diff --git a/pite-editor/src/app.rs b/pite-editor/src/app.rs
deleted file mode 100644
index 329ada8..0000000
--- a/pite-editor/src/app.rs
+++ /dev/null
@@ -1,2390 +0,0 @@
-// SPDX-License-Identifier: MIT OR Apache-2.0
-use std::collections::{BTreeMap, HashMap, HashSet};
-use std::path::{Path, PathBuf};
-use std::sync::mpsc::Receiver;
-use std::time::Instant;
-
-use anyhow::Result;
-use eframe::egui;
-
-/// egui keys forwarded to the running scene, with the `pite.held` /
-/// `pite.pressed` names scripts use. Level-read each frame while playing.
-const GAME_KEYS: &[(egui::Key, &str)] = &[
-    (egui::Key::Space, "Space"),
-    (egui::Key::Enter, "Enter"),
-    (egui::Key::Escape, "Escape"),
-    (egui::Key::Tab, "Tab"),
-    (egui::Key::Backspace, "Backspace"),
-    (egui::Key::ArrowLeft, "ArrowLeft"),
-    (egui::Key::ArrowRight, "ArrowRight"),
-    (egui::Key::ArrowUp, "ArrowUp"),
-    (egui::Key::ArrowDown, "ArrowDown"),
-    (egui::Key::A, "A"),
-    (egui::Key::B, "B"),
-    (egui::Key::C, "C"),
-    (egui::Key::D, "D"),
-    (egui::Key::E, "E"),
-    (egui::Key::F, "F"),
-    (egui::Key::G, "G"),
-    (egui::Key::H, "H"),
-    (egui::Key::I, "I"),
-    (egui::Key::J, "J"),
-    (egui::Key::K, "K"),
-    (egui::Key::L, "L"),
-    (egui::Key::M, "M"),
-    (egui::Key::N, "N"),
-    (egui::Key::O, "O"),
-    (egui::Key::P, "P"),
-    (egui::Key::Q, "Q"),
-    (egui::Key::R, "R"),
-    (egui::Key::S, "S"),
-    (egui::Key::T, "T"),
-    (egui::Key::U, "U"),
-    (egui::Key::V, "V"),
-    (egui::Key::W, "W"),
-    (egui::Key::X, "X"),
-    (egui::Key::Y, "Y"),
-    (egui::Key::Z, "Z"),
-    (egui::Key::Num0, "0"),
-    (egui::Key::Num1, "1"),
-    (egui::Key::Num2, "2"),
-    (egui::Key::Num3, "3"),
-    (egui::Key::Num4, "4"),
-    (egui::Key::Num5, "5"),
-    (egui::Key::Num6, "6"),
-    (egui::Key::Num7, "7"),
-    (egui::Key::Num8, "8"),
-    (egui::Key::Num9, "9"),
-];
-
-/// Cursor in offscreen pixels from an egui pointer position. The texture
-/// stretches uniformly into its rect, so this is a pure rescale.
-fn viewport_cursor(rect: egui::Rect, view: (u32, u32), pointer: egui::Pos2) -> Option<(f64, f64)> {
-    if view.0 == 0 || view.1 == 0 || rect.width() <= 0.0 || rect.height() <= 0.0 {
-        return None;
-    }
-    let x = (pointer.x - rect.min.x) as f64 / rect.width() as f64 * view.0 as f64;
-    let y = (pointer.y - rect.min.y) as f64 / rect.height() as f64 * view.1 as f64;
-    Some((x, y))
-}
-/// Largest (width, height) with `view`'s aspect that fits inside `avail`.
-/// "Contain", not "fill": whichever axis binds first decides the scale, so
-/// the viewport grows and shrinks on both axes instead of blowing past the
-/// panel on the height axis when the editor is wide.
-fn fit_view(avail: egui::Vec2, view: (u32, u32)) -> egui::Vec2 {
-    let aspect = (view.0 as f32 / view.1.max(1) as f32).max(0.0001);
-    let avail = egui::Vec2::new(avail.x.max(1.0), avail.y.max(1.0));
-    if avail.x / avail.y > aspect {
-        egui::Vec2::new(avail.y * aspect, avail.y)
-    } else {
-        egui::Vec2::new(avail.x, avail.x / aspect)
-    }
-}
-use pite_core::{NodeId, PropValue};
-use pite_render::{OffscreenRenderer, Renderer2D};
-use pite_runtime::GameSession;
-
-use crate::icons::{self, Icon};
-use crate::lsp::{self, LspClient, LspOutcome};
-use crate::ops;
-
-#[derive(Clone, Copy, PartialEq)]
-enum Tab {
-    Viewport,
-    Code,
-}
-
-#[derive(Clone, Copy, PartialEq)]
-enum DropZone {
-    None,
-    Before,
-    Under,
-}
-
-/// Unsaved Project Settings edits. `None` while the window is closed; `base`
-/// carries the unknown keys so saving only swaps the known fields.
-struct SettingsDraft {
-    base: pite_project::PiteManifest,
-    name: String,
-    author: String,
-    main_scene: String,
-    python: String,
-    icon: String,
-    width: String,
-    height: String,
-    binary_name: String,
-    include: String,
-    error: String,
-}
-
-pub fn launch(scene: &Path) -> Result<()> {
-    let app = EditorApp::new(scene)?;
-    let options = eframe::NativeOptions {
-        viewport: egui::ViewportBuilder::default()
-            .with_inner_size([1280.0, 800.0])
-            .with_maximized(true)
-            .with_icon(
-                eframe::icon_data::from_png_bytes(include_bytes!("../../assets/icon.png"))
-                    .expect("assets/icon.png must be a valid PNG"),
-            ),
-        ..Default::default()
-    };
-    eframe::run_native(
-        "Pite Editor",
-        options,
-        Box::new(|cc| {
-            crate::theme::apply(&cc.egui_ctx);
-            Ok(Box::new(app) as Box<dyn eframe::App>)
-        }),
-    )
-    .map_err(|e| anyhow::anyhow!("editor failed: {e}"))?;
-    Ok(())
-}
-
-pub struct EditorApp {
-    session: GameSession,
-    scene_path: PathBuf,
-    project_dir: Option<PathBuf>,
-    selected: Option<String>,
-    console: Vec<String>,
-    seen_errors: HashSet<String>,
-    code_file: Option<PathBuf>,
-    code_text: String,
-    lsp: Option<LspClient>,
-    lsp_starter: Option<Receiver<LspOutcome>>,
-    lsp_status: String,
-    lsp_hint: String,
-    lsp_completions: Vec<lsp::CompletionItem>,
-    lsp_completion_open: bool,
-    lsp_completion_offset: usize,
-    lsp_completion_pending: Vec<(i64, usize)>,
-    lsp_completion_selected: usize,
-    /// Previous frame's galley row tops (galley space) for the code editor:
-    /// pixel-snapped, so the gutter tiles exactly instead of drifting on an
-    /// assumed pitch. Empty until the first paint.
-    code_row_tops: Vec<f32>,
-    /// `galley_pos.y - widget_top.y`: scroll-invariant content offset of the
-    /// galley origin, paired with `code_row_tops`.
-    code_galley_dy: f32,
-    playing: bool,
-    last_frame: Instant,
-    add_open: bool,
-    add_type: String,
-    add_name: String,
-    settings: Option<SettingsDraft>,
-    open_nodes: HashSet<String>,
-    open_seen: HashSet<String>,
-    viewport: Option<OffscreenRenderer>,
-    viewport_failed: bool,
-    viewport_tex: Option<egui::TextureHandle>,
-    viewport_dirty: bool,
-    /// Pointer was over the viewport last frame: game input goes to the
-    /// running scene only then, so editing text and shortcuts keep priority.
-    viewport_hovered: bool,
-    viewport_rect: Option<egui::Rect>,
-    /// Bound to the project's window size: the viewport must frame the scene the
-    /// way the game window does.
-    view_size: (u32, u32),
-    grip_hover: Option<String>,
-    tab: Tab,
-    recent: Vec<PathBuf>,
-    about_open: bool,
-}
-
-impl EditorApp {
-    pub fn new(scene: &Path) -> Result<Self> {
-        let session = GameSession::open(scene, false)?;
-        let project_dir = pite_project::find_project_root(scene);
-        let view_size = project_dir
-            .as_deref()
-            .and_then(|dir| pite_project::load_manifest(dir).ok())
-            .map_or_else(
-                || {
-                    let d = pite_project::ProjectMeta::default();
-                    (d.window_width, d.window_height)
-                },
-                |m| (m.project.window_width, m.project.window_height),
-            );
-        Ok(Self {
-            session,
-            scene_path: scene.to_path_buf(),
-            project_dir,
-            selected: None,
-            console: vec!["Pite editor ready.".to_string()],
-            seen_errors: HashSet::new(),
-            code_file: None,
-            code_text: String::new(),
-            lsp: None,
-            lsp_starter: None,
-            lsp_status: "lsp: off".to_string(),
-            lsp_hint: String::new(),
-            lsp_completions: Vec::new(),
-            lsp_completion_open: false,
-            lsp_completion_offset: 0,
-            lsp_completion_pending: Vec::new(),
-            lsp_completion_selected: 0,
-            code_row_tops: Vec::new(),
-            code_galley_dy: 0.0,
-            playing: false,
-            last_frame: Instant::now(),
-            add_open: false,
-            add_type: "Node2D".to_string(),
-            add_name: "NewNode".to_string(),
-            settings: None,
-            open_nodes: HashSet::new(),
-            open_seen: HashSet::new(),
-            viewport: None,
-            viewport_failed: false,
-            viewport_tex: None,
-            viewport_hovered: false,
-            viewport_rect: None,
-            view_size,
-            viewport_dirty: true,
-            grip_hover: None,
-            tab: Tab::Viewport,
-            recent: Self::load_recent(),
-            about_open: false,
-        })
-    }
-
-    fn log(&mut self, line: impl Into<String>) {
-        self.console.push(line.into());
-        if self.console.len() > 500 {
-            self.console.drain(..self.console.len() - 500);
-        }
-    }
-
-    fn drain_script_errors(&mut self) {
-        for err in self.session.errors() {
-            if self.seen_errors.insert(err.clone()) {
-                self.log(err);
-            }
-        }
-    }
-
-    fn toggle_play(&mut self) {
-        self.playing = !self.playing;
-        self.last_frame = Instant::now();
-        pite_script::input_clear();
-    }
-
-    /// Forward viewport input to the running scene's script input state.
