Merge pull request #15570 from ilguerro/fix/parity-manual-proof-scripts

Leave the six hand-run proof scripts out of parity runs

AGENTS.md

@@ -214,7 +214,7 @@ state stays separate from the library tests. This compiles gameplay twice for ex
 | Resource packs | L: `packs.rs` + `packs/`, `pack_screen.rs`, `atlas_sources.rs`, `sprites.rs`, `mipmap.rs`, `model_library.rs`, `font.rs`, `mobs/cem.rs` + `mobs/cem_anim.rs` (OptiFine/EMF entity models and their animations); `horizon-client-core/src/lang.rs`; crates `horizon-assets`, `horizon-optifine`; G: `packs.rs` |
 | Agent control | L: `control.rs` (socket), `bin/horizon-ctl/`; G: `control.rs`, `agent.rs`, `events.rs`, `ui_control.rs` ([docs/agent-control.md](docs/agent-control.md)) |
 | Mods | crate `horizon-mods`; G: `mods.rs`; L: `mod_content.rs`, `mod_list.rs` |
-| Horizon extras, settings | L: `extras.rs`, `graphics.rs`, `settings.rs`, `minimap.rs`; G: `extras.rs`, `tweaks.rs`, `options.rs` |
+| Horizon extras, settings | L: `extras.rs`, `graphics.rs`, `settings.rs`, `minimap.rs`; G: `extras.rs` + `extras/` (each extra's glue: `mouse_tweaks.rs`, `sorting.rs`, `pvp.rs`, `reconnect.rs`), `options.rs` |
 
 ## How `Game` is organised
 

THIRD_PARTY_NOTICES.md

@@ -62,6 +62,8 @@ The GLSL frontend also resets the common type for each comma-separated declarato
 variable's array specifier does not change later variables.
 It also reads a struct member outside a constant expression through a pointer to the member,
 not out of a loaded copy of the whole struct, so a member an atomic function uses can be read.
+The shared interpolation defaults also compile with `glsl-in` alone, without needing the
+SPIR-V or WGSL frontend to enable them.
 
 ## DirectX Shader Compiler
 

crates/horizon-anticheat/src/lib.rs

@@ -206,7 +206,7 @@ impl Config {
         Ok(file.anticheat)
     }
 
-    /// Thresholds can't be negative.
+    /// Thresholds can't be negative, and neither can the timer's milliseconds.
     pub fn check(&self) -> Result<(), String> {
         for &c in Check::ALL {
             let a = self.actions(c);
@@ -220,6 +220,18 @@ impl Config {
                 ));
             }
         }
+        // A negative tolerance flags a client on time every tick, and so does a cap below minus the
+        // tolerance (the balance rests at the cap); NaN never flags, or never caps the balance. No
+        // negative number of milliseconds means anything, so all are refused.
+        if [self.timer.tolerance_ms, self.timer.max_lag_ms]
+            .iter()
+            .any(|v| !v.is_finite() || *v < 0.0)
+        {
+            return Err(
+                "anticheat.timer: tolerance_ms and max_lag_ms are numbers of milliseconds from 0 up"
+                    .into(),
+            );
+        }
         let tolerance = self.prediction.tolerance;
         if !tolerance.is_finite() || tolerance <= 0.0 {
             return Err("anticheat.prediction: tolerance is a number of blocks above 0".into());
@@ -361,6 +373,26 @@ mod tests {
         assert!(Config::from_server_toml("[anticheat.timer]\nkick = -1\n").is_err());
     }
 
+    /// A negative `tolerance_ms` flags a client on time every tick, and so does a `max_lag_ms` below
+    /// `-tolerance_ms` (the balance rests at the cap); a NaN turns the check (or its cap) off without a
+    /// word. Every negative or non-finite value is refused, as a negative threshold is.
+    #[test]
+    fn refuses_timer_settings_that_are_not_milliseconds_from_0_up() {
+        for bad in [
+            "tolerance_ms = -1",
+            "tolerance_ms = nan",
+            "tolerance_ms = inf",
+            "max_lag_ms = -1",
+            "max_lag_ms = nan",
+        ] {
+            let text = format!("[anticheat.timer]\n{bad}\n");
+            let e = Config::from_server_toml(&text).expect_err(bad);
+            assert!(e.starts_with("anticheat.timer:"), "{bad}: {e}");
+        }
+        let edge = "[anticheat.timer]\ntolerance_ms = 0\nmax_lag_ms = 0\n";
+        assert!(Config::from_server_toml(edge).is_ok());
+    }
+
     #[test]
     fn levels_rise_decay_and_act_in_order() {
         let mut c = on();

crates/horizon-anticheat/src/timer.rs

@@ -45,6 +45,11 @@ mod tests {
 
     /// `seconds` of server ticks of `server_ms` each, with `per_tick` client ticks handled in each.
     fn run(b: &mut Balance, server_ms: f64, per_tick: f64, seconds: f64) -> usize {
+        run_at(b, 20.0, server_ms, per_tick, seconds)
+    }
+
+    /// [`run`] at the tick rate `rate` (`/tick rate`), which the client's ticks follow.
+    fn run_at(b: &mut Balance, rate: f32, server_ms: f64, per_tick: f64, seconds: f64) -> usize {
         let c = TimerConfig::default();
         let mut owed = 0.0;
         let mut flags = 0;
@@ -53,12 +58,31 @@ mod tests {
             owed += per_tick;
             while owed >= 1.0 {
                 owed -= 1.0;
-                flags += usize::from(b.tick_end(20.0, &c).is_some());
+                flags += usize::from(b.tick_end(rate, &c).is_some());
             }
         }
         flags
     }
 
+    /// At another tick rate a vanilla client ticks at the rate the server sent it, and each of its
+    /// ticks is worth `1000 / rate` ms: never flagged on time, flagged again and again 1.5 times as fast.
+    #[test]
+    fn the_balance_follows_the_tick_rate() {
+        for rate in [10.0_f32, 60.0] {
+            let tick_ms = 1000.0 / f64::from(rate);
+            assert_eq!(
+                run_at(&mut Balance::default(), rate, tick_ms, 1.0, 600.0),
+                0,
+                "on time at {rate}"
+            );
+            // Half a tick ahead every server tick: 75 flags in a minute at 10 a second, 94 at 60.
+            let flags = run_at(&mut Balance::default(), rate, tick_ms, 1.5, 60.0);
+            assert!(flags >= 50, "1.5 times as fast at {rate}: {flags} flags");
+        }
+        // The rate counts: at 10 a second, a client sending 20 ticks a second is twice as fast.
+        assert!(run_at(&mut Balance::default(), 10.0, 100.0, 2.0, 60.0) >= 50);
+    }
+
     #[test]
     fn a_vanilla_client_is_never_flagged() {
         let mut b = Balance::default();

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

@@ -1442,6 +1442,8 @@ impl Audio {
         } else {
             Err("no output on a dedicated server".into())
         };
+        // Without `audio` a stream can't exist (`Infallible`), so the `Ok` arm never runs.
+        #[cfg_attr(not(feature = "audio"), allow(unreachable_code))]
         let (stream, live) = match opened {
             Ok(v) => (Some(v), true),
             Err(e) => {

crates/horizon-client-render/src/chunk/block_entity.rs

@@ -465,6 +465,9 @@ pub struct Jukebox {
     /// reference exists. Keep this separate from legacy playback adoption.
     pub song_clock_present: bool,
     pub playing: bool,
+    /// A clock a save brought back, not playing yet: `setSongWithoutPlaying`
+    /// keeps the song and its clock without the sound's level event 1010.
+    pub loaded_clock: bool,
 }
 impl Jukebox {
     /// `JukeboxBlockEntity.getTheItem`: the disc it holds.

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

@@ -210,6 +210,7 @@ mod hdr_icc;
 mod hdr_start;
 mod hdr_stats;
 pub(crate) mod hud_coverage;
+mod in_flight;
 pub use hdr::{Calibration as HdrCalibration, Output as HdrOutput};
 mod hold;
 pub use hold::WorldHold;
@@ -12351,133 +12352,6 @@ pub(crate) fn copy_frame(
     );
     buffer
 }
-impl Renderer {
-    /// The frame's readbacks to start right after its submission (on the submit thread when
-    /// the frame goes there): occlusion culling's results (`cull`) and GPU culling's
-    /// statistics. GPU frames leave occlusion culling off, so a frame has one at most.
-    fn after_submit(&mut self) -> Option<submit::AfterSubmit> {
-        let cull = self.cull.as_mut().and_then(|c| c.submitted());
-        let gpu = self.gpu_culling.as_mut().and_then(|g| g.submitted());
-        match (cull, gpu) {
-            (Some(c), Some(g)) => Some(Box::new(move || {
-                c();
-                g();
-            })),
-            (Some(c), None) => Some(Box::new(c)),
-            (None, Some(g)) => Some(Box::new(g)),
-            (None, None) => None,
-        }
-    }
-    /// Frame `frame`'s statistics shown, unless a newer frame's are: a CPU frame's as it is
-    /// drawn, a GPU frame's when its counts come back (`GpuCulling::collect`).
-    fn show_stats(&mut self, frame: u64, [sections, draws, calls]: [usize; 3]) {
-        if frame > self.stats_frame {
-            self.stats_frame = frame;
-            (
-                self.drawn_sections,
-                self.section_draws,
-                self.section_draw_calls,
-            ) = (sections, draws, calls);
-        }
-    }
-    /// Frames between the last one drawn and the one whose statistics are shown: 0 after a
-    /// CPU frame, one to three in GPU frames, while their counts are on their way back.
-    pub fn stats_lag(&self) -> u64 {
-        self.frame_serial - self.stats_frame
-    }
-    /// Take in the frame the submit thread submitted: start its readbacks and, offscreen,
-    /// keep at most two frames ahead of the GPU, as a frame submitted in place does.
-    fn land_frame(&mut self) {
-        let Some(offscreen) = self.deferred.take() else {
-            return;
-        };
-        let submission = self.queue.landed();
-        if let Some(timer) = &mut self.gpu_timer {
-            timer.submitted(&self.queue);
-            timer.collect(&self.device, &mut self.gpu_times);
-        }
-        if let Some(Some(timer)) = Self::pass_timer(&mut self.pack_post, &mut self.native) {
-            timer.submitted(&self.queue);
-        }
-        if let Some(timer) = &mut self.own_timing {
-            timer.submitted(&self.queue);
-        }
-        if offscreen && let Some(submission) = submission {
-            self.in_flight.push_back(submission);
-            if !self.paced_elsewhere {
-                self.wait_frames();
-            }
-        }
-    }
-    /// No swapchain paces offscreen frames: keep two on the GPU at most.
-    pub fn wait_in_flight(&mut self) {
-        self.land_frame();
-        self.wait_frames();
-    }
-    /// The frame on the submit thread submitted: a surface reconfigure waits for the
-    /// device and breaks if a frame is submitted while it waits, and the compositor
-    /// copies views after them. (The end of a frame already lands the frames of the
-    /// turn before; this is the turn's own.)
-    pub fn wait_submissions(&mut self) {
-        self.queue.wait();
-    }
-    fn wait_frames(&mut self) {
-        while self.in_flight.len() > 2 {
-            let index = self.in_flight.pop_front();
-            let _ = self.device.poll(wgpu::PollType::Wait {
-                submission_index: index,
-                timeout: Some(std::time::Duration::from_secs(5)),
-            });
-        }
-    }
-    /// 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,
-    ) -> 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];
-            let format = self.config.format.remove_srgb_suffix();
-            // The layered float frame maps the world to SDR, then adds the HUD as drawn.
-            // Other 16-bit frames keep their clipped 8-bit copy.
-            let copy = self
-                .hdr
-                .as_mut()
-                .and_then(|hdr| {
-                    hdr.sdr_screenshot(&self.device, encoder, format, request.size.is_some())
-                })
-                .or_else(|| {
-                    (texture.format() != format && texture.format() == self.output.frame.format)
-                        .then(|| {
-                            self.readback
-                                .unorm_copy(&self.device, encoder, texture, format)
-                        })
-                });
-            let texture = copy.as_ref().unwrap_or(texture);
-            Some((request, copy_frame(&self.device, encoder, texture, size)))
-        } else {
-            let error = format!(
-                "screenshots need a 32-bit surface format, not {:?}",
-                self.config.format
-            );
-            if request.background {
-                self.saved_screenshots.push(screenshot_save::Saved {
-                    path: request.path,
-                    result: Err(error),
-                    hdr: None,
-                });
-            } else {
-                self.screenshot_result = Some(Err(error));
-            }
-            None
-        }
-    }
-}
 /// `screenshots/2026-10-28_12.00.00.png` -> `screenshots/2026-10-28_12.00.00-hdr.png`.
 fn hdr_screenshot_path(path: &std::path::Path) -> PathBuf {
     let stem = path.file_stem().unwrap_or_default().to_string_lossy();
@@ -12583,56 +12457,8 @@ fn block_entities_within_reach<'a>(
         })
         .flatten()
 }
-/// Camera-relative clip planes (`Frustum`).
-#[derive(Clone, Copy, Debug)]
-pub struct Frustum {
-    planes: [Vec4; 6],
-}
-impl Frustum {
-    /// Whether the camera-relative box `min..max` is at least partly inside.
-    pub fn intersects(&self, min: Vec3, max: Vec3) -> bool {
-        !self.planes.iter().any(|p| {
-            let sign = p.truncate().cmpge(Vec3::ZERO);
-            let v = Vec3::select(sign, max, min);
-            p.truncate().dot(v) + p.w < 0.0
-        })
-    }
-    /// Whether a camera-relative sphere is at least partly inside. Frustum
-    /// planes are normalized, so each test needs only one dot product and a
-    /// radius comparison.
-    pub fn intersects_sphere(&self, center: Vec3, radius: f32) -> bool {
-        if !center.is_finite() || !radius.is_finite() || radius < 0.0 {
-            return true;
-        }
-        !self
-            .planes
-            .iter()
-            .any(|plane| plane.truncate().dot(center) + plane.w < -radius)
-    }
-    /// Depth clip planes alone: X/Y projection jitter cannot change this test.
-    /// Retaining side-of-screen geometry makes this safe before TAA selects a phase.
-    pub fn intersects_depth(&self, min: Vec3, max: Vec3) -> bool {
-        if !min.is_finite() || !max.is_finite() || !min.cmple(max).all() {
-            return true;
-        }
-        !self.planes[4..].iter().any(|p| {
-            let sign = p.truncate().cmpge(Vec3::ZERO);
-            let v = Vec3::select(sign, max, min);
-            p.truncate().dot(v) + p.w < 0.0
-        })
-    }
-    /// Whether the camera-relative box `min..max` is entirely inside. Then
-    /// `intersects` accepts every box within it: each plane's distance only
-    /// grows from this box's nearest corner to the inner box's farthest, and
-    /// rounding keeps that order.
-    pub fn contains(&self, min: Vec3, max: Vec3) -> bool {
-        self.planes.iter().all(|p| {
-            let sign = p.truncate().cmpge(Vec3::ZERO);
-            let v = Vec3::select(sign, min, max);
-            p.truncate().dot(v) + p.w >= 0.0
-        })
-    }
-}
+mod view_frustum;
+pub use view_frustum::Frustum;
 /// Vanilla's `Projection`: reversed depth (near maps to 1, far to 0, tests
 /// are GREATER_THAN_OR_EQUAL), which keeps far faces a hair apart, like
 /// fire_side's 0.01 pixel in front of its block, from z-fighting.

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

@@ -0,0 +1,132 @@
+//! Frames in flight: the readbacks a submission starts, landing frames the submit thread
+//! submitted, keeping offscreen frames at most two ahead of the GPU, and a screenshot's copy.
+
+use super::{Renderer, ScreenshotRequest, copy_frame, screenshot_save, submit};
+
+impl Renderer {
+    /// The frame's readbacks to start right after its submission (on the submit thread when
+    /// the frame goes there): occlusion culling's results (`cull`) and GPU culling's
+    /// statistics. GPU frames leave occlusion culling off, so a frame has one at most.
+    pub(super) fn after_submit(&mut self) -> Option<submit::AfterSubmit> {
+        let cull = self.cull.as_mut().and_then(|c| c.submitted());
+        let gpu = self.gpu_culling.as_mut().and_then(|g| g.submitted());
+        match (cull, gpu) {
+            (Some(c), Some(g)) => Some(Box::new(move || {
+                c();
+                g();
+            })),
+            (Some(c), None) => Some(Box::new(c)),
+            (None, Some(g)) => Some(Box::new(g)),
+            (None, None) => None,
+        }
+    }
+    /// Frame `frame`'s statistics shown, unless a newer frame's are: a CPU frame's as it is
+    /// drawn, a GPU frame's when its counts come back (`GpuCulling::collect`).
+    pub(super) fn show_stats(&mut self, frame: u64, [sections, draws, calls]: [usize; 3]) {
+        if frame > self.stats_frame {
+            self.stats_frame = frame;
+            (
+                self.drawn_sections,
+                self.section_draws,
+                self.section_draw_calls,
+            ) = (sections, draws, calls);
+        }
+    }
+    /// Frames between the last one drawn and the one whose statistics are shown: 0 after a
+    /// CPU frame, one to three in GPU frames, while their counts are on their way back.
+    pub fn stats_lag(&self) -> u64 {
+        self.frame_serial - self.stats_frame
+    }
+    /// Take in the frame the submit thread submitted: start its readbacks and, offscreen,
+    /// keep at most two frames ahead of the GPU, as a frame submitted in place does.
+    pub(super) fn land_frame(&mut self) {
+        let Some(offscreen) = self.deferred.take() else {
+            return;
+        };
+        let submission = self.queue.landed();
+        if let Some(timer) = &mut self.gpu_timer {
+            timer.submitted(&self.queue);
+            timer.collect(&self.device, &mut self.gpu_times);
+        }
+        if let Some(Some(timer)) = Self::pass_timer(&mut self.pack_post, &mut self.native) {
+            timer.submitted(&self.queue);
+        }
+        if let Some(timer) = &mut self.own_timing {
+            timer.submitted(&self.queue);
+        }
+        if offscreen && let Some(submission) = submission {
+            self.in_flight.push_back(submission);
+            if !self.paced_elsewhere {
+                self.wait_frames();
+            }
+        }
+    }
+    /// No swapchain paces offscreen frames: keep two on the GPU at most.
+    pub fn wait_in_flight(&mut self) {
+        self.land_frame();
+        self.wait_frames();
+    }
+    /// The frame on the submit thread submitted: a surface reconfigure waits for the
+    /// device and breaks if a frame is submitted while it waits, and the compositor
+    /// copies views after them. (The end of a frame already lands the frames of the
+    /// turn before; this is the turn's own.)
+    pub fn wait_submissions(&mut self) {
+        self.queue.wait();
+    }
+    pub(super) fn wait_frames(&mut self) {
+        while self.in_flight.len() > 2 {
+            let index = self.in_flight.pop_front();
+            let _ = self.device.poll(wgpu::PollType::Wait {
+                submission_index: index,
+                timeout: Some(std::time::Duration::from_secs(5)),
+            });
+        }
+    }
+    /// Take a screenshot request: queue the frame's copy, or report why the
+    /// frame cannot be read back.
+    pub(super) fn take_readback(
+        &mut self,
+        request: ScreenshotRequest,
+        encoder: &mut wgpu::CommandEncoder,
+        texture: &wgpu::Texture,
+    ) -> 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];
+            let format = self.config.format.remove_srgb_suffix();
+            // The layered float frame maps the world to SDR, then adds the HUD as drawn.
+            // Other 16-bit frames keep their clipped 8-bit copy.
+            let copy = self
+                .hdr
+                .as_mut()
+                .and_then(|hdr| {
+                    hdr.sdr_screenshot(&self.device, encoder, format, request.size.is_some())
+                })
+                .or_else(|| {
+                    (texture.format() != format && texture.format() == self.output.frame.format)
+                        .then(|| {
+                            self.readback
+                                .unorm_copy(&self.device, encoder, texture, format)
+                        })
+                });
+            let texture = copy.as_ref().unwrap_or(texture);
+            Some((request, copy_frame(&self.device, encoder, texture, size)))
+        } else {
+            let error = format!(
+                "screenshots need a 32-bit surface format, not {:?}",
+                self.config.format
+            );
+            if request.background {
+                self.saved_screenshots.push(screenshot_save::Saved {
+                    path: request.path,
+                    result: Err(error),
+                    hdr: None,
+                });
+            } else {
+                self.screenshot_result = Some(Err(error));
+            }
+            None
+        }
+    }
+}

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

@@ -0,0 +1,252 @@
+//! The camera's view frustum, as camera-relative clip planes.
+
+use glam::{Vec3, Vec4};
+
+/// Camera-relative clip planes (`Frustum`).
+#[derive(Clone, Copy, Debug)]
+pub struct Frustum {
+    pub(super) planes: [Vec4; 6],
+}
+impl Frustum {
+    /// Whether the camera-relative box `min..max` is at least partly inside.
+    pub fn intersects(&self, min: Vec3, max: Vec3) -> bool {
+        !self.planes.iter().any(|p| {
+            let sign = p.truncate().cmpge(Vec3::ZERO);
+            let v = Vec3::select(sign, max, min);
+            p.truncate().dot(v) + p.w < 0.0
+        })
+    }
+    /// Whether a camera-relative sphere is at least partly inside. Frustum
+    /// planes are normalized, so each test needs only one dot product and a
+    /// radius comparison.
+    pub fn intersects_sphere(&self, center: Vec3, radius: f32) -> bool {
+        if !center.is_finite() || !radius.is_finite() || radius < 0.0 {
+            return true;
+        }
+        !self
+            .planes
+            .iter()
+            .any(|plane| plane.truncate().dot(center) + plane.w < -radius)
+    }
+    /// Depth clip planes alone: X/Y projection jitter cannot change this test.
+    /// Retaining side-of-screen geometry makes this safe before TAA selects a phase.
+    pub fn intersects_depth(&self, min: Vec3, max: Vec3) -> bool {
+        if !min.is_finite() || !max.is_finite() || !min.cmple(max).all() {
+            return true;
+        }
+        !self.planes[4..].iter().any(|p| {
+            let sign = p.truncate().cmpge(Vec3::ZERO);
+            let v = Vec3::select(sign, max, min);
+            p.truncate().dot(v) + p.w < 0.0
+        })
+    }
+    /// Whether the camera-relative box `min..max` is entirely inside. Then
+    /// `intersects` accepts every box within it: each plane's distance only
+    /// grows from this box's nearest corner to the inner box's farthest, and
+    /// rounding keeps that order.
+    pub fn contains(&self, min: Vec3, max: Vec3) -> bool {
+        self.planes.iter().all(|p| {
+            let sign = p.truncate().cmpge(Vec3::ZERO);
+            let v = Vec3::select(sign, min, max);
+            p.truncate().dot(v) + p.w >= 0.0
+        })
+    }
+    /// Whether the camera-relative `point` is on or inside every plane (vanilla's
+    /// `Frustum.pointInFrustum`). A point that is not finite is kept: a test that cannot
+    /// tell must not hide the particle.
+    pub fn contains_point(&self, point: Vec3) -> bool {
+        if !point.is_finite() {
+            return true;
+        }
+        self.planes
+            .iter()
+            .all(|plane| plane.truncate().dot(point) + plane.w >= 0.0)
+    }
+    /// The same frustum seen from a camera moved `blocks` back along the view direction
+    /// (vanilla's `Frustum.offset`): the sides open up near the camera and the near plane
+    /// moves behind it, so what sits just behind or beside the camera stays inside.
+    ///
+    /// The view direction is the normal of the depth planes (the two are opposite), signed
+    /// towards where the side planes point. A frustum that has no direction to pull along
+    /// comes back unchanged: a box with no depth planes (the shadow pass's), and a box whose
+    /// sides are parallel to the view direction (an orthographic projection), where the side
+    /// normals cancel and say nothing about which way is forward.
+    pub fn pulled_back(&self, blocks: f32) -> Frustum {
+        let sides: Vec3 = self.planes[..4].iter().map(|p| p.truncate()).sum();
+        let depth = self.planes[4].truncate();
+        let along = depth.dot(sides);
+        // A perspective frustum's four side normals each lean forward, so this is well above 1.
+        if along.abs() < 1.0e-3 {
+            return *self;
+        }
+        let toward_sides = if along > 0.0 { depth } else { -depth };
+        let axis = toward_sides.normalize_or_zero();
+        let mut planes = self.planes;
+        for plane in &mut planes {
+            plane.w += blocks * plane.truncate().dot(axis);
+        }
+        Frustum { planes }
+    }
+    /// The frustum of a camera-relative `view_proj`, for tests outside this module.
+    #[cfg(test)]
+    pub(crate) fn from_view_projection(view_proj: glam::Mat4) -> Frustum {
+        Frustum {
+            planes: super::frustum(view_proj),
+        }
+    }
+}
+#[cfg(test)]
+mod tests {
+    use super::{Frustum, Vec3};
+    use crate::gfx::world_projection;
+    use glam::Mat4;
+
+    const FOV: f32 = 70.0;
+    const ASPECT: f32 = 16.0 / 9.0;
+    const FAR: f32 = 512.0;
+    const EPS: f32 = 0.01;
+
+    fn looking_down_minus_z() -> Frustum {
+        Frustum::from_view_projection(world_projection(FOV, ASPECT, FAR))
+    }
+
+    fn tangents() -> (f32, f32) {
+        let up = (FOV / 2.0).to_radians().tan();
+        (up * ASPECT, up)
+    }
+
+    /// Each of the six planes of the unmoved frustum, a point just inside and one just outside,
+    /// from the field of view worked out by hand.
+    #[test]
+    fn a_point_is_inside_only_within_all_six_planes() {
+        let view = looking_down_minus_z();
+        let (tan_x, tan_y) = tangents();
+        let depth = 10.0;
+        let inside = [
+            Vec3::new(0.0, 0.0, -depth),
+            Vec3::new(depth * tan_x - EPS, 0.0, -depth),
+            Vec3::new(-(depth * tan_x - EPS), 0.0, -depth),
+            Vec3::new(0.0, depth * tan_y - EPS, -depth),
+            Vec3::new(0.0, -(depth * tan_y - EPS), -depth),
+            Vec3::new(0.0, 0.0, -0.06),
+            Vec3::new(0.0, 0.0, -(FAR - 0.1)),
+        ];
+        let outside = [
+            Vec3::new(depth * tan_x + EPS, 0.0, -depth),
+            Vec3::new(-(depth * tan_x + EPS), 0.0, -depth),
+            Vec3::new(0.0, depth * tan_y + EPS, -depth),
+            Vec3::new(0.0, -(depth * tan_y + EPS), -depth),
+            Vec3::new(0.0, 0.0, -0.04),
+            Vec3::new(0.0, 0.0, -(FAR + 0.1)),
+            Vec3::new(0.0, 0.0, 1.0),
+            Vec3::new(0.0, 0.0, 0.0),
+        ];
+        for p in inside {
+            assert!(view.contains_point(p), "{p} should be inside");
+        }
+        for p in outside {
+            assert!(!view.contains_point(p), "{p} should be outside");
+        }
+        assert!(view.contains_point(Vec3::NAN), "an unknown point is kept");
+    }
+
+    /// Camera 3 blocks back: its apex is at z = 3, so the sides open by 3 * tan, the near
+    /// plane is at z = 3 - 0.05 and the far plane at z = 3 - FAR.
+    #[test]
+    fn pulling_the_camera_back_moves_every_plane() {
+        let (tan_x, tan_y) = tangents();
+        let back = looking_down_minus_z().pulled_back(3.0);
+        let inside = [
+            Vec3::new(0.0, 0.0, 2.9),
+            Vec3::new(3.0 * tan_x - EPS, 0.0, 0.0),
+            Vec3::new(-(3.0 * tan_x - EPS), 0.0, 0.0),
+            Vec3::new(0.0, 3.0 * tan_y - EPS, 0.0),
+            Vec3::new(0.0, -(3.0 * tan_y - EPS), 0.0),
+            Vec3::new(0.0, 0.0, 3.0 - FAR + 0.1),
+        ];
+        let outside = [
+            Vec3::new(0.0, 0.0, 3.0),
+            Vec3::new(3.0 * tan_x + EPS, 0.0, 0.0),
+            Vec3::new(-(3.0 * tan_x + EPS), 0.0, 0.0),
+            Vec3::new(0.0, 3.0 * tan_y + EPS, 0.0),
+            Vec3::new(0.0, -(3.0 * tan_y + EPS), 0.0),
+            Vec3::new(0.0, 0.0, 3.0 - FAR - 0.1),
+        ];
+        for p in inside {
+            assert!(back.contains_point(p), "{p} should be inside");
+        }
+        for p in outside {
+            assert!(!back.contains_point(p), "{p} should be outside");
+        }
+        // The unmoved frustum does not have the point that only the offset one has.
+        assert!(!looking_down_minus_z().contains_point(Vec3::new(0.0, 0.0, 2.9)));
+        // An offset of nothing changes no verdict.
+        let same = looking_down_minus_z();
+        let unmoved = same.pulled_back(0.0);
+        for p in [
+            Vec3::new(1.0, 2.0, -3.0),
+            Vec3::new(0.0, 0.0, 1.0),
+            Vec3::new(40.0, 0.0, -5.0),
+        ] {
+            assert_eq!(same.contains_point(p), unmoved.contains_point(p));
+        }
+    }
+
+    /// The offset follows the camera's own view direction, whatever way it looks.
+    #[test]
+    fn the_offset_is_along_the_view_direction() {
+        for (yaw, pitch) in [(0.3_f32, 0.0_f32), (2.0, -0.5), (-1.2, 0.9), (3.0, 1.2)] {
+            let pose = Mat4::from_rotation_x(pitch) * Mat4::from_rotation_y(yaw);
+            let view = Frustum::from_view_projection(world_projection(FOV, ASPECT, FAR) * pose);
+            let forward = pose.inverse().transform_vector3(-Vec3::Z);
+            let back = view.pulled_back(3.0);
+            assert!(
+                back.contains_point(forward * -2.9),
+                "{yaw} {pitch}: 2.9 behind"
+            );
+            assert!(
+                !back.contains_point(forward * -3.0),
+                "{yaw} {pitch}: 3 behind"
+            );
+            assert!(
+                !view.contains_point(forward * -2.9),
+                "{yaw} {pitch}: unmoved"
+            );
+            assert!(back.contains_point(forward * 20.0) && view.contains_point(forward * 20.0));
+        }
+    }
+
+    /// An orthographic box has no apex to pull back from: its side normals cancel, so there is
+    /// no direction, and the frustum must come back as it was.
+    #[test]
+    fn an_orthographic_frustum_stays_where_it_is() {
+        let ortho =
+            Frustum::from_view_projection(Mat4::orthographic_rh(-8.0, 8.0, -4.5, 4.5, 100.0, 0.05));
+        let moved = ortho.pulled_back(3.0);
+        for p in [
+            Vec3::new(0.0, 0.0, 2.0),
+            Vec3::new(0.0, 0.0, -9.0),
+            Vec3::new(7.9, 4.4, -9.0),
+            Vec3::new(8.1, 0.0, -9.0),
+            Vec3::new(0.0, 0.0, -101.0),
+        ] {
+            assert_eq!(ortho.contains_point(p), moved.contains_point(p), "{p}");
+        }
+    }
+
+    /// The shadow pass's box has no depth planes, so no direction: it must not move.
+    #[test]
+    fn a_frustum_without_depth_planes_stays_where_it_is() {
+        let mut flat = looking_down_minus_z();
+        flat.planes[4] = glam::Vec4::W;
+        flat.planes[5] = glam::Vec4::W;
+        let moved = flat.pulled_back(3.0);
+        for p in [
+            Vec3::new(0.0, 0.0, 2.0),
+            Vec3::new(0.0, 0.0, -9.0),
+            Vec3::new(80.0, 0.0, -9.0),
+        ] {
+            assert_eq!(flat.contains_point(p), moved.contains_point(p));
+        }
+    }
+}

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

@@ -853,7 +853,7 @@ impl H {
     fn label(self, s: &Settings, out: &EffectiveOutput) -> Text {
         let g = &s.horizon;
         match self {
-            H::Preset => labelled("Preset", g.preset.label()),
+            H::Preset => labelled("Horizon Preset", g.preset.label()),
             H::LodDistance => match g.lod_distance {
                 0 => labelled("LOD Distance", "Off"),
                 n => labelled("LOD Distance", lang::tr("%s chunks", &[&n])),
@@ -1753,6 +1753,14 @@ mod tests {
         ui.set_search("tearing");
         let found = ui.listed(&s, SIZE);
         assert!(found.iter().any(|(_, i)| *i == Item::Vanilla(Opt::Vsync)));
+        // Both presets answer "preset"; Horizon's own, named apart from vanilla's, answers its name.
+        ui.set_search("preset");
+        let found = ui.listed(&s, SIZE);
+        let general = |item| (Page::General, item);
+        assert!(found.contains(&general(Item::Horizon(H::Preset))));
+        assert!(found.contains(&general(Item::Vanilla(Opt::Preset))));
+        ui.set_search("horizon preset");
+        assert_eq!(ui.listed(&s, SIZE), [general(Item::Horizon(H::Preset))]);
         ui.set_search("hdr");
         let [x, y, w, h] = cols.page(Page::ALL.len() - 1);
         press(&mut ui, &mut s, (x + w / 2.0, y + h / 2.0));

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

@@ -55,7 +55,7 @@ pub struct TextureFlags {
 impl TextureFlags {
     /// The `texture` section of a `.png.mcmeta` file, if it sets either flag.
     pub fn from_mcmeta(json: &str) -> Option<Self> {
-        let meta = crate::packs::first_json(json.as_bytes())?;
+        let meta: serde_json::Value = crate::packs::first_json(json.as_bytes()).ok()?;
         let section = meta.get("texture")?;
         let flag = |key| section.get(key).and_then(serde_json::Value::as_bool) == Some(true);
         let flags = Self {
@@ -388,7 +388,7 @@ fn strip_frame(pixels: &[u8], stride: u32, x: u32, y: u32, w: u32, h: u32) -> Ve
 }
 /// The `animation` section of a texture's `.mcmeta`.
 fn animation_of(mcmeta: Option<&str>) -> Option<AnimationMetadata> {
-    let meta = crate::packs::first_json(mcmeta?.as_bytes())?;
+    let meta: serde_json::Value = crate::packs::first_json(mcmeta?.as_bytes()).ok()?;
     AnimationMetadata::from_json(&meta.get("animation")?.to_string()).ok()
 }
 /// An animated strip's first frame: the region the mcmeta's frame size picks

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

@@ -1594,9 +1594,9 @@ pub struct OptionsUi {
     radial_pick: shell::Shell<crate::radial_editor::PickScreen>,
     /// Shaders: the shader packs and the picked one's options, on the settings shell.
     shader: shell::Shell<crate::shader_ui::ShaderScreen>,
-    /// The Pack Options page, and the packs' Polytone config entries by pack id (the game
-    /// fills them beside `pack_infos`).
-    pub pack_options: crate::pack_options_ui::PackOptionsUi,
+    /// Pack Options, on the settings shell, and the packs' Polytone config entries by pack id
+    /// (the game fills them beside `pack_infos`).
+    pack_options: shell::Shell<crate::pack_options_ui::PackOptionsScreen>,
     pub pack_configs: std::collections::BTreeMap<String, horizon_polytone::pack::Configs>,
     pub split_profiles: crate::split_profiles::SplitProfiles,
     /// HDR calibration while its page is open.
@@ -3401,10 +3401,6 @@ impl OptionsUi {
             c.draw(batch, atlas, cursor);
             return;
         }
-        if self.page() == Page::PackOptions {
-            self.pack_options.draw(batch, atlas, cursor, self.in_world);
-            return;
-        }
         let waiting = self.waiting();
         let in_world = self.in_world;
         if self.draw_radial_name(batch, atlas, cursor, in_world) {
@@ -3786,20 +3782,6 @@ impl OptionsUi {
             });
             return self.shell_events(s, outputs);
         }
-        if self.page() == Page::PackOptions {
-            let mut events = Vec::new();
-            for action in self
-                .pack_options
-                .click((x, y), size, drag, right || self.shift)
-            {
-                match action {
-                    crate::pack_options_ui::Action::ButtonClick => events.push(Event::ButtonClick),
-                    crate::pack_options_ui::Action::SliderDrag => {}
-                    crate::pack_options_ui::Action::Done => events.extend(self.back(s)),
-                }
-            }
-            return events;
-        }
         if self.page() == Page::Packs {
             let mut events = Vec::new();
             if drag {
@@ -3829,14 +3811,7 @@ impl OptionsUi {
                 crate::pack_screen::Action::BrowsePick(i) => {
                     events.push(Event::DownloadPack(i));
                 }
-                crate::pack_screen::Action::Options(id) => {
-                    let mut configs = horizon_polytone::pack::Configs::default();
-                    if let Some(own) = self.pack_configs.get(&id) {
-                        configs.merge(own);
-                    }
-                    self.pack_options = crate::pack_options_ui::PackOptionsUi::open(configs);
-                    self.push(Page::PackOptions);
-                }
+                crate::pack_screen::Action::Options(id) => self.open_pack_options(&id),
                 crate::pack_screen::Action::None => {}
             }
             return events;
@@ -4074,7 +4049,6 @@ impl OptionsUi {
         // release, even if the pointer has left the widget or its value stayed.
         let slider = self.dragging.take().is_some();
         let shell_slider = self.shell_mut().and_then(|shell| shell.release());
-        self.pack_options.release();
         let calibration_slider = self.calibration.as_mut().is_some_and(|c| c.release());
         let split_drop = self.split_setup.release();
         if slider || shell_slider.is_some() || calibration_slider {
@@ -4168,10 +4142,6 @@ impl OptionsUi {
             self.studio.wheel(amount);
             return Vec::new();
         }
-        if self.page() == Page::PackOptions {
-            self.pack_options.scroll(size, amount);
-            return Vec::new();
-        }
         let plain = self.resource_error.is_none()
             && !(self.pack_screen.is_some() && self.stack.last() == Some(&Page::Packs));
         if !plain {
@@ -4255,10 +4225,6 @@ impl OptionsUi {
             self.studio.wheel(amount);
             return;
         }
-        if self.page() == Page::PackOptions {
-            self.pack_options.scroll(size, amount);
-            return;
-        }
         match &mut self.pack_screen {
             Some(p) if self.stack.last() == Some(&Page::Packs) => {
                 p.scroll(cursor.0 as f64, cursor.1 as f64, amount as f64)
@@ -4393,14 +4359,8 @@ impl OptionsUi {
         self.can_change_value = false;
         match page {
             Page::PackOptions => {
-                let ui = std::mem::take(&mut self.pack_options);
-                if ui.changed {
-                    let entries = ui.configs.entries().keys().cloned().collect();
-                    events.push(Event::PackOptions {
-                        entries,
-                        chosen: ui.configs.chosen(),
-                    });
-                }
+                let screen = std::mem::take(&mut self.pack_options.screen);
+                events.extend(screen.finished());
             }
             Page::ShaderOptions | Page::ShaderPacks => {
                 if s.shader_options.as_ref().is_some_and(|o| o.changed) {
@@ -4960,6 +4920,34 @@ mod tests {
     /// A renderer whose destination offers nothing and whose display reports nothing.
     const NONE: EffectiveOutput = EffectiveOutput::NONE;
 
+    #[test]
+    fn pack_options_leave_with_a_change_and_with_nothing_after_its_undo() {
+        use crate::settings_shell::Screen as _;
+        let mut s = Settings::default();
+        let atlas = HudAtlas::build(std::path::Path::new("/nonexistent/horizon-test-assets"));
+        let atlas = atlas.unwrap();
+        let mut ui = OptionsUi::default();
+        let mut configs = horizon_polytone::pack::Configs::default();
+        let birds = serde_json::json!({"default_value": true});
+        configs.add_entry("p:birds".into(), &birds);
+        ui.pack_configs.insert("pack".into(), configs);
+        for undone in [false, true] {
+            ui.open_pack_options("pack");
+            assert!(ui.shell().is_some(), "Pack Options is on the shell");
+            let birds = crate::pack_options_ui::Item::Entry(0);
+            ui.pack_options.screen.press(&mut s, birds, false);
+            if undone {
+                let before = s.clone();
+                ui.pack_options.screen.undo(&mut s, &before);
+            }
+            let events = ui.key(&mut s, &atlas, winit::keyboard::KeyCode::Escape, None);
+            let sent = events
+                .iter()
+                .any(|e| matches!(e, Event::PackOptions { .. }));
+            assert_eq!(sent, !undone, "undone: {undone}");
+        }
+    }
+
     /// The window allows the input method only while `typing` says a search
     /// box has the focus (`Game::text_field_focused`), so a page without one
     /// must not claim the keys: the movement and menu keys keep working there.

