     backend: MixerBackend,
     /// Record `Heard` sounds (the subtitle overlay is listening).
@@ -543,15 +544,48 @@ fn build_stream<T: cpal::SizedSample + cpal::FromSample<f32>>(
     )?;
     Ok(stream)
 }
+/// Available audio output device names.
+#[cfg(feature = "audio")]
+pub fn output_devices() -> Vec<String> {
+    if output_disabled(|name| std::env::var_os(name)).is_some() {
+        return Vec::new();
+    }
+    let host = cpal::default_host();
+    let mut names = Vec::new();
+    if let Ok(devices) = host.output_devices() {
+        for device in devices {
+            if let Ok(name) = device.name()
+                && !names.contains(&name)
+            {
+                names.push(name);
+            }
+        }
+    }
+    names
+}
+
+#[cfg(not(feature = "audio"))]
+pub fn output_devices() -> Vec<String> {
+    Vec::new()
+}
+
 impl Audio {
     pub fn new(root: &Path) -> Self {
-        Self::with_output(root, true)
+        Self::with_device(root, "")
+    }
+    pub fn with_device(root: &Path, device_name: &str) -> Self {
+        Self::with_output(root, true, device_name)
     }
     /// No output device: the dedicated server.
     pub fn silent(root: &Path) -> Self {
-        Self::with_output(root, false)
+        Self::with_output(root, false, "")
     }
-    fn with_output(root: &Path, output: bool) -> Self {
+    /// The output device asked for (`soundDevice`), empty for the system's default; the
+    /// default plays when that one can't be opened, as in vanilla.
+    pub fn device(&self) -> &str {
+        &self.device_name
+    }
+    fn with_output(root: &Path, output: bool, target_device: &str) -> Self {
         let registry = SoundRegistry::load(root);
         if output && registry.is_empty() {
             // The game then plays nothing on a working output (#1035, #1076).
@@ -564,7 +598,7 @@ impl Audio {
         }
         let mixer = Arc::new(Mutex::new(Mixer::default()));
         let opened = if output {
-            Self::open(mixer.clone())
+            Self::open_named(mixer.clone(), target_device)
         } else {
             Err("no output on a dedicated server".into())
         };
@@ -581,6 +615,7 @@ impl Audio {
         engine.loaded = live;
         Self {
             _stream: stream,
+            device_name: target_device.to_owned(),
             engine,
             backend: MixerBackend {
                 mixer,
@@ -602,10 +637,61 @@ impl Audio {
         }
     }
     #[cfg(not(feature = "audio"))]
-    fn open(_: Arc<Mutex<Mixer>>) -> Result<Stream> {
+    fn open_named(_: Arc<Mutex<Mixer>>, _: &str) -> Result<Stream> {
         Err("this build has no sound output (built without the `audio` feature)".into())
     }
     #[cfg(feature = "audio")]
+    fn open_named(mixer: Arc<Mutex<Mixer>>, target: &str) -> Result<Stream> {
+        if let Some(reason) = output_disabled(|name| std::env::var_os(name)) {
+            return Err(reason.into());
+        }
+        let host = cpal::default_host();
+        if !target.is_empty()
+            && let Ok(devices) = host.output_devices()
+        {
+            for device in devices {
+                let name = device.name().unwrap_or_else(|_| "unnamed device".into());
+                if name == target {
+                    match open_device(&device, mixer.clone()) {
+                        Ok((stream, config)) => {
+                            log::info!(
+                                "Horizon: audio output {name} ({} Hz, {} channels, {})",
+                                config.sample_rate().0,
+                                config.channels(),
+                                config.sample_format()
+                            );
+                            return Ok(stream);
+                        }
+                        Err(e) => {
+                            log::warn!(
+                                "Horizon: could not open audio device '{target}': {e}; falling back to default"
+                            );
+                        }
+                    }
+                    break;
+                }
+            }
+        }
+        Self::open(mixer)
+    }
+    #[cfg(feature = "audio")]
+    pub fn set_device(&mut self, name: &str) -> Result<()> {
+        if !self.backend.live && self._stream.is_none() && !self.engine.loaded {
+            self.device_name = name.to_owned();
+            return Ok(());
+        }
+        self._stream = Some(Self::open_named(self.backend.mixer.clone(), name)?);
+        self.device_name = name.to_owned();
+        self.backend.live = true;
+        self.engine.loaded = true;
+        Ok(())
+    }
+    #[cfg(not(feature = "audio"))]
+    pub fn set_device(&mut self, name: &str) -> Result<()> {
+        self.device_name = name.to_owned();
+        Ok(())
+    }
+    #[cfg(feature = "audio")]
     fn open(mixer: Arc<Mutex<Mixer>>) -> Result<Stream> {
         if let Some(reason) = output_disabled(|name| std::env::var_os(name)) {
             return Err(reason.into());

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

@@ -653,6 +653,42 @@ pub struct Commands<'a> {
     pub registries: &'a Registries,
 }
 
+/// `CommandSuggestions`' constructor arguments: how a screen's suggestions
+/// parse and where they are drawn.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct SuggestLayout {
+    /// `commandsOnly`: the input is a command without a leading `/`.
+    pub commands_only: bool,
+    /// `onlyShowIfCursorPastError`: completions from the command's start,
+    /// not only past the `/`.
+    pub only_past_error: bool,
+    /// `suggestionLineLimit`.
+    pub line_limit: usize,
+    /// `anchorToBottom`: the list and usage over a box at the bottom, else
+    /// under one at the top (y 72).
+    pub anchor_to_bottom: bool,
+    /// `fillColor`: behind the list and the usage lines.
+    pub fill: i32,
+}
+impl SuggestLayout {
+    /// ChatScreen.init's `CommandSuggestions`.
+    pub const CHAT: Self = Self {
+        commands_only: false,
+        only_past_error: false,
+        line_limit: 10,
+        anchor_to_bottom: true,
+        fill: FILL,
+    };
+    /// AbstractCommandBlockEditScreen.init's `CommandSuggestions`.
+    pub const COMMAND_BLOCK: Self = Self {
+        commands_only: true,
+        only_past_error: true,
+        line_limit: 7,
+        anchor_to_bottom: false,
+        fill: i32::MIN,
+    };
+}
+
 /// The open chat screen: vanilla's `ChatScreen` with its `EditBox` and
 /// `CommandSuggestions` (argument colouring, usage lines, parse errors,
 /// the suggestion list, Tab completion, history).
@@ -680,6 +716,7 @@ pub struct ChatScreen {
     pub auto_suggestions: bool,
     /// `CommandSuggestions.setRestrictions`: what the Chat option allows.
     pub abilities: ChatAbilities,
+    pub layout: SuggestLayout,
 }
 /// Local completions waiting for the server's reply to request `id`.
 struct Awaiting {
@@ -750,6 +787,43 @@ impl ChatScreen {
             keep_suggestions: false,
             auto_suggestions: true,
             abilities,
+            layout: SuggestLayout::CHAT,
+        };
+        s.update_command_info(m, c);
+        s
+    }
+    /// `AbstractCommandBlockEditScreen.init`: the command box at the top,
+    /// focused, holding `command`, with suggestions from the start.
+    pub fn command_block(
+        m: &Measure,
+        c: &Commands,
+        command: &str,
+        width: i32,
+        height: i32,
+    ) -> Self {
+        let mut input = TextField::new(width / 2 - 150, 50, 300, 20);
+        input.max_length = 32500;
+        input.focused = true;
+        input.set_value(m, command);
+        let mut s = Self {
+            input,
+            width,
+            height,
+            history_buffer: String::new(),
+            history_pos: 0,
+            parse: None,
+            pending: None,
+            awaiting: None,
+            request: None,
+            suggestions: None,
+            usage: Vec::new(),
+            usage_position: 0,
+            usage_width: 0,
+            allow_suggestions: true,
+            keep_suggestions: false,
+            auto_suggestions: true,
+            abilities: ChatAbilities::new(ChatVisibility::Full),
+            layout: SuggestLayout::COMMAND_BLOCK,
         };
         s.update_command_info(m, c);
         s
@@ -768,7 +842,11 @@ impl ChatScreen {
             let value = self.input.value.clone();
             let auto = self.auto_suggestions;
             let abilities = self.abilities;
-            *self = Self::new(m, c, &value, self.history_pos, width, height, abilities);
+            *self = if self.layout == SuggestLayout::CHAT {
+                Self::new(m, c, &value, self.history_pos, width, height, abilities)
+            } else {
+                Self::command_block(m, c, &value, width, height)
+            };
             self.auto_suggestions = auto;
         }
     }
@@ -814,11 +892,18 @@ impl ChatScreen {
         self.usage.clear();
         let cursor = self.input.cursor;
         let cursor_b = byte_at(&command, cursor);
-        if command.starts_with('/') {
+        let slash = command.starts_with('/');
+        if self.layout.commands_only || slash {
+            let start = usize::from(slash);
             if self.parse.is_none() {
-                self.parse = Some(c.dispatcher.parse_at(&command, 1, c.registries));
+                self.parse = Some(c.dispatcher.parse_at(&command, start, c.registries));
             }
-            if cursor >= 1 && (self.suggestions.is_none() || !self.keep_suggestions) {
+            let from = if self.layout.only_past_error {
+                start
+            } else {
+                1
+            };
+            if cursor >= from && (self.suggestions.is_none() || !self.keep_suggestions) {
                 let parse = self.parse.as_ref().expect("parsed above");
                 let (range, list, ask) =
                     c.dispatcher
@@ -1002,7 +1087,11 @@ impl ChatScreen {
             0,
             self.input.screen_x(m, 0) + self.input.inner_width() - width,
         );
-        let y = self.height - 12;
+        let y = if self.layout.anchor_to_bottom {
+            self.height - 12
+        } else {
+            72
+        };
         // sortSuggestions: those starting with the word at the cursor first.
         let partial = &value[..byte_at(&value, self.input.cursor)];
         let word = partial[last_word_index(partial)..].to_lowercase();
@@ -1011,9 +1100,16 @@ impl ChatScreen {
                 s.text.starts_with(&word) || s.text.starts_with(&format!("minecraft:{word}"))
             });
         first.extend(rest);
-        let n = first.len().min(10) as i32;
+        // SuggestionsList: beside a bordered box, or over an unbordered one.
+        let n = first.len().min(self.layout.line_limit) as i32;
+        let bordered = i32::from(self.input.bordered);
+        let top = if self.layout.anchor_to_bottom {
+            y - 3 - n * 12
+        } else {
+            y - bordered
+        };
         let mut l = SuggestionList {
-            rect: [x - 1, y - 3 - n * 12, width + 1, n * 12],
+            rect: [x - (1 - bordered), top, width + 1, n * 12],
             original: value,
             list: first,
             offset: 0,
@@ -1042,11 +1138,12 @@ impl ChatScreen {
     }
     fn cycle(&mut self, l: &mut SuggestionList, dir: isize) {
         self.select(l, l.current as isize + dir);
-        let max = l.list.len().saturating_sub(10);
+        let limit = self.layout.line_limit;
+        let max = l.list.len().saturating_sub(limit);
         if l.current < l.offset {
             l.offset = l.current.min(max);
-        } else if l.current > l.offset + 9 {
-            l.offset = (l.current as isize + 1 - 10).clamp(0, max as isize) as usize;
+        } else if l.current >= l.offset + limit {
+            l.offset = (l.current as isize + 1 - limit as isize).clamp(0, max as isize) as usize;
         }
     }
     /// `SuggestionsList.useSuggestion`.
@@ -1074,7 +1171,57 @@ impl ChatScreen {
         ctrl: bool,
     ) -> ChatAction {
         use winit::keyboard::KeyCode as K;
-        // CommandSuggestions.keyPressed.
+        if self.suggestions_key(m, c, key, shift) {
+            return ChatAction::None;
+        }
+        match key {
+            K::Escape => return ChatAction::Close,
+            K::Enter | K::NumpadEnter => {
+                // ChatScreen.keyPressed: without `hasAllowedInput` the input
+                // stays, unsent, and the screen stays open.
+                if !self.abilities.allows(&self.input.value) {
+                    return ChatAction::None;
+                }
+                return ChatAction::Submit(self.normalized());
+            }
+            K::ArrowUp => self.move_in_history(m, c, history, -1),
+            K::ArrowDown => self.move_in_history(m, c, history, 1),
+            _ => {
+                self.field_key(m, c, key, shift, ctrl);
+            }
+        }
+        ChatAction::None
+    }
+    /// The input box's own keys (`EditBox.keyPressed`), the suggestions
+    /// following an edit: whether the box took the key.
+    pub fn field_key(
+        &mut self,
+        m: &Measure,
+        c: &Commands,
+        key: winit::keyboard::KeyCode,
+        shift: bool,
+        ctrl: bool,
+    ) -> bool {
+        match self.input.key(m, key, shift, ctrl) {
+            Some(changed) => {
+                if changed {
+                    self.edited(m, c);
+                }
+                true
+            }
+            None => false,
+        }
+    }
+    /// `CommandSuggestions.keyPressed`: the list's arrows, Tab and Escape,
+    /// and Tab to show it. True when the suggestions took the key.
+    pub fn suggestions_key(
+        &mut self,
+        m: &Measure,
+        c: &Commands,
+        key: winit::keyboard::KeyCode,
+        shift: bool,
+    ) -> bool {
+        use winit::keyboard::KeyCode as K;
         if let Some(mut l) = self.suggestions.take() {
             let handled = match key {
                 K::ArrowUp | K::ArrowDown => {
@@ -1091,37 +1238,18 @@ impl ChatScreen {
                 }
                 K::Escape => {
                     self.input.suggestion = None;
-                    return ChatAction::None;
+                    return true;
                 }
                 _ => false,
             };
             self.suggestions = Some(l);
-            if handled {
-                return ChatAction::None;
-            }
+            handled
         } else if key == K::Tab {
             self.show_suggestions(m);
-            return ChatAction::None;
+            true
+        } else {
+            false
         }
-        match key {
-            K::Escape => return ChatAction::Close,
-            K::Enter | K::NumpadEnter => {
-                // ChatScreen.keyPressed: without `hasAllowedInput` the input
-                // stays, unsent, and the screen stays open.
-                if !self.abilities.allows(&self.input.value) {
-                    return ChatAction::None;
-                }
-                return ChatAction::Submit(self.normalized());
-            }
-            K::ArrowUp => self.move_in_history(m, c, history, -1),
-            K::ArrowDown => self.move_in_history(m, c, history, 1),
-            _ => {
-                if self.input.key(m, key, shift, ctrl) == Some(true) {
-                    self.edited(m, c);
-                }
-            }
-        }
-        ChatAction::None
     }
     /// `ChatScreen.moveInHistory`.
     fn move_in_history(&mut self, m: &Measure, c: &Commands, history: &[String], dir: isize) {
@@ -1175,7 +1303,7 @@ impl ChatScreen {
         if !l.contains(mouse.0, mouse.1) {
             return false;
         }
-        let max = l.list.len().saturating_sub(10) as i32;
+        let max = l.list.len().saturating_sub(self.layout.line_limit) as i32;
         l.offset = ((l.offset as f64 - amount.clamp(-1.0, 1.0)) as i32).clamp(0, max) as usize;
         true
     }
@@ -1246,7 +1374,9 @@ impl ChatScreen {
     ) -> Vec<Draw> {
         let (w, h) = (self.width, self.height);
         let mut out = Vec::new();
-        d::fill(&mut out, 2, h - 14, w - 2, h - 2, background);
+        if self.layout.anchor_to_bottom {
+            d::fill(&mut out, 2, h - 14, w - 2, h - 2, background);
+        }
         let format = |s: &str, o: usize| self.format(s, o);
         self.input.draw(&mut out, m, blink_ms, Some(&format));
         if let Some(mut l) = self.suggestions.take() {
@@ -1254,14 +1384,18 @@ impl ChatScreen {
             self.suggestions = Some(l);
         } else {
             for (i, line) in self.usage.iter().enumerate() {
-                let y = h - 27 - 12 * i as i32;
+                let y = if self.layout.anchor_to_bottom {
+                    h - 27 - 12 * i as i32
+                } else {
+                    72 + 12 * i as i32
+                };
                 d::fill(
                     &mut out,
                     self.usage_position - 1,
                     y,
                     self.usage_position + self.usage_width + 1,
                     y + 12,
-                    FILL,
+                    self.layout.fill,
                 );
                 d::text(&mut out, line.clone(), self.usage_position, y + 2, -1, true);
             }
@@ -1275,7 +1409,7 @@ impl ChatScreen {
         l: &mut SuggestionList,
         mouse: (i32, i32),
     ) {
-        let limit = l.list.len().min(10);
+        let limit = l.list.len().min(self.layout.line_limit);
         let [rx, ry, rw, rh] = l.rect;
         let has_prev = l.offset > 0;
         let has_next = l.list.len() > l.offset + limit;
@@ -1284,8 +1418,8 @@ impl ChatScreen {
             l.last_mouse = mouse;
         }
         if has_prev || has_next {
-            d::fill(out, rx, ry - 1, rx + rw, ry, FILL);
-            d::fill(out, rx, ry + rh, rx + rw, ry + rh + 1, FILL);
+            d::fill(out, rx, ry - 1, rx + rw, ry, self.layout.fill);
+            d::fill(out, rx, ry + rh, rx + rw, ry + rh + 1, self.layout.fill);
             if has_prev {
                 for x in (0..rw).step_by(2) {
                     d::fill(out, rx + x, ry - 1, rx + x + 1, ry, -1);
@@ -1300,7 +1434,7 @@ impl ChatScreen {
         let mut hovered = false;
         for i in 0..limit {
             let y = ry + 12 * i as i32;
-            d::fill(out, rx, y, rx + rw, y + 12, FILL);
+            d::fill(out, rx, y, rx + rw, y + 12, self.layout.fill);
             if mouse.0 > rx && mouse.0 < rx + rw && mouse.1 > y && mouse.1 < y + 12 {
                 if moved {
                     self.select(l, (i + l.offset) as isize);

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

@@ -486,6 +486,24 @@ pub fn create_experience(
     xp
 }
 
+/// The `MenuType` the block entity of a one-block storage container opens
+/// (`createMenu`): `ChestMenu.threeRows` for chests, trapped and copper chests
+/// and barrels, `ShulkerBoxMenu` for shulker boxes of any colour (its
+/// `ShulkerBoxSlot`s refuse shulker boxes), `DispenserMenu` for dispensers
+/// and droppers, `HopperMenu` for hoppers. None for other blocks.
+pub fn block_menu_type(block: &str) -> Option<&'static str> {
+    Some(match block {
+        "minecraft:chest" | "minecraft:trapped_chest" | "minecraft:barrel" => {
+            "minecraft:generic_9x3"
+        }
+        n if n.ends_with("copper_chest") => "minecraft:generic_9x3",
+        n if n.ends_with("shulker_box") => "minecraft:shulker_box",
+        "minecraft:dispenser" | "minecraft:dropper" => "minecraft:generic_3x3",
+        "minecraft:hopper" => "minecraft:hopper",
+        _ => return None,
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

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());
@@ -327,13 +373,16 @@ pub fn report_watchdog(home: &Path, side: &'static str, message: String) -> Opti
     )
 }
 
-fn panic_message(info: &std::panic::PanicHookInfo) -> String {
-    let payload = info.payload();
-    let text = payload
+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}"),
@@ -436,10 +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 {
@@ -628,6 +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/extras.rs

@@ -72,9 +72,8 @@ pub struct Extras {
     pub zoom_smooth: bool,
     /// Divide mouse turning by the zoom.
     pub zoom_sensitivity: bool,
-    /// The FPS counter and keystrokes extras are official mods now
-    /// (`moved_extras`): their old settings stay here until the game has
-    /// installed the mod for a player who had one on.
+    /// The FPS counter and keystrokes extras are official mods now: their
+    /// old settings stay here, kept as they were.
     pub fps: bool,
     pub fps_corner: Corner,
     /// Also show the minimum and 1% low.
@@ -83,8 +82,8 @@ pub struct Extras {
     pub keystrokes_corner: Corner,
     /// Clicks per second under the mouse buttons.
     pub keystrokes_cps: bool,
-    /// The official mods installed for the extras they replace, by mod id
-    /// (`movedToMods`): each is done once.
+    /// The official mods once installed for the extras they replace, by mod
+    /// id (`movedToMods`).
     pub moved: Vec<String>,
     pub minimap: bool,
     pub minimap_corner: Corner,
@@ -97,6 +96,8 @@ pub struct Extras {
     pub minimap_rotate: bool,
     /// Retry lost multiplayer connections (`reconnect`).
     pub auto_reconnect: bool,
+    /// The player's own name tag over its model in third person.
+    pub own_name_tag: bool,
     /// Mouse Tweaks-style drags in the inventory and storage containers.
     pub mouse_tweaks: bool,
     /// With them, the wheel over a slot moves its items one at a time.
@@ -137,6 +138,7 @@ impl Default for Extras {
             minimap_zoom: 1.0,
             minimap_rotate: false,
             auto_reconnect: false,
+            own_name_tag: false,
             mouse_tweaks: false,
             mouse_tweaks_wheel: true,
             sort: false,
@@ -211,6 +213,7 @@ impl Extras {
                 }
                 "minimapRotate" => e.minimap_rotate = flag(e.minimap_rotate),
                 "autoReconnect" => e.auto_reconnect = flag(e.auto_reconnect),
+                "ownNameTag" => e.own_name_tag = flag(e.own_name_tag),
                 "mouseTweaks" => e.mouse_tweaks = flag(e.mouse_tweaks),
                 "mouseTweaksWheel" => e.mouse_tweaks_wheel = flag(e.mouse_tweaks_wheel),
                 "sort" => e.sort = flag(e.sort),
@@ -225,7 +228,7 @@ impl Extras {
     }
     pub fn serialize(&self) -> String {
         format!(
-            "fullbright:{}\ndynamicLights:{}\nzoom:{}\nzoomKey:{}\nzoomLevel:{}\nzoomSmooth:{}\nzoomSensitivity:{}\nfps:{}\nfpsCorner:{}\nfpsLows:{}\nkeystrokes:{}\nkeystrokesCorner:{}\nkeystrokesCps:{}\nmovedToMods:{}\nminimap:{}\nminimapCorner:{}\nminimapSize:{}\nminimapShape:{}\nminimapZoom:{}\nminimapRotate:{}\nautoReconnect:{}\nmouseTweaks:{}\nmouseTweaksWheel:{}\nsort:{}\nsortKey:{}\n{}:{}\nagentControl:{}\ndiscordPresence:{}\n",
+            "fullbright:{}\ndynamicLights:{}\nzoom:{}\nzoomKey:{}\nzoomLevel:{}\nzoomSmooth:{}\nzoomSensitivity:{}\nfps:{}\nfpsCorner:{}\nfpsLows:{}\nkeystrokes:{}\nkeystrokesCorner:{}\nkeystrokesCps:{}\nmovedToMods:{}\nminimap:{}\nminimapCorner:{}\nminimapSize:{}\nminimapShape:{}\nminimapZoom:{}\nminimapRotate:{}\nautoReconnect:{}\nownNameTag:{}\nmouseTweaks:{}\nmouseTweaksWheel:{}\nsort:{}\nsortKey:{}\n{}:{}\nagentControl:{}\ndiscordPresence:{}\n",
             bool_text(self.fullbright),
             bool_text(self.dynamic_lights),
             bool_text(self.zoom),
@@ -251,6 +254,7 @@ impl Extras {
             self.minimap_zoom,
             bool_text(self.minimap_rotate),
             bool_text(self.auto_reconnect),
+            bool_text(self.own_name_tag),
             bool_text(self.mouse_tweaks),
             bool_text(self.mouse_tweaks_wheel),
             bool_text(self.sort),
@@ -282,7 +286,7 @@ impl Extras {
 }
 
 /// The field-of-view modifier target `Camera.tickFov` eases toward: vanilla's
-/// (`getFieldOfViewModifier`) divided by a mod's zoom (`render.set-zoom`). A
+/// (`getFieldOfViewModifier`) divided by a mod's zoom (`native_zoom`). A
 /// zoom of 1 leaves it as is.
 pub fn fov_target(vanilla: f32, zoom: f32) -> f32 {
     if zoom == 1.0 { vanilla } else { vanilla / zoom }
@@ -378,6 +382,7 @@ impl Cps {
 pub enum Item {
     Fullbright,
     DynamicLights,
+    OwnNameTag,
     AutoReconnect,
     MouseTweaks,
     MouseTweaksWheel,
@@ -396,6 +401,8 @@ pub fn rows() -> Vec<Result<Item, &'static str>> {
         Err("Lighting"),
         Ok(Fullbright),
         Ok(DynamicLights),
+        Err("Third person"),
+        Ok(OwnNameTag),
         Err("Inventory"),
         Ok(MouseTweaks),
         Ok(MouseTweaksWheel),
@@ -410,6 +417,7 @@ impl Item {
         match self {
             Item::Fullbright => "Fullbright",
             Item::DynamicLights => "Dynamic lights",
+            Item::OwnNameTag => "Own name tag",
             Item::AutoReconnect => "Auto-reconnect",
             Item::MouseTweaks => "Mouse Tweaks controls",
             Item::MouseTweaksWheel => "Scroll wheel moves items",
@@ -426,7 +434,7 @@ impl Item {
         Some(match self {
             MouseTweaksWheel => MouseTweaks,
             SortKey => Sort,
-            Fullbright | DynamicLights | MouseTweaks | Sort | AutoReconnect | NoAi
+            Fullbright | DynamicLights | OwnNameTag | MouseTweaks | Sort | AutoReconnect | NoAi
             | AgentControl | DiscordPresence => {
                 return None;
             }
@@ -439,6 +447,9 @@ impl Item {
             Item::DynamicLights => {
                 "Torches and other light sources held, dropped or on fire light the blocks around them."
             }
+            Item::OwnNameTag => {
+                "Shows your name above your head in third person, as other players see it. Hidden when the server hides your team's names or you're invisible."
+            }
             Item::AutoReconnect => {
                 "Rejoins a server after a lost connection or a restart, never after a kick or ban."
             }
@@ -471,7 +482,9 @@ impl Item {
         match self {
             Item::Fullbright => Some(Cost::None),
             Item::DynamicLights => Some(Cost::Low),
-            Item::AutoReconnect | Item::MouseTweaks | Item::Sort => Some(Cost::None),
+            Item::OwnNameTag | Item::AutoReconnect | Item::MouseTweaks | Item::Sort => {
+                Some(Cost::None)
+            }
             _ => None,
         }
     }
@@ -480,6 +493,7 @@ impl Item {
         Some(match self {
             Item::Fullbright => e.fullbright,
             Item::DynamicLights => e.dynamic_lights,
+            Item::OwnNameTag => e.own_name_tag,
             Item::AutoReconnect => e.auto_reconnect,
             Item::MouseTweaks => e.mouse_tweaks,
             Item::MouseTweaksWheel => e.mouse_tweaks_wheel,
@@ -506,6 +520,7 @@ impl Item {
         match self {
             Item::Fullbright => e.fullbright = !e.fullbright,
             Item::DynamicLights => e.dynamic_lights = !e.dynamic_lights,
+            Item::OwnNameTag => e.own_name_tag = !e.own_name_tag,
             Item::AutoReconnect => e.auto_reconnect = !e.auto_reconnect,
             Item::MouseTweaks => e.mouse_tweaks = !e.mouse_tweaks,
             Item::MouseTweaksWheel => e.mouse_tweaks_wheel = !e.mouse_tweaks_wheel,
@@ -534,7 +549,7 @@ mod tests {
         let d = Extras::default();
         assert!(!d.fullbright && !d.dynamic_lights);
         assert!(!d.zoom && !d.fps && !d.keystrokes && !d.minimap && !d.auto_reconnect);
-        assert!(!d.mouse_tweaks && !d.sort);
+        assert!(!d.mouse_tweaks && !d.sort && !d.own_name_tag);
         assert!(d.discord_presence);
         assert_eq!(Extras::parse(""), d);
         assert_eq!(Extras::parse(&d.serialize()), d);
@@ -558,6 +573,8 @@ mod tests {
         e.minimap_rotate = true;
         e.minimap_corner = Corner::BottomLeft;
         e.auto_reconnect = true;
+        Item::OwnNameTag.cycle(&mut e, false);
+        assert_eq!(Item::OwnNameTag.switch(&e), Some(true));
         e.mouse_tweaks = true;
         e.mouse_tweaks_wheel = false;
         e.sort = true;

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

@@ -70,6 +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;
@@ -93,6 +94,7 @@ pub mod pack_uniforms;
 mod pack_weather;
 mod page_runs;
 pub mod panorama;
+mod readback;
 mod resident;
 mod stars;
 mod sunrise_fan;
@@ -355,6 +357,14 @@ struct BorderUniform {
     color: [f32; 4],
     offset: [f32; 4],
 }
+/// A frame to save as a PNG: F2's screenshot, an agent's `game_screenshot`,
+/// or the icon the Select World list shows.
+pub struct ScreenshotRequest {
+    pub path: PathBuf,
+    /// `GameRenderer.takeAutoScreenshot`: centre-crop the frame to a square
+    /// and average it down to this size. `None` saves the frame as drawn.
+    pub size: Option<[u32; 2]>,
+}
 pub struct Renderer {
     instance: wgpu::Instance,
     adapter: wgpu::Adapter,
@@ -382,6 +392,11 @@ pub struct Renderer {
     pub last_wait: std::time::Duration,
     /// CPU time of the last `render`, waits excluded.
     pub last_encode: std::time::Duration,
+    /// What the system says about the window's display, watched only while HDR output
+    /// is on; before `window`, so it's dropped first.
+    display: DisplayWatch,
+    /// The watch was just made: the settings' Auto values take what it reported.
+    display_fresh: bool,
     window: Arc<Window>,
     pub device: wgpu::Device,
     pub queue: wgpu::Queue,
@@ -568,6 +583,8 @@ 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,
@@ -577,8 +594,8 @@ pub struct Renderer {
     pub section_draw_calls: usize,
     pub uploaded_bytes: u64,
     started: Instant,
-    /// Write the next presented frame to this PNG path (control socket).
-    pub screenshot: Option<PathBuf>,
+    /// The next frame to write to a PNG path (control socket, F2, world icon).
+    pub screenshot: Option<ScreenshotRequest>,
     /// Outcome of the last screenshot: frame size, or the error.
     pub screenshot_result: Option<std::result::Result<[u32; 2], String>>,
     /// Brightness option (lightmap gamma), 0..1.
@@ -1170,6 +1187,7 @@ impl Renderer {
             }
             surface.configure(&device, &config);
             let hdr_output = hdr::output(&caps);
+            crate::graphics::offer_hdr(hdr_output.is_some());
             if previous.is_none() {
                 log::info!(
                     "Horizon renderer: HDR output {}",
@@ -2582,6 +2600,8 @@ impl Renderer {
             ));
         }
         Ok(Self {
+            display: DisplayWatch::default(),
+            display_fresh: false,
             instance,
             adapter,
             surface,
@@ -2724,6 +2744,7 @@ impl Renderer {
             pack_terrain_flat: false,
             hud,
             menu_blur: None,
+            readback: readback::Readback::default(),
             info,
             suspended: !drawable_size(size.width, size.height, max_side),
             drawn_sections: 0,
@@ -3243,7 +3264,7 @@ 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) {
@@ -3258,7 +3279,7 @@ 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
@@ -3288,7 +3309,15 @@ 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,
+        ui: 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
@@ -3299,6 +3328,16 @@ impl Renderer {
             } else if let Some(marker) = self.hdr_marker.take() {
                 let _ = std::fs::remove_file(marker);
             }
+            // Only HDR output asks the system about the display, so with HDR off the
+            // game never waits on the compositor for it.
+            self.display = if output.is_some() {
+                let (watch, now) = DisplayWatch::new(&self.window);
+                crate::graphics::report(now);
+                self.display_fresh = true;
+                watch
+            } else {
+                DisplayWatch::default()
+            };
             let format = self.config.format.remove_srgb_suffix();
             self.hdr = output.map(|output| hdr::Hdr::new(&self.device, format, output));
             self.configure_surface();
@@ -3311,16 +3350,35 @@ impl Renderer {
                 None => log::info!("Horizon renderer: HDR off"),
             }
         }
+        if let Some(hdr) = &mut self.hdr {
+            hdr.ui = ui;
+        }
         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();
         }
     }
+    /// Whether what the system reports for the display changed (another output, the
+    /// player recalibrating the desktop): the settings' Auto values follow it then, so
+    /// apply them again.
+    pub fn display_changed(&mut self) -> bool {
+        flush_display_log();
+        if std::mem::take(&mut self.display_fresh) {
+            return true;
+        }
+        let Some(now) = self.display.changed() else {
+            return false;
+        };
+        crate::graphics::report(now);
+        true
+    }
     /// `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;
@@ -3678,7 +3736,12 @@ 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
@@ -5200,6 +5263,10 @@ impl Renderer {
                 ((world_quads + additive_quads) * 4) as i32,
                 0..1,
             );
+            drop(pass);
+            if let Some(hdr) = &self.hdr {
+                hdr.mark_hand(&mut encoder);
+            }
         }
         // GameRenderer.render: LevelRenderer.blitEntityOutline after the level and the hand.
         self.entity_outline.draw(
@@ -5208,6 +5275,13 @@ impl Renderer {
             &self.entity_group,
             &self.indices,
         );
+        // The world icon grabs here: after the level and the hand, before
+        // the effects and the HUD draw over them (`tryTakeScreenshotIfNeeded`
+        // runs right after `renderLevel`).
+        let readback = self
+            .screenshot
+            .take_if(|request| request.size.is_some())
+            .and_then(|request| self.take_readback(request, &mut encoder, &target_texture));
         if !frame.screen.is_empty() {
             let attachments = [Some(wgpu::RenderPassColorAttachment {
                 view: &view_target,
@@ -5311,24 +5385,20 @@ impl Renderer {
                 (&view_target, self.config.format.remove_srgb_suffix()),
             );
         }
-        let readback = self.screenshot.take().and_then(|path| {
-            // 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)))
-            } else {
-                self.screenshot_result = Some(Err(format!(
-                    "screenshots need a 32-bit surface format, not {:?}",
-                    self.config.format
-                )));
-                None
-            }
+        let readback = readback.or_else(|| {
+            self.screenshot
+                .take()
+                .and_then(|request| self.take_readback(request, &mut encoder, &target_texture))
         });
         self.uploads.finish(&encoder);
         if has_section_copies {
             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);
         }
@@ -5349,9 +5419,9 @@ impl Renderer {
         if let Some(Some(timer)) = Self::pass_timer(&mut self.pack_post, &mut self.native) {
             timer.submitted(&self.queue);
         }
-        if let Some((path, buffer)) = readback {
+        if let Some((request, buffer)) = readback {
             self.screenshot_result = Some(
-                self.write_screenshot(&path, &buffer)
+                self.write_screenshot(&request, &buffer)
                     .map_err(|e| e.to_string()),
             );
         }
@@ -5401,43 +5471,68 @@ 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,
+    /// Take a screenshot request: queue the frame's copy, or report why the
+    /// frame cannot be read back.
+    fn take_readback(
+        &mut self,
+        request: ScreenshotRequest,
         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());
+    ) -> Option<(ScreenshotRequest, wgpu::Buffer)> {
+        // 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) {
+            let size = [self.config.width, self.config.height];
+            Some((request, copy_frame(&self.device, encoder, texture, size)))
+        } else {
+            self.screenshot_result = Some(Err(format!(
+                "screenshots need a 32-bit surface format, not {:?}",
+                self.config.format
+            )));
+            None
         }
+    }
+    fn write_screenshot(
+        &self,
+        request: &ScreenshotRequest,
+        buffer: &wgpu::Buffer,
+    ) -> Result<[u32; 2]> {
         let (sender, receiver) = std::sync::mpsc::channel();
         buffer.map_async(wgpu::MapMode::Read, .., move |r| {
             let _ = sender.send(r);
@@ -5452,7 +5547,7 @@ 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(),
@@ -5472,8 +5567,18 @@ impl Renderer {
             }
         }
         buffer.unmap();
+        // NativeImage.resizeSubRectTo on takeAutoScreenshot's grab: the icon
+        // is the frame's centre square averaged down to its size.
+        let (width, height, pixels) = match request.size {
+            Some(size) => (
+                size[0],
+                size[1],
+                square_downscale(&pixels, self.config.width, self.config.height, size),
+            ),
+            None => (self.config.width, self.config.height, pixels),
+        };
         let mut encoder = png::Encoder::new(
-            std::io::BufWriter::new(std::fs::File::create(path)?),
+            std::io::BufWriter::new(std::fs::File::create(&request.path)?),
             width,
             height,
         );
@@ -5483,6 +5588,42 @@ impl Renderer {
         Ok([width, height])
     }
 }
+/// Centre-crop the frame to a square and average it down to `size`.
+pub(crate) fn square_downscale(pixels: &[u8], width: u32, height: u32, size: [u32; 2]) -> Vec<u8> {
+    let (side, cx, cy) = if width > height {
+        (height, (width - height) / 2, 0)
+    } else {
+        (width, 0, (height - width) / 2)
+    };
+    let [tw, th] = size;
+    let mut out = vec![0u8; (tw * th * 4) as usize];
+    for ty in 0..th {
+        let y0 = cy + ty * side / th;
+        let y1 = cy + (ty + 1) * side / th;
+        for tx in 0..tw {
+            let x0 = cx + tx * side / tw;
+            let x1 = cx + (tx + 1) * side / tw;
+            let (mut r, mut g, mut b) = (0u32, 0u32, 0u32);
+            for y in y0..y1 {
+                for x in x0..x1 {
+                    let p = ((y * width + x) * 4) as usize;
+                    r += u32::from(pixels[p]);
+                    g += u32::from(pixels[p + 1]);
+                    b += u32::from(pixels[p + 2]);
+                }
+            }
+            let count = (x1 - x0) * (y1 - y0);
+            let o = ((ty * tw + tx) * 4) as usize;
+            out[o..o + 4].copy_from_slice(&[
+                (r / count) as u8,
+                (g / count) as u8,
+                (b / count) as u8,
+                255,
+            ]);
+        }
+    }
+    out
+}
 /// Camera-relative clip planes (`Frustum`).
 #[derive(Clone, Copy, Debug)]
 pub struct Frustum {
@@ -6013,3 +6154,101 @@ mod sprite_upload_tests {
         }
     }
 }
+
+/// What the system says about the window's display, kept up to date: on Wayland, the
+/// compositor's preferred image description of the surface.
+#[derive(Default)]
+struct DisplayWatch {
+    #[cfg(target_os = "linux")]
+    wayland: Option<horizon_hdr::wayland::Watch>,
+}
+impl DisplayWatch {
+    /// Starts watching, with what the system reports now.
+    fn new(window: &Window) -> (Self, Option<crate::graphics::Reported>) {
+        #[cfg(target_os = "linux")]
+        if let Some((wayland, now)) = horizon_hdr::wayland::Watch::new(window) {
+            let watch = Self {
+                wayland: Some(wayland),
+            };
+            return (watch, now.map(reported));
+        }
+        let _ = window;
+        (Self::default(), None)
+    }
+    /// What the system reports, if that changed since the last call.
+    fn changed(&mut self) -> Option<Option<crate::graphics::Reported>> {
+        #[cfg(target_os = "linux")]
+        if let Some(wayland) = &mut self.wayland {
+            return wayland.changed().map(|now| now.map(reported));
+        }
+        None
+    }
+}
+
+/// The log of what the system reports about the display: one line per change. The
+/// renderer is made anew a few times while the game starts and each asks again, and a
+/// slider dragged in the desktop's settings changes the values many times a second, so
+/// a change within [`DISPLAY_LOG_QUIET`] of the last line waits until the values have
+/// held that long, and only the one they settled on is logged.
+struct DisplayLog {
+    last: String,
+    at: Option<std::time::Instant>,
+    pending: Option<(String, std::time::Instant)>,
+}
+static DISPLAY_LOG: std::sync::Mutex<DisplayLog> = std::sync::Mutex::new(DisplayLog {
+    last: String::new(),
+    at: None,
+    pending: None,
+});
+const DISPLAY_LOG_QUIET: std::time::Duration = std::time::Duration::from_secs(1);
+fn log_display(line: String) {
+    let now = std::time::Instant::now();
+    let mut log = DISPLAY_LOG
+        .lock()
+        .unwrap_or_else(std::sync::PoisonError::into_inner);
+    if line == log.last {
+        log.pending = None;
+    } else if log.at.is_none_or(|at| now - at >= DISPLAY_LOG_QUIET) {
+        log::info!("{line}");
+        (log.last, log.at, log.pending) = (line, Some(now), None);
+    } else {
+        log.pending = Some((line, now));
+    }
+}
+/// Logs a change [`log_display`] held back, once the values have held for
+/// [`DISPLAY_LOG_QUIET`].
+fn flush_display_log() {
+    let now = std::time::Instant::now();
+    let mut log = DISPLAY_LOG
+        .lock()
+        .unwrap_or_else(std::sync::PoisonError::into_inner);
+    if let Some((_, since)) = &log.pending
+        && now - *since >= DISPLAY_LOG_QUIET
+        && let Some((line, _)) = log.pending.take()
+    {
+        log::info!("{line}");
+        (log.last, log.at) = (line, Some(now));
+    }
+}
+
+/// What a compositor's luminances mean in HDR output's scale.
+///
+/// KWin maps content's reference white (203 nits in PQ, BT.2408) onto its own, so the
+/// desktop's white is 203 there and the peak is the target's maximum over that ratio.
+/// Checked on KWin. Hyprland (0.57) reports the standard 203, and shows HDR windows below
+/// the SDR white of its desktop (which it doesn't report), so Auto can't match its desktop
+/// there. Other compositors are unchecked. The peak is kept within the settings' lowest and
+/// PQ's top, so the metadata never ends below the black level.
+#[cfg(target_os = "linux")]
+fn reported(l: horizon_hdr::wayland::Luminances) -> crate::graphics::Reported {
+    let peak = (l.target_max * 203.0 / l.reference.max(1.0)).round() as u32;
+    log_display(format!(
+        "Horizon renderer: the compositor shows this window with reference white {} nits, \
+         {}..{} nits: peak {peak} nits in HDR output's scale",
+        l.reference, l.target_min, l.target_max,
+    ));
+    crate::graphics::Reported {
+        paper_white: 203,
+        peak: peak.clamp(200, 10_000),
+    }
+}