-    /// Reads level state (`key_down`) and lets `input_set_key` derive edges;
-    /// runs before `session.frame()` so scripts consume this frame's state.
-    fn pump_game_input(&mut self, ctx: &egui::Context) {
-        let (view_w, view_h) = self.view_size;
-        self.session.set_viewport(view_w, view_h);
-        if !(self.playing && self.viewport_hovered) {
-            return;
-        }
-        let rect = self.viewport_rect;
-        ctx.input(|i| {
-            for (key, name) in GAME_KEYS {
-                pite_script::input_set_key(name, i.key_down(*key));
-            }
-            pite_script::input_set_key("Shift", i.modifiers.shift);
-            pite_script::input_set_key("Control", i.modifiers.ctrl);
-            pite_script::input_set_key("Alt", i.modifiers.alt);
-            if let (Some(rect), Some(pos)) = (rect, i.pointer.hover_pos()) {
-                if let Some((x, y)) = viewport_cursor(rect, (view_w, view_h), pos) {
-                    pite_script::input_set_mouse(x, y);
-                }
-            }
-            pite_script::input_set_key(
-                "MouseLeft",
-                i.pointer.button_down(egui::PointerButton::Primary),
-            );
-            pite_script::input_set_key(
-                "MouseRight",
-                i.pointer.button_down(egui::PointerButton::Secondary),
-            );
-            pite_script::input_set_key(
-                "MouseMiddle",
-                i.pointer.button_down(egui::PointerButton::Middle),
-            );
-        });
-    }
-
-    fn stop(&mut self) {
-        pite_script::input_clear();
-        match GameSession::open(&self.scene_path, false) {
-            Ok(session) => {
-                self.session = session;
-                self.playing = false;
-                self.viewport_dirty = true;
-                self.log("stopped, scene reset.");
-            }
-            Err(e) => self.log(format!("stop failed: {e:#}")),
-        }
-    }
-
-    fn save_scene(&mut self) {
-        let source = match std::fs::metadata(&self.scene_path) {
-            Ok(_) => match pite_scene::load_scene(&self.scene_path) {
-                Ok(doc) => Some(doc),
-                Err(e) => {
-                    self.log(format!(
-                        "save aborted: cannot read existing scene {}: {e:#}",
-                        self.scene_path.display()
-                    ));
-                    return;
-                }
-            },
-            Err(_) => None,
-        };
-        let scene_dir = self
-            .scene_path
-            .parent()
-            .map(Path::to_path_buf)
-            .unwrap_or_else(|| PathBuf::from("."));
-        let refs = ops::InstanceRefs {
-            scene_dir: &scene_dir,
-            project_dir: self.project_dir.as_deref(),
-        };
-        let built = self
-            .session
-            .host()
-            .with_tree(|tree| ops::build_doc(tree, source.as_ref(), Some(refs)));
-        match built.and_then(|doc| pite_scene::save_scene(&doc).map_err(anyhow::Error::from)) {
-            Ok(text) => match ops::save_text(&self.scene_path, &text) {
-                Ok(()) => {
-                    self.viewport_dirty = true;
-                    self.log(format!("saved scene {}", self.scene_path.display()));
-                }
-                Err(e) => self.log(format!("save scene failed: {e:#}")),
-            },
-            Err(e) => self.log(format!("save scene failed: {e:#}")),
-        }
-    }
-
-    fn view_size_for(project_dir: Option<&Path>) -> (u32, u32) {
-        project_dir
-            .and_then(|dir| pite_project::load_manifest(dir).ok())
-            .map_or_else(
-                || {
-                    let d = pite_project::ProjectMeta::default();
-                    (d.window_width, d.window_height)
-                },
-                |m| (m.project.window_width, m.project.window_height),
-            )
-    }
-
-    fn recent_file() -> Option<PathBuf> {
-        let base = std::env::var_os("XDG_CONFIG_HOME")
-            .map(PathBuf::from)
-            .filter(|p| !p.as_os_str().is_empty())
-            .or_else(|| std::env::var_os("HOME").map(|h| PathBuf::from(h).join(".config")))?;
-        Some(base.join("pite").join("recent.json"))
-    }
-
-    fn read_recent_file(path: &Path) -> Vec<PathBuf> {
-        let text = std::fs::read_to_string(path).unwrap_or_default();
-        let files: Vec<String> = serde_json::from_str(&text).unwrap_or_default();
-        files
-            .into_iter()
-            .map(PathBuf::from)
-            .filter(|p| p.is_file())
-            .collect()
-    }
-
-    fn write_recent_file(path: &Path, recent: &[PathBuf]) -> anyhow::Result<()> {
-        if let Some(parent) = path.parent() {
-            std::fs::create_dir_all(parent)?;
-        }
-        let files: Vec<String> = recent
-            .iter()
-            .map(|p| p.to_string_lossy().into_owned())
-            .collect();
-        std::fs::write(path, serde_json::to_string_pretty(&files)?)?;
-        Ok(())
-    }
-
-    fn load_recent() -> Vec<PathBuf> {
-        Self::recent_file()
-            .map(|p| Self::read_recent_file(&p))
-            .unwrap_or_default()
-    }
-
-    fn push_recent(&mut self, file: &Path) {
-        self.recent.retain(|p| p != file);
-        self.recent.insert(0, file.to_path_buf());
-        self.recent.truncate(10);
-        if let Some(path) = Self::recent_file() {
-            if let Err(e) = Self::write_recent_file(&path, &self.recent) {
-                self.log(format!("recent list not saved: {e:#}"));
-            }
-        }
-    }
-
-    /// Root-only scene: `New Scene` starts blank, never from the example scaffold.
-    fn blank_scene_text() -> String {
-        format!(
-            "format_version = {}\nroot = \"root\"\n\n[[node]]\nid = \"root\"\ntype = \"Node2D\"\nname = \"Main\"\n",
-            pite_scene::FORMAT_VERSION
-        )
-    }
-
-    fn open_scene_file(&mut self, file: &Path) {
-        match GameSession::open(file, false) {
-            Ok(session) => {
-                self.session = session;
-                self.scene_path = file.to_path_buf();
-                self.project_dir = pite_project::find_project_root(file);
-                self.view_size = Self::view_size_for(self.project_dir.as_deref());
-                self.selected = None;
-                self.viewport_dirty = true;
-                self.tab = Tab::Viewport;
-                self.push_recent(file);
-                self.log(format!("opened {}", file.display()));
-            }
-            Err(e) => self.log(format!("open failed: {e:#}")),
-        }
-    }
-
-    /// Native dialogs return the path as-is: enforce `.ptscn` so a bare
-    /// name cannot scatter extensionless scenes through the project.
-    fn with_scene_extension(mut path: PathBuf) -> PathBuf {
-        if path.extension().and_then(|e| e.to_str()) != Some("ptscn") {
-            path.set_extension("ptscn");
-        }
-        path
-    }
-
-    fn new_scene_via_dialog(&mut self) {
-        let Some(path) = rfd::FileDialog::new()
-            .add_filter("Pite scene", &["ptscn"])
-            .set_file_name("main.ptscn")
-            .save_file()
-        else {
-            return;
-        };
-        let path = Self::with_scene_extension(path);
-        match std::fs::write(&path, Self::blank_scene_text()) {
-            Ok(()) => self.open_scene_file(&path),
-            Err(e) => self.log(format!("new scene failed: {e:#}")),
-        }
-    }
-
-    fn open_scene_via_dialog(&mut self) {
-        let Some(path) = rfd::FileDialog::new()
-            .add_filter("Pite scene", &["ptscn"])
-            .pick_file()
-        else {
-            return;
-        };
-        self.open_scene_file(&path);
-    }
-
-    fn save_scene_as_via_dialog(&mut self) {
-        let Some(path) = rfd::FileDialog::new()
-            .add_filter("Pite scene", &["ptscn"])
-            .set_file_name(
-                self.scene_path
-                    .file_name()
-                    .and_then(|s| s.to_str())
-                    .unwrap_or("main.ptscn"),
-            )
-            .save_file()
-        else {
-            return;
-        };
-        self.scene_path = Self::with_scene_extension(path);
-        self.save_scene();
-        let path = self.scene_path.clone();
-        self.push_recent(&path);
-    }
-
-    fn debug_info(&mut self, ctx: &egui::Context) {
-        let lines = [
-            format!("pite {}", env!("CARGO_PKG_VERSION")),
-            format!("scene {}", self.scene_path.display()),
-            format!(
-                "project {}",
-                self.project_dir
-                    .as_deref()
-                    .map(|p| p.display().to_string())
-                    .unwrap_or_else(|| "-".to_string())
-            ),
-            format!("lsp {}", self.lsp_status),
-        ];
-        for line in &lines {
-            self.log(line.clone());
-        }
-        ctx.copy_text(lines.join("\n"));
-        self.log("debug info copied to clipboard.".to_string());
-    }
-
-    fn open_settings(&mut self) {
-        let dir = match self.project_dir.clone() {
-            Some(dir) => dir,
-            None => {
-                self.log("project settings: no project open.");
-                return;
-            }
-        };
-        match pite_project::load_manifest(&dir) {
-            Ok(base) => {
-                let binary_name = base.export.binary_name.clone().unwrap_or_default();
-                let include = base.export.include.join("\n");
-                let project = &base.project;
-                self.settings = Some(SettingsDraft {
-                    name: project.name.clone(),
-                    author: project.author.clone(),
-                    main_scene: project.main_scene.clone(),
-                    python: project.python.clone(),
-                    icon: project.icon.clone(),
-                    width: project.window_width.to_string(),
-                    height: project.window_height.to_string(),
-                    binary_name,
-                    include,
-                    error: String::new(),
-                    base,
-                });
-            }
-            Err(e) => self.log(format!("project settings: cannot load manifest: {e:#}")),
-        }
-    }
-
-    fn save_settings(&mut self) {
-        let (manifest, dir) = {
-            let draft = match self.settings.as_mut() {
-                Some(draft) => draft,
-                None => return,
-            };
-            let width = match draft.width.trim().parse::<u32>() {
-                Ok(width) => width,
-                Err(_) => {
-                    draft.error = format!("window width {:?} is not a number", draft.width);
-                    return;
-                }
-            };
-            let height = match draft.height.trim().parse::<u32>() {
-                Ok(height) => height,
-                Err(_) => {
-                    draft.error = format!("window height {:?} is not a number", draft.height);
-                    return;
-                }
-            };
-            let mut manifest = draft.base.clone();
-            let project = &mut manifest.project;
-            project.name = draft.name.clone();
-            project.author = draft.author.clone();
-            project.main_scene = draft.main_scene.clone();
-            project.python = draft.python.clone();
-            project.icon = draft.icon.clone();
-            project.window_width = width;
-            project.window_height = height;
-            let binary_name = draft.binary_name.trim().to_string();
-            manifest.export.binary_name = if binary_name.is_empty() {
-                None
-            } else {
-                Some(binary_name)
-            };