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

@@ -23,6 +23,7 @@ impl OptionsUi {
             Page::ControllerRadialPick => Some(&self.radial_pick),
             page if Self::controller_page(page).is_some() => Some(&self.controller),
             page if Self::shader_page(page).is_some() => Some(&self.shader),
+            Page::PackOptions => Some(&self.pack_options),
             _ => None,
         }
     }
@@ -35,9 +36,20 @@ impl OptionsUi {
             Page::ControllerRadialPick => Some(&mut self.radial_pick),
             page if Self::controller_page(page).is_some() => Some(&mut self.controller),
             page if Self::shader_page(page).is_some() => Some(&mut self.shader),
+            Page::PackOptions => Some(&mut self.pack_options),
             _ => None,
         }
     }
+    /// Pack Options for the pack `id`, from the pack screen: its Polytone config entries.
+    pub(super) fn open_pack_options(&mut self, id: &str) {
+        let mut configs = horizon_polytone::pack::Configs::default();
+        if let Some(own) = self.pack_configs.get(id) {
+            configs.merge(own);
+        }
+        // Opening a shell starts it afresh: the entries go in after.
+        self.push(Page::PackOptions);
+        self.pack_options.screen = crate::pack_options_ui::PackOptionsScreen::open(configs);
+    }
     /// Where the open shell screen asked the focus to open (a radial slot's list, on the slot's
     /// action), for a controller's focus to land there.
     pub fn shell_opened_focus(&self) -> Option<[f32; 4]> {
@@ -53,13 +65,14 @@ impl OptionsUi {
             return;
         }
         // Every shell: the click may have changed the page.
-        let shells: [&mut dyn shell::Hosted; 6] = [
+        let shells: [&mut dyn shell::Hosted; 7] = [
             &mut self.extras,
             &mut self.graphics,
             &mut self.controller,
             &mut self.radial,
             &mut self.radial_pick,
             &mut self.shader,
+            &mut self.pack_options,
         ];
         for shell in shells {
             shell.clicks_step(false);

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

@@ -1,45 +1,36 @@
-//! The Pack Options page (#11486): the config entries of the selected resource packs' Polytone
-//! `config_entries` (wiki "Polytone Configs"), in the frame of Horizon's settings screens
-//! (`settings_shell`). Numbers are sliders, texts cycle, booleans switch; the entries sit in
-//! their `section`s, named by the packs' own translations. Leaving with Done keeps what changed,
-//! and the packs load again with it.
-use crate::widgets::Action as Declared;
+//! The Pack Options screen (#11486), on the settings shell (`settings_shell`): the config entries
+//! of the selected resource packs' Polytone `config_entries` (wiki "Polytone Configs"). Each
+//! `section` is a page, named by the packs' own translations; numbers are sliders that stop at
+//! the entry's `step`, value lists are choices, booleans switch and free text reads. The first
+//! page starts with the pack-wide presets and Reset all. The shell gives it the keyboard, a
+//! controller's focus, the search, the strip's descriptions and Undo; leaving keeps what differs
+//! from how the screen opened, and the packs load again with it.
 use crate::{
-    graphics_style as style,
-    hud::{HudAtlas, HudBatch},
     lang,
-    settings_shell::{self as shell, Columns, Line, Lines},
-    text::Text,
-    ui,
+    settings::Settings,
+    settings_shell::{self as shell, Group, Output, Row, Sheet, Value},
 };
 use horizon_polytone::pack::{ConfigKind, ConfigValue, Configs};
 
-/// What a click asks of the options screen.
+/// A row: the pack-wide presets, Reset all, or the entry at an index of `ids`.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum Action {
-    ButtonClick,
-    SliderDrag,
-    /// Done: leave, keeping what changed.
-    Done,
+pub(crate) enum Item {
+    Presets,
+    ResetAll,
+    Entry(u16),
 }
 
-/// The page's state: the entries being edited, how they are listed, and the pointer's hold.
-#[derive(Default)]
-pub struct PackOptionsUi {
-    /// The selected packs' entries and the values being picked.
-    pub configs: Configs,
-    /// Entry ids, by the row index the list uses.
-    ids: Vec<String>,
-    /// The sections in order: the `section` id (none for entries without one) and its rows.
-    sections: Vec<(Option<String>, Vec<u16>)>,
-    scroll: ui::Scroll,
-    dragging: Option<u16>,
-    /// A value changed since the page opened.
-    pub changed: bool,
-}
-
-/// The presets' row (and its section): past every entry's index.
-const PRESETS: u16 = u16::MAX;
+const TITLE: &str = "horizon.pack.options.title";
+/// The first page's group of rows for the whole pack, and every page's group of entries.
+const WHOLE_PACK: &str = "Whole pack";
+const PACK_OPTIONS: &str = "Pack settings";
+const RESET_ALL: &str = "Reset all";
+const RESET_ABOUT: &str = "Puts every option of this pack back to its default.";
+const AT_DEFAULTS: &str = "Every option is at its default already.";
+const PRESETS_ABOUT: &str = "Sets many options at once, as the pack groups them.";
+const PACK_SETTINGS: &str = "Settings made by the pack's author: they change only this pack.";
+/// A pack's tooltips, with the performance line after them, run longer than Horizon's own.
+const NOTE_LINES: usize = 3;
 
 /// A translation, or `fallback` where no language has the key.
 fn translated(key: &str, fallback: impl FnOnce() -> String) -> String {
@@ -65,9 +56,34 @@ fn readable(path: &str) -> String {
         .unwrap_or_default()
 }
 
-impl PackOptionsUi {
-    /// The page opens on `configs`, the selected packs' entries with the player's values.
-    pub fn open(configs: Configs) -> Self {
+/// A number as its entry shows it: whole with a whole step, else up to two decimals.
+fn number_text(n: f64, step: f64) -> String {
+    if step >= 1.0 && step.fract() == 0.0 {
+        format!("{n:.0}")
+    } else {
+        let text = format!("{n:.2}");
+        text.trim_end_matches('0').trim_end_matches('.').to_owned()
+    }
+}
+
+/// The screen: the entries being edited, as they were when it opened (for Undo and for whether
+/// leaving changes anything), and how they are paged.
+#[derive(Default)]
+pub(crate) struct PackOptionsScreen {
+    /// The selected packs' entries and the values being picked.
+    pub(crate) configs: Configs,
+    opened: Configs,
+    /// Entry ids, by `Item::Entry`'s index.
+    ids: Vec<String>,
+    /// The sections in order: the `section` id (none for entries without one) and its entries.
+    sections: Vec<(Option<String>, Vec<u16>)>,
+    /// Bumped on every change, for `stamp`: the values are floats, which don't hash.
+    revision: u64,
+}
+
+impl PackOptionsScreen {
+    /// The screen opens on `configs`, the selected packs' entries with the player's values.
+    pub(crate) fn open(configs: Configs) -> Self {
         let mut ids: Vec<(String, Option<String>, i64)> = configs
             .entries()
             .iter()
@@ -96,25 +112,21 @@ impl PackOptionsUi {
             (None, None) => a.0.cmp(&b.0),
         });
         Self {
+            opened: configs.clone(),
             configs,
             ids: ids.into_iter().map(|(id, ..)| id).collect(),
             sections: sections.into_iter().map(|(s, _, rows)| (s, rows)).collect(),
-            ..Self::default()
+            revision: 0,
         }
     }
 
-    fn layout(&self, w: f32, h: f32) -> (Columns, Vec<Line<u16, u16>>, f32) {
-        let cols = Columns::of(w, h);
-        let mut lines = Lines::new();
-        // The pack-wide presets first, when the entries have some.
-        if !self.configs.presets().is_empty() {
-            lines.titled(PRESETS, vec![PRESETS]);
-        }
-        for (i, (_, rows)) in self.sections.iter().enumerate() {
-            lines.titled(i as u16, rows.clone());
-        }
-        let (lines, content) = lines.finish();
-        (cols, lines, content)
+    /// What leaving sends: the entries and the player's choices, if they differ from how the
+    /// screen opened (an Undo, or a value stepped back, leaves nothing to send).
+    pub(crate) fn finished(&self) -> Option<crate::options_ui::Event> {
+        (self.configs != self.opened).then(|| crate::options_ui::Event::PackOptions {
+            entries: self.configs.entries().keys().cloned().collect(),
+            chosen: self.configs.chosen(),
+        })
     }
 
     /// The namespace the presets' translations are under: of the first entry with presets.
@@ -166,21 +178,14 @@ impl PackOptionsUi {
             None if back => n - 1,
             None => 0,
         };
-        let before = self.configs.clone();
         self.configs.apply_preset(&presets[next]);
-        if self.configs != before {
-            self.changed = true;
-        }
+        self.revision += 1;
     }
 
-    /// A section's heading: `config.<namespace>.section.<id>`, by its first entry's namespace.
-    fn section_name(&self, section: u16) -> String {
-        if section == PRESETS {
-            let key = format!("{}.presets", self.presets_namespace());
-            return translated(&key, || lang::get("horizon.pack.options.presets"));
-        }
-        let Some((id, rows)) = self.sections.get(usize::from(section)) else {
-            return String::new();
+    /// A section's page name: `config.<namespace>.section.<id>`, by its first entry's namespace.
+    fn section_name(&self, section: usize) -> String {
+        let Some((id, rows)) = self.sections.get(section) else {
+            return lang::get("horizon.pack.options.general");
         };
         let Some(id) = id else {
             return lang::get("horizon.pack.options.general");
@@ -192,367 +197,218 @@ impl PackOptionsUi {
         translated(&format!("config.{namespace}.section.{id}"), || readable(id))
     }
 
-    /// An entry's name (`config.<namespace>.<name>`) and its value's label.
-    fn parts(&self, row: u16) -> (String, Option<String>) {
-        if row == PRESETS {
-            let label = self.preset_label(self.current_preset().as_deref());
-            return (self.section_name(PRESETS), Some(label));
-        }
-        let Some(id) = self.ids.get(usize::from(row)) else {
-            return (String::new(), None);
-        };
-        let (namespace, path) = split(id);
-        let name = translated(&format!("config.{namespace}.{path}"), || readable(path));
-        let entry = &self.configs.entries()[id];
-        let value = match self.configs.get(id) {
-            Some(ConfigValue::Number(n)) => {
-                let step = match entry.kind {
-                    ConfigKind::Number { step, .. } => step,
-                    _ => 1.0,
-                };
-                let text = if step >= 1.0 && step.fract() == 0.0 {
-                    format!("{n:.0}")
-                } else {
-                    format!("{n:.2}")
-                        .trim_end_matches('0')
-                        .trim_end_matches('.')
-                        .to_owned()
-                };
-                Some(text)
-            }
-            Some(ConfigValue::Text(t)) => Some(t.clone()),
-            Some(ConfigValue::Bool(_)) | None => None,
-        };
-        let value = value.map(|v| match &entry.value_translation {
-            Some(key) if lang::has(key) => lang::tr(key, &[&v]),
-            _ => v,
-        });
-        (name, value)
-    }
-
-    /// The tooltip (`config.<namespace>.<name>.tooltip`) and the performance hint.
-    fn description(&self, row: u16) -> String {
-        let Some(id) = self.ids.get(usize::from(row)) else {
-            return String::new();
-        };
+    /// The tooltip (`config.<namespace>.<name>.tooltip`) and the performance line after it.
+    fn description(&self, id: &str) -> String {
         let (namespace, path) = split(id);
         let key = format!("config.{namespace}.{path}.tooltip");
-        let mut text = if lang::has(&key) {
+        let tooltip = if lang::has(&key) {
             lang::get(&key)
         } else {
             String::new()
         };
-        if let Some(impact) = &self.configs.entries()[id].performance_impact {
-            let level = lang::get(&format!("horizon.pack.options.impact.{impact}"));
-            let line = lang::tr("horizon.pack.options.impact", &[&level]);
-            text = if text.is_empty() {
-                line
-            } else {
-                format!("{text} {line}")
-            };
-        }
-        text
-    }
-
-    /// A slider's place (0 to 1) for a number entry.
-    fn slider(&self, row: u16) -> Option<f32> {
-        let id = self.ids.get(usize::from(row))?;
-        let ConfigKind::Number { min, max, .. } = self.configs.entries()[id].kind else {
-            return None;
-        };
-        let Some(ConfigValue::Number(n)) = self.configs.get(id) else {
-            return None;
-        };
-        Some(if max > min {
-            ((n - min) / (max - min)) as f32
-        } else {
-            0.0
-        })
-    }
-
-    fn switch(&self, row: u16) -> Option<bool> {
-        match self.configs.get(self.ids.get(usize::from(row))?)? {
-            ConfigValue::Bool(b) => Some(*b),
-            _ => None,
+        let impact = self.configs.entries()[id]
+            .performance_impact
+            .as_ref()
+            .map(|impact| {
+                let level = lang::get(&format!("horizon.pack.options.impact.{impact}"));
+                lang::tr("horizon.pack.options.impact", &[&level])
+            });
+        match impact {
+            Some(line) if tooltip.is_empty() => line,
+            Some(line) => format!("{tooltip} {line}"),
+            None => tooltip,
         }
     }
 
-    pub fn draw(
-        &mut self,
-        batch: &mut HudBatch,
-        atlas: &HudAtlas,
-        cursor: (f32, f32),
-        in_world: bool,
-    ) {
-        let (w, h) = (batch.width, batch.height);
-        let (cols, lines, content) = self.layout(w, h);
-        self.scroll.clamp(cols.top, cols.bottom, content);
-        shell::backdrop(batch, atlas, in_world);
-        shell::mark(
-            batch,
-            atlas,
-            &cols,
-            &lang::get("horizon.pack.options.title"),
-        );
-        shell::plate(
-            batch,
-            atlas,
-            &cols,
-            &lang::get("horizon.pack.options.title"),
-        );
-        let over_list = cursor.1 >= cols.top && cursor.1 < cols.bottom;
-        let mut described = None;
-        shell::list(
-            batch,
-            atlas,
-            &cols,
-            &lines,
-            self.scroll.amount,
-            |section| self.section_name(section),
-            |batch, row: u16, y| {
-                let [rx, ry, rw, rh] = cols.row(y);
-                let hover = over_list && ui::hovered(cursor, rx, ry, rw, rh);
-                if hover || self.dragging == Some(row) {
-                    described = Some(row);
+    /// Entry `i`'s row: a switch, a slider in its steps, a choice, or text to read.
+    fn entry_row(&self, i: u16) -> Option<Row<Item>> {
+        let id = self.ids.get(usize::from(i))?;
+        let (namespace, path) = split(id);
+        let name = translated(&format!("config.{namespace}.{path}"), || readable(path));
+        let entry = &self.configs.entries()[id];
+        let shown = |text: String| match &entry.value_translation {
+            Some(key) if lang::has(key) => lang::tr(key, &[&text]),
+            _ => text,
+        };
+        let value = match (&entry.kind, self.configs.get(id)?) {
+            (_, ConfigValue::Bool(on)) => Value::Switch(*on),
+            (&ConfigKind::Number { min, max, step }, &ConfigValue::Number(n)) => {
+                let span = max - min;
+                let stops = if step > 0.0 {
+                    (span / step).round()
+                } else {
+                    0.0
+                };
+                Value::Slider {
+                    position: if span > 0.0 {
+                        ((n - min) / span) as f32
+                    } else {
+                        0.0
+                    },
+                    steps: (stops >= 1.0).then_some(stops as u32),
+                    text: shown(number_text(n, step)),
                 }
-                let (name, value) = self.parts(row);
-                let label = match &value {
-                    Some(v) => format!("{name}: {v}"),
-                    None => name.clone(),
-                };
-                let view = shell::RowView {
-                    label: &label,
-                    name: &name,
-                    value: value.as_deref(),
-                    switch: self.switch(row),
-                    slider: self.slider(row),
-                    live: true,
-                    hover,
-                    focused: false,
-                    held: self.dragging == Some(row),
-                    key: None,
-                };
-                shell::row(batch, atlas, &cols, y, &view);
-            },
-        );
-        shell::scroller(batch, atlas, &cols, content, self.scroll.amount);
-        // The strip: the pointed-at entry's tooltip.
-        let [x, y, ..] = cols.dock;
-        style::panel(batch, atlas, cols.dock);
-        if let Some(row) = described {
-            let name = Text::literal(self.parts(row).0);
-            batch.text_styled(atlas, &name, x + 12.0, y + 8.0, style::WHITE, true);
-            shell::dock_note(batch, atlas, &cols, self.description(row), style::GREY);
-        }
-        let mut foot = vec![(cols.button(0), "gui.done", Some(Declared::Done))];
-        if self
-            .configs
-            .chosen()
-            .iter()
-            .any(|(id, _)| self.ids.contains(id))
-        {
-            foot.push((cols.button(1), "controls.reset", None));
-        }
-        for (rect, key, declared) in foot {
-            if let Some(declared) = declared {
-                crate::widgets::declare_action(declared, rect, true);
             }
-            let label = Text::literal(lang::get(key));
-            shell::foot_button(batch, atlas, rect, &label, cursor, (false, true));
-        }
+            (ConfigKind::Text { allowed }, ConfigValue::Text(t)) if !allowed.is_empty() => {
+                Value::Choice(shown(t.clone()))
+            }
+            (_, value) => Value::Read(shown(match value {
+                ConfigValue::Number(n) => number_text(*n, 1.0),
+                ConfigValue::Text(t) => t.clone(),
+                ConfigValue::Bool(b) => b.to_string(),
+            })),
+        };
+        Some(Row::new(Item::Entry(i), name, value).about(self.description(id)))
     }
 
-    /// A press (or a drag with `drag`) at `(x, y)`; `back` turns a cycle backwards.
-    pub fn click(
-        &mut self,
-        (x, y): (f32, f32),
-        (w, h): (f32, f32),
-        drag: bool,
-        back: bool,
-    ) -> Vec<Action> {
-        let (cols, lines, content) = self.layout(w, h);
-        let at = |[rx, ry, rw, rh]: [f32; 4]| ui::hovered((x, y), rx, ry, rw, rh);
-        if drag {
-            if self.scroll.held() {
-                self.scroll.drag(y, cols.top, cols.bottom, content);
-            } else if let Some(row) = self.dragging {
-                self.set_slider(row, cols.slider_at(x));
-                return vec![Action::SliderDrag];
-            }
-            return Vec::new();
+    /// The rows for the whole pack: its presets, when it has some, and Reset all.
+    fn whole_pack(&self) -> Group<Item> {
+        let mut rows = Vec::new();
+        if !self.configs.presets().is_empty() {
+            let key = format!("{}.presets", self.presets_namespace());
+            let name = translated(&key, || lang::get("horizon.pack.options.presets"));
+            let label = self.preset_label(self.current_preset().as_deref());
+            rows.push(
+                Row::new(Item::Presets, name, Value::Choice(label)).about(lang::get(PRESETS_ABOUT)),
+            );
         }
-        if cols.scrolls()
-            && self
-                .scroll
-                .press((x, y), cols.bar_x(), cols.top, cols.bottom, content)
-        {
-            return Vec::new();
+        let at_defaults = self.configs.chosen().is_empty();
+        let reset = Row::new(Item::ResetAll, lang::get(RESET_ALL), Value::Press)
+            .about(lang::get(RESET_ABOUT))
+            .blocked(at_defaults.then(|| lang::get(AT_DEFAULTS)));
+        rows.push(reset);
+        Group {
+            name: WHOLE_PACK,
+            rows,
         }
-        if at(cols.button(0)) {
-            return vec![Action::ButtonClick, Action::Done];
-        }
-        if at(cols.button(1)) {
-            self.reset();
-            return vec![Action::ButtonClick];
-        }
-        if y < cols.top || y >= cols.bottom {
-            return Vec::new();
-        }
-        let Some(row) = lines.iter().find_map(|line| {
-            let row = line.setting?;
-            at(cols.row(cols.top + line.y - self.scroll.amount)).then_some(row)
-        }) else {
-            return Vec::new();
-        };
-        if row == PRESETS {
-            self.cycle_preset(back);
-            return vec![Action::ButtonClick];
-        }
-        let Some(id) = self.ids.get(usize::from(row)).cloned() else {
-            return Vec::new();
-        };
-        let entry = self.configs.entries()[&id].clone();
-        match (&entry.kind, self.configs.get(&id).cloned()) {
-            (ConfigKind::Number { .. }, _) => {
-                self.dragging = Some(row);
-                self.set_slider(row, cols.slider_at(x));
-                return vec![Action::SliderDrag];
-            }
-            (ConfigKind::Bool, Some(ConfigValue::Bool(b))) => {
-                self.set(&id, ConfigValue::Bool(!b));
-            }
-            (ConfigKind::Text { allowed }, Some(ConfigValue::Text(t))) if !allowed.is_empty() => {
-                let i = allowed.iter().position(|a| *a == t).unwrap_or(0);
-                let n = allowed.len();
-                let next = if back { (i + n - 1) % n } else { (i + 1) % n };
-                self.set(&id, ConfigValue::Text(allowed[next].clone()));
-            }
-            _ => return Vec::new(),
-        }
-        vec![Action::ButtonClick]
     }
 
     fn set(&mut self, id: &str, value: ConfigValue) {
-        let before = self.configs.get(id).cloned();
         self.configs.set(id, value);
-        if self.configs.get(id).cloned() != before {
-            self.changed = true;
-        }
-    }
-
-    /// Number entry `row` at slider place `at` (0 to 1).
-    fn set_slider(&mut self, row: u16, at: f32) {
-        let Some(id) = self.ids.get(usize::from(row)).cloned() else {
-            return;
-        };
-        if let ConfigKind::Number { min, max, .. } = self.configs.entries()[&id].kind {
-            self.set(&id, ConfigValue::Number(min + f64::from(at) * (max - min)));
-        }
+        self.revision += 1;
     }
 
     /// Every entry back to its default.
     fn reset(&mut self) {
-        let defaults: Vec<_> = self
-            .configs
-            .entries()
-            .iter()
+        let defaults: Vec<_> = (self.configs.entries().iter())
             .map(|(id, e)| (id.clone(), e.default.clone()))
             .collect();
         for (id, value) in defaults {
             self.set(&id, value);
         }
     }
+}
 
-    /// The pointer lets go.
-    pub fn release(&mut self) {
-        self.scroll.release();
-        self.dragging = None;
+impl shell::Screen for PackOptionsScreen {
+    type Page = u16;
+    type Row = Item;
+    fn title(&self) -> &'static str {
+        TITLE
     }
-
-    /// The mouse wheel scrolls the list.
-    pub fn scroll(&mut self, (w, h): (f32, f32), amount: f32) {
-        let (cols, _, content) = self.layout(w, h);
-        self.scroll
-            .wheel(amount, 18.0, cols.top, cols.bottom, content);
+    fn note_lines(&self) -> usize {
+        NOTE_LINES
+    }
+    /// The rows read only the screen's own entries, which change through it alone.
+    fn stamp(&self, _s: &Settings) -> u64 {
+        self.revision
+    }
+    /// A page per section; the first starts with the rows for the whole pack.
+    fn sheets(&self, _s: &Settings) -> Vec<Sheet<u16, Item>> {
+        let about = lang::get(PACK_SETTINGS);
+        let mut sheets = Vec::new();
+        for (i, (_, entries)) in self.sections.iter().enumerate() {
+            let rows = entries.iter().filter_map(|&e| self.entry_row(e)).collect();
+            let mut groups = vec![Group {
+                name: PACK_OPTIONS,
+                rows,
+            }];
+            if i == 0 {
+                groups.insert(0, self.whole_pack());
+            }
+            sheets.push(Sheet::new(
+                i as u16,
+                self.section_name(i),
+                about.clone(),
+                groups,
+            ));
+        }
+        if sheets.is_empty() {
+            let groups = vec![self.whole_pack()];
+            sheets.push(Sheet::new(0, self.section_name(0), about, groups));
+        }
+        sheets
+    }
+    /// A switch flips, a choice and the presets step (back with Shift, or Left), Reset all
+    /// resets.
+    fn press(&mut self, _s: &mut Settings, item: Item, back: bool) -> Vec<Output> {
+        let i = match item {
+            Item::Presets => {
+                self.cycle_preset(back);
+                return Vec::new();
+            }
+            Item::ResetAll => {
+                self.reset();
+                return Vec::new();
+            }
+            Item::Entry(i) => i,
+        };
+        let Some(id) = self.ids.get(usize::from(i)).cloned() else {
+            return Vec::new();
+        };
+        let kind = self.configs.entries()[&id].kind.clone();
+        match (kind, self.configs.get(&id).cloned()) {
+            (_, Some(ConfigValue::Bool(on))) => self.set(&id, ConfigValue::Bool(!on)),
+            (ConfigKind::Text { allowed }, Some(ConfigValue::Text(t))) if !allowed.is_empty() => {
+                let at = allowed.iter().position(|a| *a == t).unwrap_or(0);
+                let n = allowed.len();
+                let next = if back { (at + n - 1) % n } else { (at + 1) % n };
+                self.set(&id, ConfigValue::Text(allowed[next].clone()));
+            }
+            _ => {}
+        }
+        Vec::new()
+    }
+    /// A slider moves its entry to the step nearest it (`Configs::set` snaps it).
+    fn slide(&mut self, _s: &mut Settings, item: Item, position: f32) {
+        let Item::Entry(i) = item else { return };
+        let Some(id) = self.ids.get(usize::from(i)).cloned() else {
+            return;
+        };
+        if let ConfigKind::Number { min, max, .. } = self.configs.entries()[&id].kind {
+            let value = min + f64::from(position.clamp(0.0, 1.0)) * (max - min);
+            self.set(&id, ConfigValue::Number(value));
+        }
+    }
+    /// With the "Scroll wheel changes settings" extra, the wheel steps a choice and the presets.
+    fn wheel_step(&mut self, s: &mut Settings, item: Item, back: bool) -> Option<Vec<Output>> {
+        let steps = match item {
+            Item::Presets => true,
+            Item::Entry(i) => self
+                .entry_row(i)
+                .is_some_and(|row| matches!(row.value, Value::Choice(_))),
+            Item::ResetAll => false,
+        };
+        if !steps {
+            return None;
+        }
+        let mut outputs = vec![Output::Event(crate::options_ui::Event::ButtonClick)];
+        outputs.extend(self.press(s, item, back));
+        Some(outputs)
+    }
+    fn undoes(&self) -> bool {
+        true
+    }
+    /// The entries as the screen opened with them.
+    fn undo(&mut self, _s: &mut Settings, _before: &Settings) -> Vec<Output> {
+        self.configs = self.opened.clone();
+        self.revision += 1;
+        Vec::new()
+    }
+    /// Undo shows exactly while an entry differs from how the screen opened.
+    fn differs(&self, _s: &Settings, _before: &Settings) -> Option<bool> {
+        Some(self.configs != self.opened)
     }
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-
-    fn configs() -> Configs {
-        let mut c = Configs::default();
-        c.add_entry(
-            "p:fog".into(),
-            &serde_json::json!({"default_value": 0.5, "section": "sky", "section_order": 2}),
-        );
-        c.add_entry("p:rain".into(), &serde_json::json!({"default_value": "drops", "allowed_values": ["drops", "streaks"], "section": "weather", "section_order": 1}));
-        c.add_entry(
-            "p:birds".into(),
-            &serde_json::json!({"default_value": true}),
-        );
-        c
-    }
-
-    #[test]
-    fn sections_sort_by_their_order_and_the_unsectioned_last() {
-        let ui = PackOptionsUi::open(configs());
-        let order: Vec<_> = ui.sections.iter().map(|(s, _)| s.as_deref()).collect();
-        assert_eq!(order, [Some("weather"), Some("sky"), None]);
-    }
-
-    #[test]
-    fn rows_switch_cycle_and_slide() {
-        let mut ui = PackOptionsUi::open(configs());
-        let size = (480.0, 270.0);
-        let (cols, lines, _) = ui.layout(size.0, size.1);
-        let ids = ui.ids.clone();
-        let point = |id: &str| {
-            let row = ids.iter().position(|i| i == id).unwrap() as u16;
-            let line = lines.iter().find(|l| l.setting == Some(row)).unwrap();
-            let [x, y, w, h] = cols.row(cols.top + line.y);
-            (x + w - 4.0, y + h / 2.0)
-        };
-        let (birds, rain) = (point("p:birds"), point("p:rain"));
-        ui.click(birds, size, false, false);
-        assert_eq!(ui.configs.get("p:birds"), Some(&ConfigValue::Bool(false)));
-        ui.click(rain, size, false, false);
-        assert_eq!(
-            ui.configs.get("p:rain"),
-            Some(&ConfigValue::Text("streaks".into()))
-        );
-        // The slider's far right end is its maximum.
-        let fog = point("p:fog");
-        let (tx, tw) = cols.track();
-        ui.click((tx + tw, fog.1), size, false, false);
-        ui.release();
-        assert_eq!(ui.configs.get("p:fog"), Some(&ConfigValue::Number(1.0)));
-        assert!(ui.changed);
-        assert_eq!(ui.configs.chosen().len(), 3);
-        ui.reset();
-        assert!(ui.configs.chosen().is_empty());
-    }
-
-    #[test]
-    fn the_presets_row_cycles_the_pack_wide_presets_and_shows_custom_otherwise() {
-        let mut c = Configs::default();
-        let entry = |default: f64, fast: f64, pretty: f64| serde_json::json!({"default_value": default, "presets": {"fast": fast, "pretty": pretty}});
-        c.add_entry("p:fog".into(), &entry(0.5, 0.0, 1.0));
-        c.add_entry("p:dust".into(), &entry(0.5, 0.0, 0.8));
-        let mut ui = PackOptionsUi::open(c);
-        // The defaults are no preset.
-        assert_eq!(ui.current_preset(), None);
-        ui.cycle_preset(false);
-        assert_eq!(ui.current_preset().as_deref(), Some("fast"));
-        assert_eq!(ui.configs.get("p:fog"), Some(&ConfigValue::Number(0.0)));
-        ui.cycle_preset(false);
-        assert_eq!(ui.current_preset().as_deref(), Some("pretty"));
-        ui.cycle_preset(true);
-        assert_eq!(ui.current_preset().as_deref(), Some("fast"));
-        // One value off the preset: custom again.
-        ui.set("p:dust", ConfigValue::Number(0.3));
-        assert_eq!(ui.current_preset(), None);
-        assert!(ui.changed);
-    }
-}
+mod tests;

crates/horizon-client-render/src/pack_options_ui/tests.rs

@@ -0,0 +1,281 @@
+use super::*;
+use crate::options_ui::Event;
+use crate::settings_shell::{Columns, Hosted, Screen as _, Shell, Target};
+use winit::keyboard::KeyCode as K;
+
+const SIZE: (f32, f32) = (854.0, 480.0);
+
+/// Fog (a number) under Sky, rain (a list of values) under Weather, birds (a boolean) in no
+/// section.
+fn configs() -> Configs {
+    let mut c = Configs::default();
+    c.add_entry(
+        "p:fog".into(),
+        &serde_json::json!({"default_value": 0.5, "section": "sky", "section_order": 2}),
+    );
+    c.add_entry("p:rain".into(), &serde_json::json!({"default_value": "drops", "allowed_values": ["drops", "streaks"], "section": "weather", "section_order": 1}));
+    c.add_entry(
+        "p:birds".into(),
+        &serde_json::json!({"default_value": true}),
+    );
+    c
+}
+
+/// Two entries with the pack-wide presets `fast` and `pretty`.
+fn with_presets() -> Configs {
+    let mut c = Configs::default();
+    let entry = |default: f64, fast: f64, pretty: f64| serde_json::json!({"default_value": default, "presets": {"fast": fast, "pretty": pretty}});
+    c.add_entry("p:fog".into(), &entry(0.5, 0.0, 1.0));
+    c.add_entry("p:dust".into(), &entry(0.5, 0.0, 0.8));
+    c
+}
+
+fn shell_of(configs: Configs) -> Shell<PackOptionsScreen> {
+    let mut shell = Shell::default();
+    shell.screen = PackOptionsScreen::open(configs);
+    shell
+}
+
+/// The row of entry `id`, and the page it is on.
+fn entry(shell: &Shell<PackOptionsScreen>, id: &str) -> (u16, Item) {
+    let i = shell.screen.ids.iter().position(|e| e == id).unwrap() as u16;
+    let page = shell.screen.sections.iter().position(|s| s.1.contains(&i));
+    (page.unwrap() as u16, Item::Entry(i))
+}
+
+fn press(shell: &mut Shell<PackOptionsScreen>, s: &mut Settings, item: Item) -> Vec<Output> {
+    let at = shell.point_at(s, SIZE, item);
+    shell.click(s, at, SIZE, false, false, false)
+}
+
+fn value<'a>(shell: &'a Shell<PackOptionsScreen>, id: &str) -> Option<&'a ConfigValue> {
+    shell.screen.configs.get(id)
+}
+
+#[test]
+fn sections_sort_by_their_order_and_the_unsectioned_last() {
+    let screen = PackOptionsScreen::open(configs());
+    let order: Vec<_> = screen.sections.iter().map(|(s, _)| s.as_deref()).collect();
+    assert_eq!(order, [Some("weather"), Some("sky"), None]);
+    // Each section is a page, the first one holding Reset all before its entries.
+    let sheets = screen.sheets(&Settings::default());
+    let names: Vec<_> = sheets.iter().map(|p| p.name.as_str()).collect();
+    assert_eq!(names, ["Weather", "Sky", "horizon.pack.options.general"]);
+    let first: Vec<Vec<Item>> = (sheets[0].groups.iter())
+        .map(|g| g.rows.iter().map(|r| r.id).collect())
+        .collect();
+    let rain = screen.ids.iter().position(|e| e == "p:rain").unwrap() as u16;
+    assert_eq!(first, [vec![Item::ResetAll], vec![Item::Entry(rain)]]);
+}
+
+#[test]
+fn rows_switch_cycle_and_slide() {
+    let mut s = Settings::default();
+    let mut shell = shell_of(configs());
+    let (page, birds) = entry(&shell, "p:birds");
+    shell.show(page);
+    assert_eq!(
+        press(&mut shell, &mut s, birds)[0],
+        Output::Event(Event::ButtonClick)
+    );
+    assert_eq!(value(&shell, "p:birds"), Some(&ConfigValue::Bool(false)));
+    let (page, rain) = entry(&shell, "p:rain");
+    shell.show(page);
+    press(&mut shell, &mut s, rain);
+    let streaks = ConfigValue::Text("streaks".into());
+    assert_eq!(value(&shell, "p:rain"), Some(&streaks));
+    // The slider's far right end is its maximum.
+    let (page, fog) = entry(&shell, "p:fog");
+    shell.show(page);
+    let at = shell.point_at(&s, SIZE, fog);
+    let (track, width) = Columns::of(SIZE.0, SIZE.1).track();
+    shell.click(&mut s, (track + width, at.1), SIZE, false, false, false);
+    shell.release();
+    assert_eq!(value(&shell, "p:fog"), Some(&ConfigValue::Number(1.0)));
+    assert_eq!(shell.screen.configs.chosen().len(), 3);
+    // Reset all, on the first page, puts them all back, and is greyed once they are.
+    shell.show(0);
+    press(&mut shell, &mut s, Item::ResetAll);
+    assert!(shell.screen.configs.chosen().is_empty());
+    let sheets = shell.screen.sheets(&s);
+    assert!(!sheets[0].groups[0].rows[0].live);
+}
+
+#[test]
+fn the_presets_row_cycles_the_pack_wide_presets_and_shows_custom_otherwise() {
+    let mut screen = PackOptionsScreen::open(with_presets());
+    // The defaults are no preset.
+    assert_eq!(screen.current_preset(), None);
+    screen.cycle_preset(false);
+    assert_eq!(screen.current_preset().as_deref(), Some("fast"));
+    assert_eq!(screen.configs.get("p:fog"), Some(&ConfigValue::Number(0.0)));
+    screen.cycle_preset(false);
+    assert_eq!(screen.current_preset().as_deref(), Some("pretty"));
+    screen.cycle_preset(true);
+    assert_eq!(screen.current_preset().as_deref(), Some("fast"));
+    // One value off the preset: custom again.
+    screen.set("p:dust", ConfigValue::Number(0.3));
+    assert_eq!(screen.current_preset(), None);
+    let presets = &screen.sheets(&Settings::default())[0].groups[0].rows[0];
+    assert_eq!(presets.id, Item::Presets);
+    let custom = lang::get("horizon.pack.options.presets.custom");
+    assert_eq!(presets.value, Value::Choice(custom));
+}
+
+#[test]
+fn left_and_right_step_the_presets() {
+    let mut s = Settings::default();
+    let mut shell = shell_of(with_presets());
+    shell.set_focus(Some(Target::Row(Item::Presets)));
+    shell.key(&mut s, K::ArrowRight, None, false, SIZE);
+    assert_eq!(shell.screen.current_preset().as_deref(), Some("fast"));
+    shell.key(&mut s, K::ArrowRight, None, false, SIZE);
+    assert_eq!(shell.screen.current_preset().as_deref(), Some("pretty"));
+    shell.key(&mut s, K::ArrowLeft, None, false, SIZE);
+    assert_eq!(shell.screen.current_preset().as_deref(), Some("fast"));
+    assert_eq!(shell.focused_row(), Some(Item::Presets));
+}
+
+#[test]
+fn sliders_stop_at_the_entrys_step() {
+    let mut c = Configs::default();
+    let json = serde_json::json!({"default_value": 4.0, "min": 0.0, "max": 10.0, "step": 2.0});
+    c.add_entry("p:clouds".into(), &json);
+    let mut s = Settings::default();
+    let mut shell = shell_of(c);
+    let row = &shell.screen.sheets(&s)[0].groups[1].rows[0];
+    let stops = Value::Slider {
+        position: 0.4,
+        steps: Some(5),
+        text: "4".into(),
+    };
+    assert_eq!(row.value, stops);
+    // A press a little past the middle of the track lands on the step nearest it.
+    let at = shell.point_at(&s, SIZE, Item::Entry(0));
+    let (track, width) = Columns::of(SIZE.0, SIZE.1).track();
+    shell.click(
+        &mut s,
+        (track + width * 0.55, at.1),
+        SIZE,
+        false,
+        false,
+        false,
+    );
+    shell.release();
+    assert_eq!(value(&shell, "p:clouds"), Some(&ConfigValue::Number(6.0)));
+    // Held by the press, Right goes one step on and Left one back.
+    shell.set_focus(Some(Target::Row(Item::Entry(0))));
+    shell.key(&mut s, K::ArrowRight, None, false, SIZE);
+    assert_eq!(value(&shell, "p:clouds"), Some(&ConfigValue::Number(8.0)));
+    shell.key(&mut s, K::ArrowLeft, None, false, SIZE);
+    shell.key(&mut s, K::ArrowLeft, None, false, SIZE);
+    assert_eq!(value(&shell, "p:clouds"), Some(&ConfigValue::Number(4.0)));
+}
+
+/// A language with the pack's own strings: a name, a section and a tooltip.
+struct PackLang;
+impl lang::ResourceSource for PackLang {
+    fn read(&self, path: &str) -> Option<Vec<u8>> {
+        (path == "assets/minecraft/lang/en_us.json").then(|| {
+            let strings = serde_json::json!({
+                "config.minecraft.haze": "Haze",
+                "config.minecraft.haze.tooltip": "Thickens the distant air.",
+                "config.minecraft.section.sky": "Sky and fog",
+            });
+            serde_json::to_vec(&strings).unwrap()
+        })
+    }
+}
+
+fn haze() -> Configs {
+    let mut c = configs();
+    let json =
+        serde_json::json!({"default_value": false, "section": "sky", "performance_impact": "high"});
+    c.add_entry("minecraft:haze".into(), &json);
+    c
+}
+
+#[test]
+fn the_search_finds_an_entry_by_its_tooltip_and_the_strip_has_its_impact() {
+    let language = lang::Language::load(&[&PackLang], "en_us");
+    lang::scoped(language, || {
+        let s = Settings::default();
+        let mut shell = shell_of(haze());
+        let (page, haze) = entry(&shell, "minecraft:haze");
+        shell.set_search("distant air");
+        assert_eq!(shell.listed(&s, SIZE), [(page, haze)]);
+        let sheets = shell.screen.sheets(&s);
+        assert_eq!(sheets[usize::from(page)].name, "Sky and fog");
+        let row = sheets.iter().flat_map(|p| &p.groups).flat_map(|g| &g.rows);
+        let row = row.into_iter().find(|r| r.id == haze).unwrap();
+        assert_eq!(row.name, "Haze");
+        assert_eq!(
+            row.about,
+            "Thickens the distant air. Performance impact: high"
+        );
+    });
+}
+
+#[test]
+fn tab_reaches_every_row_of_every_page() {
+    let mut s = Settings::default();
+    let mut shell = shell_of(haze());
+    let pages = shell.screen.sheets(&s).len() as u16;
+    let mut seen = Vec::new();
+    for page in 0..pages {
+        shell.show(page);
+        shell.set_focus(None);
+        for _ in 0..8 {
+            shell.key(&mut s, K::Tab, None, false, SIZE);
+            if let Some(row) = shell.focused_row()
+                && !seen.contains(&row)
+            {
+                seen.push(row);
+            }
+        }
+    }
+    // Reset all is greyed at the defaults; every entry is reached.
+    let mut entries: Vec<Item> = (0..shell.screen.ids.len() as u16)
+        .map(Item::Entry)
+        .collect();
+    seen.sort_by_key(|item| format!("{item:?}"));
+    entries.sort_by_key(|item| format!("{item:?}"));
+    assert_eq!(seen, entries);
+}
+
+#[test]
+fn undo_puts_the_entries_back_and_then_leaving_sends_nothing() {
+    let mut s = Settings::default();
+    let mut shell = shell_of(configs());
+    let (page, birds) = entry(&shell, "p:birds");
+    shell.show(page);
+    press(&mut shell, &mut s, birds);
+    assert!(shell.foot_at(&s, SIZE).iter().any(|f| f.0 == Target::Undo));
+    assert!(shell.screen.finished().is_some());
+    let undo = shell
+        .foot_at(&s, SIZE)
+        .into_iter()
+        .find(|f| f.0 == Target::Undo);
+    let [x, y, w, h] = undo.unwrap().1;
+    shell.click(
+        &mut s,
+        (x + w / 2.0, y + h / 2.0),
+        SIZE,
+        false,
+        false,
+        false,
+    );
+    assert_eq!(value(&shell, "p:birds"), Some(&ConfigValue::Bool(true)));
+    assert!(!shell.foot_at(&s, SIZE).iter().any(|f| f.0 == Target::Undo));
+    assert_eq!(shell.screen.finished(), None);
+    // Stepped there and back by hand, it sends nothing either.
+    press(&mut shell, &mut s, birds);
+    press(&mut shell, &mut s, birds);
+    assert_eq!(shell.screen.finished(), None);
+    press(&mut shell, &mut s, birds);
+    let Some(Event::PackOptions { entries, chosen }) = shell.screen.finished() else {
+        panic!("a change is sent");
+    };
+    assert_eq!(entries.len(), 3);
+    assert_eq!(chosen.get("p:birds"), Some(&ConfigValue::Bool(false)));
+}