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

@@ -63,6 +63,12 @@ struct Targets {
 pub struct Hdr {
     layout: wgpu::BindGroupLayout,
     pipeline: wgpu::RenderPipeline,
+    /// Zeroes the frame's alpha once the world is kept (`keep_world`): what draws after,
+    /// the hand, HUD and menus, raises it, so HDR output knows where they cover the world.
+    clear_alpha: wgpu::RenderPipeline,
+    /// Scales the frame's alpha down to 1/255 where the hand drew (`mark_hand`), so HDR
+    /// output keeps the hand at the world's brightness.
+    hand_mark: wgpu::RenderPipeline,
     params: wgpu::Buffer,
     pub output: Output,
     /// The frame's format: what every other pipeline draws in.
@@ -73,6 +79,10 @@ 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,
+    /// The HUD and menus' brightness, as a share of paper white (0.25..=1).
+    pub ui: f32,
 }
 
 impl Hdr {
@@ -138,6 +148,48 @@ impl Hdr {
             multiview_mask: None,
             cache: None,
         });
+        let alpha_pass = |label, blend| {
+            device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+                label: Some(label),
+                layout: Some(&device.create_pipeline_layout(&Default::default())),
+                vertex: wgpu::VertexState {
+                    module: &shader,
+                    entry_point: Some("vs_hdr"),
+                    compilation_options: Default::default(),
+                    buffers: &[],
+                },
+                primitive: Default::default(),
+                depth_stencil: None,
+                multisample: Default::default(),
+                fragment: Some(wgpu::FragmentState {
+                    module: &shader,
+                    entry_point: Some("fs_clear_alpha"),
+                    compilation_options: Default::default(),
+                    targets: &[Some(wgpu::ColorTargetState {
+                        format,
+                        blend,
+                        write_mask: wgpu::ColorWrites::ALPHA,
+                    })],
+                }),
+                multiview_mask: None,
+                cache: None,
+            })
+        };
+        let clear_alpha = alpha_pass("Horizon HDR UI mask", None);
+        // Alpha times the blend constant (1/255): the hand's 1 becomes 1/255, the world's 0
+        // stays 0.
+        let scale_alpha = wgpu::BlendComponent {
+            src_factor: wgpu::BlendFactor::Zero,
+            dst_factor: wgpu::BlendFactor::Constant,
+            operation: wgpu::BlendOperation::Add,
+        };
+        let hand_mark = alpha_pass(
+            "Horizon HDR hand mark",
+            Some(wgpu::BlendState {
+                color: scale_alpha,
+                alpha: scale_alpha,
+            }),
+        );
         let params = device.create_buffer(&wgpu::BufferDescriptor {
             label: Some("Horizon HDR parameters"),
             size: 32,
@@ -147,6 +199,8 @@ impl Hdr {
         Self {
             layout,
             pipeline,
+            clear_alpha,
+            hand_mark,
             params,
             output,
             format,
@@ -154,6 +208,8 @@ 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,
+            ui: 1.0,
         }
     }
 
@@ -210,7 +266,9 @@ impl Hdr {
         self.targets.as_ref().unwrap().frame.clone()
     }
 
-    /// Keeps the world as drawn so far, before the hand and HUD cover it.
+    /// Keeps the world as drawn so far, before the hand and HUD cover it, then zeroes the
+    /// frame's alpha: the world's marks live on in the copy, and whatever draws from here
+    /// on raises the alpha where it covers the world.
     pub fn keep_world(&self, encoder: &mut wgpu::CommandEncoder) {
         let Some(t) = &self.targets else {
             return;
@@ -220,6 +278,56 @@ impl Hdr {
             t.world.as_image_copy(),
             t.frame.size(),
         );
+        let view = t.frame.create_view(&Default::default());
+        let attachments = [Some(wgpu::RenderPassColorAttachment {
+            view: &view,
+            resolve_target: None,
+            depth_slice: None,
+            ops: wgpu::Operations {
+                load: wgpu::LoadOp::Load,
+                store: wgpu::StoreOp::Store,
+            },
+        })];
+        let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("Horizon HDR UI mask"),
+            color_attachments: &attachments,
+            ..Default::default()
+        });
+        pass.set_pipeline(&self.clear_alpha);
+        pass.draw(0..3, 0..1);
+    }
+
+    /// After the hand: its pixels' alpha goes down to 1/255, below anything the HUD and
+    /// menus leave, so HDR output tells the hand (the world's brightness, never lifted)
+    /// from the UI (UI Brightness).
+    pub fn mark_hand(&self, encoder: &mut wgpu::CommandEncoder) {
+        let Some(t) = &self.targets else {
+            return;
+        };
+        let view = t.frame.create_view(&Default::default());
+        let attachments = [Some(wgpu::RenderPassColorAttachment {
+            view: &view,
+            resolve_target: None,
+            depth_slice: None,
+            ops: wgpu::Operations {
+                load: wgpu::LoadOp::Load,
+                store: wgpu::StoreOp::Store,
+            },
+        })];
+        let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("Horizon HDR hand mark"),
+            color_attachments: &attachments,
+            ..Default::default()
+        });
+        pass.set_pipeline(&self.hand_mark);
+        let a = 1.0 / 255.0;
+        pass.set_blend_constant(wgpu::Color {
+            r: a,
+            g: a,
+            b: a,
+            a,
+        });
+        pass.draw(0..3, 0..1);
     }
 
     /// Writes the finished frame to the swapchain image `target`.
@@ -240,8 +348,8 @@ impl Hdr {
             f32::from(u8::from(world)),
             f32::from(u8::from(self.debug)),
             f32::from(u8::from(self.output == Output::Pq)),
-            0.0,
-            0.0,
+            self.black.clamp(0.0, paper),
+            self.ui.clamp(0.25, 1.0),
             0.0,
         ];
         queue.write_buffer(&self.params, 0, bytemuck::cast_slice(&params));

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/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

@@ -2,13 +2,39 @@
 //! `horizon-graphics.txt` next to `options.txt` so that file stays exactly
 //! vanilla's. Every default reproduces vanilla's rendering; only choices the
 //! player makes here depart from it.
-use std::{fs, path::Path};
+use std::{
+    fs,
+    path::Path,
+    sync::atomic::{AtomicU32, Ordering},
+};
 
 pub const FILE: &str = "horizon-graphics.txt";
 /// Written beside it before HDR output is switched on and removed once the first HDR frame is
 /// presented. Found at the next start, it means HDR output took the game down, so HDR starts off.
 pub const HDR_MARKER: &str = "horizon-hdr-pending";
 
+/// What the system reports for the display HDR output goes to, in nits in HDR output's
+/// scale: where its SDR white sits (the desktop's white) and the peak.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct Reported {
+    pub paper_white: u32,
+    pub peak: u32,
+}
+
+static REPORTED: [AtomicU32; 2] = [AtomicU32::new(0), AtomicU32::new(0)];
+
+/// Sets what the system reports (the renderer, when it opens its surface).
+pub fn report(reported: Option<Reported>) {
+    let (paper_white, peak) = reported.map_or((0, 0), |r| (r.paper_white, r.peak));
+    REPORTED[0].store(paper_white, Ordering::Relaxed);
+    REPORTED[1].store(peak, Ordering::Relaxed);
+}
+/// What the system reports, if it does.
+pub fn reported() -> Option<Reported> {
+    let [paper_white, peak] = REPORTED.each_ref().map(|n| n.load(Ordering::Relaxed));
+    (peak > 0).then_some(Reported { paper_white, peak })
+}
+
 /// Simple-level presets. `Custom` leaves every option as the player set it.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
 pub enum Preset {
@@ -285,6 +311,16 @@ pub fn reduced_far_detail_suggested() -> bool {
     REDUCED_SUGGESTED.load(std::sync::atomic::Ordering::Relaxed)
 }
 
+static HDR_OFFERED: std::sync::atomic::AtomicBool = std::sync::atomic::AtomicBool::new(false);
+/// Whether the display path offers HDR output (HDR10 or scRGB): set when the renderer
+/// opens its surface; the settings open HDR's screen only then.
+pub fn offer_hdr(on: bool) {
+    HDR_OFFERED.store(on, std::sync::atomic::Ordering::Relaxed);
+}
+pub fn hdr_offered() -> bool {
+    HDR_OFFERED.load(std::sync::atomic::Ordering::Relaxed)
+}
+
 /// The farthest LOD Distance, in chunks, on integrated GPUs other than
 /// Apple's: they share the CPU's memory bandwidth, and past it far terrain
 /// costs them more frame time than it is worth.
@@ -343,10 +379,18 @@ pub struct Graphics {
     pub upscaling: Upscaling,
     /// HDR output (HDR10, or scRGB), where the display path offers it.
     pub hdr: bool,
-    /// HDR paper white (where SDR white sits), in nits.
+    /// HDR paper white (where SDR white sits), in nits; 0 is Auto: the desktop's SDR
+    /// white, as the system reports it ([`Graphics::paper_white_nits`]).
     pub hdr_paper_white: u32,
-    /// HDR peak brightness the world's highlights reach, in nits.
+    /// HDR peak brightness the world's highlights reach, in nits; 0 is Auto:
+    /// what the system reports for the display ([`Graphics::peak_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,
+    /// HDR brightness of the HUD and menus, in percent of paper white (25..=100); the
+    /// first-person hand stays at the world's.
+    pub hdr_ui_brightness: 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.
@@ -381,8 +425,10 @@ impl Default for Graphics {
             taa: false,
             upscaling: Upscaling::Native,
             hdr: false,
-            hdr_paper_white: 200,
-            hdr_peak: 1000,
+            hdr_paper_white: 0,
+            hdr_peak: 0,
+            hdr_black_level: 0,
+            hdr_ui_brightness: 100,
             battery: false,
             api: GraphicsApi::Auto,
             shader_pack: String::new(),
@@ -445,8 +491,22 @@ impl Graphics {
                 "taa" => g.taa = flag(g.taa),
                 "upscaling" => g.upscaling = Upscaling::parse(value),
                 "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),
+                "hdrPaperWhite" => {
+                    g.hdr_paper_white = match number(g.hdr_paper_white) {
+                        0 => 0,
+                        n => n.clamp(80, 480),
+                    }
+                }
+                "hdrPeak" => {
+                    g.hdr_peak = match number(g.hdr_peak) {
+                        0 => 0,
+                        n => n.clamp(200, 2000),
+                    }
+                }
+                "hdrBlackLevel" => g.hdr_black_level = number(g.hdr_black_level).min(100),
+                "hdrUiBrightness" => {
+                    g.hdr_ui_brightness = number(g.hdr_ui_brightness).clamp(25, 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 +524,7 @@ 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:{}\nhdrUiBrightness:{}\nbatteryMode:{}\ngraphicsApi:{}\npickedShaderPack:{}\n",
             self.preset.name(),
             self.lod_distance,
             self.far_detail.name(),
@@ -494,6 +554,8 @@ impl Graphics {
             bool_text(self.hdr),
             self.hdr_paper_white,
             self.hdr_peak,
+            self.hdr_black_level,
+            self.hdr_ui_brightness,
             bool_text(self.battery),
             self.api.name(),
             self.shader_pack,
@@ -502,6 +564,22 @@ impl Graphics {
     pub fn save(&self, dir: &Path) {
         let _ = fs::write(dir.join(FILE), self.serialize());
     }
+    /// Paper white, in nits: the player's, or on Auto the desktop's SDR white as the
+    /// system reports it, else 203 (BT.2408's reference white).
+    pub fn paper_white_nits(&self) -> u32 {
+        match self.hdr_paper_white {
+            0 => reported().map_or(203, |r| r.paper_white),
+            n => n,
+        }
+    }
+    /// The peak the world's highlights reach, in nits: the player's, or on Auto
+    /// what the system reports, else 1000.
+    pub fn peak_nits(&self) -> u32 {
+        match self.hdr_peak {
+            0 => reported().map_or(1000, |r| r.peak),
+            n => n,
+        }
+    }
     /// Worker threads for chunk generation and meshing.
     pub fn worker_threads(&self) -> usize {
         if self.workers > 0 {
@@ -611,12 +689,19 @@ mod tests {
             hdr: true,
             hdr_paper_white: 240,
             hdr_peak: 1400,
+            hdr_black_level: 12,
+            hdr_ui_brightness: 60,
             battery: true,
             api: GraphicsApi::Dx12,
             shader_pack: "Golden Hour".into(),
         };
         assert_eq!(Graphics::parse(&g.serialize()), g);
         assert_eq!(Graphics::parse(""), Graphics::default());
+        // 0 is Auto; anything else is a peak the slider reaches.
+        assert_eq!(Graphics::parse("hdrPeak:0\n").hdr_peak, 0);
+        assert_eq!(Graphics::parse("hdrPeak:50\n").hdr_peak, 200);
+        assert_eq!(Graphics::parse("hdrPaperWhite:0\n").hdr_paper_white, 0);
+        assert_eq!(Graphics::parse("hdrPaperWhite:5\n").hdr_paper_white, 80);
         // The old menus' Simple / Advanced choice is ignored, and so is the
         // shader pack older versions saved.
         assert_eq!(Graphics::parse("level:advanced\n"), Graphics::default());

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

@@ -130,8 +130,9 @@ impl Style {
         label: &Text,
         value: f32,
         hover: bool,
+        active: bool,
     ) {
-        ui::slider(batch, atlas, x, y, w, label, value, hover, true);
+        ui::slider(batch, atlas, x, y, w, label, value, hover && active, active);
     }
     /// The cost tag and the description beside a control, wrapped to two lines.
     pub fn description(

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

@@ -1,4 +1,4 @@
-//! Horizon's graphics settings screens, Simple and Advanced: which settings
+//! Horizon's graphics settings screens, Simple, Advanced and HDR: which settings
 //! they show, in what groups, with what description and cost, and their
 //! input. How they look comes from `graphics_style`.
 use crate::{
@@ -14,6 +14,8 @@ use crate::{
 pub enum Level {
     Simple,
     Advanced,
+    /// HDR output's own settings, opened from Advanced while HDR is on.
+    Hdr,
 }
 
 /// Horizon's own settings (`graphics::Graphics`).
@@ -38,8 +40,12 @@ pub enum H {
     Antialiasing,
     Upscaling,
     Hdr,
-    HdrPaperWhite,
+    /// Opens `Level::Hdr`.
+    HdrSettings,
+    HdrBlackLevel,
     HdrPeak,
+    HdrPaperWhite,
+    HdrUiBrightness,
     BatteryMode,
     GraphicsApi,
 }
@@ -120,6 +126,34 @@ pub fn rows(level: Level) -> Vec<Row> {
     );
     let mut rows = match level {
         Level::Simple => vec![preset, render, lod, far, fov, fps, vsync, gui],
+        Level::Hdr => vec![
+            Row::Header("HDR"),
+            h(
+                H::Hdr,
+                None,
+                "Lava, fire and sunlight shine brighter than white. Needs an HDR display.",
+            ),
+            h(
+                H::HdrBlackLevel,
+                None,
+                "Your display's darkest black. 0 for OLED; LCDs glow a little.",
+            ),
+            h(
+                H::HdrPeak,
+                None,
+                "How bright highlights get. Auto: the peak your system reports.",
+            ),
+            h(
+                H::HdrPaperWhite,
+                None,
+                "How bright white paper and menus look. Auto: your desktop's white.",
+            ),
+            h(
+                H::HdrUiBrightness,
+                None,
+                "How bright the HUD and menus are, against paper white.",
+            ),
+        ],
         Level::Advanced => vec![
             Row::Header("Rendering"),
             render,
@@ -230,20 +264,10 @@ pub fn rows(level: Level) -> Vec<Row> {
                 "Renders the world smaller and rebuilds it with TAA. Faster, softer.",
             ),
             h(
-                H::Hdr,
+                H::HdrSettings,
                 None,
                 "HDR output on an HDR display: lava, fire and sunlight shine brighter.",
             ),
-            h(
-                H::HdrPaperWhite,
-                None,
-                "HDR: how bright white paper and menus look. Match your desktop.",
-            ),
-            h(
-                H::HdrPeak,
-                None,
-                "HDR: how bright the brightest highlights get. Your display's peak.",
-            ),
             h(
                 H::PresentMode,
                 None,
@@ -351,8 +375,18 @@ impl H {
             }
             H::Workers => Some(g.workers as f32 / max_workers() as f32),
             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),
+            // Auto, then 80..480 by 10.
+            H::HdrPaperWhite => Some(match g.hdr_paper_white {
+                0 => 0.0,
+                n => (n as f32 - 70.0) / 410.0,
+            }),
+            // Auto, then 200..2000 by 50.
+            H::HdrPeak => Some(match g.hdr_peak {
+                0 => 0.0,
+                n => (n as f32 - 150.0) / 1850.0,
+            }),
+            H::HdrBlackLevel => Some(g.hdr_black_level as f32 / 100.0),
+            H::HdrUiBrightness => Some((g.hdr_ui_brightness as f32 - 25.0) / 75.0),
             _ => None,
         }
     }
@@ -403,8 +437,23 @@ impl H {
             ),
             H::Upscaling => labelled("Upscaling", g.upscaling.label()),
             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::HdrSettings => Text::literal("HDR Settings..."),
+            H::HdrPaperWhite => match g.hdr_paper_white {
+                0 => labelled(
+                    "Paper White",
+                    format!("Auto ({} nits)", g.paper_white_nits()),
+                ),
+                n => labelled("Paper White", format!("{n} nits")),
+            },
+            H::HdrPeak => match g.hdr_peak {
+                0 => labelled("Peak Brightness", format!("Auto ({} nits)", g.peak_nits())),
+                n => labelled("Peak Brightness", format!("{n} nits")),
+            },
+            H::HdrBlackLevel => labelled(
+                "Black Level",
+                format!("{:.2} nits", g.hdr_black_level as f32 / 100.0),
+            ),
+            H::HdrUiBrightness => labelled("UI Brightness", format!("{}%", g.hdr_ui_brightness)),
             H::BatteryMode => labelled("Battery Mode", on_off(g.battery)),
             H::GraphicsApi => labelled("Graphics API", g.api.label()),
             H::Overlay => labelled(
@@ -427,8 +476,20 @@ impl H {
             }
             H::Workers => g.workers = (v * max_workers() as f32).round() as u32,
             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::HdrPaperWhite => {
+                g.hdr_paper_white = match (v * 41.0).round() as u32 {
+                    0 => 0,
+                    step => 70 + step * 10,
+                }
+            }
+            H::HdrPeak => {
+                g.hdr_peak = match (v * 37.0).round() as u32 {
+                    0 => 0,
+                    step => 150 + step * 50,
+                }
+            }
+            H::HdrBlackLevel => g.hdr_black_level = (v * 100.0).round() as u32,
+            H::HdrUiBrightness => g.hdr_ui_brightness = (25.0 + (v * 15.0).round() * 5.0) as u32,
             _ => {}
         }
     }
@@ -504,6 +565,25 @@ impl Item {
     fn available(self) -> bool {
         !matches!(self, Item::Vanilla(o) if !o.available())
     }
+    /// Why a control can't be used now, when it can't: HDR's screen opens only where
+    /// the display offers HDR output, whatever `horizon-graphics.txt` says (a copied game
+    /// folder, a display swapped for an SDR one: the renderer leaves HDR off there, and
+    /// the saved values wait for an HDR display), and its sliders do something only
+    /// while it is on.
+    fn blocked(self, s: &Settings) -> Option<&'static str> {
+        if !self.available() {
+            return Some("This feature is not yet available in Horizon.");
+        }
+        match self {
+            Item::Horizon(H::HdrSettings | H::Hdr) if !crate::graphics::hdr_offered() => {
+                Some("Your display or system doesn't offer HDR output.")
+            }
+            Item::Horizon(
+                H::HdrBlackLevel | H::HdrPeak | H::HdrPaperWhite | H::HdrUiBrightness,
+            ) if !s.horizon.hdr => Some("Turn HDR on to use it."),
+            _ => None,
+        }
+    }
     /// On/off settings and their value.
     pub fn switch(self, s: &Settings) -> Option<bool> {
         let g = &s.horizon;
@@ -605,6 +685,7 @@ pub enum Action {
     SliderDrag,
     OpenAdvanced,
     OpenSimple,
+    OpenHdr,
     Done,
 }
 
@@ -624,15 +705,20 @@ 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 +743,7 @@ 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) {
@@ -683,6 +769,17 @@ impl GraphicsUi {
         let other = match level {
             Level::Simple => Action::OpenAdvanced,
             Level::Advanced => Action::OpenSimple,
+            // One Done, back to Advanced.
+            Level::Hdr => {
+                widgets.push(Widget {
+                    x: cx - 100.0,
+                    y: by,
+                    w: 200.0,
+                    target: Target::Button(Action::Done),
+                    list: false,
+                });
+                return (widgets, headers, content);
+            }
         };
         widgets.push(Widget {
             x: cx - 155.0,
@@ -702,7 +799,7 @@ 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,
@@ -744,12 +841,10 @@ impl GraphicsUi {
                         continue;
                     }
                     let label = item.label(s);
-                    let live = item.available();
-                    if hover && !live {
-                        tooltip = Some(atlas.font.split(
-                            &Text::literal("This feature is not yet available in Horizon."),
-                            170.0,
-                        ));
+                    let blocked = item.blocked(s);
+                    let live = blocked.is_none();
+                    if hover && let Some(why) = blocked {
+                        tooltip = Some(atlas.font.split(&Text::literal(why), 170.0));
                     }
                     match item.slider(s) {
                         Some(value) => STYLE.slider(
@@ -759,6 +854,7 @@ impl GraphicsUi {
                             &label,
                             value,
                             hover || self.dragging == Some(item),
+                            live,
                         ),
                         None => STYLE.button(
                             batch,
@@ -799,15 +895,16 @@ 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",
             Level::Advanced => "Graphics: Advanced",
+            Level::Hdr => "Graphics: HDR",
         };
         STYLE.title(batch, atlas, &Text::literal(title));
         if let Some(lines) = tooltip {
@@ -825,9 +922,14 @@ 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 +943,13 @@ 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;
@@ -851,7 +960,10 @@ impl GraphicsUi {
             return match wd.target {
                 Target::Button(action) => vec![Action::ButtonClick, action],
                 // A disabled control does nothing: no sound, no preset change.
-                Target::Item(item) if !item.available() => Vec::new(),
+                Target::Item(item) if item.blocked(s).is_some() => Vec::new(),
+                Target::Item(Item::Horizon(H::HdrSettings)) => {
+                    vec![Action::ButtonClick, Action::OpenHdr]
+                }
                 Target::Item(item) => {
                     if item.slider(s).is_some() {
                         self.dragging = Some(item);
@@ -866,14 +978,16 @@ 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);
     }
 }
 
@@ -881,6 +995,53 @@ impl GraphicsUi {
 mod tests {
     use super::*;
 
+    #[test]
+    fn hdr_settings_open_where_hdr_is_offered() {
+        let mut s = Settings::default();
+        let mut ui = GraphicsUi::default();
+        let size = (480.0, 2000.0);
+        let at = |ui: &mut GraphicsUi, s: &Settings, level, item| {
+            let (widgets, _, _) = ui.layout(level, s, size.0, size.1);
+            let w = widgets
+                .iter()
+                .find(|w| matches!(w.target, Target::Item(i) if i == item))
+                .unwrap();
+            (w.x + 1.0, w.y + 1.0)
+        };
+        let button = at(&mut ui, &s, Level::Advanced, Item::Horizon(H::HdrSettings));
+        let click = |ui: &mut GraphicsUi, s: &mut Settings, level, point| {
+            ui.click(level, s, point, size, [480, 2000], false, false)
+        };
+        crate::graphics::offer_hdr(false);
+        assert!(click(&mut ui, &mut s, Level::Advanced, button).is_empty());
+        // Not even with HDR saved on, from another computer.
+        s.horizon.hdr = true;
+        assert!(click(&mut ui, &mut s, Level::Advanced, button).is_empty());
+        s.horizon.hdr = false;
+        crate::graphics::offer_hdr(true);
+        assert_eq!(
+            click(&mut ui, &mut s, Level::Advanced, button),
+            [Action::ButtonClick, Action::OpenHdr]
+        );
+        // On HDR's screen, the sliders wait for the switch above them.
+        let peak = at(&mut ui, &s, Level::Hdr, Item::Horizon(H::HdrPeak));
+        assert!(click(&mut ui, &mut s, Level::Hdr, peak).is_empty());
+        s.horizon.hdr = true;
+        assert_eq!(
+            click(&mut ui, &mut s, Level::Hdr, peak),
+            [Action::SliderDrag]
+        );
+        let on = |level, item| {
+            extra_rows(level, &s)
+                .iter()
+                .any(|r| matches!(r, Row::Setting(x) if x.item == Item::Horizon(item)))
+        };
+        assert!(on(Level::Hdr, H::Hdr) && !on(Level::Advanced, H::Hdr));
+        assert!(on(Level::Hdr, H::HdrPeak) && !on(Level::Advanced, H::HdrPeak));
+        for item in [H::HdrBlackLevel, H::HdrPaperWhite, H::HdrUiBrightness] {
+            assert!(on(Level::Hdr, item) && !on(Level::Advanced, item));
+        }
+    }
     #[test]
     fn graphics_buttons_sound_on_press_and_sliders_on_release() {
         let mut s = Settings::default();
@@ -960,29 +1121,68 @@ 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 +1192,7 @@ 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 +16,10 @@ 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,
+    // The HUD and menus' brightness as a share of paper white.
+    ui: f32,
 };
 @group(0) @binding(2) var<uniform> params: Params;
 
@@ -56,20 +60,51 @@ 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);
 }
 
+// Hdr::keep_world: once the world is kept, the frame's alpha starts at 0 again.
+@fragment fn fs_clear_alpha() -> @location(0) vec4<f32> {
+    return vec4(0.0);
+}
+
 @fragment fn fs_hdr(@builtin(position) pos: vec4<f32>) -> @location(0) vec4<f32> {
     let at = vec2<i32>(pos.xy);
-    let c = textureLoad(frame, at, 0).rgb;
+    let f = textureLoad(frame, at, 0);
+    let c = f.rgb;
+    // What covers the world here (Hdr::keep_world): nothing at 0, the hand at
+    // 1/255 (Hdr::mark_hand: drawn at the world's brightness), else the HUD or a
+    // menu, by how much.
+    let covered = f.a > 0.0;
+    let ui = select(f.a, 0.0, f.a < 1.5 / 255.0);
     // Gamma 2.2, as SDR displays and the compositors' SDR paths decode it.
     var light = pow(max(c, vec3(0.0)), vec3(2.2));
     let w = textureLoad(world, at, 0);
     // The world's alpha is 0 on light-emitting blocks, the sun and the moon
-    // (terrain.wgsl, the celestial pipeline): only those shine.
-    if params.world > 0.5 && params.peak > 1.0 && w.a < 0.75 && shows_world(c, w.rgb) {
+    // (terrain.wgsl, the celestial pipeline): only those shine, and only where
+    // nothing was drawn over them since: grey text over the white sun still looks
+    // like the sun darkened, but it raised the frame's alpha.
+    if params.world > 0.5 && params.peak > 1.0 && w.a < 0.75 && !covered
+        && shows_world(c, w.rgb) {
         // Brightness of the world pixel, before the vignette darkens the frame
         // toward its edges: a light source shines the same anywhere on screen.
         let wl = pow(max(w.rgb, vec3(0.0)), vec3(2.2));
@@ -84,9 +119,15 @@ fn pq(nits: vec3<f32>) -> vec3<f32> {
             }
         }
     }
+    // The HUD and menus at their own brightness, by how much they cover.
+    light *= mix(1.0, params.ui, ui);
     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/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

@@ -435,6 +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]>>;
@@ -573,8 +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)>>,
@@ -777,6 +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(),
@@ -1038,7 +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);
@@ -1160,31 +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.
@@ -1198,12 +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 {
@@ -1620,6 +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);

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

@@ -36,11 +36,8 @@ pub struct Installed {
     pub description: String,
     /// Why it is not running, when it failed.
     pub problem: Option<String>,
-    /// Loaded with `--dev-mod`: always on, reloaded when rebuilt.
+    /// Loaded with `--dev-mod`: always on.
     pub dev: bool,
-    /// The running mod set a page of widgets (capability `ui`): its row
-    /// gains a Settings button.
-    pub has_settings: bool,
     /// A native mod (`game/native_hooks.rs`): built into the game, on until
     /// the player turns it off, and its settings page.
     pub native: Option<NativePage>,
@@ -178,7 +175,6 @@ mod tests {
             description: String::new(),
             problem: None,
             dev,
-            has_settings: false,
             native: None,
         };
         let mut list = ModList {

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

@@ -87,6 +87,9 @@ const MODEL_PARTS: [&str; 7] = [
 ];
 const GRAPHICS_BACKEND: &[&str] = &["default", "opengl", "vulkan"];
 const GRAPHICS_PRESET: &[&str] = &["fast", "fancy", "fabulous", "custom"];
+/// Horizon's render distance cap (vanilla stops at 32): the server protocol's
+/// view distance tops out at 127 anyway.
+pub const MAX_RENDER_DISTANCE: i32 = 128;
 const INACTIVITY: &[&str] = &["minimized", "afk"];
 const CLOUDS: &[&str] = &["false", "fast", "true"];
 const MAIN_HAND: &[&str] = &["left", "right"];
@@ -159,7 +162,7 @@ static TABLE: LazyLock<Vec<Def>> = LazyLock::new(|| {
         b("reducedDebugInfo", false),
         def("renderClouds", O(Clouds), V::Int(2)),
         i("cloudRange", 2, 128, 128),
-        i("renderDistance", 2, 64, 12),
+        i("renderDistance", 2, MAX_RENDER_DISTANCE, 12),
         i("simulationDistance", 5, 32, 12),
         u("screenEffectScale", 1.0),
         def("soundDevice", O(AnyStr), V::Str(String::new())),

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 +170,10 @@ impl Opt {
             Opt::RotateWithMinecarts => "rotateWithMinecart",
             Opt::HighContrastBlockOutlines => "highContrastBlockOutline",
             Opt::MusicFrequency => "musicFrequency",
+            Opt::SoundDevice => "soundDevice",
+            Opt::OperatorItemsTab => "operatorItemsTab",
+            Opt::QuitShortcuts => "quitShortcuts",
+            Opt::CtrlClickEmulatesRightClick => "ctrlClickEmulatesRightClick",
             Opt::ModelPart(i) => MODEL_PART_KEYS[i],
             Opt::AllowServerListing => "allowServerListing",
             Opt::RealmsNotifications => "realmsNotifications",
@@ -167,6 +197,7 @@ impl Opt {
             Opt::DiscreteScroll => "options.discrete_mouse_scroll",
             Opt::AllowCursorChanges => "options.allowCursorChanges",
             Opt::Volume(_) => "soundCategory.master",
+            Opt::SoundDevice => "options.audioDevice",
             Opt::GuiScale => "options.guiScale",
             Opt::ViewBobbing => "options.viewBobbing",
             Opt::Gamma => "options.gamma",
@@ -194,7 +225,13 @@ 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",
@@ -278,7 +315,11 @@ impl Opt {
             | Opt::GlintStrength
             | Opt::PanoramaSpeed => Kind::Slider(s.file.double(self.file_key().unwrap()) as f32),
             Opt::Fov => unit(s.fov, 30.0, 110.0),
-            Opt::RenderDistance => unit(s.render_distance as f32, 2.0, 64.0),
+            Opt::RenderDistance => unit(
+                s.render_distance as f32,
+                2.0,
+                crate::options_file::MAX_RENDER_DISTANCE as f32,
+            ),
             Opt::SimulationDistance => unit(s.simulation_distance as f32, 5.0, 32.0),
             Opt::Sensitivity => Kind::Slider(s.sensitivity),
             Opt::WheelSensitivity => unit(s.mouse_wheel_sensitivity, 0.01, 10.0),
@@ -308,6 +349,7 @@ 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 +398,14 @@ 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 +623,20 @@ 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",
@@ -586,6 +649,13 @@ impl Opt {
             Opt::ReducedDebugInfo => on_off(s.reduced_debug_info),
             Opt::HighContrast => on_off(s.high_contrast),
             Opt::ShowSubtitles => on_off(s.show_subtitles),
+            Opt::SoundDevice => {
+                if s.sound_device.is_empty() {
+                    tr("options.audioDevice.default")
+                } else {
+                    Text::literal(&s.sound_device)
+                }
+            }
             Opt::MusicFrequency => tr([
                 "options.music_frequency.default",
                 "options.music_frequency.frequent",
@@ -647,7 +717,10 @@ impl Opt {
                 crate::options_file::V::Double(f64::from(v)),
             ),
             Opt::Fov => s.fov = step(30.0, 110.0),
-            Opt::RenderDistance => s.render_distance = step(2.0, 64.0) as i32,
+            Opt::RenderDistance => {
+                s.render_distance =
+                    step(2.0, crate::options_file::MAX_RENDER_DISTANCE as f32) as i32
+            }
             Opt::SimulationDistance => s.simulation_distance = step(5.0, 32.0) as i32,
             Opt::Sensitivity => s.sensitivity = v,
             Opt::WheelSensitivity => s.mouse_wheel_sensitivity = 0.01 + v * 9.99,
@@ -674,6 +747,7 @@ 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 +844,14 @@ 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,
@@ -779,6 +860,23 @@ impl Opt {
             Opt::ReducedDebugInfo => s.reduced_debug_info = !s.reduced_debug_info,
             Opt::HighContrast => s.high_contrast = !s.high_contrast,
             Opt::ShowSubtitles => s.show_subtitles = !s.show_subtitles,
+            Opt::SoundDevice => {
+                let devices = crate::audio::output_devices();
+                let mut all = vec![String::new()];
+                for d in devices {
+                    if !all.contains(&d) {
+                        all.push(d);
+                    }
+                }
+                let current_idx = all.iter().position(|d| d == &s.sound_device).unwrap_or(0);
+                let count = all.len();
+                let next_idx = if back {
+                    (current_idx + count - 1) % count
+                } else {
+                    (current_idx + 1) % count
+                };
+                s.sound_device = all[next_idx].clone();
+            }
             Opt::MusicFrequency => {
                 let n = next(s.file.int("musicFrequency").clamp(0, 2) as u8, 3);
                 s.file
@@ -921,6 +1019,7 @@ pub enum Page {
     /// Horizon's graphics settings (`graphics_ui`).
     Graphics,
     GraphicsAdvanced,
+    GraphicsHdr,
     /// Horizon's controller settings and button binds.
     Controller,
     PadBinds,
@@ -955,8 +1054,7 @@ enum Act {
     /// Pick `s.shader_packs[i]`, or turn it off when it is the pick.
     PickShaderPack(usize),
     OpenShaderPackFolder,
-    /// The installed mod's own settings page (capability `ui`), shown as a
-    /// screen: `Event::ModSettings` has the game open it.
+    /// The installed native mod's settings page.
     ModSettings(usize),
     /// A native mod's key (mod, key) waits for a key; a button of its page.
     NativeKey(usize, usize),
@@ -1023,9 +1121,6 @@ pub enum Event {
     /// A shader pack was picked or turned off: save and apply it.
     ShaderPack,
     OpenShaderPackFolder,
-    /// 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),
@@ -1295,7 +1390,10 @@ impl OptionsUi {
         if page == Page::Packs {
             self.pack_screen = None;
         }
-        if matches!(page, Page::Graphics | Page::GraphicsAdvanced) {
+        if matches!(
+            page,
+            Page::Graphics | Page::GraphicsAdvanced | Page::GraphicsHdr
+        ) {
             self.graphics.reset();
         }
     }
@@ -1304,6 +1402,7 @@ impl OptionsUi {
         match page {
             Page::Graphics => Some(crate::graphics_ui::Level::Simple),
             Page::GraphicsAdvanced => Some(crate::graphics_ui::Level::Advanced),
+            Page::GraphicsHdr => Some(crate::graphics_ui::Level::Hdr),
             _ => None,
         }
     }
@@ -1325,7 +1424,7 @@ impl OptionsUi {
             Page::Mods => "Mods",
             Page::NativeMod(_) => "Mod Settings",
             Page::ShaderPacks => "Shader Packs",
-            Page::Graphics | Page::GraphicsAdvanced => "options.videoTitle",
+            Page::Graphics | Page::GraphicsAdvanced | Page::GraphicsHdr => "options.videoTitle",
             Page::Controller => "Controller Settings",
             Page::PadBinds => "Controller Binds",
             Page::Extras => "Horizon Extras",
@@ -1580,6 +1679,7 @@ impl OptionsUi {
                 rows.extend(pairs(&others));
                 rows.extend(pairs(&[Opt::ShowSubtitles, Opt::DirectionalAudio]));
                 rows.extend(pairs(&[Opt::MusicFrequency, Opt::MusicToast]));
+                rows.push(Row::Big(Opt::SoundDevice));
                 rows
             }
             Page::Skin => {
@@ -1615,11 +1715,8 @@ 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(
@@ -1714,9 +1811,9 @@ impl OptionsUi {
                             label = label.append(" (Dev)");
                         }
                         let dead = installed.dev || installed.id.is_empty();
-                        // A running mod with a settings page (capability
-                        // `ui`) gets its own button beside the toggle.
-                        if installed.has_settings || installed.native.is_some() {
+                        // A native mod gets its settings page's button beside
+                        // the toggle.
+                        if installed.native.is_some() {
                             let toggle = button(0.0, 0.0, 150.0, label, Act::ToggleMod(i));
                             let settings = button(
                                 0.0,
@@ -2587,6 +2684,7 @@ impl OptionsUi {
                     Action::Changed => events.push(Event::Changed),
                     Action::SliderDrag => events.push(Event::SliderDrag),
                     Action::OpenAdvanced => self.push(Page::GraphicsAdvanced),
+                    Action::OpenHdr => self.push(Page::GraphicsHdr),
                     Action::OpenSimple => {
                         if self.stack.len() >= 2
                             && self.stack[self.stack.len() - 2] == Page::Graphics
@@ -2772,12 +2870,8 @@ impl OptionsUi {
                         }
                         Act::ModSettings(i) => {
                             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));
-                            }
+                            self.push(Page::NativeMod(i));
+                            events.push(Event::NativeSettings(i));
                         }
                         Act::NativeKey(i, k) => {
                             self.selected_key = Some(NATIVE_KEY);
@@ -3223,10 +3317,48 @@ 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();
-        for (position, distance) in [(0.0, 2), (0.5, 33), (1.0, 64)] {
+        for (position, distance) in [(0.0, 2), (0.5, 65), (1.0, 128)] {
             set_slider(Opt::RenderDistance, &mut s, position);
             assert_eq!(s.render_distance, distance);
             let reloaded = Settings::parse(&s.serialize());
@@ -3237,10 +3369,10 @@ mod tests {
             );
         }
         let mut file = crate::options_file::OptionsFile::default();
-        file.set_text("renderDistance", "64").unwrap();
-        assert!(file.set_text("renderDistance", "65").is_err());
+        file.set_text("renderDistance", "128").unwrap();
+        assert!(file.set_text("renderDistance", "129").is_err());
         assert!(file.set_text("renderDistance", "1").is_err());
-        assert_eq!(file.int("renderDistance"), 64);
+        assert_eq!(file.int("renderDistance"), 128);
     }
     fn atlas() -> HudAtlas {
         HudAtlas::build(std::path::Path::new("/nonexistent/horizon-test-assets")).unwrap()
@@ -3348,7 +3480,6 @@ mod tests {
                 description: "May show HUD panels.".into(),
                 problem: id.is_empty().then(|| "Invalid package".into()),
                 dev,
-                has_settings: false,
                 native: None,
             });
         }
@@ -3416,7 +3547,6 @@ mod tests {
             description: String::new(),
             problem: None,
             dev: false,
-            has_settings: false,
             native: Some(crate::mod_list::NativePage::default()),
         });
         ui.show(Page::Mods);
@@ -4490,4 +4620,29 @@ mod tests {
         ui.stack = vec![Page::Main, Page::Controls];
         assert!(pushes(&mut ui).contains(&Page::Controller));
     }
+
+    #[test]
+    fn sound_device_button_in_sound_page_and_cycles() {
+        let mut s = Settings::default();
+        let mut ui = OptionsUi::default();
+        ui.show(Page::Sound);
+        let rows = ui.list_rows(&s);
+        assert!(
+            rows.iter().any(|r| matches!(r, Row::Big(Opt::SoundDevice))),
+            "Sound page should contain Row::Big(Opt::SoundDevice)"
+        );
+        assert_eq!(s.sound_device, "");
+        let devices = crate::audio::output_devices();
+        let count = 1 + devices.len();
+        // Cycling forward 'count' times wraps around back to the initial selection ("")
+        for _ in 0..count {
+            Opt::SoundDevice.cycle(&mut s, false, [854, 480]);
+        }
+        assert_eq!(s.sound_device, "");
+        // Cycling backward 'count' times also wraps around back to ""
+        for _ in 0..count {
+            Opt::SoundDevice.cycle(&mut s, true, [854, 480]);
+        }
+        assert_eq!(s.sound_device, "");
+    }
 }

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

@@ -3,7 +3,6 @@
 use super::{Pack, Source, build_overlay_uncached};
 use serde::{Deserialize, Serialize};
 use sha2::{Digest, Sha256};
-#[cfg(any(test, not(unix)))]
 use std::io::Read;
 use std::{collections::BTreeSet, fs, io, path::Path, path::PathBuf};
 
@@ -60,7 +59,6 @@ fn field(hash: &mut Sha256, bytes: &[u8]) {
     hash.update((bytes.len() as u64).to_le_bytes());
     hash.update(bytes);
 }
-#[cfg(any(test, not(unix)))]
 fn content(hash: &mut Sha256, path: &Path) -> io::Result<()> {
     let mut file = fs::File::open(path)?;
     hash.update(file.metadata()?.len().to_le_bytes());
@@ -238,7 +236,10 @@ fn pack_signature(packs: &[Pack]) -> io::Result<String> {
             }
             Source::Zip(path) => {
                 field(&mut hash, absolute(path)?.as_os_str().as_encoded_bytes());
-                stamp(&mut hash, path)?;
+                // By its bytes, not its stamp: a server pack found in the download cache is
+                // marked used on every join (`HttpUtil.updateModificationTime`), and a new
+                // time rebuilt the whole overlay each time. One file reads in a moment.
+                content(&mut hash, path)?;
             }
         }
     }
@@ -349,6 +350,27 @@ 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"),
@@ -371,6 +393,7 @@ mod tests {
                 output_signature(&cached).unwrap(),
                 output_signature(&self.0.join("reference")).unwrap()
             );
+            self.next_tick();
         }
     }
     impl Drop for Fixture {
@@ -647,6 +670,38 @@ mod tests {
         );
     }
 