-            manifest.export.include = draft
-                .include
-                .lines()
-                .map(str::trim)
-                .filter(|line| !line.is_empty())
-                .map(str::to_string)
-                .collect();
-            let (errors, _) = pite_project::validate_manifest(&manifest);
-            if !errors.is_empty() {
-                draft.error = errors.join("\n");
-                return;
-            }
-            (
-                manifest,
-                self.project_dir
-                    .clone()
-                    .unwrap_or_else(|| PathBuf::from(".")),
-            )
-        };
-        match pite_project::save_manifest(&dir, &manifest) {
-            Ok(()) => {
-                self.view_size = (
-                    manifest.project.window_width,
-                    manifest.project.window_height,
-                );
-                self.viewport_dirty = true;
-                self.settings = None;
-                self.log("saved project settings.");
-            }
-            Err(e) => match self.settings.as_mut() {
-                Some(draft) => draft.error = format!("{e:#}"),
-                None => self.log(format!("save project settings failed: {e:#}")),
-            },
-        }
-    }
-
-    fn show_settings(&mut self, ctx: &egui::Context) {
-        let mut open = self.settings.is_some();
-        egui::Window::new("Project Settings")
-            .open(&mut open)
-            .show(ctx, |ui| {
-                let Some(draft) = self.settings.as_mut() else {
-                    return;
-                };
-                ui.label(format!(
-                    "engine version: {}",
-                    draft.base.project.pite_version
-                ));
-                ui.separator();
-                egui::Grid::new("settings-grid")
-                    .num_columns(2)
-                    .show(ui, |ui| {
-                        ui.label("Name");
-                        ui.text_edit_singleline(&mut draft.name);
-                        ui.end_row();
-                        ui.label("Author");
-                        ui.text_edit_singleline(&mut draft.author);
-                        ui.end_row();
-                        ui.label("Main scene");
-                        ui.text_edit_singleline(&mut draft.main_scene);
-                        ui.end_row();
-                        ui.label("Python");
-                        ui.text_edit_singleline(&mut draft.python);
-                        ui.end_row();
-                        ui.label("Icon");
-                        ui.text_edit_singleline(&mut draft.icon);
-                        ui.end_row();
-                        ui.label("Window width");
-                        ui.text_edit_singleline(&mut draft.width);
-                        ui.end_row();
-                        ui.label("Window height");
-                        ui.text_edit_singleline(&mut draft.height);
-                        ui.end_row();
-                    });
-                ui.separator();
-                ui.heading("Export");
-                egui::Grid::new("settings-export-grid")
-                    .num_columns(2)
-                    .show(ui, |ui| {
-                        ui.label("Binary name");
-                        ui.text_edit_singleline(&mut draft.binary_name);
-                        ui.end_row();
-                    });
-                ui.label("Extra staged files, one per line:");
-                ui.text_edit_multiline(&mut draft.include);
-                if !draft.error.is_empty() {
-                    ui.label(format!("error: {}", draft.error));
-                }
-                if ui.button("Save").clicked() {
-                    self.save_settings();
-                }
-            });
-        if !open {
-            self.settings = None;
-        }
-    }
-
-    fn delete_node(&mut self, id: &NodeId) {
-        match self
-            .session
-            .host()
-            .with_tree_mut(|t| ops::remove_node(t, id))
-        {
-            Ok(()) => {
-                if self.selected.as_deref() == Some(id.as_str()) {
-                    self.selected = None;
-                }
-                self.viewport_dirty = true;
-                self.log(format!("deleted {id}."));
-            }
-            Err(e) => self.log(format!("delete failed: {e:#}")),
-        }
-    }
-
-    fn move_sibling(&mut self, id: &NodeId, delta: i32) {
-        match self
-            .session
-            .host()
-            .with_tree_mut(|t| ops::move_sibling(t, id, delta))
-        {
-            Ok(()) => {
-                self.viewport_dirty = true;
-                self.log(format!("moved {id}."));
-            }
-            Err(e) => self.log(format!("move failed: {e:#}")),
-        }
-    }
-
-    fn drop_node(&mut self, dragged: &str, target: &NodeId, zone: DropZone) {
-        let dragged_id = NodeId::from(dragged);
-        if dragged_id == *target || zone == DropZone::None {
-            return;
-        }
-        let result = self.session.host().with_tree_mut(|t| match zone {
-            DropZone::Under => ops::move_node(t, &dragged_id, Some(target.clone())),
-            DropZone::Before => {
-                let parent = t
-                    .get(target)
-                    .and_then(|n| n.parent.clone())
-                    .ok_or_else(|| anyhow::anyhow!("cannot reorder at the top level"))?;
-                let sibs = t.children_of(&parent);
-                let pos = sibs
-                    .iter()
-                    .position(|s| s == target)
-                    .ok_or_else(|| anyhow::anyhow!("target `{target}` not found"))?;
-                ops::place_node(t, &dragged_id, &parent, pos)
-            }
-            DropZone::None => Ok(()),
-        });
-        match result {
-            Ok(()) => {
-                self.viewport_dirty = true;
-                self.log(format!("moved {dragged_id}."));
-            }
-            Err(e) => self.log(format!("move failed: {e:#}")),
-        }
-    }
-
-    fn set_prop(&mut self, id: &NodeId, key: &str, value: PropValue) {
-        let result = self
-            .session
-            .host()
-            .with_tree_mut(|t| ops::set_prop(t, id, key, value));
-        match result {
-            Ok(()) => self.viewport_dirty = true,
-            Err(e) => self.log(format!("set prop failed: {e:#}")),
-        }
-    }
-
-    fn is_open(&mut self, id: &str) -> bool {
-        if !self.open_seen.contains(id) {
-            self.open_seen.insert(id.to_string());
-            self.open_nodes.insert(id.to_string());
-            return true;
-        }
-        self.open_nodes.contains(id)
-    }
-
-    fn current_file_errors(&self) -> Vec<String> {
-        let name = self
-            .code_file
-            .as_ref()
-            .and_then(|f| f.file_name())
-            .and_then(|s| s.to_str())
-            .unwrap_or("");
-        if name.is_empty() {
-            return Vec::new();
-        }
-        self.session
-            .errors()
-            .into_iter()
-            .filter(|e| e.contains(name))
-            .collect()
-    }
-}
-
-impl eframe::App for EditorApp {
-    fn logic(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
-        let save_shortcut = ctx.input(|i| i.modifiers.command && i.key_pressed(egui::Key::S));
-        if save_shortcut {
-            self.save_scene();
-        }
-        let cmd = |key: egui::Key| {
-            ctx.input(|i| i.modifiers.command && !i.modifiers.shift && i.key_pressed(key))
-        };
-        let cmd_shift = |key: egui::Key| {
-            ctx.input(|i| i.modifiers.command && i.modifiers.shift && i.key_pressed(key))
-        };
-        if cmd(egui::Key::N) {
-            self.new_scene_via_dialog();
-        }
-        if cmd(egui::Key::O) {
-            self.open_scene_via_dialog();
-        }
-        if cmd_shift(egui::Key::S) {
-            self.save_scene_as_via_dialog();
-        }
-        if cmd(egui::Key::Q) {
-            ctx.send_viewport_cmd(egui::ViewportCommand::Close);
-        }
-        if self.playing {
-            let delta = self.last_frame.elapsed().as_secs_f64().min(0.1);
-            self.last_frame = Instant::now();
-            self.pump_game_input(ctx);
-            self.session.frame(delta);
-            self.drain_script_errors();
-            ctx.request_repaint();
-        }
-    }
-
-    fn ui(&mut self, ui: &mut egui::Ui, _frame: &mut eframe::Frame) {
-        let ctx = ui.ctx().clone();
-
-        egui::Panel::top("menu").show(ui, |ui| {
-            // Everything lives inside the MenuBar scope: MenuBar claims the
-            // full row width, so siblings after it in an outer horizontal
-            // row get zero space and vanish.
-            egui::MenuBar::new().ui(ui, |ui| {
-                ui.menu_button("Scene", |ui| {
-                    if ui.button("New Scene  Ctrl+N").clicked() {
-                        self.new_scene_via_dialog();
-                        ui.close();
-                    }
-                    if ui.button("Open Scene…  Ctrl+O").clicked() {
-                        self.open_scene_via_dialog();
-                        ui.close();
-                    }
-                    if self.recent.is_empty() {
-                        ui.add_enabled(false, egui::Button::new("Open Recent"));
-                    } else {
-                        ui.menu_button("Open Recent", |ui| {
-                            let recent = self.recent.clone();
-                            for path in &recent {
-                                if ui.button(path.display().to_string()).clicked() {
-                                    let path = path.clone();
-                                    self.open_scene_file(&path);
-                                    ui.close();
-                                }
-                            }
-                        });
-                    }
-                    ui.separator();
-                    if ui.button("Save Scene  Ctrl+S").clicked() {
-                        self.save_scene();
-                        ui.close();
-                    }
-                    if ui.button("Save Scene As…  Ctrl+Shift+S").clicked() {
-                        self.save_scene_as_via_dialog();
-                        ui.close();
-                    }
-                    ui.separator();
-                    if ui.button("Quit  Ctrl+Q").clicked() {
-                        ctx.send_viewport_cmd(egui::ViewportCommand::Close);
-                    }
-                });
-                ui.menu_button("Project", |ui| {
-                    if ui.button("Project Settings…").clicked() {
-                        self.open_settings();
-                        ui.close();
-                    }
-                });
-                ui.menu_button("Help", |ui| {
-                    if ui.button("Repository").clicked() {
-                        ctx.open_url(egui::OpenUrl::new_tab("https://github.com/piteengine/pite"));
-                    }
-                    if ui.button("Issues").clicked() {
-                        ctx.open_url(egui::OpenUrl::new_tab(
-                            "https://github.com/piteengine/pite/issues",
-                        ));
-                    }
-                    ui.separator();
-                    if ui.button("About Pite").clicked() {
-                        self.about_open = true;
-                        ui.close();
-                    }
-                    if ui.button("Copy Debug Info").clicked() {
-                        self.debug_info(ui.ctx());
-                        ui.close();
-                    }
-                });
-                // Transport controls pinned to the right end, Godot-style:
-                // the same actions as the Run menu, always visible.