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

@@ -468,17 +468,20 @@ fn read_meta(source: &Source) -> Option<serde_json::Value> {
 /// file with a comment after the closing brace. Gson reads past a UTF-8 byte order mark;
 /// serde_json rejects it.
 pub(crate) fn parse_meta(bytes: &[u8]) -> Option<serde_json::Value> {
-    first_json(bytes)
+    first_json(bytes).ok()
 }
-
-/// Reads the first JSON value from resource metadata, matching Gson's
-/// `JsonReader` (which ignores a trailing signature or comment). Resource
-/// packs commonly append such text to texture metadata as well as pack.mcmeta.
-pub(crate) fn first_json(bytes: &[u8]) -> Option<serde_json::Value> {
-    serde_json::Deserializer::from_slice(bytes.strip_prefix(b"\xEF\xBB\xBF").unwrap_or(bytes))
+/// The first JSON value of a `.mcmeta` file, as `ResourceMetadata.fromJsonStream` reads it:
+/// Gson's `TypeAdapter.read` stops after the value, so text after it (packs leave `//` notes
+/// there) is never read, and a UTF-8 byte order mark is skipped.
+pub(crate) fn first_json<T: serde::de::DeserializeOwned>(bytes: &[u8]) -> serde_json::Result<T> {
+    let bytes = bytes.strip_prefix(b"\xEF\xBB\xBF").unwrap_or(bytes);
+    match serde_json::Deserializer::from_slice(bytes)
         .into_iter()
-        .next()?
-        .ok()
+        .next()
+    {
+        Some(value) => value,
+        None => Err(serde::de::Error::custom("empty metadata")),
+    }
 }
 /// A pack's Polytone config entries (`assets/<namespace>/polytone/config_entries/<name>.json`,
 /// in the pack's base, not its overlays) at their default values.
@@ -827,13 +830,6 @@ fn build_overlay_uncached(
     }
     // Vanilla sits below every pack, so filters hide its files too.
     let filters: Vec<&Filter> = packs.iter().flat_map(|p| &p.filter).collect();
-    let touched_dirs: BTreeSet<String> = files
-        .keys()
-        .flat_map(|f| {
-            let parts: Vec<&str> = f.split('/').collect();
-            (1..parts.len()).map(move |n| parts[..n].join("/"))
-        })
-        .collect();
     let zips: Vec<Option<Zip>> = packs
         .iter()
         .map(|p| {
@@ -882,6 +878,21 @@ fn build_overlay_uncached(
             merged.insert(name.clone(), bytes);
         }
     }
+    add_sprite_renames(
+        vanilla,
+        &merged,
+        &filters,
+        &mut files,
+        &mut hidden,
+        dependencies,
+    );
+    let touched_dirs: BTreeSet<String> = files
+        .keys()
+        .flat_map(|f| {
+            let parts: Vec<&str> = f.split('/').collect();
+            (1..parts.len()).map(move |n| parts[..n].join("/"))
+        })
+        .collect();
     /// A zip entry to write: its pack, its name in the zip and where it goes.
     type Extract<'a> = (usize, &'a str, PathBuf);
     #[allow(clippy::too_many_arguments)]
@@ -1032,6 +1043,123 @@ fn build_overlay_uncached(
     }
     extracted
 }
+/// `SingleFile` with a `sprite`: the atlas holds the resource's pixels, and the resource's
+/// `.mcmeta`, under the sprite's id. Every other sprite of the blocks and items atlases is its
+/// texture's own id, and the loaders read a model's sprite from `textures/<sprite>.png`, so the
+/// overlay gives a renamed sprite that file. ItemsAdder and Nexo packs name their models'
+/// textures only through these renames (#14485).
+///
+/// A sprite gets its resource's file only when the whole source list, in order, ends on the
+/// rename (`SpriteSourceList.list`: a later source of the same id replaces it), when the other
+/// atlas, which reads the same file, lists it from that resource too or not at all, and when it
+/// has no texture of its own. A texture that is there may be read as itself (another source's
+/// resource, an unstitched or paletted sprite's input), so no alias ever replaces one; such a
+/// sprite draws its own texture, as before aliases.
+fn add_sprite_renames(
+    vanilla: &Path,
+    merged: &BTreeMap<String, Vec<u8>>,
+    filters: &[&Filter],
+    files: &mut BTreeMap<String, (usize, Provided)>,
+    hidden: &mut BTreeSet<String>,
+    dependencies: &mut cache::Dependencies,
+) {
+    use crate::atlas_sources::{
+        SpriteOrigin, SpriteSource, decode, list, list_textures, texture_path,
+    };
+    let png = |id: &str| {
+        texture_path(Path::new(""), id, "textures")
+            .to_string_lossy()
+            .replace('\\', "/")
+    };
+    let atlases: Vec<_> = ["blocks", "items"]
+        .into_iter()
+        .filter_map(|atlas| merged.get(&format!("assets/minecraft/atlases/{atlas}.json")))
+        .filter_map(|bytes| decode(std::str::from_utf8(bytes).ok()?))
+        .collect();
+    let renamed = |source: &SpriteSource| matches!(source, SpriteSource::Single { resource, sprite: Some(sprite) } if sprite != resource);
+    if !atlases.iter().flatten().any(renamed) {
+        return;
+    }
+    // The textures a source can list: the packs' and vanilla's the packs leave visible.
+    let mut textures: Vec<String> = list_textures(vanilla)
+        .into_iter()
+        .filter(|id| {
+            let name = png(id);
+            !hidden.contains(&name) && !filters.iter().any(|f| f.blocks(&name))
+        })
+        .chain(files.keys().filter_map(|name| {
+            let (namespace, rest) = name.strip_prefix("assets/")?.split_once('/')?;
+            let path = rest.strip_prefix("textures/")?.strip_suffix(".png")?;
+            Some(format!("{namespace}:{path}"))
+        }))
+        .collect();
+    textures.sort();
+    textures.dedup();
+    // Each sprite's resource, `None` where an atlas lists it any other way.
+    let mut renames: BTreeMap<String, Option<String>> = BTreeMap::new();
+    for sources in &atlases {
+        for (sprite, origin) in list(sources, &textures) {
+            let from = match origin {
+                SpriteOrigin::File(resource) if resource != sprite => Some(resource),
+                _ => None,
+            };
+            renames
+                .entry(sprite)
+                .and_modify(|seen| {
+                    if *seen != from {
+                        *seen = None;
+                    }
+                })
+                .or_insert(from);
+        }
+    }
+    let renames = renames
+        .into_iter()
+        .filter(|(sprite, _)| textures.binary_search(sprite).is_err())
+        .filter_map(|(sprite, resource)| Some((png(&resource?), png(&sprite))));
+    // Each resource is the file the packs give, never another rename's sprite.
+    let mut found = Vec::new();
+    for (from, to) in renames {
+        // `texture_path` names an id that would leave the root as a file that is never there.
+        if !stays_inside(&from) || !stays_inside(&to) {
+            continue;
+        }
+        let from_meta = format!("{from}.mcmeta");
+        // A pack's texture with its own `.mcmeta`, or vanilla's below every pack.
+        let (file, meta) = match files.get(&from) {
+            Some(file) => (file.clone(), files.get(&from_meta).cloned()),
+            None => {
+                let (path, meta_path) = (vanilla.join(&from), vanilla.join(&from_meta));
+                dependencies.file(&path);
+                dependencies.file(&meta_path);
+                if !path.is_file() || filters.iter().any(|f| f.blocks(&from)) {
+                    continue;
+                }
+                // `createStackMetadataFinder`: a pack's filter hides vanilla's `.mcmeta` too.
+                let meta = files.get(&from_meta).cloned().or_else(|| {
+                    (meta_path.is_file() && !filters.iter().any(|f| f.blocks(&from_meta)))
+                        .then(|| (0, (Some(meta_path), from_meta.clone())))
+                });
+                ((0, (Some(path), from.clone())), meta)
+            }
+        };
+        found.push((to, file, meta));
+    }
+    for (to, file, meta) in found {
+        let to_meta = format!("{to}.mcmeta");
+        files.insert(to, file);
+        match meta {
+            Some(meta) => {
+                hidden.remove(&to_meta);
+                files.insert(to_meta, meta);
+            }
+            None => {
+                files.remove(&to_meta);
+                hidden.insert(to_meta);
+            }
+        }
+    }
+}
 /// The most the zip packs in `packs` may unpack to in one overlay: 16 times their size on disk
 /// (real packs are mostly PNGs and JSON, a few times smaller zipped at most), at least 64 MiB
 /// for a small pack of text, and never past 8 GiB.
@@ -1906,6 +2034,94 @@ mod tests {
         let _ = fs::remove_dir_all(base);
     }
     #[test]
+    fn a_renamed_atlas_sprite_reads_its_resource() {
+        let base =
+            std::env::temp_dir().join(format!("horizon-sprite-rename-{}", std::process::id()));
+        let _ = fs::remove_dir_all(&base);
+        let write = |path: PathBuf, bytes: &[u8]| {
+            fs::create_dir_all(path.parent().unwrap()).unwrap();
+            fs::write(path, bytes).unwrap();
+        };
+        let vanilla = base.join("vanilla");
+        let textures = vanilla.join("assets/minecraft/textures");
+        let animation = b"{\"animation\":{}}";
+        write(textures.join("block/sea_lantern.png"), b"lantern");
+        write(textures.join("block/sea_lantern.png.mcmeta"), animation);
+        write(textures.join("item/stick.png"), b"vanilla stick");
+        write(textures.join("item/stick.png.mcmeta"), animation);
+        let meta = br#"{"pack":{"description":"d","pack_format":97}}"#;
+        let pack = base.join("packs/IA");
+        write(pack.join("pack.mcmeta"), meta);
+        write(pack.join("assets/iageneric/textures/item/box.png"), b"box");
+        // An ItemsAdder pack's items atlas: its models name only the `ia:` sprites.
+        write(
+            pack.join("assets/minecraft/atlases/items.json"),
+            br#"{"sources":[
+                {"type":"single","resource":"iageneric:item/box","sprite":"ia:0"},
+                {"type":"single","resource":"minecraft:block/sea_lantern","sprite":"ia:1199"},
+                {"type":"single","resource":"iageneric:item/box","sprite":"minecraft:item/stick"},
+                {"type":"single","resource":"minecraft:item/stick","sprite":"ia:3"},
+                {"type":"single","resource":"iageneric:item/gone","sprite":"ia:2"},
+                {"type":"single","resource":"iageneric:item/box","sprite":"ia:../../../escape"},
+                {"type":"single","resource":"iageneric:item/box","sprite":"ia:7"},
+                {"type":"single","resource":"iageneric:item/box","sprite":"ia:8"},
+                {"type":"single","resource":"iageneric:item/box","sprite":"ia:9"}
+            ]}"#,
+        );
+        // A pack above it: later sources of three of those sprites, a blocks atlas that
+        // disagrees about another, and a filter hiding vanilla's animation of the stick.
+        let higher = base.join("packs/Top");
+        write(
+            higher.join("pack.mcmeta"),
+            br#"{"pack":{"description":"d","pack_format":97},
+                "filter":{"block":[{"path":"textures/item/stick\\.png\\.mcmeta"}]}}"#,
+        );
+        write(
+            higher.join("assets/minecraft/atlases/items.json"),
+            br#"{"sources":[
+                {"type":"single","resource":"minecraft:block/sea_lantern","sprite":"ia:8"},
+                {"type":"filter","pattern":{"namespace":"ia","path":"7"}}
+            ]}"#,
+        );
+        write(
+            higher.join("assets/minecraft/atlases/blocks.json"),
+            br#"{"sources":[
+                {"type":"single","resource":"minecraft:block/sea_lantern","sprite":"ia:9"}
+            ]}"#,
+        );
+        let packs = discover(&vanilla, &base.join("packs"));
+        let out = base.join("overlay");
+        build_overlay(&vanilla, &packs, &out).unwrap();
+        let read = |rel: &str| fs::read(out.join(rel)).ok();
+        let texture = |id: &str| read(&format!("assets/ia/textures/{id}.png"));
+        assert_eq!(texture("0").as_deref(), Some(&b"box"[..]));
+        assert_eq!(read("assets/ia/textures/0.png.mcmeta"), None);
+        // A vanilla resource comes with its animation.
+        assert_eq!(texture("1199").as_deref(), Some(&b"lantern"[..]));
+        assert_eq!(
+            read("assets/ia/textures/1199.png.mcmeta").as_deref(),
+            Some(&animation[..])
+        );
+        // A texture that is there stays itself: other sources may read it (here as `ia:3`'s
+        // resource; an unstitched or paletted sprite's input alike).
+        assert_eq!(
+            read("assets/minecraft/textures/item/stick.png").as_deref(),
+            Some(&b"vanilla stick"[..])
+        );
+        // ...with its `.mcmeta` only where no filter hides it.
+        assert_eq!(texture("3").as_deref(), Some(&b"vanilla stick"[..]));
+        assert_eq!(read("assets/ia/textures/3.png.mcmeta"), None);
+        // A missing resource adds nothing, and no rename leaves the overlay.
+        assert_eq!(texture("2"), None);
+        assert!(!out.join("escape.png").exists());
+        // The last source of a sprite wins: a filter drops it, a later rename replaces it.
+        assert_eq!(texture("7"), None);
+        assert_eq!(texture("8").as_deref(), Some(&b"lantern"[..]));
+        // The two atlases read one file, and disagree about `ia:9`: it gets neither.
+        assert_eq!(texture("9"), None);
+        let _ = fs::remove_dir_all(base);
+    }
+    #[test]
     fn every_file_of_a_big_stack_comes_from_its_top_pack() {
         use std::io::Write as _;
         let base = std::env::temp_dir().join(format!("horizon-pack-stack-{}", std::process::id()));

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

@@ -13,7 +13,8 @@ use std::{collections::BTreeSet, fs, io, path::Path, path::PathBuf};
 // Version 5 read every vanilla file to stamp it on Windows.
 // Version 6 stamps vanilla's files by their metadata on Windows too.
 // Version 7 stacks blockstate files (every pack's definition, bottom first).
-const VERSION: u32 = 8;
+// Version 8 left an atlas `single` source's renamed sprite without its texture file (#14485).
+const VERSION: u32 = 9;
 
 #[derive(Default, Serialize, Deserialize)]
 pub(super) struct Dependencies {

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

@@ -1402,100 +1402,8 @@ impl ParticleLightCache {
     }
 }
 
-const PARTICLE_SECTION_CACHE_SIZE: usize = 128;
-
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-enum SectionFrustumResult {
-    Outside,
-    Intersects,
-    Inside,
-}
-
-#[derive(Clone, Copy)]
-struct CachedSectionFrustum {
-    section: [i32; 3],
-    radius_quarters: i32,
-    result: SectionFrustumResult,
-}
-
-struct ParticleSectionFrustumCache {
-    entries: [Option<CachedSectionFrustum>; PARTICLE_SECTION_CACHE_SIZE],
-}
-
-impl Default for ParticleSectionFrustumCache {
-    fn default() -> Self {
-        Self {
-            entries: [None; PARTICLE_SECTION_CACHE_SIZE],
-        }
-    }
-}
-
-impl ParticleSectionFrustumCache {
-    fn result(
-        &mut self,
-        world: [f64; 3],
-        camera: DVec3,
-        radius: f64,
-        frustum: &crate::gfx::Frustum,
-    ) -> SectionFrustumResult {
-        let Some(section) = world_section(world) else {
-            return SectionFrustumResult::Intersects;
-        };
-        if !radius.is_finite() || radius < 0.0 || radius * 4.0 > f64::from(i32::MAX) {
-            return SectionFrustumResult::Intersects;
-        }
-        let radius_quarters = (radius * 4.0).ceil() as i32;
-        let hash = (section[0] as u32).wrapping_mul(73_856_093)
-            ^ (section[1] as u32).wrapping_mul(19_349_663)
-            ^ (section[2] as u32).wrapping_mul(83_492_791)
-            ^ (radius_quarters as u32).wrapping_mul(2_654_435_761);
-        let slot = hash as usize & (PARTICLE_SECTION_CACHE_SIZE - 1);
-        if let Some(entry) = self.entries[slot]
-            && entry.section == section
-            && entry.radius_quarters == radius_quarters
-        {
-            return entry.result;
-        }
-
-        let pad = f64::from(radius_quarters) * 0.25;
-        let camera = camera.to_array();
-        let min = array::from_fn(|axis| f64::from(section[axis]) * 16.0 - pad - camera[axis]);
-        let max = array::from_fn(|axis| min[axis] + 16.0 + 2.0 * pad);
-        let result = if min.into_iter().chain(max).any(|v| !v.is_finite()) {
-            SectionFrustumResult::Intersects
-        } else {
-            let min = FVec3::from_array(min.map(|v| v as f32));
-            let max = FVec3::from_array(max.map(|v| v as f32));
-            if !min.is_finite() || !max.is_finite() {
-                SectionFrustumResult::Intersects
-            } else if frustum.contains(min, max) {
-                SectionFrustumResult::Inside
-            } else if frustum.intersects(min, max) {
-                SectionFrustumResult::Intersects
-            } else {
-                SectionFrustumResult::Outside
-            }
-        };
-        self.entries[slot] = Some(CachedSectionFrustum {
-            section,
-            radius_quarters,
-            result,
-        });
-        result
-    }
-}
-
-fn world_section(position: [f64; 3]) -> Option<[i32; 3]> {
-    let mut block = [0; 3];
-    for axis in 0..3 {
-        let value = position[axis].floor();
-        if !value.is_finite() || value < f64::from(i32::MIN) || value > f64::from(i32::MAX) {
-            return None;
-        }
-        block[axis] = value as i32;
-    }
-    Some([block[0] >> 4, block[1] >> 4, block[2] >> 4])
-}
+mod view_cull;
+use view_cull::{PARTICLE_FRUSTUM_OFFSET, ParticleSectionFrustumCache, SectionFrustumResult};
 
 fn below_half_pixel(radius: f64, distance_squared: f64, pixel_focal_length: f32) -> bool {
     let projected_limit = 4.0 * radius * f64::from(pixel_focal_length);
@@ -4703,16 +4611,7 @@ impl ParticleEngine {
         light_at: &dyn Fn([i32; 3]) -> u8,
         out: &mut Vec<Vertex>,
     ) {
-        self.render_inner::<false>(
-            camera,
-            base,
-            partial,
-            0.0,
-            None,
-            &mut |_, _| false,
-            light_at,
-            out,
-        );
+        self.render_in_view(camera, base, partial, None, light_at, out);
     }
 
     /// Render particles after rejecting view-frustum misses and any particles
@@ -4730,7 +4629,7 @@ impl ParticleEngine {
         out: &mut Vec<Vertex>,
     ) {
         if !culling_enabled {
-            self.render(camera, base, partial, light_at, out);
+            self.render_in_view(camera, base, partial, frustum, light_at, out);
             return;
         }
         self.render_inner::<true>(
@@ -4761,10 +4660,16 @@ impl ParticleEngine {
         additive.clear();
         let mut section_cache =
             (CULL && frustum.is_some()).then(ParticleSectionFrustumCache::default);
+        let view = frustum.map(|f| f.pulled_back(PARTICLE_FRUSTUM_OFFSET));
         for p in &self.particles {
             if p.no_render {
                 continue;
             }
+            if let Some(view) = &view
+                && !view_cull::in_view(view, p, camera)
+            {
+                continue;
+            }
             // SparkParticle.extract: twinkling sparks blink after a third of their life.
             if let Behaviour::Spark { twinkle: true, .. } = p.behaviour
                 && p.age >= p.lifetime / 3
@@ -5199,6 +5104,115 @@ mod tests {
         assert_eq!(attributes(&disabled), attributes(&regular));
     }
 
+    /// An engine whose smoke particles stand at `positions`, camera-relative (the camera is at
+    /// the origin looking down -z, like `Mat4::IDENTITY` as a view).
+    fn smoke_at(positions: &[[f64; 3]]) -> ParticleEngine {
+        let mut engine = ParticleEngine::new(Path::new(""), &HashMap::new(), &HashSet::new());
+        let sprite = "test:smoke".to_owned();
+        engine.atlas.insert(
+            sprite.clone(),
+            (
+                Rect {
+                    u0: 0.0,
+                    v0: 0.0,
+                    u1: 1.0,
+                    v1: 1.0,
+                    w: 16,
+                    h: 16,
+                },
+                false,
+            ),
+        );
+        let mut random = LegacyRandom::new(7);
+        for &at in positions {
+            let mut particle = Particle::moving(&mut random, ParticleType::Smoke, at, [0.0; 3]);
+            particle.sprite = Sprite::Named(sprite.clone());
+            engine.particles.push(particle);
+        }
+        engine
+    }
+
+    fn quad_vertices(engine: &ParticleEngine, view: Option<&crate::gfx::Frustum>) -> usize {
+        let mut out = Vec::new();
+        engine.render_in_view(DVec3::ZERO, Quat::IDENTITY, 0.5, view, &|_| 0xf0, &mut out);
+        out.len()
+    }
+
+    #[test]
+    fn particles_outside_the_pulled_back_frustum_make_no_quads() {
+        use crate::gfx::{Frustum, world_projection};
+        let view = Frustum::from_view_projection(world_projection(70.0, 16.0 / 9.0, 512.0));
+        let kept = [
+            [0.0, 0.0, -5.0],   // straight ahead
+            [0.0, 0.0, 2.5],    // behind the camera, inside the 3 blocks of offset
+            [0.0, 0.0, -300.0], // far, inside the far plane
+        ];
+        let dropped = [
+            [0.0, 0.0, 10.0],   // well behind the camera
+            [0.0, 0.0, 3.5],    // just past the offset
+            [100.0, 0.0, -5.0], // far to the side
+            [0.0, 60.0, -5.0],  // far above
+            [0.0, 0.0, -600.0], // beyond the far plane
+        ];
+        let all: Vec<_> = kept.iter().chain(&dropped).copied().collect();
+        let engine = smoke_at(&all);
+        let only_kept = quad_vertices(&smoke_at(&kept), None);
+        assert!(only_kept > 0);
+        assert_eq!(quad_vertices(&engine, Some(&view)), only_kept);
+        // Without a view every particle is drawn, as before.
+        assert_eq!(
+            quad_vertices(&engine, None),
+            only_kept * all.len() / kept.len()
+        );
+        // `render` is the same as no view.
+        let mut regular = Vec::new();
+        engine.render(DVec3::ZERO, Quat::IDENTITY, 0.5, &|_| 0xf0, &mut regular);
+        assert_eq!(regular.len(), quad_vertices(&engine, None));
+    }
+
+    #[test]
+    fn the_culled_path_applies_the_same_frustum_test() {
+        use crate::gfx::{Frustum, world_projection};
+        let view = Frustum::from_view_projection(world_projection(70.0, 16.0 / 9.0, 512.0));
+        let engine = smoke_at(&[[0.0, 0.0, -5.0], [0.0, 0.0, 10.0]]);
+        let mut out = Vec::new();
+        // The disabled setting still keeps vanilla's always-on test.
+        engine.render_culled(
+            DVec3::ZERO,
+            Quat::IDENTITY,
+            0.5,
+            900.0,
+            false,
+            Some(&view),
+            |_, _| panic!("disabled culling must not query particle visibility"),
+            &|_| 0xf0,
+            &mut out,
+        );
+        assert_eq!(
+            out.len(),
+            quad_vertices(&smoke_at(&[[0.0, 0.0, -5.0]]), None)
+        );
+    }
+
+    #[test]
+    fn a_particle_is_tested_at_its_position_this_tick_not_an_interpolated_one() {
+        use crate::gfx::{Frustum, world_projection};
+        let view = Frustum::from_view_projection(world_projection(70.0, 16.0 / 9.0, 512.0));
+        // The frame is drawn half way (0.5) between `previous` and `position`.
+        // Ahead now, far behind a tick ago (half way: 12.5 behind, outside): kept.
+        let mut coming = smoke_at(&[[0.0, 0.0, -5.0]]);
+        coming.particles[0].previous = [0.0, 0.0, 30.0];
+        assert!(quad_vertices(&coming, None) > 0);
+        assert_eq!(
+            quad_vertices(&coming, Some(&view)),
+            quad_vertices(&coming, None)
+        );
+        // Behind now, ahead a tick ago (half way: 5 ahead, inside): dropped.
+        let mut going = smoke_at(&[[0.0, 0.0, 10.0]]);
+        going.particles[0].previous = [0.0, 0.0, -20.0];
+        assert_eq!(quad_vertices(&going, Some(&view)), 0);
+    }
+
     #[test]
     fn quads_face_the_rotation_they_are_given() {
         let mut engine = ParticleEngine::new(Path::new(""), &HashMap::new(), &HashSet::new());

crates/horizon-client-render/src/particles/view_cull.rs

@@ -0,0 +1,138 @@
+//! The camera's view frustum for particles: vanilla's always-on point test, and the section
+//! cache behind the opt-in Particle Culling setting.
+
+use super::{Particle, ParticleEngine, Vertex};
+use glam::{DVec3, Quat, Vec3 as FVec3};
+use std::array;
+
+const PARTICLE_SECTION_CACHE_SIZE: usize = 128;
+/// How far back, in blocks, the camera's frustum is pulled for the particle test (vanilla's
+/// `Frustum.offset` in `ParticleEngine.extract`).
+pub(super) const PARTICLE_FRUSTUM_OFFSET: f32 = 3.0;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(super) enum SectionFrustumResult {
+    Outside,
+    Intersects,
+    Inside,
+}
+
+#[derive(Clone, Copy)]
+struct CachedSectionFrustum {
+    section: [i32; 3],
+    radius_quarters: i32,
+    result: SectionFrustumResult,
+}
+
+pub(super) struct ParticleSectionFrustumCache {
+    entries: [Option<CachedSectionFrustum>; PARTICLE_SECTION_CACHE_SIZE],
+}
+
+impl Default for ParticleSectionFrustumCache {
+    fn default() -> Self {
+        Self {
+            entries: [None; PARTICLE_SECTION_CACHE_SIZE],
+        }
+    }
+}
+
+impl ParticleSectionFrustumCache {
+    pub(super) fn result(
+        &mut self,
+        world: [f64; 3],
+        camera: DVec3,
+        radius: f64,
+        frustum: &crate::gfx::Frustum,
+    ) -> SectionFrustumResult {
+        let Some(section) = world_section(world) else {
+            return SectionFrustumResult::Intersects;
+        };
+        if !radius.is_finite() || radius < 0.0 || radius * 4.0 > f64::from(i32::MAX) {
+            return SectionFrustumResult::Intersects;
+        }
+        let radius_quarters = (radius * 4.0).ceil() as i32;
+        let hash = (section[0] as u32).wrapping_mul(73_856_093)
+            ^ (section[1] as u32).wrapping_mul(19_349_663)
+            ^ (section[2] as u32).wrapping_mul(83_492_791)
+            ^ (radius_quarters as u32).wrapping_mul(2_654_435_761);
+        let slot = hash as usize & (PARTICLE_SECTION_CACHE_SIZE - 1);
+        if let Some(entry) = self.entries[slot]
+            && entry.section == section
+            && entry.radius_quarters == radius_quarters
+        {
+            return entry.result;
+        }
+
+        let pad = f64::from(radius_quarters) * 0.25;
+        let camera = camera.to_array();
+        let min = array::from_fn(|axis| f64::from(section[axis]) * 16.0 - pad - camera[axis]);
+        let max = array::from_fn(|axis| min[axis] + 16.0 + 2.0 * pad);
+        let result = if min.into_iter().chain(max).any(|v| !v.is_finite()) {
+            SectionFrustumResult::Intersects
+        } else {
+            let min = FVec3::from_array(min.map(|v| v as f32));
+            let max = FVec3::from_array(max.map(|v| v as f32));
+            if !min.is_finite() || !max.is_finite() {
+                SectionFrustumResult::Intersects
+            } else if frustum.contains(min, max) {
+                SectionFrustumResult::Inside
+            } else if frustum.intersects(min, max) {
+                SectionFrustumResult::Intersects
+            } else {
+                SectionFrustumResult::Outside
+            }
+        };
+        self.entries[slot] = Some(CachedSectionFrustum {
+            section,
+            radius_quarters,
+            result,
+        });
+        result
+    }
+}
+
+fn world_section(position: [f64; 3]) -> Option<[i32; 3]> {
+    let mut block = [0; 3];
+    for axis in 0..3 {
+        let value = position[axis].floor();
+        if !value.is_finite() || value < f64::from(i32::MIN) || value > f64::from(i32::MAX) {
+            return None;
+        }
+        block[axis] = value as i32;
+    }
+    Some([block[0] >> 4, block[1] >> 4, block[2] >> 4])
+}
+
+/// Whether `QuadParticleGroup`'s test keeps `particle`: its position this tick (camera-relative, not
+/// interpolated) is on or inside `view`, the camera's frustum pulled back [`PARTICLE_FRUSTUM_OFFSET`] blocks.
+pub(super) fn in_view(view: &crate::gfx::Frustum, particle: &Particle, camera: DVec3) -> bool {
+    let at = DVec3::from_array(particle.position) - camera;
+    view.contains_point(at.as_vec3())
+}
+
+impl ParticleEngine {
+    /// [`Self::render`], keeping only the particles inside `view`, the camera's frustum pulled
+    /// back [`PARTICLE_FRUSTUM_OFFSET`] blocks (vanilla's `ParticleEngine.extract` and
+    /// `QuadParticleGroup`): the test runs whatever the Particle Culling setting says. With
+    /// `None`, every particle is drawn.
+    pub fn render_in_view(
+        &self,
+        camera: DVec3,
+        base: Quat,
+        partial: f32,
+        view: Option<&crate::gfx::Frustum>,
+        light_at: &dyn Fn([i32; 3]) -> u8,
+        out: &mut Vec<Vertex>,
+    ) {
+        self.render_inner::<false>(
+            camera,
+            base,
+            partial,
+            0.0,
+            view,
+            &mut |_, _| false,
+            light_at,
+            out,
+        );
+    }
+}

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

@@ -222,11 +222,6 @@ impl<P: Copy, S: Copy> Lines<P, S> {
         }
         self.y += style::GROUP_GAP;
     }
-    /// A group of rows under its page's own name (`list`'s `page_name`), for pages named at run
-    /// time, such as a resource pack's config entries (`pack_options_ui`).
-    pub(crate) fn titled(&mut self, page: P, rows: Vec<S>) {
-        self.group(page, "", rows);
-    }
     /// The lines and the content's height.
     pub(crate) fn finish(self) -> (Vec<Line<P, S>>, f32) {
         (self.lines, (self.y - style::GROUP_GAP).max(0.0))
@@ -352,8 +347,7 @@ pub(crate) fn plate(batch: &mut HudBatch, atlas: &HudAtlas, cols: &Columns, head
 }
 
 /// The list, clipped to its view: each group's panel, then its names and rows on it. `row`
-/// draws a setting at its `y`; `page_name` names a page, and a group without a name of its own
-/// (`Lines::titled`), in the player's language.
+/// draws a setting at its `y`; `page_name` names a page, in the player's language.
 pub(crate) fn list<P: Copy, S: Copy>(
     batch: &mut HudBatch,
     atlas: &HudAtlas,
@@ -386,7 +380,6 @@ pub(crate) fn list<P: Copy, S: Copy>(
         }
         let Some(setting) = line.setting else {
             let (name, color, dy) = match line.group {
-                Some(("", _)) => (page_name(line.page), style::muted(), 3.0),
                 Some((name, _)) => (lang::get(name), style::muted(), 3.0),
                 None => (page_name(line.page), style::accent(), 4.0),
             };
@@ -952,22 +945,10 @@ pub(crate) fn dock_note(
     }
 }
 
-/// Done or Undo at the foot of the page list.
+/// Done, Undo or Apply at the foot of the page list, registered for a controller. Its label
+/// leaves `room` at its left for a controller's glyph: a button that declared its job gets one,
+/// as vanilla's do (`ui::action_button`), which a half-width Undo or Apply needs.
 pub(crate) fn foot_button(
-    batch: &mut HudBatch,
-    atlas: &HudAtlas,
-    rect: [f32; 4],
-    label: &Text,
-    cursor: (f32, f32),
-    flags: (bool, bool),
-) {
-    foot_button_with_room(batch, atlas, rect, label, cursor, flags, 0.0);
-}
-
-/// A foot button whose label leaves `room` at its left for a controller's glyph: a button that
-/// declared its job gets one, as vanilla's do (`ui::action_button`), which a half-width Undo or
-/// Apply needs.
-fn foot_button_with_room(
     batch: &mut HudBatch,
     atlas: &HudAtlas,
     rect: [f32; 4],
@@ -2414,7 +2395,7 @@ impl<S: Screen + Default> Hosted for Shell<S> {
                 }
                 None => 0.0,
             };
-            foot_button_with_room(batch, atlas, rect, &label, cursor, flags, room);
+            foot_button(batch, atlas, rect, &label, cursor, flags, room);
         }
     }
     fn click(

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

@@ -478,9 +478,9 @@ impl Sprites {
         let metadata = match horizon_core::prepared_files::read_to_string(
             &path.with_extension("png.mcmeta"),
         ) {
-            Ok(text) => Some(serde_json::from_str::<
+            Ok(text) => Some(crate::packs::first_json::<
                 BTreeMap<String, Box<serde_json::value::RawValue>>,
-            >(&text)?),
+            >(text.as_bytes())?),
             Err(error) if error.kind() == std::io::ErrorKind::NotFound => None,
             Err(error) => return Err(error.into()),
         };
@@ -589,9 +589,9 @@ impl Sprites {
         let metadata = match horizon_core::prepared_files::read_to_string(
             &path.with_extension("png.mcmeta"),
         ) {
-            Ok(text) => Some(serde_json::from_str::<
+            Ok(text) => Some(crate::packs::first_json::<
                 BTreeMap<String, Box<serde_json::value::RawValue>>,
-            >(&text)?),
+            >(text.as_bytes())?),
             Err(error) if error.kind() == std::io::ErrorKind::NotFound => None,
             Err(error) => return Err(error.into()),
         };

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

@@ -1438,7 +1438,7 @@ impl Streaming {
         let entities = std::mem::take(&mut chunk.entities);
         world.entities_pending.insert((chunk.x, chunk.z));
         if !entities.is_empty() {
-            world.loaded_entities.push(((chunk.x, chunk.z), entities));
+            world.queue_entity_nbt((chunk.x, chunk.z), entities);
         }
         self.generated_total += 1;
         // A chunk saved with its light needs no light job; its unlit

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

@@ -104,7 +104,7 @@ pub fn read_metadata(root: &Path) -> UiMetadata {
         let Ok(text) = horizon_core::prepared_files::read_to_string(&p) else {
             continue;
         };
-        let Some(nine_slice) = serde_json::from_str(&text)
+        let Some(nine_slice) = crate::packs::first_json(text.as_bytes())
             .ok()
             .as_ref()
             .and_then(parse_nine_slice)
@@ -2025,6 +2025,28 @@ impl EditBox {
 mod tests {
     use super::*;
 
+    #[test]
+    fn notes_after_a_sprites_metadata_keep_its_nine_slice() {
+        // Gson stops reading after the first value, so vanilla keeps this nine slice
+        // (CozyUI+'s highlighted button, #3046).
+        let root = std::env::temp_dir().join(format!("horizon-ui-meta-{}", std::process::id()));
+        let widget = root.join("assets/minecraft/textures/gui/sprites/widget");
+        std::fs::create_dir_all(&widget).unwrap();
+        std::fs::write(
+            widget.join("button_highlighted.png.mcmeta"),
+            "{\"gui\": {\"scaling\": {\"type\": \"nine_slice\", \"width\": 80, \"height\": 20,\n\
+             \"border\": {\"left\": 34, \"top\": 8, \"right\": 34, \"bottom\": 8}}}}\n\n// 0  10\n// 1  8\n",
+        )
+        .unwrap();
+        let metadata = read_metadata(&root);
+        std::fs::remove_dir_all(&root).unwrap();
+        let slice = metadata.0["gui/sprites/widget/button_highlighted"];
+        assert_eq!(
+            (slice.width, slice.height, slice.border),
+            (80, 20, [34, 8, 34, 8])
+        );
+    }
+
     /// The quads' destination rectangles and their UVs.
     fn quads(batch: &HudBatch) -> Vec<([f32; 4], [f32; 4])> {
         batch

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

@@ -9,6 +9,9 @@ use horizon_core::random::{LegacyRandom, LevelRandom};
 use horizon_world::registry::BlockStateId;
 use std::sync::Arc;
 
+mod pending_entity;
+pub use pending_entity::{EntityLoadReason, PendingEntity};
+
 mod modified;
 pub use modified::ModifiedChunks;
 
@@ -81,7 +84,7 @@ pub struct World {
     /// incrementally by streaming.
     pub light_edits: Vec<((i32, i32, i32), u32, u32)>,
     /// Saved entities of chunks that just loaded, spawned by the game.
-    pub loaded_entities: Vec<((i32, i32), Vec<horizon_world::nbt::Tag>)>,
+    pub loaded_entities: Vec<((i32, i32), Vec<PendingEntity>)>,
     /// Chunks loaded since the level's last pass, their entity sections not
     /// ready yet (`PersistentEntitySectionManager`'s PENDING), empty ones too:
     /// the pass ends by readying them (`processPendingLoads`).
@@ -215,6 +218,12 @@ impl Weather {
     }
 }
 impl World {
+    /// Queue ordinary NBT; transient transfer state is never decoded from it.
+    pub fn queue_entity_nbt(&mut self, key: (i32, i32), tags: Vec<horizon_world::nbt::Tag>) {
+        self.loaded_entities
+            .push((key, tags.into_iter().map(PendingEntity::from).collect()));
+    }
+
     pub fn new(air: BlockStateId, seed: i64) -> Self {
         Self {
             shape: LevelShape::OVERWORLD,

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

@@ -0,0 +1,89 @@
+//! Pending entity NBT and the runtime context that must not be stored inside it.
+use horizon_world::nbt::Tag;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum EntityLoadReason {
+    Ordinary,
+    TeleportedTnt,
+}
+
+#[derive(Clone, Debug)]
+pub struct PendingEntity {
+    tag: Tag,
+    reason: EntityLoadReason,
+}
+
+impl From<Tag> for PendingEntity {
+    fn from(tag: Tag) -> Self {
+        Self {
+            tag,
+            reason: EntityLoadReason::Ordinary,
+        }
+    }
+}
+
+impl PendingEntity {
+    /// Only an in-memory TNT transfer supplies this context, never saved NBT.
+    pub fn after_tnt_portal(tag: Tag) -> Self {
+        Self {
+            tag,
+            reason: EntityLoadReason::TeleportedTnt,
+        }
+    }
+
+    pub fn into_parts(self) -> (Tag, EntityLoadReason) {
+        (self.tag, self.reason)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn ordinary_nbt_cannot_request_transient_portal_state() {
+        for marker in [0, 1] {
+            let tag = Tag::compound([("horizon:tnt_used_portal", Tag::Byte(marker))]);
+            let (loaded, reason) = PendingEntity::from(tag.clone()).into_parts();
+            assert_eq!(loaded, tag);
+            assert_eq!(reason, EntityLoadReason::Ordinary);
+        }
+    }
+
+    #[test]
+    fn queue_swaps_and_appends_keep_each_entitys_context_and_order() {
+        let ordinary = Tag::compound([("id", Tag::String("ordinary".into()))]);
+        let transfer = Tag::compound([("id", Tag::String("transfer".into()))]);
+        let mut batches = vec![(
+            (1, 2),
+            vec![
+                ordinary.clone().into(),
+                PendingEntity::after_tnt_portal(transfer.clone()),
+            ],
+        )];
+        let mut waiting = std::mem::take(&mut batches);
+        batches.push(((3, 4), vec![ordinary.clone().into()]));
+        waiting.append(&mut batches);
+        assert!(batches.is_empty());
+        let mut batches = waiting.into_iter();
+        let (key, entities) = batches.next().unwrap();
+        assert_eq!(key, (1, 2));
+        let mut entities = entities.into_iter();
+        assert_eq!(
+            entities.next().unwrap().into_parts(),
+            (ordinary.clone(), EntityLoadReason::Ordinary)
+        );
+        assert_eq!(
+            entities.next().unwrap().into_parts(),
+            (transfer, EntityLoadReason::TeleportedTnt)
+        );
+        assert!(entities.next().is_none());
+        let (key, entities) = batches.next().unwrap();
+        assert_eq!(key, (3, 4));
+        assert_eq!(
+            entities.into_iter().next().unwrap().into_parts(),
+            (ordinary, EntityLoadReason::Ordinary)
+        );
+        assert!(batches.next().is_none());
+    }
+}

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

@@ -316,6 +316,7 @@
   "horizon.multiplayer.invite_code": "Invite Code",
   "horizon.multiplayer.relay": "Relay (optional)",
   "Preset": "Preset",
+  "Horizon Preset": "Horizon Preset",
   "LOD Distance": "LOD Distance",
   "Far Detail": "Far Detail",
   "Cave Culling": "Cave Culling",
@@ -707,6 +708,9 @@
   "Pick a shader pack. Picking the one in use turns shaders off.": "Pick a shader pack. Picking the one in use turns shaders off.",
   "Changed options apply with Apply, or when you leave.": "Changed options apply with Apply, or when you leave.",
   "Pack settings": "Pack settings",
+  "Whole pack": "Whole pack",
+  "Reset all": "Reset all",
+  "Every option is at its default already.": "Every option is at its default already.",
   "Built-in settings": "Built-in settings",
   "%s settings": "%s settings",
   "Settings made by the pack's author: they change only this pack.": "Settings made by the pack's author: they change only this pack.",

crates/horizon-client/build.rs

@@ -21,5 +21,19 @@ fn main() {
     if !staged.is_empty() {
         println!("cargo:rustc-env=HORIZON_MIXIN_MODS={}", staged.join(","));
     }
+    // Whether a native mod can run in a mob's turn (`game/creatures/mob_islands.rs`). The
+    // launcher adds trait packages to the workspace's members.
+    println!(
+        "cargo:rerun-if-changed={}",
+        root.join("Cargo.toml").display()
+    );
+    for dir in ["native-api", "native-crates"] {
+        if root.join(dir).is_dir() {
+            println!("cargo:rerun-if-changed={}", root.join(dir).display());
+        }
+    }
+    if let Some(found) = horizon_mod_api_gen::mob_turn(&root) {
+        println!("cargo:rustc-env=HORIZON_MOB_TURN={found}");
+    }
     windows_exe::resources("horizon-client");
 }

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

@@ -318,6 +318,8 @@ pub fn main() -> horizon_client::Result<()> {
                         Ok(())
                     }
                     drops::Drop::Orb(v) => writeln!(out, "orb {v}"),
+                    // The star's `setExtendedLifetime` is no part of the loot.
+                    drops::Drop::Aged(s, _) => writeln!(out, "{}", line(&s)),
                 };
             }
         }

crates/horizon-client/src/advancements.rs

@@ -1517,10 +1517,8 @@ fn predicate_references(
                 .unwrap_or("");
             match &*full(kind) {
                 "minecraft:inverted" => predicate_references(&v["term"], w, active),
-                "minecraft:all_of" | "minecraft:any_of" => v["terms"]
-                    .as_array()
-                    .into_iter()
-                    .flatten()
+                "minecraft:all_of" | "minecraft:any_of" => terms(v)
+                    .iter()
                     .try_for_each(|v| predicate_references(v, w, active)),
                 _ => Ok(()),
             }
@@ -1529,6 +1527,16 @@ fn predicate_references(
     }
 }
 