+    /// A ZIP whose bytes are the same keeps its overlay when only its time changes: a server
+    /// pack found in the download cache is marked used on every join
+    /// (`HttpUtil.updateModificationTime`), and rebuilding the overlay took most of a minute.
+    #[test]
+    fn a_zip_touched_but_unchanged_keeps_its_overlay() {
+        let f = Fixture::new();
+        f.write("vanilla/assets/minecraft/textures/b", b"vanilla");
+        let files = vec![
+            (
+                "pack.mcmeta",
+                br#"{"pack":{"description":"test","pack_format":97}}"#.to_vec(),
+            ),
+            ("assets/minecraft/textures/a", b"aaa".to_vec()),
+        ];
+        f.write("pack.zip", &archive(&files, false));
+        let zip = f.0.join("pack.zip");
+        let pack = packs::pack("zip".into(), Text::empty(), Source::Zip(zip.clone())).unwrap();
+        let (vanilla, out) = (f.0.join("vanilla"), f.0.join("cached"));
+        packs::build_overlay(&vanilla, std::slice::from_ref(&pack), &out).unwrap();
+        // A rebuild empties the output first: this file survives a cache hit only.
+        fs::write(out.join("kept"), b"").unwrap();
+        let later = std::time::SystemTime::now() + std::time::Duration::from_secs(60);
+        fs::OpenOptions::new()
+            .append(true)
+            .open(&zip)
+            .unwrap()
+            .set_modified(later)
+            .unwrap();
+        packs::build_overlay(&vanilla, std::slice::from_ref(&pack), &out).unwrap();
+        assert!(out.join("kept").exists(), "the overlay was rebuilt");
+    }
+
     #[cfg(unix)]
     #[test]
     fn unrelated_directory_pack_symlink_cycle_disables_reuse() {

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

@@ -101,6 +101,8 @@ pub struct Settings {
     pub master_volume: f32,
     /// Volumes of every other sound source, indexed like SOUND_SOURCES.
     pub volumes: [f32; 11],
+    /// Empty for system default, or a specific audio device name.
+    pub sound_device: String,
     /// Requested scale (0 = auto); rendering caps it to the current framebuffer.
     pub gui_scale: u32,
     pub view_bobbing: bool,
@@ -174,6 +176,12 @@ 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).
@@ -195,6 +203,7 @@ impl Default for Settings {
             sensitivity: 0.5,
             master_volume: 1.0,
             volumes: [1.0; 11],
+            sound_device: String::new(),
             gui_scale: 0,
             view_bobbing: true,
             gamma: 0.5,
@@ -256,6 +265,9 @@ 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(),
@@ -383,6 +395,7 @@ impl Settings {
             sensitivity: f.double("mouseSensitivity") as f32,
             master_volume: volumes[0],
             volumes,
+            sound_device: f.string("soundDevice"),
             gui_scale: f.int("guiScale").max(0) as u32,
             view_bobbing: f.bool("bobView"),
             gamma: f.double("gamma") as f32,
@@ -418,6 +431,9 @@ 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(),
@@ -475,6 +491,7 @@ impl Settings {
             };
             put_f(&mut f, &format!("soundCategory_{source}"), v);
         }
+        put_s(&mut f, "soundDevice", &self.sound_device);
         put_i(&mut f, "guiScale", self.gui_scale as i32);
         put_b(&mut f, "bobView", self.view_bobbing);
         put_f(&mut f, "gamma", self.gamma);
@@ -518,6 +535,13 @@ 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);
@@ -637,6 +661,7 @@ pub enum Opt {
     InvertY,
     AllowCursorChanges,
     Volume(usize),
+    SoundDevice,
     GuiScale,
     ViewBobbing,
     Gamma,
@@ -664,7 +689,13 @@ pub enum Opt {
     MenuBlur,
     ToggleCrouch,
     ToggleSprint,
+    ToggleAttack,
+    ToggleUse,
     AutoJump,
+    SprintWindow,
+    QuitShortcuts,
+    CtrlClickEmulatesRightClick,
+    OperatorItemsTab,
     ChatVisibility,
     ChatColors,
     ChatLinks,
@@ -820,4 +851,15 @@ mod tests {
             1.0
         );
     }
+    #[test]
+    fn sound_device_option() {
+        let s = Settings::parse("soundDevice:\"Headphones\"\n");
+        assert_eq!(s.sound_device, "Headphones");
+        let serialized = s.serialize();
+        assert!(serialized.contains("soundDevice:\"Headphones\""));
+        let again = Settings::parse(&serialized);
+        assert_eq!(again.sound_device, "Headphones");
+        let empty = Settings::parse("");
+        assert_eq!(empty.sound_device, "");
+    }
 }

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

@@ -13,11 +13,10 @@ use horizon_core::biome::BiomeZoom;
 use horizon_world::block_render::FaceVisibility;
 use horizon_world::worldgen::decoration_order::DecorationOrder;
 use std::{
-    collections::{BinaryHeap, HashSet},
+    collections::{BinaryHeap, HashSet, VecDeque},
     sync::{
-        Arc, Condvar, Mutex, RwLock,
+        Arc, Condvar, Mutex, MutexGuard, RwLock, TryLockError,
         atomic::{AtomicBool, Ordering},
-        mpsc,
     },
     thread,
 };
@@ -171,6 +170,9 @@ 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),
@@ -217,11 +219,52 @@ struct Shared {
     /// What meshing reads (block models and sprites), swapped when resource
     /// packs reload; each mesh job takes the current one.
     context: RwLock<Arc<WorkerContext>>,
+    done: Mailbox,
+}
+/// Finished jobs, from the workers to the game thread, in the order they
+/// finished. Not an `mpsc` channel: its receiver waits for a sender it finds
+/// half way through a send, and a worker descheduled there on a busy machine
+/// held the frame for a scheduler quantum (10 to 30 ms, the RD 32 ocean
+/// flight's 1% lows). The frame takes what is there without waiting; while a
+/// worker holds the lock, it takes it the next frame.
+#[derive(Default)]
+struct Mailbox {
+    done: Mutex<VecDeque<Done>>,
+    arrived: Condvar,
+}
+impl Mailbox {
+    fn send(&self, done: Done) {
+        self.done.lock().unwrap().push_back(done);
+        self.arrived.notify_one();
+    }
+    fn try_lock(&self) -> Option<MutexGuard<'_, VecDeque<Done>>> {
+        match self.done.try_lock() {
+            Ok(done) => Some(done),
+            Err(TryLockError::WouldBlock) => None,
+            Err(TryLockError::Poisoned(e)) => panic!("{e}"),
+        }
+    }
+    /// Every finished job, or none while a worker is sending.
+    fn take(&self) -> VecDeque<Done> {
+        self.try_lock()
+            .map(|mut done| std::mem::take(&mut *done))
+            .unwrap_or_default()
+    }
+    fn try_recv(&self) -> Option<Done> {
+        self.try_lock()?.pop_front()
+    }
+    fn recv_timeout(&self, timeout: std::time::Duration) -> Option<Done> {
+        let done = self.done.lock().unwrap();
+        let (mut done, _) = self
+            .arrived
+            .wait_timeout_while(done, timeout, |done| done.is_empty())
+            .unwrap();
+        done.pop_front()
+    }
 }
 pub struct Streaming {
     shared: Arc<Shared>,
     light_view: Arc<dyn Fn(&Proto) -> Option<Chunk> + Send + Sync>,
-    results: mpsc::Receiver<Done>,
     threads: Vec<thread::JoinHandle<()>>,
     order: u64,
     /// Ticks since the columns and protos that fell out of range were swept.
@@ -458,14 +501,13 @@ impl Streaming {
             ready: Condvar::new(),
             stop: AtomicBool::new(false),
             context: RwLock::new(context.clone()),
+            done: Mailbox::default(),
         });
-        let (send, results) = mpsc::channel();
         let light_tables = context.light.clone();
         let saves: Arc<dyn Saves> = generator.clone();
         let threads = (0..threads.max(1))
             .map(|i| {
                 let shared = shared.clone();
-                let send = send.clone();
                 let generator = generator.clone();
                 let light = context.light.clone();
                 thread::Builder::new()
@@ -513,6 +555,10 @@ 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)
                                 }
@@ -544,9 +590,7 @@ impl Streaming {
                                     Done::Meshed(x, sy, z, mesh, seq)
                                 }
                             };
-                            if send.send(done).is_err() {
-                                return;
-                            }
+                            shared.done.send(done);
                         }
                     })
                     .expect("spawn worker")
@@ -559,7 +603,6 @@ impl Streaming {
         Self {
             shared,
             light_view,
-            results,
             threads,
             order: 0,
             scan_age: 0,
@@ -663,6 +706,17 @@ 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));
@@ -679,7 +733,7 @@ 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);
@@ -912,8 +966,10 @@ impl Streaming {
         self.requeue();
         self.relight_edits(world);
         let deferred = std::mem::take(&mut self.deferred);
-        let received = std::iter::from_fn(|| self.results.try_recv().ok());
-        for done in deferred.into_iter().chain(received.collect::<Vec<_>>()) {
+        let received = self.shared.done.take();
+        // Meshes made stale meanwhile, freed with the uploaded ones (`free`).
+        let mut stale = Vec::new();
+        for done in deferred.into_iter().chain(received) {
             match done {
                 Done::Proto(x, z, proto, decorated) => {
                     self.generation_scan.exhausted = false;
@@ -969,12 +1025,14 @@ 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));
@@ -983,6 +1041,7 @@ impl Streaming {
                 }
             }
         }
+        self.free(stale);
         let mut removed = Vec::new();
         if sweep {
             // Unload far columns.
@@ -1421,12 +1480,12 @@ impl Streaming {
         let deadline = std::time::Instant::now() + std::time::Duration::from_secs(30);
         while self.decorating > 0 || !self.finishing.is_empty() || self.saving > 0 {
             let left = deadline.saturating_duration_since(std::time::Instant::now());
-            match self.results.recv_timeout(left) {
-                Ok(Done::Decorated(x, z, region)) => self.receive_decorated(x, z, *region),
-                Ok(Done::Generated(chunk)) => self.receive_generated(chunk, world),
-                Ok(Done::Saved(protos)) => self.receive_saved(protos),
-                Ok(other) => self.deferred.push(other),
-                Err(_) => {
+            match self.shared.done.recv_timeout(left) {
+                Some(Done::Decorated(x, z, region)) => self.receive_decorated(x, z, *region),
+                Some(Done::Generated(chunk)) => self.receive_generated(chunk, world),
+                Some(Done::Saved(protos)) => self.receive_saved(protos),
+                Some(other) => self.deferred.push(other),
+                None => {
                     log::warn!("Horizon: chunk generation did not finish before saving");
                     break;
                 }
@@ -1448,7 +1507,7 @@ impl Streaming {
     /// in `save(true)`, so older generation cannot overwrite the final chunks.
     pub fn poll_save(&mut self, world: &mut World) -> bool {
         let started = std::time::Instant::now();
-        while let Ok(done) = self.results.try_recv() {
+        while let Some(done) = self.shared.done.try_recv() {
             match done {
                 Done::Decorated(x, z, region) => self.receive_decorated(x, z, *region),
                 Done::Generated(chunk) => self.receive_generated(chunk, world),
@@ -1533,7 +1592,7 @@ impl Streaming {
     /// Wait up to `timeout` for a worker to finish a job; the next `update`
     /// takes it. A server pumps generation with this between its ticks.
     pub fn wait(&mut self, timeout: std::time::Duration) {
-        if let Ok(done) = self.results.recv_timeout(timeout) {
+        if let Some(done) = self.shared.done.recv_timeout(timeout) {
             self.deferred.push(done);
         }
     }
@@ -1814,10 +1873,10 @@ impl Drop for Streaming {
         let deadline = std::time::Instant::now() + std::time::Duration::from_secs(30);
         while self.saving > 0 {
             let left = deadline.saturating_duration_since(std::time::Instant::now());
-            match self.results.recv_timeout(left) {
-                Ok(Done::Saved(_)) => self.saving -= 1,
-                Ok(_) => {}
-                Err(_) => break,
+            match self.shared.done.recv_timeout(left) {
+                Some(Done::Saved(_)) => self.saving -= 1,
+                Some(_) => {}
+                None => break,
             }
         }
         self.shared.stop.store(true, Ordering::Relaxed);
@@ -1855,6 +1914,37 @@ fn rank_again(queue: &mut BinaryHeap<Queued>, distance: impl Fn(i32, i32) -> i64
 mod tests {
     use super::*;
 
+    /// The frame never waits for a worker: while one holds the mailbox, the
+    /// frame takes nothing and finds the results, in order, the next time.
+    #[test]
+    fn the_frame_takes_finished_jobs_without_waiting() {
+        let mailbox = Mailbox::default();
+        let lit = |seq| Done::Lit(0, 0, Vec::new(), seq);
+        mailbox.send(lit(1));
+        mailbox.send(lit(2));
+        let sending = mailbox.done.lock().unwrap();
+        assert!(mailbox.take().is_empty());
+        assert!(mailbox.try_recv().is_none());
+        drop(sending);
+        let seqs: Vec<u64> = mailbox
+            .take()
+            .into_iter()
+            .map(|done| match done {
+                Done::Lit(_, _, _, seq) => seq,
+                _ => unreachable!(),
+            })
+            .collect();
+        assert_eq!(seqs, [1, 2]);
+        assert!(mailbox.take().is_empty());
+        let waiting = std::time::Instant::now();
+        assert!(
+            mailbox
+                .recv_timeout(std::time::Duration::from_millis(10))
+                .is_none()
+        );
+        assert!(waiting.elapsed() >= std::time::Duration::from_millis(10));
+    }
+
     #[test]
     fn queued_jobs_follow_the_centre_and_the_loading_screen() {
         let forced = HashSet::new();

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/Cargo.toml

@@ -91,9 +91,6 @@ default = ["audio", "controllers"]
 audio = ["horizon-client-render/audio"]
 # Controllers: gilrs, and the DualSense's own output. Without it only `horizon-ctl pad`'s virtual pad.
 controllers = ["dep:gilrs", "dep:horizon-dualsense", "horizon-client-input/controllers"]
-# Runs code mods (wasmtime and cranelift: a quarter of a clean build). On in every release build
-# (release.yml); the tests and probes don't need it. Content mods load without it.
-mods = ["horizon-mods/runtime"]
 # Records the call sites of mob random draws (`mob_ai_probe` traces).
 rng-trace = ["horizon-core/rng-trace"]
 

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/main.rs

@@ -88,6 +88,7 @@ mod sound_event_fixture;
 mod spawn_rules_fixture;
 mod sprint_probe;
 mod squid_client_probe;
+mod storage_menu_fixture;
 mod subtitle_fixture;
 mod tab_list_fixture;
 mod team_rules_fixture;
@@ -179,6 +180,7 @@ probes! {
     sound_event_fixture,
     spawn_rules_fixture,
     sprint_probe,
+    storage_menu_fixture,
     subtitle_fixture,
     tab_list_fixture,
     team_rules_fixture,

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

@@ -0,0 +1,37 @@
+//! Storage block menus for tools/test_storage_menu_parity.py: reads one
+//! block id per line and prints the menu type the server opens it with
+//! (`horizon_client::containers::block_menu_type`, as `lan_open_container`
+//! sends it) and whether that menu's slots take a shulker box: the server
+//! refuses them in a `minecraft:shulker_box` menu (`ShulkerBoxSlot.mayPlace`,
+//! `lan::containers`).
+//!
+//! usage: storage_menu_fixture INPUT OUTPUT
+use horizon_client::containers::block_menu_type;
+use std::fs;
+
+fn case(block: &str) -> Option<String> {
+    let menu = block_menu_type(block.trim())?;
+    let accepts = if menu == "minecraft:shulker_box" {
+        "refuses"
+    } else {
+        "accepts"
+    };
+    Some(format!("{menu} {accepts} shulker_box"))
+}
+
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
+    let input = fs::read_to_string(
+        args.get(1)
+            .ok_or("usage: storage_menu_fixture INPUT OUTPUT")?,
+    )?;
+    let lines: Vec<String> = input
+        .lines()
+        .map(|line| case(line).unwrap_or_else(|| "error".to_owned()))
+        .collect();
+    fs::write(
+        args.get(2).ok_or("missing OUTPUT")?,
+        lines.join("\n") + "\n",
+    )?;
+    Ok(())
+}

crates/horizon-client/src/bin/horizon-ctl/commands.rs

@@ -146,6 +146,7 @@ const PAGES: Ty = Ty::Enum(&[
     "shader-packs",
     "graphics",
     "graphics-advanced",
+    "graphics-hdr",
     "extras",
     "horizon",
     "agent",
@@ -425,7 +426,7 @@ pub const COMMANDS: &[Cmd] = &[
         &[BOX[0], BOX[1], BOX[2], BOX[3], BOX[4], BOX[5], p("block", Ty::Str, "block state")], mcp: true, local: false),
     cmd!("container", World, "container X Y Z [ITEM COUNT]", "list a container's items, or add items to it", "", ["horizon-ctl container 3 64 1", "horizon-ctl container 3 64 1 diamond 3"],
         &[BLOCK_XYZ[0], BLOCK_XYZ[1], BLOCK_XYZ[2], opt("item", Ty::Str, "item to add"), opt("count", Ty::Int, "how many")], mcp: true, local: false),
-    cmd!("render-distance", World, "render-distance N", "chunks, 2..64", "", ["horizon-ctl render-distance 8"], &[p("chunks", Ty::Int, "render distance")], mcp: false, local: false),
+    cmd!("render-distance", World, "render-distance N", "chunks, 2..128", "", ["horizon-ctl render-distance 8"], &[p("chunks", Ty::Int, "render distance")], mcp: false, local: false),
     cmd!("wait", World, "wait TICKS", "wait until TICKS game ticks have passed (20 per second)",
         "Keys and mouse buttons held with key ... down or mouse ... down stay held while it waits. Release them with key ... up, release or stop.",
         ["horizon-ctl wait 40", "horizon-ctl key w down && horizon-ctl wait 40 && horizon-ctl key w up"],

crates/horizon-client/src/game.rs

@@ -110,14 +110,9 @@ mod minecarts;
 mod mob_blocks;
 mod mob_gear;
 mod mob_sounds;
-mod mod_input;
-#[cfg(feature = "mods")]
-mod mod_panel;
-mod mod_render;
 mod mods;
 mod mount_menu;
 mod mounts;
-mod moved_extras;
 mod moving_pistons;
 mod music;
 mod names;
@@ -170,7 +165,6 @@ mod screens;
 mod sculk;
 mod sculk_fixture;
 mod server_links;
-mod server_mods;
 mod server_packs;
 mod server_travel;
 mod shader_packs;
@@ -326,15 +320,24 @@ struct Options {
     dedicated: Option<Vec<String>>,
     /// `--benchmark SCENARIO`: run the benchmark, write its report and quit.
     benchmark: Option<String>,
-    /// `--dev-mod PATH` (repeatable): mods always on and reloaded when rebuilt.
+    /// `--dev-mod PATH` (repeatable): content mods always on.
     dev_mods: Vec<PathBuf>,
     /// Single player runs on an integrated server thread (game/integrated.rs),
     /// as vanilla's does: the default. `--in-frame` (or `--no-server-thread`,
     /// or `HORIZON_SERVER_THREAD=0`) runs the world in the frame instead.
+    /// DEPRECATED: never use it; it is unsupported and will be removed soon.
     server_thread: bool,
     /// What this Game executes; independent of its current server connection.
     execution_role: execution_role::ExecutionRole,
 }
+/// `--in-frame`, `--no-server-thread` and `HORIZON_SERVER_THREAD=0` are deprecated:
+/// the in-frame world is unmaintained, gets no fixes and will be removed soon.
+fn warn_in_frame_deprecated(what: &str) {
+    eprintln!(
+        "Horizon: DEPRECATED: {what} runs single player's world in the window, a path that is no longer supported, \
+         gets no fixes and will be removed soon. Do not use it: single player runs on its server thread by default."
+    );
+}
 impl Options {
     /// The name to join servers with: the one given, else the offline name kept
     /// next to options.txt (created on first use).
@@ -386,7 +389,13 @@ impl Options {
             dedicated: None,
             benchmark: None,
             dev_mods: Vec::new(),
-            server_thread: std::env::var("HORIZON_SERVER_THREAD").map_or(true, |v| v != "0"),
+            server_thread: std::env::var("HORIZON_SERVER_THREAD").map_or(true, |v| {
+                let on = v != "0";
+                if !on {
+                    warn_in_frame_deprecated("HORIZON_SERVER_THREAD=0");
+                }
+                on
+            }),
             execution_role: execution_role::ExecutionRole::Client,
         };
         let mut session_file = std::env::var("HORIZON_SESSION_FILE").ok();
@@ -395,7 +404,7 @@ impl Options {
             match arg.as_str() {
                 "--help" | "-h" => {
                     println!(
-                        "Horizon — Minecraft Java Edition {} in Rust\n\n  --resources PATH        Prepared resources (horizon-prepare)\n  --render-distance N     Chunks, 2..64 (default 12)\n  --world NAME            World folder under saves/ (default \"New World\")\n  --seed N                World seed for new worlds (default 0)\n  --width N, --height N   Window size (default 1280 x 720)\n  --creative              Creative mode (default survival)\n  --test-terrain          Simple test terrain instead of vanilla generation\n  --frames N              Exit after N frames (testing)\n  --world-frames N        Exit after N frames drawn in the world (testing)\n  --smoke-report PATH     Write a JSON report on exit\n  --benchmark SCENARIO    Run a benchmark (standard, village, forest, ocean, mountain), write its report to benchmarks/ and quit\n  --control               Accept horizon-ctl commands on a local socket\n  --control-socket PATH   Control socket path (default $XDG_RUNTIME_DIR/horizon-control.sock)\n  --server HOST[:PORT]    Join a multiplayer server (offline mode) at start\n  --quickPlaySingleplayer WORLD  Open this world of saves/ at start, only if it exists (vanilla's)\n  --quickPlayMultiplayer HOST[:PORT]  The same as --server (vanilla's name)\n  --name NAME             Player name for multiplayer (default: generated once, kept in horizon-player.txt)\n  --session-file PATH     Signed-in account from the launcher (read once, then deleted)\n  --dev-mod PATH          A Horizon mod (.hmod or folder) to develop: always on, reloaded when rebuilt\n  --in-frame              Run single player's world in the frame, not on its server thread\n  --pregen                Add Horizon's /pregen command (docs/pregeneration.md)\n\nControls: mouse look, WASD move, Space jump, Left Shift sneak, Left Ctrl sprint,\nleft click break, right click place/use, 1-9/scroll hotbar, E inventory,\nQ drop, F3 debug, Esc pause.",
+                        "Horizon — Minecraft Java Edition {} in Rust\n\n  --resources PATH        Prepared resources (horizon-prepare)\n  --render-distance N     Chunks, 2..128 (default 12)\n  --world NAME            World folder under saves/ (default \"New World\")\n  --seed N                World seed for new worlds (default 0)\n  --width N, --height N   Window size (default 1280 x 720)\n  --creative              Creative mode (default survival)\n  --test-terrain          Simple test terrain instead of vanilla generation\n  --frames N              Exit after N frames (testing)\n  --world-frames N        Exit after N frames drawn in the world (testing)\n  --smoke-report PATH     Write a JSON report on exit\n  --benchmark SCENARIO    Run a benchmark (standard, village, forest, ocean, mountain), write its report to benchmarks/ and quit\n  --control               Accept horizon-ctl commands on a local socket\n  --control-socket PATH   Control socket path (default $XDG_RUNTIME_DIR/horizon-control.sock)\n  --server HOST[:PORT]    Join a multiplayer server (offline mode) at start\n  --quickPlaySingleplayer WORLD  Open this world of saves/ at start, only if it exists (vanilla's)\n  --quickPlayMultiplayer HOST[:PORT]  The same as --server (vanilla's name)\n  --name NAME             Player name for multiplayer (default: generated once, kept in horizon-player.txt)\n  --session-file PATH     Signed-in account from the launcher (read once, then deleted)\n  --dev-mod PATH          A content mod (.hmod or folder) to develop: always on\n  --in-frame              DEPRECATED, do not use: unsupported, will be removed soon (also --no-server-thread)\n  --pregen                Add Horizon's /pregen command (docs/pregeneration.md)\n\nControls: mouse look, WASD move, Space jump, Left Shift sneak, Left Ctrl sprint,\nleft click break, right click place/use, 1-9/scroll hotbar, E inventory,\nQ drop, F3 debug, Esc pause.",
                         horizon_core::VANILLA_VERSION
                     );
                     return Ok(None);
@@ -411,7 +420,10 @@ impl Options {
                 "--offscreen" => o.offscreen = true,
                 "--control" => o.control = Some(horizon_client::control::default_path()),
                 "--server-thread" => o.server_thread = true,
-                "--in-frame" | "--no-server-thread" => o.server_thread = false,
+                "--in-frame" | "--no-server-thread" => {
+                    warn_in_frame_deprecated(&arg);
+                    o.server_thread = false;
+                }
                 // Horizon's own commands (/pregen), off by default as on vanilla.
                 "--pregen" => horizon_client::command::vanilla::set_horizon_commands(true),
                 _ => {
@@ -423,8 +435,9 @@ impl Options {
                         "--render-distance" | "--radius" => {
                             o.distance = value.parse()?;
                             o.distance_override = Some(o.distance);
-                            if !(2..=64).contains(&o.distance) {
-                                return Err("render distance must be 2..64".into());
+                            let max = horizon_client::options_file::MAX_RENDER_DISTANCE;
+                            if !(2..=max).contains(&o.distance) {
+                                return Err(format!("render distance must be 2..{max}").into());
                             }
                         }
                         "--seed" => {
@@ -535,9 +548,6 @@ enum Screen {
     DialogWarning,
     /// WinScreen: the end poem and the credits (game/win.rs).
     Win,
-    /// A `ui` mod's own screen, or its settings page from Options > Mods
-    /// (game/mods.rs).
-    Mod,
 }
 struct Mining {
     pos: [i32; 3],
@@ -1419,6 +1429,14 @@ fn select_creative_tab(
     clicks.skip_release();
 }
 
+/// The icon the Select World list shows for the world in play
+/// (`GameRenderer.tryTakeScreenshotIfNeeded`): its path in the save, and when
+/// the last frame grab was asked for.
+struct WorldIcon {
+    path: PathBuf,
+    last_attempt: Option<Instant>,
+}
+
 struct Game<'a> {
     /// Shared with an integrated server; `collision` and `motion` borrow from it.
     res: Arc<Resources>,
@@ -1507,12 +1525,17 @@ struct Game<'a> {
     keys: HashSet<KeyCode>,
     // Physical input is separate from remapped and toggled movement keys.
     physical_keys: HashSet<KeyCode>,
+    physical_buttons: HashSet<MouseButton>,
     left: bool,
     right: bool,
     cursor: (f32, f32),
     /// The cursor icon the window shows (`widgets::take_cursor` each frame).
     cursor_icon: horizon_client::widgets::Cursor,
     captured: bool,
+    /// Only the local player owning keyboard and mouse changes the native pointer.
+    keyboard_mouse: bool,
+    /// This view's corner in its shared window; cursor warps include the offset.
+    view_at: [u32; 2],
     focused: bool,
     /// When the window lost focus, while it is still without
     /// (`Minecraft.lastActiveTime`: pausing waits 500 ms).
@@ -1919,6 +1942,9 @@ struct Game<'a> {
     /// The world was saved for the application ending (`save_for_exit`).
     saved_for_exit: bool,
     pending_save: Option<saving::ClosingSave>,
+    /// The world list's icon in progress (`GameRenderer.tryTakeScreenshotIfNeeded`):
+    /// `None` without a local world, or once the save has its icon.png.
+    world_icon: Option<WorldIcon>,
     /// The block a guest is acting on (game/lan_actions.rs).
     forced_hit: Option<Hit>,
     /// The part of a right click a guest's packet asks for (game/lan_actions.rs).
@@ -4173,9 +4199,6 @@ impl Game<'_> {
                 correct_tool,
             )
         });
-        if removed {
-            self.mod_block_event(pos, broken, false);
-        }
         if removed && !creative {
             let held = self.held().cloned();
             self.mine_block_with_held(&facts.name, facts.hardness);
@@ -4638,7 +4661,6 @@ impl Game<'_> {
         };
         let target = [pos.x, pos.y, pos.z];
         let state = self.apply_item_block_state(target, state, &stack)?;
-        self.mod_block_event(target, state, true);
         if let Some(entity) = BlockEntity::for_block(&self.res.facts().get(state).name) {
             let key = (target[0], target[1], target[2]);
             self.world.block_entities.insert(key, entity);
@@ -5280,9 +5302,8 @@ impl Game<'_> {
         self.tick_totem();
         self.update_totem_ready();
         self.tick_command_extras();
-        self.tick_mods();
         self.native_tick();
-        self.tick_server_mods();
+        self.tell_native_now();
         let camera_eye = self.camera_eye_height();
         let stick = self.pad_move();
         if self.riding.is_some() && self.player.is_some() {
@@ -5304,6 +5325,7 @@ impl Game<'_> {
         let riding = self.riding.is_some();
         let entity_collisions = self.player_entity_collisions();
         let spin_targets = self.spin_targets();
+        let sprint_window = self.settings.sprint_window;
         self.sync_player_body();
         let Some(player) = self.player.as_mut() else {
             // A dedicated server has no local player: the world still runs.
@@ -5356,7 +5378,7 @@ impl Game<'_> {
                 collision_binding: self.collision,
                 resources: self.motion,
             }
-            .controlled_simulation_tick(keys)?;
+            .controlled_simulation_tick_with_sprint_window(keys, sprint_window)?;
             // Player.jumpFromGround: the jump statistic.
             if grounded && keys.jump && !player.flying && player.velocity.y > 0.2 {
                 self.stats.custom("jump", 1);
@@ -5912,13 +5934,21 @@ impl Game<'_> {
         }
         // The real pointer takes over from an agent's.
         self.agent_pointer = false;
+        // Splitscreen: another player has the pointer; this one's menus leave it alone.
+        if !self.keyboard_mouse {
+            self.captured = false;
+            return;
+        }
         let Some(window) = &self.window else { return };
         let size = self.renderer.as_ref().map_or_else(
             || window.inner_size().into(),
             |r| [r.config.width, r.config.height],
         );
-        let centre =
-            winit::dpi::PhysicalPosition::new(f64::from(size[0]) / 2.0, f64::from(size[1]) / 2.0);
+        let [vx, vy] = self.view_at.map(f64::from);
+        let centre = winit::dpi::PhysicalPosition::new(
+            vx + f64::from(size[0]) / 2.0,
+            vy + f64::from(size[1]) / 2.0,
+        );
         let warp = |window: &Window| {
             let _ = window.set_cursor_position(centre);
         };
@@ -5984,7 +6014,7 @@ impl Game<'_> {
         } else {
             Cursor::Arrow
         };
-        if effective == self.cursor_icon {
+        if effective == self.cursor_icon || !self.keyboard_mouse {
             return;
         }
         if let Some(window) = &self.window {
@@ -6256,7 +6286,6 @@ impl Game<'_> {
             // Hud: the action bar and titles draw over the hotbar (nextStratum).
             self.draw_boss_bars(&mut batch);
             self.draw_extras(&mut batch);
-            self.draw_mod_shapes(&mut batch);
         }
         if show_hud {
             // Hud.nextContextualInfoState: the jump bar, the experience bar or
@@ -6435,7 +6464,6 @@ impl Game<'_> {
                 self.draw_creative(&mut batch);
             }
             Screen::Chat => self.draw_chat_screen(&mut batch),
-            Screen::Mod => self.draw_mod_screen(&mut batch),
             Screen::Playing | Screen::Options | Screen::Win => {}
         }
         self.draw_saving_indicator(&mut batch);
@@ -6929,6 +6957,9 @@ impl Game<'_> {
                 self.inventory[i] = Some(stack);
             }
             DisplayClick::Offhand(stack) => self.offhand = Some(stack),
+            // handleCreativeModeItemDrop: on a server the stack goes to it (SetCreativeModeSlot
+            // to slot -1), which drops it; a local drop here would never reach the server.
+            DisplayClick::Drop(stack) if self.remote.is_some() => self.remote_creative_throw(stack),
             DisplayClick::Drop(stack) => self.player_drop(stack),
             _ => {}
         }
@@ -9338,6 +9369,12 @@ impl Game<'_> {
         book.to_be_displayed.retain(|r| index.contains(r));
         self.dim = dim;
         self.world_root = save_root.clone();
+        // LevelStorageAccess.getIconFile: this save's icon.png is what the
+        // Select World list shows.
+        self.world_icon = Some(WorldIcon {
+            path: save_root.join("icon.png"),
+            last_attempt: None,
+        });
         self.world_flat = horizon_client::save::WorldGen::read(&save_root).is_some_and(|w| w.flat);
         self.block_ticks = Ticks::new(self.level.seed as i32);
         self.tick_chunks.clear();
@@ -9664,10 +9701,12 @@ impl Game<'_> {
         self.music.stop_playing(None, &mut self.audio);
         self.audio.stop_all();
         if self.remote.is_some() {
+            self.world_icon = None;
             return self.leave_server(None);
         }
         // The save screen has finished every write before releasing storage.
         self.session_lock = None;
+        self.world_icon = None;
         horizon_client::crash::clear_detail("World");
         self.debug_charts.reset();
         self.boss_overlay.reset();
@@ -9693,6 +9732,7 @@ impl Game<'_> {
         ));
         if let Some(title) = &mut self.title {
             title.last_server = self.settings.file.string("lastServer");
+            title.skip_multiplayer_warning = self.settings.file.bool("skipMultiplayerWarning");
         }
         self.capture(false);
         Ok(())
@@ -10674,10 +10714,13 @@ impl Game<'_> {
             .unwrap_or_else(|| ItemStack::new("minecraft:arrow", 1));
         let weapon = self.held().cloned();
         let (power_bonus, infinity) = self.bow_enchantments(&ammo.item);
+        let effect = dispenser::tipped_effect(&ammo).or_else(|| {
+            (&*ammo.item == "minecraft:spectral_arrow").then_some(("minecraft:glowing", 200))
+        });
         let kind = horizon_client::projectiles::ProjectileKind::Arrow {
             base_damage: 2.0 + power_bonus,
             critical: power >= 1.0,
-            effect: None,
+            effect,
         };
         let mut arrow = horizon_client::projectiles::Projectile::new(
             kind,
@@ -10822,14 +10865,16 @@ impl Game<'_> {
             // The main hand on its arm, the off hand on the other one.
             let left = self.settings.main_hand_left != (hand == Hand::Off);
             let Some(stack) = item else {
-                // Only the main hand's empty arm shows.
-                if hand == Hand::Off {
+                // renderArmWithItem: only the main hand's empty arm shows,
+                // on the main arm (the left one with the main hand set to
+                // left), and not while the player is invisible.
+                if hand == Hand::Off || self.potions.effects.get("invisibility").is_some() {
                     continue;
                 }
-                // renderPlayerArm (right arm)
+                // renderPlayerArm
                 let m = to_world
-                    * horizon_client::first_person::player_arm_pose(false, inverse_height, attack);
-                self.first_person_arm(false, m, packed, &mut out);
+                    * horizon_client::first_person::player_arm_pose(left, inverse_height, attack);
+                self.first_person_arm(left, m, packed, &mut out);
                 continue;
             };
             if let Some(id) = maps::map_id(&stack) {
@@ -11001,6 +11046,9 @@ impl Game<'_> {
             self.all_sections_changed();
         }
         self.audio.master = self.settings.master_volume;
+        if self.settings.sound_device != self.audio.device() {
+            let _ = self.audio.set_device(&self.settings.sound_device);
+        }
         horizon_client::hud::GUI_SCALE.store(
             self.settings.gui_scale,
             std::sync::atomic::Ordering::Relaxed,
@@ -11591,7 +11639,10 @@ impl Game<'_> {
         self.draw_carried(batch);
         if tab.inventory {
             if Self::creative_trash_hovered(batch, self.cursor) {
-                self.tooltip(batch, "Destroy Item", self.cursor.0, self.cursor.1);
+                // `CreativeModeInventoryScreen`: the destroy slot's tooltip is
+                // `inventory.binSlot`, not an English literal.
+                let destroy = self.translate("inventory.binSlot", "Destroy Item");
+                self.tooltip(batch, &destroy, self.cursor.0, self.cursor.1);
             } else if self.carried.is_none()
                 && let Some(slot) = self.slot_at(batch, self.cursor.0, self.cursor.1)
                 && let Some(stack) = self.slot_view(slot)
@@ -11826,7 +11877,59 @@ impl Game<'_> {
         }
         Ok(())
     }
+    /// `GameRenderer.tryTakeScreenshotIfNeeded`: while a local world without a
+    /// saved icon is on the screen, grab the rendered frame once a second until
+    /// the save has one. The Select World list shows it as the world's preview.
+    fn tick_world_icon(&mut self) {
+        let Some(icon) = self.world_icon.as_ref() else {
+            return;
+        };
+        if icon
+            .last_attempt
+            .is_some_and(|at| at.elapsed() < Duration::from_secs(1))
+        {
+            return;
+        }
+        if icon.path.is_file() {
+            // tryTakeScreenshotIfNeeded's hasWorldScreenshot: it has one, stop asking.
+            self.world_icon = None;
+            return;
+        }
+        // takeAutoScreenshot only saves with every loaded section rendered, or
+        // the icon would picture the holes the streamer has not filled yet.
+        if self.streaming.pending() != 0
+            || !self.pending_uploads.is_empty()
+            || self.remote_backlog() != 0
+        {
+            return;
+        }
+        let Some(renderer) = self.renderer.as_mut() else {
+            return;
+        };
+        // countRenderedSections() > 10: a client that joined its server
+        // thread has nothing pending before the first chunks arrive, and the
+        // icon would be only sky.
+        if renderer.drawn_sections <= 10 {
+            return;
+        }
+        if renderer.screenshot.is_some() {
+            // F2's or an agent's screenshot owns the frame this time; ours
+            // comes around again with the next attempt.
+            return;
+        }
+        let path = icon.path.clone();
+        if let Some(icon) = self.world_icon.as_mut() {
+            icon.last_attempt = Some(Instant::now());
+        }
+        renderer.screenshot = Some(horizon_client::gfx::ScreenshotRequest {
+            path,
+            size: Some([64, 64]),
+        });
+    }
     fn render(&mut self) -> Result<bool> {
+        if self.renderer.as_mut().is_some_and(|r| r.display_changed()) {
+            self.apply_ui_settings();
+        }
         // Minecraft.doWorldLoad: the LevelLoadingScreen while single player's
         // server starts. Its chunk map and progress are the server's, which
         // the window doesn't see yet: the title alone, over the menu background.
@@ -11919,7 +12022,6 @@ impl Game<'_> {
                 self.pitch,
             ),
         };
-        let (view_yaw, view_pitch) = self.shaken_view(view_yaw, view_pitch);
         self.audio
             .set_listener([camera.x, camera.y, camera.z], view_yaw, view_pitch);
         let block = [
@@ -12258,10 +12360,7 @@ impl Game<'_> {
             dynamic_lights: &self.dynamic_lights,
             lightning: horizon_client::gfx::lightning::Input {
                 bolts: &bolts,
-                uv: [
-                    self.gui.atlas.font.white().u0,
-                    self.gui.atlas.font.white().v0,
-                ],
+                uv: horizon_client::gfx::lightning::white_uv(&self.gui.atlas.font.white()),
             },
             additive: &additive,
             see_through: &see_through,
@@ -12436,9 +12535,6 @@ impl Game<'_> {
             }
             return Ok(());
         }
-        if self.screen == Screen::Mod && self.mod_screen_key(key) {
-            return Ok(());
-        }
         if self.sort_key_press(key) {
             return Ok(());
         }
@@ -12476,7 +12572,6 @@ impl Game<'_> {
                 Screen::CommandBlock => self.close_command_block(),
                 Screen::Chat => self.close_chat(),
                 Screen::Win => self.close_win_screen()?,
-                Screen::Mod => self.close_mod_screen(true),
             },
             KeyCode::Digit1
             | KeyCode::Digit2
@@ -12606,10 +12701,6 @@ impl Game<'_> {
     }
     /// A mouse button while playing (window or control socket).
     fn play_mouse(&mut self, button: MouseButton, pressed: bool) -> Result<()> {
-        // A mod's claimed item takes the use button (capability `input`).
-        if self.mod_use(button, pressed) {
-            return Ok(());
-        }
         if self.sleeping.is_some() {
             return Ok(());
         }
@@ -12677,19 +12768,11 @@ impl Game<'_> {
         }
         Ok(())
     }
-    /// LOD Distance and Far Detail Reduced as chosen: the player's LOD
-    /// Distance when it is on, else a mod's far terrain
-    /// (`render.set-far-terrain`).
+    /// LOD Distance and Far Detail Reduced as the player chose them.
     fn far_terrain_choice(&self) -> (u32, bool) {
         let g = &self.settings.horizon;
         let reduced = g.far_detail == horizon_client::graphics::FarDetail::Reduced;
-        if g.lod_distance > 0 {
-            return (g.lod_distance, reduced);
-        }
-        match self.mod_far_terrain() {
-            Some(f) => (f.distance, reduced || f.reduced),
-            None => (0, reduced),
-        }
+        (g.lod_distance, reduced)
     }
     /// LOD Distance as far terrain uses it (`graphics::lod_distance_capped`).
     fn lod_distance(&self) -> u32 {
@@ -12827,12 +12910,14 @@ impl Game<'_> {
         if let Some(renderer) = self.renderer.as_mut() {
             let g = &self.settings.horizon;
             let budgeted = g.chunk_updates > 0 || g.upload_budget_kib > 0;
+            // The meshes, once copied, are freed by a worker (`Streaming::free`).
             if !budgeted && self.pending_uploads.is_empty() {
                 horizon_client::spans::time("upload", || {
-                    for (key, mesh) in uploads {
-                        renderer.upload(key, &mesh);
+                    for (key, mesh) in &uploads {
+                        renderer.upload(*key, mesh);
                     }
                 });
+                self.streaming.free(uploads);
             } else {
                 // Horizon's chunk-update and upload budgets: the nearest
                 // sections go first, the rest wait for later frames; a newer
@@ -12842,12 +12927,17 @@ impl Game<'_> {
                 let fresh: horizon_client::fast_hash::FxHashSet<(i32, i32, i32)> =
                     uploads.iter().map(|(k, _)| *k).collect();
                 let chunks = &self.world.chunks;
-                pending.retain(|(k, _)| !fresh.contains(k) && chunks.contains_key(&(k.0, k.2)));
-                pending.extend(
-                    uploads
-                        .into_iter()
-                        .filter(|(k, _)| chunks.contains_key(&(k.0, k.2))),
-                );
+                let loaded = |k: &(i32, i32, i32)| chunks.contains_key(&(k.0, k.2));
+                let mut spent: Vec<_> = pending
+                    .extract_if(.., |(k, _)| fresh.contains(k) || !loaded(k))
+                    .collect();
+                for upload in uploads {
+                    if loaded(&upload.0) {
+                        pending.push(upload);
+                    } else {
+                        spent.push(upload);
+                    }
+                }
                 let centre = self.streaming.center;
                 let far = |k: &(i32, i32, i32)| (k.0 - centre.0).pow(2) + (k.2 - centre.1).pow(2);
                 pending.sort_unstable_by_key(|(k, _)| std::cmp::Reverse(far(k)));
@@ -12871,9 +12961,11 @@ impl Game<'_> {
                     }
                     let (key, mesh) = pending.pop().expect("checked above");
                     renderer.upload(key, &mesh);
+                    spent.push((key, mesh));
                     count += 1;
                     bytes += size;
                 }
+                self.streaming.free(spent);
             }
             renderer.remove_columns(unloaded.iter().map(|c| (c.x, c.z)));
             if let (Some(lod), Some(player)) = (&mut self.lod, &self.player) {
@@ -12977,8 +13069,16 @@ impl ApplicationHandler for Game<'_> {
                 self.physical_keys.remove(&key);
             }
         }
+        if let WindowEvent::MouseInput { state, button, .. } = &event {
+            if *state == ElementState::Pressed {
+                self.physical_buttons.insert(*button);
+            } else {
+                self.physical_buttons.remove(button);
+            }
+        }
         if let WindowEvent::Focused(false) = &event {
             self.physical_keys.clear();
+            self.physical_buttons.clear();
         }
         if let WindowEvent::ModifiersChanged(m) = &event {
             self.modifiers = m.state();
@@ -13181,7 +13281,6 @@ impl ApplicationHandler for Game<'_> {
                         && self.sleeping.is_none()
                         && self.player.is_some()
                         && !self.native_wheel_event(d)
-                        && !self.mod_wheel(d)
                         && let Some((wheel, (_, vertical_steps))) =
                             self.mouse
                                 .on_scroll(raw_x, raw_y, discrete, wheel_sensitivity)
@@ -13207,18 +13306,23 @@ impl ApplicationHandler for Game<'_> {
                     if self.screen == Screen::Chat && d != 0.0 {
                         self.chat_scroll(d);
                     }
+                    if self.screen == Screen::CommandBlock && d != 0.0 {
+                        self.command_block_scroll(d);
+                    }
                     if self.screen == Screen::Options && d != 0.0 {
                         self.options_scroll(d);
                     }
-                    if self.screen == Screen::Mod && d != 0.0 {
-                        self.mod_screen_scroll(d);
-                    }
-                    if self.screen == Screen::Creative && d != 0.0 {
+                    // AbstractContainerScreen.mouseScrolled: a bundle under the
+                    // cursor takes the wheel before the screen's own scrolling.
+                    let bundle = bundles::takes_bundle_wheel(self.screen)
+                        && d != 0.0
+                        && self.bundle_scroll(scaled(raw_x), scaled(raw_y));
+                    if self.screen == Screen::Creative && d != 0.0 && !bundle {
                         self.creative_screen.wheel(f64::from(d), &self.pack.names);
                     }
                     if self.screen == Screen::Inventory
                         && d != 0.0
-                        && !self.bundle_scroll(scaled(raw_x), scaled(raw_y))
+                        && !bundle
                         && !self.tweak_scroll(d, self.inventory_target().0)
                     {
                         self.station_scroll(d);
@@ -13390,7 +13494,6 @@ impl ApplicationHandler for Game<'_> {
                                 return Ok(());
                             }
                             self.extras_mouse(button, pressed);
-                            self.mod_mouse_key(button, pressed);
                             if pressed
                                 && self.settings.keys.get("key.smoothCamera")
                                     == horizon_client::keybinds::mouse_name(button)
@@ -13493,7 +13596,6 @@ impl ApplicationHandler for Game<'_> {
                             self.stats_click(size);
                         }
                         Screen::Stats if button == MouseButton::Left => self.stats_release(),
-                        Screen::Mod if pressed => self.mod_screen_click(button),
                         _ => {}
                     }
                 }
@@ -13690,7 +13792,6 @@ impl ApplicationHandler for Game<'_> {
                     let PhysicalKey::Code(key) = event.physical_key else {
                         return Ok(());
                     };
-                    self.mod_key(key, event.state == ElementState::Pressed, event.repeat);
                     self.native_key_event(key, event.state == ElementState::Pressed, event.repeat);
                     // key.smoothCamera toggles the cinematic camera.
                     if self.screen == Screen::Playing
@@ -13795,12 +13896,11 @@ impl ApplicationHandler for Game<'_> {
                         }
                     }
                     self.extras_frame(elapsed);
-                    self.mods_frame(elapsed);
-                    self.poll_moved_extras();
                     self.extras_retry()?;
                     self.apply_mouse_look();
                     self.pad_look(elapsed.as_secs_f32());
                     self.advance_flight();
+                    self.tick_world_icon();
                     let ticked = Instant::now();
                     let rendered = self.render()?;
                     self.apply_cursor_icon();
@@ -13854,6 +13954,7 @@ impl ApplicationHandler for Game<'_> {
                         );
                     }
                     self.clock.end_frame(self.pause);
+                    let mut consumed = false;
                     let finished = self
                         .renderer
                         .as_mut()
@@ -13862,8 +13963,9 @@ impl ApplicationHandler for Game<'_> {
                         && self.ui.screenshot_message.is_some()
                     {
                         self.finish_screenshot(result);
+                        consumed = true;
                     }
-                    if let Some(result) = finished
+                    if let Some(result) = &finished
                         && let Some(reply) = self.pending_screenshot.take()
                     {
                         let _ = reply.send(
@@ -13875,6 +13977,13 @@ impl ApplicationHandler for Game<'_> {
                             }
                             .to_string(),
                         );
+                        consumed = true;
+                    }
+                    // A result nobody asked for was the world icon's
+                    // (`tick_world_icon`): a failure tries again a second
+                    // later, as `tryTakeScreenshotIfNeeded` does.
+                    if !consumed && let Some(Err(error)) = finished {
+                        log::warn!("Horizon: couldn't save the world icon: {error}");
                     }
                     if rendered {
                         self.frame_stats.record(elapsed.as_secs_f32() * 1000.0);
@@ -14137,11 +14246,14 @@ impl<'a> Game<'a> {
             },
             keys: HashSet::new(),
             physical_keys: HashSet::new(),
+            physical_buttons: HashSet::new(),
             left: false,
             right: false,
             cursor: (0.0, 0.0),
             cursor_icon: horizon_client::widgets::Cursor::Arrow,
             captured: false,
+            keyboard_mouse: true,
+            view_at: [0, 0],
             focused: true,
             focus_lost: None,
             modifiers: winit::keyboard::ModifiersState::empty(),
@@ -14393,6 +14505,7 @@ impl<'a> Game<'a> {
             text_selection: Default::default(),
             saved_for_exit: false,
             pending_save: None,
+            world_icon: None,
             forced_hit: None,
             guest_use: None,
             lan_events: Vec::new(),
@@ -15272,7 +15385,6 @@ fn start_game<'a>(
     // Benchmarks measure the game alone.
     if game.options.benchmark.is_none() {
         game.mods.dev = game.options.dev_mods.clone();
-        game.start_moved_extras();
         game.start_mods();
     }
     game.start_agent_control()?;
@@ -15351,6 +15463,7 @@ fn start_game<'a>(
                 &game.options.resources,
             );
             title.last_server = game.settings.file.string("lastServer");
+            title.skip_multiplayer_warning = game.settings.file.bool("skipMultiplayerWarning");
             game.title = Some(title);
         }
     }
@@ -15422,6 +15535,8 @@ struct Loading {
     progress: Progress,
     receiver: Receiver<LoaderMsg>,
     loaded: Option<std::result::Result<Loaded, String>>,
+    /// The loader's `Done` arrived: its channel closing afterwards is expected.
+    delivered: bool,
     handle: Option<JoinHandle<()>>,
     shown: bool,
     menu: startup_menu::StartupMenu,
@@ -15522,6 +15637,12 @@ impl Loading {
         }
     }
     fn about_to_wait(&mut self, event_loop: &ActiveEventLoop) {
+        // The loop may run once more after exit(): keep the first error, the
+        // one that ended loading.
+        if self.error.is_some() {
+            event_loop.exit();
+            return;
+        }
         if horizon_threads::stop_requests() > 0 {
             // No world is open yet: nothing to save.
             event_loop.exit();
@@ -15605,7 +15726,7 @@ impl Loading {
         let audio = if !options.execution_role.is_client() {
             Audio::silent(&options.resources)
         } else {
-            Audio::new(&options.resources)
+            Audio::with_device(&options.resources, &self.settings.sound_device)
         };
         let pack_error = loaded.pack_error.or_else(|| self.pack_error.take());
         // The game borrows its shared resources for the process's lifetime,
@@ -15723,6 +15844,22 @@ impl ApplicationHandler for App {
     }
 }
 