-                // Right-to-left places the first widget rightmost, so Stop
-                // comes first to keep the Play, Stop order.
-                let (play_icon, play_tip) = if self.playing {
-                    (Icon::Pause, "Pause the scene")
-                } else {
-                    (Icon::Play, "Run the scene")
-                };
-                ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
-                    if icons::icon_button(ui, Icon::Stop, "Stop and reset the scene").clicked() {
-                        self.stop();
-                    }
-                    if icons::icon_button(ui, play_icon, play_tip).clicked() {
-                        self.toggle_play();
-                    }
-                });
-            });
-        });
-
-        if self.about_open {
-            egui::Window::new("About Pite")
-                .open(&mut self.about_open)
-                .show(ui, |ui| {
-                    ui.label(format!("Pite game engine {}", env!("CARGO_PKG_VERSION")));
-                    ui.label("Scene-tree 2D engine: Rust core, embedded Python, egui editor.");
-                    ui.horizontal(|ui| {
-                        if ui.button("Repository").clicked() {
-                            ui.ctx().open_url(egui::OpenUrl::new_tab(
-                                "https://github.com/piteengine/pite",
-                            ));
-                        }
-                        if ui.button("Issues").clicked() {
-                            ui.ctx().open_url(egui::OpenUrl::new_tab(
-                                "https://github.com/piteengine/pite/issues",
-                            ));
-                        }
-                    });
-                });
-        }
-
-        egui::Panel::left("left")
-            .default_size(240.0)
-            .min_size(240.0)
-            .max_size(360.0)
-            .resizable(true)
-            .show(ui, |ui| {
-                ui.horizontal(|ui| {
-                    ui.heading("Scene");
-                    if icons::icon_button(ui, Icon::Add, "Add a child node under the selection")
-                        .clicked()
-                    {
-                        self.add_open = true;
-                    }
-                });
-                if self.add_open {
-                    self.show_add_child(ui);
-                }
-                let tree_h = (ui.available_height() * 0.52).max(120.0);
-                egui::ScrollArea::vertical()
-                    .id_salt("tree")
-                    .max_height(tree_h)
-                    .show(ui, |ui| {
-                        let root = self.session.host().with_tree(|t| t.root().cloned());
-                        if let Some(root) = root {
-                            self.show_node(ui, &root);
-                        }
-                        let avail = ui.available_size();
-                        if avail.y > 8.0 {
-                            let (rect, resp) = ui.allocate_exact_size(
-                                egui::vec2(avail.x.max(1.0), avail.y),
-                                egui::Sense::hover(),
-                            );
-                            if egui::DragAndDrop::has_any_payload(ui.ctx())
-                                && resp.contains_pointer()
-                            {
-                                ui.painter().rect_stroke(
-                                    rect,
-                                    3.0,
-                                    egui::Stroke::new(1.5_f32, crate::theme::FAINT),
-                                    egui::StrokeKind::Middle,
-                                );
-                            }
-                            if let Some(dragged) = resp.dnd_release_payload::<String>() {
-                                if let Some(root) =
-                                    self.session.host().with_tree(|t| t.root().cloned())
-                                {
-                                    let dragged_id = NodeId::from(dragged.as_str());
-                                    let result = self.session.host().with_tree_mut(|t| {
-                                        let len = t.children_of(&root).len();
-                                        ops::place_node(t, &dragged_id, &root, len)
-                                    });
-                                    match result {
-                                        Ok(()) => {
-                                            self.viewport_dirty = true;
-                                            self.log(format!("moved {dragged_id}."));
-                                        }
-                                        Err(e) => self.log(format!("move failed: {e:#}")),
-                                    }
-                                }
-                            }
-                        }
-                    });
-                ui.separator();
-                ui.heading("Assets");
-                let rels = self.asset_rel_paths();
-                let refs: Vec<&str> = rels.iter().map(String::as_str).collect();
-                let root = self
-                    .project_dir
-                    .clone()
-                    .unwrap_or_else(|| PathBuf::from("."));
-                egui::ScrollArea::new([true, true])
-                    .id_salt("assets")
-                    .auto_shrink([false, false])
-                    .show(ui, |ui| {
-                        self.show_asset_dir(ui, &root, "", &refs);
-                    });
-            });
-
-        egui::Panel::right("inspector")
-            .default_size(240.0)
-            .min_size(240.0)
-            .max_size(360.0)
-            .resizable(true)
-            .show(ui, |ui| {
-                egui::ScrollArea::vertical()
-                    .id_salt("inspector")
-                    .auto_shrink([false, false])
-                    .show(ui, |ui| {
-                        ui.heading("Inspector");
-                        match self.selected.clone() {
-                            Some(id) => self.show_inspector(ui, &id),
-                            None => {
-                                ui.label("Select a node.");
-                            }
-                        }
-                    })
-            });
-
-        egui::Panel::bottom("console")
-            .default_size(120.0)
-            .min_size(120.0)
-            .max_size(240.0)
-            .resizable(true)
-            .show(ui, |ui| {
-                ui.heading("Console");
-                egui::ScrollArea::vertical()
-                    .id_salt("console")
-                    .auto_shrink([false, false])
-                    .stick_to_bottom(true)
-                    .show(ui, |ui| {
-                        for line in &self.console {
-                            ui.monospace(line);
-                        }
-                    });
-            });
-
-        egui::CentralPanel::default().show(ui, |ui| {
-            ui.horizontal(|ui| {
-                ui.selectable_value(&mut self.tab, Tab::Viewport, "Viewport");
-                ui.selectable_value(&mut self.tab, Tab::Code, "Code");
-            });
-            ui.separator();
-            ui.horizontal(|ui| match self.tab {
-                Tab::Viewport => {
-                    ui.label(self.scene_path.to_string_lossy().as_ref());
-                    if icons::icon_button(ui, Icon::Save, "Save scene (Ctrl+S)").clicked() {
-                        self.save_scene();
-                    }
-                }
-                Tab::Code => {
-                    if let Some(file) = self.code_file.clone() {
-                        ui.label(file.to_string_lossy().as_ref());
-                        if icons::icon_button(ui, Icon::Save, "Save script (Ctrl+S)").clicked() {
-                            self.save_code();
-                        }
-                    } else {
-                        ui.label("Open a .py file from Assets.");
-                    }
-                }
-            });
-            ui.separator();
-            match self.tab {
-                Tab::Viewport => self.show_viewport(ui),
-                Tab::Code => self.show_code(ui),
-            }
-        });
-
-        self.show_settings(&ctx);
-    }
-}
-
-impl EditorApp {
-    fn show_add_child(&mut self, ui: &mut egui::Ui) {
-        ui.separator();
-        let types = ops::registered_types();
-        if !types.contains(&self.add_type) {
-            self.add_type = types.first().cloned().unwrap_or_default();
-        }
-        egui::ComboBox::from_label("Type")
-            .selected_text(&self.add_type)
-            .show_ui(ui, |ui| {
-                for t in &types {
-                    ui.selectable_value(&mut self.add_type, t.clone(), t);
-                }
-            });
-        ui.text_edit_singleline(&mut self.add_name);
-        ui.horizontal(|ui| {
-            if ui.button("Add").clicked() {
-                let type_name = self.add_type.clone();
-                let name = self.add_name.clone();
-                let parent = self
-                    .selected
-                    .clone()
-                    .map(NodeId::from)
-                    .or_else(|| self.session.host().with_tree(|t| t.root().cloned()));
-                match self
-                    .session
-                    .host()
-                    .with_tree_mut(|t| ops::add_node(t, parent, &type_name, &name))
-                {
-                    Ok(id) => {
-                        self.selected = Some(id.to_string());
-                        self.add_open = false;
-                        self.viewport_dirty = true;
-                        self.log(format!("added {id} ({type_name})."));
-                    }
-                    Err(e) => self.log(format!("add node failed: {e:#}")),
-                }
-            }
-            if ui.button("Cancel").clicked() {
-                self.add_open = false;
-            }
-        });
-    }
-
-    fn show_node(&mut self, ui: &mut egui::Ui, id: &NodeId) {
-        let (name, type_name, children) = self
-            .session
-            .host()
-            .with_tree(|t| {
-                t.get(id)
-                    .map(|n| (n.name.clone(), n.type_name.clone(), t.children_of(id)))
-            })
-            .unwrap_or_else(|| ("?".to_string(), "?".to_string(), vec![]));
-        let script = self.session.host().with_tree(|t| {
-            t.get(id).and_then(|n| {
-                n.script
-                    .as_ref()
-                    .map(|s| (s.class_name.clone(), self.resolve_res(&s.path)))
-            })
-        });
-        let selected = self.selected.as_ref() == Some(&id.to_string());
-        let id_str = id.to_string();
-        let target = id.clone();
-        let is_root = self.session.host().with_tree(|t| t.root() == Some(id));
-        let open = self.is_open(&id_str);
-        let show_grip = self.grip_hover.as_deref() == Some(id_str.as_str());
-        let mut row_resp: Option<egui::Response> = None;
-        let mut grip_rect: Option<egui::Rect> = None;
-        let hresp = ui.horizontal(|ui| {
-            if !is_root {
-                let g = ui.dnd_drag_source(
-                    egui::Id::new(("tree-grip", id_str.clone())),
-                    id_str.clone(),
-                    |ui| {
-                        ui.allocate_exact_size(
-                            egui::Vec2::new(12.0, ui.text_style_height(&egui::TextStyle::Body)),