+/// `terms` as `HolderSetCodec` reads it: a list, or one holder alone; a `#tag` is not expanded.
+fn terms(v: &Value) -> &[Value] {
+    match &v["terms"] {
+        Value::Array(list) => list,
+        Value::Null => &[],
+        Value::String(tag) if tag.starts_with('#') => &[],
+        one => std::slice::from_ref(one),
+    }
+}
+
 /// The existing condition traversal with a caller-owned leaf context.
 /// Leaves run synchronously, in order, with normal boolean short-circuiting.
 pub fn conditions_with(
@@ -1547,16 +1555,8 @@ pub fn conditions_with(
                 .unwrap_or("");
             match &*full(ty) {
                 "minecraft:inverted" => !conditions_with(&v["term"], ctx, test),
-                "minecraft:all_of" => v["terms"]
-                    .as_array()
-                    .into_iter()
-                    .flatten()
-                    .all(|t| conditions_with(t, ctx, test)),
-                "minecraft:any_of" => v["terms"]
-                    .as_array()
-                    .into_iter()
-                    .flatten()
-                    .any(|t| conditions_with(t, ctx, test)),
+                "minecraft:all_of" => terms(v).iter().all(|t| conditions_with(t, ctx, test)),
+                "minecraft:any_of" => terms(v).iter().any(|t| conditions_with(t, ctx, test)),
                 _ => test(v, ctx),
             }
         }

crates/horizon-client/src/block_contact.rs

@@ -71,6 +71,10 @@ pub fn trample_allowed(entity: i32, kind: &str, position: BlockPos, distance: f6
     let (Some(dimension), Some(hook)) = (LEVEL.get(), TRAMPLE.get()) else {
         return true;
     };
+    // A grouped mob turn: no mod hooks it (`native_client_hooks::Deferred`).
+    if crate::native_client_hooks::deferring() {
+        return true;
+    }
     let mut cancel = false;
     let at = [position.x, position.y, position.z];
     hook(dimension, entity, kind, at, distance, &mut cancel);
@@ -87,7 +91,8 @@ fn dispatch(event: Event<'_>, damage: &mut f32) {
     let contact = match event {
         Event::StepOn(c) | Event::Inside(c) | Event::FallOn(c, _) => c,
     };
-    if contact.block.starts_with("minecraft:") {
+    // A grouped mob turn reaches no mod's hook (`native_client_hooks::Deferred`).
+    if contact.block.starts_with("minecraft:") || crate::native_client_hooks::deferring() {
         return;
     }
     if let Some(dimension) = LEVEL.get()
@@ -213,6 +218,15 @@ mod tests {
             let bounds = bounds.move_by(Vec3::new(-1.0, 0.0, 0.0));
             swept_inside(17, c.kind, at, at, bounds, block);
             assert_eq!(SEEN.get(), 8, "stationary overlap still notifies");
+            // A grouped mob turn, on any thread: no mod hears its contacts or tramples.
+            let ((), _) = crate::native_client_hooks::deferring_turn(|| {
+                emit(Event::StepOn(c));
+                assert_eq!(fall(c, 12.0, 10.0), 10.0);
+                let _ = TRAMPLE.set(|_, _, _, _, _, cancel| *cancel = true);
+                assert!(trample_allowed(17, c.kind, c.position, 12.0));
+            });
+            assert_eq!(SEEN.get(), 8, "a grouped turn reaches no contact hook");
+            assert!(!trample_allowed(17, c.kind, c.position, 12.0));
         });
         let _ =
             std::panic::catch_unwind(|| in_level(Some("minecraft:the_nether"), || panic!("test")));

crates/horizon-client/src/block_entity_item.rs

@@ -123,18 +123,32 @@ pub fn spawn_egg_entity_data<'a>(
 
 /// `EntityType.appendDefaultStackConfig` for a hanging entity or armor stand an
 /// item places: `Entity.applyImplicitComponents` stores the item's
-/// `minecraft:custom_data` as the entity's `data`, then `updateCustomEntityTag`
+/// `minecraft:custom_name` as the entity's `CustomName` and its
+/// `minecraft:custom_data` as its `data`, then `updateCustomEntityTag`
 /// (`TypedEntityData.loadInto`) merges the item's `minecraft:entity_data` over
 /// the entity's saved tag `own` when its type is `kind`.
 pub fn stack_configured_entity(stack: &crate::items::ItemStack, kind: &str, own: &Tag) -> Tag {
+    stack_configured_entity_by(stack, kind, own, false)
+}
+
+/// [`stack_configured_entity`], `op` saying whether the user may load the
+/// data of an op-only entity type (`EntityType.onlyOpCanSetNbt`).
+pub fn stack_configured_entity_by(
+    stack: &crate::items::ItemStack,
+    kind: &str,
+    own: &Tag,
+    op: bool,
+) -> Tag {
     let mut tag = own.clone();
-    if let (Tag::Compound(map), Some(custom)) = (
-        &mut tag,
-        stack.data().and_then(|d| d.other("minecraft:custom_data")),
-    ) {
-        map.insert("data".into(), custom.clone());
+    if let Tag::Compound(map) = &mut tag {
+        if let Some(name) = stack.data().and_then(|d| d.custom_name.clone()) {
+            map.insert("CustomName".into(), name);
+        }
+        if let Some(custom) = stack.data().and_then(|d| d.other("minecraft:custom_data")) {
+            map.insert("data".into(), custom.clone());
+        }
     }
-    match spawn_egg_entity_data(stack, kind, false) {
+    match spawn_egg_entity_data(stack, kind, op) {
         Some(data) => crate::data_cmd::merged(&tag, data),
         None => tag,
     }

crates/horizon-client/src/debugworld.rs

@@ -75,6 +75,12 @@ fn grid_state(count: u32, mut x: i32, mut z: i32) -> u32 {
 impl ChunkGenerator for DebugTerrain {
     type Worker = ();
     fn worker(&self) {}
+    /// DebugLevelSource's proto is already its decorated column. Keep a copy
+    /// for lighting a finished neighbour outside the kept area, matching the
+    /// vanilla FEATURES neighbour path.
+    fn light_view(&self, proto: &crate::streaming::Proto) -> Option<Chunk> {
+        proto.downcast_ref::<Chunk>().cloned()
+    }
     /// `DebugLevelSource.buildTerrain` builds nothing; `applyBiomeDecoration`
     /// writes the barriers and the grid.
     fn proto(&self, _: &mut (), cx: i32, cz: i32) -> crate::streaming::Proto {
@@ -128,4 +134,20 @@ mod tests {
         assert_eq!(grid_state(1000, 65, 1), 0);
         assert_eq!(grid_state(1000, 61, 3), 30 * 32 + 1);
     }
+
+    #[test]
+    fn light_view_keeps_a_debug_proto_column() {
+        let terrain = DebugTerrain {
+            shape: LevelShape::OVERWORLD,
+            biome: 0,
+            barrier: 0,
+            states: 0,
+        };
+        let mut chunk = Chunk::empty(-2, 5);
+        chunk.set(0, 0, 0, 42);
+        let proto: crate::streaming::Proto = Box::new(chunk);
+        let view = terrain.light_view(&proto).expect("debug proto light view");
+        assert_eq!((view.x, view.z), (-2, 5));
+        assert_eq!(view.block(0, 0, 0).0, 42);
+    }
 }

crates/horizon-client/src/entity_nbt.rs

@@ -1652,9 +1652,7 @@ pub fn mob_to_nbt(
         if let Some(saddle) = m.saddle_item() {
             equipment.insert("saddle".into(), crate::save::item_to_nbt(&saddle));
         }
-        // A happy ghast wears its harness in the body slot (and a nautilus
-        // its armour, a sulfur cube its swallowed block, a wolf its armor,
-        // with the durability it lost).
+        // Body slot: harness, armour, a cube's block, a wolf's armor; emptied, it leaves the earlier save.
         if crate::mobs::species::body_slot(m.species())
             && let Some(id) = &m.extra.body
         {
@@ -1664,6 +1662,8 @@ pub fn mob_to_nbt(
                 stack.extra = m.extra.body_extra.clone();
             }
             equipment.insert("body".into(), crate::save::item_to_nbt(&stack));
+        } else if crate::mobs::species::body_slot(m.species()) {
+            equipment.remove(&"body".into());
         }
         // Vanilla saves `equipment` only when something is equipped.
         if equipment.is_empty() {
@@ -2867,7 +2867,7 @@ pub fn evoker_fangs_to_nbt(
         motion: raw.map(motion).unwrap_or(Vec3::ZERO),
         rotation: [yaw, raw.map(rotation).unwrap_or([0.0; 2])[1]],
         on_ground: raw.is_some_and(|t| flag(t, "OnGround")),
-        fall_distance: 0.0,
+        fall_distance: raw.map_or(0.0, |t| ground_from_nbt(t).1),
     }
     .tag(raw);
     put(&mut tag, "Warmup", Tag::Int(warmup));
@@ -4163,6 +4163,28 @@ mod tests {
         );
     }
 
+    /// `EvokerFangs` extends `Entity` and never moves: `Entity.saveWithoutId`
+    /// writes the `fall_distance` it loaded, and 0 for fangs a spell made.
+    #[test]
+    fn evoker_fangs_keep_their_loaded_fall_distance() {
+        let raw = horizon_world::nbt::parse_snbt(
+            "{id:\"minecraft:evoker_fangs\",Pos:[1d,200d,1d],fall_distance:5.0d,Warmup:100}",
+        )
+        .unwrap()
+        .0;
+        let at = super::Vec3::new(1.0, 200.0, 1.0);
+        let fall = |raw: Option<&super::Tag>| match super::evoker_fangs_to_nbt(
+            at, 0.0, 99, None, [1; 4], raw,
+        )
+        .get("fall_distance")
+        {
+            Some(super::Tag::Double(bits)) => f64::from_bits(*bits),
+            other => panic!("no fall_distance: {other:?}"),
+        };
+        assert_eq!(fall(Some(&raw)), 5.0);
+        assert_eq!(fall(None), 0.0);
+    }
+
     /// `Shulker` reads `AttachFace` as a byte before
     /// `Direction.from3DDataValue` (`abs(data % 6)`): an int is narrowed
     /// first, so 258 is byte 2, not 258 % 6 = 0, and 250 is byte -6, face 0.
@@ -4549,6 +4571,37 @@ mod tests {
         assert_eq!(id("head"), "minecraft:iron_helmet");
     }
 
+    /// A body item taken off (`/item replace entity <cube> armor.body with minecraft:air`)
+    /// is not saved again from the entity's earlier save: vanilla writes `equipment.body` only
+    /// while the slot holds something (#12038).
+    #[test]
+    fn an_emptied_body_slot_is_not_saved_from_the_earlier_nbt() {
+        let mut kind = crate::mobs::sensor_scan_tests::kind();
+        let ty = Arc::make_mut(&mut kind);
+        ty.id = "minecraft:sulfur_cube".into();
+        ty.species = crate::mobs::Species::SulfurCube;
+        let types = [("minecraft:sulfur_cube".into(), kind)].into();
+        let raw = Tag::compound([
+            ("id", string("minecraft:sulfur_cube")),
+            ("Pos", doubles(&[4.5, 220.0, 4.5])),
+            (
+                "equipment",
+                Tag::compound([(
+                    "body",
+                    Tag::compound([
+                        ("id", string("minecraft:oak_planks")),
+                        ("count", Tag::Int(1)),
+                    ]),
+                )]),
+            ),
+        ]);
+        let mut m = mob_from_nbt(&raw, &types, 1, None).unwrap();
+        assert_eq!(m.extra.body.as_deref(), Some("minecraft:oak_planks"));
+        m.extra.body = None;
+        let saved = mob_to_nbt(&m, [0; 4], Some(&raw), None, |_| None);
+        assert!(saved.get("equipment").is_none(), "{saved:?}");
+    }
+
     /// A wolf loads its armor (`equipment.body`) into the body slot with the
     /// durability it lost, and a helmet next to it into the head slot.
     #[test]
@@ -5514,6 +5567,34 @@ mod tests {
         }
     }
 
+    /// `Goat` reads `HasLeftHorn` and `HasRightHorn` with `getBooleanOr(key,
+    /// true)`: a number is true when its byte value is not 0, so an int 256
+    /// (byte 0) is a lost horn, as `0b` is.
+    #[test]
+    fn a_goats_horn_flags_are_read_as_bytes() {
+        let mut kind = crate::mobs::sensor_scan_tests::kind();
+        let ty = Arc::make_mut(&mut kind);
+        ty.id = "minecraft:goat".into();
+        ty.species = crate::mobs::Species::Goat;
+        let types = [("minecraft:goat".into(), kind)].into();
+        let lost = |left: Option<Tag>| {
+            let mut fields = vec![
+                ("id", string("minecraft:goat")),
+                ("Pos", doubles(&[4.5, 220.0, 4.5])),
+            ];
+            fields.extend(left.map(|v| ("HasLeftHorn", v)));
+            mob_from_nbt(&Tag::compound(fields), &types, 1, None)
+                .unwrap()
+                .extra
+                .lost_horns
+        };
+        assert_eq!(lost(None), [false, false]);
+        assert_eq!(lost(Some(Tag::Byte(1))), [false, false]);
+        assert_eq!(lost(Some(Tag::Byte(0))), [true, false]);
+        assert_eq!(lost(Some(Tag::Int(256))), [true, false]);
+        assert_eq!(lost(Some(Tag::Int(257))), [false, false]);
+    }
+
     #[test]
     fn non_mob_saves_drop_mob_flags_without_losing_entity_fields() {
         let uuid = [104, 0, 0, 1];
@@ -8003,6 +8084,14 @@ mod fireball_nbt_tests {
             ("Facing", Tag::Byte(1)),
         ]);
         assert_eq!(item_frame_from_nbt(&frame, 1).unwrap().pos, [-1, 80, 6]);
+        // BlockAttachedEntity.readAdditionalSaveData: a block_pos 16 blocks or
+        // more from the Pos block is refused for that block.
+        let mut far = painting.clone();
+        put(&mut far, "block_pos", Tag::IntArray(vec![28, 80, 22]));
+        assert_eq!(painting_from_nbt(&far).map(|p| p.0), Some([28, 80, 6]));
+        let mut near = painting.clone();
+        put(&mut near, "block_pos", Tag::IntArray(vec![28, 80, 21]));
+        assert_eq!(painting_from_nbt(&near).map(|p| p.0), Some([28, 80, 21]));
     }
 
     #[test]

crates/horizon-client/src/entity_nbt/hanging.rs

@@ -13,7 +13,8 @@ fn loaded_pitch(raw: Option<&Tag>) -> f32 {
         0.0
     }
 }
-/// Painting.addAdditionalSaveData: `facing`, `variant` and `block_pos`.
+/// Painting.addAdditionalSaveData: `facing`, `variant` and `block_pos`, after
+/// Entity.saveWithoutId's common fields.
 pub fn painting_to_nbt(p: &Painting, uuid: [i32; 4], raw: Option<&Tag>) -> Tag {
     let (lo, hi) = p.bounds();
     let base = Base {
@@ -26,8 +27,12 @@ pub fn painting_to_nbt(p: &Painting, uuid: [i32; 4], raw: Option<&Tag>) -> Tag {
         ),
         motion: Vec3::ZERO,
         rotation: [f32::from(p.facing) * 90.0, loaded_pitch(raw)],
-        on_ground: false,
-        fall_distance: 0.0,
+        // BlockAttachedEntity.tick never moves a painting (nor runs baseTick), so its
+        // onGround and fallDistance stay the ones Entity.load read.
+        on_ground: raw.is_some_and(|raw| flag(raw, "OnGround")),
+        fall_distance: raw
+            .and_then(|raw| float(raw.get("fall_distance")))
+            .unwrap_or(0.0),
     };
     let mut tag = base.tag(raw);
     put(&mut tag, "facing", Tag::Byte(p.facing as i8));
@@ -35,21 +40,37 @@ pub fn painting_to_nbt(p: &Painting, uuid: [i32; 4], raw: Option<&Tag>) -> Tag {
     put(&mut tag, "block_pos", Tag::IntArray(p.pos.to_vec()));
     tag
 }
-/// `BlockAttachedEntity.readAdditionalSaveData`: `block_pos` when saved; a
-/// summoned one has none, and `setPos` puts its block at the block holding
-/// the summon position.
+/// `BlockAttachedEntity.readAdditionalSaveData`: `block_pos` when saved and
+/// closer than 16 blocks to the block holding `Pos`; else (a summoned one
+/// has none) `setPos` puts it at that block.
 fn attached_block_pos(tag: &Tag) -> Option<[i32; 3]> {
-    match tag.get("block_pos") {
+    let stored = match tag.get("block_pos") {
         Some(Tag::IntArray(v)) if v.len() == 3 => Some([v[0], v[1], v[2]]),
-        _ => {
-            let at = position(tag)?;
-            Some([
-                at.x.floor() as i32,
-                at.y.floor() as i32,
-                at.z.floor() as i32,
-            ])
-        }
-    }
+        _ => None,
+    };
+    let Some(at) = position(tag) else {
+        return stored;
+    };
+    let here = [
+        at.x.floor() as i32,
+        at.y.floor() as i32,
+        at.z.floor() as i32,
+    ];
+    // Vec3i.closerThan(blockPosition(), 16): the squared distance under 256.
+    let near = |p: &[i32; 3]| {
+        (0..3)
+            .map(|i| (f64::from(p[i]) - f64::from(here[i])).powi(2))
+            .sum::<f64>()
+            < 256.0
+    };
+    Some(stored.filter(near).unwrap_or(here))
+}
+/// The block position and facing of a saved painting (`HangingEntity`'s
+/// `facing`, a 2D direction).
+pub fn painting_placement_from_nbt(tag: &Tag) -> Option<([i32; 3], u8)> {
+    let pos = attached_block_pos(tag)?;
+    let facing = wrap_data_value(number(tag.get("facing")).unwrap_or(0), 4);
+    Some((pos, facing))
 }
 /// `Direction.from3DDataValue` / `from2DDataValue`: the byte read by
 /// `LEGACY_ID_CODEC` indexes the table as `abs(data % modulus)`, never clamped.
@@ -59,8 +80,7 @@ fn wrap_data_value(raw: impl TryInto<i64> + Copy, modulus: i64) -> u8 {
 }
 /// The block position, facing and variant (if saved) of a painting.
 pub fn painting_from_nbt(tag: &Tag) -> Option<([i32; 3], u8, Option<String>)> {
-    let pos = attached_block_pos(tag)?;
-    let facing = wrap_data_value(number(tag.get("facing")).unwrap_or(0), 4);
+    let (pos, facing) = painting_placement_from_nbt(tag)?;
     Some((pos, facing, text(tag.get("variant"))))
 }
 /// ItemFrame.addAdditionalSaveData.
@@ -74,10 +94,14 @@ pub fn item_frame_to_nbt(f: &ItemFrame, uuid: [i32; 4], raw: Option<&Tag>) -> Ta
             (lo[1] + hi[1]) / 2.0,
             (lo[2] + hi[2]) / 2.0,
         ),
-        motion: Vec3::ZERO,
+        // BlockAttachedEntity.tick never runs super.tick, so the Motion, onGround and
+        // fallDistance that Entity.load read stay.
+        motion: raw.map_or(Vec3::ZERO, loaded_motion),
         rotation: [0.0, 0.0],
-        on_ground: false,
-        fall_distance: 0.0,
+        on_ground: raw.is_some_and(|raw| flag(raw, "OnGround")),
+        fall_distance: raw
+            .and_then(|raw| float(raw.get("fall_distance")))
+            .unwrap_or(0.0),
     };
     let mut tag = base.tag(raw);
     // `Entity.saveWithoutId`: `CustomName` before the frame's own fields.
@@ -148,4 +172,27 @@ mod tests {
         ]);
         assert_eq!(painting_from_nbt(&tag).unwrap().1, 1);
     }
+
+    #[test]
+    fn item_frame_keeps_loaded_motion_on_ground_and_fall_distance() {
+        let tag = Tag::compound([
+            ("id", string("minecraft:item_frame")),
+            ("Pos", doubles(&[0.5, 64.0, 0.5])),
+            ("Facing", Tag::Byte(2)),
+            ("Motion", doubles(&[0.5, 20.0, -0.25])),
+            ("OnGround", Tag::Byte(1)),
+            ("fall_distance", Tag::Double(3.5f64.to_bits())),
+        ]);
+        let frame = item_frame_from_nbt(&tag, 1).unwrap();
+        let saved = item_frame_to_nbt(&frame, [1, 2, 3, 4], Some(&tag));
+        // A component beyond 10 loads as 0, the others stay.
+        assert_eq!(motion(&saved), Vec3::new(0.5, 0.0, -0.25));
+        assert!(flag(&saved, "OnGround"));
+        assert_eq!(float(saved.get("fall_distance")), Some(3.5));
+        // A frame made in play has nothing loaded: zeros.
+        let made = item_frame_to_nbt(&frame, [1, 2, 3, 4], None);
+        assert_eq!(motion(&made), Vec3::ZERO);
+        assert!(!flag(&made, "OnGround"));
+        assert_eq!(float(made.get("fall_distance")), Some(0.0));
+    }
 }

crates/horizon-client/src/flatgen.rs

@@ -317,6 +317,12 @@ pub fn settings_from_json(
 impl ChunkGenerator for FlatTerrain {
     type Worker = ();
     fn worker(&self) {}
+    /// FlatLevelSource's proto is already its decorated column. Keep a copy
+    /// for lighting a finished neighbour outside the kept area, just as the
+    /// vanilla pipeline does for FEATURES neighbours.
+    fn light_view(&self, proto: &crate::streaming::Proto) -> Option<Chunk> {
+        proto.downcast_ref::<Chunk>().cloned()
+    }
     fn lod_surface(&self, _: &mut (), _: i32, _: i32) -> Option<crate::lod::Surface> {
         self.surface
     }
@@ -610,4 +616,21 @@ mod tests {
             .is_none()
         );
     }
+
+    #[test]
+    fn light_view_keeps_a_flat_proto_column() {
+        let terrain = FlatTerrain {
+            shape: LevelShape::OVERWORLD,
+            layers: Vec::new(),
+            biome: 0,
+            surface: None,
+            void_platform: None,
+        };
+        let mut chunk = Chunk::empty(3, -4);
+        chunk.set(0, 0, 0, 42);
+        let proto: crate::streaming::Proto = Box::new(chunk);
+        let view = terrain.light_view(&proto).expect("flat proto light view");
+        assert_eq!((view.x, view.z), (3, -4));
+        assert_eq!(view.block(0, 0, 0).0, 42);
+    }
 }

crates/horizon-client/src/game.rs

@@ -476,7 +476,6 @@ mod trial_spawner;
 mod trial_visuals;
 mod trident;
 mod tutorial;
-mod tweaks;
 mod ui_control;
 mod use_hand;
 mod using_item;
@@ -2230,7 +2229,7 @@ struct Game<'a> {
     /// `AbstractContainerScreen`'s quick craft and skip-release state.
     inv_clicks: horizon_client::container_screen::Clicks,
     /// The Mouse Tweaks extra's drag and wheel (`tweaks`).
-    tweaks: tweaks::Tweaks,
+    tweaks: extras::mouse_tweaks::Tweaks,
     /// The wheel and hovered slot of `BundleMouseActions`.
     bundle_mouse: bundles::BundleMouse,
     /// The last inventory click, for the double click that gathers a stack.
@@ -7211,14 +7210,14 @@ impl Game<'_> {
         laps.lap("eg_objects");
         // Particles (ParticleEngine.extract): camera-facing quads.
         self.mark_stage(out.len(), "PARTICLES");
-        let world = &self.world;
         let particle_mode = self.settings.horizon.particle_culling;
         if particle_mode == horizon_client::graphics::ParticleCullingMode::Off {
-            self.particles.render(
+            self.particles.render_in_view(
                 camera,
                 self.particle_rotation(),
                 alpha as f32,
-                &|b| world.light(b[0], b[1], b[2]),
+                self.view_frustum.as_ref(),
+                &|b| self.world.light(b[0], b[1], b[2]),
                 &mut out,
             );
         } else {
@@ -7241,7 +7240,7 @@ impl Game<'_> {
                     true,
                     frustum.as_ref(),
                     &mut |min, max| particle_culling.hidden(min, max),
-                    &|b| world.light(b[0], b[1], b[2]),
+                    &|b| self.world.light(b[0], b[1], b[2]),
                     &mut out,
                 );
             }
@@ -8189,19 +8188,16 @@ impl Game<'_> {
                     .ok_or("missing lit block state")?;
                 state.properties.insert("lit".into(), "true".into());
                 self.level_set(hit.pos, registry.resolve(&state)?)?;
-                self.audio.play(
-                    if item == "fire_charge" {
-                        "minecraft:item.firecharge.use"
-                    } else {
-                        "minecraft:item.flintandsteel.use"
-                    },
-                    Some(at(hit.pos)),
-                    1.0,
-                    horizon_client::items::fire_starter_pitch(
-                        item == "fire_charge",
-                        &mut self.world.random,
-                    ),
+                let sound = if item == "fire_charge" {
+                    "minecraft:item.firecharge.use"
+                } else {
+                    "minecraft:item.flintandsteel.use"
+                };
+                let pitch = horizon_client::items::fire_starter_pitch(
+                    item == "fire_charge",
+                    &mut self.world.random,
                 );
+                self.play_block_use_sound(sound, at(hit.pos), pitch);
                 // FlintAndSteelItem / FireChargeItem.useOn: BLOCK_CHANGE at the lit block,
                 // and ItemStack.useOn's used statistic.
                 self.post_block_game_event(
@@ -8232,7 +8228,7 @@ impl Game<'_> {
                     item == "fire_charge",
                     &mut self.world.random,
                 );
-                self.audio.play(sound, Some(at(target)), 1.0, pitch);
+                self.play_block_use_sound(sound, at(target), pitch);
                 // BLOCK_PLACE: flint and steel names the clicked block, a fire charge the
                 // fire. Then ItemStack.useOn's used statistic.
                 let placed_at = if item == "fire_charge" {
@@ -12590,6 +12586,35 @@ mod subtitles;
 #[cfg(test)]
 #[path = "game_tests.rs"]
 mod tests;
+#[cfg(test)]
+mod test_neighbourhood {
+    //! Shared fixture step for tests that tick entities on prepared data.
+    use super::*;
+
+    impl Game<'_> {
+        /// Loads the chunks within 2 columns of `(cx, cz)` that are not loaded yet.
+        /// Entity ticking waits for every chunk in that 5x5 neighbourhood
+        /// (`ChunkMap.prepareEntityTickingChunk`), so a fixture that ticks mobs,
+        /// items or TNT in a chunk calls this after setting up its own chunks.
+        pub(crate) fn load_ticking_neighbourhood(&mut self, cx: i32, cz: i32) {
+            for z in cz - 2..=cz + 2 {
+                for x in cx - 2..=cx + 2 {
+                    if self.world.chunks.contains_key(&(x, z)) {
+                        continue;
+                    }
+                    self.world.chunks.insert(
+                        (x, z),
+                        std::sync::Arc::new(horizon_client::chunk::Chunk::empty(x, z)),
+                    );
+                    // A chunk that is already registered keeps its ticks.
+                    let _ = self
+                        .block_ticks
+                        .add_empty_chunk(horizon_core::position::ChunkPos::new(x, z));
+                }
+            }
+        }
+    }
+}
 
 fn write_level_for_role(
     level: &mut Level,

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

@@ -51,6 +51,7 @@ fn game() -> Game<'static> {
     game.block_ticks
         .add_empty_chunk(ChunkPos::new(0, 0))
         .unwrap();
+    game.load_ticking_neighbourhood(0, 0);
     for command in [
         "forceload add 0 0",
         "fill 0 99 0 15 99 15 stone",

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

@@ -2709,6 +2709,7 @@ mod postbaseline_lodestone_controls {
         game.block_ticks
             .add_empty_chunk(BlockPos::new(64, 0, 64).chunk())
             .unwrap();
+        game.load_ticking_neighbourhood(0, 0);
         assert!(game.run_command("fill 64 199 64 79 199 79 stone"));
         assert!(game.run_command(&format!("summon armor_stand 65.5 200.0 65.5 {{UUID:[I;42321,0,0,102],Health:20f,NoGravity:1b,equipment:{{mainhand:{}}}}}",item("minecraft:compass",tracked,100,1))));
         let id = |n| {

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

@@ -1508,7 +1508,6 @@ impl Game<'_> {
             Vec3::new(b.position.x, top, b.position.z)
         }
     }
-    /// `BoatItem.use`: aim at a block or the water surface.
     /// `Entity.setYRot` on a boat just made (its old rotation moves with it).
     pub(super) fn set_boat_yaw(&mut self, id: u32, yaw: f32) {
         if let Some(b) = self.boats.iter_mut().find(|b| b.id == id) {
@@ -1516,6 +1515,7 @@ impl Game<'_> {
             b.previous_yaw = yaw;
         }
     }
+    /// `BoatItem.use`: aim at a block or the water surface.
     pub(super) fn place_boat(&mut self, stack: &ItemStack) -> bool {
         let Some(boat) = self.boat_to_place(stack) else {
             return false;
@@ -1528,7 +1528,7 @@ impl Game<'_> {
         self.world.modified.insert(key);
         let (id, kind, yaw) = (boat.id, boat.entity_type(), boat.yaw);
         self.boats.push(boat);
-        self.apply_vehicle_stack_config(super::commands::Target::Boat(id), &kind, stack, true);
+        self.apply_item_stack_config(super::commands::Target::Boat(id), &kind, stack, true);
         // BoatItem.use: setYRot(player.getYRot()) after the stack's config.
         self.set_boat_yaw(id, yaw);
         if self.serving.is_some() || self.options.dedicated.is_some() {

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

@@ -54,6 +54,9 @@ fn game() -> Game<'static> {
             .chunks
             .insert((x, 0), Arc::new(Chunk::empty(x, 0)));
     }
+    for x in 0..2 {
+        game.load_ticking_neighbourhood(x, 0);
+    }
     assert!(game.run_command("fill 0 99 0 31 99 15 stone"));
     game.player = Some(PlayerMotion::new(game.motion, Vec3::new(4.5, 100.0, 6.5)).unwrap());
     let net = NetConfig {

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

@@ -4,6 +4,7 @@ mod admin;
 pub(super) mod compute;
 mod data;
 mod display_names;
+mod target_position;
 pub(super) use data::place_summoned;
 mod effects;
 pub(super) mod execute;
@@ -451,9 +452,7 @@ impl Game<'_> {
         // the server's own source, "Server".
         let who = match self.command_source.and_then(|s| s.entity) {
             Some(entity) => self.target_name(entity),
-            None if self.console_broadcast.is_some() => {
-                Text::literal(if self.rcon_source { "Rcon" } else { "Server" }.to_owned())
-            }
+            None if self.console_broadcast.is_some() => self.server_name(),
             None => self.player_display_name(),
         };
         let line = Text::translate("chat.type.admin", &[who, message])
@@ -538,118 +537,6 @@ impl Game<'_> {
         conn.and_then(|c| self.command_guest(c))
             .map_or(self.dim, |g| Dim::from_id(&g.dimension))
     }
-    pub(super) fn target_position(&self, t: Target) -> Option<[f64; 3]> {
-        match t {
-            Target::Player => self
-                .player
-                .as_ref()
-                .map(|p| [p.position.x, p.position.y, p.position.z]),
-            Target::Guest(conn) => self.command_guest(conn).map(|g| g.position),
-            Target::Mob(id) => self
-                .mobs
-                .iter()
-                .find(|m| m.id == id)
-                .map(|m| [m.position.x, m.position.y, m.position.z]),
-            Target::Item(id) => self
-                .dropped
-                .iter()
-                .find(|i| i.id == id)
-                .map(|i| [i.position.x, i.position.y, i.position.z]),
-            Target::Orb(id) => self
-                .orbs
-                .iter()
-                .find(|o| o.id == id)
-                .map(|o| [o.position.x, o.position.y, o.position.z]),
-            Target::Projectile(id) => self
-                .creatures
-                .projectiles
-                .iter()
-                .find(|a| a.id == id)
-                .map(|a| [a.position.x, a.position.y, a.position.z]),
-            Target::Stand(id) => self
-                .armor_stands
-                .iter()
-                .find(|a| a.id == id)
-                .map(|a| [a.position.x, a.position.y, a.position.z]),
-            Target::Frame(id) => self.item_frames.iter().find(|f| f.id == id).map(|f| {
-                let (lo, hi) = f.bounds();
-                [
-                    (lo[0] + hi[0]) / 2.0,
-                    (lo[1] + hi[1]) / 2.0,
-                    (lo[2] + hi[2]) / 2.0,
-                ]
-            }),
-            Target::Painting(id) => self.paintings.iter().find(|p| p.id == id).map(|p| {
-                let (lo, hi) = p.bounds();
-                [
-                    (lo[0] + hi[0]) / 2.0,
-                    (lo[1] + hi[1]) / 2.0,
-                    (lo[2] + hi[2]) / 2.0,
-                ]
-            }),
-            Target::Boat(id) => self
-                .boats
-                .iter()
-                .find(|b| b.id == id)
-                .map(|b| [b.position.x, b.position.y, b.position.z]),
-            Target::Cart(id) => self
-                .carts
-                .iter()
-                .find(|c| c.id == id)
-                .map(|c| [c.position.x, c.position.y, c.position.z]),
-            Target::Other(id) => self
-                .others
-                .iter()
-                .find(|o| o.id == id)
-                .map(|o| [o.position.x, o.position.y, o.position.z]),
-            Target::Crystal(id) => self
-                .crystals
-                .iter()
-                .find(|c| c.id == id)
-                .map(|c| [c.position.x, c.position.y, c.position.z]),
-            Target::Dragon(id) => self
-                .dragon
-                .as_ref()
-                .filter(|d| d.id == id)
-                .map(|d| [d.position.x, d.position.y, d.position.z]),
-            Target::Cushion(id) => self
-                .cushions
-                .iter()
-                .find(|c| c.id == id)
-                .map(|c| [c.position.x, c.position.y, c.position.z]),
-            Target::Tnt(id) => self
-                .tnts
-                .iter()
-                .find(|t| t.id == id)
-                .map(|t| [t.position.x, t.position.y, t.position.z]),
-            Target::Falling(id) => self
-                .falling
-                .iter()
-                .find(|f| f.id == id)
-                .map(|f| [f.position.x, f.position.y, f.position.z]),
-            Target::Rocket(id) => self
-                .rockets
-                .iter()
-                .find(|r| r.id == id)
-                .map(|r| [r.position.x, r.position.y, r.position.z]),
-            Target::Cloud(id) => self.breath_clouds.iter().find(|c| c.id == id).map(|c| c.at),
-            Target::Trident(id) => self
-                .tridents
-                .iter()
-                .find(|t| t.id == id)
-                .map(|t| [t.position.x, t.position.y, t.position.z]),
-            Target::Fangs(id) => self.fangs.list.iter().find(|f| f.id == id).map(|f| f.pos),
-            Target::Spawner(id) => self
-                .ominous_spawners
-                .iter()
-                .find(|s| s.id == id)
-                .map(|s| s.position),
-            Target::Knot(id) => self.natural_knot(id).map(|fence| {
-                let p = horizon_client::mobs::leash::knot_state(fence).position;
-                [p.x, p.y, p.z]
-            }),
-        }
-    }
     pub(super) fn target_type(&self, t: Target) -> String {
         match t {
             Target::Player | Target::Guest(_) => "minecraft:player".into(),
@@ -1851,7 +1738,7 @@ impl Game<'_> {
             }
             Target::Crystal(id) => {
                 if let Some(c) = self.crystals.iter_mut().find(|c| c.id == id) {
-                    c.position = v;
+                    (c.position, c.fall.0) = (v, true); // performTeleport: setOnGround(true)
                 }
             }
             Target::Dragon(id) => {
@@ -1862,6 +1749,8 @@ impl Game<'_> {
             }
             Target::Tnt(id) => {
                 if let Some(t) = self.tnts.iter_mut().find(|t| t.id == id) {
+                    // `PrimedTnt.teleport` includes same-level command teleports.
+                    t.used_portal = true;
                     t.position = v;
                     t.previous = v;
                     if let Some(r) = rotation {
@@ -2635,14 +2524,9 @@ impl Game<'_> {
                     self.next_entity += 1;
                     let at = Vec3::new(pos[0], pos[1], pos[2]);
                     let drawn = self.world.random.next_int_bound(100_000).unwrap_or(0);
-                    self.crystals.push(super::dragon::Crystal {
-                        id: self.next_entity,
-                        position: at,
-                        show_bottom: true,
-                        time: super::dragon::Crystal::start_time(at, drawn, self.clock.still()),
-                        beam: None,
-                        invulnerable: false,
-                    });
+                    let time = super::dragon::Crystal::start_time(at, drawn, self.clock.still());
+                    let crystal = super::dragon::Crystal::new(self.next_entity, at, true, time);
+                    self.crystals.push(crystal);
                     // tryAddFreshEntityWithPassengers refused: ERROR_DUPLICATE_UUID.
                     if !self.native_joins_flush(false, self.next_entity) {
                         return Err(err("commands.summon.failed.uuid", &[]));
@@ -4412,7 +4296,7 @@ impl Game<'_> {
                                 .map(|cart| cart.command.name())
                         })
                     })
-                    .unwrap_or_else(|| Text::literal("Server")),
+                    .unwrap_or_else(|| self.server_name()),
             },
             None => self.player_display_name(),
         };

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

@@ -697,6 +697,27 @@ impl Game<'_> {
                 self.carts[i] = cart;
                 set_key(&mut tag, "UUID", Tag::IntArray(uuid.to_vec()));
             }
+            Target::Painting(id) => {
+                // Painting.readAdditionalSaveData over HangingEntity's: the
+                // facing, the block it hangs on and a known variant
+                // (`VariantUtils.readVariant(..).ifPresent`: an unknown or
+                // unreadable one keeps the painting's).
+                let uuid = self.uuid_for(id);
+                let (pos, facing) =
+                    entity_nbt::painting_placement_from_nbt(&tag).ok_or_else(stale)?;
+                let known = entity_nbt::painting_from_nbt(&tag)
+                    .and_then(|(_, _, v)| self.painting_variants.get(&v?).cloned());
+                let p = self
+                    .paintings
+                    .iter_mut()
+                    .find(|p| p.id == id)
+                    .ok_or_else(stale)?;
+                (p.pos, p.facing) = (pos, facing);
+                if let Some(v) = known {
+                    (p.variant, p.width, p.height) = (v.id, v.width, v.height);
+                }
+                set_key(&mut tag, "UUID", Tag::IntArray(uuid.to_vec()));
+            }
             Target::Other(id) => {
                 let uuid = self.uuid_for(id);
                 let marker = self
@@ -748,6 +769,7 @@ impl Game<'_> {
         | Target::Item(id)
         | Target::Stand(id)
         | Target::Frame(id)
+        | Target::Painting(id)
         | Target::Boat(id)
         | Target::Cart(id)
         | Target::Tnt(id)
@@ -1545,7 +1567,7 @@ impl Game<'_> {
         let before = self.next_entity;
         let mut tag = tag;
         crate::game::persist::mark_fresh(&mut tag);
-        self.world.loaded_entities.push((key, vec![tag]));
+        self.world.queue_entity_nbt(key, vec![tag]);
         self.spawn_loaded_entities();
         waiting.append(&mut self.world.loaded_entities);
         self.world.loaded_entities = waiting;

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

@@ -61,6 +61,12 @@ impl Game<'_> {
             .unwrap_or(Target::Player)
     }
 
+    /// The name of the server's own source: "Rcon" for a command an RCON client sent
+    /// (`RconConsoleSource`), "Server" otherwise (`MinecraftServer.createCommandSourceStack`).
+    pub(in crate::game) fn server_name(&self) -> Text {
+        Text::literal(if self.rcon_source { "Rcon" } else { "Server" })
+    }
+
     /// `PlayerList.getPlayerByName`: names are not case sensitive. Horizon:
     /// on a server where a mod gave players nicknames
     /// (`native_set_nickname`), a name no player has finds the player going

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

@@ -0,0 +1,116 @@
+use super::{Game, Target};
+
+impl Game<'_> {
+    pub(in crate::game) fn target_position(&self, t: Target) -> Option<[f64; 3]> {
+        match t {
+            Target::Player => self
+                .player
+                .as_ref()
+                .map(|p| [p.position.x, p.position.y, p.position.z]),
+            Target::Guest(conn) => self.command_guest(conn).map(|g| g.position),
+            Target::Mob(id) => self
+                .mobs
+                .iter()
+                .find(|m| m.id == id)
+                .map(|m| [m.position.x, m.position.y, m.position.z]),
+            Target::Item(id) => self
+                .dropped
+                .iter()
+                .find(|i| i.id == id)
+                .map(|i| [i.position.x, i.position.y, i.position.z]),
+            Target::Orb(id) => self
+                .orbs
+                .iter()
+                .find(|o| o.id == id)
+                .map(|o| [o.position.x, o.position.y, o.position.z]),
+            Target::Projectile(id) => self
+                .creatures
+                .projectiles
+                .iter()
+                .find(|a| a.id == id)
+                .map(|a| [a.position.x, a.position.y, a.position.z]),
+            Target::Stand(id) => self
+                .armor_stands
+                .iter()
+                .find(|a| a.id == id)
+                .map(|a| [a.position.x, a.position.y, a.position.z]),
+            Target::Frame(id) => self.item_frames.iter().find(|f| f.id == id).map(|f| {
+                let (lo, hi) = f.bounds();
+                [
+                    (lo[0] + hi[0]) / 2.0,
+                    (lo[1] + hi[1]) / 2.0,
+                    (lo[2] + hi[2]) / 2.0,
+                ]
+            }),
+            Target::Painting(id) => self.paintings.iter().find(|p| p.id == id).map(|p| {
+                let (lo, hi) = p.bounds();
+                [
+                    (lo[0] + hi[0]) / 2.0,
+                    (lo[1] + hi[1]) / 2.0,
+                    (lo[2] + hi[2]) / 2.0,
+                ]
+            }),
+            Target::Boat(id) => self
+                .boats
+                .iter()
+                .find(|b| b.id == id)
+                .map(|b| [b.position.x, b.position.y, b.position.z]),
+            Target::Cart(id) => self
+                .carts
+                .iter()
+                .find(|c| c.id == id)
+                .map(|c| [c.position.x, c.position.y, c.position.z]),
+            Target::Other(id) => self
+                .others
+                .iter()
+                .find(|o| o.id == id)
+                .map(|o| [o.position.x, o.position.y, o.position.z]),
+            Target::Crystal(id) => self
+                .crystals
+                .iter()
+                .find(|c| c.id == id)
+                .map(|c| [c.position.x, c.position.y, c.position.z]),
+            Target::Dragon(id) => self
+                .dragon
+                .as_ref()
+                .filter(|d| d.id == id)
+                .map(|d| [d.position.x, d.position.y, d.position.z]),
+            Target::Cushion(id) => self
+                .cushions
+                .iter()
+                .find(|c| c.id == id)
+                .map(|c| [c.position.x, c.position.y, c.position.z]),
+            Target::Tnt(id) => self
+                .tnts
+                .iter()
+                .find(|t| t.id == id)
+                .map(|t| [t.position.x, t.position.y, t.position.z]),
+            Target::Falling(id) => self
+                .falling
+                .iter()
+                .find(|f| f.id == id)
+                .map(|f| [f.position.x, f.position.y, f.position.z]),
+            Target::Rocket(id) => self
+                .rockets
+                .iter()
+                .find(|r| r.id == id)
+                .map(|r| [r.position.x, r.position.y, r.position.z]),
+            Target::Cloud(id) => self.breath_clouds.iter().find(|c| c.id == id).map(|c| c.at),
+            Target::Trident(id) => self
+                .tridents
+                .iter()
+                .find(|t| t.id == id)
+                .map(|t| [t.position.x, t.position.y, t.position.z]),
+            Target::Fangs(id) => self.fangs.list.iter().find(|f| f.id == id).map(|f| f.pos),
+            Target::Spawner(id) => self
+                .ominous_spawners
+                .iter()
+                .find(|s| s.id == id)
+                .map(|s| s.position),
+            Target::Knot(id) => self.natural_knot(id).map(|fence| {
+                let p = horizon_client::mobs::leash::knot_state(fence).position;
+                [p.x, p.y, p.z]
+            }),
+        }
+    }
+}