+/// Every launch reads the prepared game files (`horizon-prepare`'s output, whose
+/// manifest is `horizon-resources.json`): without them, say where they were
+/// looked for and how to get them, before a window or a loader starts.
+fn missing_resources(root: &std::path::Path) -> Option<String> {
+    if root.join("horizon-resources.json").is_file() {
+        return None;
+    }
+    let shown = std::path::absolute(root).unwrap_or_else(|_| root.to_path_buf());
+    Some(format!(
+        "Horizon's prepared game files are missing: no horizon-resources.json in {}\n\
+         Start Horizon from the Horizon launcher, which downloads and prepares them, \
+         or prepare them with: horizon-prepare --prepare (or pass --resources <folder>)",
+        shown.display()
+    ))
+}
+
 /// The ordinary launch: load the resources on a worker while the window shows
 /// the loading screen, then swap in the game on the main thread.
 fn run_loading(
@@ -15750,6 +15887,7 @@ fn run_loading(
         progress,
         receiver,
         loaded: None,
+        delivered: false,
         handle: Some(loader),
         shown: false,
         menu,
@@ -15819,6 +15957,9 @@ pub fn run() -> Result<()> {
     let started = Instant::now();
     horizon_client::spans::enable(options.spikes.is_some());
     let vanilla_root = options.resources.clone();
+    if let Some(error) = missing_resources(&vanilla_root) {
+        return Err(error.into());
+    }
     let early_settings = Settings::load(&std::env::current_dir()?.join("options.txt"));
     // "Playing Horizon" on Discord: never for a server; an automated run only talks to a test's fake Discord.
     if options.dedicated.is_none() {
@@ -15860,7 +16001,7 @@ pub fn run() -> Result<()> {
     let audio = if !options.execution_role.is_client() {
         Audio::silent(&options.resources)
     } else {
-        Audio::new(&options.resources)
+        Audio::with_device(&options.resources, &early_settings.sound_device)
     };
     let resources = loaded.resources;
     let game = start_game(
@@ -15922,6 +16063,21 @@ fn reset_world_progress(adv: &mut advancements::AdvState, stats: &mut stats::Sta
 mod startup_cpu_tests {
     use super::*;
 
+    #[test]
+    fn a_folder_without_prepared_files_is_named_before_loading() {
+        let root = std::env::temp_dir().join(format!("horizon-unprepared-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&root);
+        let missing = missing_resources(&root.join(".local/horizon-client/26.3"))
+            .expect("no manifest is reported");
+        assert!(missing.contains("horizon-resources.json"), "{missing}");
+        assert!(missing.contains("horizon-unprepared-"), "{missing}");
+        assert!(missing.contains("launcher"), "{missing}");
+        std::fs::create_dir_all(&root).unwrap();
+        std::fs::write(root.join("horizon-resources.json"), "{}").unwrap();
+        assert_eq!(missing_resources(&root), None);
+        std::fs::remove_dir_all(&root).unwrap();
+    }
+
     #[test]
     fn worker_prepares_owned_models_and_inventory_before_handoff() {
         let root = std::env::temp_dir().join(format!("horizon-startup-cpu-{}", std::process::id()));

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

@@ -424,7 +424,6 @@ impl Game<'_> {
             Screen::DialogWarning => "dialog-warning",
             Screen::CommandBlock => "command-block",
             Screen::Win => "win",
-            Screen::Mod => "mod",
         }
     }
     pub(super) fn inventory_counts(&self) -> BTreeMap<String, i64> {
@@ -611,6 +610,9 @@ impl Game<'_> {
                 json!({ "mode": "multiplayer", "disconnected": reason })
             }
             Mode::Multiplayer(_) => json!({ "mode": "multiplayer" }),
+            Mode::MultiplayerWarning { check } => {
+                json!({ "mode": "multiplayer-warning", "check": check })
+            }
         }
     }
 
@@ -1454,7 +1456,15 @@ 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/block_items.rs

@@ -153,5 +153,6 @@ impl Game<'_> {
             };
         }
         self.world.block_entities.insert(key, entity);
+        self.update_spawner_display(key);
     }
 }

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

@@ -20,13 +20,12 @@ use std::{
 
 /// The tree the chat parses and completes with: a server's, once it has
 /// sent one (ClientPacketListener.commands), else the game's own.
-fn chat_tree<'a>(
-    remote: &'a Option<super::remote::Remote>,
-    mods: &'a super::mods::ModsState,
-) -> &'a horizon_client::command::Dispatcher {
+pub(super) fn chat_tree(
+    remote: &Option<super::remote::Remote>,
+) -> &horizon_client::command::Dispatcher {
     match remote.as_ref().and_then(|r| r.commands.as_ref()) {
-        Some(tree) => mods.remote_dispatcher().unwrap_or(tree),
-        None => mods.dispatcher(),
+        Some(tree) => tree,
+        None => horizon_client::command::vanilla::game_dispatcher(),
     }
 }
 use winit::{
@@ -148,7 +147,7 @@ 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 +155,26 @@ 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 +194,7 @@ 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('\\', "/")
                 ));
             }
@@ -459,7 +478,7 @@ impl Game<'_> {
         let b = HudBatch::new(size);
         let m = Measure(&self.gui.atlas.font);
         let c = Commands {
-            dispatcher: chat_tree(&self.remote, &self.mods),
+            dispatcher: chat_tree(&self.remote),
             registries: &self.ui.registries,
         };
         let mut screen = ChatScreen::new(
@@ -559,13 +578,12 @@ impl Game<'_> {
         }
     }
     /// A line on the window's own chat when the Chat option lets `source`
-    /// through; running mods hear it.
+    /// through.
     fn local_chat_line(&mut self, text: Text, indicator: Option<u32>, source: ChatSource) {
         if !self.ui.chat.shows(source) {
             return;
         }
         let focused = self.screen == Screen::Chat;
-        let heard = self.mods.running().then(|| text.plain());
         self.ui.chat.add(
             &self.gui.atlas,
             text,
@@ -574,16 +592,13 @@ impl Game<'_> {
             self.ticks,
             focused,
         );
-        if let Some(line) = heard {
-            self.mods_chat(&line);
-        }
     }
     /// Keys while the chat screen is open.
     pub(super) fn chat_key(&mut self, event: &KeyEvent) {
         if let Some(shortcut) = self.edit_shortcut(event) {
             let m = Measure(&self.gui.atlas.font);
             let c = Commands {
-                dispatcher: chat_tree(&self.remote, &self.mods),
+                dispatcher: chat_tree(&self.remote),
                 registries: &self.ui.registries,
             };
             if let Some(screen) = self.ui.chat_screen.as_mut() {
@@ -629,7 +644,7 @@ impl Game<'_> {
         };
         let m = Measure(&self.gui.atlas.font);
         let c = Commands {
-            dispatcher: chat_tree(&self.remote, &self.mods),
+            dispatcher: chat_tree(&self.remote),
             registries: &self.ui.registries,
         };
         match screen.key(&m, &c, &self.ui.chat.recent, key, shift, ctrl) {
@@ -651,7 +666,7 @@ 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);
                 }
@@ -669,7 +684,7 @@ impl Game<'_> {
     ) {
         let m = Measure(&self.gui.atlas.font);
         let c = Commands {
-            dispatcher: chat_tree(&self.remote, &self.mods),
+            dispatcher: chat_tree(&self.remote),
             registries: &self.ui.registries,
         };
         if let Some(screen) = self.ui.chat_screen.as_mut() {
@@ -680,7 +695,7 @@ impl Game<'_> {
     pub(super) fn chat_type(&mut self, text: &str) {
         let m = Measure(&self.gui.atlas.font);
         let c = Commands {
-            dispatcher: chat_tree(&self.remote, &self.mods),
+            dispatcher: chat_tree(&self.remote),
             registries: &self.ui.registries,
         };
         if let Some(screen) = self.ui.chat_screen.as_mut() {
@@ -707,8 +722,8 @@ impl Game<'_> {
             return;
         }
         if let Some(command) = message.strip_prefix('/') {
-            // A client mod's command first, then a server mod's, as on a server.
-            if !self.client_mod_command(command) && !self.local_server_mod_command(command) {
+            // A native mod's command first.
+            if !self.client_mod_command(command) {
                 self.run_command(command);
             }
         } else {
@@ -717,7 +732,6 @@ impl Game<'_> {
                 &[self.player_display_name(), Text::literal(message)],
             );
             let focused = self.screen == Screen::Chat;
-            let heard = self.mods.running().then(|| line.plain());
             self.ui.chat.add(
                 &self.gui.atlas,
                 line,
@@ -726,11 +740,7 @@ impl Game<'_> {
                 self.ticks,
                 focused,
             );
-            if let Some(line) = heard {
-                self.mods_chat(&line);
-            }
             self.lan_host_chat(message);
-            self.mod_player_chat(super::server_mods::Who::Local, message);
         }
     }
     pub(super) fn chat_scroll(&mut self, amount: f32) {
@@ -757,7 +767,7 @@ impl Game<'_> {
         });
         let m = Measure(&self.gui.atlas.font);
         let c = Commands {
-            dispatcher: chat_tree(&self.remote, &self.mods),
+            dispatcher: chat_tree(&self.remote),
             registries: &self.ui.registries,
         };
         if self.ui.in_bed_chat && self.sleeping.is_some() {
@@ -902,7 +912,7 @@ impl Game<'_> {
         }
         if self.remote.is_some() {
             self.send_chat(&format!("/{command}"));
-        } else if !self.local_server_mod_command(command) {
+        } else {
             self.run_command(command);
         }
     }
@@ -922,7 +932,7 @@ impl Game<'_> {
         };
         let m = Measure(&self.gui.atlas.font);
         let c = Commands {
-            dispatcher: chat_tree(&self.remote, &self.mods),
+            dispatcher: chat_tree(&self.remote),
             registries: &self.ui.registries,
         };
         screen.resize(&m, &c, batch.width as i32, batch.height as i32);
@@ -1183,7 +1193,10 @@ impl Game<'_> {
             return;
         };
         let path = dir.join(name);
-        renderer.screenshot = Some(path.clone());
+        renderer.screenshot = Some(horizon_client::gfx::ScreenshotRequest {
+            path: path.clone(),
+            size: None,
+        });
         self.ui.screenshot_message = Some(path);
     }
     /// After a frame: report a finished F2 screenshot in chat.

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/command_blocks.rs

@@ -4,18 +4,21 @@
 //! `CommandBlockEditScreen` with what `handleSetCommandBlock` does with it.
 use super::{Game, Screen, commands::execute::Source, lan::LanHost};
 use horizon_client::{
+    chat::{ChatScreen, Commands},
     command_block::{self, CommandBlock, Mode},
     containers::BlockEntity,
     hud::{HudBatch, rgba},
+    screen_draw::Measure,
     text::{self, Text},
     ui::{self, EditBox},
     world::World,
 };
 use horizon_core::position::BlockPos;
-use horizon_protocol::packets::play::{self, Serverbound as S};
+use horizon_protocol::packets::play::{self, Clientbound as C, Serverbound as S};
 use horizon_world::{
     chunk::BlockState,
     level::flags,
+    nbt::Tag,
     registry::{BlockRegistry, BlockStateId},
 };
 use winit::{
@@ -28,7 +31,10 @@ type Pos = (i32, i32, i32);
 /// The open `CommandBlockEditScreen`.
 pub(super) struct CommandBlockScreen {
     pos: Pos,
-    command: EditBox,
+    /// The command box with its `CommandSuggestions`.
+    command: ChatScreen,
+    /// When the command box was focused, for its cursor's blink.
+    opened: std::time::Instant,
     previous: EditBox,
     track_output: bool,
     mode: Mode,
@@ -93,6 +99,9 @@ impl CommandBlockScreen {
             Button::Cancel => tr("gui.cancel"),
         }
     }
+    pub(super) fn pos(&self) -> Pos {
+        self.pos
+    }
     /// `updatePreviousOutput`.
     fn show_previous(&mut self, block: &CommandBlock) {
         let shown = if self.track_output {
@@ -446,10 +455,14 @@ impl Game<'_> {
         let Some(state) = self.block_state_at(pos) else {
             return;
         };
-        let mut command = EditBox::new(0.0, 50.0, 300.0, 20.0);
-        command.max_length = 32500;
-        command.set_value(&block.command);
-        command.focused = true;
+        let (w, h) = self.gui_size();
+        let m = Measure(&self.gui.atlas.font);
+        let c = Commands {
+            dispatcher: super::chat::chat_tree(&self.remote),
+            registries: &self.ui.registries,
+        };
+        let mut command = ChatScreen::command_block(&m, &c, &block.command, w as i32, h as i32);
+        command.auto_suggestions = self.settings.auto_suggestions;
         let mut previous = EditBox::new(0.0, 135.0, 276.0, 20.0);
         previous.max_length = 32500;
         previous.text_color = UNEDITABLE;
@@ -457,6 +470,7 @@ impl Game<'_> {
         let mut screen = CommandBlockScreen {
             pos,
             command,
+            opened: std::time::Instant::now(),
             previous,
             track_output: block.track_output,
             mode: Mode::of_block(&state.name).unwrap_or(Mode::Redstone),
@@ -485,7 +499,14 @@ impl Game<'_> {
         let atlas = &self.gui.atlas;
         let (w, h) = (batch.width, batch.height);
         let mid = (w / 2.0).floor();
-        ui::menu_background(batch, atlas, 0.0, 0.0, w, h, true);
+        // Screen.extractBackground of an isInGameUi screen: the dimmed world,
+        // with no blur and no menu background.
+        batch.fill_gradient(
+            atlas,
+            (0.0, 0.0, w, h),
+            rgba(0x10, 0x10, 0x10, 0xC0),
+            rgba(0x10, 0x10, 0x10, 0xD0),
+        );
         let title = Text::translate("advMode.setCommand", &[]);
         let tw = atlas.font.width_text(&title);
         batch.text_styled(
@@ -499,8 +520,6 @@ impl Game<'_> {
         let grey = rgba(160, 160, 160, 255);
         let label = Text::translate("advMode.command", &[]);
         batch.text_styled(atlas, &label, mid - 149.0, 40.0, grey, true);
-        s.command.x = mid - 150.0;
-        s.command.draw(batch, atlas, None);
         if !s.previous.value.is_empty() {
             let label = Text::translate("advMode.previousOutput", &[]);
             batch.text_styled(atlas, &label, mid - 149.0, 125.0, grey, true);
@@ -511,12 +530,65 @@ impl Game<'_> {
             let hover = ui::hovered(self.cursor, x, y, bw, 20.0);
             ui::button(batch, atlas, x, y, bw, 20.0, &s.label(b), true, hover);
         }
+        // The command box, then its suggestions over the widgets.
+        let m = Measure(&atlas.font);
+        let c = Commands {
+            dispatcher: super::chat::chat_tree(&self.remote),
+            registries: &self.ui.registries,
+        };
+        s.command.resize(&m, &c, w as i32, h as i32);
+        let mouse = (self.cursor.0.floor() as i32, self.cursor.1.floor() as i32);
+        let blink = s.opened.elapsed().as_millis() as u64;
+        let draws = s.command.draw(&m, mouse, blink, 0);
+        horizon_client::screen_draw::paint(batch, atlas, &draws);
+        self.command_block_screen = Some(s);
+    }
+    /// The wheel over the suggestion list (`CommandSuggestions.mouseScrolled`).
+    pub(super) fn command_block_scroll(&mut self, amount: f32) {
+        let mouse = (self.cursor.0.floor() as i32, self.cursor.1.floor() as i32);
+        if let Some(s) = self.command_block_screen.as_mut() {
+            s.command.scroll(mouse, f64::from(amount));
+        }
+    }
+    /// The command box's completion request for an `ask_server` node.
+    pub(super) fn command_block_suggestion_request(&mut self) -> Option<(i32, String)> {
+        self.command_block_screen.as_mut()?.command.take_request()
+    }
+    /// The server's completions for the command box's `ask_server` request.
+    pub(super) fn command_block_server_suggestions(
+        &mut self,
+        id: i32,
+        range: (usize, usize),
+        list: Vec<(String, Option<String>)>,
+    ) {
+        let Some(mut s) = self.command_block_screen.take() else {
+            return;
+        };
+        let m = Measure(&self.gui.atlas.font);
+        let c = Commands {
+            dispatcher: super::chat::chat_tree(&self.remote),
+            registries: &self.ui.registries,
+        };
+        s.command.server_suggestions(&m, &c, id, range, list);
         self.command_block_screen = Some(s);
     }
     pub(super) fn command_block_click(&mut self) {
         let Some(mut s) = self.command_block_screen.take() else {
             return;
         };
+        // CommandSuggestions.mouseClicked first, then the command box.
+        {
+            let m = Measure(&self.gui.atlas.font);
+            let c = Commands {
+                dispatcher: super::chat::chat_tree(&self.remote),
+                registries: &self.ui.registries,
+            };
+            let (x, y) = (f64::from(self.cursor.0), f64::from(self.cursor.1));
+            if s.command.click(&m, &c, x, y) {
+                self.command_block_screen = Some(s);
+                return;
+            }
+        }
         let size = self
             .renderer
             .as_ref()
@@ -552,8 +624,8 @@ impl Game<'_> {
         }
         self.command_block_screen = Some(s);
     }
-    /// `AbstractCommandBlockEditScreen.keyPressed`: Enter is Done, Escape
-    /// cancels, the rest edits the command.
+    /// `AbstractCommandBlockEditScreen.keyPressed`: the suggestions first,
+    /// then Enter is Done, Escape cancels, the rest edits the command.
     pub(super) fn command_block_key(&mut self, event: &KeyEvent) {
         if event.state != ElementState::Pressed {
             return;
@@ -561,27 +633,58 @@ impl Game<'_> {
         let PhysicalKey::Code(key) = event.physical_key else {
             return;
         };
+        let shortcut = self.edit_shortcut(event);
+        self.command_block_key_code(key, shortcut, event.text.as_deref());
+    }
+    /// A key pressed on the command block screen, with the edit shortcut it
+    /// makes and the text it types.
+    pub(super) fn command_block_key_code(
+        &mut self,
+        key: KeyCode,
+        shortcut: Option<horizon_client::clipboard::EditShortcut>,
+        text: Option<&str>,
+    ) {
+        let ctrl = self.keys.contains(&KeyCode::ControlLeft);
+        let shift = self.keys.contains(&KeyCode::ShiftLeft);
+        // Windows' AltGr is Ctrl+Alt, and its characters still type.
+        let types_text = self.types_text();
+        let Some(mut s) = self.command_block_screen.take() else {
+            return;
+        };
+        let m = Measure(&self.gui.atlas.font);
+        let c = Commands {
+            dispatcher: super::chat::chat_tree(&self.remote),
+            registries: &self.ui.registries,
+        };
+        if s.command.suggestions_key(&m, &c, key, shift) {
+            self.command_block_screen = Some(s);
+            return;
+        }
+        let typed = match key {
+            KeyCode::Escape | KeyCode::Enter | KeyCode::NumpadEnter => false,
+            _ => {
+                if let Some(shortcut) = shortcut {
+                    s.command.shortcut(&m, &c, shortcut, &mut self.clipboard);
+                    false
+                } else {
+                    !s.command.field_key(&m, &c, key, shift, ctrl) && types_text
+                }
+            }
+        };
+        self.command_block_screen = Some(s);
+        if typed {
+            self.command_block_type(text.unwrap_or(""));
+        }
         match key {
-            KeyCode::Escape => return self.close_command_block(),
+            KeyCode::Escape => self.close_command_block(),
             KeyCode::Enter | KeyCode::NumpadEnter => {
                 if let Some(s) = self.command_block_screen.take() {
                     self.set_command_block(&s);
                 }
-                return self.close_command_block();
+                self.close_command_block();
             }
             _ => {}
         }
-        let ctrl = self.keys.contains(&KeyCode::ControlLeft);
-        let shift = self.keys.contains(&KeyCode::ShiftLeft);
-        let shortcut = self.edit_shortcut(event);
-        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 {
-            self.command_block_type(event.text.as_deref().unwrap_or(""));
-        }
     }
     /// Characters typed into the command box (`StringUtil.isAllowedChatCharacter`).
     pub(super) fn command_block_type(&mut self, typed: &str) {
@@ -589,11 +692,19 @@ impl Game<'_> {
             .chars()
             .filter(|&c| c != '\u{a7}' && c >= ' ' && c != '\u{7f}')
             .collect();
-        if let Some(s) = self.command_block_screen.as_mut()
-            && !allowed.is_empty()
-        {
-            s.command.insert_text(&allowed);
+        if allowed.is_empty() {
+            return;
         }
+        let Some(mut s) = self.command_block_screen.take() else {
+            return;
+        };
+        let m = Measure(&self.gui.atlas.font);
+        let c = Commands {
+            dispatcher: super::chat::chat_tree(&self.remote),
+            registries: &self.ui.registries,
+        };
+        s.command.type_text(&m, &c, &allowed);
+        self.command_block_screen = Some(s);
     }
     /// The edit screen's Done: a server's client sends the packet, the
     /// window's own world applies it (`handleSetCommandBlock`).
@@ -604,7 +715,7 @@ impl Game<'_> {
         }
         let edit = CommandBlockEdit {
             pos: s.pos,
-            command: s.command.value.clone(),
+            command: s.command.value().to_owned(),
             track_output: s.track_output,
             mode: s.mode,
             conditional: s.conditional,
@@ -653,6 +764,46 @@ impl Game<'_> {
             }
         });
     }
+    /// `ServerPlayer.openCommandBlock`: the command block's data
+    /// (`saveCustomOnly`) goes to the guest whose use opened it, as the
+    /// chunk's update tag leaves it out and the edit screen shows it.
+    pub(super) fn lan_open_command_block(&mut self, host: &mut LanHost, conn: u32, pos: Pos) {
+        if !host
+            .hub
+            .guest(conn)
+            .is_some_and(|g| g.creative() && g.permission >= 2)
+        {
+            return;
+        }
+        let Some(block) = self.command_block(pos) else {
+            return;
+        };
+        let tag = Tag::compound(block.save());
+        let state = self.world.block(pos.0, pos.1, pos.2).0;
+        let Some(kind) = host.hub.encoder.entity_type(state) else {
+            return;
+        };
+        host.hub.send_to(
+            conn,
+            &C::BlockEntityData(play::BlockEntityData {
+                pos: [pos.0, pos.1, pos.2],
+                kind,
+                tag,
+            }),
+        );
+    }
+    /// `ClientPacketListener.handleBlockEntityData`: new data for the command
+    /// block the edit screen shows refills it (`CommandBlockEditScreen.updateGui`).
+    pub(super) fn command_block_data_arrived(&mut self, pos: Pos) {
+        let open = self.screen == Screen::CommandBlock
+            && self
+                .command_block_screen
+                .as_ref()
+                .is_some_and(|s| s.pos == pos);
+        if open {
+            self.open_command_block(pos);
+        }
+    }
     /// What `handleSetCommandBlock` does once the player may edit the block.
     fn apply_command_block(&mut self, s: &CommandBlockEdit) {
         let pos = s.pos;

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

@@ -2069,6 +2069,7 @@ impl Game<'_> {
             return false;
         }
         self.world.block_entities.insert(key, new);
+        self.update_spawner_display(key);
         self.world.modified.insert((pos[0] >> 4, pos[2] >> 4));
         true
     }

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

@@ -317,6 +317,7 @@ impl Game<'_> {
                 if let Some((_, mut new)) = save::decode_block_entity(&tag) {
                     self.take_loot_table(key, &tag, &mut new);
                     self.world.block_entities.insert(key, new);
+                    self.update_spawner_display(key);
                     let state = self.world.block(p[0], p[1], p[2]);
                     // Redraw what shows the block entity (signs, banners).
                     let _ = self.world.set(p[0], p[1], p[2], state);

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

@@ -246,9 +246,9 @@ impl Game<'_> {
                     c.insert("z".into(), Tag::Int(at[2]));
                 }
                 if let Some((_, entity)) = save::decode_block_entity(&tag) {
-                    self.world
-                        .block_entities
-                        .insert((at[0], at[1], at[2]), entity);
+                    let key = (at[0], at[1], at[2]);
+                    self.world.block_entities.insert(key, entity);
+                    self.update_spawner_display(key);
                 }
             }
         }

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

@@ -22,7 +22,7 @@ const HELP: &[&str] = &[
     "tp X Y Z                       teleport the player",
     "hotbar 1-9                     select a hotbar slot",
     "give ITEM [COUNT]              add items to the inventory",
-    "render-distance N              chunks, 2..64",
+    "render-distance N              chunks, 2..128",
     "lod-distance N                 far surface chunks, 0 disables, up to1024",
     "time TICKS                     set the time of day",
     "summon KIND [X Y Z] [baby]     spawn a mob (in front of the player without a position)",
@@ -34,7 +34,7 @@ const HELP: &[&str] = &[
     "chat TEXT                      send a chat line or /command as if typed",
     "type TEXT                      type into the open chat box (key enter tap sends)",
     "chat-log [N]                   the newest N chat messages (default 10)",
-    "options [PAGE]                 open the options (video sound controls keybinds mouse chat accessibility language font packs mods graphics graphics-advanced)",
+    "options [PAGE]                 open the options (video sound controls keybinds mouse chat accessibility language font packs mods graphics graphics-advanced graphics-hdr)",
     "stats [reset]                  frame-time summary since the last reset",
     "bench SECONDS                  reset stats, wait, then reply with the summary",
     "fly X1 Y1 Z1 X2 Y2 Z2 SECONDS [PITCH [raw]]  fly the camera along a line at constant speed, then reply with the frame summary (raw: every frame time too)",
@@ -339,17 +339,17 @@ impl Game<'_> {
                         self.debug_key(key, KeyAction::Release);
                     }
                 }
-                // Mods' keys (capability `input`) see the key as the keyboard
-                // hook does.
+                // Native mods see the key as the keyboard hook does.
                 let action = arg(2)?;
-                self.mod_key(physical, action != "up", action == "repeat");
                 self.native_key_event(physical, action != "up", action == "repeat");
                 if action == "tap" {
-                    self.mod_key(physical, false, false);
                     self.native_key_event(physical, false, false);
                 }
                 // Text screens consume raw presses; releases follow key binds.
-                let typing = matches!(self.screen, Screen::Chat | Screen::Options);
+                let typing = matches!(
+                    self.screen,
+                    Screen::Chat | Screen::Options | Screen::CommandBlock
+                );
                 let key = if typing && arg(2)? != "up" {
                     key
                 } else {
@@ -422,19 +422,15 @@ impl Game<'_> {
                 match arg(2)? {
                     "down" => {
                         self.extras_mouse(button, true);
-                        self.mod_mouse_key(button, true);
                         self.play_mouse(button, true)?
                     }
                     "up" => {
                         self.extras_mouse(button, false);
-                        self.mod_mouse_key(button, false);
                         self.play_mouse(button, false)?
                     }
                     "click" => {
                         self.extras_mouse(button, true);
-                        self.mod_mouse_key(button, true);
                         self.extras_mouse(button, false);
-                        self.mod_mouse_key(button, false);
                         self.play_mouse(button, true)?;
                         self.play_mouse(button, false)?;
                     }
@@ -517,8 +513,9 @@ impl Game<'_> {
             }
             "render-distance" => {
                 let n: i32 = arg(1)?.parse()?;
-                if !(2..=64).contains(&n) {
-                    return Err("render distance must be 2..64".into());
+                let max = horizon_client::options_file::MAX_RENDER_DISTANCE;
+                if !(2..=max).contains(&n) {
+                    return Err(format!("render distance must be 2..{max}").into());
                 }
                 self.settings.render_distance = n;
                 self.apply_settings();
@@ -588,7 +585,10 @@ impl Game<'_> {
                 arg(1)?;
                 // The rest of the line: a path may hold spaces.
                 let path = line.trim_start().strip_prefix("screenshot").unwrap_or("");
-                renderer.screenshot = Some(path.trim().into());
+                renderer.screenshot = Some(horizon_client::gfx::ScreenshotRequest {
+                    path: path.trim().into(),
+                    size: None,
+                });
                 self.pending_screenshot = Some(reply.clone());
                 Ok(None)
             }
@@ -678,6 +678,7 @@ impl Game<'_> {
                     "shader-packs" => Page::ShaderPacks,
                     "graphics" => Page::Graphics,
                     "graphics-advanced" => Page::GraphicsAdvanced,
+                    "graphics-hdr" => Page::GraphicsHdr,
                     "extras" => Page::Extras,
                     "credits" => Page::Credits,
                     "horizon" => Page::Horizon,
@@ -855,6 +856,10 @@ impl Game<'_> {
         if self.screen == Screen::Options {
             return self.options_key(key, None);
         }
+        if self.screen == Screen::CommandBlock {
+            self.command_block_key_code(key, None, None);
+            return Ok(());
+        }
         if self.keys.insert(key) {
             self.key_pressed(key)?;
         }
@@ -886,7 +891,6 @@ impl Game<'_> {
             Screen::DialogWarning => "dialog-warning",
             Screen::CommandBlock => "command-block",
             Screen::Win => "win",
-            Screen::Mod => "mod",
         }
     }
 

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

@@ -18,7 +18,10 @@ const FIREWORK_ROCKET: &str = "minecraft:firework_rocket";
 
 /// `ProjectileWeaponItem.ARROW_ONLY`, for the arrows Horizon shoots.
 fn is_arrow(stack: &ItemStack) -> bool {
-    &*stack.item == "minecraft:arrow"
+    matches!(
+        &*stack.item,
+        "minecraft:arrow" | "minecraft:spectral_arrow" | "minecraft:tipped_arrow"
+    )
 }
 
 /// `Player.getProjectile`: what `weapon` supports in the off hand, then in
@@ -206,10 +209,14 @@ impl Game<'_> {
                 self.launch_angled_rocket(at, shot.velocity, ammo, Some(Who::Player));
             }
             if !rocket {
+                let effect = super::dispenser::tipped_effect(ammo).or_else(|| {
+                    (&*ammo.item == "minecraft:spectral_arrow")
+                        .then_some(("minecraft:glowing", 200))
+                });
                 let kind = ProjectileKind::Arrow {
                     base_damage: 2.0,
                     critical: true,
-                    effect: None,
+                    effect,
                 };
                 let mut arrow = Projectile::new(
                     kind,
@@ -277,5 +284,17 @@ mod tests {
         // The main hand's rocket, with the crossbow in the off hand.
         let hands = [(OFFHAND_SLOT, crossbow.as_ref()), (3, rocket.as_ref())];
         assert_eq!(projectile_slot(CROSSBOW, hands, &inventory), Some(3));
+
+        // Spectral and tipped arrows in off hand or inventory are recognized.
+        let spectral = stack("minecraft:spectral_arrow");
+        let tipped = stack("minecraft:tipped_arrow");
+        inventory[7] = spectral.clone();
+        assert_eq!(slot("minecraft:bow", &None, &inventory), Some(7));
+        assert_eq!(
+            slot("minecraft:bow", &tipped, &inventory),
+            Some(OFFHAND_SLOT)
+        );
+        inventory[7] = None;
+        assert_eq!(slot("minecraft:bow", &None, &inventory), None);
     }
 }

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

@@ -2140,6 +2140,11 @@ pub(super) fn tipped_effect(stack: &ItemStack) -> Option<(&'static str, i32)> {
             def.effects
                 .iter()
                 .find(|(id, _, _)| !horizon_client::brewing::effect(id).is_some_and(|e| e.instant))
-                .map(|(id, duration, _)| (*id, (duration / 8).max(1)))
+                .map(|(id, duration, _)| {
+                    (
+                        horizon_client::brewing::namespaced(id),
+                        (duration / 8).max(1),
+                    )
+                })
         })
 }

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

@@ -2590,54 +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.
@@ -3597,10 +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/extras.rs