-                            egui::Sense::hover(),
-                        )
-                    },
-                );
-                grip_rect = Some(g.inner.0);
-            }
-            let r = ui.selectable_label(selected, format!("{name} ({type_name})"));
-            if let Some((class, file)) = script.as_ref() {
-                let (badge, resp) =
-                    ui.allocate_exact_size(egui::vec2(16.0, 16.0), egui::Sense::click());
-                if ui.is_rect_visible(badge) {
-                    icons::draw_icon(ui.painter(), badge, Icon::Script, crate::theme::FAINT);
-                }
-                let resp = resp.on_hover_text(format!("open {class}"));
-                if resp.clicked() {
-                    let file = file.clone();
-                    self.open_asset(&file);
-                }
-            }
-            if r.clicked() {
-                self.selected = Some(id_str.clone());
-            }
-            if !children.is_empty() && r.double_clicked() {
-                if open {
-                    self.open_nodes.remove(&id_str);
-                } else {
-                    self.open_nodes.insert(id_str.clone());
-                }
-            }
-            let menu_id = id.clone();
-            let menu_open = open;
-            let menu_kids = !children.is_empty();
-            let _ = r.context_menu(|ui| {
-                if ui.button("Delete").clicked() {
-                    self.delete_node(&menu_id);
-                    ui.close();
-                }
-                if ui.button("Move up").clicked() {
-                    self.move_sibling(&menu_id, -1);
-                    ui.close();
-                }
-                if ui.button("Move down").clicked() {
-                    self.move_sibling(&menu_id, 1);
-                    ui.close();
-                }
-                if menu_kids {
-                    let label = if menu_open { "Collapse" } else { "Expand" };
-                    if ui.button(label).clicked() {
-                        if menu_open {
-                            self.open_nodes.remove(&menu_id.to_string());
-                        } else {
-                            self.open_nodes.insert(menu_id.to_string());
-                        }
-                        ui.close();
-                    }
-                }
-            });
-            row_resp = Some(r);
-        });
-        if hresp.response.contains_pointer() {
-            self.grip_hover = Some(id_str.clone());
-        } else if self.grip_hover.as_deref() == Some(id_str.as_str()) {
-            self.grip_hover = None;
-        }
-        if show_grip {
-            if let (Some(g), Some(r)) = (grip_rect, &row_resp) {
-                let p = ui.painter();
-                let x = g.center().x;
-                let y = r.rect.center().y;
-                for row in 0..3 {
-                    for col in 0..2 {
-                        p.circle_filled(
-                            egui::Pos2::new(
-                                x - 2.25 + col as f32 * 4.5,
-                                y - 4.5 + row as f32 * 4.5,
-                            ),
-                            1.2,
-                            crate::theme::FAINT,
-                        );
-                    }
-                }
-            }
-        }
-        if let Some(r) = &row_resp {
-            let dragging = egui::DragAndDrop::has_any_payload(ui.ctx());
-            let zone = if dragging && r.contains_pointer() {
-                let pos = ui.ctx().pointer_hover_pos().unwrap_or(r.rect.center());
-                let frac = (pos.y - r.rect.top()) / r.rect.height().max(1.0);
-                if is_root {
-                    DropZone::Under
-                } else if frac < 0.35 || frac > 0.65 {
-                    DropZone::Before
-                } else {
-                    DropZone::Under
-                }
-            } else {
-                DropZone::None
-            };
-            let p = ui.painter();
-            let edge = egui::Stroke::new(1.5_f32, crate::theme::FAINT);
-            match zone {
-                DropZone::Before => {
-                    p.line_segment(
-                        [
-                            egui::Pos2::new(r.rect.left(), r.rect.top() + 1.0),
-                            egui::Pos2::new(r.rect.right(), r.rect.top() + 1.0),
-                        ],
-                        edge,
-                    );
-                }
-                DropZone::Under => {
-                    p.rect_stroke(r.rect, 3.0, edge, egui::StrokeKind::Middle);
-                }
-                DropZone::None => {}
-            }
-            if let Some(dragged) = r.dnd_release_payload::<String>() {
-                self.drop_node(dragged.as_str(), &target, zone);
-            }
-        }
-        if open && !children.is_empty() {
-            ui.indent(id_str, |ui| {
-                for child in children {
-                    self.show_node(ui, &child);
-                }
-            });
-        }
-    }
-
-    fn show_inspector(&mut self, ui: &mut egui::Ui, id: &str) {
-        let node_id = NodeId::from(id.to_string());
-        let snapshot = self.session.host().with_tree(|t| t.get(&node_id).cloned());
-        let Some(node) = snapshot else {
-            ui.label("Node no longer exists.");
-            return;
-        };
-        ui.label(format!("{} ({})", node.name, node.type_name));
-        let mut keys: Vec<String> = node.props.0.keys().cloned().collect();
-        keys.sort();
-        for key in keys {
-            let value = node
-                .props
-                .get(&key)
-                .cloned()
-                .unwrap_or(PropValue::Str(String::new()));
-            match value {
-                PropValue::Num(f) => {
-                    let mut v = f;
-                    ui.horizontal(|ui| {
-                        ui.label(&key);
-                        if ui.add(egui::DragValue::new(&mut v).speed(0.1)).changed() {
-                            self.set_prop(&node_id, &key, PropValue::Num(v));
-                        }
-                    });
-                }
-                PropValue::Int(i) => {
-                    let mut v = i;
-                    ui.horizontal(|ui| {
-                        ui.label(&key);
-                        if ui.add(egui::DragValue::new(&mut v)).changed() {
-                            self.set_prop(&node_id, &key, PropValue::Int(v));
-                        }
-                    });
-                }
-                PropValue::Str(s) => {
-                    let mut v = s;
-                    ui.horizontal(|ui| {
-                        ui.label(&key);
-                        if ui.text_edit_singleline(&mut v).changed() {
-                            self.set_prop(&node_id, &key, PropValue::Str(v));
-                        }
-                    });
-                }
-                PropValue::Bool(b) => {
-                    let mut v = b;
-                    ui.horizontal(|ui| {
-                        ui.label(&key);
-                        if ui.checkbox(&mut v, "").changed() {
-                            self.set_prop(&node_id, &key, PropValue::Bool(v));
-                        }
-                    });
-                }
-                PropValue::Vec2(x, y) => {
-                    let mut v = (x, y);
-                    ui.horizontal(|ui| {
-                        ui.label(&key);
-                        if ui.add(egui::DragValue::new(&mut v.0).speed(1.0)).changed()
-                            || ui.add(egui::DragValue::new(&mut v.1).speed(1.0)).changed()
-                        {
-                            self.set_prop(&node_id, &key, PropValue::Vec2(v.0, v.1));
-                        }
-                    });
-                }
-            }
-        }
-        match &node.script {
-            Some(script) => {
-                ui.label(format!("script: {} ({})", script.path, script.class_name));
-                let script_path = script.path.clone();
-                if ui.button("Open script").clicked() {
-                    let resolved = self.resolve_res(&script_path);
-                    self.open_asset(&resolved);
-                }
-            }
-            None => {
-                ui.label("no script attached.");
-            }
-        }
-    }
-
-    fn save_code(&mut self) {
-        let Some(file) = self.code_file.clone() else {
-            self.log("save: no script open.".to_string());
-            return;
-        };
-        match std::fs::write(&file, &self.code_text) {
-            Ok(()) => {
-                if self.code_is_python() {
-                    self.session.reload_script_path(&file);
-                }
-                self.log(format!("saved {}", file.display()));
-            }
-            Err(e) => self.log(format!("save failed: {e:#}")),
-        }
-    }
-
-    fn show_code(&mut self, ui: &mut egui::Ui) {
-        self.poll_lsp();
-        let diag_count = self.lsp.as_ref().map(|c| c.diagnostic_count()).unwrap_or(0);
-        ui.horizontal(|ui| {
-            if self.code_is_python() {
-                ui.label(&self.lsp_status);
-                if diag_count > 0 {
-                    ui.label(format!("diagnostics: {diag_count}"));
-                }
-                if !self.lsp_hint.is_empty() {
-                    ui.monospace(&self.lsp_hint);
-                }
-            } else {
-                let name = self
-                    .code_file
-                    .as_ref()
-                    .and_then(|f| f.file_name())
-                    .and_then(|s| s.to_str())
-                    .unwrap_or("no file open");
-                ui.label(format!("text: {name}"));
-            }
-        });
-        let mut marks = ops::gutter_marks(&self.current_file_errors());
-        marks.extend(self.lsp_marks());
-        marks.sort();
-        marks.dedup();
-        let mut error_lines = HashSet::new();
-        let mut messages = HashMap::new();
-        for (line, msg) in marks {
-            error_lines.insert(line);
-            messages.insert(line, msg);
-        }
-        let line_count = self.code_text.split('\n').count().max(1);
-        let row_h = ui.text_style_height(&egui::TextStyle::Monospace);
-        let font_id = egui::TextStyle::Monospace.resolve(ui.style());
-        let digits = line_count.to_string().len().max(2);
-        let strip_w = ui.fonts_mut(|fonts| {
-            let sample =
-                fonts.layout_no_wrap("8".repeat(digits), font_id.clone(), egui::Color32::WHITE);
-            sample.size().x + 10.0
-        });
-        // Fill the panel when the file is short: rows for the viewport
-        // height, so the editor keeps its old full-area look.
-        let min_rows = (ui.available_size().y / row_h) as usize;
-        egui::ScrollArea::vertical()
-            .id_salt("code-scroll")
-            .auto_shrink([false, false])
-            .show(ui, |ui| {
-                ui.horizontal_top(|ui| {
-                    ui.vertical(|ui| {
-                        // No gaps between rows: the placer would drift the
-                        // numbers away from the text rows down the file.
-                        ui.spacing_mut().item_spacing.y = 0.0;
-                        // Measured row geometry from last frame's galley: exact,
-                        // pixel-snapped tops, so long files cannot drift.