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

@@ -1080,7 +1080,7 @@ impl Game<'_> {
             max_entity_cramming: self.ui.rules.int("max_entity_cramming"),
             dimension_type: self.dimension_type(),
             world_seed: self.level.seed,
-            sea_level: if self.dim == Dim::Nether { 32 } else { 63 },
+            sea_level: horizon_world::level::sea_level_of(self.level_key()),
             teams: std::sync::Arc::new(self.mob_teams()),
             items: Some(self.items()),
             lid_openers: &self.lid_openers,
@@ -1280,10 +1280,9 @@ impl Game<'_> {
                     .is_some()
                     .then_some(self.level.player_uuid)
                     .flatten(),
-                mods: round.listening() || !horizon_client::mod_api::mods().is_empty(),
                 ticking: &|| Box::new(self.entity_ticking_area()),
             };
-            let mut group = match islands.plan(&mobs, &snapshot, &turns) {
+            let mut group = match islands.plan(&mobs, &snapshot, &turns, &start) {
                 Some(plan) => islands.run(plan, mobs.into(), snapshot, start, &mut turns, &shared),
                 None => {
                     let mut group = mob_group::Group::new(mobs.into(), snapshot, start);
@@ -1878,10 +1877,9 @@ impl Game<'_> {
         for item in stacks {
             // Every death drop is its own ItemEntity, and the drop entity's
             // own random (not the level's) gives it the constructor's
-            // horizontal push (its motion otherwise stays [0, 0.2, 0] and
-            // the drops land stacked at the mob's centre, without disturbing
-            // the level random that the orbs' merge ids and block ticks read
-            // next).
+            // horizontal push (its motion otherwise stays [0, 0.2, 0] and the
+            // drops land stacked at the mob's centre, without disturbing the
+            // level random that the orbs' merge ids and block ticks read next).
             self.spawn_item_own(item, pos, 10);
         }
         // LivingEntity.dropExperience: a mod may change the mob's experience
@@ -1921,8 +1919,9 @@ impl Game<'_> {
                         self.spawn_item_own(item, pos, 10);
                     }
                 }
+                drops::Drop::Aged(s, age) => self.spawn_item_aged(from_loot(&s), pos, age),
                 drops::Drop::Orb(value) if !consumed => self.spawn_orbs(pos, value as u32),
-                drops::Drop::Item(_) | drops::Drop::Stack(_) | drops::Drop::Orb(_) => {}
+                _ => {}
             }
         }
     }
@@ -3234,11 +3233,7 @@ impl Game<'_> {
                 MobEvent::DolphinTreasure { mob } => {
                     // ServerLevel.findNearestMapStructure(#dolphin_located, 50).
                     let Some(at) = self.mobs.iter().find(|m| m.id == mob).map(|m| {
-                        [
-                            m.position.x.floor() as i32,
-                            m.position.y.floor() as i32,
-                            m.position.z.floor() as i32,
-                        ]
+                        [m.position.x, m.position.y, m.position.z].map(|v| v.floor() as i32)
                     }) else {
                         continue;
                     };
@@ -3249,7 +3244,11 @@ impl Game<'_> {
                         .filter(|_| !names.is_empty())
                         .and_then(|t| t.locate(&names, at, 50));
                     if let Some(m) = self.mobs.iter_mut().find(|m| m.id == mob) {
-                        m.extra.home = found.map(|(_, p)| p);
+                        m.extra.home = found.as_ref().map(|(_, p)| *p);
+                    }
+                    // DolphinSwimToTreasureGoal.start: entity event 38 once it has a treasure.
+                    if found.is_some() {
+                        self.mob_event_particles(mob, 38);
                     }
                 }
                 MobEvent::EffectPlayer {
@@ -9051,6 +9050,7 @@ mod h169_glide_travel_tests {
                     .unwrap();
             }
         }
+        game.load_ticking_neighbourhood(0, 0);
         game.player = Some(PlayerMotion::new(game.motion, Vec3::new(2.5, 200.0, 2.5)).unwrap());
         game.creative = true;
         assert!(game.run_command("fill 0 199 0 31 199 31 stone"));

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

@@ -64,6 +64,9 @@ pub(super) struct Group<M: MobSlot> {
     pub corpses: Vec<Mob>,
     pub gone: Vec<Gone>,
     pub guest_events: Vec<(u32, u32, MobEvent)>,
+    /// The mod hooks its turns kept for the join, with each turn's place in the whole list (a
+    /// group of the parallel tick with mods loaded: `native_client_hooks::Deferred`).
+    pub deferred: Vec<(usize, horizon_client::native_client_hooks::Deferred)>,
 }
 
 /// What decides each turn besides the group, read at the turn as the serial loop reads it.
@@ -77,7 +80,7 @@ pub(super) struct Turns<'t, 'w> {
     /// The one player's position, when the level has one: every mob's nearest.
     pub single_player: Option<Option<Vec3>>,
     /// Whether a mod canceled a mob's tick.
-    pub canceled: &'t dyn Fn(u32) -> bool,
+    pub canceled: &'t (dyn Fn(u32) -> bool + Sync),
     /// `getCurrentDifficultyAt` a position.
     pub difficulty: &'t (dyn Fn([f64; 3]) -> LocalDifficulty + Sync),
     /// The last chunk's difficulty: mobs come in runs of one chunk.
@@ -137,6 +140,7 @@ impl<M: MobSlot> Group<M> {
             corpses: Vec::new(),
             gone: Vec::new(),
             guest_events: Vec::new(),
+            deferred: Vec::new(),
         }
     }
 
@@ -173,7 +177,17 @@ impl<M: MobSlot> Group<M> {
                 foreign.reader.set(at);
             }
             if let Some(foreign) = foreign {
-                foreign.in_seed_order(at, || self.turn(i, turns, shared));
+                foreign.in_seed_order(at, || {
+                    if foreign.defers {
+                        let ((), kept) =
+                            horizon_client::native_client_hooks::deferring_turn(|| {
+                                self.turn(i, turns, shared);
+                            });
+                        self.deferred.extend(kept.into_iter().map(|d| (at, d)));
+                    } else {
+                        self.turn(i, turns, shared);
+                    }
+                });
             } else {
                 self.turn(i, turns, shared);
             }
@@ -363,7 +377,10 @@ impl<M: MobSlot> Group<M> {
                 shared.guest_ids,
                 self.player.as_ref(),
             );
-            if let Some((player, mob)) = named {
+            // A grouped turn runs while no mod hooks the change (`horizon_mod_api_gen::mob_turn`).
+            if let Some((player, mob)) = named
+                && !horizon_client::native_client_hooks::deferring()
+            {
                 let kind = super::super::native_hooks::mob_kind(m);
                 let mut cancel = false;
                 Game::native_living_change_target(

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

@@ -5,9 +5,14 @@ use super::super::{
 };
 use horizon_client::{mobs::Species, scoreboard::teams_allow_damage};
 use horizon_core::geometry::Vec3;
+use horizon_protocol::packets::play::{Clientbound, GameEvent};
+
+/// `ClientboundGameEventPacket.PUFFER_FISH_STING`.
+const PUFFER_FISH_STING: u8 = 9;
 
 impl Game<'_> {
-    /// `Pufferfish.playerTouch`: accepted player damage, then poison with this fish as source.
+    /// `Pufferfish.playerTouch`: accepted player damage, the sting game event, then poison with
+    /// this fish as source.
     pub(in crate::game) fn touch_pufferfish(&mut self) {
         if self.remote.is_some() || self.spectator() {
             return;
@@ -46,10 +51,11 @@ impl Game<'_> {
                     m.extra.size,
                     [m.position.x, m.position.y, m.position.z],
                     self.mob_entity(m),
+                    m.silent,
                 )
             })
             .collect();
-        for (id, puff, at, source) in touching {
+        for (id, puff, at, source, silent) in touching {
             if !self.hurt_player_from(
                 (1 + puff) as f32,
                 Some(at),
@@ -58,6 +64,10 @@ impl Game<'_> {
             ) {
                 continue;
             }
+            // `if (!this.isSilent())` inside the `hurtServer` branch: before the poison.
+            if !silent {
+                self.puffer_fish_sting();
+            }
             let changes = self.potions.effects.changes;
             self.give_player_effect("minecraft:poison", 60 * puff, 0);
             if self.potions.effects.changes != changes {
@@ -65,4 +75,17 @@ impl Game<'_> {
             }
         }
     }
+    /// `ServerPlayer.connection.send(ClientboundGameEventPacket(PUFFER_FISH_STING, 0.0F))`: the
+    /// stung player's own client plays it (`ClientPacketListener.handleGameEvent`). A server has
+    /// no player of its own, so the packet is the only way to reach it.
+    fn puffer_fish_sting(&mut self) {
+        self.guest_packets.push(Clientbound::GameEvent(GameEvent {
+            event: PUFFER_FISH_STING,
+            param: 0.0,
+        }));
+    }
 }
+
+#[cfg(test)]
+#[path = "pufferfish_sting_tests.rs"]
+mod pufferfish_sting_tests;

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

@@ -0,0 +1,95 @@
+//! `Pufferfish.playerTouch`: the sting game event (`ClientboundGameEventPacket.PUFFER_FISH_STING`)
+//! goes out only inside the `hurtServer` branch, and only when the fish is not
+//! silent; the poison follows it.
+use crate::game::{Audio, Game, Options, Progress, Settings, execution_role, load_resources};
+use horizon_client::mobs::Mob;
+use horizon_client::motion::PlayerMotion;
+use horizon_core::geometry::Vec3;
+use horizon_protocol::packets::play::Clientbound;
+
+/// A game whose window player touches one puffed (state 2) pufferfish. The
+/// server acts for the guest `lan_acting`: `playerTouch` runs there, and the
+/// event it sends reaches that player's own client.
+fn game_with(silent: bool) -> Game<'static> {
+    let root = std::path::PathBuf::from(
+        std::env::var_os("HORIZON_TEST_RESOURCES")
+            .expect("set HORIZON_TEST_RESOURCES to prepared resources"),
+    );
+    let settings = Settings::default();
+    let loaded = load_resources(
+        root.clone(),
+        None,
+        &root,
+        &settings,
+        std::time::Instant::now(),
+        false,
+        false,
+        &Progress::new(),
+        &mut |_, _| unreachable!(),
+    )
+    .unwrap();
+    let mut options = Options::parse(std::iter::empty()).unwrap().unwrap();
+    options.resources = root.clone();
+    options.execution_role = execution_role::ExecutionRole::IntegratedServer;
+    let res: &'static _ = Box::leak(Box::new(loaded.resources));
+    let mut game = Game::new(
+        res,
+        loaded.pack,
+        loaded.gui.unwrap(),
+        options,
+        settings,
+        Audio::silent(&root),
+        None,
+    )
+    .unwrap();
+    game.creative = false;
+    game.lan_acting = Some(7);
+    game.player = Some(PlayerMotion::new(game.motion, Vec3::new(8.5, 66.0, 8.5)).unwrap());
+    let kind = game.res.mob_types()["minecraft:pufferfish"].clone();
+    let mut fish = Mob::new(9001, kind, Vec3::new(8.5, 66.0, 8.5), 0.0);
+    fish.extra.size = 2;
+    fish.silent = silent;
+    game.mobs.push(fish);
+    game
+}
+
+/// The game events the stung player's client was sent, as `(event, parameter)`.
+fn stings(game: &Game<'_>) -> Vec<(u8, f32)> {
+    game.guest_packets
+        .iter()
+        .filter_map(|packet| match packet {
+            Clientbound::GameEvent(e) => Some((e.event, e.param)),
+            _ => None,
+        })
+        .collect()
+}
+
+fn health(game: &Game<'_>) -> f32 {
+    game.player.as_ref().unwrap().health.health()
+}
+
+#[test]
+#[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
+fn the_sting_event_goes_out_once_per_accepted_hit() {
+    let mut g = game_with(false);
+    g.touch_pufferfish();
+    assert_eq!(health(&g), 17.0, "1 + PuffState 2 of damage landed");
+    assert_eq!(stings(&g), vec![(9, 0.0)], "PUFFER_FISH_STING, parameter 0");
+    let poison = g.potions.effects.get("poison").expect("poisoned");
+    assert_eq!((poison.duration, poison.amplifier), (120, 0));
+    // A second touch inside the hurt cooldown is refused (`hurtServer` is
+    // false): no damage and no event.
+    g.touch_pufferfish();
+    assert_eq!(health(&g), 17.0, "the cooldown refused the second hit");
+    assert_eq!(stings(&g).len(), 1, "a refused hit sends nothing");
+}
+
+#[test]
+#[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
+fn a_silent_fish_damages_and_poisons_without_the_sting() {
+    let mut g = game_with(true);
+    g.touch_pufferfish();
+    assert_eq!(health(&g), 17.0, "the damage still lands");
+    assert!(g.potions.effects.get("poison").is_some(), "the poison too");
+    assert!(stings(&g).is_empty(), "a silent fish sends no event");
+}

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

@@ -308,6 +308,17 @@ fn overload_warning(behind: Duration, tick: Duration) -> String {
     )
 }
 
+/// `ServerGamePacketListenerImpl.tick`'s idle kick: a player whose last action is more than
+/// `minutes` (`player-idle-timeout`, none when 0 or less) behind, counted here in ticks, is kicked,
+/// unless the End poem is showing (`ServerPlayer.wonGame`): its client sends no action until it
+/// asks to respawn.
+fn idles_out(idle_ticks: u64, minutes: i32, won_game: bool) -> bool {
+    let Ok(minutes @ 1..) = u64::try_from(minutes) else {
+        return false;
+    };
+    !won_game && idle_ticks > minutes * 1200
+}
+
 /// Log4j's console pattern: `[HH:mm:ss] [thread/LEVEL]: message`.
 pub(super) fn log(level: &str, message: &str) {
     log_from("Server thread", level, message);
@@ -528,6 +539,28 @@ fn parse_whitelist_bypass(text: &str) -> std::result::Result<Vec<String>, String
     Ok(out)
 }
 impl Lists {
+    /// The console's `/ban` of one player (`BanPlayerCommands.banPlayers`): whether they are banned now.
+    /// One banned already (`isBanned`) is left as they are, their first reason kept.
+    fn ban(&mut self, user: &NameAndId, reason: Option<String>) -> bool {
+        !self.bans.contains(user)
+            && self.bans.add(BanEntry::new(
+                user.clone(),
+                Some("Server".into()),
+                None,
+                reason,
+            ))
+    }
+
+    /// The console's `/ban-ip` (`BanIpCommands.banIp`): whether the address is banned now. One banned
+    /// already (`isBanned`) is left as it is.
+    fn ban_ip(&mut self, ip: &str, reason: Option<String>) -> bool {
+        let ip = ip.to_owned();
+        !self.ip_bans.contains(&ip)
+            && self
+                .ip_bans
+                .add(BanEntry::new(ip, Some("Server".into()), None, reason))
+    }
+
     fn load() -> Self {
         let mut l = Self {
             ops: OpList::new("ops.json"),
@@ -864,6 +897,28 @@ fn auto_save(state: &ServerState) -> bool {
     state.lists.lock().unwrap().autosave
 }
 
+/// `MinecraftServer.tickServer`'s pause-when-empty count. `pause_after` is its
+/// `pauseWhenEmptySeconds() * 20`; while that is above 0, a tick with no player and no
+/// `/tick sprint` running (`ServerTickRateManager.isSprinting`) adds one to `empty_ticks`, and any
+/// other tick sets it back to 0. A `/pregen` task keeps the server busy as a player would: paused,
+/// nothing would post-process its chunks. Returns whether the server is paused this tick.
+fn count_empty_tick(
+    empty_ticks: &mut i32,
+    pause_after: i32,
+    players: usize,
+    pregen: bool,
+    sprinting: bool,
+) -> bool {
+    if pause_after > 0 {
+        if players == 0 && !pregen && !sprinting {
+            *empty_ticks += 1;
+        } else {
+            *empty_ticks = 0;
+        }
+    }
+    pause_after > 0 && *empty_ticks >= pause_after
+}
+
 /// `MinecraftServer.setAutoSave`: enable or disable periodic saves and report whether it changed.
 pub(super) fn set_auto_save(lists: &Mutex<Lists>, enabled: bool) -> bool {
     let mut l = lists.lock().unwrap();
@@ -1048,9 +1103,17 @@ impl Game<'_> {
         // now rather than at the first tick (reading parses functions; it runs none), and a broken
         // predicate graph stops the start before anything listens (a partial check: predicate_graph.rs).
         self.ensure_datapacks();
-        if let Err(error) = predicate_graph::check(&self.fns.store.predicates) {
+        let store = &self.fns.store;
+        let tag = |id: &str| {
+            let (ns, path) = id.split_once(':').unwrap_or(("minecraft", id));
+            store
+                .files
+                .contains_key(&format!("tags/{ns}:predicate/{path}"))
+        };
+        if let Err(error) = predicate_graph::check(&store.predicates, tag) {
             let level = match error {
-                predicate_graph::GraphError::Unbound(_) => "ERROR",
+                predicate_graph::GraphError::Unbound(_)
+                | predicate_graph::GraphError::UnboundTags(_) => "ERROR",
                 predicate_graph::GraphError::Recursive(_) => "WARN",
             };
             for line in error.lines() {
@@ -1371,16 +1434,13 @@ impl Game<'_> {
             // Vanilla reads pauseWhenEmptySeconds on every tick, so management changes take effect
             // without restarting the server.
             let pause_after = state.pause_when_empty_seconds.wrapping_mul(20);
-            if pause_after > 0 {
-                // A `/pregen` task keeps the server busy as a player would:
-                // paused, nothing would post-process its chunks.
-                if players == 0 && self.pregen_level().is_none() {
-                    state.empty_ticks += 1;
-                } else {
-                    state.empty_ticks = 0;
-                }
-            }
-            let paused = pause_after > 0 && state.empty_ticks >= pause_after;
+            let paused = count_empty_tick(
+                &mut state.empty_ticks,
+                pause_after,
+                players,
+                self.pregen_level().is_some(),
+                self.clock.sprinting(),
+            );
             state.paused = paused;
             if paused && state.empty_ticks == pause_after {
                 log(
@@ -1578,12 +1638,15 @@ impl Game<'_> {
         let Some(host) = self.lan.as_mut() else {
             return;
         };
-        let limit = u64::try_from(minutes).unwrap_or(0) * 1200;
         let idle: Vec<u32> = host
             .hub
             .guests
             .iter()
-            .filter(|g| host.hub.ticks.saturating_sub(g.last_action_tick) > limit)
+            .filter(|g| {
+                let idle_ticks = host.hub.ticks.saturating_sub(g.last_action_tick);
+                let won_game = host.play.get(&g.conn).is_some_and(|play| play.won_game);
+                idles_out(idle_ticks, minutes, won_game)
+            })
             .map(|g| g.conn)
             .collect();
         for conn in idle {
@@ -1692,9 +1755,17 @@ impl Game<'_> {
     /// bound to the overworld, whichever level the last server tick left in
     /// place (the last one ticked, often the nether). Its commands run there
     /// and the level in place is put back afterwards.
+    /// The source is the server's own: no entity, at the world spawn, its feedback heard
+    /// (the console's and an RCON client's always is).
     fn as_console_in_overworld<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T {
         let back = console_level(self.dim).and_then(|dim| self.enter_command_level(dim));
+        let source = super::commands::execute::Source {
+            silent: false,
+            ..self.server_source()
+        };
+        let outer = self.command_source.replace(source);
         let out = self.as_console(f);
+        self.command_source = outer;
         if let Some(back) = back {
             self.enter_command_level(back);
         }
@@ -1912,12 +1983,7 @@ impl Game<'_> {
                     return;
                 };
                 let reason = (rest.len() > 1).then(|| rest[1..].join(" "));
-                let added = state.lists.lock().unwrap().bans.add(BanEntry::new(
-                    user.clone(),
-                    Some("Server".into()),
-                    None,
-                    reason.clone(),
-                ));
+                let added = state.lists.lock().unwrap().ban(&user, reason.clone());
                 if added {
                     self.console_reply(Text::translate(
                         "commands.ban.success",
@@ -1957,12 +2023,7 @@ impl Game<'_> {
                     return;
                 };
                 let reason = (rest.len() > 1).then(|| rest[1..].join(" "));
-                let added = state.lists.lock().unwrap().ip_bans.add(BanEntry::new(
-                    ip.clone(),
-                    Some("Server".into()),
-                    None,
-                    reason.clone(),
-                ));
+                let added = state.lists.lock().unwrap().ban_ip(&ip, reason.clone());
                 if !added {
                     self.console_reply(Text::translate("commands.banip.failed", &[]));
                     return;
@@ -2580,6 +2641,23 @@ mod tests {
         assert!(parse_whitelist_bypass("not-a-uuid-at-all").is_err());
     }
 
+    /// ServerGamePacketListenerImpl.tick: a player idle past `player-idle-timeout` minutes is kicked,
+    /// unless the End poem is showing (`ServerPlayer.wonGame`), which sends no action.
+    #[test]
+    fn a_player_watching_the_end_credits_is_not_kicked_for_idling() {
+        use super::idles_out;
+        // 5 minutes: 6000 ticks. One more is over the limit.
+        assert!(!idles_out(6000, 5, false));
+        assert!(idles_out(6001, 5, false));
+        assert!(!idles_out(6001, 5, true));
+        assert!(!idles_out(1_000_000, 5, true));
+        // The credits are over (won_game false again): the same idle time kicks.
+        assert!(idles_out(1_000_000, 5, false));
+        // 0 or less: no timeout.
+        assert!(!idles_out(1_000_000, 0, false));
+        assert!(!idles_out(1_000_000, -3, false));
+    }
+
     /// `SaveAllCommand.saveAll`: a save that throws is the `ERROR_FAILED` the
     /// source is told about, not a log line the caller never sees.
     #[test]
@@ -2604,6 +2682,51 @@ mod tests {
         );
     }
 
+    /// MinecraftServer.tickServer: a tick only counts toward pause-when-empty with no player and
+    /// no `/tick sprint` running (`ServerTickRateManager.isSprinting`); a sprint on an empty server
+    /// keeps the count at 0, so it is never paused, and the count starts again after it.
+    #[test]
+    fn a_sprint_on_an_empty_server_does_not_count_toward_the_pause() {
+        let pause_after = 60 * 20;
+        let mut empty_ticks = 0;
+        // One server tick: (players, a `/pregen` task, a `/tick sprint`) -> paused.
+        let tick = |empty_ticks: &mut i32, players, pregen, sprinting| {
+            super::count_empty_tick(empty_ticks, pause_after, players, pregen, sprinting)
+        };
+        for _ in 0..2000 {
+            assert!(!tick(&mut empty_ticks, 0, false, true));
+        }
+        assert_eq!(empty_ticks, 0);
+        // The sprint ended: 1200 empty ticks later the server pauses, not before.
+        for n in 1..=pause_after {
+            assert_eq!(
+                tick(&mut empty_ticks, 0, false, false),
+                n == pause_after,
+                "tick {n}"
+            );
+        }
+        // A sprint that starts while paused resumes the server at once.
+        assert!(!tick(&mut empty_ticks, 0, false, true));
+        assert_eq!(empty_ticks, 0);
+        // A player, or a `/pregen` task, resets the count too.
+        empty_ticks = 5;
+        assert!(!tick(&mut empty_ticks, 1, false, false));
+        assert_eq!(empty_ticks, 0);
+        empty_ticks = 5;
+        assert!(!tick(&mut empty_ticks, 0, true, false));
+        assert_eq!(empty_ticks, 0);
+        // pause-when-empty-seconds=0 never pauses and leaves the count alone.
+        empty_ticks = 5;
+        assert!(!super::count_empty_tick(
+            &mut empty_ticks,
+            0,
+            0,
+            false,
+            false
+        ));
+        assert_eq!(empty_ticks, 5);
+    }
+
     /// A `panic!("literal")` carries a `&str`, a formatted one a `String`; anything else is
     /// named as unknown, so the crash line is never empty.
     #[test]
@@ -2713,6 +2836,46 @@ mod tests {
         }
     }
 
+    /// `BanPlayerCommands.banPlayers` skips a player who `isBanned`, and `BanIpCommands.banIp` refuses an
+    /// address that is: the console's `/ban` and `/ban-ip` of one banned already change nothing (the first
+    /// reason stays, and the console hears "Nothing changed"), whatever reason they give.
+    #[test]
+    fn the_console_does_not_ban_again_who_is_banned_already() {
+        use super::{BanList, Lists, NameAndId};
+        let dir = std::env::temp_dir().join(format!("horizon-console-ban-{}", std::process::id()));
+        fs::create_dir_all(&dir).unwrap();
+        let mut lists = Lists {
+            ops: super::OpList::new(dir.join("ops.json")),
+            white: super::WhiteList::new(dir.join("whitelist.json")),
+            bans: BanList::new(dir.join("banned-players.json")),
+            ip_bans: super::IpBanList::new(dir.join("banned-ips.json")),
+            use_whitelist: false,
+            enforce_whitelist: false,
+            op_level: 4,
+            player_idle_timeout: 0,
+            stop: false,
+            autosave: true,
+            whitelist_bypass: Vec::new(),
+        };
+        let alpha = NameAndId {
+            id: 0x5ca1ab1e,
+            name: "Alpha".into(),
+        };
+        assert!(lists.ban(&alpha, Some("cheating".into())));
+        assert!(!lists.ban(&alpha, Some("again".into())));
+        assert!(!lists.ban(&alpha, None));
+        let reason = lists.bans.get(&alpha).and_then(|b| b.reason.clone());
+        assert_eq!(reason.as_deref(), Some("cheating"));
+        assert!(lists.ban_ip("1.2.3.4", Some("spam".into())));
+        assert!(!lists.ban_ip("1.2.3.4", Some("more spam".into())));
+        let reason = lists
+            .ip_bans
+            .get(&"1.2.3.4".to_owned())
+            .and_then(|b| b.reason.clone());
+        assert_eq!(reason.as_deref(), Some("spam"));
+        let _ = fs::remove_dir_all(&dir);
+    }
+
     /// A temporary ban (`/tempban`, the chat filter's) keeps the player out and says when it ends;
     /// once it has ended, or after `/pardon`, they come in.
     #[test]
@@ -2796,3 +2959,85 @@ mod tests {
         fs::remove_dir_all(dir).unwrap();
     }
 }
+
+#[cfg(test)]
+mod console_source_tests {
+    use crate::game::{Audio, Game, Options, Progress, Settings, load_resources};
+    use horizon_client::chunk::Chunk;
+    use horizon_core::position::ChunkPos;
+    use std::sync::Arc;
+
+    /// Runs `command` as the console does and returns whether it worked and every message it printed.
+    fn console(game: &mut Game<'_>, command: &str) -> (bool, String) {
+        game.chat_capture = Some(Vec::new());
+        let ok = game.as_console_in_overworld(|g| g.run_command(command));
+        let said = game.chat_capture.take().unwrap_or_default();
+        let said = said
+            .iter()
+            .map(|t| t.component().to_string())
+            .collect::<Vec<_>>()
+            .join("\n");
+        (ok, said)
+    }
+
+    /// `MinecraftServer.createCommandSourceStack`: the console's source has no entity and is named "Server"
+    /// (an RCON client's, `RconConsoleSource`, "Rcon"): `/me` says so, and `teammsg`, which needs an entity,
+    /// refuses it (`permissions.requires.entity`) instead of running as the player in place.
+    #[test]
+    #[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES and scratch homes/cwd"]
+    fn the_console_runs_as_the_server_not_the_player_in_place() {
+        let root = std::path::PathBuf::from(
+            std::env::var_os("HORIZON_TEST_RESOURCES").expect("prepared resources required"),
+        );
+        let settings = Settings::default();
+        let loaded = load_resources(
+            root.clone(),
+            None,
+            &root,
+            &settings,
+            std::time::Instant::now(),
+            false,
+            true,
+            &Progress::new(),
+            &mut |_, _| unreachable!(),
+        )
+        .unwrap();
+        let mut options = Options::parse(std::iter::empty()).unwrap().unwrap();
+        options.resources = root.clone();
+        options.execution_role = crate::game::execution_role::ExecutionRole::IntegratedServer;
+        let mut game = Game::new(
+            &loaded.resources,
+            loaded.pack,
+            loaded.gui.unwrap(),
+            options,
+            settings,
+            Audio::silent(&root),
+            None,
+        )
+        .unwrap();
+        game.build_registries();
+        game.set_allow_commands(true);
+        game.world
+            .chunks
+            .insert((0, 0), Arc::new(Chunk::empty(0, 0)));
+        game.block_ticks
+            .add_empty_chunk(ChunkPos::new(0, 0))
+            .unwrap();
+        let (ok, said) = console(&mut game, "me waves");
+        assert!(
+            ok && said.contains("chat.type.emote") && said.contains("\"Server\""),
+            "{said}"
+        );
+        game.rcon_source = true;
+        let (ok, said) = console(&mut game, "me waves");
+        assert!(ok && said.contains("\"Rcon\""), "{said}");
+        game.rcon_source = false;
+        let (ok, said) = console(&mut game, "teammsg hi");
+        assert!(
+            !ok && said.contains("permissions.requires.entity"),
+            "{said}"
+        );
+        // The console's source is put back after each line.
+        assert!(game.command_source.is_none());
+    }
+}

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

@@ -1,13 +1,16 @@
 //! A partial check of the world's predicate graph before a dedicated server is Ready.
 //!
 //! Vanilla refuses to start a world whose packs' predicates reference a predicate no pack defines
-//! (`MappedRegistry.freeze`: "Unbound values in registry"), or reference each other in a cycle
+//! (`MappedRegistry.freeze`: "Unbound values in registry"), name a predicate tag no pack defines
+//! ("Unbound tags in registry"), or reference each other in a cycle
 //! (`ReloadableServerRegistries.validateLootRegistries`: a reference "is recursively called").
 //!
 //! This is new, partial validation, not a port of `RegistryDataLoader` or `ValidationContext`. It
 //! follows a predicate's holders only where the condition codecs hold one: `all_of` and `any_of`
 //! `terms`, and `inverted` `term`. A holder is an identifier (a reference) or an inline condition,
-//! which is followed in the same way. Every other condition type and field, an identifier that does
+//! which is followed in the same way. `terms` is a `HolderSetCodec`: a list of holders, one holder
+//! alone (`compactListCodec`, at `.terms[0]`), or a `#tag`. A tag must be defined; the entries of a
+//! defined tag are not followed. Every other condition type and field, an identifier that does
 //! not parse, and the holders of loot tables, advancements and item modifiers are not checked.
 use horizon_client_core::identifier::parse_identifier;
 use serde_json::Value;
@@ -20,6 +23,8 @@ const REGISTRY: &str = "minecraft:predicate";
 pub(super) enum GraphError {
     /// Referenced ids that no predicate binds.
     Unbound(BTreeSet<String>),
+    /// Predicate tags that a `terms` names and no pack defines.
+    UnboundTags(BTreeSet<String>),
     /// References that re-enter a predicate while it is being validated.
     Recursive(Vec<Recursion>),
 }
@@ -39,6 +44,10 @@ impl GraphError {
                 "Unbound values in registry ResourceKey[minecraft:root / {REGISTRY}]: [{}]",
                 ids.iter().cloned().collect::<Vec<_>>().join(", ")
             )],
+            GraphError::UnboundTags(ids) => vec![format!(
+                "Unbound tags in registry ResourceKey[minecraft:root / {REGISTRY}]: [{}]",
+                ids.iter().cloned().collect::<Vec<_>>().join(", ")
+            )],
             GraphError::Recursive(found) => found
                 .iter()
                 .map(|r| {
@@ -62,14 +71,16 @@ fn holders(condition: &Value) -> Vec<(String, &Value)> {
         return Vec::new();
     };
     match ty.as_str() {
-        "minecraft:all_of" | "minecraft:any_of" => condition
-            .get("terms")
-            .and_then(Value::as_array)
-            .into_iter()
-            .flatten()
-            .enumerate()
-            .map(|(i, term)| (format!(".terms[{i}]"), term))
-            .collect(),
+        "minecraft:all_of" | "minecraft:any_of" => match condition.get("terms") {
+            Some(Value::Array(terms)) => terms
+                .iter()
+                .enumerate()
+                .map(|(i, term)| (format!(".terms[{i}]"), term))
+                .collect(),
+            Some(Value::String(tag)) if tag.starts_with('#') => Vec::new(),
+            Some(term) => vec![(".terms[0]".to_owned(), term)],
+            None => Vec::new(),
+        },
         "minecraft:inverted" => condition
             .get("term")
             .map(|term| vec![(".term".to_owned(), term)])
@@ -78,12 +89,22 @@ fn holders(condition: &Value) -> Vec<(String, &Value)> {
     }
 }
 
-/// Every reference a condition holds, inline conditions included.
-fn references(condition: &Value, out: &mut Vec<String>) {
+/// The predicate tag an `all_of` or `any_of` names as its `terms` (`#ns:path`).
+fn tag(condition: &Value) -> Option<String> {
+    let ty = parse_identifier(condition.get("type")?.as_str()?)?;
+    if !matches!(ty.as_str(), "minecraft:all_of" | "minecraft:any_of") {
+        return None;
+    }
+    parse_identifier(condition.get("terms")?.as_str()?.strip_prefix('#')?)
+}
+
+/// Every reference and tag a condition holds, inline conditions included.
+fn references(condition: &Value, out: &mut Vec<String>, tags: &mut Vec<String>) {
+    tags.extend(tag(condition));
     for (_, holder) in holders(condition) {
         match holder {
             Value::String(name) => out.extend(parse_identifier(name)),
-            Value::Object(_) => references(holder, out),
+            Value::Object(_) => references(holder, out, tags),
             _ => {}
         }
     }
@@ -125,12 +146,17 @@ fn walk<'v>(
     }
 }
 
-/// The world's predicates (by normalized id, after pack precedence): missing references first, as
-/// the registry freezes before anything is validated, then recursive ones.
-pub(super) fn check(predicates: &BTreeMap<String, Value>) -> Result<(), GraphError> {
+/// The world's predicates (by normalized id, after pack precedence) and whether a pack defines a
+/// predicate tag: missing references first, then missing tags, as the registry freezes before
+/// anything is validated, then recursive references.
+pub(super) fn check(
+    predicates: &BTreeMap<String, Value>,
+    has_tag: impl Fn(&str) -> bool,
+) -> Result<(), GraphError> {
     let mut referenced = Vec::new();
+    let mut tags = Vec::new();
     for condition in predicates.values() {
-        references(condition, &mut referenced);
+        references(condition, &mut referenced, &mut tags);
     }
     let unbound: BTreeSet<String> = referenced
         .into_iter()
@@ -139,6 +165,10 @@ pub(super) fn check(predicates: &BTreeMap<String, Value>) -> Result<(), GraphErr
     if !unbound.is_empty() {
         return Err(GraphError::Unbound(unbound));
     }
+    let unbound: BTreeSet<String> = tags.into_iter().filter(|id| !has_tag(id)).collect();
+    if !unbound.is_empty() {
+        return Err(GraphError::UnboundTags(unbound));
+    }
     let mut found = Vec::new();
     for (id, condition) in predicates {
         let mut stack = vec![id.as_str()];
@@ -193,7 +223,7 @@ mod tests {
             // An identifier that does not parse is not checked here.
             ("a:v", json!({"type": "inverted", "term": "Not An Id"})),
         ]);
-        assert_eq!(check(&predicates), Ok(()));
+        assert_eq!(check(&predicates, |_| false), Ok(()));
     }
 
     #[test]
@@ -205,7 +235,7 @@ mod tests {
             ),
             ("a:c", json!({"type": "inverted", "term": "a:c"})),
         ]);
-        let error = check(&predicates).unwrap_err();
+        let error = check(&predicates, |_| false).unwrap_err();
         assert_eq!(
             error,
             GraphError::Unbound(["a:gone".to_owned(), "b:none".to_owned()].into())
@@ -234,7 +264,7 @@ mod tests {
                 json!({"type": "any_of", "terms": [{"type": "inverted", "term": "prg:self"}]}),
             ),
         ]);
-        let mut lines = check(&predicates).unwrap_err().lines();
+        let mut lines = check(&predicates, |_| false).unwrap_err().lines();
         lines.sort();
         // The two cycle lines are the ones vanilla 26.3 logged for this pack.
         assert_eq!(
@@ -246,4 +276,74 @@ mod tests {
             ]
         );
     }
+
+    #[test]
+    fn a_lone_terms_holder_is_terms_0_and_a_tag_must_be_defined() {
+        let target = json!({"type": "minecraft:all_of", "terms": []});
+        // Vanilla 26.3 starts a world whose `terms` is one bound holder alone.
+        let valid = graph(&[
+            ("prg:target", target.clone()),
+            ("prg:ref", json!({"type": "all_of", "terms": "prg:target"})),
+            (
+                "prg:inline",
+                json!({"type": "any_of", "terms": {"type": "inverted", "term": "prg:target"}}),
+            ),
+            (
+                "prg:tagged",
+                json!({"type": "any_of", "terms": "#prg:some"}),
+            ),
+        ]);
+        assert_eq!(check(&valid, |tag| tag == "prg:some"), Ok(()));
+        let missing = graph(&[
+            ("prg:target", target.clone()),
+            (
+                "prg:ref",
+                json!({"type": "minecraft:all_of", "terms": "prg:missing"}),
+            ),
+            (
+                "prg:tagged",
+                json!({"type": "all_of", "terms": "#prg:none"}),
+            ),
+        ]);
+        // Missing values first, then missing tags: the lines vanilla 26.3 logged for each.
+        assert_eq!(
+            check(&missing, |_| false).unwrap_err().lines(),
+            [
+                "Unbound values in registry ResourceKey[minecraft:root / minecraft:predicate]: [prg:missing]"
+            ]
+        );
+        let tags = graph(&[
+            ("prg:target", target.clone()),
+            (
+                "prg:ref",
+                json!({"type": "minecraft:all_of", "terms": "#prg:none"}),
+            ),
+        ]);
+        assert_eq!(
+            check(&tags, |_| false).unwrap_err().lines(),
+            [
+                "Unbound tags in registry ResourceKey[minecraft:root / minecraft:predicate]: [prg:none]"
+            ]
+        );
+        let cycle = graph(&[
+            ("prg:target", target),
+            (
+                "prg:ref",
+                json!({"type": "minecraft:any_of", "terms": "prg:loop"}),
+            ),
+            (
+                "prg:loop",
+                json!({"type": "minecraft:inverted", "term": "prg:ref"}),
+            ),
+        ]);
+        let mut lines = check(&cycle, |_| false).unwrap_err().lines();
+        lines.sort();
+        assert_eq!(
+            lines,
+            [
+                "Found loot table element validation problem in {prg:loop@minecraft:predicate}.term->{prg:ref@minecraft:predicate}.terms[0]: prg:loop of type minecraft:predicate is recursively called",
+                "Found loot table element validation problem in {prg:ref@minecraft:predicate}.terms[0]->{prg:loop@minecraft:predicate}.term: prg:ref of type minecraft:predicate is recursively called",
+            ]
+        );
+    }
 }

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

@@ -982,6 +982,7 @@ impl Game<'_> {
                         items: [stack],
                         ticks: 0,
                         playing: false,
+                        loaded_clock: false,
                     }),
                 );
             }
@@ -1442,6 +1443,9 @@ impl Game<'_> {
                 ProjectileKind::Egg => "minecraft:egg",
                 ProjectileKind::SmallFireball => "minecraft:small_fireball",
                 ProjectileKind::WindCharge => "minecraft:wind_charge",
+                ProjectileKind::Potion(_, true) => "minecraft:lingering_potion",
+                ProjectileKind::Potion(..) => "minecraft:splash_potion",
+                ProjectileKind::ExperienceBottle => "minecraft:experience_bottle",
                 _ => "minecraft:unknown_projectile",
             };
             let (p, v) = (shot.position, shot.velocity);

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

@@ -12,7 +12,6 @@ use horizon_client::{
     mobs::{Mob, Species, sulfur_cube},
     particles::{ParticleOptions, ParticleType},
     projectiles::{Projectile, ProjectileKind},
-    random_source,
 };
 // Its old home, for mixin code that names it here.
 pub(super) use horizon_client::mod_api::NativeDispensed;
@@ -1198,9 +1197,9 @@ impl Game<'_> {
             "minecraft:experience_bottle"
             | "minecraft:splash_potion"
             | "minecraft:lingering_potion" => {
-                let mut shot = Projectile::new(ProjectileKind::Snowball, at, None);
-                shot.shoot(&mut random_source::entity(), dir, power, uncertainty);
-                self.launch_thrown(one, at, shot.velocity, None);
+                let mut shot = super::potions::thrown_projectile(one, at, false);
+                shot.shoot_own(dir, power, uncertainty);
+                self.add_projectile(shot);
             }
             _ => {
                 let kind = match item.as_str() {
@@ -1267,14 +1266,18 @@ impl Game<'_> {
         self.next_entity += 1;
         let (_, uuid) = horizon_client::mobs::living_random();
         self.persist.uuids.insert(self.next_entity, uuid);
-        let mut stand =
+        let stand =
             horizon_client::entities::ArmorStand::new(self.next_entity, foot, y_rot(facing));
-        // Entity.applyImplicitComponents: a name from an anvil names the stand.
-        if let Some(name) = stack.custom_name() {
-            stand.custom_name = Some(horizon_client::text::Text::literal(name));
-        }
         self.world.modified.insert((front.0 >> 4, front.2 >> 4));
         self.armor_stands.push(stand);
+        // EntityType.appendDefaultStackConfig: the dispenser's yaw first, then
+        // the item's createDefaultStackConfig with no user.
+        self.apply_item_stack_config(
+            super::commands::Target::Stand(self.next_entity),
+            "minecraft:armor_stand",
+            &stack,
+            false,
+        );
         (shrink(stack), CLICK)
     }
     /// A tame donkey, mule or llama in front without a chest gets it.
@@ -1343,7 +1346,7 @@ impl Game<'_> {
         self.boats.push(boat);
         // BoatDispenseItemBehavior: createDefaultStackConfig with no user,
         // then setYRot(direction.toYRot()).
-        self.apply_vehicle_stack_config(super::commands::Target::Boat(id), &kind, &stack, false);
+        self.apply_item_stack_config(super::commands::Target::Boat(id), &kind, &stack, false);
         self.set_boat_yaw(id, yaw);
         if self.serving.is_some() || self.options.dedicated.is_some() {
             let boat = self.boats.last().unwrap();
@@ -1393,12 +1396,7 @@ impl Game<'_> {
         self.carts.push(cart);
         // AbstractMinecart.createMinecart: createDefaultStackConfig with no user.
         let id = self.next_entity;
-        self.apply_vehicle_stack_config(
-            super::commands::Target::Cart(id),
-            kind.id(),
-            &stack,
-            false,
-        );
+        self.apply_item_stack_config(super::commands::Target::Cart(id), kind.id(), &stack, false);
         if self.serving.is_some() || self.options.dedicated.is_some() {
             let cart = self.carts.last().unwrap();
             self.native_vehicle_create(

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

@@ -191,22 +191,12 @@ pub(super) struct Crystal {
     pub beam: Option<[i32; 3]>,
     /// `setPermanentlyInvulnerable` (respawned spike crystals).
     pub invulnerable: bool,
+    /// `onGround` and `fallDistance`: a crystal never moves itself, so they stay
+    /// as loaded until `/tp` grounds it or a cobweb or powder snow resets the
+    /// fall (`crystal.rs`).
+    pub fall: (bool, f64),
 }
 impl Crystal {
-    /// The start of `time` (the spin and bob) for a crystal at `position`: the random draw
-    /// vanilla makes, or under `HORIZON_STILL` one seeded from the position alone. Which crystal
-    /// gets which draw, and a server's entity ids, follow the order chunks load in, which differs
-    /// between launches; the position is the same in every copy of the world. The draw is made
-    /// either way, so the random stays where it would be.
-    pub(super) fn start_time(position: Vec3, drawn: i32, still: bool) -> i32 {
-        if still {
-            horizon_client::mobs::entity_random(0, position)
-                .next_int_bound(100_000)
-                .unwrap_or(0)
-        } else {
-            drawn
-        }
-    }
     /// `EntityType.END_CRYSTAL`: 2 x 2.
     pub(super) fn bounds(&self) -> Aabb {
         let p = self.position;
@@ -1291,14 +1281,8 @@ impl Game<'_> {
             let time = Crystal::start_time(at, drawn, self.clock.still());
             // EndCrystal's constructor takes an id from the entity counter.
             self.next_entity += 1;
-            self.crystals.push(Crystal {
-                id: self.next_entity,
-                position: at,
-                show_bottom: true,
-                time,
-                beam: None,
-                invulnerable: false,
-            });
+            self.crystals
+                .push(Crystal::new(self.next_entity, at, true, time));
             self.world
                 .modified
                 .insert((at.x.floor() as i32 >> 4, at.z.floor() as i32 >> 4));
@@ -1328,6 +1312,7 @@ impl Game<'_> {
             .flatten();
         for i in 0..self.crystals.len() {
             self.crystals[i].time += 1;
+            self.crystal_block_effects(i);
             let p = self.crystals[i].position;
             let b = [p.x.floor() as i32, p.y.floor() as i32, p.z.floor() as i32];
             if let Some(fire) = fire
@@ -3666,7 +3651,7 @@ impl Crystal {
             self.position,
             Vec3::ZERO,
             [0.0, 0.0],
-            (false, 0.0),
+            self.fall,
             uuid,
             raw,
         );
@@ -3694,6 +3679,7 @@ impl Crystal {
                 _ => None,
             },
             invulnerable: horizon_client::entity_nbt::flag(tag, "Invulnerable"),
+            fall: horizon_client::entity_nbt::ground_from_nbt(tag),
         })
     }
 }
@@ -3916,14 +3902,8 @@ impl Game<'_> {
         // EndCrystal's constructor takes an id from the entity counter, so
         // the crystal is an entity a command can name (`@e[type=end_crystal]`).
         self.next_entity += 1;
-        self.crystals.push(Crystal {
-            id: self.next_entity,
-            position: at,
-            show_bottom: false,
-            time,
-            beam: None,
-            invulnerable: false,
-        });
+        self.crystals
+            .push(Crystal::new(self.next_entity, at, false, time));
         // EndCrystalItem.useOn: ENTITY_PLACE at the block above, by the player.
         self.post_block_game_event("minecraft:entity_place", above, self.sculk_actor(), None);
         self.world.modified.insert((above[0] >> 4, above[2] >> 4));
@@ -4219,12 +4199,9 @@ impl Game<'_> {
         let drawn = self.world.random.next_int_bound(100_000).unwrap_or(0);
         let time = Crystal::start_time(at, drawn, self.clock.still());
         self.crystals.push(Crystal {
-            id: 0,
-            position: at,
-            show_bottom: true,
-            time,
             beam: Some([0, 128, 0]),
             invulnerable: true,
+            ..Crystal::new(0, at, true, time)
         });
         let _ = self.set_state_named([cx, h, cz], "minecraft:bedrock", &[]);
         let _ = self.set_state_named([cx, h + 1, cz], "minecraft:fire", &[]);
@@ -4769,6 +4746,7 @@ impl Game<'_> {
     }
 }
 