@@ -1,7 +1,7 @@
-//! Horizon's extras in the game (`docs/extras.md`); a mod's minimap
-//! (`render.set-minimap`: its tiles, image and HUD) and zoom (`render.set-zoom`) on the camera; clicks
-//! and frame times for mods (`input.clicks-per-second`, `render.frame-stats`).
-//! Each hook does nothing while its extra is off and no mod runs.
+//! Horizon's extras in the game (`docs/extras.md`); a native mod's minimap
+//! (`native_minimap`: its tiles, image and HUD) and zoom (`native_zoom`) on the camera; clicks
+//! and frame times for mods (`native_clicks`, `native_frame_rate`).
+//! Each hook does nothing while its extra is off and no mod uses it.
 use super::{Dim, Game, Screen, native_hooks::NativeMinimap};
 use horizon_client::{
     extras::{Corner, Cps, FpsCounter, fov_target},
@@ -124,7 +124,7 @@ impl Game<'_> {
         }
         Ok(())
     }
-    /// The minimap a mod shows (`render.set-minimap`): its corner, its side
+    /// The minimap a mod shows (`native_minimap`): its corner, its side
     /// in GUI pixels and its view of the player.
     fn minimap_shown(&self) -> Option<(Corner, f32, View)> {
         let p = self.player.as_ref()?;
@@ -142,20 +142,9 @@ impl Game<'_> {
         };
         Some((m.corner, m.size, view))
     }
-    /// The minimap shown: a native mod's (`native_minimap`), else a
-    /// WebAssembly mod's.
+    /// The minimap shown: a native mod's (`native_minimap`).
     fn minimap_wanted(&self) -> Option<NativeMinimap> {
-        if let Some(m) = self.native_minimap_now() {
-            return Some(m);
-        }
-        let m = self.mod_minimap()?;
-        Some(NativeMinimap {
-            corner: m.corner,
-            size: m.size,
-            blocks_per_pixel: m.blocks_per_pixel,
-            rotate: m.rotate,
-            round: m.round,
-        })
+        self.native_minimap_now()
     }
     /// Refresh the minimap's tiles within the frame budget, recompose its
     /// image when the view or a tile changed, and queue the upload.
@@ -209,13 +198,10 @@ impl Game<'_> {
             rgba: self.extras.minimap.image.clone(),
         });
     }
-    /// A mod's zoom in effect (`render.set-zoom`): (factor, smooth, turning
+    /// A mod's zoom in effect (`native_zoom`): (factor, smooth, turning
     /// scale); none is 1.
     fn zoom_now(&self) -> (f32, bool, f64) {
-        if let Some(z) = self.native_zoom_now() {
-            return (z.factor, z.smooth, f64::from(z.turn));
-        }
-        self.mod_zoom().map_or((1.0, true, 1.0), |z| {
+        self.native_zoom_now().map_or((1.0, true, 1.0), |z| {
             (z.factor, z.smooth, f64::from(z.turn))
         })
     }
@@ -240,7 +226,6 @@ impl Game<'_> {
     /// The minimap and mods' corner panels, in the HUD layer (hidden with F1
     /// by the caller). The top left corner gives way to the debug screen.
     pub(super) fn draw_extras(&mut self, batch: &mut HudBatch) {
-        let mod_panels = self.mods.has_panels();
         let map = self.minimap_shown();
         let visible = |corner| !(self.debug && corner == Corner::TopLeft);
         let mut corners = Corners::new(batch.width, batch.height, self.effect_rows_height());
@@ -264,9 +249,6 @@ impl Game<'_> {
             };
             extras_hud::draw_minimap(batch, atlas, &mut corners, &look);
         }
-        if mod_panels {
-            self.draw_mod_panels(batch, &mut corners);
-        }
         self.native_hud(batch, &mut corners);
     }
     /// The height the status effect icons take at the top right

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

@@ -132,6 +132,12 @@ impl Game<'_> {
             "minecraft:glow_item_frame" => true,
             _ => return false,
         };
+        let invisible = stack.extra.as_ref().is_some_and(|extra| {
+            extra.other.iter().any(|(k, v)| {
+                (k == "minecraft:entity_data" || k == "entity_data")
+                    && horizon_client::save::number(v.get("Invisible")).unwrap_or(0) != 0
+            })
+        });
         let pos = std::array::from_fn(|i| hit.pos[i] + hit.face[i]);
         let frame = ItemFrame {
             id: self.next_entity + 1,
@@ -142,7 +148,7 @@ impl Game<'_> {
             rotation: 0,
             drop_chance: 1.0,
             fixed: false,
-            invisible: false,
+            invisible,
             check_interval: 0,
         };
         if !self.frame_survives(&frame) {

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

@@ -7,11 +7,11 @@
 //! into its `IntegratedServer`.
 //!
 //! On by default. `--in-frame` (or `--no-server-thread`, or
-//! `HORIZON_SERVER_THREAD=0`) runs the world in the frame instead, the
-//! escape hatch. LAN guests and dedicated servers use the same code either
-//! way.
+//! `HORIZON_SERVER_THREAD=0`) runs the world in the frame instead. That path
+//! is DEPRECATED: never use it, it gets no fixes and will be removed soon.
+//! LAN guests and dedicated servers use the same code either way.
 use super::{
-    Game, Options, PackResources, Resources, UiResources,
+    Game, Options, PackResources, Resources, UiResources, WorldIcon,
     execution_role::ExecutionRole,
     lan::{LanSettings, Owner},
     world_loading::WorldRequest,
@@ -177,6 +177,8 @@ pub(super) struct Starting {
     handle: Integrated,
     ready: Receiver<Ready>,
     player: String,
+    /// The save's folder in `saves/`, for the world icon once joined.
+    folder: String,
 }
 
 /// The world to open and the player who owns it.
@@ -287,6 +289,7 @@ impl Game<'_> {
             handle,
             ready,
             player,
+            folder: folder.to_owned(),
         });
         // Harnesses, control scripts and runs without a window go on with the world open.
         if self.window.is_none() || super::synchronous_startup(&self.options) {
@@ -318,13 +321,25 @@ impl Game<'_> {
             }
         };
         let Some(Starting {
-            mut handle, player, ..
+            mut handle,
+            player,
+            folder,
+            ..
         }) = self.integrated_starting.take()
         else {
             return Ok(());
         };
         handle.world_name = world_name;
         self.connect_local(pipe, &player)?;
+        // IntegratedServer.getWorldScreenshotFile: the client grabs the frame
+        // the Select World list shows, and needs the save folder for it.
+        self.world_icon = Some(WorldIcon {
+            path: std::env::current_dir()?
+                .join("saves")
+                .join(&folder)
+                .join("icon.png"),
+            last_attempt: None,
+        });
         self.integrated = Some(handle);
         Ok(())
     }

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

@@ -1608,9 +1608,7 @@ impl Game<'_> {
                     event @ (HostEvent::Chat { .. } | HostEvent::Warn(_) | HostEvent::Error(_)) => {
                         self.lan_log_event(event);
                     }
-                    HostEvent::PlayerChat { sender, text } => {
-                        self.mod_player_chat(super::server_mods::Who::Uuid(sender), &text);
-                    }
+                    HostEvent::PlayerChat { .. } => {}
                     HostEvent::Joined(conn) => {
                         self.lan_guest_joined(&mut host, conn, state.as_ref(), entities, spawn);
                         if self.options.dedicated.is_some()

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

@@ -626,7 +626,9 @@ impl Game<'_> {
             }) => Some(key),
             _ => None,
         };
-        self.command_block_screen = host_command_block;
+        // A command block the guest's use opened (Player.openCommandBlock).
+        let guest_command_block =
+            std::mem::replace(&mut self.command_block_screen, host_command_block).map(|s| s.pos());
         // A mount inventory the guest's action opened (shift + use, or the
         // inventory key while riding).
         let guest_mount = std::mem::replace(&mut self.mount_menu, host_mount_menu).opened_mob();
@@ -675,9 +677,7 @@ 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);
@@ -779,6 +779,9 @@ impl Game<'_> {
         if let Some(key) = guest_lectern {
             self.lan_open_lectern(host, conn, key);
         }
+        if let Some(pos) = guest_command_block {
+            self.lan_open_command_block(host, conn, pos);
+        }
         if let Some(pos) = opened_table {
             self.lan_open_crafting(host, conn, pos);
         }
@@ -892,6 +895,12 @@ impl Game<'_> {
         else {
             return false;
         };
+        // The block entity's createMenu: a shulker box opens a ShulkerBoxMenu
+        // (not a 9x3 ChestMenu), whose slots refuse shulker boxes.
+        let menu = match slots {
+            Slots::Block(_) => horizon_client::containers::block_menu_type(name).unwrap_or(menu),
+            _ => menu,
+        };
         // ServerPlayer.openMenu closes the menu that was open.
         self.guest_container_closed(host, conn);
         self.lan_station_closed(host, conn, None);
@@ -1892,10 +1901,6 @@ impl Game<'_> {
             );
             return;
         }
-        // A server mod's command, for every player whatever their level.
-        if self.guest_server_mod_command(host, conn, command.trim_start_matches('/')) {
-            return;
-        }
         // An integrated server runs every player's commands at their own
         // permission level (`CommandSourceStack.permissions`); a LAN world
         // follows its Allow Commands, and a dedicated server leaves it to

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

@@ -154,8 +154,15 @@ impl Game<'_> {
             );
             e.head_yaw = a.yaw;
             e.velocity = [a.velocity.x, a.velocity.y, a.velocity.z];
+            let mut flags = 0i8;
             if a.fire_ticks > 0 {
-                e.meta.push((0, serializer::BYTE, Value::Byte(1)));
+                flags |= 1;
+            }
+            if a.invisible {
+                flags |= 0x20;
+            }
+            if flags != 0 {
+                e.meta.push((0, serializer::BYTE, Value::Byte(flags)));
             }
             // LivingEntity.DATA_HEALTH_ID: 1 until the stand's max health is set.
             e.meta.push((9, serializer::FLOAT, Value::Float(a.health)));
@@ -222,6 +229,9 @@ impl Game<'_> {
                 _ => 0.0,
             };
             e.data = i32::from(f.facing);
+            if f.invisible {
+                e.meta.push((0, serializer::BYTE, Value::Byte(0x20)));
+            }
             // HangingEntity.DATA_DIRECTION, south by default.
             if f.facing != 3 {
                 e.meta

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/levels.rs

@@ -112,17 +112,6 @@ pub(super) struct Levels {
 }
 
 impl Levels {
-    /// The chunks of each level not in place (capability `world` lends
-    /// them to server mods for a call).
-    #[cfg_attr(not(feature = "mods"), allow(dead_code))]
-    pub(super) fn parked_chunks(
-        &mut self,
-    ) -> impl Iterator<Item = (Dim, &mut horizon_client::chunk_map::ChunkMap)> {
-        self.parked
-            .iter_mut()
-            .map(|(d, p)| (*d, &mut p.world.chunks))
-    }
-
     /// The level not in place, in `dim`.
     pub(super) fn parked_mut(&mut self, dim: Dim) -> Option<&mut Parked> {
         self.parked.get_mut(&dim)
@@ -359,8 +348,6 @@ impl Game<'_> {
             };
             self.update_dedicated_streaming();
             self.update_world();
-            // What server mods set in this level since its last tick.
-            self.apply_mod_block_writes();
             result = if paused {
                 self.tick_lan(true);
                 Ok(())

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

@@ -1,212 +0,0 @@
-//! Capability `input` (docs/mods.md): the use button on items a mod claims,
-//! the mod's own keys and the mouse wheel; and `render`'s zoom. With no mod
-//! claiming items, keys or the wheel, each hook here returns after one
-//! check.
-use super::Game;
-use winit::{event::MouseButton, keyboard::KeyCode};
-#[cfg(feature = "mods")]
-use {super::Screen, horizon_mods::HeldItem};
-
-/// A claimed item's use while the button is down.
-#[cfg(feature = "mods")]
-pub(super) struct ModUse {
-    item: HeldItem,
-    /// `Game::ticks` when it started.
-    since: u64,
-}
-
-#[cfg(not(feature = "mods"))]
-impl Game<'_> {
-    pub(super) fn mod_use(&mut self, _button: MouseButton, _pressed: bool) -> bool {
-        false
-    }
-    pub(super) fn mod_key(&mut self, _key: KeyCode, _pressed: bool, _repeat: bool) {}
-    pub(super) fn mod_mouse_key(&mut self, _button: MouseButton, _pressed: bool) {}
-    pub(super) fn mod_wheel(&mut self, _steps: f32) -> bool {
-        false
-    }
-    pub(super) fn mod_zoom(&self) -> Option<ModZoom> {
-        None
-    }
-    pub(super) fn mod_minimap(&self) -> Option<ModMinimap> {
-        None
-    }
-    pub(super) fn mod_far_terrain(&self) -> Option<ModFarTerrain> {
-        None
-    }
-}
-
-/// A mod's zoom (`render.set-zoom`), clamped by the runtime.
-#[derive(Clone, Copy)]
-pub(super) struct ModZoom {
-    pub(super) factor: f32,
-    pub(super) smooth: bool,
-    pub(super) turn: f32,
-}
-
-/// A mod's minimap (`render.set-minimap`), clamped by the runtime.
-#[derive(Clone, Copy)]
-pub(super) struct ModMinimap {
-    pub(super) corner: horizon_client::extras::Corner,
-    pub(super) size: f32,
-    pub(super) blocks_per_pixel: f32,
-    pub(super) rotate: bool,
-    pub(super) round: bool,
-}
-
-/// A mod's far terrain (`render.set-far-terrain`), clamped by the runtime.
-#[derive(Clone, Copy)]
-pub(super) struct ModFarTerrain {
-    pub(super) distance: u32,
-    pub(super) reduced: bool,
-}
-
-#[cfg(feature = "mods")]
-impl Game<'_> {
-    /// The main hand's stack as `input` shows it; none when it is empty.
-    pub(super) fn mod_held(&self) -> Option<HeldItem> {
-        let stack = self.inventory.get(self.selected)?.as_ref()?;
-        Some(HeldItem {
-            id: stack.item.to_string(),
-            count: stack.count,
-            slot: self.selected as u32,
-        })
-    }
-    /// The use button while playing: true when a mod claimed the held item,
-    /// so the game does nothing else with it (no placing, eating, swing).
-    pub(super) fn mod_use(&mut self, button: MouseButton, pressed: bool) -> bool {
-        if button != MouseButton::Right || !self.mods.mods.claims_any() {
-            return false;
-        }
-        if !pressed {
-            return self.stop_mod_use();
-        }
-        let Some(item) = self.mod_held().filter(|h| self.mods.mods.claims(&h.id)) else {
-            return false;
-        };
-        self.mods.mods.use_start(&item);
-        self.mods.using = Some(ModUse {
-            item,
-            since: self.ticks,
-        });
-        true
-    }
-    /// Ends a claimed use: the button came up, the player switched slots,
-    /// or a screen opened. False when none was going.
-    pub(super) fn stop_mod_use(&mut self) -> bool {
-        let Some(u) = self.mods.using.take() else {
-            return false;
-        };
-        let ticks = self.ticks.saturating_sub(u.since).min(u64::from(u32::MAX)) as u32;
-        self.mods.mods.use_stop(&u.item, ticks);
-        true
-    }
-    /// Once a tick: a claimed use stops when its item leaves the hand or a
-    /// screen opens, as vanilla's `releaseUsingItem`.
-    pub(super) fn tick_mod_use(&mut self) {
-        let Some(u) = &self.mods.using else {
-            return;
-        };
-        let still = self
-            .mod_held()
-            .is_some_and(|h| h.id == u.item.id && h.slot == u.item.slot);
-        if !still || self.screen != Screen::Playing {
-            self.stop_mod_use();
-        }
-    }
-    /// A key went down or up: a mod's registered key while playing (no
-    /// screen) is its `key-down` / `key-up`. Vanilla's mapping on the same
-    /// key still runs.
-    pub(super) fn mod_key(&mut self, key: KeyCode, pressed: bool, repeat: bool) {
-        if repeat || !self.mods.mods.has_keys() {
-            return;
-        }
-        // Over an item on a container screen, the mods' keys are `browser`
-        // events (a recipe viewer's R and U).
-        if pressed
-            && self.screen == Screen::Inventory
-            && self.title.is_none()
-            && !self.mod_browser_typing()
-            && let Some(name) = horizon_client::keybinds::key_name(key)
-            && let Some(stack) = self.mod_browser_pointed()
-        {
-            let stack = super::mod_panel::browser_stack(stack);
-            self.mods.mods.browser_key(name, &stack);
-            return;
-        }
-        if pressed && (self.screen != Screen::Playing || self.title.is_some()) {
-            return;
-        }
-        if let Some(name) = horizon_client::keybinds::key_name(key) {
-            self.mods.mods.key(name, pressed);
-        }
-    }
-    /// A mouse button while playing: a mod's key bound to it
-    /// (`key.mouse.4`...), as `mod_key`.
-    pub(super) fn mod_mouse_key(&mut self, button: MouseButton, pressed: bool) {
-        if self.mods.mods.has_keys() {
-            let name = horizon_client::keybinds::mouse_name(button);
-            self.mods.mods.key(&name, pressed);
-        }
-    }
-    /// Wheel steps while playing: true when a mod holds the wheel, so the
-    /// hotbar doesn't move.
-    pub(super) fn mod_wheel(&mut self, steps: f32) -> bool {
-        self.mods.mods.wheel(steps)
-    }
-    /// Playing, with nothing over the world: mods' keys and zoom apply.
-    fn mod_playing(&self) -> bool {
-        self.screen == Screen::Playing
-            && self.title.is_none()
-            && self.sign_edit.is_none()
-            && self.book.is_none()
-    }
-    /// Once a frame, before the mods run: a screen that opened lets their
-    /// held keys up.
-    pub(super) fn mod_input_frame(&mut self) {
-        let playing = self.mod_playing();
-        if self.mods.playing && !playing {
-            self.mods.mods.release_keys();
-        }
-        self.mods.playing = playing;
-    }
-    /// The strongest zoom a mod asks for, while playing; the spyglass's
-    /// own view wins.
-    pub(super) fn mod_zoom(&self) -> Option<ModZoom> {
-        if !self.mod_playing() || self.scoping() {
-            return None;
-        }
-        let z = self.mods.mods.zoom()?;
-        Some(ModZoom {
-            factor: z.factor,
-            smooth: z.smooth,
-            turn: z.turn,
-        })
-    }
-    /// The minimap the first mod showing one asks for.
-    pub(super) fn mod_minimap(&self) -> Option<ModMinimap> {
-        use horizon_client::extras::Corner;
-        use horizon_mods::RenderCorner;
-        let m = self.mods.mods.minimap()?;
-        Some(ModMinimap {
-            corner: match m.corner {
-                RenderCorner::TopLeft => Corner::TopLeft,
-                RenderCorner::TopRight => Corner::TopRight,
-                RenderCorner::BottomLeft => Corner::BottomLeft,
-                RenderCorner::BottomRight => Corner::BottomRight,
-            },
-            size: m.size,
-            blocks_per_pixel: m.blocks_per_pixel,
-            rotate: m.rotate,
-            round: m.round,
-        })
-    }
-    /// The far terrain the first mod drawing one asks for.
-    pub(super) fn mod_far_terrain(&self) -> Option<ModFarTerrain> {
-        let f = self.mods.mods.far_terrain()?;
-        Some(ModFarTerrain {
-            distance: f.distance,
-            reduced: f.reduced,
-        })
-    }
-}

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

@@ -1,114 +0,0 @@
-//! Capability `ui`'s item panel of a WebAssembly mod (WIT `interface
-//! browser`, docs/mods.md): its items and recipe page as the native panel's
-//! (`native_panel.rs`), and the panel's events back in the runtime's types.
-use super::{
-    Game,
-    native_hooks::{
-        NativePanelEvent as BrowserEvent, NativeRecipeLayout, NativeRecipeView,
-        NativeStack as BrowserStack,
-    },
-    native_panel::{Owner, Shown},
-    native_panel_recipes::RecipePage,
-};
-use horizon_mods as m;
-
-/// A WebAssembly mod's panel, converted once per `set-items` or
-/// `set-recipes`.
-impl Game<'_> {
-    pub(super) fn panel_wasm_sync(&mut self) {
-        let Some((index, version, items)) = self.mods.mods.browser_items() else {
-            self.panel.wasm = None;
-            return;
-        };
-        let owner = Owner::Wasm(index);
-        let wasm = self.panel.wasm.as_ref();
-        if wasm.is_some_and(|s| s.owner == owner && s.version == version) {
-            return;
-        }
-        let items = items.iter().map(stack).collect();
-        let recipes = self.mods.mods.browser_recipes(index).map(page);
-        self.panel.wasm = Some(Shown {
-            owner,
-            version,
-            items,
-            recipes,
-        });
-    }
-}
-
-pub(super) fn stack(s: &m::BrowserStack) -> BrowserStack {
-    BrowserStack {
-        item: s.item.clone(),
-        count: s.count,
-        components: s.components.clone(),
-    }
-}
-/// A native stack as the runtime's (`browser_key`).
-pub(super) fn browser_stack(s: BrowserStack) -> m::BrowserStack {
-    m::BrowserStack {
-        item: s.item,
-        count: s.count,
-        components: s.components,
-    }
-}
-fn layout(l: m::BrowserLayout) -> NativeRecipeLayout {
-    match l {
-        m::BrowserLayout::Grid => NativeRecipeLayout::Grid,
-        m::BrowserLayout::Cooking => NativeRecipeLayout::Cooking,
-        m::BrowserLayout::Single => NativeRecipeLayout::Single,
-        m::BrowserLayout::Smithing => NativeRecipeLayout::Smithing,
-        m::BrowserLayout::Brewing => NativeRecipeLayout::Brewing,
-    }
-}
-fn stacks(list: &[m::BrowserStack]) -> Vec<BrowserStack> {
-    list.iter().map(stack).collect()
-}
-pub(super) fn page(p: &m::RecipePage) -> RecipePage {
-    RecipePage {
-        title: p.title.clone(),
-        tabs: stacks(&p.tabs),
-        tab: p.tab,
-        recipes: p
-            .recipes
-            .iter()
-            .map(|r| NativeRecipeView {
-                layout: layout(r.layout),
-                width: r.width,
-                height: r.height,
-                slots: r.slots.iter().map(|s| stacks(s)).collect(),
-                results: stacks(&r.results),
-                note: r.note.clone(),
-                action: r.action,
-            })
-            .collect(),
-    }
-}
-pub(super) fn event(e: BrowserEvent) -> m::BrowserEvent {
-    match e {
-        BrowserEvent::Clicked { index, right } => {
-            m::BrowserEvent::Clicked(m::BrowserClick { index, right })
-        }
-        BrowserEvent::Search(text) => m::BrowserEvent::Search(text),
-        // Not sent to WebAssembly mods: they hear their own keys
-        // (`browser_key`).
-        BrowserEvent::Key { key, stack } => m::BrowserEvent::Key(m::BrowserItemKey {
-            key,
-            stack: browser_stack(stack),
-        }),
-        BrowserEvent::SlotClicked {
-            recipe,
-            slot,
-            stack,
-            right,
-        } => m::BrowserEvent::SlotClicked(m::BrowserSlotClick {
-            recipe,
-            slot,
-            stack: browser_stack(stack),
-            right,
-        }),
-        BrowserEvent::Action(i) => m::BrowserEvent::Action(i),
-        BrowserEvent::Page(i) => m::BrowserEvent::Page(i),
-        BrowserEvent::Back => m::BrowserEvent::Back,
-        BrowserEvent::Tab(i) => m::BrowserEvent::Tab(i),
-    }
-}

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

@@ -1,194 +0,0 @@
-//! Capability `render` (docs/mods.md): the shapes mods keep on the HUD,
-//! drawn by the game's own HUD renderer, and their camera shakes. Mods
-//! never supply shader code. With no mod drawing, each hook here returns
-//! after one check.
-use super::Game;
-use horizon_client::hud::HudBatch;
-#[cfg(feature = "mods")]
-use {
-    horizon_client::{hud::rgba, items::ItemStack, text::Text, ui},
-    horizon_mods::Shape,
-    std::time::Instant,
-};
-
-/// The camera's jolts from `render.shake`, while any is fading.
-#[cfg(feature = "mods")]
-#[derive(Default)]
-pub(super) struct Shake {
-    jolts: Vec<Jolt>,
-}
-
-#[cfg(feature = "mods")]
-struct Jolt {
-    start: Instant,
-    strength: f32,
-    seconds: f32,
-}
-
-/// The HUD batch's colour (ABGR) from a mod's 0xAARRGGBB.
-#[cfg(feature = "mods")]
-fn argb(color: u32) -> u32 {
-    let [a, r, g, b] = color.to_be_bytes();
-    rgba(r, g, b, a)
-}
-
-/// The view's turn at full strength, in degrees: yaw, then pitch.
-#[cfg(feature = "mods")]
-const SHAKE_DEGREES: (f32, f32) = (3.0, 2.0);
-
-#[cfg(feature = "mods")]
-impl Shake {
-    pub(super) fn add(&mut self, strength: f32, seconds: f32) {
-        self.jolts.push(Jolt {
-            start: Instant::now(),
-            strength,
-            seconds,
-        });
-    }
-    /// How far the view turns now (yaw, pitch degrees), `scale` being the
-    /// player's Distortion Effects; fades jolts out and forgets ended ones.
-    fn offset(&mut self, now: Instant, scale: f32) -> (f32, f32) {
-        self.jolts
-            .retain(|j| now.duration_since(j.start).as_secs_f32() < j.seconds);
-        let mut strength = 0.0;
-        for j in &self.jolts {
-            let left = 1.0 - now.duration_since(j.start).as_secs_f32() / j.seconds;
-            strength += j.strength * left * left;
-        }
-        let strength = strength.min(1.0) * scale.clamp(0.0, 1.0);
-        if strength <= 0.0 {
-            return (0.0, 0.0);
-        }
-        // Smooth noise: sines at unrelated rates, so it never repeats visibly.
-        let t = self
-            .jolts
-            .first()
-            .map_or(0.0, |j| now.duration_since(j.start).as_secs_f32());
-        let wave = |a: f32, b: f32, c: f32| {
-            ((t * a).sin() * 0.5 + (t * b).sin() * 0.3 + (t * c).sin() * 0.2).clamp(-1.0, 1.0)
-        };
-        (
-            strength * SHAKE_DEGREES.0 * wave(23.0, 37.3, 51.7),
-            strength * SHAKE_DEGREES.1 * wave(29.1, 43.9, 61.3),
-        )
-    }
-}
-
-#[cfg(not(feature = "mods"))]
-impl Game<'_> {
-    pub(super) fn draw_mod_shapes(&self, _batch: &mut HudBatch) {}
-    pub(super) fn shaken_view(&mut self, yaw: f32, pitch: f32) -> (f32, f32) {
-        (yaw, pitch)
-    }
-}
-
-#[cfg(feature = "mods")]
-impl Game<'_> {
-    /// The running mods' HUD shapes, in order, over the HUD.
-    pub(super) fn draw_mod_shapes(&self, batch: &mut HudBatch) {
-        for shape in self.mods.mods.hud_shapes() {
-            self.draw_shapes(batch, std::slice::from_ref(shape), (0.0, 0.0));
-        }
-    }
-    /// Shapes with their GUI coordinates moved by `(ox, oy)`.
-    pub(super) fn draw_shapes(&self, batch: &mut HudBatch, shapes: &[Shape], (ox, oy): (f32, f32)) {
-        let atlas = &self.gui.atlas;
-        for shape in shapes {
-            match shape {
-                Shape::Fill(f) => {
-                    let r = f.rect;
-                    batch.fill(atlas, ox + r.x, oy + r.y, r.w, r.h, argb(f.color));
-                }
-                Shape::Quad(q) => {
-                    let (a, b, c, d) = q.corners;
-                    let corners = [a, b, c, d].map(|p| [ox + p.x, oy + p.y]);
-                    batch.fill_quad(atlas, corners, argb(q.color));
-                }
-                Shape::Sprite(s) => {
-                    let r = s.rect;
-                    let name = s.sprite.strip_prefix("minecraft:").unwrap_or(&s.sprite);
-                    let name = format!("gui/sprites/{name}");
-                    // As vanilla's blitSprite: a frame or a button keeps its border.
-                    ui::blit_sprite(
-                        batch,
-                        atlas,
-                        &name,
-                        ox + r.x,
-                        oy + r.y,
-                        r.w,
-                        r.h,
-                        argb(s.color),
-                    );
-                }
-                Shape::Item(i) => {
-                    if self.res.items().get(&i.item).is_none() {
-                        continue;
-                    }
-                    let start = batch.vertices.len();
-                    let stack = ItemStack::new(i.item.as_str(), 1);
-                    let (x, y) = (ox + i.at.x, oy + i.at.y);
-                    self.draw_item_model(batch, &stack, x, y);
-                    batch.scale_since(start, x, y, i.scale, i.scale);
-                }
-                Shape::Text(t) => {
-                    let text = Text::literal(t.text.clone());
-                    let centre = if t.centered {
-                        (HudBatch::text_width(atlas, &t.text) / 2.0).floor()
-                    } else {
-                        0.0
-                    };
-                    let x = ox + t.at.x - centre;
-                    batch.text_styled(
-                        atlas,
-                        &text,
-                        x,
-                        oy + t.at.y,
-                        argb(t.color | 0xFF00_0000),
-                        t.shadow,
-                    );
-                }
-            }
-        }
-    }
-    /// The view's yaw and pitch after the mods' camera shakes; unchanged
-    /// while none is fading.
-    pub(super) fn shaken_view(&mut self, yaw: f32, pitch: f32) -> (f32, f32) {
-        if self.mods.shake.jolts.is_empty() {
-            return (yaw, pitch);
-        }
-        let scale = self.settings.file.double("screenEffectScale") as f32;
-        let (dy, dp) = self.mods.shake.offset(Instant::now(), scale);
-        (yaw + dy, (pitch + dp).clamp(-90.0, 90.0))
-    }
-}
-
-#[cfg(all(test, feature = "mods"))]
-mod tests {
-    use super::*;
-    use std::time::Duration;
-
-    #[test]
-    fn a_jolt_fades_out_and_distortion_scales_it() {
-        let mut shake = Shake::default();
-        shake.add(1.0, 2.0);
-        let start = shake.jolts[0].start;
-        let at = |s: f32| start + Duration::from_secs_f32(s);
-        let size = |(y, p): (f32, f32)| y.abs() + p.abs();
-        // Off with Distortion Effects at 0, inside the limits otherwise.
-        assert_eq!(shake.offset(at(0.3), 0.0), (0.0, 0.0));
-        let (y, p) = shake.offset(at(0.3), 1.0);
-        assert!(y.abs() <= SHAKE_DEGREES.0 && p.abs() <= SHAKE_DEGREES.1);
-        // Fading: the largest turn over a window shrinks.
-        let mut peak = |from: f32| {
-            (0..50)
-                .map(|i| size(shake.offset(at(from + i as f32 * 0.002), 1.0)))
-                .fold(0.0, f32::max)
-        };
-        let early = peak(0.1);
-        let late = peak(1.6);
-        assert!(late < early, "{late} !< {early}");
-        // Gone once it ends.
-        assert_eq!(shake.offset(at(2.1), 1.0), (0.0, 0.0));
-        assert!(shake.jolts.is_empty());
-    }
-}

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

@@ -1,122 +0,0 @@
-//! Extras that are official mods now (`horizon_client::moved_extras`): on
-//! the first start after the update, a player who had one on gets the mod
-//! installed from Horizon's registry, turned on, with their settings, and
-//! one line in the chat saying so. The download runs on its own thread; if
-//! it fails (offline), the game tries again at the next start.
-
-#[cfg(not(feature = "mods"))]
-impl super::Game<'_> {
-    pub(super) fn start_moved_extras(&mut self) {}
-    pub(super) fn poll_moved_extras(&mut self) {}
-}
-
-#[cfg(feature = "mods")]
-mod with_mods {
-    use super::super::Game;
-    use horizon_client::{
-        moved_extras::{self, Moved},
-        text::{self, Text},
-    };
-    use std::sync::mpsc::{Receiver, channel};
-
-    type Done = Vec<(&'static Moved, Result<(), String>)>;
-
-    #[derive(Default)]
-    pub(in crate::game) struct MovedState {
-        /// The installs under way.
-        running: Option<Receiver<Done>>,
-        /// Lines for the player, shown once a world is open.
-        notices: Vec<Text>,
-    }
-
-    impl Game<'_> {
-        /// At start: remembers the moved extras that were off, and installs
-        /// the ones that were on, in the background.
-        pub(in crate::game) fn start_moved_extras(&mut self) {
-            let off = moved_extras::nothing_to_do(&self.settings.extras);
-            let pending = moved_extras::pending(&self.settings.extras);
-            if off.is_empty() && pending.is_empty() {
-                return;
-            }
-            if !off.is_empty() {
-                let e = &mut self.settings.extras;
-                e.moved.extend(off.iter().map(|m| m.id.to_owned()));
-                self.settings.save(&Self::options_path());
-            }
-            if pending.is_empty() {
-                return;
-            }
-            let extras = self.settings.extras.clone();
-            let dir = Self::options_path()
-                .parent()
-                .map(std::path::Path::to_path_buf)
-                .unwrap_or_default();
-            let (tx, rx) = channel();
-            self.mods.moved.running = Some(rx);
-            let spawned = std::thread::Builder::new()
-                .name("Moved extras".into())
-                .spawn(move || {
-                    let done = match moved_extras::fetch_index() {
-                        Ok(index) => pending
-                            .into_iter()
-                            .map(|m| (m, moved_extras::install(&index, m, &extras, &dir)))
-                            .collect(),
-                        Err(e) => pending.into_iter().map(|m| (m, Err(e.clone()))).collect(),
-                    };
-                    let _ = tx.send(done);
-                });
-            if spawned.is_err() {
-                self.mods.moved.running = None;
-            }
-        }
-        /// Once a frame: the installs that finished turn their mods on;
-        /// their lines wait for a world.
-        pub(in crate::game) fn poll_moved_extras(&mut self) {
-            if let Some(rx) = &self.mods.moved.running
-                && let Ok(done) = rx.try_recv()
-            {
-                self.mods.moved.running = None;
-                let mut installed = false;
-                for (m, result) in done {
-                    match result {
-                        Ok(()) => {
-                            self.settings.extras.moved.push(m.id.to_owned());
-                            self.settings.mods.enabled.insert(m.id.to_owned());
-                            // The install wrote the key to horizon-mods.txt;
-                            // the settings save below must keep it.
-                            let keys = self.settings.mods.keys.entry(m.id.to_owned()).or_default();
-                            for (name, key) in m.keys(&self.settings.extras) {
-                                keys.entry(name.to_owned()).or_insert(key);
-                            }
-                            self.settings.mods.keys.retain(|_, k| !k.is_empty());
-                            self.mods.moved.notices.push(Text::literal(m.notice()));
-                            installed = true;
-                        }
-                        Err(e) => {
-                            log::warn!("Horizon: {} not installed, next start retries: {e}", m.id);
-                            self.mods.moved.notices.push(
-                                Text::literal(format!(
-                                    "{} moved to the mod browser; it couldn't be installed for you yet, Horizon tries again at the next start",
-                                    m.name
-                                ))
-                                .with_color(text::GRAY),
-                            );
-                        }
-                    }
-                }
-                if installed {
-                    self.settings.save(&Self::options_path());
-                    self.start_mods();
-                }
-            }
-            if !self.mods.moved.notices.is_empty() && self.player.is_some() && self.title.is_none()
-            {
-                for line in std::mem::take(&mut self.mods.moved.notices) {
-                    self.system_message(line);
-                }
-            }
-        }
-    }
-}
-#[cfg(feature = "mods")]
-pub(super) use with_mods::MovedState;

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

@@ -4,7 +4,8 @@
 //! mob is under the crosshair within 64 blocks, as its team's name tag
 //! visibility allows, in the team's colours, with its score in the
 //! objective displayed below names. Other players' names (on a LAN host
-//! or a server) show whenever `LivingEntityRenderer.shouldShowName` allows.
+//! or a server) show whenever `LivingEntityRenderer.shouldShowName` allows,
+//! and the player's own in third person with the `ownNameTag` extra.
 use super::{Game, view_vector};
 use horizon_client::{
     block_entity_render::vertex_light, hud::HudBatch, mesher::Vertex, mobs::Mob, save::uuid_text,
@@ -68,6 +69,27 @@ impl Game<'_> {
         }
         out
     }
+    /// Horizon's own name tag extra (`ownNameTag`): the player's own model and
+    /// name, while that model shows in third person. Vanilla never names the
+    /// camera entity (`LivingEntityRenderer.shouldShowName`).
+    fn own_name_tag(&self) -> Option<(&Mob, String)> {
+        if !self.settings.extras.own_name_tag
+            || self.camera_type.first_person()
+            || self.sleeping.is_some()
+            || self.spectator()
+            || self.potions.effects.get("invisibility").is_some()
+        {
+            return None;
+        }
+        let m = self.player_model.as_ref()?;
+        // The name others see: the profile's on a server (single player's
+        // server thread included), else the local player's.
+        let name = match self.remote.as_ref() {
+            Some(r) if !r.profile_name.is_empty() => r.profile_name.clone(),
+            _ => self.acting_player_name().to_owned(),
+        };
+        Some((m, name))
+    }
     /// The names the name tags show this frame (the control socket's status).
     pub(super) fn shown_name_tags(&self, camera: glam::DVec3) -> Vec<String> {
         self.name_tags(camera, 1.0)
@@ -88,7 +110,10 @@ impl Game<'_> {
             let at = glam::DVec3::new(m.position.x, m.position.y, m.position.z);
             (at.distance_squared(camera) < 64.0 * 64.0).then(|| (m, name.clone(), false))
         });
-        let players = players.into_iter().map(|(m, name)| (m, name, true));
+        let players = players
+            .into_iter()
+            .chain(self.own_name_tag())
+            .map(|(m, name)| (m, name, true));
         // Who is riding whom: asked once per tag below, and rescanning every mob
         // for each tag made this quadratic in the number of loaded mobs.
         let ridden: std::collections::HashSet<u32> =

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

@@ -506,8 +506,8 @@ impl Game<'_> {
     pub(super) fn list_native_mods(&mut self) {
         let mut mods = Vec::new();
         self.native_mods(&mut mods);
-        // A WebAssembly mod of the same id doesn't run (`start_mods`): the
-        // native row stands for it, and alone toggles its `mod.<id>` line.
+        // A WebAssembly mod of the same id: the native row stands for it,
+        // and alone toggles its `mod.<id>` line.
         self.settings
             .mods
             .installed
@@ -525,7 +525,6 @@ impl Game<'_> {
                 description: m.description,
                 problem: None,
                 dev: false,
-                has_settings: false,
                 native: Some(page),
             });
         }
@@ -575,11 +574,11 @@ impl Game<'_> {
         self.native_wheel(steps, &mut claimed);
         claimed
     }
-    /// A client mod's command: a native mod's first, then a WebAssembly mod's.
+    /// A native mod's command.
     pub(super) fn client_mod_command(&mut self, command: &str) -> bool {
         let mut ran = false;
         self.native_command(command, &mut ran);
-        ran || self.mod_command(command)
+        ran
     }
     /// The zoom in effect while playing (a native mod's); the spyglass's own
     /// view wins.