-                        let measured = self.code_row_tops.len() == line_count;
-                        if measured {
-                            let top = self.code_galley_dy + self.code_row_tops[0];
-                            if top > 0.0 {
-                                ui.add_space(top);
-                            }
-                        } else {
-                            // Match the editor frame's top inner margin so row 1
-                            // sits level with the first text row.
-                            ui.add_space(2.0);
-                        }
-                        for (idx, n) in (1..=line_count).enumerate() {
-                            let h = if measured {
-                                let tops = &self.code_row_tops;
-                                if idx + 1 < tops.len() {
-                                    tops[idx + 1] - tops[idx]
-                                } else if tops.len() >= 2 {
-                                    tops[tops.len() - 1] - tops[tops.len() - 2]
-                                } else {
-                                    row_h
-                                }
-                            } else {
-                                row_h
-                            };
-                            let (rect, resp) = ui
-                                .allocate_exact_size(egui::vec2(strip_w, h), egui::Sense::click());
-                            let color = if error_lines.contains(&n) {
-                                egui::Color32::YELLOW
-                            } else {
-                                crate::theme::FAINT
-                            };
-                            ui.painter().text(
-                                egui::pos2(rect.right() - 4.0, rect.center().y),
-                                egui::Align2::RIGHT_CENTER,
-                                n.to_string(),
-                                font_id.clone(),
-                                color,
-                            );
-                            let hovered = resp.hovered();
-                            let clicked = resp.clicked();
-                            if let Some(msg) = messages.get(&n) {
-                                resp.on_hover_text(msg.as_str());
-                            }
-                            if hovered {
-                                ui.set_cursor_icon(egui::CursorIcon::PointingHand);
-                            }
-                            if clicked {
-                                self.jump_to_line(ui.ctx(), n);
-                                ui.scroll_to_rect(rect, None);
-                            }
-                        }
-                    });
-                    // No wrapping: one text row per line keeps the gutter exact.
-                    // Highlighting rides the same layouter, colored by extension.
-                    let ext = self
-                        .code_file
-                        .as_ref()
-                        .and_then(|f| f.extension())
-                        .and_then(|e| e.to_str())
-                        .unwrap_or("")
-                        .to_ascii_lowercase();
-                    let mut layouter =
-                        |ui: &egui::Ui, text: &dyn egui::TextBuffer, wrap_width: f32| {
-                            let _ = wrap_width;
-                            crate::highlight::layout(ui, text.as_str(), &ext)
-                        };
-                    let edit_id = egui::Id::new("code-editor");
-                    let before_len = self.code_text.len();
-                    // Completion keys are consumed before the editor sees them:
-                    // arrows move the selection and Enter accepts, so typing
-                    // flows without the popup stealing or mangling keystrokes.
-                    // Escape is NOT focus-gated: egui core drops editor focus
-                    // on every plain Esc before widgets run, so a focus check
-                    // here would never observe the press.
-                    let mut completion_accept = false;
-                    if self.lsp_completion_open {
-                        if ui.ctx().memory(|m| m.focused()) == Some(edit_id) {
-                            if let Some(pre) =
-                                Self::code_cursor_byte(&self.code_text, ui.ctx(), &edit_id)
-                            {
-                                let matches = self.completion_filtered(pre).len();
-                                ui.ctx().input_mut(|i| {
-                                    let plain = i.modifiers.is_none();
-                                    if plain && i.key_pressed(egui::Key::ArrowDown) {
-                                        i.consume_key(egui::Modifiers::NONE, egui::Key::ArrowDown);
-                                        if matches > 0 {
-                                            self.lsp_completion_selected =
-                                                (self.lsp_completion_selected + 1) % matches;
-                                        }
-                                    } else if plain && i.key_pressed(egui::Key::ArrowUp) {
-                                        i.consume_key(egui::Modifiers::NONE, egui::Key::ArrowUp);
-                                        if matches > 0 {
-                                            self.lsp_completion_selected = self
-                                                .lsp_completion_selected
-                                                .checked_sub(1)
-                                                .unwrap_or(matches - 1);
-                                        }
-                                    } else if plain
-                                        && matches > 0
-                                        && i.key_pressed(egui::Key::Enter)
-                                    {
-                                        i.consume_key(egui::Modifiers::NONE, egui::Key::Enter);
-                                        completion_accept = true;
-                                    }
-                                });
-                            }
-                        }
-                        if ui.ctx().input_mut(|i| {
-                            i.modifiers.is_none()
-                                && i.key_pressed(egui::Key::Escape)
-                                && i.consume_key(egui::Modifiers::NONE, egui::Key::Escape)
-                        }) {
-                            self.close_completion();
-                            // Core already defocused the editor: hand focus
-                            // back so typing resumes without a click.
-                            ui.ctx().memory_mut(|m| m.request_focus(edit_id));
-                        }
-                    }
-                    // `show` (not `add`) exposes the galley so the popup can
-                    // anchor at the cursor instead of a fixed offset.
-                    let output = egui::TextEdit::multiline(&mut self.code_text)
-                        .code_editor()
-                        // Pinned id: gutter jumps address the editor across
-                        // frames, so it must not depend on widget order.
-                        .id(edit_id)
-                        // Full content height (+1 slack row) so the outer
-                        // scroll area owns scrolling and the gutter stays
-                        // in sync; the editor never scrolls internally.
-                        // At least the viewport height so short files still
-                        // fill the panel.
-                        .desired_rows((line_count + 1).max(min_rows))
-                        // Whatever width the gutter column leaves: the row
-                        // does not expand the editor on its own.
-                        .desired_width(ui.available_size().x)
-                        .layouter(&mut layouter)
-                        .show(ui);
-                    let resp = &output.response;
-                    // Record this frame's row geometry for next frame's
-                    // gutter: galley-space tops plus the scroll-invariant
-                    // widget offset, so numbers tile the true rows.
-                    if output.galley.rows.len() == line_count && !output.galley.rows.is_empty() {
-                        self.code_row_tops.clear();
-                        self.code_row_tops
-                            .extend(output.galley.rows.iter().map(|r| r.pos.y));
-                        self.code_galley_dy = output.galley_pos.y - output.response.rect.top();
-                    }
-                    let cursor_byte = Self::code_cursor_byte(&self.code_text, ui.ctx(), &resp.id);
-                    if resp.changed() {
-                        // Insertions only: backspace re-filters the live list
-                        // and the anchor check dismisses what no longer fits.
-                        let grew = self.code_text.len() > before_len;
-                        let last =
-                            cursor_byte.and_then(|off| self.code_text[..off].chars().next_back());
-                        let is_word = matches!(last, Some(c) if c.is_alphanumeric() || c == '_');
-                        let paren_at = cursor_byte
-                            .filter(|&off| self.code_text[..off].chars().next_back() == Some('('));
-                        self.code_changed(paren_at);
-                        if grew && last == Some('.') {
-                            self.request_completion_at(cursor_byte);
-                        } else if grew && is_word {
-                            self.request_completion_at(cursor_byte);
-                        } else if grew && !is_word {
-                            self.close_completion();
-                        }
-                    }
-                    if resp.has_focus() {
-                        let pressed = |key| {
-                            ui.ctx()
-                                .input(|i| i.modifiers.command && i.key_pressed(key))
-                        };
-                        if pressed(egui::Key::Space) {
-                            self.request_completion_at(cursor_byte);
-                        } else if pressed(egui::Key::H) {
-                            self.request_hover_at(cursor_byte);
-                        }
-                    }
-                    if completion_accept {
-                        self.accept_completion(ui.ctx(), cursor_byte);
-                    }
-                    let anchor = output.cursor_range.map(|range| {
-                        output.galley_pos
-                            + output
-                                .galley
-                                .pos_from_cursor(range.primary)
-                                .left_bottom()
-                                .to_vec2()
-                            + egui::vec2(0.0, 4.0)
-                    });
-                    self.show_completion_popup(ui, cursor_byte, anchor);
-                });
-            });
-    }
-
-    fn code_uri(&self) -> Option<String> {
-        self.code_file
-            .as_ref()
-            .map(|p| lsp::path_to_uri(p.as_path()))
-    }
-
-    /// The open file is a Python script: the only kind the LSP serves.
-    fn code_is_python(&self) -> bool {
-        self.code_file
-            .as_ref()
-            .and_then(|f| f.extension())
-            .and_then(|e| e.to_str())
-            == Some("py")
-    }
-
-    /// Plain-text files the code editor opens (same set the asset
-    /// browser shows with a gear icon); LSP stays Python-only.
-    fn editor_text_file(file: &Path) -> bool {
-        matches!(
-            file.extension()
-                .and_then(|e| e.to_str())
-                .map(|e| e.to_ascii_lowercase())
-                .as_deref(),
-            Some("py" | "toml" | "cfg" | "ini" | "json" | "yaml" | "yml")
-        )
-    }
-
-    fn code_cursor_byte(text: &str, ctx: &egui::Context, id: &egui::Id) -> Option<usize> {
-        let state = egui::widgets::text_edit::TextEditState::load(ctx, *id)?;
-        let range = state.cursor.char_range()?;
-        Some(lsp::byte_offset_of_char(text, range.primary.index.0))
-    }
-
-    /// Move the code editor's cursor to the start of 1-based `line` and focus
-    /// it. Callers scroll the outer area to the line themselves: the TextEdit
-    /// only scrolls on text/selection changes, never on a stored cursor.