+mod crystal;
 mod death_render;
 use death_render::{dissolve_color, dissolve_mask, dragon_rays};
 
@@ -5733,6 +5711,7 @@ mod dragon_fireball_spawn_tests {
                     .insert((x, z), Arc::new(Chunk::empty(x, z)));
             }
         }
+        game.load_ticking_neighbourhood(0, 0);
         assert!(game.run_command("forceload add 0 0"));
         game
     }

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

@@ -0,0 +1,60 @@
+//! An end crystal's construction and the blocks its tick reads.
+use super::*;
+
+impl Crystal {
+    /// `new EndCrystal(level, x, y, z)`: no beam, not invulnerable, on no
+    /// ground with no fall (what `Entity`'s constructor leaves).
+    pub(in crate::game) fn new(id: u32, position: Vec3, show_bottom: bool, time: i32) -> Self {
+        Self {
+            id,
+            position,
+            show_bottom,
+            time,
+            beam: None,
+            invulnerable: false,
+            fall: (false, 0.0),
+        }
+    }
+    /// The start of `time` (the spin and bob) for a crystal at `position`: the random draw
+    /// vanilla makes, or under `HORIZON_STILL` one seeded from the position alone. Which crystal
+    /// gets which draw, and a server's entity ids, follow the order chunks load in, which differs
+    /// between launches; the position is the same in every copy of the world. The draw is made
+    /// either way, so the random stays where it would be.
+    pub(in crate::game) fn start_time(position: Vec3, drawn: i32, still: bool) -> i32 {
+        if still {
+            horizon_client::mobs::entity_random(0, position)
+                .next_int_bound(100_000)
+                .unwrap_or(0)
+        } else {
+            drawn
+        }
+    }
+}
+
+impl Game<'_> {
+    /// `EndCrystal.tick`'s `applyEffectsFromBlocks` for crystal `i`, which never
+    /// moves: a cobweb or powder snow in its box (2 x 2 x 2, deflated by
+    /// `1.0E-5F`) calls `makeStuckInBlock`, which resets its fall distance.
+    /// Powder snow's inside shape for a fall over 2.5 is only 0.9 tall
+    /// (`FALLING_COLLISION_SHAPE`). A bubble column's reset and `stepOn` for a
+    /// grounded crystal are not ported.
+    pub(super) fn crystal_block_effects(&mut self, i: usize) {
+        let (p, fall) = (self.crystals[i].position, self.crystals[i].fall.1);
+        let e = f64::from(1.0e-5_f32);
+        let lo = [p.x - 1.0 + e, p.y + e, p.z - 1.0 + e].map(|v| v.floor() as i32);
+        let hi = [p.x + 1.0 - e, p.y + 2.0 - e, p.z + 1.0 - e].map(|v| v.floor() as i32);
+        let facts = self.res.facts();
+        let stuck = (lo[0]..=hi[0]).any(|x| {
+            (lo[1]..=hi[1]).any(|y| {
+                (lo[2]..=hi[2]).any(|z| match &*facts.get(self.world.block(x, y, z)).name {
+                    "minecraft:cobweb" => true,
+                    "minecraft:powder_snow" => fall <= 2.5 || p.y + e < f64::from(y) + 0.9,
+                    _ => false,
+                })
+            })
+        });
+        if stuck {
+            self.crystals[i].fall.1 = 0.0;
+        }
+    }
+}

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

@@ -47,6 +47,7 @@ fn game() -> Game<'static> {
     game.block_ticks
         .add_empty_chunk(ChunkPos::new(0, 0))
         .unwrap();
+    game.load_ticking_neighbourhood(0, 0);
     assert!(game.run_command("fill 0 99 0 15 99 15 stone"));
     game
 }

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

@@ -68,6 +68,7 @@ fn items_past_the_simulation_distance_enter_no_end_gateway() {
         game.world
             .chunks
             .insert((cx, 0), Arc::new(Chunk::empty(cx, 0)));
+        game.load_ticking_neighbourhood(cx, 0);
         game.world.set(x, 64, 8, gateway).unwrap();
         game.dropped
             .push(item(id, Vec3::new(f64::from(x) + 0.5, 64.2, 8.5)));

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

@@ -36,6 +36,7 @@ fn a_mob_presses_a_plate_only_inside_the_simulation_distance() {
         game.world
             .chunks
             .insert((cx, 0), Arc::new(Chunk::empty(cx, 0)));
+        game.load_ticking_neighbourhood(cx, 0);
         game.world.set(x, 63, 8, stone).unwrap();
         game.world.set(x, 64, 8, plate).unwrap();
         game.mobs.push(Mob::new(

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

@@ -862,13 +862,36 @@ impl Game<'_> {
         let (mut items_kept, mut orbs_kept) = (0, 0);
         let (mut boats_gone, mut carts_gone) = (0, 0);
         let mut destroyed_contents = Vec::new();
+        // The entities in reach, less those a mod spares (`native_explosion_entities`); no list
+        // without native mods, which are the only ones to spare any.
+        let spared: std::collections::HashSet<u32> = if horizon_client::mod_api::mods().is_empty() {
+            Default::default()
+        } else {
+            let reach: Vec<u32> = self
+                .entity_handles()
+                .filter_map(|handle| {
+                    with_entity!(self, handle, e => {
+                        let feet = e.position();
+                        let dist = blast_distance(center, [feet.x, feet.y, feet.z]);
+                        (dist <= diameter).then(|| e.id())
+                    })
+                })
+                .collect();
+            let mut kept = reach.clone();
+            self.native_explosion_entities(self.dim.id(), center, &mut kept);
+            let kept: std::collections::HashSet<u32> = kept.into_iter().collect();
+            reach.into_iter().filter(|id| !kept.contains(id)).collect()
+        };
         for handle in self.entity_handles() {
             let handle = match handle {
                 EntityHandle::Boat(i) => EntityHandle::Boat(i - boats_gone),
                 EntityHandle::Cart(i) => EntityHandle::Cart(i - carts_gone),
                 other => other,
             };
-            let hit = with_entity!(self, handle, e => self.blast_hit(e, center, diameter, &blast));
+            let spare =
+                !spared.is_empty() && spared.contains(&with_entity!(self, handle, e => e.id()));
+            let hit = with_entity!(self, handle, e => self.blast_hit(e, center, diameter, &blast))
+                .filter(|_| !spare);
             let mut destroyed = false;
             if let Some(Hit {
                 dist,
@@ -1828,6 +1851,55 @@ mod tests {
         })
     }
 
+    /// Spares one entity from every blast (`native_explosion_entities`).
+    struct Spare(u32);
+    impl crate::mod_api::Hooks for Spare {
+        fn explosion_entities(
+            &self,
+            _: &mut dyn crate::mod_api::Host,
+            event: &mut crate::mod_api::ExplosionEntitiesEvent<'_>,
+        ) {
+            event.entities.retain(|&id| id != self.0);
+        }
+    }
+
+    #[test]
+    #[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
+    fn a_mod_spares_an_entity_from_a_blast() {
+        crate::mod_api::in_own_process(
+            "game::explosion::tests::a_mod_spares_an_entity_from_a_blast",
+            a_mod_spares_an_entity_from_a_blast_in_own_process,
+        );
+    }
+
+    /// Two husks either side of a blast: the one a mod takes out of the list is neither hurt nor
+    /// pushed, the other is both.
+    fn a_mod_spares_an_entity_from_a_blast_in_own_process() {
+        let mut game = crate::game::native_machines::tests::server_game();
+        game.build_registries();
+        let spare: Box<dyn crate::mod_api::Hooks> = Box::new(Spare(2));
+        assert!(crate::mod_api::MODS.set(vec![spare].into()).is_ok());
+        let kind = game.res.mob_types().get("minecraft:husk").unwrap().clone();
+        for (id, x) in [(1, 6.5), (2, 10.5)] {
+            let husk =
+                horizon_client::mobs::Mob::new(id, kind.clone(), Vec3::new(x, 64.0, 8.5), 0.0);
+            game.mobs.push(husk);
+        }
+        let full = game.mobs[0].health;
+        game.server_explode_from_cause(
+            [8.5, 64.0, 8.5],
+            2.0,
+            BlockInteraction::Keep,
+            false,
+            ExplosionSource::default().with_silence(true),
+            None,
+        )
+        .unwrap();
+        let (hit, spared) = (&game.mobs[0], &game.mobs[1]);
+        assert!(hit.health < full && hit.velocity != Vec3::ZERO);
+        assert_eq!((spared.health, spared.velocity), (full, Vec3::ZERO));
+    }
+
     #[test]
     fn a_mob_that_refuses_the_hit_is_still_pushed() {
         use horizon_client::mobs::{Damage, DamageKind, Mob, Species};

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

@@ -4,9 +4,12 @@
 //! Each hook does nothing while its extra is off and no mod uses it.
 //!
 //! Each Horizon extra's game glue is a child module here, so it leaves the engine in one move
-//! (docs/layers.md, plan M5): `reconnect` (auto-reconnect), `pvp` (the PvP & HUD options).
+//! (docs/layers.md, plan M5): `reconnect` (auto-reconnect), `pvp` (the PvP & HUD options),
+//! `mouse_tweaks` and `sorting` (the inventory extras).
+pub(in crate::game) mod mouse_tweaks;
 pub(in crate::game) mod pvp;
 mod reconnect;
+mod sorting;
 
 use super::{Dim, Game, Screen, native_hooks::NativeMinimap};
 use horizon_client::{

crates/horizon-client/src/game/extras/mouse_tweaks.rs

@@ -17,26 +17,12 @@
 //!   other side. Down over a result slot takes one craft or the whole furnace
 //!   output to the inventory; nothing ever goes into a result slot.
 //!
-//! Sorting draws a small button by a menu's storage slots and one by the
-//! inventory's (an optional key sorts the part under the cursor); the
-//! clicks come from `inv_sort::plan`.
-use super::{Creative, Game, Screen};
-use horizon_client::{
-    containers::BlockEntity,
-    hud::{HudBatch, rgba},
-    inv_sort,
-    items::ItemStack,
-    keybinds,
-    menu::Input,
-    stations::hover_name,
-};
-use winit::{event::MouseButton, keyboard::KeyCode};
-
-/// A sort button's side in GUI pixels.
-const SORT_BUTTON: f32 = 9.0;
+//! Sorting, which clicks through `tweak_click` too, is in `sorting.rs`.
+use crate::game::{Creative, Game, Screen};
+use horizon_client::{containers::BlockEntity, items::ItemStack, menu::Input};
 
 #[derive(Default)]
-pub(super) struct Tweaks {
+pub(in crate::game) struct Tweaks {
     drag: Option<Drag>,
     /// Wheel steps not yet acted on (a trackpad scrolls in fractions).
     wheel: f32,
@@ -44,7 +30,7 @@ pub(super) struct Tweaks {
 /// A server's menu the tweaks run in: their clicks are vanilla's in these,
 /// and the menu engine knows which slot takes what. Not the menus whose slots
 /// cost or trigger something (anvils, enchanting, merchants, beacons, crafters).
-pub(super) fn tweak_menu(name: &str) -> bool {
+pub(in crate::game) fn tweak_menu(name: &str) -> bool {
     name == "inventory"
         || name.starts_with("minecraft:generic_9x")
         || matches!(
@@ -72,7 +58,7 @@ struct Drag {
 
 impl Game<'_> {
     /// The open screen is one the tweaks run in, with the extra on.
-    pub(super) fn tweaks_on(&self) -> bool {
+    pub(in crate::game) fn tweaks_on(&self) -> bool {
         if !self.settings.extras.mouse_tweaks
             || self.screen != Screen::Inventory
             || self.station.is_some()
@@ -87,7 +73,7 @@ impl Game<'_> {
         }
     }
     /// One ordinary click on a game slot. False when nothing took it.
-    pub(super) fn tweak_click(&mut self, slot: usize, button: i32, input: Input) -> bool {
+    pub(in crate::game) fn tweak_click(&mut self, slot: usize, button: i32, input: Input) -> bool {
         if self.remote.is_some() {
             return self.remote_menu_ops(&[(Some(slot), button, input)]);
         }
@@ -123,7 +109,12 @@ impl Game<'_> {
     }
     /// A press on `slot`: true when the tweaks took it (a right-drag
     /// placing), else vanilla's press runs and the tweaks watch the drag.
-    pub(super) fn tweak_press(&mut self, slot: Option<usize>, right: bool, shift: bool) -> bool {
+    pub(in crate::game) fn tweak_press(
+        &mut self,
+        slot: Option<usize>,
+        right: bool,
+        shift: bool,
+    ) -> bool {
         self.tweaks.drag = None;
         let Some(slot) = slot.filter(|&s| s != 200 && s < Creative::DISPLAY) else {
             return false;
@@ -174,7 +165,7 @@ impl Game<'_> {
     }
     /// The cursor moved while a button is held: true when the tweaks own
     /// the drag (vanilla's quick craft drag doesn't grow).
-    pub(super) fn tweak_drag_move(&mut self, slot: Option<usize>) -> bool {
+    pub(in crate::game) fn tweak_drag_move(&mut self, slot: Option<usize>) -> bool {
         let Some(mut drag) = self.tweaks.drag.take() else {
             return false;
         };
@@ -222,11 +213,11 @@ impl Game<'_> {
         owned
     }
     /// The button went up: the drag ends.
-    pub(super) fn tweak_release(&mut self) {
+    pub(in crate::game) fn tweak_release(&mut self) {
         self.tweaks.drag = None;
     }
     /// The wheel over an inventory screen: true when the tweaks used it.
-    pub(super) fn tweak_scroll(&mut self, delta: f32, slot: Option<usize>) -> bool {
+    pub(in crate::game) fn tweak_scroll(&mut self, delta: f32, slot: Option<usize>) -> bool {
         if !self.settings.extras.mouse_tweaks_wheel || !self.tweaks_on() || self.carried.is_some() {
             return false;
         }
@@ -356,144 +347,6 @@ impl Game<'_> {
     }
 }
 
-impl Game<'_> {
-    /// The sort buttons of the open screen, with the extra on: their
-    /// corner (from the screen's) and the slots each sorts. Any menu screen
-    /// gets them, by its slots' roles (`native_slot_roles`): one by the top
-    /// right of its storage slots (a chest's title line) when it has some,
-    /// one by the main inventory's (the "Inventory" label's line).
-    fn sort_buttons(&self) -> Vec<((f32, f32), Vec<usize>)> {
-        use super::NativeSlotRole as Role;
-        if !self.settings.extras.sort {
-            return Vec::new();
-        }
-        let roles = self.native_slot_roles();
-        let of = |role| -> Vec<usize> {
-            roles
-                .iter()
-                .filter(|(_, r)| *r == role)
-                .map(|(s, _)| *s)
-                .collect()
-        };
-        // Over the section's last column: (160, 5) over a chest's slots.
-        let right = |slots: &[usize]| {
-            slots
-                .iter()
-                .map(|&s| self.slot_position(s).0 + 8.0)
-                .fold(f32::MIN, f32::max)
-        };
-        let mut buttons = Vec::new();
-        let storage = of(Role::Storage);
-        if !storage.is_empty() {
-            let top = storage
-                .iter()
-                .map(|&s| self.slot_position(s).1 - 13.0)
-                .fold(f32::MAX, f32::min);
-            buttons.push(((right(&storage), top), storage));
-        }
-        // On the "Inventory" label's line (`inventoryLabelY`, height - 94, 12
-        // above the first row): a mod's screen places its inventory itself.
-        let main = of(Role::Inventory);
-        if !main.is_empty() {
-            let y = self
-                .native_screen_inventory_y()
-                .map_or(self.screen_height() - 95.0, |y| y - 13.0);
-            buttons.push(((right(&main), y), main));
-        }
-        buttons
-    }
-    /// The sort buttons: a bordered square with three bars, lighter under
-    /// the cursor.
-    pub(super) fn draw_sort_buttons(&self, batch: &mut HudBatch, ox: f32, oy: f32) {
-        let atlas = &self.gui.atlas;
-        for ((x, y), _) in self.sort_buttons() {
-            let (x, y) = (ox + x, oy + y);
-            let (cx, cy) = self.cursor;
-            let hovered = cx >= x && cx < x + SORT_BUTTON && cy >= y && cy < y + SORT_BUTTON;
-            let face = if hovered {
-                rgba(220, 220, 220, 255)
-            } else {
-                rgba(160, 160, 160, 255)
-            };
-            batch.fill(atlas, x, y, SORT_BUTTON, SORT_BUTTON, rgba(55, 55, 55, 255));
-            batch.fill(
-                atlas,
-                x + 1.0,
-                y + 1.0,
-                SORT_BUTTON - 2.0,
-                SORT_BUTTON - 2.0,
-                face,
-            );
-            for (i, w) in [5.0, 4.0, 3.0].into_iter().enumerate() {
-                let by = y + 2.0 + 2.0 * i as f32;
-                batch.fill(atlas, x + 2.0, by, w, 1.0, rgba(55, 55, 55, 255));
-            }
-        }
-    }
-    /// A left press on a sort button sorts its slots (true).
-    pub(super) fn sort_press(&mut self) -> bool {
-        let Some(r) = self.renderer.as_ref() else {
-            return false;
-        };
-        let batch = HudBatch::new([r.config.width, r.config.height]);
-        let (ox, oy) = self.inventory_origin(&batch);
-        let (cx, cy) = self.cursor;
-        let hit = self.sort_buttons().into_iter().find(|((x, y), _)| {
-            let (x, y) = (ox + x, oy + y);
-            cx >= x && cx < x + SORT_BUTTON && cy >= y && cy < y + SORT_BUTTON
-        });
-        let Some((_, slots)) = hit else {
-            return false;
-        };
-        self.sort_slots(&slots);
-        true
-    }
-    /// The sort key: sorts the part under the cursor (the container when
-    /// the cursor is over no slot).
-    pub(super) fn sort_key_press(&mut self, key: KeyCode) -> bool {
-        keybinds::key_name(key).is_some_and(|name| self.sort_input(name))
-    }
-    pub(super) fn sort_mouse_press(&mut self, button: MouseButton) -> bool {
-        self.sort_input(&keybinds::mouse_name(button))
-    }
-    fn sort_input(&mut self, name: &str) -> bool {
-        let e = &self.settings.extras;
-        if !e.sort || e.sort_key != name || self.recipe_search_focused() {
-            return false;
-        }
-        let buttons = self.sort_buttons();
-        let hovered = self.inventory_target().0;
-        let slots = buttons
-            .iter()
-            .find(|(_, slots)| hovered.is_some_and(|h| slots.contains(&h)))
-            .or(buttons.first())
-            .map(|(_, slots)| slots.clone());
-        let Some(slots) = slots else {
-            return false;
-        };
-        self.sort_slots(&slots);
-        true
-    }
-    /// Sorts `slots` with ordinary left clicks (needs an empty hand).
-    fn sort_slots(&mut self, slots: &[usize]) {
-        if self.carried.is_some() {
-            return;
-        }
-        let views: Vec<Option<ItemStack>> = slots.iter().map(|&s| self.slot_view(s)).collect();
-        let clicks = {
-            let rank = |s: &ItemStack| {
-                let order = self.creative_screen.order_of(s).unwrap_or(usize::MAX);
-                (order, hover_name(&self.pack.names, s))
-            };
-            let max = |s: &ItemStack| self.max_stack(s);
-            inv_sort::plan(&views, &rank, &max)
-        };
-        for i in clicks {
-            self.tweak_click(slots[i], 0, Input::Pickup);
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::tweak_menu;

crates/horizon-client/src/game/extras/sorting.rs

@@ -0,0 +1,155 @@
+//! Sorting (`sort`, `sortKey`; #332, `docs/extras.md`), off by default: a small button by a
+//! menu's storage slots and one by the inventory's (an optional key sorts the part under the
+//! cursor). The clicks come from `inv_sort::plan` and go through the Mouse Tweaks' ordinary slot
+//! clicks (`mouse_tweaks.rs`), so they work wherever vanilla's do.
+use crate::game::Game;
+use horizon_client::{
+    hud::{HudBatch, rgba},
+    inv_sort,
+    items::ItemStack,
+    keybinds,
+    menu::Input,
+    stations::hover_name,
+};
+use winit::{event::MouseButton, keyboard::KeyCode};
+
+/// A sort button's side in GUI pixels.
+const SORT_BUTTON: f32 = 9.0;
+
+impl Game<'_> {
+    /// The sort buttons of the open screen, with the extra on: their
+    /// corner (from the screen's) and the slots each sorts. Any menu screen
+    /// gets them, by its slots' roles (`native_slot_roles`): one by the top
+    /// right of its storage slots (a chest's title line) when it has some,
+    /// one by the main inventory's (the "Inventory" label's line).
+    fn sort_buttons(&self) -> Vec<((f32, f32), Vec<usize>)> {
+        use crate::game::NativeSlotRole as Role;
+        if !self.settings.extras.sort {
+            return Vec::new();
+        }
+        let roles = self.native_slot_roles();
+        let of = |role| -> Vec<usize> {
+            roles
+                .iter()
+                .filter(|(_, r)| *r == role)
+                .map(|(s, _)| *s)
+                .collect()
+        };
+        // Over the section's last column: (160, 5) over a chest's slots.
+        let right = |slots: &[usize]| {
+            slots
+                .iter()
+                .map(|&s| self.slot_position(s).0 + 8.0)
+                .fold(f32::MIN, f32::max)
+        };
+        let mut buttons = Vec::new();
+        let storage = of(Role::Storage);
+        if !storage.is_empty() {
+            let top = storage
+                .iter()
+                .map(|&s| self.slot_position(s).1 - 13.0)
+                .fold(f32::MAX, f32::min);
+            buttons.push(((right(&storage), top), storage));
+        }
+        // On the "Inventory" label's line (`inventoryLabelY`, height - 94, 12
+        // above the first row): a mod's screen places its inventory itself.
+        let main = of(Role::Inventory);
+        if !main.is_empty() {
+            let y = self
+                .native_screen_inventory_y()
+                .map_or(self.screen_height() - 95.0, |y| y - 13.0);
+            buttons.push(((right(&main), y), main));
+        }
+        buttons
+    }
+    /// The sort buttons: a bordered square with three bars, lighter under
+    /// the cursor.
+    pub(in crate::game) fn draw_sort_buttons(&self, batch: &mut HudBatch, ox: f32, oy: f32) {
+        let atlas = &self.gui.atlas;
+        for ((x, y), _) in self.sort_buttons() {
+            let (x, y) = (ox + x, oy + y);
+            let (cx, cy) = self.cursor;
+            let hovered = cx >= x && cx < x + SORT_BUTTON && cy >= y && cy < y + SORT_BUTTON;
+            let face = if hovered {
+                rgba(220, 220, 220, 255)
+            } else {
+                rgba(160, 160, 160, 255)
+            };
+            batch.fill(atlas, x, y, SORT_BUTTON, SORT_BUTTON, rgba(55, 55, 55, 255));
+            batch.fill(
+                atlas,
+                x + 1.0,
+                y + 1.0,
+                SORT_BUTTON - 2.0,
+                SORT_BUTTON - 2.0,
+                face,
+            );
+            for (i, w) in [5.0, 4.0, 3.0].into_iter().enumerate() {
+                let by = y + 2.0 + 2.0 * i as f32;
+                batch.fill(atlas, x + 2.0, by, w, 1.0, rgba(55, 55, 55, 255));
+            }
+        }
+    }
+    /// A left press on a sort button sorts its slots (true).
+    pub(in crate::game) fn sort_press(&mut self) -> bool {
+        let Some(r) = self.renderer.as_ref() else {
+            return false;
+        };
+        let batch = HudBatch::new([r.config.width, r.config.height]);
+        let (ox, oy) = self.inventory_origin(&batch);
+        let (cx, cy) = self.cursor;
+        let hit = self.sort_buttons().into_iter().find(|((x, y), _)| {
+            let (x, y) = (ox + x, oy + y);
+            cx >= x && cx < x + SORT_BUTTON && cy >= y && cy < y + SORT_BUTTON
+        });
+        let Some((_, slots)) = hit else {
+            return false;
+        };
+        self.sort_slots(&slots);
+        true
+    }
+    /// The sort key: sorts the part under the cursor (the container when
+    /// the cursor is over no slot).
+    pub(in crate::game) fn sort_key_press(&mut self, key: KeyCode) -> bool {
+        keybinds::key_name(key).is_some_and(|name| self.sort_input(name))
+    }
+    pub(in crate::game) fn sort_mouse_press(&mut self, button: MouseButton) -> bool {
+        self.sort_input(&keybinds::mouse_name(button))
+    }
+    fn sort_input(&mut self, name: &str) -> bool {
+        let e = &self.settings.extras;
+        if !e.sort || e.sort_key != name || self.recipe_search_focused() {
+            return false;
+        }
+        let buttons = self.sort_buttons();
+        let hovered = self.inventory_target().0;
+        let slots = buttons
+            .iter()
+            .find(|(_, slots)| hovered.is_some_and(|h| slots.contains(&h)))
+            .or(buttons.first())
+            .map(|(_, slots)| slots.clone());
+        let Some(slots) = slots else {
+            return false;
+        };
+        self.sort_slots(&slots);
+        true
+    }
+    /// Sorts `slots` with ordinary left clicks (needs an empty hand).
+    fn sort_slots(&mut self, slots: &[usize]) {
+        if self.carried.is_some() {
+            return;
+        }
+        let views: Vec<Option<ItemStack>> = slots.iter().map(|&s| self.slot_view(s)).collect();
+        let clicks = {
+            let rank = |s: &ItemStack| {
+                let order = self.creative_screen.order_of(s).unwrap_or(usize::MAX);
+                (order, hover_name(&self.pack.names, s))
+            };
+            let max = |s: &ItemStack| self.max_stack(s);
+            inv_sort::plan(&views, &rank, &max)
+        };
+        for i in clicks {
+            self.tweak_click(slots[i], 0, Input::Pickup);
+        }
+    }
+}

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

@@ -44,6 +44,7 @@ fn loaded_air_is_discarded_on_first_actual_game_tick() {
     game.block_ticks
         .add_empty_chunk(ChunkPos::new(0, 0))
         .unwrap();
+    game.load_ticking_neighbourhood(0, 0);
     assert!(game.run_command("forceload add 0 0"));
     assert!(game.run_command("fill 0 199 0 15 199 15 stone"));
     assert!(game.res.facts().is_air(game.world.block(4, 204, 4)));

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

@@ -67,6 +67,9 @@ fn game() -> Game<'static> {
             .add_empty_chunk(ChunkPos::new(x, 0))
             .unwrap();
     }
+    for x in 0..3 {
+        game.load_ticking_neighbourhood(x, 0);
+    }
     game.player = Some(PlayerMotion::new(game.motion, Vec3::new(24.5, 201.0, 12.5)).unwrap());
     let net = NetConfig {
         announce: false,

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

@@ -273,6 +273,7 @@ mod item_collision_tests {
         game.block_ticks
             .add_empty_chunk(ChunkPos::new(0, 0))
             .unwrap();
+        game.load_ticking_neighbourhood(0, 0);
         assert!(game.run_command("forceload add 0 0"));
         assert!(game.run_command("summon minecart 4.5 200 4.5"));
         assert!(game.run_command("summon oak_boat 10.5 200 10.5"));

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

@@ -55,6 +55,9 @@ fn game() -> Game<'static> {
             .chunks
             .insert((x, 0), Arc::new(Chunk::empty(x, 0)));
     }
+    for x in 0..2 {
+        game.load_ticking_neighbourhood(x, 0);
+    }
     assert!(game.run_command("fill 0 99 0 31 99 15 stone"));
     game.player = Some(PlayerMotion::new(game.motion, Vec3::new(28.5, 100.0, 10.5)).unwrap());
     let net = NetConfig {

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

@@ -56,6 +56,9 @@ fn game() -> Game<'static> {
             .add_empty_chunk(ChunkPos::new(cx, 0))
             .unwrap();
     }
+    for cx in 0..2 {
+        game.load_ticking_neighbourhood(cx, 0);
+    }
     for command in [
         "difficulty normal",
         "forceload add 0 0 31 15",

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

@@ -49,6 +49,7 @@ fn game() -> Game<'static> {
     game.block_ticks
         .add_empty_chunk(ChunkPos::new(0, 0))
         .unwrap();
+    game.load_ticking_neighbourhood(0, 0);
     for command in [
         "forceload add 0 0",
         "fill 0 99 0 15 99 15 stone",

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

@@ -694,7 +694,7 @@ impl Game<'_> {
         position: [f64; 3],
         velocity: [f64; 3],
     ) {
-        self.add_item_entity_drawn(stack, position, Some(velocity), true, 0);
+        self.add_item_entity_drawn(stack, position, Some(velocity), true, 0, 0);
     }
 
     pub(super) fn add_item_entity(
@@ -704,7 +704,21 @@ impl Game<'_> {
         velocity: Option<[f64; 3]>,
         pickup_delay: u32,
     ) -> [f64; 3] {
-        self.add_item_entity_drawn(stack, position, velocity, velocity.is_none(), pickup_delay)
+        self.add_item_entity_drawn(
+            stack,
+            position,
+            velocity,
+            velocity.is_none(),
+            pickup_delay,
+            0,
+        )
+    }
+
+    /// `spawnAtLocation` for a drop that then calls
+    /// `ItemEntity.setExtendedLifetime`: the item joins the world at `age`
+    /// instead of 0, so the wither's nether star lives 12000 ticks, not 6000.
+    pub(super) fn spawn_item_aged(&mut self, stack: ItemStack, position: [f64; 3], age: i32) {
+        self.add_item_entity_drawn(stack, position, None, true, 10, age);
     }
 
     /// `add_item_entity`; `constructor_motion` draws the five-argument
@@ -716,6 +730,7 @@ impl Game<'_> {
         velocity: Option<[f64; 3]>,
         constructor_motion: bool,
         pickup_delay: u32,
+        age: i32,
     ) -> [f64; 3] {
         let (item, count) = (stack.item.clone(), stack.count as i32);
         self.next_entity += 1;
@@ -738,6 +753,7 @@ impl Game<'_> {
             rotation: [yaw, 0.0],
             pickup_delay: i64::from(pickup_delay),
             random: own,
+            age,
             ..ItemEntity::new(
                 self.next_entity,
                 stack,
@@ -1017,14 +1033,10 @@ mod escape_tests {
         let mut game = server_game();
         let feet = horizon_core::geometry::Vec3::new(8.5, 70.0, 8.5);
         game.player = Some(horizon_client::motion::PlayerMotion::new(game.motion, feet).unwrap());
-        // Entity-ticking chunks also need the surrounding loaded chunks.
-        for x in -2..=2 {
-            for z in -2..=2 {
-                game.world
-                    .chunks
-                    .insert((x, z), Arc::new(Chunk::empty(x, z)));
-            }
-        }
+        game.world
+            .chunks
+            .insert((0, 0), Arc::new(Chunk::empty(0, 0)));
+        game.load_ticking_neighbourhood(0, 0);
         game.update_chunk_tickets();
         assert!(game.entity_ticking_area()(8, 8));
         let stone = game
@@ -1056,3 +1068,6 @@ mod escape_tests {
 #[cfg(test)]
 #[path = "item_void_tests.rs"]
 mod item_void_tests;
+#[cfg(test)]
+#[path = "wither_star_tests.rs"]
+mod wither_star_tests;

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

@@ -8,7 +8,7 @@ use horizon_client::{
     containers::{BlockEntity, Jukebox},
     first_person::Hand,
     items::ItemStack,
-    mobs::Species,
+    mobs::{Species, Who},
     particles::{ParticleOptions, ParticleType},
     text::Text,
 };
@@ -53,33 +53,49 @@ impl Game<'_> {
             _ => None,
         }
     }
-    fn set_has_record(&mut self, pos: [i32; 3], has: bool) {
-        self.set_has_record_notify(pos, has, true);
+    fn set_has_record(&mut self, pos: [i32; 3], has: bool) -> bool {
+        self.set_has_record_notify(pos, has, true)
     }
     /// The state change alone (`level.setBlock` with flag 2); `notify` adds
     /// `notifyItemChangedInJukebox`'s `block_change`, which
     /// `JukeboxBlock.setPlacedBy` does not post.
-    fn set_has_record_notify(&mut self, pos: [i32; 3], has: bool, notify: bool) {
+    fn set_has_record_notify(&mut self, pos: [i32; 3], has: bool, notify: bool) -> bool {
         let state = self.world.block(pos[0], pos[1], pos[2]);
         let registry = self.pack.assets.registry;
         let Some(mut s) = registry.state(state).cloned() else {
-            return;
+            return false;
         };
         s.properties.insert(
             "has_record".into(),
             if has { "true" } else { "false" }.into(),
         );
-        if let Some(new) = registry.id(&s) {
-            let p = BlockPos::new(pos[0], pos[1], pos[2]);
-            self.with_level(|b, level, ticks| {
-                b.set_block(level, ticks, p, new, level_flags::UPDATE_CLIENTS)
-            });
-            // `JukeboxBlockEntity.notifyItemChangedInJukebox`: the disc coming
-            // or going is a block change the sculk sensors hear.
-            if notify && self.world.block(pos[0], pos[1], pos[2]) != state {
-                self.post_block_game_event("minecraft:block_change", pos, None, Some(new));
-            }
+        let Some(new) = registry.id(&s) else {
+            return false;
+        };
+        let p = BlockPos::new(pos[0], pos[1], pos[2]);
+        self.with_level(|b, level, ticks| {
+            b.set_block(level, ticks, p, new, level_flags::UPDATE_CLIENTS)
+        });
+        if notify {
+            let state = self.world.block(pos[0], pos[1], pos[2]);
+            self.post_block_game_event("minecraft:block_change", pos, None, Some(state));
         }
+        true
+    }
+    /// `JukeboxBlock.HAS_RECORD`, the state both clicks are decided by.
+    fn jukebox_has_record(&self, pos: [i32; 3]) -> bool {
+        let state = self.world.block(pos[0], pos[1], pos[2]);
+        self.pack
+            .assets
+            .registry
+            .state(state)
+            .and_then(|s| s.properties.get("has_record"))
+            .is_some_and(|v| v == "true")
+    }
+    /// `JukeboxBlockEntity.notifyItemChangedInJukebox`: the block's
+    /// `has_record`, then `BLOCK_CHANGE` with the state it now has.
+    fn jukebox_record_changed(&mut self, pos: [i32; 3], has: bool) {
+        self.set_has_record(pos, has);
     }
     /// `JukeboxBlock.setPlacedBy`: a jukebox placed from an item whose
     /// `block_entity_data` carries a `RecordItem` keeps that record, so
@@ -121,9 +137,10 @@ impl Game<'_> {
         {
             j.playing = true;
             j.song_clock_present = true;
+            j.loaded_clock = false;
             j.ticks = 0;
         }
-        self.set_has_record(pos, true);
+        self.jukebox_record_changed(pos, true);
         self.start_song(pos, &song);
         self.jukebox_changed(pos);
     }
@@ -141,15 +158,17 @@ impl Game<'_> {
             was_playing = j.playing;
             j.playing = false;
             j.song_clock_present = false;
+            j.loaded_clock = false;
             j.ticks = 0;
         }
+        // `setTheItem(EMPTY)` first tells the block, then stops the song.
+        self.jukebox_record_changed(pos, false);
         // `JukeboxSongPlayer.stop` posts only while a song plays.
         if was_playing {
             self.stop_song_heard(pos);
         } else {
             self.stop_song(pos);
         }
-        self.set_has_record(pos, false);
         self.jukebox_changed(pos);
     }
     pub(super) fn jukebox_set_item(&mut self, pos: [i32; 3], stack: Option<ItemStack>) {
@@ -164,8 +183,9 @@ impl Game<'_> {
         j.items[0] = stack;
         j.playing = song.is_some();
         j.song_clock_present = song.is_some();
+        j.loaded_clock = false;
         j.ticks = 0;
-        self.set_has_record(pos, has_record);
+        self.jukebox_record_changed(pos, has_record);
         match song {
             Some(song) => self.start_song(pos, &song),
             None if was_playing => self.stop_song_heard(pos),
@@ -184,7 +204,10 @@ impl Game<'_> {
         {
             return false;
         }
-        if self.jukebox(pos).is_some_and(|j| j.record().is_some()) {
+        let state = self.world.block(pos[0], pos[1], pos[2]);
+        // The state, not the slot, decides the click: `JukeboxBlock` with a
+        // record pops it out, without one takes a disc.
+        if self.jukebox_has_record(pos) {
             // TRY_WITH_EMPTY_HAND: only the main hand goes on to useWithoutItem.
             if self.hand != Hand::Main {
                 return false;
@@ -199,7 +222,7 @@ impl Game<'_> {
         let Some(song) = jukebox_playable(stack, self.res.items()) else {
             return false;
         };
-        // JukeboxPlayable.tryInsertIntoJukebox
+        // JukeboxPlayable.tryInsertIntoJukebox: the one disc the player gives up.
         let record = ItemStack {
             count: 1,
             ..stack.clone()
@@ -207,7 +230,9 @@ impl Game<'_> {
         if !self.creative {
             self.consume_held();
         }
-        self.award_custom_stat("play_record", 1);
+        // `JukeboxBlockEntity.setTheItem`: the slot takes the disc, the block
+        // tells its listeners, and the song plays (`play`); a disc already in
+        // the slot (under a state that lost its record) is replaced.
         self.world.block_entities.insert(
             (pos[0], pos[1], pos[2]),
             BlockEntity::Jukebox(Jukebox {
@@ -215,13 +240,23 @@ impl Game<'_> {
                 ticks: 0,
                 playing: true,
                 song_clock_present: true,
+                loaded_clock: false,
             }),
         );
-        self.set_has_record(pos, true);
+        self.jukebox_record_changed(pos, true);
         if let Some(song) = song {
             self.start_song(pos, &song);
         }
         self.jukebox_changed(pos);
+        // `tryInsertIntoJukebox`: the same change again, against the state this
+        // click found, with the player as its source.
+        self.post_block_game_event(
+            "minecraft:block_change",
+            pos,
+            Some(Who::Player),
+            Some(state),
+        );
+        self.award_custom_stat("play_record", 1);
         // ServerPlayerGameMode.useItemOn: the action was consumed.
         self.trigger_block("minecraft:item_used_on_block", pos, stack);
         true
@@ -235,14 +270,8 @@ impl Game<'_> {
         if &*self.res.facts().get(state).name != "minecraft:jukebox" {
             return false;
         }
-        let has_record = self
-            .pack
-            .assets
-            .registry
-            .state(state)
-            .and_then(|s| s.properties.get("has_record"))
-            .is_some_and(|v| v == "true");
-        has_record || held.is_some_and(|stack| jukebox_playable(stack, self.res.items()).is_some())
+        self.jukebox_has_record(pos)
+            || held.is_some_and(|stack| jukebox_playable(stack, self.res.items()).is_some())
     }
     /// Level event 1010: the song from the jukebox, and the "Now Playing" overlay.
     fn start_song(&mut self, pos: [i32; 3], song: &str) {
@@ -317,20 +346,28 @@ impl Game<'_> {
             m.extra.party_jukebox = playing.then_some(pos);
         }
     }
-    /// `popOutTheItem`: the disc above the jukebox, and the song stops.
+    /// `popOutTheItem`: the disc above the jukebox, and the song stops. An
+    /// empty slot pops nothing out (`if (!itemBeforePoppingOut.isEmpty())`),
+    /// whatever the state says.
     fn eject_record(&mut self, pos: [i32; 3]) {
         let key = (pos[0], pos[1], pos[2]);
-        let mut was_playing = false;
-        let record = match self.world.block_entities.get_mut(&key) {
+        let (record, was_playing) = match self.world.block_entities.get_mut(&key) {
             Some(BlockEntity::Jukebox(j)) => {
-                was_playing = j.playing;
+                if j.items[0].is_none() {
+                    return;
+                }
+                let was_playing = j.playing;
                 j.playing = false;
                 j.song_clock_present = false;
+                j.loaded_clock = false;
                 j.ticks = 0;
-                j.items[0].take()
+                (j.items[0].take(), was_playing)
             }
-            _ => None,
+            _ => return,
         };
+        // `removeTheItem` -> `setTheItem(EMPTY)`: the block loses its record,
+        // then the song stops.
+        self.jukebox_record_changed(pos, false);
         // `JukeboxSongPlayer.stop` posts only while a song plays: a disc
         // taken out after its song ended is silent.
         if was_playing {
@@ -347,7 +384,6 @@ impl Game<'_> {
             );
             self.spawn_item_own(record, at, 10);
         }
-        self.set_has_record(pos, false);
         self.jukebox_changed(pos);
     }
     /// A broken jukebox stops its song (its disc drops with the contents).
@@ -359,11 +395,11 @@ impl Game<'_> {
         let playing = match self.world.block_entities.get(&key) {
             Some(BlockEntity::Jukebox(j)) if j.playing => j.record().and_then(|r| {
                 let song = song_of_record(r, self.items())?;
-                Some((song, j.ticks))
+                Some((song, j.ticks, j.loaded_clock))
             }),
             _ => None,
         };
-        let Some((song, ticks)) = playing else {
+        let Some((song, ticks, loaded)) = playing else {
             return;
         };
         let pos = [key.0, key.1, key.2];
@@ -374,13 +410,26 @@ impl Game<'_> {
             if let Some(BlockEntity::Jukebox(j)) = self.world.block_entities.get_mut(&key) {
                 j.playing = false;
                 j.song_clock_present = false;
+                j.loaded_clock = false;
                 j.ticks = 0;
             }
+            // `setSongWithoutPlaying` never adopted a clock past its song's
+            // end: loading such a jukebox is silent, while a song that ends
+            // here stops out loud.
+            if loaded {
+                return;
+            }
             self.stop_song_heard(pos);
             self.jukebox_changed(pos);
             return;
         }
-        if !self.jukebox_sounds.contains_key(&key) && ticks == 0 {
+        if loaded {
+            // The song a save kept goes on without its sound: vanilla starts
+            // one only from `play` (level event 1010).
+            if let Some(BlockEntity::Jukebox(j)) = self.world.block_entities.get_mut(&key) {
+                j.loaded_clock = false;
+            }
+        } else if !self.jukebox_sounds.contains_key(&key) && ticks == 0 {
             self.start_song(pos, &song);
         }
         if ticks % 20 == 0 {
@@ -452,12 +501,19 @@ pub(super) fn jukebox_signals(
 ) -> Option<(i32, i32)> {
     match world.block_entities.get(&(pos.x, pos.y, pos.z)) {
         Some(BlockEntity::Jukebox(j)) => {
-            let comparator = j
-                .record()
-                .and_then(|r| song_of_record(r, items))
-                .and_then(|s| items.songs.get(&s).map(|song| song.comparator))
+            let song = j.record().and_then(|r| song_of_record(r, items));
+            let comparator = song
+                .as_deref()
+                .and_then(|s| items.songs.get(s).map(|song| song.comparator))
                 .unwrap_or(0);
-            Some((if j.playing { 15 } else { 0 }, comparator))
+            // `JukeboxSongPlayer.isPlaying`, less a clock a save brought back
+            // past its song's end: the first tick drops that one.
+            let stale = j.loaded_clock
+                && song
+                    .as_deref()
+                    .and_then(|s| items.songs.get(s))
+                    .is_some_and(|s| s.finished(j.ticks));
+            Some((if j.playing && !stale { 15 } else { 0 }, comparator))
         }
         _ => None,
     }
@@ -578,18 +634,24 @@ mod jukebox_play_tests {
         );
         // The song is still playing after 41 ticks.
         assert!(
-            lines.iter().all(|l| l.ends_with("minecraft:jukebox_play")),
+            !lines
+                .iter()
+                .any(|l| l.ends_with("minecraft:jukebox_stop_play")),
             "{lines:?}"
         );
     }
 