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

@@ -27,21 +27,15 @@ const MARGIN: f32 = 8.0;
 /// Items a panel may hold.
 const ITEMS: usize = 8192;
 
-/// Whose panel it is: a native mod's id, or a running WebAssembly mod's
-/// index.
+/// Whose panel it is: a native mod's id.
 #[derive(Clone, Debug, PartialEq)]
 pub(super) enum Owner {
     Native(String),
-    #[cfg(feature = "mods")]
-    Wasm(usize),
 }
 impl Owner {
-    fn native_id(&self) -> Option<&str> {
-        match self {
-            Owner::Native(id) => Some(id),
-            #[cfg(feature = "mods")]
-            Owner::Wasm(_) => None,
-        }
+    fn native_id(&self) -> &str {
+        let Owner::Native(id) = self;
+        id
     }
 }
 
@@ -61,9 +55,6 @@ pub(super) struct Shown {
 pub(super) struct Panel {
     /// A native mod's panel: the last one to show something.
     native: Option<Shown>,
-    /// A WebAssembly mod's, converted once per change.
-    #[cfg(feature = "mods")]
-    pub(super) wasm: Option<Shown>,
     /// The last native change.
     versions: u64,
     /// The items' owner and version they were made from.
@@ -79,16 +70,9 @@ pub(super) struct Panel {
 }
 
 impl Panel {
-    /// What the panel shows: a native mod's (one `on`), else a
-    /// WebAssembly mod's.
+    /// What the panel shows: a native mod's, one `on`.
     pub(super) fn shown(&self, on: impl Fn(&str) -> bool) -> Option<&Shown> {
-        let native = self
-            .native
-            .as_ref()
-            .filter(|s| s.owner.native_id().is_some_and(&on));
-        #[cfg(feature = "mods")]
-        let native = native.or(self.wasm.as_ref());
-        native
+        self.native.as_ref().filter(|s| on(s.owner.native_id()))
     }
     /// `native_panel_items`.
     pub(super) fn show_items(&mut self, mod_id: &str, mut items: Vec<BrowserStack>) {
@@ -111,7 +95,7 @@ impl Panel {
         let own = self
             .native
             .as_ref()
-            .is_some_and(|s| s.owner.native_id() == Some(mod_id));
+            .is_some_and(|s| s.owner.native_id() == mod_id);
         if !own {
             if !showing {
                 return None;
@@ -187,7 +171,6 @@ impl Game<'_> {
         if self.screen != Screen::Inventory || self.title.is_some() {
             return None;
         }
-        self.panel_wasm_sync();
         let disabled = &self.settings.mods.disabled;
         let Some(shown) = self.panel.shown(|id| !disabled.contains(id)) else {
             self.panel.of = None;
@@ -220,14 +203,8 @@ impl Game<'_> {
     }
     /// The player did `event` on `owner`'s panel.
     pub(super) fn panel_event(&mut self, owner: &Owner, event: BrowserEvent) {
-        match owner {
-            Owner::Native(id) => self.native_panel_event(id, &event),
-            #[cfg(feature = "mods")]
-            Owner::Wasm(i) => self
-                .mods
-                .mods
-                .browser_event(*i, super::mod_panel::event(event)),
-        }
+        let Owner::Native(id) = owner;
+        self.native_panel_event(id, &event);
     }
     /// The panel's parts: right of the window, from the top of the screen to
     /// the search box at its foot. None when the screen has no room for it.
@@ -470,6 +447,7 @@ impl Game<'_> {
         let shortcut = self.edit_shortcut(event);
         let ctrl = self.has_control_down();
         let shift = self.has_shift_down();
+        let types_text = self.types_text();
         let Some(search) = self.panel.search.as_mut() else {
             return;
         };
@@ -481,7 +459,7 @@ impl Game<'_> {
                 _ => false,
             };
             if !handled
-                && !ctrl
+                && types_text
                 && let Some(text) = &event.text
             {
                 let text: String = text.chars().filter(|c| !c.is_control()).collect();
@@ -550,7 +528,7 @@ impl Game<'_> {
         if self.screen != Screen::Inventory || self.title.is_some() || self.mod_browser_typing() {
             return;
         }
-        let Some(owner) = self.browser_sync().filter(|o| o.native_id().is_some()) else {
+        let Some(owner) = self.browser_sync() else {
             return;
         };
         if let Some(stack) = self.mod_browser_pointed() {
@@ -582,12 +560,6 @@ pub(super) fn browser_stack(
     })
 }
 
-/// No WebAssembly mods: no panel of theirs (`mod_panel.rs` with them).
-#[cfg(not(feature = "mods"))]
-impl Game<'_> {
-    fn panel_wasm_sync(&mut self) {}
-}
-
 #[cfg(test)]
 mod tests {
     use super::{BrowserStack, Owner, Panel, RecipePage};
@@ -655,40 +627,4 @@ mod tests {
         panel.show_items("recipes", Vec::new());
         assert!(panel.shown(|_| true).is_none());
     }
-
-    /// A native mod's panel wins over a WebAssembly mod's, and events go
-    /// back to a WebAssembly owner in the runtime's form.
-    #[cfg(feature = "mods")]
-    #[test]
-    fn native_owner_wins_over_webassembly() {
-        use super::{BrowserEvent, Shown};
-        use crate::game::mod_panel as wasm;
-        let mut panel = Panel {
-            wasm: Some(Shown {
-                owner: Owner::Wasm(0),
-                version: 7,
-                items: vec![stack("minecraft:stone")],
-                recipes: None,
-            }),
-            ..Panel::default()
-        };
-        let owner = |p: &Panel| p.shown(|_| true).map(|s| s.owner.clone());
-        assert_eq!(owner(&panel), Some(Owner::Wasm(0)));
-        panel.show_items("recipes", vec![stack("minecraft:dirt")]);
-        assert_eq!(owner(&panel), Some(Owner::Native("recipes".into())));
-        panel.show_items("recipes", Vec::new());
-        assert_eq!(owner(&panel), Some(Owner::Wasm(0)));
-
-        let event = BrowserEvent::SlotClicked {
-            recipe: 2,
-            slot: 9,
-            stack: stack("minecraft:oak_planks"),
-            right: true,
-        };
-        let horizon_mods::BrowserEvent::SlotClicked(c) = wasm::event(event) else {
-            panic!("a slot click");
-        };
-        assert_eq!((c.recipe, c.slot, c.right), (2, 9, true));
-        assert_eq!(c.stack.item, "minecraft:oak_planks");
-    }
 }

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

@@ -320,78 +320,3 @@ impl Game<'_> {
         }
     }
 }
-
-/// Capability `recipes` of WebAssembly mods: the same tables in the
-/// runtime's types.
-#[cfg(feature = "mods")]
-impl Game<'_> {
-    /// Capability `recipes`'s tables and known displays for this tick's
-    /// snapshot; nothing while no running mod reads them.
-    pub(super) fn mod_recipes(&mut self) -> (Option<Arc<horizon_mods::Recipes>>, Arc<[i32]>) {
-        if !self.mods.mods.wants_recipes() || self.res.rest.get().is_none() {
-            return (None, Arc::from([]));
-        }
-        if self.mods.recipes.is_none() {
-            self.mods.recipes = self.made_recipes().map(|t| Arc::new(wasm::recipes(&t)));
-        }
-        (self.mods.recipes.clone(), self.known_displays())
-    }
-}
-
-/// The native tables as the WebAssembly runtime's.
-#[cfg(feature = "mods")]
-mod wasm {
-    use super::{Recipe, RecipeItem, RecipeKind, RecipeStack, Recipes};
-    use horizon_mods as m;
-
-    fn kind(k: RecipeKind) -> m::RecipeKind {
-        match k {
-            RecipeKind::CraftingShaped => m::RecipeKind::CraftingShaped,
-            RecipeKind::CraftingShapeless => m::RecipeKind::CraftingShapeless,
-            RecipeKind::Smelting => m::RecipeKind::Smelting,
-            RecipeKind::Blasting => m::RecipeKind::Blasting,
-            RecipeKind::Smoking => m::RecipeKind::Smoking,
-            RecipeKind::Campfire => m::RecipeKind::Campfire,
-            RecipeKind::Stonecutting => m::RecipeKind::Stonecutting,
-            RecipeKind::Smithing => m::RecipeKind::Smithing,
-            RecipeKind::Brewing => m::RecipeKind::Brewing,
-        }
-    }
-    fn stacks(list: &[RecipeStack]) -> Vec<m::RecipeStack> {
-        list.iter()
-            .map(|s| m::RecipeStack {
-                item: s.item,
-                count: s.count,
-                components: s.components.clone(),
-            })
-            .collect()
-    }
-    fn recipe(r: &Recipe) -> m::Recipe {
-        m::Recipe {
-            id: r.id.clone(),
-            kind: kind(r.kind),
-            category: r.category.clone(),
-            group: r.group.clone(),
-            width: r.width,
-            height: r.height,
-            slots: r.slots.iter().map(|s| stacks(s)).collect(),
-            results: stacks(&r.results),
-            cooking_time: r.cooking_time,
-            experience: r.experience,
-            book_id: r.book_id,
-        }
-    }
-    fn item(i: &RecipeItem) -> m::RecipeItem {
-        m::RecipeItem {
-            id: i.id.clone(),
-            name: i.name.clone(),
-            tags: i.tags.clone(),
-        }
-    }
-    pub(super) fn recipes(t: &Recipes) -> m::Recipes {
-        m::Recipes {
-            items: t.items.iter().map(item).collect(),
-            recipes: t.recipes.iter().map(recipe).collect(),
-        }
-    }
-}

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

@@ -19,12 +19,18 @@ pub(super) const CONTROL_HELP: &[&str] = &[
 impl Game<'_> {
     pub(super) fn save_title_options(&mut self) {
         if let Some(title) = &self.title
-            && title.last_server != self.settings.file.string("lastServer")
+            && (title.last_server != self.settings.file.string("lastServer")
+                || title.skip_multiplayer_warning
+                    != self.settings.file.bool("skipMultiplayerWarning"))
         {
             self.settings.file.set(
                 "lastServer",
                 horizon_client::options_file::V::Str(title.last_server.clone()),
             );
+            self.settings.file.set(
+                "skipMultiplayerWarning",
+                horizon_client::options_file::V::Bool(title.skip_multiplayer_warning),
+            );
             self.settings.save(&Self::options_path());
         }
     }
@@ -196,7 +202,6 @@ impl Game<'_> {
                 Event::Changed => {
                     self.settings.save(&Self::options_path());
                     self.apply_settings();
-                    self.sync_mods();
                     self.sync_agent_control();
                     self.ui.options.agent_status = self.agent_status_lines();
                 }
@@ -257,7 +262,6 @@ impl Game<'_> {
                     let _ = std::fs::create_dir_all(&dir);
                     super::packs::open_folder(&dir);
                 }
-                Event::ModSettings(i) => self.open_mod_screen(i, true),
                 Event::NativeSettings(i) => self.native_settings_refresh(i),
                 Event::NativeButton(i, b) => self.native_settings_event(i, b),
                 Event::Credits => self.open_win_screen(false, super::win::Finish::Options),
@@ -290,8 +294,10 @@ impl Game<'_> {
             );
             r.set_hdr(
                 s.horizon.hdr,
-                s.horizon.hdr_paper_white as f32,
-                s.horizon.hdr_peak as f32,
+                s.horizon.paper_white_nits() as f32,
+                s.horizon.peak_nits() as f32,
+                s.horizon.hdr_black_level as f32 / 100.0,
+                s.horizon.hdr_ui_brightness as f32 / 100.0,
                 &Self::options_path().with_file_name(horizon_client::graphics::HDR_MARKER),
             );
         }

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

@@ -822,6 +822,10 @@ impl Game<'_> {
             return;
         }
         self.pad.menu.os_hidden = !show;
+        // Controller menus leave the native pointer to its owning player.
+        if !self.keyboard_mouse {
+            return;
+        }
         if let Some(window) = &self.window {
             window.set_cursor_visible(show && !self.captured);
         }

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

@@ -122,6 +122,17 @@ impl CameraType {
         }
     }
 }
+/// `LivingEntityRenderer.isBodyVisible` and `isInvisibleTo` for the player's
+/// own body, seen by itself: the Invisibility effect (`Entity.isInvisible`)
+/// hides it unless its team sees friendly invisibles, where vanilla draws it
+/// translucent.
+fn body_visible(
+    effects: &horizon_client::effects::PlayerEffects,
+    team: Option<&horizon_client::scoreboard::Team>,
+) -> bool {
+    let invisible = effects.get("invisibility").is_some();
+    !horizon_client::scoreboard::invisible_to(team, team, false, invisible)
+}
 /// The player's model type (`PlayerModel` with the default skin).
 pub(super) fn player_type(root: &Path) -> Option<Arc<MobType>> {
     let models = horizon_client::mobs::EntityModelDocument::load(root).ok()?;
@@ -316,6 +327,11 @@ impl Game<'_> {
     /// Keep the player's model in step with the player (`LivingEntity.tick`
     /// body turning, `WalkAnimationState`, the swing and the pose).
     pub(super) fn tick_player_model(&mut self) {
+        let scale = self
+            .player
+            .as_mut()
+            .and_then(|p| p.attribute("minecraft:scale").ok())
+            .unwrap_or(1.0) as f32;
         let Some(p) = self.player.as_ref() else {
             self.player_model = None;
             return;
@@ -370,6 +386,7 @@ impl Game<'_> {
             return;
         };
         m.extra.ints[1] = bed;
+        m.extra.model_scale = scale;
         let at = Vec3::new(
             position.x,
             position.y - if crouching { 0.125 } else { 0.0 },
@@ -454,17 +471,28 @@ impl Game<'_> {
     pub(super) fn own_body_in_view(&self) -> bool {
         !self.camera_type.first_person() || self.sleeping.is_some()
     }
-    /// Whether the player's own model shows in the world view.
+    /// Whether the player's own model shows in the world view (its body or,
+    /// while invisible, only its armour and held items).
     pub(super) fn player_model_shown(&self) -> bool {
         // A shader pack's shadow pass draws the player in first person too (shadowPlayer).
         (self.own_body_in_view() || self.pack_shadow_casters.1)
             && !self.spectator()
-            && self.potions.effects.get("minecraft:invisibility").is_none()
             && self
                 .player
                 .as_ref()
                 .is_some_and(|p| !p.health.dead_or_dying())
     }
+    /// The player's own team: a server's client is in it by its profile name.
+    fn own_team(&self) -> Option<&horizon_client::scoreboard::Team> {
+        match &self.remote {
+            Some(r) => self.score.board.players_team(&r.profile_name),
+            None => self.player_team(),
+        }
+    }
+    /// Whether the player's own body is drawn (`body_visible`).
+    pub(super) fn own_body_visible(&self) -> bool {
+        body_visible(&self.potions.effects, self.own_team())
+    }
     /// The player's model for the entity pass in third person.
     pub(super) fn player_model_geometry(
         &self,
@@ -487,7 +515,13 @@ impl Game<'_> {
         let atlas = &self.gui.atlas;
         let lookup = |name: &str| atlas.sprites.get(name).map(|r| [r.u0, r.v0, r.u1, r.v1]);
         let start = out.len();
-        horizon_client::mobs::render::render_with(
+        let body = self.own_body_visible();
+        let render = if body {
+            horizon_client::mobs::render::render_with
+        } else {
+            horizon_client::mobs::render::render_layers
+        };
+        render(
             m,
             alpha as f32,
             camera,
@@ -498,18 +532,32 @@ impl Game<'_> {
             out,
         );
         let chest = self.armor[1].as_ref().map(|s| &*s.item);
-        self.player_cape_geometry(m, chest, camera, alpha as f32, packed, out);
+        // CapeLayer: no cape on an invisible player (`isInvisible`, whoever looks).
+        if self.potions.effects.get("invisibility").is_none() {
+            self.player_cape_geometry(m, chest, camera, alpha as f32, packed, out);
+        }
         self.player_elytra_geometry(m, chest, camera, alpha as f32, packed, out);
         self.spin_attack_geometry(m, camera, alpha as f32, packed, out);
         self.held_item_geometry(m, camera, alpha, packed, true, out);
-        // LivingEntity.isCurrentlyGlowing: the Glowing effect. A server's client is
-        // in its team by its profile name.
+        // LivingEntity.isCurrentlyGlowing: the Glowing effect.
         if self.potions.effects.get("glowing").is_some() {
-            let team = match &self.remote {
-                Some(r) => self.score.board.players_team(&r.profile_name),
-                None => self.player_team(),
-            };
-            self.mark_outline(&out[start..], super::glowing::team_color(team));
+            let color = super::glowing::team_color(self.own_team());
+            // LivingEntityRenderer.getRenderType: an invisible glowing body
+            // still draws its outline.
+            if !body {
+                let mut silhouette = Vec::new();
+                horizon_client::mobs::render::render(
+                    m,
+                    alpha as f32,
+                    camera,
+                    &lookup,
+                    packed,
+                    self.res.mob_data(),
+                    &mut silhouette,
+                );
+                self.mark_outline(&silhouette, color);
+            }
+            self.mark_outline(&out[start..], color);
         }
     }
     /// `extractEntityInInventoryFollowsMouse`: the player in the box
@@ -540,6 +588,9 @@ impl Game<'_> {
         let x_angle = ((cx - self.cursor.0) / 40.0).atan();
         let y_angle = ((cy - self.cursor.1) / 40.0).atan();
         let mut m = m.clone();
+        // `extractEntityInInventory` divides the size by the entity's scale: the
+        // preview is the same size whatever the player's scale.
+        m.extra.model_scale = 0.0;
         // The render state: still, facing out, the head toward the cursor.
         m.previous = m.position;
         m.body_yaw = 180.0 + x_angle * 20.0;
@@ -554,7 +605,13 @@ impl Game<'_> {
         let atlas = &self.gui.atlas;
         let lookup = |name: &str| atlas.sprites.get(name).map(|r| [r.u0, r.v0, r.u1, r.v1]);
         let mut verts = Vec::new();
-        horizon_client::mobs::render::render_with(
+        // The same render state as in the world: an invisible body is not drawn.
+        let render = if self.own_body_visible() {
+            horizon_client::mobs::render::render_with
+        } else {
+            horizon_client::mobs::render::render_layers
+        };
+        render(
             &m,
             1.0,
             camera,
@@ -565,7 +622,9 @@ impl Game<'_> {
             &mut verts,
         );
         let chest = self.armor[1].as_ref().map(|s| &*s.item);
-        self.player_cape_geometry(&m, chest, camera, 1.0, 240 | 240 << 8, &mut verts);
+        if self.potions.effects.get("invisibility").is_none() {
+            self.player_cape_geometry(&m, chest, camera, 1.0, 240 | 240 << 8, &mut verts);
+        }
         self.player_elytra_geometry(&m, chest, camera, 1.0, 240 | 240 << 8, &mut verts);
         self.held_item_geometry(&m, camera, 1.0, 240 | 240 << 8, false, &mut verts);
         let height = if m.extra.crouching { 1.5 } else { 1.8 };
@@ -872,6 +931,73 @@ mod preview_tests {
         }
     }
 
+    #[test]
+    fn an_invisible_player_hides_its_own_body() {
+        use horizon_client::{effects::EffectInstance, scoreboard::Scoreboard};
+        // The effect as a server's UpdateMobEffect or a drunk potion adds it.
+        let id = horizon_client::brewing::effect("minecraft:invisibility")
+            .unwrap()
+            .id;
+        let mut effects = horizon_client::effects::PlayerEffects::default();
+        assert!(body_visible(&effects, None));
+        effects.add(EffectInstance::new(id, 3600, 0));
+        assert!(!body_visible(&effects, None), "no team: the body is hidden");
+        // Entity.isInvisibleTo: a team that sees friendly invisibles sees it.
+        let mut board = Scoreboard::default();
+        let team = board.add_team("blue");
+        assert!(body_visible(&effects, Some(team)));
+        team.see_friendly_invisibles = false;
+        assert!(!body_visible(&effects, Some(team)));
+    }
+
+    /// LivingEntityRenderer.submit: an invisible body is not drawn, its
+    /// HumanoidArmorLayer is.
+    #[test]
+    fn an_invisible_body_keeps_its_armour() {
+        let root = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("../../.local/horizon-client/26.3");
+        let Some(kind) = player_type(&root) else {
+            return;
+        };
+        let m = Mob::new(1, kind.clone(), Vec3::ZERO, 0.0);
+        let armour = [(&*kind.model, [0.5, 0.5, 0.75, 0.75], u32::MAX)];
+        let atlas = |_: &str| Some([0.0, 0.0, 0.25, 0.25]);
+        let data = horizon_client::mobs::MobData {
+            states: Vec::new(),
+            placements: Default::default(),
+            heightmaps: Default::default(),
+            animations: Default::default(),
+            biome_tags: Default::default(),
+            entity_tags: Default::default(),
+            villager_hats: Default::default(),
+            pois: Default::default(),
+        };
+        let draw = |body: bool| {
+            let mut out = Vec::new();
+            let render = if body {
+                horizon_client::mobs::render::render_with
+            } else {
+                horizon_client::mobs::render::render_layers
+            };
+            render(
+                &m,
+                1.0,
+                glam::DVec3::ZERO,
+                &atlas,
+                0xF0F0,
+                &data,
+                &armour,
+                &mut out,
+            );
+            out
+        };
+        let (shown, hidden) = (draw(true), draw(false));
+        assert!(shown.iter().any(|v| v.uv[0] <= 0.25), "the body draws");
+        assert!(!hidden.is_empty(), "the armour still draws");
+        assert!(hidden.iter().all(|v| v.uv[0] >= 0.5), "only the armour");
+        assert_eq!(hidden.len() * 2, shown.len());
+    }
+
     #[test]
     fn burning_inventory_preview_keeps_visible_fullbright_flames() {
         let rect = |u0| horizon_client::hud::Rect {

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

@@ -180,6 +180,7 @@ impl Game<'_> {
         }
         let ctrl = self.has_control_down();
         let shift = self.has_shift_down();
+        let types_text = self.types_text();
         let Some(search) = self.recipe_ui.search.as_mut() else {
             return;
         };
@@ -188,7 +189,7 @@ impl Game<'_> {
             _ => false,
         };
         if !handled
-            && !ctrl
+            && types_text
             && let Some(text) = &event.text
         {
             let text: String = text.chars().filter(|c| !c.is_control()).collect();
@@ -338,7 +339,7 @@ impl Game<'_> {
         ui.client_known = Some(known.clone());
         ui.client_version += 1;
     }
-    /// Every entry of the book, in its order (capability `recipes`).
+    /// Every entry of the book, in its order (`native_recipes`).
     pub(super) fn recipe_book_entries(&mut self) -> Vec<Entry> {
         self.ensure_book();
         self.recipe_ui
@@ -347,7 +348,7 @@ impl Game<'_> {
             .map_or_else(Vec::new, |b| b.entries.clone())
     }
     /// The display ids the player's book holds, and a number that changes
-    /// whenever they do (capability `recipes`).
+    /// whenever they do (`native_known_recipes`).
     pub(super) fn recipe_book_displays(&mut self) -> (u64, Vec<i32>) {
         self.sync_client_book();
         (
@@ -861,14 +862,14 @@ impl Game<'_> {
         self.recipe_ui.ghost.clear();
         self.place_recipe(book_type, entry_index, use_max);
     }
-    /// Whether the open screen takes `recipes.place`: a crafting grid's
+    /// Whether the open screen takes `native_place_recipe`: a crafting grid's
     /// book (the inventory's or a crafting table's).
     pub(super) fn mod_recipe_screen(&self) -> bool {
         self.screen == Screen::Inventory
             && self.active_book() == Some(BookType::Crafting)
             && !self.spectator()
     }
-    /// `recipes.place`: the book's click on the recipe with this display
+    /// `native_place_recipe`: the book's click on the recipe with this display
     /// id, refused as `handlePlaceRecipe` refuses it (no crafting screen,
     /// not in the player's book; an impossible one in `place_recipe`).
     pub(super) fn mod_place_recipe(&mut self, display_id: i32, all: bool) {

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

@@ -325,7 +325,9 @@ impl Game<'_> {
                     &self.options.resources,
                 ));
             }
+            let skip = self.settings.file.bool("skipMultiplayerWarning");
             if let Some(title) = &mut self.title {
+                title.skip_multiplayer_warning = skip;
                 title.failed(error);
             }
             self.capture(false);
@@ -556,6 +558,8 @@ impl Game<'_> {
         self.titles.overlay_time = 0;
         // GameRenderer.resetData (Minecraft.disconnect).
         self.item_activation.reset();
+        // A world is leaving either way: its icon attempt goes with it.
+        self.world_icon = None;
         if let Some(mut r) = self.remote.take() {
             r.session.disconnect();
         }
@@ -608,6 +612,7 @@ impl Game<'_> {
         let saves = std::env::current_dir()?.join("saves");
         let mut title = horizon_client::title::Title::new(saves.clone(), &self.options.resources);
         title.last_server = self.settings.file.string("lastServer");
+        title.skip_multiplayer_warning = self.settings.file.bool("skipMultiplayerWarning");
         if single_player && reason.is_none() {
             self.title = Some(title);
             self.capture(false);
@@ -752,9 +757,6 @@ impl Game<'_> {
             self.ticks,
             self.screen == Screen::Chat,
         );
-        if self.mods.running() {
-            self.mods_chat(&text);
-        }
         if let Some(r) = self.remote.as_mut() {
             r.chat.push((text, Instant::now()));
             r.chat_received += 1;
@@ -1012,7 +1014,12 @@ impl Game<'_> {
         if self.remote.is_none() {
             return;
         }
-        let Some((id, command)) = self.ui.chat_screen.as_mut().and_then(|s| s.take_request())
+        let Some((id, command)) = self
+            .ui
+            .chat_screen
+            .as_mut()
+            .and_then(|s| s.take_request())
+            .or_else(|| self.command_block_suggestion_request())
         else {
             return;
         };
@@ -1052,7 +1059,8 @@ impl Game<'_> {
         })();
         if let Ok((id, start, length, list)) = decoded {
             let range = (start.max(0) as usize, length.max(0) as usize);
-            self.chat_server_suggestions(id, range, list);
+            self.chat_server_suggestions(id, range, list.clone());
+            self.command_block_server_suggestions(id, range, list);
         }
     }
     fn set_registries(&mut self, registries: Arc<Dynamic>) {
@@ -1247,10 +1255,15 @@ impl Game<'_> {
                 }
                 _ => {}
             }
+            let command_block = matches!(loaded, BlockEntity::CommandBlock(_));
             self.world.block_entities.insert(key, loaded);
+            self.update_spawner_display(key);
             // The section is drawn again with what the block entity shows.
             let state = self.world.block(pos[0], pos[1], pos[2]);
             let _ = self.world.set(pos[0], pos[1], pos[2], state);
+            if command_block {
+                self.command_block_data_arrived(key);
+            }
         }
     }
     /// `handleAnimate`: a player wakes up, or an entity gets the critical
@@ -2875,7 +2888,6 @@ impl Game<'_> {
                 if let Some(r) = self.remote.as_mut() {
                     r.commands = Some(tree);
                 }
-                self.merge_remote_tree();
             }
             C::Cooldown(p) => {
                 // ClientPacketListener.handleItemCooldown: the server starts
@@ -3725,8 +3737,8 @@ impl Game<'_> {
     pub(super) fn tick_remote(&mut self) -> Result<()> {
         self.tick_remote_level()?;
         // Client mods tick on any server, single player's own included.
-        self.tick_mods();
         self.native_tick();
+        self.tell_native_now();
         // Minecraft.tick sends this even when the player cannot tick yet,
         // including while waiting for chunks. Keep it outside early returns.
         if self.remote.as_ref().is_some_and(|r| r.joined) {
@@ -3802,6 +3814,7 @@ impl Game<'_> {
         // and the moving pistons a block event's client-side moveBlocks made
         // (their progress advances between the server's block updates).
         self.tick_block_entity_anims();
+        self.tick_remote_spawners();
         self.client_tick_beacons();
         self.with_level(|b, level, ticks| {
             b.client_tick_block_entities(level, ticks);
@@ -3820,6 +3833,7 @@ impl Game<'_> {
         self.tick_subtitles();
         let entity_collisions = self.player_entity_collisions();
         let pushed = self.remote_pushes();
+        let sprint_window = self.settings.sprint_window;
         let Some(player) = self.player.as_mut() else {
             return Ok(());
         };
@@ -3918,7 +3932,7 @@ impl Game<'_> {
                 collision_binding: self.collision,
                 resources: self.motion,
             }
-            .controlled_simulation_tick(keys)?;
+            .controlled_simulation_tick_with_sprint_window(keys, sprint_window)?;
         } else {
             // LivingEntity.baseTick counts hurtTime down for a dead or riding
             // player too (controlled_simulation_tick does it otherwise): left
@@ -5794,7 +5808,7 @@ impl Game<'_> {
     }
     /// MultiPlayerGameMode.dropItem (key.drop): predict the removal, then send
     /// the action; swing only if a nonempty stack was removed.
-    fn remote_drop(&mut self, all: bool) {
+    pub(super) fn remote_drop(&mut self, all: bool) {
         let dropped =
             horizon_client::items::take_held_drop(&mut self.inventory[self.selected], all, false);
         self.send(S::PlayerAction(play::PlayerAction {
@@ -5883,22 +5897,23 @@ impl Game<'_> {
             .iter()
             .map(|&(slot, button, input)| (slot, button, input, Vec::new(), self.carried.clone()))
             .collect();
+        let mut threw = false;
         // The engine's slot indices are the menu's own, as on the network.
         self.menu_session(|m, env, _| {
-            let mut predicted = Vec::with_capacity(clicks.len());
-            for &(slot, button, input) in &clicks {
-                let before = menu_items(m);
-                if m.click(env, i32::from(slot), button, input).is_err() {
-                    // The server throws on it too: nothing is predicted.
-                    return Some(false);
-                }
-                let changed = changed_slots(&before, m);
-                predicted.push((slot, button, input, changed, m.carried.clone()));
-            }
+            let Some((predicted, dropped)) = predict_clicks(m, env, &clicks) else {
+                // The server throws on it too: nothing is predicted.
+                return Some(false);
+            };
             sent = predicted;
+            threw = dropped;
             Some(true)
         });
         self.send_clicks(container, sent);
+        // LivingEntity.drop(.., Prediction.PREDICTED): the client swings its own
+        // main hand; the server shows the swing only to the other players.
+        if threw {
+            self.swing_hand(Hand::Main, SwingAnimation::DEFAULT);
+        }
         true
     }
     /// A Shift double click on a server (`AbstractContainerScreen.mouseReleased`):
@@ -6447,8 +6462,9 @@ impl Game<'_> {
                 .collect::<Vec<_>>(),
             // The player's own model exists (third person and the inventory draw it).
             "player_model": self.player_model.is_some(),
-            // The world view draws it now (third person, or lying in a bed).
-            "own_body": self.player_model_shown(),
+            // The world view draws its body now (third person, or lying in a bed;
+            // not while invisible).
+            "own_body": self.player_model_shown() && self.own_body_visible(),
             "text_display_vertices": self.text_display_vertices,
             "text_displays": self.text_displays.len(),
             "health": r.health.0,
@@ -6550,6 +6566,30 @@ fn creative_sync_slot(i: usize) -> i16 {
     }) as i16
 }
 
+/// `MultiPlayerGameMode.handleContainerInput` for each click on the engine's
+/// copy of the menu: the click with the slots it changed and the carried
+/// stack after it, and whether a click dropped a stack. Every drop of
+/// `AbstractContainerMenu.doClick` (a THROW, a click outside the window, a
+/// swap or a result move with no room left) is `Prediction.PREDICTED`.
+/// None when the engine refuses a click.
+fn predict_clicks(
+    m: &mut horizon_client::menu::Menu,
+    env: &horizon_client::menu::Env,
+    clicks: &[(i16, i32, Input)],
+) -> Option<(Vec<Predicted>, bool)> {
+    let mut predicted = Vec::with_capacity(clicks.len());
+    let mut dropped = false;
+    for &(slot, button, input) in clicks {
+        let before = menu_items(m);
+        let thrown = m.dropped.len();
+        m.click(env, i32::from(slot), button, input).ok()?;
+        dropped |= m.dropped.len() > thrown;
+        let changed = changed_slots(&before, m);
+        predicted.push((slot, button, input, changed, m.carried.clone()));
+    }
+    Some((predicted, dropped))
+}
+
 fn menu_items(m: &horizon_client::menu::Menu) -> Vec<Option<ItemStack>> {
     (0..m.slot_count()).map(|i| m.slot(i).cloned()).collect()
 }
@@ -6845,6 +6885,66 @@ impl Remote {
 mod tests {
     use super::Game;
 
+    /// Q over a slot of the inventory on a server (#3357): the predicted THROW
+    /// drops the stack, so the player's hand swings, as `LivingEntity.drop`
+    /// does for `Prediction.PREDICTED`; a plain pick up drops nothing.
+    #[test]
+    fn a_predicted_throw_from_a_slot_swings_the_hand() {
+        use horizon_client::{
+            banner::Banners,
+            brewing::Brewing,
+            crafting::Recipes,
+            creative::Names,
+            enchant::Enchantments,
+            items::{ItemStack, Items},
+            menu::{Env, Input, Kind, Menu},
+            stations::StationRecipes,
+        };
+        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 items = Items::catalog(&root).unwrap();
+        let recipes = Recipes::load(&root, &items).unwrap();
+        let brewing = Brewing::load(&root, &items);
+        let banners = Banners::load(&root);
+        let station_recipes = StationRecipes::load(&root, &items);
+        let enchantments = Enchantments::default();
+        let names = Names::default();
+        let env = Env {
+            items: &items,
+            recipes: &recipes,
+            brewing: &brewing,
+            banners: &banners,
+            station_recipes: &station_recipes,
+            enchantments: &enchantments,
+            names: &names,
+            trade: None,
+            maps: None,
+        };
+        let mut menu = Menu::new(Kind::Inventory);
+        let cobblestone = ItemStack {
+            item: "minecraft:cobblestone".into(),
+            count: 16,
+            damage: 0,
+            extra: None,
+        };
+        // The first hotbar slot of InventoryMenu.
+        menu.set_slot(&env, 36, Some(cobblestone));
+        let (sent, threw) =
+            super::predict_clicks(&mut menu, &env, &[(36, 0, Input::Throw)]).unwrap();
+        assert!(threw, "Q over a slot drops one and swings");
+        assert_eq!(menu.slot(36).map(|s| s.count), Some(15));
+        assert_eq!(sent.len(), 1);
+        let (_, threw) = super::predict_clicks(&mut menu, &env, &[(36, 0, Input::Pickup)]).unwrap();
+        assert!(!threw, "picking the stack up drops nothing");
+        let (_, threw) =
+            super::predict_clicks(&mut menu, &env, &[(-999, 1, Input::Pickup)]).unwrap();
+        assert!(threw, "one of the carried stack outside the window");
+    }
+
     #[test]
     fn placement_preview_checks_obstruction_without_changing_the_level() {
         use super::DryLevel;

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

@@ -135,6 +135,7 @@ impl Game<'_> {
                     continue;
                 };
                 match (index, value) {
+                    (0, Value::Byte(flags)) => f.invisible = (*flags as u8 & 0x20) != 0,
                     (8, Value::Id(d)) => f.facing = (*d).clamp(0, 5) as u8,
                     (10, Value::Int(r)) => f.rotation = r.rem_euclid(8) as u8,
                     _ => {}

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

@@ -22,8 +22,7 @@ impl Screen {
             | Self::Friends
             | Self::ServerLinks
             | Self::ConfirmLink
-            | Self::DialogWarning
-            | Self::Mod => true,
+            | Self::DialogWarning => true,
             Self::Playing
             | Self::GameModeSwitcher
             | Self::Chat

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

@@ -1,576 +0,0 @@
-//! Server mods in the game (`docs/mods.md`, "Server mods"): the game that
-//! simulates the world (in-frame single player, the server thread, a LAN
-//! host, the dedicated server) runs them. At the end of each tick it tells
-//! them who joined and left, then what players said, broke and placed since
-//! the last one, then ticks them; a player's command reaches them at once.
-//! Their lines go to the players they name. With no server mod on, each hook
-//! here is one check.
-use super::{Game, lan::LanHost};
-#[cfg(not(feature = "mods"))]
-use horizon_world::registry::BlockStateId;
-
-/// Who did something a server mod hears about, resolved at the tick's end.
-#[cfg_attr(not(feature = "mods"), allow(dead_code))]
-pub(super) enum Who {
-    /// The window's own player, in-frame.
-    Local,
-    /// A connection's player (the server thread's owner is one).
-    Conn(u32),
-    Uuid(u128),
-}
-
-/// What players did during a tick, for the server mods at its end.
-#[cfg_attr(not(feature = "mods"), allow(dead_code))]
-pub(super) enum ModEvent {
-    Chat(Who, String),
-    Block {
-        who: Who,
-        pos: [i32; 3],
-        state: String,
-        placed: bool,
-    },
-}
-
-#[cfg(not(feature = "mods"))]
-impl Game<'_> {
-    pub(super) fn tick_server_mods(&mut self) {}
-    pub(super) fn mod_block_event(&mut self, _pos: [i32; 3], _state: BlockStateId, _placed: bool) {}
-    pub(super) fn mod_player_chat(&mut self, _who: Who, _text: &str) {}
-    pub(super) fn local_server_mod_command(&mut self, _line: &str) -> bool {
-        false
-    }
-    pub(super) fn guest_server_mod_command(
-        &mut self,
-        _host: &mut LanHost,
-        _conn: u32,
-        _line: &str,
-    ) -> bool {
-        false
-    }
-    pub(super) fn apply_mod_block_writes(&mut self) {}
-}
-
-#[cfg(feature = "mods")]
-mod run {
-    use super::{Game, LanHost, ModEvent, Who};
-    use horizon_client::chunk_map::ChunkMap;
-    use horizon_client::{
-        command::args::GameMode as Mode,
-        lan::data::component_nbt,
-        text::{self, Text},
-    };
-    use horizon_mods::{
-        ArgumentKind, BlockPos, GameMode, Output, ServerCommand, ServerPlayer, WorldView,
-    };
-    use horizon_protocol::packets::play::{self, Clientbound as C};
-    use horizon_world::registry::{BlockRegistry, BlockStateId};
-    use serde_json::{Value, json};
-
-    /// Blocks queued for levels that don't tick (another dimension, in-frame)
-    /// are kept up to this many; the oldest go first.
-    const MAX_QUEUED_WRITES: usize = 1 << 16;
-
-    /// Capability `world`'s view during a call: the levels' chunks, moved out
-    /// of the game for the call and back after it (no copy).
-    struct LentWorld {
-        registry: &'static BlockRegistry,
-        biomes: std::sync::Arc<horizon_client::biome::Biomes>,
-        dims: Vec<(&'static str, ChunkMap)>,
-    }
-    impl WorldView for LentWorld {
-        fn block(&self, dimension: &str, x: i32, y: i32, z: i32) -> Option<String> {
-            let (_, chunks) = self.dims.iter().find(|(d, _)| *d == dimension)?;
-            let chunk = chunks.get(&(x >> 4, z >> 4))?;
-            Some(state_string(self.registry, chunk.block(x & 15, y, z & 15)))
-        }
-        fn biome(&self, dimension: &str, x: i32, y: i32, z: i32) -> Option<String> {
-            let (_, chunks) = self.dims.iter().find(|(d, _)| *d == dimension)?;
-            let chunk = chunks.get(&(x >> 4, z >> 4))?;
-            Some(self.biomes.get(chunk.biome(x, y, z)).name.clone())
-        }
-        fn has_dimension(&self, dimension: &str) -> bool {
-            matches!(
-                dimension,
-                "minecraft:overworld" | "minecraft:the_nether" | "minecraft:the_end"
-            )
-        }
-        fn check_state(&self, state: &str) -> Result<(), String> {
-            crate::game::render_control::parse_state(self.registry, state)
-                .map(drop)
-                .map_err(|e| format!("{state}: {e}"))
-        }
-    }
-
-    /// Server mods' commands as a root of the commands report
-    /// (`lan::commands`): a literal per command, then its arguments in a
-    /// chain, each node runnable where only optional arguments follow.
-    fn command_tree<'a>(commands: impl Iterator<Item = &'a ServerCommand>) -> Value {
-        let mut root = serde_json::Map::new();
-        for c in commands {
-            let mut next: Option<(String, Value)> = None;
-            for (i, a) in c.arguments.iter().enumerate().rev() {
-                let executable = c.arguments.get(i + 1).is_none_or(|b| b.optional);
-                let (parser, properties) = match a.kind {
-                    ArgumentKind::Word => ("brigadier:string", json!({"type": "word"})),
-                    ArgumentKind::Text => ("brigadier:string", json!({"type": "greedy"})),
-                    ArgumentKind::Integer((min, max)) => {
-                        let mut p = serde_json::Map::new();
-                        if let Some(min) = min {
-                            p.insert("min".into(), min.into());
-                        }
-                        if let Some(max) = max {
-                            p.insert("max".into(), max.into());
-                        }
-                        ("brigadier:integer", Value::Object(p))
-                    }
-                    ArgumentKind::Number => ("brigadier:double", Value::Null),
-                    ArgumentKind::Boolean => ("brigadier:bool", Value::Null),
-                    ArgumentKind::Player => (
-                        "minecraft:entity",
-                        json!({"amount": "single", "type": "players"}),
-                    ),
-                    ArgumentKind::BlockPos => ("minecraft:block_pos", Value::Null),
-                };
-                let mut node = json!({
-                    "type": "argument",
-                    "parser": parser,
-                    "properties": properties,
-                    "executable": executable,
-                });
-                if let Some((name, child)) = next.take() {
-                    node["children"] = json!({ name: child });
-                }
-                next = Some((a.name.clone(), node));
-            }
-            let executable = c.arguments.first().is_none_or(|a| a.optional);
-            let mut literal = json!({"type": "literal", "executable": executable});
-            if let Some((name, child)) = next {
-                literal["children"] = json!({ name: child });
-            }
-            root.insert(c.name.clone(), literal);
-        }
-        if root.is_empty() {
-            return Value::Null;
-        }
-        json!({"type": "root", "children": root})
-    }
-
-    /// `minecraft:oak_log[axis=y]`.
-    fn state_string(registry: &BlockRegistry, state: BlockStateId) -> String {
-        let Some(s) = registry.state(state) else {
-            return "minecraft:air".into();
-        };
-        if s.properties.is_empty() {
-            return s.name.clone();
-        }
-        let props: Vec<String> = s
-            .properties
-            .iter()
-            .map(|(k, v)| format!("{k}={v}"))
-            .collect();
-        format!("{}[{}]", s.name, props.join(","))
-    }
-
-    /// `UUID.toString()`.
-    fn uuid_string(u: u128) -> String {
-        let h = format!("{u:032x}");
-        format!(
-            "{}-{}-{}-{}-{}",
-            &h[..8],
-            &h[8..12],
-            &h[12..16],
-            &h[16..20],
-            &h[20..]
-        )
-    }
-
-    fn mode(id: i32) -> GameMode {
-        match id {
-            1 => GameMode::Creative,
-            2 => GameMode::Adventure,
-            3 => GameMode::Spectator,
-            _ => GameMode::Survival,
-        }
-    }
-
-    impl Game<'_> {
-        /// The players on this game's server: the window's own player
-        /// in-frame, then every connection's. `host` is the hub when it is
-        /// out of `self.lan`.
-        pub(in crate::game) fn server_players(&self, host: Option<&LanHost>) -> Vec<ServerPlayer> {
-            let mut out = Vec::new();
-            if self.options.execution_role.is_client()
-                && self.remote.is_none()
-                && let Some(p) = &self.player
-            {
-                out.push(ServerPlayer {
-                    id: uuid_string(self.player_uuid()),
-                    name: crate::game::chat::PLAYER_NAME.to_owned(),
-                    x: p.position.x,
-                    y: p.position.y,
-                    z: p.position.z,
-                    dimension: self.dim.id().to_owned(),
-                    game_mode: match self.mode {
-                        Mode::Survival => GameMode::Survival,
-                        Mode::Creative => GameMode::Creative,
-                        Mode::Adventure => GameMode::Adventure,
-                        Mode::Spectator => GameMode::Spectator,
-                    },
-                    health: p.health.health(),
-                });
-            }
-            let guests = host
-                .or(self.lan.as_ref())
-                .into_iter()
-                .flat_map(|h| &h.hub.guests);
-            out.extend(guests.filter(|g| g.placed).map(|g| ServerPlayer {
-                id: uuid_string(g.uuid),
-                name: g.name.clone(),
-                x: g.position[0],
-                y: g.position[1],
-                z: g.position[2],
-                dimension: g.dimension.clone(),
-                game_mode: mode(g.game_mode),
-                health: g.health,
-            }));
-            out
-        }
-
-        /// Whether what players do now reaches server mods: one is running
-        /// and this game simulates the world.
-        fn hears_players(&self) -> bool {
-            self.mods.server && self.remote.is_none()
-        }
-
-        /// The tick's end: joins and leaves, the tick's events, the tick hook.
-        pub(in crate::game) fn tick_server_mods(&mut self) {
-            if !self.options.execution_role.is_client() {
-                // A server has no frames to check its dev mods in.
-                self.reload_dev_mods();
-            }
-            self.send_server_mod_commands();
-            if !self.mods.server {
-                return;
-            }
-            let players = self.server_players(None);
-            let snapshot = self.mod_snapshot_with(players.clone());
-            self.mods.mods.set_snapshot(snapshot);
-            self.lend_world();
-            let before = std::mem::take(&mut self.mods.players);
-            for p in before
-                .iter()
-                .filter(|p| !players.iter().any(|q| q.id == p.id))
-            {
-                self.mods.mods.player_left(p);
-            }
-            for p in players
-                .iter()
-                .filter(|p| !before.iter().any(|q| q.id == p.id))
-            {
-                self.mods.mods.player_joined(p);
-            }
-            for event in std::mem::take(&mut self.mods.events) {
-                let who = |w: &Who| {
-                    let id = match w {
-                        Who::Local => uuid_string(self.player_uuid()),
-                        Who::Uuid(u) => uuid_string(*u),
-                        Who::Conn(c) => {
-                            let guests = self.lan.iter().flat_map(|h| &h.hub.guests);
-                            let g = guests.into_iter().find(|g| g.conn == *c);
-                            g.map_or_else(String::new, |g| uuid_string(g.uuid))
-                        }
-                    };
-                    players.iter().chain(&before).find(|p| p.id == id).cloned()
-                };
-                match event {
-                    ModEvent::Chat(w, text) => {
-                        if let Some(p) = who(&w) {
-                            self.mods.mods.player_chat(&p, &text);
-                        }
-                    }
-                    ModEvent::Block {
-                        who: w,
-                        pos,
-                        state,
-                        placed,
-                    } => {
-                        let Some(p) = who(&w) else { continue };
-                        let pos = BlockPos {
-                            x: pos[0],
-                            y: pos[1],
-                            z: pos[2],
-                        };
-                        if placed {
-                            self.mods.mods.block_placed(&p, pos, &state);
-                        } else {
-                            self.mods.mods.block_broken(&p, pos, &state);
-                        }
-                    }
-                }
-            }
-            self.mods.mods.server_tick(self.ticks);
-            self.return_world();
-            self.mods.players = players;
-            self.show_mod_output();
-            self.apply_mod_block_writes();
-        }
-
-        /// Players' command trees list the running server mods' commands
-        /// after vanilla's, whenever they change (or a hub opens).
-        fn send_server_mod_commands(&mut self) {
-            let key = self.mods.mods.generation();
-            let Some(host) = self.lan.as_mut() else {
-                return;
-            };
-            if host.hub.mod_commands_key() == Some(key) {
-                return;
-            }
-            let tree = command_tree(self.mods.mods.server_commands());
-            host.hub.set_mod_commands(key, tree);
-        }
-
-        /// Lends the levels' chunks to capability `world` for the calls up to
-        /// [`Game::return_world`], when a running server mod has it.
-        fn lend_world(&mut self) {
-            if !self.mods.world {
-                return;
-            }
-            let mut dims = vec![(self.dim.id(), std::mem::take(&mut self.world.chunks))];
-            for (dim, chunks) in self.levels.parked_chunks() {
-                dims.push((dim.id(), std::mem::take(chunks)));
-            }
-            let registry = self.pack.assets.registry;
-            let biomes = self.res.biomes().clone();
-            self.mods.mods.lend_world(Box::new(LentWorld {
-                registry,
-                biomes,
-                dims,
-            }));
-        }
-
-        /// Puts back the chunks [`Game::lend_world`] lent.
-        fn return_world(&mut self) {
-            let Some(view) = self.mods.mods.take_world() else {
-                return;
-            };
-            let view: Box<dyn std::any::Any> = view;
-            let Ok(lent) = view.downcast::<LentWorld>() else {
-                return;
-            };
-            let mut dims = lent.dims;
-            if let Some(i) = dims.iter().position(|(d, _)| *d == self.dim.id()) {
-                self.world.chunks = dims.swap_remove(i).1;
-            }
-            for (dim, chunks) in self.levels.parked_chunks() {
-                if let Some(i) = dims.iter().position(|(d, _)| *d == dim.id()) {
-                    *chunks = dims.swap_remove(i).1;
-                }
-            }
-        }
-
-        /// Makes the blocks server mods set in the level in place, in order,
-        /// as `/setblock` does. Those of other dimensions wait for their level.
-        pub(in crate::game) fn apply_mod_block_writes(&mut self) {
-            if self.mods.block_writes.is_empty() {
-                return;
-            }
-            let dim = self.dim.id();
-            let (now, later): (Vec<_>, Vec<_>) = std::mem::take(&mut self.mods.block_writes)
-                .into_iter()
-                .partition(|(d, _)| d == dim);
-            self.mods.block_writes = later;
-            let registry = self.pack.assets.registry;
-            for (_, b) in now {
-                let state = match crate::game::render_control::parse_state(registry, &b.state) {
-                    Ok(state) => state,
-                    Err(e) => {
-                        log::warn!("Horizon: a server mod set {}: {e}", b.state);
-                        continue;
-                    }
-                };
-                if let Err(e) = self.place_state([b.x, b.y, b.z], state, false) {
-                    log::debug!(
-                        "Horizon: a server mod's block at {} {} {}: {e:?}",
-                        b.x,
-                        b.y,
-                        b.z
-                    );
-                }
-            }
-        }
-
-        /// A player broke (or placed) `state` at `pos`: the player acting now.
-        pub(in crate::game) fn mod_block_event(
-            &mut self,
-            pos: [i32; 3],
-            state: BlockStateId,
-            placed: bool,
-        ) {
-            if !self.hears_players() {
-                return;
-            }
-            let who = self.lan_acting.map_or(Who::Local, Who::Conn);
-            let state = self.state_string(state);
-            self.mods.events.push(ModEvent::Block {
-                who,
-                pos,
-                state,
-                placed,
-            });
-        }
-
-        /// A chat message a player sent.
-        pub(in crate::game) fn mod_player_chat(&mut self, who: Who, text: &str) {
-            if self.hears_players() {
-                self.mods.events.push(ModEvent::Chat(who, text.to_owned()));
-            }
-        }
-
-        /// `/line` typed by the window's own player in-frame: true when a
-        /// server mod owns it.
-        pub(in crate::game) fn local_server_mod_command(&mut self, line: &str) -> bool {
-            if !self.hears_players() {
-                return false;
-            }
-            let players = self.server_players(None);
-            let Some(me) = players.first().cloned() else {
-                return false;
-            };
-            let snapshot = self.mod_snapshot_with(players);
-            self.mods.mods.set_snapshot(snapshot);
-            self.lend_world();
-            let owned = self.mods.mods.server_command(&me, line);
-            self.return_world();
-            self.show_mod_output();
-            self.apply_mod_block_writes();
-            owned
-        }
-
-        /// `/line` typed by a connection's player: true when a server mod
-        /// owns it, whatever the player's permission level.
-        pub(in crate::game) fn guest_server_mod_command(
-            &mut self,
-            host: &mut LanHost,
-            conn: u32,
-            line: &str,
-        ) -> bool {
-            if !self.hears_players() {
-                return false;
-            }
-            let Some(g) = host.hub.guest(conn) else {
-                return false;
-            };
-            let id = uuid_string(g.uuid);
-            let players = self.server_players(Some(host));
-            let Some(me) = players.iter().find(|p| p.id == id).cloned() else {
-                return false;
-            };
-            let snapshot = self.mod_snapshot_with(players);
-            self.mods.mods.set_snapshot(snapshot);
-            self.lend_world();
-            let owned = self.mods.mods.server_command(&me, line);
-            self.return_world();
-            if !owned {
-                return false;
-            }
-            self.route_mod_output(Some(host));
-            self.apply_mod_block_writes();
-            true
-        }
-
-        /// Sends a server mod's line to the player with this id: the
-        /// window's own chat for the local player, a system message for a
-        /// connection's. `host` is the hub when it is out of `self.lan`.
-        pub(in crate::game) fn tell_server_player(
-            &mut self,
-            host: Option<&mut LanHost>,
-            id: &str,
-            line: Text,
-        ) {
-            let local = self.options.execution_role.is_client()
-                && self.remote.is_none()
-                && self.player.is_some();
-            if local && uuid_string(self.player_uuid()) == id {
-                self.add_mod_chat_line(line);
-                return;
-            }
-            let Some(host) = host.or(self.lan.as_mut()) else {
-                return;
-            };
-            let to = host
-                .hub
-                .guests
-                .iter()
-                .find(|g| g.placed && uuid_string(g.uuid) == id);
-            if let Some(conn) = to.map(|g| g.conn) {
-                host.hub.send_to(
-                    conn,
-                    &C::SystemChat(play::SystemChat {
-                        content: component_nbt(&line.component()),
-                        overlay: false,
-                    }),
-                );
-            }
-        }
-
-        /// Routes a server mod's output: `Tell` and `Reply` to their player,
-        /// `Broadcast` to everyone and the log.
-        pub(in crate::game) fn route_server_output(
-            &mut self,
-            mut host: Option<&mut LanHost>,
-            output: Output,
-        ) {
-            let named = |name: &str, text: String| {
-                let mut line = Text::literal(format!("[{name}] ")).with_color(text::GRAY);
-                line.push(Text::literal(text));
-                line
-            };
-            match output {
-                Output::Tell { name, player, text } => {
-                    self.tell_server_player(host, &player, named(&name, text));
-                }
-                Output::Reply {
-                    player,
-                    text,
-                    error,
-                } => {
-                    let line = Text::literal(text);
-                    let line = if error {
-                        line.with_color(text::RED)
-                    } else {
-                        line
-                    };
-                    self.tell_server_player(host, &player, line);
-                }
-                Output::Broadcast { name, text } => {
-                    let plain = format!("[{name}] {text}");
-                    if self.options.dedicated.is_some() {
-                        super::super::dedicated::log("INFO", &plain);
-                    } else {
-                        log::info!("{plain}");
-                    }
-                    for p in self.server_players(host.as_deref()) {
-                        let line = named(&name, text.clone());
-                        self.tell_server_player(host.as_deref_mut(), &p.id, line);
-                    }
-                }
-                Output::SetBlocks {
-                    name,
-                    dimension,
-                    blocks,
-                } => {
-                    let queued = &mut self.mods.block_writes;
-                    queued.extend(blocks.into_iter().map(|b| (dimension.clone(), b)));
-                    if queued.len() > MAX_QUEUED_WRITES {
-                        let over = queued.len() - MAX_QUEUED_WRITES;
-                        queued.drain(..over);
-                        log::warn!(
-                            "Horizon: mod {name} set more blocks than wait for their level: {over} dropped"
-                        );
-                    }
-                }
-                _ => {}
-            }
-        }
-    }
-}