-    fn jump_to_line(&mut self, ctx: &egui::Context, line: usize) {
-        let edit_id = egui::Id::new("code-editor");
-        let byte = lsp::line_start_byte(&self.code_text, line);
-        let index = self.code_text[..byte].chars().count();
-        Self::store_code_cursor(ctx, index);
-        ctx.memory_mut(|memory| memory.request_focus(edit_id));
-    }
-
-    fn store_code_cursor(ctx: &egui::Context, char_index: usize) {
-        let edit_id = egui::Id::new("code-editor");
-        if let Some(mut state) = egui::widgets::text_edit::TextEditState::load(ctx, edit_id) {
-            let cursor = egui::text::CCursor::new(char_index);
-            state
-                .cursor
-                .set_char_range(Some(egui::text::CCursorRange::one(cursor)));
-            state.store(ctx, edit_id);
-        }
-    }
-
-    fn ensure_lsp(&mut self) {
-        if self.lsp.is_some() || self.lsp_starter.is_some() {
-            return;
-        }
-        let Some(script) = self.code_file.clone() else {
-            return;
-        };
-        self.lsp_status = "lsp: starting…".to_string();
-        self.lsp_starter = Some(lsp::spawn_lsp(self.project_dir.clone(), &script));
-    }
-
-    fn poll_lsp(&mut self) {
-        if let Some(rx) = &self.lsp_starter {
-            if let Ok(outcome) = rx.try_recv() {
-                self.lsp_starter = None;
-                match outcome {
-                    LspOutcome::Ready {
-                        mut client,
-                        warning,
-                    } => {
-                        if let Some(w) = warning {
-                            self.log(w);
-                        }
-                        self.lsp_status = match &client.server_version {
-                            Some(v) => format!("lsp: ready ({v})"),
-                            None => "lsp: ready".to_string(),
-                        };
-                        if let Some(uri) = self.code_uri() {
-                            let text = self.code_text.clone();
-                            if self.code_is_python() {
-                                if let Err(e) = client.did_open(&uri, &text) {
-                                    self.log(format!("lsp: {e:#}"));
-                                }
-                            }
-                        }
-                        self.lsp = Some(client);
-                    }
-                    LspOutcome::Failed(msg) => {
-                        self.log(msg);
-                        self.lsp_status = "lsp: off (see console)".to_string();
-                    }
-                }
-            }
-        }
-        let mut hovers: Vec<String> = Vec::new();
-        let mut signatures: Vec<String> = Vec::new();
-        let mut notices: Vec<String> = Vec::new();
-        let mut dead: Option<String> = None;
-        if let Some(client) = self.lsp.as_mut() {
-            if let Some(msg) = client.poll() {
-                dead = Some(msg);
-            }
-            while let Some((id, items)) = client.take_completion() {
-                let hit = self
-                    .lsp_completion_pending
-                    .iter()
-                    .position(|(pending, _)| *pending == id);
-                if let Some(i) = hit {
-                    let (_, anchor) = self.lsp_completion_pending.remove(i);
-                    // Out-of-order guard: an older response landing after a
-                    // newer trigger must not resurrect a stale list.
-                    if anchor >= self.lsp_completion_offset {
-                        self.lsp_completion_offset = anchor;
-                        self.lsp_completion_selected = 0;
-                        self.lsp_completions = items;
-                        self.lsp_completion_open = !self.lsp_completions.is_empty();
-                    }
-                }
-            }
-            while let Some((_, text)) = client.take_hover() {
-                if !text.is_empty() {
-                    hovers.push(text);
-                }
-            }
-            while let Some((_, sigs)) = client.take_signature() {
-                signatures.extend(sigs);
-            }
-            while let Some(notice) = client.take_notice() {
-                notices.push(notice);
-            }
-        }
-        for notice in notices {
-            self.log(format!("lsp: {notice}"));
-        }
-        for hover in hovers {
-            self.log(format!("hover: {hover}"));
-        }
-        if !signatures.is_empty() {
-            self.lsp_hint = signatures.join(" | ");
-        }
-        if let Some(msg) = dead {
-            self.log(msg);
-            self.lsp = None;
-            self.lsp_status = "lsp: off (see console)".to_string();
-        }
-    }
-
-    fn lsp_marks(&self) -> Vec<(usize, String)> {
-        let Some(uri) = self.code_uri() else {
-            return Vec::new();
-        };
-        let Some(client) = self.lsp.as_ref() else {
-            return Vec::new();
-        };
-        client
-            .diagnostics_for_uri(&uri)
-            .iter()
-            .map(|d| {
-                let first = d.message.lines().next().unwrap_or("").to_string();
-                (d.line as usize + 1, format!("[lsp] {first}"))
-            })
-            .collect()
-    }
-
-    fn code_changed(&mut self, paren_at: Option<usize>) {
-        if !self.code_is_python() {
-            return;
-        };
-        let Some(uri) = self.code_uri() else {
-            return;
-        };
-        let text = self.code_text.clone();
-        let sig_pos = paren_at.map(|off| lsp::offset_to_position(&text, off));
-        let Some(client) = self.lsp.as_mut() else {
-            return;
-        };
-        if let Err(e) = client.did_change(&uri, &text) {
-            self.log(format!("lsp: {e:#}"));
-            return;
-        }
-        if let Some((line, ch)) = sig_pos {
-            if let Err(e) = client.request_signature(&uri, line, ch) {
-                self.log(format!("lsp: {e:#}"));
-            }
-        }
-    }
-
-    fn request_completion_at(&mut self, cursor_byte: Option<usize>) {
-        if !self.code_is_python() {
-            return;
-        }
-        let (Some(off), Some(uri)) = (cursor_byte, self.code_uri()) else {
-            return;
-        };
-        let (line, ch) = lsp::offset_to_position(&self.code_text, off);
-        match self.lsp.as_mut() {
-            Some(client) => match client.request_completion(&uri, line, ch) {
-                Ok(id) => {
-                    // Provisional anchor: the render-time check needs a base
-                    // before the response lands; the accepted response
-                    // overwrites it with the same value.
-                    self.lsp_completion_offset = off;
-                    self.lsp_completion_pending.push((id, off));
-                    if self.lsp_completion_pending.len() > 16 {
-                        let excess = self.lsp_completion_pending.len() - 16;
-                        self.lsp_completion_pending.drain(..excess);
-                    }
-                }
-                Err(e) => self.log(format!("lsp: {e:#}")),
-            },
-            None => self.log("lsp: no server (see console for the prerequisite).".to_string()),
-        }
-    }
-
-    /// Dismiss the popup and drop in-flight requests so late responses
-    /// cannot reopen it.
-    fn close_completion(&mut self) {
-        self.lsp_completion_open = false;
-        self.lsp_completion_pending.clear();
-        self.lsp_completion_selected = 0;
-    }
-
-    /// Indices into `lsp_completions` matching the text typed since the
-    /// trigger offset (case-insensitive prefix): optimistic narrowing
-    /// while a server refresh is still in flight.
-    fn completion_filtered(&self, cursor_byte: usize) -> Vec<usize> {
-        let base = self.lsp_completion_offset.min(self.code_text.len());
-        let cur = cursor_byte.min(self.code_text.len());
-        let prefix = self.code_text[base.min(cur)..cur].to_lowercase();
-        self.lsp_completions
-            .iter()
-            .enumerate()
-            .filter(|(_, item)| item.label.to_lowercase().starts_with(&prefix))
-            .map(|(i, _)| i)
-            .collect()
-    }
-
-    /// Insert the selected candidate, replacing the whole identifier under
-    /// the cursor (accepting mid-word must not duplicate its tail).
-    fn accept_completion(&mut self, ctx: &egui::Context, cursor_byte: Option<usize>) {
-        let Some(cur) = cursor_byte else { return };
-        let cur = cur.min(self.code_text.len());
-        let label = self
-            .completion_filtered(cur)
-            .get(self.lsp_completion_selected)
-            .copied()
-            .and_then(|i| self.lsp_completions.get(i))
-            .map(|item| item.label.clone());
-        let Some(label) = label else { return };
-        let start = lsp::word_start_before(&self.code_text, cur);
-        let end = lsp::word_end_after(&self.code_text, cur);
-        self.code_text.replace_range(start..end, &label);
-        let index = self.code_text[..start + label.len()].chars().count();
-        Self::store_code_cursor(ctx, index);
-        self.code_changed(None);
-        self.close_completion();
-    }
-
-    fn request_hover_at(&mut self, cursor_byte: Option<usize>) {
-        if !self.code_is_python() {
-            return;
-        }
-        let (Some(off), Some(uri)) = (cursor_byte, self.code_uri()) else {
-            return;
-        };
-        let (line, ch) = lsp::offset_to_position(&self.code_text, off);
-        match self.lsp.as_mut() {
-            Some(client) => {
-                if let Err(e) = client.request_hover(&uri, line, ch) {
-                    self.log(format!("lsp: {e:#}"));
-                }
-            }
-            None => self.log("lsp: no server (see console for the prerequisite).".to_string()),
-        }
-    }
-
-    fn show_completion_popup(
-        &mut self,
-        ui: &mut egui::Ui,
-        cursor_byte: Option<usize>,
-        anchor: Option<egui::Pos2>,
-    ) {
-        if !self.lsp_completion_open || self.lsp_completions.is_empty() {
-            return;
-        }
-        // The cursor must still sit in the word the request was made for;
-        // anything else means the list belongs to another spot.
-        let Some(cur) = cursor_byte else {
-            self.close_completion();
-            return;
-        };
-        let cur = cur.min(self.code_text.len());
-        let word_start = lsp::word_start_before(&self.code_text, cur);
-        if word_start > self.lsp_completion_offset || self.lsp_completion_offset > cur {
-            self.close_completion();
-            return;
-        }
-        let shown = self.completion_filtered(cur);
-        if shown.is_empty() {
-            return;
-        }
-        self.lsp_completion_selected = self.lsp_completion_selected.min(shown.len() - 1);
-        // No cursor, no popup: falling back to a corner rect is how the
-        // list ends up stranded at top-left after focus loss.
-        let Some(anchor) = anchor else {
-            self.close_completion();
-            return;
-        };
-        let mut pick: Option<usize> = None;
-        egui::Window::new("LSP completions")
-            .fixed_pos(anchor)
-            .constrain(true)
-            .title_bar(false)
-            .collapsible(false)
-            .resizable(false)
-            .show(ui, |ui| {
-                ui.set_max_height(220.0);
-                egui::ScrollArea::vertical().show(ui, |ui| {
-                    for (row, &i) in shown.iter().enumerate() {
-                        let item = &self.lsp_completions[i];
-                        let label = if item.detail.is_empty() {
-                            item.label.clone()
-                        } else {
-                            format!("{} — {}", item.label, item.detail)
-                        };
-                        let resp = ui.selectable_label(row == self.lsp_completion_selected, &label);
-                        if row == self.lsp_completion_selected {
-                            ui.scroll_to_rect(resp.rect, None);
-                        }
-                        if resp.clicked() {
-                            pick = Some(row);
-                        }
-                    }
-                });
-            });
-        if let Some(row) = pick {
-            self.lsp_completion_selected = row;
-            self.accept_completion(ui.ctx(), cursor_byte);
-        }
-    }
-
-    fn show_viewport(&mut self, ui: &mut egui::Ui) {
-        let (view_w, view_h) = self.view_size;
-        let want_refresh = self.playing || self.viewport_dirty;
-        if self.viewport.is_none() && !self.viewport_failed {
-            match OffscreenRenderer::new_offscreen(view_w, view_h) {
-                Ok(r) => {
-                    self.viewport = Some(r);
-                }
-                Err(e) => {
-                    self.viewport_failed = true;
-                    self.console
-                        .push(format!("viewport GPU unavailable, using fallback: {e:#}"));
-                }
-            }
-        }
-        let mut fresh_rgba: Option<Vec<u8>> = None;
-        let mut render_err: Option<String> = None;
-        if let Some(renderer) = self.viewport.as_mut() {
-            if want_refresh {
-                // The offscreen buffer is the design size: sync the session
-                // viewport here, not only while playing, or a fresh or just-
-                // stopped session still carries the (800, 600) init and the
-                // preview draws shrunken.