     /// A jukebox whose song is stopped posts no play event: only the twenty
-    /// ticks of a playing song do.
+    /// ticks of a playing song do. Its insert's `BLOCK_CHANGE` events are the
+    /// only ones there.
     #[test]
     #[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
     fn a_stopped_jukebox_posts_no_play_event() {
         let Some(lines) = playing(0) else { return };
-        assert!(lines.is_empty(), "{lines:?}");
+        assert!(
+            lines.iter().all(|l| l.ends_with("minecraft:block_change")),
+            "{lines:?}"
+        );
     }
 }
 
@@ -656,7 +718,8 @@ mod saved_song_clock_tests {
         assert!(game.run_command("setblock 8 199 4 stone"));
         assert!(game.run_command("setblock 8 200 4 jukebox[has_record=true]{RecordItem:{id:\"minecraft:music_disc_cat\",count:1,components:{\"minecraft:custom_data\":{h032:1}}}}"));
         let j = game.jukebox([8, 200, 4]).unwrap();
-        assert!(j.playing, "preserve legacy record-only adoption");
+        // `setSongWithoutPlaying`: a record whose save had no clock is silent.
+        assert!(!j.playing, "a record without a clock does not play on load");
         assert_eq!(j.ticks, 0);
         let saved = game.block_entity_nbt([8, 200, 4]).unwrap();
         assert_eq!(
@@ -692,6 +755,7 @@ mod jukebox_component_tests {
                 ticks: 0,
                 song_clock_present: true,
                 playing: true,
+                loaded_clock: false,
             }),
         );
         jukebox_signals(
@@ -775,6 +839,10 @@ mod jukebox_component_tests {
     }
 }
 
+#[cfg(test)]
+#[path = "jukebox_tests.rs"]
+mod jukebox_tests;
+
 #[cfg(test)]
 mod block_change_tests {
     use super::*;

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

@@ -0,0 +1,288 @@
+//! Jukeboxes against `JukeboxBlock`, `JukeboxBlockEntity` and `JukeboxPlayable`:
+//! what a load brings back of a saved song, the `BLOCK_CHANGE` of an insert and
+//! of an eject, and which click the `has_record` state allows.
+use super::Game;
+use crate::game::{Audio, Options, Progress, Settings, load_resources};
+use horizon_client::{
+    chunk::Chunk,
+    containers::{BlockEntity, Jukebox},
+    items::ItemStack,
+    mobs::Who,
+};
+use horizon_world::registry::BlockStateId;
+use std::sync::Arc;
+
+/// The game events posted while `f` runs, as `(event, position, source)`.
+fn record(f: impl FnOnce()) -> Vec<(&'static str, [f64; 3], Option<Who>)> {
+    crate::game::sculk::TEST_POSTED_EVENTS.with(|e| *e.borrow_mut() = Some(Vec::new()));
+    f();
+    crate::game::sculk::TEST_POSTED_EVENTS.with(|e| e.borrow_mut().take().unwrap_or_default())
+}
+
+/// A windowless integrated-server game from the prepared resources with a
+/// resident chunk; `None` without them.
+fn with_game<R>(f: impl FnOnce(&mut Game<'static>) -> R) -> Option<R> {
+    let root = std::path::PathBuf::from(std::env::var_os("HORIZON_TEST_RESOURCES")?);
+    let settings = Settings::default();
+    let loaded = load_resources(
+        root.clone(),
+        None,
+        &root,
+        &settings,
+        std::time::Instant::now(),
+        false,
+        true,
+        &Progress::new(),
+        &mut |_, _| unreachable!(),
+    )
+    .ok()?;
+    let mut options = Options::parse(std::iter::empty()).unwrap().unwrap();
+    options.resources = root.clone();
+    options.execution_role = crate::game::execution_role::ExecutionRole::IntegratedServer;
+    let res: &'static _ = Box::leak(Box::new(loaded.resources));
+    let mut game = Game::new(
+        res,
+        loaded.pack,
+        loaded.gui.unwrap(),
+        options,
+        settings,
+        Audio::silent(&root),
+        None,
+    )
+    .unwrap();
+    game.world
+        .chunks
+        .insert((0, 0), Arc::new(Chunk::empty(0, 0)));
+    Some(f(&mut game))
+}
+
+const AT: [f64; 3] = [0.5, 64.5, 0.5];
+
+/// The jukebox at (0, 64, 0) in the state `record` names; its state id.
+fn place_jukebox(game: &mut Game<'_>, record: bool) -> BlockStateId {
+    let registry = game.pack.assets.registry;
+    let mut state = registry
+        .state(registry.default_state("minecraft:jukebox").unwrap())
+        .unwrap()
+        .clone();
+    state.properties.insert(
+        "has_record".into(),
+        if record { "true" } else { "false" }.into(),
+    );
+    let id = registry.id(&state).unwrap();
+    game.world.set(0, 64, 0, id).unwrap();
+    id
+}
+
+/// A jukebox block entity as a save writes it, loaded back into the world at
+/// (0, 64, 0): `RecordItem` and, with a `clock`, `ticks_since_song_started`.
+fn load_saved(game: &mut Game<'_>, clock: Option<i64>) {
+    let clock = clock.map_or(String::new(), |n| format!("ticks_since_song_started:{n}L,"));
+    let (tag, _) = horizon_world::nbt::parse_snbt(&format!(
+        "{{id:\"minecraft:jukebox\",x:0,y:64,z:0,\
+         RecordItem:{{id:\"minecraft:music_disc_11\",count:1,}},{clock}}}"
+    ))
+    .unwrap();
+    let (pos, model) = horizon_client::save::decode_block_entity(&tag).unwrap();
+    game.world.block_entities.insert(pos, model);
+}
+
+/// `JukeboxBlockEntity.setTheItem` posts `BLOCK_CHANGE` with the state the
+/// block now has, and `JukeboxPlayable.tryInsertIntoJukebox` then posts the
+/// same change again with the player as its source (against the state the
+/// click found). `popOutTheItem` -> `setTheItem(EMPTY)` posts one on the way
+/// out, before the song's own `JUKEBOX_STOP_PLAY`. A sculk sensor beside a
+/// jukebox heard neither insert nor eject: only the song's end.
+#[test]
+#[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
+fn an_insert_posts_two_block_changes_and_an_eject_one() {
+    let Some((inserted, popped)) = with_game(|game| {
+        place_jukebox(game, false);
+        let disc = ItemStack::new("minecraft:music_disc_cat", 1);
+        let inserted = record(|| {
+            assert!(
+                game.use_jukebox([0, 64, 0], Some(&disc)),
+                "the disc goes in"
+            );
+        });
+        let popped = record(|| {
+            assert!(
+                game.use_jukebox([0, 64, 0], None),
+                "the empty hand pops it out"
+            );
+        });
+        (inserted, popped)
+    }) else {
+        return;
+    };
+    assert_eq!(
+        inserted,
+        vec![
+            ("minecraft:block_change", AT, None),
+            ("minecraft:block_change", AT, Some(Who::Player)),
+        ],
+        "the slot's change, then the player's"
+    );
+    assert_eq!(
+        popped,
+        vec![
+            ("minecraft:block_change", AT, None),
+            ("minecraft:jukebox_stop_play", AT, None),
+        ],
+        "the record leaves the block before its song stops"
+    );
+}
+
+/// `JukeboxBlock.useWithoutItem` only pops when the state says a record is
+/// there, and `popOutTheItem` pops nothing from an empty slot; `useItemOn`
+/// only inserts when it says there is none, and replacing the slot's item is
+/// `setTheItem`'s own doing. Horizon decided both by the slot.
+#[test]
+#[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
+fn the_has_record_state_decides_both_clicks() {
+    let Some((ignored, replaced)) = with_game(|game| {
+        // has_record with nothing in the slot: the click pops nothing and the
+        // disc stays in hand, so the state stays as it is.
+        let recorded = place_jukebox(game, true);
+        game.world
+            .block_entities
+            .insert((0, 64, 0), BlockEntity::Jukebox(Jukebox::default()));
+        let disc = ItemStack::new("minecraft:music_disc_cat", 1);
+        let ignored = record(|| {
+            assert!(
+                game.use_jukebox([0, 64, 0], Some(&disc)),
+                "the click is consumed"
+            );
+        });
+        assert_eq!(game.world.block(0, 64, 0), recorded, "keeps its record");
+        assert!(
+            game.jukebox([0, 64, 0]).unwrap().record().is_none(),
+            "the held disc is not inserted"
+        );
+
+        // No record in the state with a disc in the slot: the held one replaces
+        // it (`JukeboxBlockEntity.setTheItem`), it does not eject the old one.
+        place_jukebox(game, false);
+        let old = ItemStack::new("minecraft:music_disc_13", 1);
+        game.world.block_entities.insert(
+            (0, 64, 0),
+            BlockEntity::Jukebox(Jukebox {
+                items: [Some(old)],
+                ..Default::default()
+            }),
+        );
+        let replaced = record(|| {
+            assert!(
+                game.use_jukebox([0, 64, 0], Some(&disc)),
+                "the disc goes in"
+            );
+        });
+        let j = game.jukebox([0, 64, 0]).unwrap();
+        assert_eq!(&*j.record().unwrap().item, "minecraft:music_disc_cat");
+        assert!(j.playing, "the new disc plays");
+        (ignored, replaced)
+    }) else {
+        return;
+    };
+    assert!(ignored.is_empty(), "nothing happened: {ignored:?}");
+    assert_eq!(
+        replaced,
+        vec![
+            ("minecraft:block_change", AT, None),
+            ("minecraft:block_change", AT, Some(Who::Player)),
+        ],
+        "the old disc is replaced, not popped out"
+    );
+}
+
+/// `JukeboxBlockEntity.loadAdditional` hands a saved clock to
+/// `JukeboxSongPlayer.setSongWithoutPlaying`: a song under its length comes
+/// back playing, without `play`'s level event 1010 and its "Now Playing", a
+/// clock past the song's end is dropped without a `JUKEBOX_STOP_PLAY`, and a
+/// record saved without a clock is no song at all.
+#[test]
+#[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
+fn a_saved_song_comes_back_without_its_sound() {
+    let Some(cases) = with_game(|game| {
+        place_jukebox(game, true);
+        let signal = |game: &Game<'_>| {
+            let p = horizon_core::position::BlockPos::new(0, 64, 0);
+            super::jukebox_signals(&game.world, game.items(), p)
+                .unwrap()
+                .0
+        };
+        let mut cases = Vec::new();
+        for clock in [Some(41), Some(10_000), None, Some(0)] {
+            load_saved(game, clock);
+            let events = record(|| game.tick_jukebox((0, 64, 0)));
+            let j = game.jukebox([0, 64, 0]).unwrap();
+            cases.push((
+                clock,
+                (j.playing, j.ticks, j.song_clock_present),
+                signal(game),
+                game.titles.overlay.is_some(),
+                events,
+            ));
+        }
+        cases
+    }) else {
+        return;
+    };
+    let at = |clock: Option<i64>| cases.iter().find(|c| c.0 == clock).unwrap();
+    // Mid-song and at its start: the clock goes on, at 15, quietly; only the
+    // twenty-tick chatter of a song that is running.
+    assert_eq!(at(Some(41)).1, (true, 42, true), "the clock goes on");
+    assert_eq!(at(Some(41)).2, 15);
+    assert!(!at(Some(41)).3, "nothing says \"Now Playing\" on a load");
+    assert!(at(Some(41)).4.is_empty(), "{:?}", at(Some(41)).4);
+    assert_eq!(at(Some(0)).1, (true, 1, true));
+    assert!(!at(Some(0)).3, "a clock saved at its start stays quiet");
+    assert_eq!(
+        at(Some(0)).4,
+        vec![("minecraft:jukebox_play", AT, None)],
+        "the first tick's game event is vanilla's"
+    );
+    // Past the end: gone, and silent about going.
+    assert_eq!(at(Some(10_000)).1, (false, 0, false));
+    assert_eq!(at(Some(10_000)).2, 0, "a dropped song powers nothing");
+    assert!(at(Some(10_000)).4.is_empty(), "{:?}", at(Some(10_000)).4);
+    // A record saved without a clock: no song, no signal, no event.
+    assert_eq!(at(None).1, (false, 0, false));
+    assert_eq!(at(None).2, 0);
+    assert!(!at(None).3, "a record alone starts no song");
+    assert!(at(None).4.is_empty(), "{:?}", at(None).4);
+}
+
+/// The same three cases on the load path itself, which needs no resources: only
+/// a saved clock brings a song back, and it comes back unstarted.
+#[test]
+fn only_a_saved_clock_brings_a_song_back() {
+    let load = |clock: Option<i64>| {
+        let clock = clock.map_or(String::new(), |n| format!("ticks_since_song_started:{n}L,"));
+        let (tag, _) = horizon_world::nbt::parse_snbt(&format!(
+            "{{id:\"minecraft:jukebox\",x:0,y:64,z:0,\
+             RecordItem:{{id:\"minecraft:music_disc_11\",count:1,}},{clock}}}"
+        ))
+        .unwrap();
+        match horizon_client::save::decode_block_entity(&tag).unwrap().1 {
+            BlockEntity::Jukebox(j) => j,
+            other => panic!("not a jukebox: {other:?}"),
+        }
+    };
+    let mid = load(Some(41));
+    assert_eq!(mid.ticks, 41);
+    assert!(
+        mid.playing && mid.song_clock_present,
+        "a saved clock brings the song back"
+    );
+    let unclocked = load(None);
+    assert_eq!(
+        unclocked.record().map(|r| &*r.item),
+        Some("minecraft:music_disc_11")
+    );
+    assert_eq!(unclocked.ticks, 0);
+    assert!(
+        !unclocked.playing && !unclocked.song_clock_present,
+        "a record alone is no song"
+    );
+}

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

@@ -47,6 +47,7 @@ fn game() -> Game<'static> {
     game.block_ticks
         .add_empty_chunk(ChunkPos::new(0, 0))
         .unwrap();
+    game.load_ticking_neighbourhood(0, 0);
     for command in [
         "forceload add 0 0",
         "fill 0 63 0 15 63 15 stone",

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

@@ -1161,7 +1161,7 @@ impl Game<'_> {
         let scale = 1i32 << m.scale;
         let start_x = m.center[0] / scale - 64;
         let start_z = m.center[1] / scale - 64;
-        let sea_level = 63;
+        let sea_level = horizon_world::level::sea_level_of(self.level_key());
         let quarts: Vec<[i32; 3]> = (0..128)
             .flat_map(|row| {
                 (0..128).map(move |column| {

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

@@ -656,10 +656,16 @@ impl Game<'_> {
                 self.station_sound(sound);
             }
         } else if kind == Kind::Stonecutter {
+            // `StonecutterMenu.container`'s listener runs on every change of the
+            // input slot (`slotsChanged` and `containerChanged` both hang off
+            // it): a recipe button or an inventory click is not one.
+            let input_changed = before[0] != menu.slot(0).cloned();
             if let Some(s) = self.station.as_mut() {
                 s.selected = usize::try_from(menu.data[0]).ok();
                 s.stone = std::mem::take(&mut menu.stone);
-                s.stonecutter_changed();
+                if input_changed {
+                    s.stonecutter_changed();
+                }
             }
             for sound in sounds.into_iter().filter(|_| !predicting) {
                 self.station_sound(sound);

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

@@ -233,6 +233,19 @@ fn pickup_instead_of_push(species: Species, is_passenger: bool, cart_is_vehicle:
     !cart_is_vehicle && !is_passenger && species != Species::IronGolem
 }
 
+/// `EntitySelector.pushableBy` asks `isPushable`: `Shulker` takes no push
+/// (`Mob::pushable` leaves it out) but still counts, so a cart offers it
+/// `startRiding` like any other living entity.
+fn offered_pickup(pushable: bool, species: Species, alive: bool) -> bool {
+    pushable || species == Species::Shulker && alive
+}
+
+/// `Shulker.push(Entity)` is empty, so a shulker that is not picked up (it
+/// already rides something) neither moves nor slows the cart.
+fn takes_push_from_cart(species: Species) -> bool {
+    species != Species::Shulker
+}
+
 /// `Entity.canRide` for a cart: the boarding cooldown, and a warden or the
 /// wither never rides (`canRide` false).
 fn can_ride_cart(species: Species, boarding_cooldown: i32) -> bool {
@@ -1794,7 +1807,10 @@ impl Game<'_> {
             let (teams, own) = (self.mob_teams(), self.team_with_owner(id, || None));
             near.iter()
                 .map(|&j| &self.mobs[j as usize])
-                .filter(|m| m.pushable() && pushable_by(own, teams.of(Who::Mob(m.id)), true))
+                .filter(|m| {
+                    offered_pickup(m.pushable(), m.species(), m.alive())
+                        && pushable_by(own, teams.of(Who::Mob(m.id)), true)
+                })
                 .map(|m| m.id)
                 .collect()
         };
@@ -1827,6 +1843,9 @@ impl Game<'_> {
                 }
                 continue;
             }
+            if !takes_push_from_cart(species) {
+                continue;
+            }
             let other = self.mobs[j].position;
             let Some(v) = super::boat_passengers::push_impulse(pos, other) else {
                 continue;
@@ -2144,51 +2163,6 @@ impl Game<'_> {
             p.velocity = Vec3::ZERO;
         }
     }
-    /// `EntityType.createDefaultStackConfig` on a vehicle an item made: the
-    /// item's custom name and custom data (`applyComponentsFromItemStack`:
-    /// `Entity.applyImplicitComponent`'s two, saved as `CustomName` and
-    /// `data`), then its
-    /// `minecraft:entity_data` loaded over the vehicle (`updateCustomEntityTag`)
-    /// when it names this type. An op-only type (command block and spawner
-    /// minecarts) takes it from an op player only, never from a dispenser
-    /// (`by_player` false).
-    pub(super) fn apply_vehicle_stack_config(
-        &mut self,
-        target: super::commands::Target,
-        kind: &str,
-        stack: &ItemStack,
-        by_player: bool,
-    ) {
-        use horizon_world::nbt::Tag;
-        let name = stack.data().and_then(|d| d.custom_name.clone());
-        let custom = stack
-            .data()
-            .and_then(|d| d.other("minecraft:custom_data"))
-            .cloned();
-        let op = by_player && self.acting_player_is_op();
-        let data =
-            horizon_client::block_entity_item::spawn_egg_entity_data(stack, kind, op).cloned();
-        if name.is_none() && custom.is_none() && data.is_none() {
-            return;
-        }
-        let Some(mut own) = self.entity_nbt(target) else {
-            return;
-        };
-        if let Tag::Compound(map) = &mut own {
-            if let Some(name) = name {
-                map.insert("CustomName".into(), name);
-            }
-            if let Some(custom) = custom {
-                map.insert("data".into(), custom);
-            }
-        }
-        let tag = match &data {
-            Some(data) => horizon_client::data_cmd::merged(&own, data),
-            None => own,
-        };
-        // The vehicle's own compound, its name and data merged in: it loads back.
-        let _ = self.apply_entity_nbt(target, tag);
-    }
     /// `MinecartItem.useOn`: a cart on the clicked rail.
     pub(super) fn place_minecart(&mut self, hit: &Hit, stack: &ItemStack) -> bool {
         let Some(kind) = CartKind::from_id(&stack.item) else {
@@ -2210,7 +2184,7 @@ impl Game<'_> {
             .insert((hit.pos[0] >> 4, hit.pos[2] >> 4));
         self.carts.push(cart);
         let id = self.next_entity;
-        self.apply_vehicle_stack_config(super::commands::Target::Cart(id), kind.id(), stack, true);
+        self.apply_item_stack_config(super::commands::Target::Cart(id), kind.id(), stack, true);
         if self.serving.is_some() || self.options.dedicated.is_some() {
             let cart = self.carts.last().unwrap();
             self.native_vehicle_create(
@@ -3382,6 +3356,25 @@ mod tests {
         assert!(!can_ride_cart(Species::Warden, 0));
     }
 
+    /// A shulker beside the rail is picked up although `Mob::pushable` leaves it out.
+    #[test]
+    fn a_cart_picks_up_a_shulker_but_not_a_dead_one() {
+        assert!(offered_pickup(false, Species::Shulker, true));
+        assert!(!offered_pickup(false, Species::Shulker, false));
+        assert!(!offered_pickup(false, Species::Bat, true));
+        assert!(offered_pickup(true, Species::Cow, true));
+        assert!(pickup_instead_of_push(Species::Shulker, false, false));
+        assert!(can_ride_cart(Species::Shulker, 0));
+    }
+
+    /// A shulker already riding a boat is no pickup candidate and `Shulker.push` is a no-op.
+    #[test]
+    fn a_mounted_shulker_does_not_push_a_cart() {
+        assert!(!pickup_instead_of_push(Species::Shulker, true, false));
+        assert!(!takes_push_from_cart(Species::Shulker));
+        assert!(takes_push_from_cart(Species::Cow));
+    }
+
     /// `WitherBoss.canRide` returns false, so a moving cart cannot scoop the boss up.
     #[test]
     fn a_wither_never_rides_a_cart() {

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

@@ -268,3 +268,40 @@ fn efficiency_applies_to_a_same_item_swap() {
         }
     });
 }
+
+#[test]
+#[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
+fn a_stacks_attribute_modifiers_replace_its_items_attack_damage() {
+    with_survival_game(|game| {
+        // Player.attack reads getAttributeValue(ATTACK_DAMAGE): the base 1
+        // plus what detectEquipmentUpdates gave the player for the held stack
+        // (ItemStack.forEachModifier, the stack's ATTRIBUTE_MODIFIERS). An
+        // iron pickaxe's own modifier is +3 (ToolMaterial.IRON's 2 plus the
+        // pickaxe's 1); the stack's +20 replaces it, so the hit is 21 (#14641).
+        for (stack, damage) in [
+            ("minecraft:iron_pickaxe", 4.0),
+            (
+                "minecraft:iron_pickaxe[attribute_modifiers=[{type:\"minecraft:attack_damage\",id:\"minecraft:base_attack_damage\",amount:20.0,operation:\"add_value\",slot:\"mainhand\"}]]",
+                21.0,
+            ),
+            // Identifier.CODEC reads bare names as `minecraft:`'s: the same
+            // modifier, so the attribute the host applies it to is found.
+            (
+                "minecraft:iron_pickaxe[attribute_modifiers=[{type:\"attack_damage\",id:\"base_attack_damage\",amount:20.0,operation:\"add_value\",slot:\"mainhand\"}]]",
+                21.0,
+            ),
+            // In the off hand slot group, it does not apply to the main hand.
+            (
+                "minecraft:iron_pickaxe[attribute_modifiers=[{type:\"minecraft:attack_damage\",id:\"minecraft:base_attack_damage\",amount:20.0,operation:\"add_value\",slot:\"offhand\"}]]",
+                1.0,
+            ),
+            ("minecraft:iron_pickaxe[!attribute_modifiers]", 1.0),
+        ] {
+            assert!(game.run_command(&format!(
+                "item replace entity @s weapon.mainhand with {stack}"
+            )));
+            game.tick_hand();
+            assert_eq!(game.attack_damage(), damage, "{stack}");
+        }
+    });
+}

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

@@ -44,18 +44,13 @@ fn game() -> Game<'static> {
     .unwrap();
     game.build_registries();
     game.set_allow_commands(true);
-    // Entities tick once every chunk within 2 columns is loaded
-    // (ChunkMap.prepareEntityTickingChunk, #13953).
-    for x in -2..=2 {
-        for z in -2..=2 {
-            game.world
-                .chunks
-                .insert((x, z), Arc::new(Chunk::empty(x, z)));
-            game.block_ticks
-                .add_empty_chunk(ChunkPos::new(x, z))
-                .unwrap();
-        }
-    }
+    game.world
+        .chunks
+        .insert((0, 0), Arc::new(Chunk::empty(0, 0)));
+    game.block_ticks
+        .add_empty_chunk(ChunkPos::new(0, 0))
+        .unwrap();
+    game.load_ticking_neighbourhood(0, 0);
     assert!(game.run_command("fill 0 99 0 15 99 15 stone"));
     game
 }

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

@@ -992,6 +992,8 @@
 use super::native_data_maps::NativeDataMapType;
 use super::native_guards::{box_meets, finite, finite_params, mod_image_fits};
 use super::native_item_energy::ItemEnergyBuffer;
+use super::native_level_effects::{mod_particles_ok, mod_sound_ok, sound_id};
+use super::native_menus::viewer_changes;
 use super::native_world_edit::{property_change, with_property};
 use super::{
     Game, GameLevel, LevelDimension, Screen,
@@ -8504,6 +8506,18 @@ impl Game<'_> {
             blocks,
         );
     }
+    /// An explosion at `center` in `dimension` is about to hurt and push `entities`, the ids of
+    /// the entities in its reach (players aside: `native_living_incoming_damage` hears them),
+    /// after `native_explosion_detonate`: `ServerExplosion.hurtEntities`. Take out the ids to
+    /// spare: they are neither hurt nor pushed. Server-side. API @API:explosion_entities@.
+    pub(super) fn native_explosion_entities(
+        &mut self,
+        dimension: &str,
+        center: [f64; 3],
+        entities: &mut Vec<u32>,
+    ) {
+        mod_api::dispatch_explosion_entities(self, mod_api::mods(), dimension, center, entities);
+    }
     /// An explosion at `center` in `dimension`, about to break `blocks`, pushes
     /// `entity` (None for a player, whom `native_acting_player` names):
     /// `ServerExplosion.hurtEntities`, after the knockback is calculated. Change `knockback_velocity` to change
@@ -9991,113 +10005,6 @@ fn mob_source(damage: &Damage) -> HurtSource<'static> {
     }
 }
 
-/// Whether `id` is a sound event's id, `namespace:path` as `Identifier`
-/// allows: the namespace of `[a-z0-9_.-]`, the path also with `/`.
-/// Whether a native mod's sound can be sent: a namespaced event, a sound
-/// source, a position inside the world's range and a finite, non-negative
-/// volume and pitch.
-pub(super) fn mod_sound_ok(
-    sound: &str,
-    at: [f64; 3],
-    source: usize,
-    volume: f32,
-    pitch: f32,
-) -> bool {
-    let position_ok = at
-        .into_iter()
-        .all(|v| v.is_finite() && v.abs() <= f64::from(i32::MAX) / 8.0);
-    let gain_ok = volume.is_finite() && volume >= 0.0 && pitch.is_finite() && pitch >= 0.0;
-    sound_id(sound)
-        && source < horizon_client::settings::SOUND_SOURCES.len()
-        && position_ok
-        && gain_ok
-}
-
-/// Whether a native mod's particles can be sent. Block particle types need
-/// a known state (`state_ok`); item, trail and vibration particles aren't
-/// supported by the network dispatch; a mod's own type must be namespaced.
-pub(super) fn mod_particles_ok(
-    options: &ParticleOptions,
-    state: Option<BlockStateId>,
-    state_ok: impl Fn(BlockStateId) -> bool,
-    at: [f64; 3],
-    spread: [f64; 3],
-    speed: f64,
-) -> bool {
-    use ParticleType as T;
-    // A native mod's own type: the name has to be namespaced, and a client
-    // draws it only when its pack has the sprite set.
-    if let Some(name) = &options.mod_particle {
-        let namespaced = name
-            .split_once(':')
-            .is_some_and(|(ns, path)| !ns.is_empty() && !path.is_empty());
-        if !namespaced {
-            return false;
-        }
-    }
-    let supported = match options.ty {
-        T::Block | T::BlockMarker | T::FallingDust | T::DustPillar | T::BlockCrumble => {
-            state.is_some_and(state_ok)
-        }
-        T::Item | T::Trail | T::Vibration => false,
-        T::Geyser | T::GeyserPlume | T::GeyserBase | T::GeyserPoof => options
-            .geyser
-            .is_some_and(|(_, impulse)| impulse.is_finite()),
-        _ => true,
-    };
-    supported
-        && at.into_iter().all(f64::is_finite)
-        && spread
-            .into_iter()
-            .all(|v| v.is_finite() && v.abs() <= f32::MAX as f64)
-        && speed.is_finite()
-        && speed.abs() <= f32::MAX as f64
-        && options.color.into_iter().all(f32::is_finite)
-        && options.to_color.into_iter().all(f32::is_finite)
-        && options.scale.is_finite()
-}
-
-fn sound_id(id: &str) -> bool {
-    let Some((namespace, path)) = id.split_once(':') else {
-        return false;
-    };
-    let allowed = |c: char, slash: bool| {
-        c.is_ascii_lowercase() || c.is_ascii_digit() || "_.-".contains(c) || (slash && c == '/')
-    };
-    !namespace.is_empty()
-        && !path.is_empty()
-        && namespace.chars().all(|c| allowed(c, false))
-        && path.chars().all(|c| allowed(c, true))
-}
-
-/// Sets the viewer counts `known` holds for `dim` to `now` and returns the
-/// changes as `(pos, previous, viewers)`, in position order. A container that
-/// is no longer counted goes to 0 and leaves `known`.
-pub(super) fn viewer_changes(
-    known: &mut HashMap<(&'static str, (i32, i32, i32)), u32>,
-    dim: &'static str,
-    mut now: HashMap<(i32, i32, i32), u32>,
-) -> Vec<((i32, i32, i32), u32, u32)> {
-    let mut changes = Vec::new();
-    known.retain(|&(d, pos), previous| {
-        if d != dim {
-            return true;
-        }
-        let viewers = now.remove(&pos).unwrap_or(0);
-        if viewers != *previous {
-            changes.push((pos, *previous, viewers));
-            *previous = viewers;
-        }
-        viewers > 0
-    });
-    for (pos, viewers) in now {
-        known.insert((dim, pos), viewers);
-        changes.push((pos, 0, viewers));
-    }
-    changes.sort_unstable();
-    changes
-}
-
 pub(super) fn dimension_id(dimension: LevelDimension) -> &'static str {
     match dimension {
         LevelDimension::Overworld => "minecraft:overworld",

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

@@ -3,9 +3,9 @@
 //! Every player in range hears or sees them, as `ServerLevel.playSound` and
 //! `sendParticles` send them. They return false on a client, for a handle of
 //! an earlier open, or for arguments the network can't carry.
-use super::native_hooks::{mod_particles_ok, mod_sound_ok};
 use super::{Dim, Game, creatures::NativeSound, lan_particles::QueuedParticle};
 use horizon_client::mod_api::{LevelRef, ParticleOptions};
+use horizon_client::particles::ParticleType;
 use horizon_world::registry::BlockStateId;
 
 impl Game<'_> {
@@ -85,3 +85,82 @@ impl Game<'_> {
         true
     }
 }
+
+/// Whether `id` is a sound event's id, `namespace:path` as `Identifier`
+/// allows: the namespace of `[a-z0-9_.-]`, the path also with `/`.
+/// Whether a native mod's sound can be sent: a namespaced event, a sound
+/// source, a position inside the world's range and a finite, non-negative
+/// volume and pitch.
+pub(super) fn mod_sound_ok(
+    sound: &str,
+    at: [f64; 3],
+    source: usize,
+    volume: f32,
+    pitch: f32,
+) -> bool {
+    let position_ok = at
+        .into_iter()
+        .all(|v| v.is_finite() && v.abs() <= f64::from(i32::MAX) / 8.0);
+    let gain_ok = volume.is_finite() && volume >= 0.0 && pitch.is_finite() && pitch >= 0.0;
+    sound_id(sound)
+        && source < horizon_client::settings::SOUND_SOURCES.len()
+        && position_ok
+        && gain_ok
+}
+
+/// Whether a native mod's particles can be sent. Block particle types need
+/// a known state (`state_ok`); item, trail and vibration particles aren't
+/// supported by the network dispatch; a mod's own type must be namespaced.
+pub(super) fn mod_particles_ok(
+    options: &ParticleOptions,
+    state: Option<BlockStateId>,
+    state_ok: impl Fn(BlockStateId) -> bool,
+    at: [f64; 3],
+    spread: [f64; 3],
+    speed: f64,
+) -> bool {
+    use ParticleType as T;
+    // A native mod's own type: the name has to be namespaced, and a client
+    // draws it only when its pack has the sprite set.
+    if let Some(name) = &options.mod_particle {
+        let namespaced = name
+            .split_once(':')
+            .is_some_and(|(ns, path)| !ns.is_empty() && !path.is_empty());
+        if !namespaced {
+            return false;
+        }
+    }
+    let supported = match options.ty {
+        T::Block | T::BlockMarker | T::FallingDust | T::DustPillar | T::BlockCrumble => {
+            state.is_some_and(state_ok)
+        }
+        T::Item | T::Trail | T::Vibration => false,
+        T::Geyser | T::GeyserPlume | T::GeyserBase | T::GeyserPoof => options
+            .geyser
+            .is_some_and(|(_, impulse)| impulse.is_finite()),
+        _ => true,
+    };
+    supported
+        && at.into_iter().all(f64::is_finite)
+        && spread
+            .into_iter()
+            .all(|v| v.is_finite() && v.abs() <= f32::MAX as f64)
+        && speed.is_finite()
+        && speed.abs() <= f32::MAX as f64
+        && options.color.into_iter().all(f32::is_finite)
+        && options.to_color.into_iter().all(f32::is_finite)
+        && options.scale.is_finite()
+}
+
+pub(super) fn sound_id(id: &str) -> bool {
+    let Some((namespace, path)) = id.split_once(':') else {
+        return false;
+    };
+    let allowed = |c: char, slash: bool| {
+        c.is_ascii_lowercase() || c.is_ascii_digit() || "_.-".contains(c) || (slash && c == '/')
+    };
+    !namespace.is_empty()
+        && !path.is_empty()
+        && namespace.chars().all(|c| allowed(c, false))
+        && path.chars().all(|c| allowed(c, true))
+}

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

@@ -560,6 +560,34 @@ impl Game<'_> {
     }
 }
 
+/// Sets the viewer counts `known` holds for `dim` to `now` and returns the
+/// changes as `(pos, previous, viewers)`, in position order. A container that
+/// is no longer counted goes to 0 and leaves `known`.
+pub(super) fn viewer_changes(
+    known: &mut std::collections::HashMap<(&'static str, (i32, i32, i32)), u32>,
+    dim: &'static str,
+    mut now: std::collections::HashMap<(i32, i32, i32), u32>,
+) -> Vec<((i32, i32, i32), u32, u32)> {
+    let mut changes = Vec::new();
+    known.retain(|&(d, pos), previous| {
+        if d != dim {
+            return true;
+        }
+        let viewers = now.remove(&pos).unwrap_or(0);
+        if viewers != *previous {
+            changes.push((pos, *previous, viewers));
+            *previous = viewers;
+        }
+        viewers > 0
+    });
+    for (pos, viewers) in now {
+        known.insert((dim, pos), viewers);
+        changes.push((pos, 0, viewers));
+    }
+    changes.sort_unstable();
+    changes
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

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

@@ -208,6 +208,9 @@ fn not_drawn(m: &Manifest, switch: bool) -> Option<String> {
                 .into(),
         );
     }
+    if m.entity.is_some() {
+        return Some("the [entity] stage isn't drawn yet: leave it out".into());
+    }
     (m.api != Api::V0_1 && !switch).then(|| {
         format!(
             "it is written for shader API {}, which is experimental and drawn only under \
@@ -359,6 +362,8 @@ mod tests {
                 why.contains("primaries = \"bt2020\" isn't served yet"),
                 "{why}"
             );
+            let why = not_drawn(&manifest("0.2", "[entity]\nfile = \"e.wgsl\"\n"), switch);
+            assert!(why.unwrap().contains("[entity] stage isn't drawn yet"));
             let named = manifest("0.2", "[frame]\nprimaries = \"bt709\"\n");
             assert_eq!(not_drawn(&named, true), None);
         }

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

@@ -13,6 +13,7 @@ use super::entity::{Entity as _, entity_lists_of, for_each_entity, with_entity};
 use super::{Dim, Game, Result, Screen, level_flags};
 use horizon_client::fast_hash::FxHashMap;
 use horizon_client::nether_portal::{ENTITY_DELAY, PortalState};
+use horizon_client::world::PendingEntity;
 use horizon_core::{
     geometry::{Aabb, Axis, Vec3},
     position::BlockPos,
@@ -74,10 +75,22 @@ impl Plan {
 /// An entity on its way to a dimension that isn't loaded.
 #[derive(Clone, Debug)]
 struct Arrival {
+    /// Teleport-only state; deliberately absent from arrival_tag.
+    tnt_used_portal: bool,
     plan: Plan,
     tag: Tag,
 }
 
+impl Arrival {
+    fn new(plan: Plan, tag: Tag, tnt_used_portal: bool) -> Self {
+        Self {
+            plan,
+            tag,
+            tnt_used_portal,
+        }
+    }
+}
+
 /// The nether portal state of the world (`Game::portals`).
 #[derive(Default)]
 pub(super) struct Portals {
@@ -257,6 +270,7 @@ fn arrival_from_tag(a: &Tag) -> Option<Arrival> {
         return None;
     };
     Some(Arrival {
+        tnt_used_portal: false,
         plan: Plan {
             dim,
             approximate: BlockPos::new(x, y, z),
@@ -531,6 +545,7 @@ impl Game<'_> {
             self.tickets.add_portal(chunk);
         }
     }
+
     /// `NetherPortalBlock.createDimensionTransition`: the arrival position
     /// and the yaw turned by.
     pub(super) fn arrival(&self, plan: &Plan, exit: FoundRectangle) -> (Vec3, f32) {
@@ -1098,7 +1113,7 @@ impl Game<'_> {
             );
             self.remove_dropped(i);
             self.detach_entity(id);
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals.arrivals.push(Arrival::new(plan, tag, false));
             self.portals.dirty = true;
         } else if let Some(i) = self.tnts.iter().position(|t| t.id == id) {
             let t = &self.tnts[i];
@@ -1106,10 +1121,13 @@ impl Game<'_> {
             if !self.may_enter(plan.dim) {
                 return;
             }
+            self.tnts[i].used_portal = true;
             let tag = self.tnt_nbt(i);
-            self.tnts.remove(i);
+            let transferred = self.tnts.remove(i);
             self.forget_entity(id);
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals
+                .arrivals
+                .push(Arrival::new(plan, tag, transferred.used_portal));
             self.portals.dirty = true;
         } else if let Some(i) = self.tridents.iter().position(|t| t.id == id) {
             let plan = self.entity_plan(entry, self.tridents[i].position, 0.5, 0.5, false);
@@ -1121,7 +1139,7 @@ impl Game<'_> {
                 self.tridents[i].to_nbt(uuid, self.pack.assets.registry, self.persist_raw(id));
             self.tridents.remove(i);
             self.forget_entity(id);
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals.arrivals.push(Arrival::new(plan, tag, false));
             self.portals.dirty = true;
         } else if let Some(i) = self.rockets.iter().position(|r| r.id == id) {
             let plan = self.entity_plan(entry, self.rockets[i].position, 0.25, 0.25, false);
@@ -1132,7 +1150,7 @@ impl Game<'_> {
             let tag = self.rockets[i].to_nbt(uuid, self.level.player_uuid, self.persist_raw(id));
             self.rockets.remove(i);
             self.forget_entity(id);
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals.arrivals.push(Arrival::new(plan, tag, false));
             self.portals.dirty = true;
         } else if let Some(i) = self.orbs.iter().position(|o| o.id == id) {
             let plan = self.entity_plan(entry, self.orbs[i].position, 0.5, 0.5, false);
@@ -1143,7 +1161,7 @@ impl Game<'_> {
             let tag = horizon_client::entity_nbt::orb_to_nbt(&self.orbs[i], uuid);
             self.orbs.remove(i);
             self.forget_entity(id);
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals.arrivals.push(Arrival::new(plan, tag, false));
             self.portals.dirty = true;
         } else if let Some(i) = self.mobs.iter().position(|m| m.id == id) {
             let m = &self.mobs[i];
@@ -1162,7 +1180,7 @@ impl Game<'_> {
             for g in gone {
                 self.detach_entity(g);
             }
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals.arrivals.push(Arrival::new(plan, tag, false));
             self.portals.dirty = true;
         } else if let Some(i) = self.boats.iter().position(|b| b.id == id) {
             let b = &self.boats[i];
@@ -1182,7 +1200,7 @@ impl Game<'_> {
             }
             self.boats.remove(i);
             self.detach_entity(id);
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals.arrivals.push(Arrival::new(plan, tag, false));
             self.portals.dirty = true;
         } else if let Some(i) = self.carts.iter().position(|c| c.id == id) {
             let c = &self.carts[i];
@@ -1213,7 +1231,7 @@ impl Game<'_> {
             }
             self.carts.remove(i);
             self.detach_entity(id);
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals.arrivals.push(Arrival::new(plan, tag, false));
             self.portals.dirty = true;
         } else if let Some(i) = self
             .creatures
@@ -1248,7 +1266,7 @@ impl Game<'_> {
             };
             self.creatures.projectiles.remove(i);
             self.forget_entity(id);
-            self.portals.arrivals.push(Arrival { plan, tag });
+            self.portals.arrivals.push(Arrival::new(plan, tag, false));
             self.portals.dirty = true;
         }
         if self.portals.arrivals.len() > arrivals {
@@ -1323,7 +1341,11 @@ impl Game<'_> {
                 i += 1;
                 continue;
             }
-            let Arrival { plan, mut tag } = self.portals.arrivals.remove(i);
+            let Arrival {
+                plan,
+                mut tag,
+                tnt_used_portal,
+            } = self.portals.arrivals.remove(i);
             self.portals.dirty = true;
             let motion = horizon_client::entity_nbt::motion(&tag);
             let [yaw, pitch] = horizon_client::entity_nbt::rotation(&tag);
@@ -1359,6 +1381,11 @@ impl Game<'_> {
             preserve_arrival_cooldown(&mut tag);
             // ServerLevel.addDuringTeleport: a fresh add, not loaded from disk.
             super::persist::mark_fresh(&mut tag);
+            let tag = if tnt_used_portal {
+                PendingEntity::after_tnt_portal(tag)
+            } else {
+                tag.into()
+            };
             let key = ((at.x.floor() as i32) >> 4, (at.z.floor() as i32) >> 4);
             match self
                 .world
@@ -1423,7 +1450,7 @@ impl Game<'_> {
         if f.id != 0 {
             self.forget_entity(f.id);
         }
-        self.portals.arrivals.push(Arrival { plan, tag });
+        self.portals.arrivals.push(Arrival::new(plan, tag, false));
         self.portals.dirty = true;
         Some(plan.dim)
     }
@@ -1598,6 +1625,20 @@ impl Game<'_> {
 mod tests {
     use super::*;
 