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

@@ -6,6 +6,7 @@
 
 use horizon_client::camera::CameraFluid;
 use horizon_client::gfx::pack_uniforms::PackInputs;
+use horizon_client::text::Text;
 use horizon_shaders::{BlockIds, Macros, Pack, Properties, dimension_folder, load_post};
 
 use super::{Dim, Game};
@@ -64,79 +65,87 @@ impl Game<'_> {
         {
             let name = name.as_str();
             let started = std::time::Instant::now();
-            match Pack::open(&path) {
-                Ok(pack) => {
-                    let macros = Macros::standard();
-                    let text = pack.read_text("shaders.properties").unwrap_or_default();
-                    let properties = Properties::parse(&text, &macros);
-                    for note in &properties.notes {
-                        log::warn!(
-                            "shader pack {name}: shaders.properties:{}: {}",
-                            note.line,
-                            note.message
-                        );
-                    }
-                    let folder = dimension_folder(&pack, dimension);
-                    let inputs = renderer.pack_inputs();
-                    let mut post = load_post(&pack, &folder, &properties, &macros, &inputs);
-                    let biomes = self.res.biomes();
-                    let names: Vec<&str> = biomes.list.iter().map(|b| b.name.as_str()).collect();
-                    post.custom.set_biomes(&names);
-                    let text = pack.read_text("block.properties").unwrap_or_default();
-                    let ids = BlockIds::parse(&Properties::parse(&text, &macros));
-                    for note in &ids.notes {
-                        log::warn!("shader pack {name}: block.properties: {note}");
-                    }
-                    let text = pack.read_text("entity.properties");
-                    let entities = BlockIds::parse_kind(
-                        &Properties::parse(text.as_deref().unwrap_or_default(), &macros),
-                        "entity",
-                    );
-                    let text = pack.read_text("item.properties");
-                    let items = BlockIds::parse_kind(
-                        &Properties::parse(text.as_deref().unwrap_or_default(), &macros),
-                        "item",
-                    );
-                    self.pack_ids = Some(PackIds {
-                        items: items.plain(),
-                        missing_item: if text.is_some() { -1 } else { 0 },
-                        // OQ-21: on unless the pack turns it off.
-                        old_hand_light: properties
-                            .get("oldHandLight")
-                            .is_none_or(|v| v.trim() != "false"),
-                        entities: entities.plain(),
-                        missing_entity: if text.is_some() { 65535 } else { 0 },
-                        missing_block: if ids.is_empty() { 0 } else { 65535 },
-                        blocks: ids.clone(),
-                        block_states: RefCell::default(),
-                    });
-                    let started_ids = std::time::Instant::now();
-                    let table = block_id_table(&self.pack, &ids);
-                    log::info!(
-                        "shader pack {name}: mc_Entity for {} of {} block sprites in {} ms",
-                        table.chunks(2).filter(|p| p[0] != -1).count(),
-                        table.len() / 2,
-                        started_ids.elapsed().as_millis()
-                    );
-                    if let Some((programs, notes)) =
-                        renderer.set_shader_pack(dimension, Some(post), &table)
-                    {
-                        for note in notes {
-                            log::warn!("shader pack {name}: {note}");
+            // A pack is not the game's own code: one that makes the shader compiler (or our
+            // translation of it) panic is turned off instead of crashing every world load (#3525).
+            let loaded = horizon_client::crash::contain(|| {
+                match Pack::open(&path) {
+                    Ok(pack) => {
+                        let macros = Macros::standard();
+                        let text = pack.read_text("shaders.properties").unwrap_or_default();
+                        let properties = Properties::parse(&text, &macros);
+                        for note in &properties.notes {
+                            log::warn!(
+                                "shader pack {name}: shaders.properties:{}: {}",
+                                note.line,
+                                note.message
+                            );
                         }
-                        log::info!(
-                            "shader pack {name}: folder `{folder}`, {} programs ({}) in {} ms",
-                            programs.len(),
-                            programs.join(" "),
-                            started.elapsed().as_millis()
+                        let folder = dimension_folder(&pack, dimension);
+                        let inputs = renderer.pack_inputs();
+                        let mut post = load_post(&pack, &folder, &properties, &macros, &inputs);
+                        let biomes = self.res.biomes();
+                        let names: Vec<&str> =
+                            biomes.list.iter().map(|b| b.name.as_str()).collect();
+                        post.custom.set_biomes(&names);
+                        let text = pack.read_text("block.properties").unwrap_or_default();
+                        let ids = BlockIds::parse(&Properties::parse(&text, &macros));
+                        for note in &ids.notes {
+                            log::warn!("shader pack {name}: block.properties: {note}");
+                        }
+                        let text = pack.read_text("entity.properties");
+                        let entities = BlockIds::parse_kind(
+                            &Properties::parse(text.as_deref().unwrap_or_default(), &macros),
+                            "entity",
                         );
+                        let text = pack.read_text("item.properties");
+                        let items = BlockIds::parse_kind(
+                            &Properties::parse(text.as_deref().unwrap_or_default(), &macros),
+                            "item",
+                        );
+                        self.pack_ids = Some(PackIds {
+                            items: items.plain(),
+                            missing_item: if text.is_some() { -1 } else { 0 },
+                            // OQ-21: on unless the pack turns it off.
+                            old_hand_light: properties
+                                .get("oldHandLight")
+                                .is_none_or(|v| v.trim() != "false"),
+                            entities: entities.plain(),
+                            missing_entity: if text.is_some() { 65535 } else { 0 },
+                            missing_block: if ids.is_empty() { 0 } else { 65535 },
+                            blocks: ids.clone(),
+                            block_states: RefCell::default(),
+                        });
+                        let started_ids = std::time::Instant::now();
+                        let table = block_id_table(&self.pack, &ids);
+                        log::info!(
+                            "shader pack {name}: mc_Entity for {} of {} block sprites in {} ms",
+                            table.chunks(2).filter(|p| p[0] != -1).count(),
+                            table.len() / 2,
+                            started_ids.elapsed().as_millis()
+                        );
+                        if let Some((programs, notes)) =
+                            renderer.set_shader_pack(dimension, Some(post), &table)
+                        {
+                            for note in notes {
+                                log::warn!("shader pack {name}: {note}");
+                            }
+                            log::info!(
+                                "shader pack {name}: folder `{folder}`, {} programs ({}) in {} ms",
+                                programs.len(),
+                                programs.join(" "),
+                                started.elapsed().as_millis()
+                            );
+                        }
+                    }
+                    Err(e) => {
+                        self.pack_ids = None;
+                        log::warn!("shader pack {name}: {e}");
+                        renderer.set_shader_pack(dimension, None, &[]);
                     }
                 }
-                Err(e) => {
-                    self.pack_ids = None;
-                    log::warn!("shader pack {name}: {e}");
-                    renderer.set_shader_pack(dimension, None, &[]);
-                }
+            });
+            if let Err(panic) = loaded {
+                self.shader_pack_failed(name, dimension, &panic);
             }
         }
         let lerp = |(old, new): (f32, f32)| old + (new - old) * partial;
@@ -175,6 +184,25 @@ impl Game<'_> {
         }
     }
 
+    /// Turns off the pack `name` after loading it panicked: nothing runs in its place, it is no
+    /// longer the picked pack (so the next start does not load it again), and the chat says so.
+    fn shader_pack_failed(&mut self, name: &str, dimension: i32, error: &str) {
+        log::error!("shader pack {name}: turned off: {error}");
+        self.pack_ids = None;
+        if let Some(renderer) = &mut self.renderer {
+            // Marks this dimension as loaded, without a pack, so it is not tried again.
+            renderer.set_shader_pack(dimension, None, &[]);
+        }
+        if self.settings.horizon.shader_pack == name {
+            self.settings.horizon.shader_pack.clear();
+            self.settings.save(&Self::options_path());
+        }
+        self.system_message(Text::colored(
+            format!("Shader pack {name} could not be loaded and was turned off"),
+            0xFF5555,
+        ));
+    }
+
     /// `heldItemId(2)` and `heldBlockLightValue(2)`: main hand, then off hand (5.2, 5.3).
     fn held_for_pack(&mut self) -> ([i32; 2], [i32; 2]) {
         if self.pack_ids.is_none() {

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

@@ -407,9 +407,40 @@ impl Game<'_> {
         }
         // sendBlockUpdated(3) and the player's block_change game event.
         self.spawner_block_updated(key);
+        self.update_spawner_display(key);
         self.post_block_game_event("minecraft:block_change", pos, Some(Who::Player), None);
         Some(true)
     }
+    /// Ticks spawners and trial spawners near the player on a remote client (`tick_remote`).
+    pub(super) fn tick_remote_spawners(&mut self) {
+        let Some(p) = self.player.as_ref() else {
+            return;
+        };
+        let center = [
+            p.position.x.floor() as i32,
+            p.position.y.floor() as i32,
+            p.position.z.floor() as i32,
+        ];
+        let mut keys = Vec::new();
+        let mut trial_keys = Vec::new();
+        for (&pos, be) in &self.world.block_entities {
+            let d = (pos.0 - center[0])
+                .abs()
+                .max((pos.1 - center[1]).abs())
+                .max((pos.2 - center[2]).abs());
+            if d <= 64 {
+                match be {
+                    BlockEntity::Spawner(_) => keys.push(pos),
+                    BlockEntity::TrialSpawner(_) => trial_keys.push(pos),
+                    _ => {}
+                }
+            }
+        }
+        self.client_tick_spawners(&keys);
+        for key in trial_keys {
+            self.client_tick_trial_spawner(key);
+        }
+    }
     /// `SpawnerRenderer` and `TrialSpawnerRenderer`: the next mob of every
     /// spawner near the camera, small and turning.
     pub(super) fn spawner_geometry(

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

@@ -76,6 +76,7 @@ impl StartupMenu {
                 &self.root,
             );
             title.last_server = settings.file.string("lastServer");
+            title.skip_multiplayer_warning = settings.file.bool("skipMultiplayerWarning");
             self.title = Some(title);
         }
     }
@@ -204,6 +205,15 @@ impl StartupMenu {
     }
 }
 
+/// A panic's message: its `&str` or `String` payload.
+fn panic_text(payload: &(dyn std::any::Any + Send)) -> &str {
+    payload
+        .downcast_ref::<&str>()
+        .copied()
+        .or_else(|| payload.downcast_ref::<String>().map(String::as_str))
+        .unwrap_or("Box<dyn Any>")
+}
+
 /// Each generation has its own channel and progress. Pack changes wait for the
 /// old tail before starting another generation, including cache/global writes.
 pub(super) fn spawn_loader(
@@ -251,20 +261,27 @@ pub(super) fn spawn_loader(
 
 impl Loading {
     pub(super) fn poll_menu_resources(&mut self) -> Result<()> {
-        if self.loaded.is_none() {
+        // Once `Done` arrived the generation is over: the caller may have taken
+        // its result, and the finished loader's channel is closed.
+        if self.loaded.is_none() && !self.delivered {
             loop {
                 match self.receiver.try_recv() {
                     Ok(LoaderMsg::Ui(gui, root)) => self.set_ui(gui, root),
                     Ok(LoaderMsg::Done(result)) => {
                         self.loaded = Some(result);
+                        self.delivered = true;
                         break;
                     }
                     Err(TryRecvError::Empty) => break,
                     Err(TryRecvError::Disconnected) => {
-                        if let Some(handle) = self.handle.take() {
-                            let _ = handle.join();
-                        }
-                        return Err("resource loader stopped before finishing".into());
+                        // The loader sends `Done` before it returns: it panicked.
+                        let reason = match self.handle.take().map(JoinHandle::join) {
+                            Some(Err(payload)) => format!(": {}", panic_text(payload.as_ref())),
+                            _ => String::new(),
+                        };
+                        return Err(
+                            format!("resource loader stopped before finishing{reason}").into()
+                        );
                     }
                 }
             }
@@ -304,12 +321,11 @@ impl Loading {
     }
 
     fn save_menu_address(&mut self) {
-        if self
-            .menu
-            .title
-            .as_ref()
-            .is_some_and(|title| title.last_server != self.settings.file.string("lastServer"))
-        {
+        if self.menu.title.as_ref().is_some_and(|title| {
+            title.last_server != self.settings.file.string("lastServer")
+                || title.skip_multiplayer_warning
+                    != self.settings.file.bool("skipMultiplayerWarning")
+        }) {
             self.save_menu_settings();
         }
     }
@@ -320,6 +336,10 @@ impl Loading {
                 "lastServer",
                 horizon_client::options_file::V::Str(title.last_server.clone()),
             );
+            self.settings.file.set(
+                "skipMultiplayerWarning",
+                horizon_client::options_file::V::Bool(title.skip_multiplayer_warning),
+            );
         }
         self.settings.save(&Game::options_path());
     }
@@ -405,7 +425,7 @@ impl Loading {
                     }
                 }
                 // Mods' settings pages open only in a running game.
-                Event::ModSettings(_) | Event::NativeSettings(_) | Event::NativeButton(..) => {}
+                Event::NativeSettings(_) | Event::NativeButton(..) => {}
                 // The startup menu runs before the game opens a control socket.
                 Event::ButtonClick | Event::CopyAgentDetails => {}
             }
@@ -678,8 +698,11 @@ impl Loading {
             }
         }
         self.loaded = None;
+        self.delivered = false;
         if let Some(handle) = self.handle.take() {
-            handle.join().map_err(|_| "resource loader panicked")?;
+            handle.join().map_err(|payload| {
+                format!("resource loader panicked: {}", panic_text(payload.as_ref()))
+            })?;
         }
         self.progress = Progress::new();
         let options = self.options.as_ref().ok_or("loading already finished")?;
@@ -726,6 +749,7 @@ mod tests {
             progress: Progress::new(),
             receiver,
             loaded: None,
+            delivered: false,
             handle: None,
             shown: false,
             menu: StartupMenu::default(),
@@ -803,6 +827,47 @@ mod tests {
         assert!(menu.pending.take().is_none(), "an entry is consumed once");
     }
 
+    #[test]
+    fn a_failed_generation_keeps_its_error_after_the_loader_ends() {
+        let (sender, receiver) = std::sync::mpsc::channel();
+        let worker = std::thread::spawn(move || {
+            sender
+                .send(LoaderMsg::Done(Err("missing facts.json".into())))
+                .unwrap();
+        });
+        let mut loading = loading(receiver);
+        loading.handle = Some(worker);
+        while loading.loaded.is_none() {
+            loading.poll_menu_resources().unwrap();
+        }
+        // App::about_to_wait takes the result to report it; the loop may poll
+        // once more before it exits, with the loader gone.
+        assert!(matches!(loading.loaded.take(), Some(Err(e)) if e == "missing facts.json"));
+        while !loading.handle.as_ref().is_none_or(JoinHandle::is_finished) {
+            std::thread::yield_now();
+        }
+        loading.poll_menu_resources().unwrap();
+        assert!(loading.loaded.is_none());
+    }
+
+    #[test]
+    fn a_panicking_loader_reports_its_panic() {
+        let (sender, receiver) = std::sync::mpsc::channel::<LoaderMsg>();
+        let worker = std::thread::spawn(move || {
+            let _sender = sender;
+            panic!("atlas has no fonts");
+        });
+        while !worker.is_finished() {
+            std::thread::yield_now();
+        }
+        let mut loading = loading(receiver);
+        loading.handle = Some(worker);
+        assert_eq!(
+            loading.poll_menu_resources().unwrap_err().to_string(),
+            "resource loader stopped before finishing: atlas has no fonts"
+        );
+    }
+
     #[test]
     fn disconnected_core_worker_is_reported_instead_of_waiting_forever() {
         let (sender, receiver) = std::sync::mpsc::channel();

crates/horizon-client/src/item_render/special.rs

@@ -556,11 +556,14 @@ pub(super) fn submit(
             } else {
                 "entity/shield/shield_base_nopattern"
             };
-            let foil = if has_foil && !has_patterns {
-                Foil::Standard
-            } else {
-                Foil::None
-            };
+            // Without patterns: `entitySolidGlint`. With them, vanilla draws
+            // `patternedShieldGlint` last, the glint alone over the finished
+            // plate. A foil quad here is its texture with the glint over it
+            // (the GUI adds the glint masked by the layer's alpha, the world
+            // shader composites it), so every layer carries the foil: each
+            // pixel ends with the glint once, over the layers below it.
+            // Redrawing the base with the foil would cover the patterns.
+            let foil = if has_foil { Foil::Standard } else { Foil::None };
             part("shield", &none, base, white, foil);
             if has_patterns {
                 part(
@@ -568,17 +571,13 @@ pub(super) fn submit(
                     &none,
                     "entity/shield/base",
                     dye(base_color.unwrap_or("white")),
-                    Foil::None,
+                    foil,
                 );
                 for (pattern, color) in patterns.into_iter().take(16) {
                     if let Some(t) = pattern_texture(host, false, &pattern) {
-                        part("shield", &none, &t, dye(&color), Foil::None);
+                        part("shield", &none, &t, dye(&color), foil);
                     }
                 }
-                if has_foil {
-                    // `patternedShieldGlint`: the glint alone over the model.
-                    part("shield", &none, base, white, Foil::Standard);
-                }
             }
         }
         SpecialKind::DecoratedPot => {
@@ -688,6 +687,105 @@ mod tests {
             );
         }
     }
+    /// `ShieldSpecialRenderer.submit` of an enchanted shield with a banner:
+    /// the glint goes over the patterns, and nothing covers them after.
+    #[test]
+    fn an_enchanted_banner_shield_keeps_its_patterns_under_the_glint() {
+        let root =
+            std::env::temp_dir().join(format!("horizon-shield-glint-{}", std::process::id()));
+        std::fs::create_dir_all(&root).unwrap();
+        std::fs::write(root.join("items.json"), "{}").unwrap();
+        std::fs::write(
+            root.join("entity-models.json"),
+            serde_json::json!({"minecraft:shield#main": {
+                "pose": [0, 0, 0, 0, 0, 0, 1, 1, 1],
+                "polygons": [[[0, 0, 0, 0, 0], [1, 0, 0, 1, 0],
+                              [1, 1, 0, 1, 1], [0, 1, 0, 0, 1]]],
+                "children": {}
+            }})
+            .to_string(),
+        )
+        .unwrap();
+        let library = crate::model_library::ParsedModels::default().into_item_library();
+        let renderer = ItemRenderer::load_with_library(&root, library).unwrap();
+        let _ = std::fs::remove_dir_all(&root);
+        let textures = [
+            "entity/shield/shield_base",
+            "entity/shield/shield_base_nopattern",
+            "entity/shield/base",
+            "entity/shield/stripe_bottom",
+        ];
+        // A sprite per texture, told apart by its u0.
+        let sprites: HashMap<String, Rect> = textures
+            .iter()
+            .enumerate()
+            .map(|(i, t)| {
+                let u0 = i as f32 / 8.0;
+                let rect = Rect {
+                    u0,
+                    v0: 0.0,
+                    u1: u0 + 0.1,
+                    v1: 0.1,
+                    w: 16,
+                    h: 16,
+                };
+                ((*t).to_owned(), rect)
+            })
+            .collect();
+        let drawn = |argument: Value, has_foil: bool| {
+            let mut quads: Vec<ItemQuad> = Vec::new();
+            submit(
+                &renderer,
+                &SpecialModel {
+                    kind: SpecialKind::Shield,
+                },
+                &argument,
+                has_foil,
+                Mat4::IDENTITY,
+                &sprites,
+                &super::super::NoHost,
+                &mut quads,
+            );
+            quads
+                .iter()
+                .map(|q| {
+                    let texture = textures
+                        .iter()
+                        .find(|t| sprites[**t].u0 == q.uv[0][0].min(q.uv[1][0]))
+                        .unwrap();
+                    (*texture, q.foil)
+                })
+                .collect::<Vec<_>>()
+        };
+        let banner = serde_json::json!({
+            "minecraft:base_color": "red",
+            "minecraft:banner_patterns": [{
+                "pattern": {"asset_id": "minecraft:stripe_bottom",
+                            "translation_key": "block.minecraft.banner.stripe_bottom"},
+                "color": "blue"
+            }]
+        });
+        assert_eq!(
+            drawn(banner.clone(), true),
+            [
+                ("entity/shield/shield_base", Foil::Standard),
+                ("entity/shield/base", Foil::Standard),
+                ("entity/shield/stripe_bottom", Foil::Standard),
+            ]
+        );
+        assert_eq!(
+            drawn(banner, false),
+            [
+                ("entity/shield/shield_base", Foil::None),
+                ("entity/shield/base", Foil::None),
+                ("entity/shield/stripe_bottom", Foil::None),
+            ]
+        );
+        assert_eq!(
+            drawn(Value::Null, true),
+            [("entity/shield/shield_base_nopattern", Foil::Standard)]
+        );
+    }
     /// `DecoratedPotRenderer` draws every part with `RenderTypes.entitySolid`,
     /// whose pipeline culls back faces: the pot's flat `top` and `bottom`
     /// planes would otherwise show both sides and z-fight in the hand too.

crates/horizon-client/src/lib.rs

@@ -14,8 +14,8 @@ pub use horizon_client_render::{
     mesher, minimap, mipmap, mod_list, model_library, models, options_file, options_fixes,
     options_ui, overlay, pack_screen, packs, par, particles, poi_sections, providers, screen_draw,
     screen_effects, sculk, settings, shader_pack_list, signs, skins, sound_engine, sound_events,
-    spans, sprites, streaming, tab_list, telemetry, testgen, title_edition, trims, ui, vault,
-    weather, widgets, world, worldborder, zip,
+    spans, split_layout, sprites, streaming, tab_list, telemetry, testgen, title_edition, trims,
+    ui, vault, weather, widgets, world, worldborder, zip,
 };
 pub mod attack_strength;
 pub mod attribute_updates;
@@ -74,7 +74,6 @@ pub mod merchant;
 pub mod mobs;
 pub mod mod_content;
 pub mod motion;
-pub mod moved_extras;
 pub mod multiplayer;
 pub mod music;
 pub mod net;

crates/horizon-client/src/mobs.rs

@@ -734,6 +734,9 @@ pub fn anger_left(anger_end: i64, game_time: i64) -> i32 {
 /// Species-specific persistent state (variants, colours, taming, ageing...).
 #[derive(Clone, Debug, Default)]
 pub struct Extra {
+    /// The local player's `minecraft:scale`, which scales the whole model
+    /// (`LivingEntityRenderState.scale`); 0 is the default, 1.
+    pub model_scale: f32,
     /// Players: crouching and riding (HumanoidModel's poses).
     pub crouching: bool,
     /// A player's or mannequin's synced pose (`Entity.DATA_POSE`), which
@@ -2446,6 +2449,7 @@ impl Mob {
         self.invisible || self.has_effect("minecraft:invisibility")
     }
     pub fn add_effect(&mut self, effect: &'static str, ticks: i32, amplifier: i32) {
+        let effect = horizon_client_core::potions::namespaced(effect);
         if let Some(e) = self.extra.effects.iter_mut().find(|e| e.0 == effect) {
             // MobEffectInstance.update: a stronger effect replaces with its
             // own duration, an equal one only extends it; a weaker one is

crates/horizon-client/src/mobs/ai.rs

@@ -475,7 +475,14 @@ pub fn tick(
     if m.species() == Species::ZombieVillager {
         // ZombieVillager.tick counts the cure down before super.tick, with
         // or without AI (NoAI only skips serverAiStep).
-        super::zombie_villager::step(m, &mut Cx { w, events });
+        super::zombie_villager::step(
+            m,
+            &mut Cx {
+                w,
+                lr: level_random,
+                events,
+            },
+        );
     }
     super::warden::pre_tick(m, w, events);
     if m.species() == Species::Strider {
@@ -1205,7 +1212,11 @@ fn server_ai_step(
     let mut targets = std::mem::take(&mut m.ai.targets);
     let mut goals = std::mem::take(&mut m.ai.goals);
     {
-        let mut cx = Cx { w, events };
+        let mut cx = Cx {
+            w,
+            lr: level_random,
+            events,
+        };
         if id_based % 2 != 0 && tick_count > 1 {
             targets.tick_running(m, &mut cx, false);
             goals.tick_running(m, &mut cx, false);
@@ -1246,7 +1257,11 @@ fn server_ai_step(
         super::animal_brain::tick(m, w, level_random, events);
     }
     {
-        let mut cx = Cx { w, events };
+        let mut cx = Cx {
+            w,
+            lr: level_random,
+            events,
+        };
         custom_server_ai_step(m, &mut cx);
     }
     if frozen {
@@ -2287,3 +2302,45 @@ mod frog_tests {
         );
     }
 }
+
+#[cfg(test)]
+mod poison_effect_tests {
+    use super::*;
+    use crate::mobs::MobTypes;
+    use std::sync::Arc;
+
+    #[test]
+    fn poison_effect_damages_living_mobs_but_not_undead() {
+        let root = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("../../.local/horizon-client")
+            .join(horizon_core::VANILLA_VERSION);
+        if !root.join("entity-types.json").exists() {
+            return;
+        }
+        let data = MobTypes::load(&root).unwrap();
+
+        // Pig is not undead: should take damage from poison.
+        let pig_kind = Arc::new(data.types.get("minecraft:pig").unwrap().clone());
+        let mut pig = Mob::new(1, pig_kind, Vec3::new(0.0, 4.0, 0.0), 0.0);
+        pig.add_effect("poison", 100, 0);
+        assert_eq!(pig.extra.effects[0].0, "minecraft:poison");
+        let initial_pig_health = pig.health;
+        tick_effects(&mut pig);
+        assert_eq!(
+            pig.health,
+            initial_pig_health - 1.0,
+            "living mob should take 1.0 damage from poison"
+        );
+
+        // Zombie is undead: immune to poison damage.
+        let zombie_kind = Arc::new(data.types.get("minecraft:zombie").unwrap().clone());
+        let mut zombie = Mob::new(2, zombie_kind, Vec3::new(0.0, 4.0, 0.0), 0.0);
+        zombie.add_effect("poison", 100, 0);
+        let initial_zombie_health = zombie.health;
+        tick_effects(&mut zombie);
+        assert_eq!(
+            zombie.health, initial_zombie_health,
+            "undead mobs are immune to poison"
+        );
+    }
+}

crates/horizon-client/src/mobs/animal_brain.rs

@@ -2396,6 +2396,7 @@ fn axolotl_action(m: &mut Mob, cx: &mut Bx, action: AxolotlAction, until: &mut i
                 target,
                 &mut super::goals::Cx {
                     w: cx.w,
+                    lr: cx.lr,
                     events: cx.events,
                 },
             );

crates/horizon-client/src/mobs/breeze.rs

@@ -103,8 +103,15 @@ pub(super) fn dangerous_block(name: &str) -> bool {
             | "minecraft:powder_snow"
     )
 }
-/// `LongJumpUtil.calculateJumpVectorForAngle` without the collision check.
-fn jump_vector(m: &Mob, target: Vec3, max_velocity: f32, angle: i32) -> Option<Vec3> {
+/// `LongJumpUtil.calculateJumpVectorForAngle`; with a world, the arc is
+/// checked for collisions (`checkCollision`).
+pub(super) fn jump_vector(
+    m: &Mob,
+    target: Vec3,
+    max_velocity: f32,
+    angle: i32,
+    collide: Option<&MobWorld>,
+) -> Option<Vec3> {
     let pos = m.position;
     let plane = Vec3::new(target.x - pos.x, 0.0, target.z - pos.z)
         .normalize()
@@ -130,8 +137,41 @@ fn jump_vector(m: &Mob, target: Vec3, max_velocity: f32, angle: i32) -> Option<V
         return None;
     }
     let (v0r, v0y) = (v0 * cos, v0 * sin);
+    if let Some(w) = collide {
+        // `ceil(r / v0r) * 2` points along the arc, each step clear of blocks.
+        let samples = (r / v0r).ceil() as i32 * 2;
+        let (sin_xz, cos_xz) = (jmath::sin(xz), jmath::cos(xz));
+        let mut ri = 0.0;
+        let mut previous: Option<Vec3> = None;
+        for _ in 0..samples - 1 {
+            ri += r / f64::from(samples);
+            let yi = sin / cos * ri - jmath::pow(ri, 2.0) * g / (2.0 * v0sq * jmath::pow(cos, 2.0));
+            let p = Vec3::new(pos.x + ri * cos_xz, pos.y + yi, pos.z + ri * sin_xz);
+            if previous.is_some_and(|q| !clear_transition(m, w, q, p)) {
+                return None;
+            }
+            previous = Some(p);
+        }
+    }
     Some(Vec3::new(v0r * jmath::cos(xz), v0y, v0r * jmath::sin(xz)).scale(f64::from(0.95_f32)))
 }
+/// `LongJumpUtil.isClearTransition`: the box fits at points no further apart
+/// than nine tenths of its smaller side.
+fn clear_transition(m: &Mob, w: &MobWorld, from: Vec3, to: Vec3) -> bool {
+    let d = to.subtract(from);
+    let min = f64::from(m.width().min(m.height()));
+    let checks = (d.length() / min).ceil() as i32;
+    let step = d.normalize().scale(min * f64::from(0.9_f32));
+    let mut p = from;
+    (0..checks).all(|i| {
+        p = if i == checks - 1 {
+            to
+        } else {
+            p.add_vector(step)
+        };
+        w.no_collision(m.bounds_at(p))
+    })
+}
 /// `LongJump.calculateOptimalJumpVector`: the allowed angles shuffled, the
 /// first that reaches the target.
 pub(super) fn optimal_jump_vector(m: &mut Mob, target: Vec3) -> Option<Vec3> {
@@ -143,7 +183,7 @@ pub(super) fn optimal_jump_vector(m: &mut Mob, target: Vec3) -> Option<Vec3> {
     let max = 0.058_333_334_f32 * m.attrs.follow_range as f32;
     let v = angles
         .iter()
-        .find_map(|&a| jump_vector(m, target, max, a))?;
+        .find_map(|&a| jump_vector(m, target, max, a, None))?;
     if m.has_effect("minecraft:jump_boost") {
         let amp = m
             .extra

crates/horizon-client/src/mobs/frog.rs

@@ -1,5 +1,5 @@
-//! Frogs (`Frog`, `FrogAi`): the `Croak` and `ShootTongue` behaviours as
-//! goals, the poses they set and the client's animation states.
+//! Frogs (`Frog`, `FrogAi`): the `Croak`, `ShootTongue` and long jump
+//! behaviours as goals, the poses they set and the client's animation states.
 //! AnimState states: jump, croak, tongue, swim idle.
 //!
 //! The brain's idle `RunOne` picks a croak three times as often as a stroll
@@ -13,7 +13,10 @@ use super::{
     },
     sync,
 };
-use horizon_core::{geometry::Vec3, random::RandomSource};
+use horizon_core::{
+    geometry::Vec3,
+    random::{LegacyRandom, RandomSource},
+};
 
 const JUMP: usize = 0;
 const CROAK: usize = 1;
@@ -30,6 +33,25 @@ const EATING_DISTANCE: f64 = 1.75;
 const DETECTION_DISTANCE: f64 = 10.0;
 const SCAN_RATE: i32 = 20;
 
+/// `FrogAi.TIME_BETWEEN_LONG_JUMPS` and the brain memory
+/// `LONG_JUMP_COOLDOWN_TICKS` (saved with the others, as `finalize` sets it).
+const TIME_BETWEEN_LONG_JUMPS: (i32, i32) = (100, 140);
+const LONG_JUMP_COOLDOWN: &str = "long_jump_cooldown";
+/// `FrogAi`'s `LongJumpToPreferredBlock`: `MAX_LONG_JUMP_WIDTH`,
+/// `MAX_LONG_JUMP_HEIGHT`, `MAX_JUMP_VELOCITY_MULTIPLIER` and the chance to
+/// look for a lily pad or big dripleaf first.
+const JUMP_WIDTH: i32 = 4;
+const JUMP_HEIGHT: i32 = 2;
+const JUMP_VELOCITY_MULTIPLIER: f32 = 3.571_428_8;
+const PREFERRED_BLOCKS_CHANCE: f32 = 0.5;
+/// `LongJumpToRandomPos.ALLOWED_ANGLES`, `FIND_JUMP_TRIES` and
+/// `PREPARE_JUMP_DURATION`.
+const ALLOWED_ANGLES: [i32; 4] = [65, 70, 75, 80];
+const FIND_JUMP_TRIES: i32 = 20;
+const PREPARE_JUMP_DURATION: i32 = 40;
+/// `LongJumpMidJump`'s duration (`TIME_OUT_DURATION`).
+const MID_JUMP_DURATION: i32 = 100;
+
 /// `ShootTongue.State`.
 #[derive(Clone, Copy, Debug, Default, PartialEq)]
 enum Phase {
@@ -56,6 +78,8 @@ pub struct State {
     eat_timer: i32,
     path_counter: i32,
     time: i32,
+    /// `LivingEntity.discardFriction`, set through the long jump.
+    pub discard_friction: bool,
 }
 
 pub fn register(m: &mut Mob) {
@@ -74,6 +98,7 @@ pub fn register(m: &mut Mob) {
     g.add(0, Float);
     g.add(1, Panic::new(1.25));
     g.add(2, ShootTongue);
+    g.add(3, LongJump::default());
     g.add(4, Croak);
     g.add(5, Stroll::avoiding_water(1.0).interval(1));
     g.add(6, LookAtPlayer::new(6.0));
@@ -119,6 +144,13 @@ fn can_eat(species: Species, size: i32) -> bool {
 