+    #[test]
+    fn portal_transfer_pending_arrival_does_not_save_transient_tnt_immunity() {
+        let arrival = Arrival {
+            plan: Plan::end_portal(Dim::End, BlockPos::new(0, 64, 0), 0.98, 0.98),
+            tag: Tag::compound([("id", Tag::String("minecraft:tnt".into()))]),
+            tnt_used_portal: true,
+        };
+        assert!(
+            !arrival_from_tag(&arrival_tag(&arrival))
+                .unwrap()
+                .tnt_used_portal
+        );
+    }
+
     #[test]
     fn end_portals_lead_to_the_end_spawn_and_back_to_the_world_spawn() {
         let spawn = BlockPos::new(-7, 70, 12);
@@ -1677,6 +1718,7 @@ mod tests {
             let arrival = Arrival {
                 plan: Plan::end_portal(Dim::Overworld, BlockPos::new(0, 64, 0), 1.375, 0.5625),
                 tag,
+                tnt_used_portal: false,
             };
             let restored = arrival_from_tag(&arrival_tag(&arrival)).unwrap();
             let expected = old.filter(|n| *n > 0).unwrap_or(ENTITY_DELAY);
@@ -1692,6 +1734,7 @@ mod tests {
         let tag = Tag::compound([("id", Tag::String("minecraft:cow".into()))]);
         for (from, dim) in [(Dim::Overworld, Dim::End), (Dim::End, Dim::Overworld)] {
             let arrival = Arrival {
+                tnt_used_portal: false,
                 plan: Plan::end_portal(from, BlockPos::new(3, 64, -5), 0.9, 1.4),
                 tag: tag.clone(),
             };
@@ -1703,6 +1746,7 @@ mod tests {
         }
         // Arrivals saved before End portals were Nether portal plans.
         let mut old = arrival_tag(&Arrival {
+            tnt_used_portal: false,
             plan: Plan::end_portal(Dim::End, BlockPos::new(0, 64, 0), 0.25, 0.25),
             tag,
         });

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

@@ -126,6 +126,8 @@ impl Game<'_> {
                 .map(super::native_hooks::mob_kind)
                 .unwrap_or_default();
             self.native_entity_enter_love_mode(id, &kind, self.lan_acting_uuid);
+            // Animal.setInLove: entity event 18, the love hearts.
+            self.mob_event_particles(id, 18);
         }
         self.consume_held();
         if let Some(stack) = dropped {

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

@@ -7,6 +7,7 @@ mod display;
 mod hurt_by_refs;
 
 use super::{FallingBlock, Game};
+use horizon_client::world::EntityLoadReason;
 use horizon_client::{
     Result,
     chunk::Chunk,
@@ -534,7 +535,7 @@ impl Game<'_> {
         let player_uuid = self.level.player_uuid;
         for (key, tags) in loaded {
             let count = tags.len();
-            for mut tag in tags {
+            for (mut tag, reason) in tags.into_iter().map(|pending| pending.into_parts()) {
                 // A world older builds named by the offline profile names the player that
                 // way in its entities too: migrate them as they load, so the next save of
                 // the chunk keeps the account's UUID (`playerdata::migrate_owner`).
@@ -591,7 +592,16 @@ impl Game<'_> {
                 }
                 // Kinds outside `entity_lists!` first, then the listed kinds
                 // (`Entity::load_nbt`), then whatever else is a compound.
-                if let Err(tag) = self.load_unlisted(key, &kind, uuid, tag)
+                let loaded = if reason == EntityLoadReason::TeleportedTnt
+                    && kind == "minecraft:tnt"
+                    && !is_mob
+                {
+                    self.load_tnt_with_portal(tag, uuid, true);
+                    Ok(())
+                } else {
+                    self.load_unlisted(key, &kind, uuid, tag)
+                };
+                if let Err(tag) = loaded
                     && let Err(tag) = self.load_listed(&kind, uuid, player_uuid, tag)
                 {
                     if !kind.is_empty() && entity_nbt::position(&tag).is_some() {
@@ -852,6 +862,9 @@ impl Game<'_> {
     /// `PrimedTnt.readAdditionalSaveData`: its numeric short fuse (80 when absent) and motion.
     // Its Passengers ride it (EntityType.loadEntityRecursive forces them on).
     pub(super) fn load_tnt(&mut self, tag: Tag, uuid: Option<[i32; 4]>) {
+        self.load_tnt_with_portal(tag, uuid, false);
+    }
+    fn load_tnt_with_portal(&mut self, tag: Tag, uuid: Option<[i32; 4]>, used_portal: bool) {
         if uuid.is_some_and(|u| self.target_with_uuid(u).is_some()) {
             return;
         }
@@ -868,6 +881,7 @@ impl Game<'_> {
             // to int before short narrowing; integer tags narrow directly.
             let fuse = tnt_fuse(&tag);
             self.tnts.push(super::tnt::PrimedTnt {
+                used_portal,
                 rotation: [0.0, 0.0],
                 join: Default::default(),
                 no_gravity: entity_nbt::flag(&tag, "NoGravity"),
@@ -1370,7 +1384,7 @@ impl Game<'_> {
         {
             entity_nbt::fill_common_defaults(&mut tag);
         }
-        tag
+        with_raw(tag, None) // Entity.saveWithoutId's flags, as booleans.
     }
     /// The root of a stack of riders (`Entity.getRootVehicle`).
     fn mob_root(&self, mut i: usize) -> usize {
@@ -1500,7 +1514,7 @@ impl Game<'_> {
                 (at.z.floor() as i32).div_euclid(16),
             );
             self.persist.restored.insert(root_uuid);
-            self.world.loaded_entities.push((key, vec![tag]));
+            self.world.queue_entity_nbt(key, vec![tag]);
             self.spawn_loaded_entities();
         }
         self.persist.restored.insert(uuid);
@@ -2998,7 +3012,7 @@ mod tests {
         }
         // The level is a server's, whose attachments a mod reaches.
         game.options.dedicated = Some(Vec::new());
-        game.world.loaded_entities.push(((0, 0), tags));
+        game.world.queue_entity_nbt((0, 0), tags);
         game.spawn_loaded_entities();
         let saved = game.entity_chunks(&HashSet::from([(0, 0)]), false);
         let saved: Vec<&Tag> = saved.iter().flat_map(|(_, tags)| tags).collect();
@@ -3088,7 +3102,7 @@ mod tests {
                 .filter(|c| c.potion.is_some())
                 .count()
         };
-        game.world.loaded_entities.push(((0, 0), vec![cloud]));
+        game.world.queue_entity_nbt((0, 0), vec![cloud]);
         game.spawn_loaded_entities();
         assert_eq!(clouds(&game), 1, "the cloud loads");
         assert_eq!(game.breath_clouds[0].motion, [0.6, 0.0, 0.0]);
@@ -3100,7 +3114,7 @@ mod tests {
             Vec3::new(0.6, 0.0, 0.0)
         );
         assert_eq!(clouds(&game), 0, "and takes it out of the level");
-        game.world.loaded_entities.push(((0, 0), written));
+        game.world.queue_entity_nbt((0, 0), written);
         game.spawn_loaded_entities();
         assert_eq!(clouds(&game), 1, "loading the chunk again gives one cloud");
         assert_eq!(game.breath_clouds[0].motion, [0.6, 0.0, 0.0]);
@@ -4258,6 +4272,7 @@ mod attribute_instance_save_tests {
         assert!(game.run_command("forceload add 0 0"));
         game.player = Some(PlayerMotion::new(game.motion, Vec3::new(2.5, 200.0, 2.5)).unwrap());
         game.creative = true;
+        game.load_ticking_neighbourhood(0, 0);
         test(&mut game);
     }
     fn mob(game: &Game<'_>, n: i32) -> usize {
@@ -5276,6 +5291,7 @@ mod h262_enderman_absolute_anger_tests {
             game.run_command("summon pig 13.5 200 2.5 {UUID:[I;262,0,0,99],NoAI:1b,NoGravity:1b}")
         );
         game.world.random.set_seed(262);
+        game.load_ticking_neighbourhood(0, 0);
         test(&mut game);
     }
     fn load(game: &mut Game<'_>, n: i32, end: Option<i64>) -> (u32, usize) {
@@ -5511,6 +5527,7 @@ mod sulfur_body_attribute_tests {
         assert!(game.run_command("scoreboard objectives add h192 dummy"));
         game.player = Some(PlayerMotion::new(game.motion, Vec3::new(2.5, 200.0, 2.5)).unwrap());
         game.creative = true;
+        game.load_ticking_neighbourhood(0, 0);
         test(&mut game);
     }
     /// `/attribute <cube> <attribute> get 1000`, read back through a score.
@@ -5536,9 +5553,9 @@ mod sulfur_body_attribute_tests {
                 (2, ""),
             ] {
                 assert!(game.run_command(&format!(
-                    "summon minecraft:sulfur_cube {}.5 200 4.5 {{UUID:[I;192,0,0,{n}],NoAI:1b,NoGravity:1b,Silent:1b,PersistenceRequired:1b,Size:1{body}}}",
-                    3 * n
-                )));
+                        "summon minecraft:sulfur_cube {}.5 200 4.5 {{UUID:[I;192,0,0,{n}],NoAI:1b,NoGravity:1b,Silent:1b,PersistenceRequired:1b,Size:1{body}}}",
+                        3 * n
+                    )));
             }
             let attrs = [
                 "knockback_resistance",
@@ -5582,8 +5599,8 @@ mod sulfur_body_attribute_tests {
     fn a_bodiless_cube_keeps_its_command_knockback_resistance_effect() {
         with_game(|game| {
             assert!(game.run_command(
-                "summon minecraft:sulfur_cube 4.5 200 8.5 {UUID:[I;192,0,0,9],NoAI:1b,NoGravity:1b,Silent:1b,PersistenceRequired:1b,Size:1}"
-            ));
+                    "summon minecraft:sulfur_cube 4.5 200 8.5 {UUID:[I;192,0,0,9],NoAI:1b,NoGravity:1b,Silent:1b,PersistenceRequired:1b,Size:1}"
+                ));
             let sel = "@e[type=minecraft:sulfur_cube,nbt={UUID:[I;192,0,0,9]},limit=1]";
             let cached = |game: &Game<'_>| {
                 let m = game
@@ -5650,9 +5667,9 @@ mod sulfur_body_attribute_tests {
                 (11, ",equipment:{body:{id:\"minecraft:oak_planks\"}}"),
             ] {
                 assert!(game.run_command(&format!(
-                    "summon minecraft:sulfur_cube {}.5 200 8.5 {{UUID:[I;192,0,0,{n}],NoAI:1b,NoGravity:1b,Silent:1b,PersistenceRequired:1b,Size:1{body}}}",
-                    n - 8
-                )));
+                        "summon minecraft:sulfur_cube {}.5 200 8.5 {{UUID:[I;192,0,0,{n}],NoAI:1b,NoGravity:1b,Silent:1b,PersistenceRequired:1b,Size:1{body}}}",
+                        n - 8
+                    )));
             }
             game.tick_world(true).unwrap();
             let cached = |game: &Game<'_>, n: i32| {
@@ -5765,6 +5782,7 @@ mod summoned_knot_tests {
             game.run_command("summon pig 13.5 200 2.5 {UUID:[I;129,0,0,99],NoAI:1b,NoGravity:1b}")
         );
         game.world.random.set_seed(129);
+        game.load_ticking_neighbourhood(0, 0);
         test(&mut game);
     }
     fn knot_id(game: &Game<'_>, n: i32) -> u32 {
@@ -5895,12 +5913,8 @@ mod summoned_knot_tests {
     #[ignore = "prepared resources; negative fractional registered position"]
     fn negative_fractional_knot_position_uses_floor_before_centering() {
         with_game(|game| {
-            game.world
-                .chunks
-                .insert((-1, -1), Arc::new(Chunk::empty(-1, -1)));
-            game.block_ticks
-                .add_empty_chunk(ChunkPos::new(-1, -1))
-                .unwrap();
+            // Chunk (-1, -1) is already loaded by the fixture's neighbourhood.
+            assert!(game.world.chunks.contains_key(&(-1, -1)));
             assert!(game.run_command("setblock -2 199 -3 stone strict"));
             assert!(game.run_command("setblock -2 200 -3 oak_fence strict"));
             assert!(game.run_command("summon leash_knot -1.2 200.8 -2.1 {UUID:[I;129,0,0,5]}"));
@@ -6127,7 +6141,9 @@ mod camel_pose_saved_tests {
             .into_iter()
             .flat_map(|(_, tags)| tags)
             .collect();
-        game.world.loaded_entities.push(((0, 0), written));
+        game.world
+            .loaded_entities
+            .push(((0, 0), written.into_iter().map(Into::into).collect()));
         game.spawn_loaded_entities();
         for step in 0..8 {
             for number in 1..=cases.len() as i32 {

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

@@ -1498,6 +1498,7 @@ mod h255_mob_piston_ground_tests {
                     .unwrap();
             }
         }
+        game.load_ticking_neighbourhood(0, 0);
         game.player = Some(PlayerMotion::new(game.motion, Vec3::new(2.5, 200.0, 2.5)).unwrap());
         game.creative = true;
         assert!(game.run_command("fill 0 199 0 31 199 31 stone"));

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

@@ -112,19 +112,21 @@ impl Game<'_> {
         equipped.push((self.inventory[self.selected].as_ref(), "mainhand"));
         equipped.push((self.offhand.as_ref(), "offhand"));
         for (stack, slot) in equipped {
+            // ItemStack.forEachModifier: the stack's own ATTRIBUTE_MODIFIERS
+            // (its item's unless a command or a mod replaced them, #14641).
             let Some(stack) = stack else {
                 continue;
             };
-            let modifiers = world_items!(self).attribute_modifiers(stack);
-            for (attribute, id, amount, op, group) in &modifiers {
-                if !equipment_modifier_applies(group, slot) {
+            for (attribute, id, amount, op, group) in world_items!(self).attribute_modifiers(stack)
+            {
+                if !equipment_modifier_applies(&group, slot) {
                     continue;
                 }
                 if player
-                    .set_modifier_unclamped(attribute, id, *amount, op, true)
+                    .set_modifier_unclamped(&attribute, &id, amount, &op, true)
                     .is_ok()
                 {
-                    self.applied_modifiers.push((attribute.clone(), id.clone()));
+                    self.applied_modifiers.push((attribute, id));
                 }
             }
         }

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

@@ -35,6 +35,7 @@ fn mobs_past_the_simulation_distance_neither_enter_portals_nor_cool_down() {
         game.world
             .chunks
             .insert((cx, 0), Arc::new(Chunk::empty(cx, 0)));
+        game.load_ticking_neighbourhood(cx, 0);
         for z in [8, 12] {
             game.world.set(x, 63, z, stone).unwrap();
         }

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

@@ -385,31 +385,21 @@ impl Game<'_> {
                 .play("minecraft:entity.silverfish.hurt", Some(at), 1.0, 1.0);
         }
     }
-    /// A splash potion, lingering potion or experience bottle in flight (the
-    /// player's throws and dispensers both end up here).
-    pub(super) fn launch_thrown(
-        &mut self,
-        stack: ItemStack,
-        position: Vec3,
-        velocity: Vec3,
-        owner: Option<Text>,
-    ) {
-        let id = self.take_entity_id();
-        self.potions.thrown.push(ThrownPotion {
-            id,
-            stack,
-            previous: position,
-            position,
-            velocity,
-            age: 0,
-            thrower: owner.is_some().then_some(Who::Player),
-            guest: self.lan_acting.filter(|_| owner.is_some()),
-            owner,
-            left_owner: false,
-            last_deflected_by: None,
-            random: LegacyRandom::new(i64::from(id)),
-        });
-    }
+}
+/// A splash potion, lingering potion or experience bottle about to fly (the
+/// player's throws and dispensers both make one): `ThrownSplashPotion`,
+/// `ThrownLingeringPotion` or `ThrownExperienceBottle`, which
+/// `level.addFreshEntity` makes a level entity like a summoned one, so
+/// selectors and `/data` find it (#13201).
+pub(super) fn thrown_projectile(stack: ItemStack, position: Vec3, by_player: bool) -> Projectile {
+    let kind = match &*stack.item {
+        "minecraft:experience_bottle" => ProjectileKind::ExperienceBottle,
+        item => {
+            let lingering = item == "minecraft:lingering_potion";
+            ProjectileKind::Potion(Box::new(stack), lingering)
+        }
+    };
+    Projectile::new(kind, position, by_player.then_some(Who::Player))
 }
 /// What a player's body was last given for its effects and enchantments:
 /// a guest keeps their own while the host's are in `PotionState`.
@@ -586,43 +576,21 @@ impl Game<'_> {
                     _ => ("minecraft:entity.lingering_potion.throw", 0.5),
                 };
                 self.audio.play(sound, Some(eye), 0.5, pitch);
-                // Projectile.shootFromRotation(xRot, yRot, -20, 0.5, 1.0).
-                let (yaw, pitch) = (self.yaw.to_radians(), self.pitch.to_radians());
-                let dir = [
-                    -yaw.sin() * pitch.cos(),
-                    -(self.pitch - 20.0).to_radians().sin(),
-                    yaw.cos() * pitch.cos(),
-                ];
-                let l = dir
-                    .iter()
-                    .map(|c| f64::from(*c).powi(2))
-                    .sum::<f64>()
-                    .sqrt()
-                    .max(1e-9);
-                // getMovementToShoot: normalize, add triangle(0, 0.0172275 * uncertainty), scale.
-                let r = &mut self.world.random;
-                let mut jitter = || r.triangle(0.0, 0.0172275);
-                let v = Vec3::new(
-                    (f64::from(dir[0]) / l + jitter()) * power,
-                    (f64::from(dir[1]) / l + jitter()) * power,
-                    (f64::from(dir[2]) / l + jitter()) * power,
-                );
-                let pv = self.known_player_movement();
+                // Projectile.shootFromRotation(xRot, yRot, -20, power, 1.0), with
+                // what the thrower last moved (getKnownMovement).
+                let velocity = self.known_player_movement();
                 let on_ground = self.player.as_ref().is_some_and(|p| p.ground.on_ground);
-                let v = Vec3::new(
-                    v.x + pv.x,
-                    v.y + if on_ground { 0.0 } else { pv.y },
-                    v.z + pv.z,
-                );
-                self.launch_thrown(
-                    ItemStack {
-                        count: 1,
-                        ..stack.clone()
-                    },
-                    Vec3::new(eye[0], eye[1] - 0.1, eye[2]),
-                    v,
-                    Some(self.player_display_text()),
+                let one = ItemStack {
+                    count: 1,
+                    ..stack.clone()
+                };
+                let mut shot =
+                    thrown_projectile(one, Vec3::new(eye[0], eye[1] - 0.1, eye[2]), true);
+                shot.shoot_from_rotation(
+                    self.pitch, self.yaw, -20.0, power, 1.0, velocity, on_ground,
                 );
+                shot.guest = self.lan_acting;
+                self.add_projectile(shot);
                 // ThrowablePotionItem.use / ExperienceBottleItem.use: awardStat(ITEM_USED).
                 self.award_stat("used", &stack.item, 1);
                 self.swing_arm();
@@ -2667,6 +2635,7 @@ mod mob_absorption_max_tests {
         game.player = Some(PlayerMotion::new(game.motion, Vec3::new(2.5, 200.0, 2.5)).unwrap());
         game.creative = true;
         assert!(game.run_command("scoreboard objectives add h203 dummy"));
+        game.load_ticking_neighbourhood(0, 0);
         test(&mut game);
     }
     fn pig(game: &Game<'_>, n: i32) -> usize {
@@ -2836,6 +2805,7 @@ mod mob_health_boost_tests {
         assert!(game.run_command("forceload add 0 0"));
         game.player = Some(PlayerMotion::new(game.motion, Vec3::new(2.5, 200.0, 2.5)).unwrap());
         game.creative = true;
+        game.load_ticking_neighbourhood(0, 0);
         test(&mut game);
     }
     fn pig(game: &Game<'_>, n: i32) -> usize {
@@ -3081,6 +3051,7 @@ mod depleted_absorption_tests {
         assert!(game.run_command("forceload add 0 0"));
         game.player = Some(PlayerMotion::new(game.motion, Vec3::new(2.5, 200.0, 2.5)).unwrap());
         game.creative = true;
+        game.load_ticking_neighbourhood(0, 0);
         test(&mut game);
     }
     /// The mob in the level with UUID word `n`.

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

@@ -3029,11 +3029,12 @@ impl Game<'_> {
                 d.on_ground = on_ground;
                 return;
             }
-            if let Some(f) = self.falling.iter_mut().find(|f| f.id == id as u32) {
+            // A newly spawned block or TNT is at the back of its list.
+            if let Some(f) = self.falling.iter_mut().rev().find(|f| f.id == id as u32) {
                 f.position = at;
                 return;
             }
-            if let Some(t) = self.tnts.iter_mut().find(|t| t.id == id as u32) {
+            if let Some(t) = self.tnts.iter_mut().rev().find(|t| t.id == id as u32) {
                 t.position = at;
                 t.on_ground = on_ground;
                 return;
@@ -3409,20 +3410,7 @@ impl Game<'_> {
                 self.capture(true);
             }
             C::PlayerPosition(p) => self.remote_teleport(&p)?,
-            C::PlayerRotation(p) => {
-                self.yaw = if p.relative_yaw {
-                    self.yaw + p.yaw
-                } else {
-                    p.yaw
-                };
-                self.pitch = (if p.relative_pitch {
-                    self.pitch + p.pitch
-                } else {
-                    p.pitch
-                })
-                .clamp(-90.0, 90.0);
-                self.snap_player_model_pitch();
-            }
+            C::PlayerRotation(p) => self.remote_rotation(&p),
             C::PlayerLookAt(p) => self.remote_look_at(&p),
             // ClientCommonPacketListenerImpl.handlePostEffects.
             C::PostEffects(p) => self.post_effects = p.effects,
@@ -3576,6 +3564,7 @@ impl Game<'_> {
                     p.id as u32,
                     horizon_client::lan::playerdata::uuid_ints(p.uuid),
                 );
+                let replace = self.tracks_remote_entity(p.id);
                 self.spawn_entity(p.id, &kind, p.position, rotation);
                 if let Some(r) = self.remote.as_mut() {
                     r.cart_lerps.remove(&p.id);
@@ -3588,14 +3577,7 @@ impl Game<'_> {
                     (rotation[0], rotation[1]),
                     p.data,
                 ) {
-                    self.spawn_remote_projectile(
-                        p.id,
-                        &kind,
-                        p.position,
-                        (rotation[0], rotation[1]),
-                        p.velocity,
-                        p.data,
-                    );
+                    self.spawn_added_projectile(&p, &kind, (rotation[0], rotation[1]), replace);
                 }
                 // Entity.recreateFromPacket: objects must exist before applying motion.
                 self.remote_motion(p.id, p.velocity);
@@ -5898,14 +5880,16 @@ impl Game<'_> {
     fn remote_motion(&mut self, id: i32, velocity: [f64; 3]) {
         self.remote_dragon_motion(id, velocity);
         let v = Vec3::new(velocity[0], velocity[1], velocity[2]);
+        // `falling` and `tnts` are searched from the back: AddEntity calls this right after
+        // appending the block or TNT, so a spawn doesn't walk the whole list.
         if let Some(m) = self.mob_index.get_mut(&mut self.mobs, id as u32) {
             // Squid.aiStep derives its body pitch and roll from network motion.
             m.velocity = v;
         } else if let Some(d) = self.dropped.iter_mut().find(|d| d.id == id as u32) {
             d.velocity = v;
-        } else if let Some(f) = self.falling.iter_mut().find(|f| f.id == id as u32) {
+        } else if let Some(f) = self.falling.iter_mut().rev().find(|f| f.id == id as u32) {
             f.velocity = v;
-        } else if let Some(t) = self.tnts.iter_mut().find(|t| t.id == id as u32) {
+        } else if let Some(t) = self.tnts.iter_mut().rev().find(|t| t.id == id as u32) {
             t.velocity = v;
         } else if let Some(o) = self.orbs.iter_mut().find(|o| o.id == id as u32) {
             o.velocity = v;

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

@@ -34,6 +34,29 @@ impl Game<'_> {
     pub(in crate::game) fn remote_walking_speed(&self) -> f32 {
         walking_speed(self.remote.as_ref().and_then(|r| r.abilities.as_ref()))
     }
+
+    /// ClientPacketListener.handleRotatePlayer: the server's yaw and pitch, each added to the
+    /// current one when its bit says relative, then sent back as a `Rot` move with both
+    /// flags false.
+    pub(super) fn remote_rotation(&mut self, p: &play::PlayerRotation) {
+        self.yaw = if p.relative_yaw {
+            self.yaw + p.yaw
+        } else {
+            p.yaw
+        };
+        self.pitch = (if p.relative_pitch {
+            self.pitch + p.pitch
+        } else {
+            p.pitch
+        })
+        .clamp(-90.0, 90.0);
+        self.snap_player_model_pitch();
+        self.send(S::MovePlayerRot(play::MovePlayerRot {
+            yaw: self.yaw,
+            pitch: self.pitch,
+            flags: 0,
+        }));
+    }
 }
 
 #[cfg(test)]

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

@@ -132,6 +132,14 @@ impl Game<'_> {
                     .unwrap_or_default();
                 nautilus_takes(nautilus::is_food(m, item, &taming), m.extra.tame, baby)
             }
+            // Dolphin.mobInteract: a #minecraft:fishes item is SUCCESS on both
+            // sides (the server feeds it), so the client swings and keeps the fish.
+            Species::Dolphin => self
+                .res
+                .items()
+                .item_tags
+                .get("minecraft:fishes")
+                .is_some_and(|t| t.contains(item)),
             // IronGolem.mobInteract.
             Species::IronGolem => iron_golem_takes(item, m.health, m.attrs.max_health),
             // CopperGolem.mobInteract.
@@ -254,7 +262,15 @@ fn copper_golem_takes(item: &str, holding: bool, shearable: bool) -> bool {
 /// `handleEating` gates both on `isBaby() && !isAgeLocked()` — a locked baby
 /// does not grow, and the particle goes with the growth.
 pub(super) fn ages_on_food(m: &Mob, item: &str) -> bool {
-    if !m.is_baby() || m.extra.age_locked || item.is_empty() {
+    if m.extra.age_locked || item.is_empty() {
+        return false;
+    }
+    // Tadpole.feed draws the same particle on both sides; a tadpole is never
+    // `isBaby`, its age counts up to the frog.
+    if m.species() == Species::Tadpole {
+        return m.kind.food.iter().any(|f| f.as_str() == item);
+    }
+    if !m.is_baby() {
         return false;
     }
     match m.species() {
@@ -494,4 +510,18 @@ mod tests {
             assert!(!ages_on_food(&camel, "minecraft:cactus"), "locked camel");
         }
     }
+
+    /// `Tadpole.feed` draws its particle on the client too, though a tadpole
+    /// is never a baby; an age-locked one is not fed (#8554).
+    #[test]
+    fn a_tadpole_fed_a_slime_ball_draws_happy_villager() {
+        let Some(mut tadpole) = mob("minecraft:tadpole") else {
+            return;
+        };
+        assert!(!tadpole.is_baby());
+        assert!(ages_on_food(&tadpole, "minecraft:slime_ball"));
+        assert!(!ages_on_food(&tadpole, "minecraft:wheat"), "not frog food");
+        tadpole.extra.age_locked = true;
+        assert!(!ages_on_food(&tadpole, "minecraft:slime_ball"), "locked");
+    }
 }

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

@@ -316,15 +316,58 @@ impl Game<'_> {
         rotation: (f32, f32),
         velocity: [f64; 3],
         data: i32,
+    ) -> bool {
+        self.remove_remote_projectile(id as u32);
+        self.spawn_remote_projectile_inner(id, kind, position, rotation, velocity, data)
+    }
+
+    /// Whether the client tracks `id` already: asked by `AddEntity` before it tracks the new one.
+    pub(super) fn tracks_remote_entity(&self, id: i32) -> bool {
+        self.remote
+            .as_ref()
+            .is_some_and(|r| r.tracked_entity(id).is_some())
+    }
+
+    /// `AddEntity`'s `spawn_remote_projectile`. Only an id the client already tracked (`replace`)
+    /// can still be in `falling` or `tnts`, so a new id skips those passes; the crystals and the
+    /// small lists are filtered every time, since the client adds to some of those itself.
+    pub(super) fn spawn_added_projectile(
+        &mut self,
+        p: &horizon_protocol::packets::play::AddEntity,
+        kind: &str,
+        rotation: (f32, f32),
+        replace: bool,
+    ) {
+        if replace {
+            self.spawn_remote_projectile(p.id, kind, p.position, rotation, p.velocity, p.data);
+        } else {
+            self.crystals.retain(|c| c.id != p.id as u32);
+            self.remove_remote_small_projectiles(p.id as u32);
+            self.spawn_remote_projectile_inner(
+                p.id, kind, p.position, rotation, p.velocity, p.data,
+            );
+        }
+    }
+
+    /// `spawn_remote_projectile` without first removing an entity under the same id: for
+    /// `AddEntity` of an id the client does not track yet, which no list holds.
+    pub(super) fn spawn_remote_projectile_inner(
+        &mut self,
+        id: i32,
+        kind: &str,
+        position: [f64; 3],
+        rotation: (f32, f32),
+        velocity: [f64; 3],
+        data: i32,
     ) -> bool {
         let id = id as u32;
         let at = Vec3::new(position[0], position[1], position[2]);
         let velocity = Vec3::new(velocity[0], velocity[1], velocity[2]);
         let (yaw, pitch) = rotation;
-        self.remove_remote_projectile(id);
         match kind {
             "minecraft:evoker_fangs" => self.insert_fangs(id, position, yaw, 0, 0),
             "minecraft:tnt" => self.tnts.push(super::tnt::PrimedTnt {
+                used_portal: false,
                 rotation: [0.0, 0.0],
                 join: Default::default(),
                 no_gravity: false,
@@ -400,14 +443,8 @@ impl Game<'_> {
                     .next_int_bound(100_000)
                     .unwrap_or(0);
                 let time = super::dragon::Crystal::start_time(at, drawn, self.clock.still());
-                self.crystals.push(super::dragon::Crystal {
-                    id,
-                    position: at,
-                    show_bottom: true,
-                    time,
-                    beam: None,
-                    invulnerable: false,
-                });
+                self.crystals
+                    .push(super::dragon::Crystal::new(id, at, true, time));
             }
             _ => {
                 let Some(k) = projectile_kind(kind) else {

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

@@ -183,6 +183,93 @@ mod tests {
         assert_eq!(game.falling.iter().map(|e| e.id).collect::<Vec<_>>(), [45]);
     }
 
+    #[test]
+    #[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES and scratch homes/cwd"]
+    fn add_entity_replaces_falling_block_without_removing_other_ids() {
+        use crate::game::{
+            Audio, Game, Options, Progress, Settings, execution_role::ExecutionRole, load_resources,
+        };
+        use horizon_protocol::packets::play::{self, Clientbound as C};
+
+        let root = std::path::PathBuf::from(std::env::var_os("HORIZON_TEST_RESOURCES").unwrap());
+        let settings = Settings::default();
+        let loaded = load_resources(
+            root.clone(),
+            None,
+            &root,
+            &settings,
+            std::time::Instant::now(),
+            false,
+            true,
+            &Progress::new(),
+            &mut |_, _| unreachable!(),
+        )
+        .unwrap();
+        let mut options = Options::parse(std::iter::empty()).unwrap().unwrap();
+        options.resources = root.clone();
+        options.execution_role = ExecutionRole::Client;
+        let mut game = Game::new(
+            &loaded.resources,
+            loaded.pack,
+            loaded.gui.unwrap(),
+            options,
+            settings,
+            Audio::silent(&root),
+            None,
+        )
+        .unwrap();
+        let (client, _server) = horizon_protocol::connection::Pipe::pair();
+        game.connect_local(client, "SpawnTest").unwrap();
+        let kind = game
+            .remote
+            .as_ref()
+            .unwrap()
+            .builtin
+            .get("minecraft:entity_type")
+            .unwrap()
+            .id("minecraft:falling_block")
+            .unwrap();
+        for (id, position) in [
+            (40, [1.0, 64.0, 2.0]),
+            (41, [3.0, 65.0, 4.0]),
+            (40, [5.0, 66.0, 6.0]),
+            (42, [7.0, 67.0, 8.0]),
+        ] {
+            game.handle_packet(C::AddEntity(play::AddEntity {
+                id,
+                uuid: id as u128,
+                kind,
+                position,
+                velocity: [0.0, -0.1, 0.0],
+                pitch: 0,
+                yaw: 0,
+                head_yaw: 0,
+                data: 0,
+            }))
+            .unwrap();
+            assert_eq!(game.falling.iter().filter(|f| f.id == id as u32).count(), 1);
+            let block = game.falling.iter().find(|f| f.id == id as u32).unwrap();
+            assert_eq!(
+                [block.position.x, block.position.y, block.position.z],
+                position
+            );
+            assert_eq!(block.velocity.y, -0.1);
+        }
+        let blocks: Vec<_> = game
+            .falling
+            .iter()
+            .map(|f| (f.id, [f.position.x, f.position.y, f.position.z]))
+            .collect();
+        assert_eq!(
+            blocks,
+            [
+                (41, [3.0, 65.0, 4.0]),
+                (40, [5.0, 66.0, 6.0]),
+                (42, [7.0, 67.0, 8.0]),
+            ]
+        );
+    }
+
     #[test]
     #[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES and scratch homes/cwd"]
     fn remove_entities_filters_mixed_entity_lists() {

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

@@ -67,6 +67,16 @@ impl Game<'_> {
             menu.set_slot(env, i, stack);
             Some(true)
         });
+        if internal == super::stations::INPUT
+            && let Some(s) = self
+                .station
+                .as_mut()
+                .filter(|s| s.kind == Kind::Stonecutter)
+        {
+            // The client menu's `Slot.set` on the input runs the screen's
+            // listener (`StonecutterMenu.container.setChanged`).
+            s.stonecutter_changed();
+        }
         // AnvilScreen.slotChanged: the box shows the new input's name, which
         // its responder sends.
         self.remote_anvil_rename();

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

@@ -57,6 +57,9 @@ fn game() -> Game<'static> {
             .add_empty_chunk(ChunkPos::new(x, 0))
             .unwrap();
     }
+    for x in 0..9 {
+        game.load_ticking_neighbourhood(x, 0);
+    }
     for command in [
         "forceload add 0 0 143 15",
         "tick freeze",

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

@@ -484,6 +484,37 @@ impl Game<'_> {
             .unwrap_or(self.ui.registries.permission)
             > 0
     }
+    /// `EntityType.createDefaultStackConfig` on an entity an item made (a
+    /// vehicle, a hanging entity, an armor stand): the item's custom name and
+    /// custom data (`applyComponentsFromItemStack`:
+    /// `Entity.applyImplicitComponent`'s two, saved as `CustomName` and
+    /// `data`), then its `minecraft:entity_data` merged over the entity's own
+    /// compound and loaded (`updateCustomEntityTag`) when it names this type.
+    /// An op-only type (command block and spawner minecarts) takes it from an
+    /// op player only, never from a dispenser (`by_player` false).
+    pub(super) fn apply_item_stack_config(
+        &mut self,
+        target: super::commands::Target,
+        kind: &str,
+        stack: &horizon_client::items::ItemStack,
+        by_player: bool,
+    ) {
+        let op = by_player && self.acting_player_is_op();
+        let configures = stack
+            .data()
+            .is_some_and(|d| d.custom_name.is_some() || d.other("minecraft:custom_data").is_some())
+            || horizon_client::block_entity_item::spawn_egg_entity_data(stack, kind, op).is_some();
+        if !configures {
+            return;
+        }
+        let Some(own) = self.entity_nbt(target) else {
+            return;
+        };
+        let tag =
+            horizon_client::block_entity_item::stack_configured_entity_by(stack, kind, &own, op);
+        // The entity's own compound, its name and data merged in: it loads back.
+        let _ = self.apply_entity_nbt(target, tag);
+    }
     /// Ticks spawners, trial spawners and vaults near the player on a remote
     /// client (`tick_remote`).
     pub(super) fn tick_remote_spawners(&mut self) {

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

@@ -48,6 +48,7 @@ fn game() -> Game<'static> {
     game.block_ticks
         .add_empty_chunk(ChunkPos::new(0, 0))
         .unwrap();
+    game.load_ticking_neighbourhood(0, 0);
     assert!(game.run_command("fill 0 99 0 15 99 15 stone"));
     game
 }

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

@@ -346,13 +346,10 @@ impl Station {
     pub(super) fn new_kind(kind: Kind, pos: [i32; 3]) -> Self {
         Self::new(kind, pos)
     }
-    /// `StonecutterScreen.containerChanged`: without recipes to show, the
-    /// list scrolls back to the top.
+    /// `StonecutterScreen.containerChanged`: a changed input puts the list back at the top.
     pub(super) fn stonecutter_changed(&mut self) {
-        if self.inputs[0].is_none() || self.stone.recipes.is_empty() {
-            self.start = 0;
-            self.scroll = 0.0;
-        }
+        self.start = 0;
+        self.scroll = 0.0;
     }
     /// `StonecutterScreen.isScrollBarActive`.
     fn stonecutter_scrolls(&self) -> bool {
@@ -2364,7 +2361,7 @@ impl Game<'_> {
         if display.shows("minecraft:attribute_modifiers") {
             // The item's own modifiers, then its enchantments' for each slot
             // group (`ItemStack.forEachModifier`).
-            let mut modifiers = item_info.map(|i| i.modifiers.clone()).unwrap_or_default();
+            let mut modifiers = self.items().attribute_modifiers(stack);
             modifiers.extend(e.modifier_rows(stack));
             let base = |name: &str, default| {
                 self.player
@@ -3157,3 +3154,6 @@ mod brewing_tick;
 
 #[cfg(test)]
 mod brewing_changed_tests;
+
+#[cfg(test)]
+mod stonecutter_scroll_tests;

crates/horizon-client/src/game/stations/stonecutter_scroll_tests.rs

@@ -0,0 +1,86 @@
+//! `StonecutterScreen.containerChanged` (`StonecutterScreen.java:205-209`): the
+//! recipe list goes back to the top whenever the menu's input container
+//! changes, and only then.
+use super::super::native_machines::tests::server_game;
+use super::*;
+use horizon_client::menu::Input;
+
+fn deepslate(count: u32) -> ItemStack {
+    ItemStack::new("minecraft:deepslate", count)
+}
+
+/// The scroller at the end of its track: the last of the 17 deepslate
+/// recipes' rows (`startIndex` 8).
+fn scroll_to_bottom(game: &mut Game<'_>) {
+    game.station_scroll(-2.0);
+    let s = game.station.as_ref().unwrap();
+    assert_eq!(
+        (s.start, s.scroll),
+        (8, 1.0),
+        "the list is at its bottom row"
+    );
+}
+
+fn shown(game: &Game<'_>) -> (usize, f32) {
+    let s = game.station.as_ref().unwrap();
+    (s.start, s.scroll)
+}
+
+fn pick_recipe(game: &mut Game<'_>, index: i32) -> bool {
+    let mut taken = false;
+    game.menu_session(|menu, env, _| {
+        taken = menu.button(env, index);
+        Some(true)
+    });
+    taken
+}
+
+#[test]
+#[ignore = "needs prepared resources in HORIZON_TEST_RESOURCES"]
+fn the_stonecutter_list_returns_to_the_top_when_its_input_changes() {
+    let mut g = server_game();
+    assert!(g.open_station([0, 64, 0], "minecraft:stonecutter"));
+    // Two deepslate in the input: 17 recipes, so the list scrolls.
+    *g.slot_mut(9) = Some(deepslate(2));
+    assert!(g.menu_click(Some(9), 0, Input::Pickup));
+    assert!(g.menu_click(Some(INPUT), 0, Input::Pickup));
+    let s = g.station.as_ref().unwrap();
+    assert_eq!(s.inputs[0].as_ref().map(|i| i.count), Some(2));
+    assert_eq!(
+        s.stone.recipes.len(),
+        17,
+        "deepslate's stonecutting recipes"
+    );
+
+    // Taking a result uses up one deepslate, so the input changes: the list is
+    // back at the top.
+    assert!(pick_recipe(&mut g, 8));
+    scroll_to_bottom(&mut g);
+    assert!(g.menu_click(Some(RESULT), 0, Input::Pickup));
+    let s = g.station.as_ref().unwrap();
+    assert_eq!(s.inputs[0].as_ref().map(|i| i.count), Some(1));
+    assert_eq!(
+        shown(&g),
+        (0, 0.0),
+        "taking a result left the list scrolled"
+    );
+
+    // Adding the rest of the stack to the input: the same.
+    *g.slot_mut(10) = Some(deepslate(1));
+    scroll_to_bottom(&mut g);
+    // A click in the player's inventory swaps the carried result for the
+    // deepslate and does not touch the input: the list stays.
+    assert!(g.menu_click(Some(10), 0, Input::Pickup));
+    assert_eq!(g.carried, Some(deepslate(1)), "the swap took the deepslate");
+    assert_eq!(shown(&g), (8, 1.0), "an inventory click scrolled the list");
+    assert!(g.menu_click(Some(INPUT), 0, Input::Pickup));
+    assert_eq!(g.carried, None, "the deepslate went into the input");
+    let s = g.station.as_ref().unwrap();
+    assert_eq!(s.inputs[0].as_ref().map(|i| i.count), Some(2));
+    assert_eq!(shown(&g), (0, 0.0), "adding to the input left it scrolled");
+
+    // Picking a recipe does not touch the input either.
+    scroll_to_bottom(&mut g);
+    assert!(pick_recipe(&mut g, 0));
+    assert_eq!(shown(&g), (8, 1.0), "picking a recipe scrolled the list");
+}

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

@@ -660,10 +660,7 @@ impl Game<'_> {
                 }
             }
         }
-        if self.screen == Screen::Playing && self.replay.driver.is_some() {
-            return true;
-        }
-        false
+        self.screen == Screen::Playing && self.replay.driver.is_some()
     }
 
     /// The free camera flies by the movement keys, once per frame.