 /// `FrogAttackablesSensor` (every 20 ticks) and the memory timers.
 pub fn server_ai_step(m: &mut Mob, w: &MobWorld) {
+    // `CountDownCooldownTicks(LONG_JUMP_COOLDOWN_TICKS)`: one less each tick,
+    // erased the tick after it reaches 0.
+    match jump_cooldown(m) {
+        Some(t) if t > 0 => set_jump_cooldown(m, Some(t - 1)),
+        Some(_) => set_jump_cooldown(m, None),
+        None => {}
+    }
     let f = &mut m.extra.frog;
     f.unreachable.retain_mut(|(_, ttl)| {
         *ttl -= 1;
@@ -310,3 +342,366 @@ impl Goal for ShootTongue {
         }
     }
 }
+
+/// `LONG_JUMP_COOLDOWN_TICKS`.
+fn jump_cooldown(m: &Mob) -> Option<i64> {
+    m.extra
+        .memories
+        .iter()
+        .find(|x| x.0 == LONG_JUMP_COOLDOWN)
+        .map(|x| x.1)
+}
+fn set_jump_cooldown(m: &mut Mob, ticks: Option<i64>) {
+    let memories = &mut m.extra.memories;
+    let at = memories.iter().position(|x| x.0 == LONG_JUMP_COOLDOWN);
+    match (at, ticks) {
+        (Some(i), Some(t)) => memories[i].1 = t,
+        (Some(i), None) => {
+            memories.remove(i);
+        }
+        (None, Some(t)) => memories.push((LONG_JUMP_COOLDOWN, t, i64::MAX)),
+        (None, None) => {}
+    }
+}
+/// `TIME_BETWEEN_LONG_JUMPS.sample` from the level's random, divided as the
+/// caller asks.
+fn sample_cooldown(m: &mut Mob, lr: &mut LegacyRandom, div: i32) {
+    let (lo, hi) = TIME_BETWEEN_LONG_JUMPS;
+    let t = lr.next_int_between_inclusive(lo, hi).unwrap_or(lo) / div;
+    set_jump_cooldown(m, Some(i64::from(t)));
+}
+
+/// `FrogAi.isAcceptableLandingSpot`: no fluid in the target, below or above
+/// it; a lily pad or big dripleaf (`frog_prefer_jump_to`) or a trapdoor; else
+/// `LongJumpToRandomPos.defaultAcceptableLandingSpot`: a solid block below
+/// and a path type the frog walks without a malus.
+fn acceptable_landing(m: &Mob, w: &MobWorld, [x, y, z]: [i32; 3]) -> bool {
+    use super::path::PathType;
+    if (y - 1..=y + 1).any(|y| w.fluid(x, y, z) != crate::blocks::Fluid::None) {
+        return false;
+    }
+    let preferred = |y| w.has_tag("minecraft:frog_prefer_jump_to", w.block_name(x, y, z));
+    if preferred(y) || preferred(y - 1) {
+        return true;
+    }
+    let here = w.path_type_static(x, y, z);
+    if here == PathType::Trapdoor
+        || w.facts.is_air(w.world.block(x, y, z))
+            && w.path_type_static(x, y - 1, z) == PathType::Trapdoor
+    {
+        return true;
+    }
+    w.facts.get(w.world.block(x, y - 1, z)).solid_render && m.malus(here) == 0.0
+}
+
+/// `LongJumpToRandomPos.PossibleJump`: a block and its weight.
+type Candidate = ([i32; 3], i32);
+
+/// `FrogAi`'s long jump activity: `LongJumpToPreferredBlock` looks for a spot
+/// it cannot walk to, faces it for 40 ticks and leaps; `LongJumpMidJump`
+/// holds the pose until it lands. One goal here, like the brain activity
+/// that keeps the idle croak and stroll from starting meanwhile.
+#[derive(Clone, Debug, Default)]
+struct LongJump {
+    candidates: Vec<Candidate>,
+    not_preferred: Vec<Candidate>,
+    wanting_preferred: bool,
+    initial: Option<Vec3>,
+    chosen: Option<Vec3>,
+    /// The chosen spot, looked at while preparing.
+    look: [f64; 3],
+    tries: i32,
+    /// Ticks since the jump was chosen.
+    prepare: i32,
+    /// `LONG_JUMP_MID_JUMP`, and the ticks `LongJumpMidJump` has run.
+    mid_jump: bool,
+    in_air: Option<i32>,
+}
+impl LongJump {
+    /// `WeightedRandom.getRandomItem` with the level's random over the
+    /// candidates, removed once drawn.
+    fn draw(&mut self, lr: &mut LegacyRandom) -> Option<Candidate> {
+        let total: i32 = self.candidates.iter().map(|c| c.1).sum();
+        if total == 0 {
+            return None;
+        }
+        let mut pick = lr.next_int_bound(total).unwrap_or(0);
+        let i = self.candidates.iter().position(|c| {
+            pick -= c.1;
+            pick < 0
+        })?;
+        Some(self.candidates.remove(i))
+    }
+    /// `LongJumpToPreferredBlock.getJumpCandidate`: while it wants them, the
+    /// first drawn spot over a preferred block, else the first one passed over.
+    fn candidate(&mut self, w: &MobWorld, lr: &mut LegacyRandom) -> Option<Candidate> {
+        if !self.wanting_preferred {
+            return self.draw(lr);
+        }
+        while !self.candidates.is_empty() {
+            if let Some(c) = self.draw(lr) {
+                let [x, y, z] = c.0;
+                if w.has_tag("minecraft:frog_prefer_jump_to", w.block_name(x, y - 1, z)) {
+                    return Some(c);
+                }
+                self.not_preferred.push(c);
+            }
+        }
+        (!self.not_preferred.is_empty()).then(|| self.not_preferred.remove(0))
+    }
+    /// `LongJumpToRandomPos.pickCandidate`: the first acceptable spot it can
+    /// reach in an arc but not by an 8 block path.
+    fn pick(&mut self, m: &mut Mob, w: &MobWorld, lr: &mut LegacyRandom) {
+        while !self.candidates.is_empty() {
+            let Some((target, _)) = self.candidate(w, lr) else {
+                continue;
+            };
+            let here = [m.position.x.floor() as i32, m.position.z.floor() as i32];
+            if here == [target[0], target[2]] || !acceptable_landing(m, w, target) {
+                continue;
+            }
+            let centre = Vec3::new(
+                f64::from(target[0]) + 0.5,
+                f64::from(target[1]) + 0.5,
+                f64::from(target[2]) + 0.5,
+            );
+            let Some(v) = optimal_jump_vector(m, w, centre) else {
+                continue;
+            };
+            self.look = [centre.x, centre.y, centre.z];
+            let walkable = m
+                .create_path_raw(w, &[target], 0, 8.0)
+                .is_some_and(|p| p.reached);
+            if !walkable {
+                self.chosen = Some(v);
+                self.prepare = 0;
+                return;
+            }
+        }
+    }
+    /// `LongJumpMidJump.stop`, or the end of a search.
+    fn end(&mut self, m: &mut Mob, cx: &mut Cx) {
+        if self.mid_jump {
+            if m.on_ground {
+                m.velocity = m.velocity.multiply(Vec3::new(0.1, 1.0, 0.1));
+                let at = [m.position.x, m.position.y, m.position.z];
+                cx.events
+                    .push(MobEvent::Sound("entity.frog.step", at, 2.0, 1.0));
+            }
+            set_pose(m, sync::STANDING);
+            sample_cooldown(m, cx.lr, 1);
+        }
+        m.extra.frog.discard_friction = false;
+        *self = Self::default();
+    }
+}
+/// `LongJumpToRandomPos.start`'s candidates: every block of the box but the
+/// frog's own, weighted by the squared distance, in `betweenClosed` order.
+fn candidates([x, y, z]: [i32; 3]) -> Vec<Candidate> {
+    let mut out = Vec::new();
+    for dz in -JUMP_WIDTH..=JUMP_WIDTH {
+        for dy in -JUMP_HEIGHT..=JUMP_HEIGHT {
+            for dx in -JUMP_WIDTH..=JUMP_WIDTH {
+                if (dx, dy, dz) != (0, 0, 0) {
+                    out.push(([x + dx, y + dy, z + dz], dx * dx + dy * dy + dz * dz));
+                }
+            }
+        }
+    }
+    out
+}
+/// `LongJumpToRandomPos.calculateOptimalJumpVector`: the angles shuffled, the
+/// first arc that reaches the target clear of blocks. `Collections.shuffle`
+/// without a random draws from an unseeded one, not the mob's or the level's.
+fn optimal_jump_vector(m: &Mob, w: &MobWorld, target: Vec3) -> Option<Vec3> {
+    let mut random = crate::sound_engine::SoundEngine::unseeded();
+    let mut angles = ALLOWED_ANGLES;
+    for i in (2..=angles.len()).rev() {
+        let j = random.next_int_bound(i as i32).unwrap_or(0) as usize;
+        angles.swap(i - 1, j);
+    }
+    let max = (m.attrs.jump_strength * f64::from(JUMP_VELOCITY_MULTIPLIER)) as f32;
+    angles
+        .iter()
+        .find_map(|&a| super::breeze::jump_vector(m, target, max, a, Some(w)))
+}
+impl Goal for LongJump {
+    goal_clone!();
+    fn flags(&self) -> u8 {
+        MOVE | LOOK
+    }
+    fn interruptable(&self) -> bool {
+        !self.mid_jump
+    }
+    fn every_tick(&self) -> bool {
+        true
+    }
+    fn can_use(&mut self, m: &mut Mob, cx: &mut Cx) -> bool {
+        // The activity: no cooldown and out of water. FrogAi.initJumpActivity
+        // also wants TEMPTING_PLAYER and BREED_TARGET absent, and the
+        // LAY_SPAWN activity (IS_PREGNANT) goes before LONG_JUMP.
+        // TODO: gate on them once frogs follow frog_food, breed and lay
+        // frogspawn here; none of the three exists for frogs yet.
+        if jump_cooldown(m).is_some() || m.fluids.in_water {
+            return false;
+        }
+        // checkExtraStartConditions: on the ground, not in lava or on honey.
+        let (x, y, z) = (
+            m.position.x.floor() as i32,
+            m.position.y.floor() as i32,
+            m.position.z.floor() as i32,
+        );
+        let can =
+            m.on_ground && !m.fluids.in_lava && cx.w.block_name(x, y, z) != "minecraft:honey_block";
+        if !can {
+            sample_cooldown(m, cx.lr, 2);
+        }
+        can
+    }
+    fn start(&mut self, m: &mut Mob, _cx: &mut Cx) {
+        // LongJumpToRandomPos.start.
+        let (x, y, z) = (
+            m.position.x.floor() as i32,
+            m.position.y.floor() as i32,
+            m.position.z.floor() as i32,
+        );
+        *self = Self {
+            candidates: candidates([x, y, z]),
+            tries: FIND_JUMP_TRIES,
+            initial: Some(m.position),
+            ..Self::default()
+        };
+        // LongJumpToPreferredBlock.start.
+        self.wanting_preferred = m.random.next_float() < PREFERRED_BLOCKS_CHANCE;
+    }
+    fn can_continue(&mut self, m: &mut Mob, cx: &mut Cx) -> bool {
+        if self.mid_jump {
+            // LongJumpMidJump starts the tick after the leap and runs until
+            // the frog is on the ground again, for 100 ticks at most; water
+            // switches the brain to the swim activity, which stops it too.
+            match self.in_air {
+                None => {
+                    self.in_air = Some(0);
+                    m.extra.frog.discard_friction = true;
+                    set_pose(m, sync::LONG_JUMPING);
+                }
+                Some(t) => self.in_air = Some(t + 1),
+            }
+            return !m.on_ground
+                && !m.fluids.in_water
+                && self.in_air.is_some_and(|t| t <= MID_JUMP_DURATION);
+        }
+        let valid = self.initial == Some(m.position)
+            && self.tries > 0
+            && !m.fluids.in_water
+            && !(self.chosen.is_none() && self.candidates.is_empty());
+        if !valid {
+            sample_cooldown(m, cx.lr, 2);
+        }
+        valid
+    }
+    fn stop(&mut self, m: &mut Mob, cx: &mut Cx) {
+        self.end(m, cx);
+    }
+    fn tick(&mut self, m: &mut Mob, cx: &mut Cx) {
+        if self.mid_jump {
+            return;
+        }
+        let Some(jump) = self.chosen else {
+            self.tries -= 1;
+            self.pick(m, cx.w, cx.lr);
+            return;
+        };
+        m.look_at(self.look);
+        self.prepare += 1;
+        if self.prepare < PREPARE_JUMP_DURATION {
+            return;
+        }
+        // The leap: the body's facing, no friction, the arc's velocity
+        // lengthened by jump boost.
+        m.yaw = m.body_yaw;
+        m.extra.frog.discard_friction = true;
+        let len = jump.length();
+        let boost = m
+            .extra
+            .effects
+            .iter()
+            .find(|e| e.0 == "minecraft:jump_boost")
+            .map_or(0.0, |e| f64::from(0.1_f32 * (e.2 + 1) as f32));
+        m.velocity = jump.scale((len + boost) / len);
+        self.mid_jump = true;
+        let at = [m.position.x, m.position.y, m.position.z];
+        cx.events
+            .push(MobEvent::Sound("entity.frog.long_jump", at, 1.0, 1.0));
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use horizon_core::random::LegacyRandom;
+
+    fn frog() -> Mob {
+        let mut kind = crate::mobs::sensor_scan_tests::kind();
+        let k = std::sync::Arc::make_mut(&mut kind);
+        k.id = "minecraft:frog".into();
+        k.species = Species::Frog;
+        Mob::new(1, kind, Vec3::new(0.5, 0.0, 0.5), 0.0)
+    }
+
+    /// `LongJumpToRandomPos.start`: the 9 x 5 x 9 box without the frog's own
+    /// block, x fastest, then y, then z, each weighted by its squared distance.
+    #[test]
+    fn the_candidates_cover_the_jump_box_in_vanilla_order() {
+        let c = candidates([10, 64, -3]);
+        assert_eq!(c.len(), 9 * 5 * 9 - 1);
+        assert_eq!(c[0], ([6, 62, -7], 16 + 4 + 16));
+        assert_eq!(c[1], ([7, 62, -7], 9 + 4 + 16));
+        assert_eq!(c[9], ([6, 63, -7], 16 + 1 + 16));
+        assert_eq!(c[45], ([6, 62, -6], 16 + 4 + 9));
+        assert!(!c.iter().any(|(p, _)| *p == [10, 64, -3]));
+        assert_eq!(c.last().unwrap().0, [14, 66, 1]);
+    }
+
+    /// `WeightedRandom.getRandomItem`: `nextInt(total)` walked down the
+    /// list, and the drawn candidate is removed.
+    #[test]
+    fn a_draw_takes_the_weighted_candidate_out() {
+        let mut j = LongJump {
+            candidates: vec![([0, 0, 0], 1), ([1, 0, 0], 4), ([2, 0, 0], 9)],
+            ..LongJump::default()
+        };
+        let mut r = LegacyRandom::new(7);
+        let mut lr = r.clone();
+        let pick = r.next_int_bound(14).unwrap();
+        let want = if pick < 1 {
+            0
+        } else if pick < 5 {
+            1
+        } else {
+            2
+        };
+        assert_eq!(j.draw(&mut lr).unwrap().0, [want, 0, 0]);
+        assert_eq!(j.candidates.len(), 2);
+        assert!(!j.candidates.iter().any(|c| c.0 == [want, 0, 0]));
+    }
+
+    /// `CountDownCooldownTicks`: the memory falls by one a tick and is gone
+    /// the tick after it reached 0; the sample is 100..=140, halved after a
+    /// failed search, drawn from the level's random and not the frog's.
+    #[test]
+    fn the_long_jump_cooldown_counts_down_and_is_erased() {
+        let mut m = frog();
+        let own = m.random.state();
+        sample_cooldown(&mut m, &mut LegacyRandom::new(3), 2);
+        let t = jump_cooldown(&m).unwrap();
+        assert!((50..=70).contains(&t));
+        assert_eq!(m.random.state(), own);
+        set_jump_cooldown(&mut m, Some(1));
+        set_jump_cooldown(&mut m, Some(0));
+        assert_eq!(jump_cooldown(&m), Some(0));
+        set_jump_cooldown(&mut m, None);
+        assert_eq!(jump_cooldown(&m), None);
+        assert!(!m.extra.memories.iter().any(|x| x.0 == LONG_JUMP_COOLDOWN));
+    }
+}

crates/horizon-client/src/mobs/goals.rs

@@ -4,7 +4,7 @@ use super::{Mob, MobEvent, MobWorld, Seen, Species, Who, world::TargetInfo};
 use horizon_core::{
     geometry::{Aabb, Vec3},
     jmath,
-    random::RandomSource,
+    random::{LegacyRandom, RandomSource},
 };
 use std::sync::Arc;
 
@@ -16,6 +16,9 @@ pub const TARGET: u8 = 8;
 /// What goals may read and emit during a tick.
 pub struct Cx<'a, 'w> {
     pub w: &'a MobWorld<'w>,
+    /// The level's random (`level.getRandom()`), for the draws vanilla's
+    /// behaviours make from it rather than from the mob's own.
+    pub lr: &'a mut LegacyRandom,
     pub events: &'a mut Vec<MobEvent>,
 }
 pub trait Goal: std::fmt::Debug {

crates/horizon-client/src/mobs/living.rs

@@ -1045,8 +1045,8 @@ impl Mob {
         } else {
             y -= self.gravity();
         }
-        // LivingEntity.shouldDiscardFriction (a breeze's long jump).
-        if super::breeze::discards_friction(self) {
+        // LivingEntity.shouldDiscardFriction (a breeze's or a frog's long jump).
+        if super::breeze::discards_friction(self) || self.extra.frog.discard_friction {
             self.velocity = Vec3::new(movement.x, y, movement.z);
             return;
         }

crates/horizon-client/src/mobs/monster_brain.rs

@@ -783,6 +783,7 @@ impl B {
                 m.swing();
                 let mut gcx = Cx {
                     w,
+                    lr: cx.lr,
                     events: cx.events,
                 };
                 super::ai::do_hurt_target(m, target, &mut gcx);

crates/horizon-client/src/mobs/nav.rs

@@ -232,7 +232,7 @@ impl Mob {
         }
         q
     }
-    fn create_path_raw(
+    pub(super) fn create_path_raw(
         &mut self,
         w: &MobWorld,
         targets: &[[i32; 3]],

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

@@ -1061,8 +1061,14 @@ fn red_overlay(m: &Mob) -> bool {
 }
 fn species_scale(m: &Mob, alpha: f32) -> glam::Mat4 {
     if avatar(m) {
-        // AvatarRenderer.scale, shared by the inventory and world renderer.
-        return glam::Mat4::from_scale(glam::Vec3::splat(0.9375));
+        // AvatarRenderer.scale, shared by the inventory and world renderer, on
+        // top of the entity's own `scale` (`LivingEntityRenderer.submit`).
+        let own = if m.extra.model_scale > 0.0 {
+            m.extra.model_scale
+        } else {
+            1.0
+        };
+        return glam::Mat4::from_scale(glam::Vec3::splat(0.9375 * own));
     }
     match m.species() {
         Species::Wither => {
@@ -1227,7 +1233,7 @@ pub fn render_with(
                 let shifted =
                     camera - glam::DVec3::new(off[0] + w[0], off[1] + w[1], off[2] + w[2]);
                 let base = base_transform(m, alpha, shifted);
-                render_visible(m, alpha, base, atlas, light, data, extra, out);
+                render_visible(m, alpha, base, atlas, light, data, extra, true, out);
             }
         }
         return;
@@ -1240,6 +1246,7 @@ pub fn render_with(
         light,
         data,
         extra,
+        true,
         out,
     );
 }
@@ -1285,6 +1292,24 @@ pub fn cape(
     // RenderTypes.entitySolid with OverlayTexture.NO_OVERLAY.
     draw(model, base, &poses, uv, 0xFFFF_FFFF, light, 0, out);
 }
+/// `render_with` without the body, for an avatar the viewer can't see:
+/// `LivingEntityRenderer.submit` gets no render type for an invisible body
+/// (`isBodyVisible`, `isInvisibleTo`), but its layers still draw
+/// (`HumanoidArmorLayer`: the armour in `extra`).
+#[allow(clippy::too_many_arguments)]
+pub fn render_layers(
+    m: &Mob,
+    alpha: f32,
+    camera: glam::DVec3,
+    atlas: Atlas,
+    light: u32,
+    data: &MobData,
+    extra: &[(&Part, [f32; 4], u32)],
+    out: &mut Vec<Vertex>,
+) {
+    let base = base_transform(m, alpha, camera);
+    render_visible(m, alpha, base, atlas, light, data, extra, false, out);
+}
 /// A mob drawn under `origin` instead of at its position (the spinning mob
 /// of `SpawnerRenderer.submitEntityInSpawner`).
 pub fn render_posed(
@@ -1297,7 +1322,7 @@ pub fn render_posed(
     out: &mut Vec<Vertex>,
 ) {
     let base = base_transform_at(m, alpha, origin);
-    render_visible(m, alpha, base, atlas, light, data, &[], out);
+    render_visible(m, alpha, base, atlas, light, data, &[], true, out);
 }
 #[allow(clippy::too_many_arguments)]
 fn render_visible(
@@ -1308,6 +1333,7 @@ fn render_visible(
     light: u32,
     data: &MobData,
     extra: &[(&Part, [f32; 4], u32)],
+    body_visible: bool,
     out: &mut Vec<Vertex>,
 ) {
     let overlay = u32::from(red_overlay(m));
@@ -1321,7 +1347,7 @@ fn render_visible(
     let mut poses = Poses::new(&model);
     anim::setup(m, &s, &mut poses, &data.animations);
     let draw_body = |out: &mut Vec<Vertex>| {
-        if let Some(uv) = atlas(&texture) {
+        if body_visible && let Some(uv) = atlas(&texture) {
             draw(
                 &model,
                 base,

crates/horizon-client/src/mobs/spawner.rs

@@ -766,4 +766,11 @@ mod tests {
         assert_eq!(light_limit(Some(&tag("[I;9,2]"))), None);
         assert_eq!(encode_range((3, 3)), Tag::Int(3));
     }
+
+    #[test]
+    fn spawner_defaults_empty() {
+        let s = Spawner::default();
+        assert_eq!(s.next_data(), None);
+        assert!(s.potentials.is_empty());
+    }
 }

crates/horizon-client/src/mobs/warden.rs

@@ -454,7 +454,13 @@ pub fn do_push(m: &mut Mob, w: &MobWorld, who: Who, events: &mut Vec<MobEvent>)
 }
 /// `Warden.doHurtTarget`: the attack keyframes (entity event 4), the impact
 /// sound, a sonic boom cooldown, then `Mob.doHurtTarget`.
-pub(super) fn do_hurt_target(m: &mut Mob, target: Who, w: &MobWorld, events: &mut Vec<MobEvent>) {
+pub(super) fn do_hurt_target(
+    m: &mut Mob,
+    target: Who,
+    w: &MobWorld,
+    lr: &mut LegacyRandom,
+    events: &mut Vec<MobEvent>,
+) {
     m.anim.states[ROAR].stop();
     m.anim.states[ATTACK].start(m.age as f32);
     events.push(MobEvent::EntityEvent {
@@ -465,7 +471,7 @@ pub(super) fn do_hurt_target(m: &mut Mob, target: Who, w: &MobWorld, events: &mu
     let pitch = voice_pitch(m);
     sound(m, "entity.warden.attack_impact", 10.0, pitch, events);
     warden_brain::mem(m).sonic_boom_cooldown.set_ttl((), 40);
-    let mut cx = warden_brain::cx(w, events);
+    let mut cx = warden_brain::cx(w, lr, events);
     super::ai::do_hurt_target(m, target, &mut cx);
 }
 

crates/horizon-client/src/mobs/warden_brain.rs

@@ -962,7 +962,7 @@ impl B {
                 }
                 mem(m).look_target.set(Tracker::Entity(target, true));
                 m.swing();
-                warden::do_hurt_target(m, target, w, cx.events);
+                warden::do_hurt_target(m, target, w, cx.lr, cx.events);
                 mem(m)
                     .attack_cooling_down
                     .set_ttl(true, MELEE_ATTACK_COOLDOWN);
@@ -1188,8 +1188,12 @@ fn swim_condition(m: &Mob) -> bool {
     m.fluids.water > m.fluid_jump_threshold() || m.fluids.in_lava
 }
 /// The `Cx` the mob library's attacks take.
-pub(super) fn cx<'a, 'w>(w: &'a MobWorld<'w>, events: &'a mut Vec<MobEvent>) -> Cx<'a, 'w> {
-    Cx { w, events }
+pub(super) fn cx<'a, 'w>(
+    w: &'a MobWorld<'w>,
+    lr: &'a mut LegacyRandom,
+    events: &'a mut Vec<MobEvent>,
+) -> Cx<'a, 'w> {
+    Cx { w, lr, events }
 }
 
 // ---- Printing ---------------------------------------------------------------

crates/horizon-client/src/mod_content.rs

@@ -19,7 +19,7 @@ use horizon_mods::content::{Block, Content, Rarity};
 use horizon_world::nbt::{self, JavaString, Limits, Tag};
 use serde::{Deserialize, Serialize, de};
 use std::{
-    collections::BTreeMap,
+    collections::{BTreeMap, BTreeSet},
     fmt, fs,
     ops::Range,
     path::{Path, PathBuf},
@@ -129,6 +129,11 @@ impl J {
             _ => None,
         }
     }
+    fn remove(&mut self, key: &str) {
+        if let J::Obj(o) = self {
+            o.retain(|(k, _)| k != key);
+        }
+    }
     fn get_mut(&mut self, key: &str) -> Option<&mut J> {
         match self {
             J::Obj(o) => o.iter_mut().find(|(k, _)| k == key).map(|(_, v)| v),
@@ -235,6 +240,7 @@ struct NewItem {
     rename: Rename,
     max_stack_size: Option<u8>,
     rarity: Option<Rarity>,
+    components: Vec<(String, J)>,
 }
 
 struct Plan<'a> {
@@ -248,6 +254,26 @@ struct Plan<'a> {
     sounds: BTreeMap<String, J>,
 }
 
+/// An item's component patch on its entry; `known` holds every type a vanilla item has, so typos fail.
+fn patch_components(
+    entry: &mut J,
+    patch: &[(String, J)],
+    known: &BTreeSet<String>,
+) -> std::result::Result<(), String> {
+    for (key, value) in patch {
+        let kind = key.strip_prefix('!').unwrap_or(key);
+        if !known.contains(kind) {
+            return Err(format!("{kind} is no component a vanilla item has"));
+        }
+        if kind == key {
+            entry.set(key, value.clone());
+        } else {
+            entry.remove(kind);
+        }
+    }
+    Ok(())
+}
+
 fn read_json(path: &Path) -> Result<J> {
     Ok(serde_json::from_slice(&fs::read(path)?).map_err(|e| format!("{}: {e}", path.display()))?)
 }
@@ -356,6 +382,7 @@ impl<'a> Plan<'a> {
                     rename: Rename::new(item, &b.decl.id),
                     max_stack_size: None,
                     rarity: None,
+                    components: Vec::new(),
                 });
             }
         }
@@ -365,9 +392,18 @@ impl<'a> Plan<'a> {
                     rename: Rename::new(&i.template, &i.id),
                     max_stack_size: i.max_stack_size,
                     rarity: i.rarity,
+                    components: i
+                        .components
+                        .iter()
+                        .map(|(k, v)| Ok((k.clone(), serde_json::from_value(v.clone())?)))
+                        .collect::<std::result::Result<_, serde_json::Error>>()
+                        .map_err(|e| format!("{}: {e}", i.id))?,
                 });
             }
         }
+        // Block items and standalone items share the same registry. Sort
+        // them together by mod ID and entry name before assigning IDs.
+        items.sort_by(|a, b| a.rename.to.cmp(&b.rename.to));
         Ok(Plan {
             blocks,
             items,
@@ -458,7 +494,18 @@ impl<'a> Plan<'a> {
 
     /// Adds each new item's copy of its template's entry to a map by name;
     /// `components` applies the overrides (items.json).
-    fn items(&self, map: &mut J, components: bool) {
+    fn items(&self, map: &mut J, components: bool) -> Result<()> {
+        let known: BTreeSet<String> = match map {
+            J::Obj(entries) if components => entries
+                .iter()
+                .filter_map(|(_, v)| match v {
+                    J::Obj(c) => Some(c.iter().map(|(k, _)| k.clone())),
+                    _ => None,
+                })
+                .flatten()
+                .collect(),
+            _ => BTreeSet::new(),
+        };
         for i in &self.items {
             let Some(v) = map.get(&i.rename.from) else {
                 continue;
@@ -478,9 +525,12 @@ impl<'a> Plan<'a> {
                     };
                     v.set("minecraft:rarity", J::Str(r.into()));
                 }
+                patch_components(&mut v, &i.components, &known)
+                    .map_err(|e| format!("{}: {e}", i.rename.to))?;
             }
             map.set(&i.rename.to, v);
         }
+        Ok(())
     }
 
     /// One JSON table, rewritten.
@@ -521,7 +571,7 @@ impl<'a> Plan<'a> {
                         blocks.push(v);
                     }
                 }
-                self.items(doc.at("items").ok_or("no items")?, false);
+                self.items(doc.at("items").ok_or("no items")?, false)?;
                 for odds in ["fire/burnOdds", "fire/igniteOdds"] {
                     if let Some(map) = doc.at(odds) {
                         self.names(map, false);
@@ -537,7 +587,7 @@ impl<'a> Plan<'a> {
                     self.names(map, false);
                 }
             }
-            "items.json" => self.items(doc, true),
+            "items.json" => self.items(doc, true)?,
             "registries.json" => {
                 // Network ids: the game and its server map items and blocks through
                 // this report, so new ones get the ids after vanilla's, in plan order.
@@ -698,6 +748,29 @@ const WORLDGEN_BUNDLES: [(&str, &str); 6] = [
     ("placed_feature", "worldgen/placed_features.json"),
 ];
 
+/// The registry of `command-registries.json` that each bundle's ids join,
+/// for the commands that suggest them (`/locate`, `/place`).
+const COMMAND_REGISTRIES: [(&str, &str); 6] = [
+    ("worldgen/structures.json", "minecraft:worldgen/structure"),
+    (
+        "worldgen/structure_sets.json",
+        "minecraft:worldgen/structure_set",
+    ),
+    (
+        "worldgen/template_pools.json",
+        "minecraft:worldgen/template_pool",
+    ),
+    (
+        "worldgen/processor_lists.json",
+        "minecraft:worldgen/processor_list",
+    ),
+    ("worldgen/features.json", "minecraft:worldgen/feature"),
+    (
+        "worldgen/placed_features.json",
+        "minecraft:worldgen/placed_feature",
+    ),
+];
+
 /// A mod file that adds to a worldgen bundle: (bundle, id).
 fn worldgen_entry(file: &str) -> Option<(&'static str, String)> {
     let (ns, rest) = file.strip_prefix("data/")?.split_once("/worldgen/")?;
@@ -838,6 +911,9 @@ impl Overlay<'_> {
         Ok(())
     }
 }
+fn out_path(overlay: &Overlay<'_>, rel: &str) -> PathBuf {
+    overlay.out.join(rel)
+}
 #[cfg(unix)]
 fn link(target: &Path, at: &Path) -> std::io::Result<()> {
     std::os::unix::fs::symlink(target, at)
@@ -1208,6 +1284,32 @@ pub fn build(base: &Path, mods: &[ContentMod], out: &Path) -> Result<Vec<String>
         }
         overlay.write(bundle, &serde_json::to_vec(&doc)?)?;
     }
+    // The commands suggest ids from `command-registries.json`: add the
+    // structures, pools, sets and features the mods bring.
+    let registries = out_path(&overlay, "command-registries.json");
+    if let Ok(mut doc) = read_json(&registries) {
+        // Registry names hold `/`, so each key is looked up by itself.
+        let mut add = |keys: &[&str], new: &[J]| {
+            let found = keys.iter().try_fold(&mut doc, |j, k| j.get_mut(k));
+            if let Some(J::Arr(ids)) = found {
+                for id in new {
+                    if !ids.contains(id) {
+                        ids.push(id.clone());
+                    }
+                }
+            }
+        };
+        for (bundle, registry) in COMMAND_REGISTRIES {
+            let new: Vec<J> = worldgen
+                .get(bundle)
+                .into_iter()
+                .flatten()
+                .map(|(id, _)| J::Str(id.clone()))
+                .collect();
+            add(&["by_registry", registry, "ids"], &new);
+        }
+        overlay.write("command-registries.json", &serde_json::to_vec(&doc)?)?;
+    }
     // A block without its own blockstate looks like its template, so every
     // state still has a model.
     for m in mods {

crates/horizon-client/src/mod_content_tests.rs

@@ -33,6 +33,40 @@ fn json_keeps_key_order_and_numbers() {
     assert_eq!(serde_json::to_string(&doc).unwrap(), text);
 }
 
+#[test]
+fn item_components_patch_the_template_entry() {
+    let mut entry: J =
+        serde_json::from_str(r#"{"minecraft:max_damage": 250, "minecraft:repairable": {}}"#)
+            .unwrap();
+    let known: BTreeSet<String> = [
+        "minecraft:max_damage",
+        "minecraft:repairable",
+        "minecraft:food",
+    ]
+    .map(str::to_owned)
+    .into();
+    let patch = |text: &str| -> Vec<(String, J)> {
+        let J::Obj(o) = serde_json::from_str(text).unwrap() else {
+            unreachable!()
+        };
+        o
+    };
+    patch_components(
+        &mut entry,
+        &patch(r#"{"minecraft:max_damage": 900, "!minecraft:repairable": {}, "minecraft:food": {"nutrition": 4}}"#),
+        &known,
+    )
+    .unwrap();
+    assert_eq!(
+        serde_json::to_string(&entry).unwrap(),
+        r#"{"minecraft:max_damage":900,"minecraft:food":{"nutrition":4}}"#
+    );
+    for typo in [r#"{"minecraft:fod": {}}"#, r#"{"!minecraft:fod": {}}"#] {
+        let e = patch_components(&mut entry, &patch(typo), &known).unwrap_err();
+        assert_eq!(e, "minecraft:fod is no component a vanilla item has");
+    }
+}
+
 #[test]
 fn tags_merge_without_repeats() {
     let vanilla = r#"{"values": ["minecraft:stone"]}"#;
@@ -48,6 +82,139 @@ fn tags_merge_without_repeats() {
     );
 }
 
+/// Registry IDs and state IDs must not depend on package discovery order.
+#[test]
+fn allocated_ids_follow_mod_and_entry_order_after_vanilla() {
+    let scratch = std::env::temp_dir().join(format!("horizon-mod-order-{}", std::process::id()));
+    let _ = fs::remove_dir_all(&scratch);
+    let base = scratch.join("base");
+    fs::create_dir_all(&base).unwrap();
+    fs::write(
+        base.join("facts.json"),
+        r#"{"states": [["minecraft:iron_block"], ["minecraft:iron_block"], ["minecraft:stone"]],
+            "defaults": {"minecraft:iron_block": 0, "minecraft:stone": 2}}"#,
+    )
+    .unwrap();
+    fs::write(
+        base.join("gameplay-facts.json"),
+        r#"{"states": [{"item":"minecraft:iron_block"}, {"item":"minecraft:iron_block"},
+            {"item":"minecraft:stone"}]}"#,
+    )
+    .unwrap();
+    fs::write(
+        base.join("items.json"),
+        r#"{"minecraft:stone": {}, "minecraft:iron_block": {}}"#,
+    )
+    .unwrap();
+    fs::write(
+        base.join("registries.json"),
+        r#"{"minecraft:item":{"entries":{"minecraft:stone":{"protocol_id":4},
+            "minecraft:iron_block":{"protocol_id":9}}},
+            "minecraft:block":{"entries":{"minecraft:stone":{"protocol_id":7},
+            "minecraft:iron_block":{"protocol_id":11}}}}"#,
+    )
+    .unwrap();
+    fs::create_dir_all(base.join("assets/minecraft/blockstates")).unwrap();
+    fs::write(
+        base.join("assets/minecraft/blockstates/iron_block.json"),
+        "{}",
+    )
+    .unwrap();
+    fs::write(base.join("assets/minecraft/blockstates/stone.json"), "{}").unwrap();
+    let ruby = folder_mod(
+        &scratch.join("ruby"),
+        &[
+            ("horizon-mod.toml", &manifest("ruby", "")),
+            (
+                "data/ruby/horizon/block/zblock.json",
+                r#"{"template":"minecraft:stone"}"#,
+            ),
+            (
+                "data/ruby/horizon/item/aitem.json",
+                r#"{"template":"minecraft:stone"}"#,
+            ),
+        ],
+    );
+    let alpha = folder_mod(
+        &scratch.join("alpha"),
+        &[
+            ("horizon-mod.toml", &manifest("alpha", "")),
+            (
+                "data/alpha/horizon/block/zblock.json",
+                r#"{"template":"minecraft:iron_block"}"#,
+            ),
+            (
+                "data/alpha/horizon/item/aitem.json",
+                r#"{"template":"minecraft:stone"}"#,
+            ),
+        ],
+    );
+    let mut mods = vec![ruby, alpha];
+    for index in 0..2 {
+        let plan = Plan::new(&base, &mods).unwrap();
+        let blocks: Vec<_> = plan
+            .blocks
+            .iter()
+            .map(|block| {
+                (
+                    block.decl.id.as_str(),
+                    block.rename.first,
+                    block.rename.states.len(),
+                )
+            })
+            .collect();
+        assert_eq!(blocks, [("alpha:zblock", 3, 2), ("ruby:zblock", 5, 1)]);
+        let items: Vec<_> = plan
+            .items
+            .iter()
+            .map(|item| item.rename.to.as_str())
+            .collect();
+        assert_eq!(
+            items,
+            ["alpha:aitem", "alpha:zblock", "ruby:aitem", "ruby:zblock"]
+        );
+
+        // Exercise the same registry rewrite the game and server read.
+        let mut registry: J = serde_json::from_str(
+            r#"{"minecraft:item":{"entries":{"minecraft:stone":{"protocol_id":4},
+                "minecraft:iron_block":{"protocol_id":9}}},
+                "minecraft:block":{"entries":{"minecraft:stone":{"protocol_id":7},
+                "minecraft:iron_block":{"protocol_id":11}}}}"#,
+        )
+        .unwrap();
+        plan.json("registries.json", &mut registry).unwrap();
+        let registry: serde_json::Value =
+            serde_json::from_str(&serde_json::to_string(&registry).unwrap()).unwrap();
+        let id = |kind: &str, name: &str| {
+            registry[kind]["entries"][name]["protocol_id"]
+                .as_u64()
+                .unwrap()
+        };
+        assert_eq!(id("minecraft:item", "minecraft:stone"), 4);
+        assert_eq!(id("minecraft:item", "minecraft:iron_block"), 9);
+        assert_eq!(id("minecraft:item", "alpha:aitem"), 10);
+        assert_eq!(id("minecraft:item", "alpha:zblock"), 11);
+        assert_eq!(id("minecraft:item", "ruby:aitem"), 12);
+        assert_eq!(id("minecraft:item", "ruby:zblock"), 13);
+        assert_eq!(id("minecraft:block", "minecraft:stone"), 7);
+        assert_eq!(id("minecraft:block", "minecraft:iron_block"), 11);
+        assert_eq!(id("minecraft:block", "alpha:zblock"), 12);
+        assert_eq!(id("minecraft:block", "ruby:zblock"), 13);
+        drop(plan);
+
+        let output = scratch.join(format!("output-{index}"));
+        build(&base, &mods, &output).unwrap();
+        let built: serde_json::Value =
+            serde_json::from_slice(&fs::read(output.join("registries.json")).unwrap()).unwrap();
+        assert_eq!(
+            built, registry,
+            "the built root must use the tested allocation"
+        );
+        mods.reverse();
+    }
+    fs::remove_dir_all(scratch).unwrap();
+}
+
 fn prepared() -> Option<PathBuf> {
     let manifest = Path::new(env!("CARGO_MANIFEST_DIR"));
     [
@@ -61,7 +228,7 @@ fn prepared() -> Option<PathBuf> {
 /// A content mod folder: a full block, a door and an item-less glass from
 /// templates, an item, a vanilla tag addition and a language file.
 fn ruby_mod(dir: &Path) -> ContentMod {
-    let files: [(&str, &str); 8] = [
+    let files: [(&str, &str); 9] = [
         (
             "horizon-mod.toml",
             "id = \"ruby\"\nname = \"Ruby\"\nversion = \"0.1.0\"\napi = \"0.2\"\nside = \"both\"\ncapabilities = [\"registries\"]\n",
@@ -83,6 +250,14 @@ fn ruby_mod(dir: &Path) -> ContentMod {
             "data/ruby/horizon/item/ruby.json",
             r#"{"template": "minecraft:diamond", "max_stack_size": 16, "rarity": "rare"}"#,
         ),
+        (
+            "data/ruby/horizon/item/ruby_sword.json",
+            r#"{"template": "minecraft:iron_sword", "components": {"minecraft:max_damage": 900,
+                "minecraft:attribute_modifiers": [{"type": "minecraft:attack_damage",
+                    "id": "minecraft:base_attack_damage", "amount": 7.0,
+                    "operation": "add_value", "slot": "mainhand"}],
+                "!minecraft:repairable": {}}}"#,
+        ),
         // Carried-over tags name blocks left out and other mods' ids too.
         (
             "data/minecraft/tags/block/mineable/pickaxe.json",
@@ -252,6 +427,12 @@ fn content_root_loads_with_every_table() {
     assert_eq!(ruby_block.block, Some(ruby));
     let gem = &items.items["ruby:ruby"];
     assert_eq!(gem.max_stack, 16);
+    let sword = &items.items["ruby:ruby_sword"];
+    let iron_sword = &items.items["minecraft:iron_sword"];
+    assert_eq!((sword.max_damage, iron_sword.max_damage), (900, 250));
+    assert_eq!(sword.modifiers.len(), 1);
+    assert_eq!(sword.modifiers[0].2, 7.0);
+    assert_eq!(sword.tool.len(), iron_sword.tool.len());
     assert!(!items.items.contains_key("ruby:ruby_glass"));
     let pickaxe = &items.block_tags["minecraft:mineable/pickaxe"];
     assert!(pickaxe.contains("ruby:ruby_block"));
@@ -679,6 +860,24 @@ fn content_root_carries_a_structure_mod() {
         assert!(!ours.contains_key("othermod:houses"));
     }
 
+    // The commands suggest the mod's structure, set and pool.
+    let registries: serde_json::Value =
+        serde_json::from_slice(&fs::read(root.join("command-registries.json")).unwrap()).unwrap();
+    for (registry, id) in [
+        ("minecraft:worldgen/structure", "huts:hut"),
+        ("minecraft:worldgen/structure_set", "huts:huts"),
+        ("minecraft:worldgen/template_pool", "huts:hut/start"),
+    ] {
+        let ids = registries["by_registry"][registry]["ids"]
+            .as_array()
+            .unwrap();
+        assert!(ids.iter().any(|v| v == id), "{registry} lacks {id}");
+        assert!(
+            ids.iter()
+                .any(|v| v.as_str().unwrap().starts_with("minecraft:"))
+        );
+    }
+
     let assets = Assets::load(&root).unwrap();
     let biomes = crate::biome::Biomes::load(&root).unwrap();
     let terrain = crate::vanillagen::VanillaTerrain::new(