-                self.session.set_viewport(view_w, view_h);
-                let draw = renderer.begin_frame().and_then(|()| {
-                    self.session.draw_into(renderer)?;
-                    renderer.render_to_rgba()
-                });
-                match draw {
-                    Ok(rgba) => fresh_rgba = Some(rgba),
-                    Err(e) => render_err = Some(format!("viewport render failed: {e:#}")),
-                }
-            }
-        }
-        if let Some(rgba) = fresh_rgba {
-            let image =
-                egui::ColorImage::from_rgba_unmultiplied([view_w as usize, view_h as usize], &rgba);
-            match self.viewport_tex.as_mut() {
-                Some(handle) => handle.set(image, egui::TextureOptions::NEAREST),
-                None => {
-                    let handle = ui.ctx().load_texture(
-                        "pite-viewport",
-                        image,
-                        egui::TextureOptions::NEAREST,
-                    );
-                    self.viewport_tex = Some(handle);
-                }
-            }
-            self.viewport_dirty = false;
-        }
-        if let Some(err) = render_err {
-            self.log(err);
-        }
-        let textured = self.viewport.is_some() && self.viewport_tex.is_some();
-        let avail = ui.available_size();
-        let fitted = fit_view(avail, (view_w, view_h));
-        // Center the fitted rect in the space we measured: allocate the full
-        // avail, then paint into a centered sub-rect, so the viewport reads as
-        // framed content instead of content pinned to the top-left corner.
-        let (outer, _outer_painter) = ui.allocate_painter(avail, egui::Sense::hover());
-        let view_rect = egui::Rect::from_center_size(outer.rect.center(), fitted);
-        let resp = ui.interact(view_rect, ui.id().with("viewport"), egui::Sense::hover());
-        let painter = ui.painter_at(view_rect);
-        self.viewport_hovered = resp.hovered();
-        self.viewport_rect = Some(view_rect);
-        if textured {
-            if let Some(handle) = self.viewport_tex.as_ref() {
-                egui::Image::from_texture(handle).paint_at(ui, view_rect);
-            }
-        } else {
-            let nodes: Vec<(String, String, (f64, f64), String, (f64, f64))> =
-                self.session.host().with_tree(|t| {
-                    t.iter()
-                        .map(|n| {
-                            let pos = match n.props.get("position") {
-                                Some(PropValue::Vec2(x, y)) => (*x, *y),
-                                _ => (0.0, 0.0),
-                            };
-                            let text = match n.props.get("text") {
-                                Some(PropValue::Str(s)) => s.clone(),
-                                _ => String::new(),
-                            };
-                            let size = match n.props.get("size") {
-                                Some(PropValue::Vec2(w, h)) => (*w, *h),
-                                _ => (0.0, 0.0),
-                            };
-                            (n.id.to_string(), n.type_name.clone(), pos, text, size)
-                        })
-                        .collect()
-                });
-            let center = view_rect.center();
-            painter.rect_filled(view_rect, 0.0, crate::theme::BG);
-            for (id, type_name, (x, y), text, (w, h)) in nodes {
-                let p = center + egui::Vec2::new(x as f32, y as f32);
-                let color = if type_name == "Sprite2D" {
-                    egui::Color32::from_rgb(111, 179, 167)
-                } else {
-                    egui::Color32::from_rgb(124, 155, 184)
-                };
-                painter.circle_filled(p, 6.0, color);
-                if type_name == "Button" && w > 0.0 && h > 0.0 {
-                    painter.rect_stroke(
-                        egui::Rect::from_center_size(p, egui::Vec2::new(w as f32, h as f32)),
-                        4.0,
-                        egui::Stroke::new(1.0_f32, egui::Color32::from_rgb(111, 179, 167)),
-                        egui::StrokeKind::Middle,
-                    );
-                }
-                let caption = if text.is_empty() { id } else { text };
-                painter.text(
-                    p + egui::Vec2::new(10.0, -10.0),
-                    egui::Align2::LEFT_TOP,
-                    caption,
-                    egui::FontId::monospace(11.0),
-                    egui::Color32::from_rgb(201, 209, 216),
-                );
-            }
-        }
-    }
-
-    fn asset_files(&self) -> Vec<PathBuf> {
-        let root = self
-            .project_dir
-            .clone()
-            .unwrap_or_else(|| PathBuf::from("."));
-        let mut out = Vec::new();
-        let mut stack = vec![root.clone()];
-        while let Some(dir) = stack.pop() {
-            let Ok(entries) = std::fs::read_dir(&dir) else {
-                continue;
-            };
-            for entry in entries.flatten() {
-                let path = entry.path();
-                let name = entry.file_name().to_string_lossy().into_owned();
-                // Mirror pite-assets::scan_files: never show build output,
-                // VCS metadata, or hidden files in the Assets panel.
-                if name.starts_with('.') {
-                    continue;
-                }
-                if path.is_dir() {
-                    if name == "target"
-                        || name == "dist"
-                        || name == ".git"
-                        || name == pite_scene::cache::CACHE_DIR_NAME
-                    {
-                        continue;
-                    }
-                    if out.len() < 400 {
-                        stack.push(path);
-                    }
-                } else if out.len() < 400 {
-                    out.push(path);
-                }
-            }
-        }
-        out.sort();
-        out
-    }
-
-    fn asset_rel_paths(&self) -> Vec<String> {
-        let root = self
-            .project_dir
-            .clone()
-            .unwrap_or_else(|| PathBuf::from("."));
-        let mut out: Vec<String> = self
-            .asset_files()
-            .iter()
-            .filter_map(|f| {
-                f.strip_prefix(&root)
-                    .ok()
-                    .map(|rel| rel.to_string_lossy().replace('\\', "/"))
-            })
-            .collect();
-        out.sort();
-        out
-    }
-
-    fn show_asset_dir(&mut self, ui: &mut egui::Ui, root: &Path, dir: &str, paths: &[&str]) {
-        let mut subdirs: BTreeMap<&str, Vec<&str>> = BTreeMap::new();
-        let mut files: Vec<&str> = Vec::new();
-        for p in paths {
-            match p.split_once('/') {
-                Some((head, rest)) => subdirs.entry(head).or_default().push(rest),
-                None => files.push(p),
-            }
-        }
-        for (name, rest) in &subdirs {
-            let full = if dir.is_empty() {
-                name.to_string()
-            } else {
-                format!("{dir}/{name}")
-            };
-            let key = format!("assets:{full}");
-            let open = self.is_open(&key);
-            let mut toggled = false;
-            ui.horizontal(|ui| {
-                let (rect, icon_resp) =
-                    ui.allocate_exact_size(egui::vec2(16.0, 16.0), egui::Sense::click());
-                if ui.is_rect_visible(rect) {
-                    icons::draw_icon(ui.painter(), rect, icons::Icon::Folder, crate::theme::FAINT);
-                }
-                toggled = icon_resp.clicked() || ui.label(*name).clicked();
-            });
-            if toggled {
-                if open {
-                    self.open_nodes.remove(&key);
-                } else {
-                    self.open_nodes.insert(key.clone());
-                }
-            }
-            if toggled != open {
-                ui.indent(format!("assets-indent:{full}"), |ui| {
-                    self.show_asset_dir(ui, root, &full, rest)
-                });
-            }
-        }
-        for name in &files {
-            let rel = if dir.is_empty() {
-                name.to_string()
-            } else {
-                format!("{dir}/{name}")
-            };
-            let kind = match name
-                .rsplit('.')
-                .next()
-                .unwrap_or("")
-                .to_ascii_lowercase()
-                .as_str()
-            {
-                "py" => icons::Icon::Script,
-                "ptscn" => icons::Icon::Scene,
-                "toml" | "cfg" | "ini" | "json" | "yaml" | "yml" => icons::Icon::Gear,
-                "png" | "jpg" | "jpeg" | "gif" | "bmp" | "webp" | "svg" => icons::Icon::Image,
-                "wav" | "ogg" | "mp3" | "flac" => icons::Icon::Audio,
-                _ => icons::Icon::File,
-            };
-            let mut opened = false;
-            ui.horizontal(|ui| {
-                let (rect, icon_resp) =
-                    ui.allocate_exact_size(egui::vec2(16.0, 16.0), egui::Sense::click());
-                if ui.is_rect_visible(rect) {
-                    icons::draw_icon(ui.painter(), rect, kind, crate::theme::FAINT);
-                }
-                opened = icon_resp.clicked()
-                    || ui
-                        .add(egui::Label::new(*name).sense(egui::Sense::click()))
-                        .clicked();
-            });
-            if opened {
-                let abs = root.join(rel.replace('/', std::path::MAIN_SEPARATOR_STR));
-                self.open_asset(&abs);
-            }
-        }
-    }
-
-    fn resolve_res(&self, res_path: &str) -> PathBuf {
-        if let Some(rel) = res_path.strip_prefix("res://") {
-            self.project_dir
-                .as_deref()
-                .unwrap_or(Path::new("."))
-                .join(rel)
-        } else {
-            PathBuf::from(res_path)
-        }
-    }
-
-    fn open_asset(&mut self, file: &Path) {
-        if Self::editor_text_file(file) {
-            match std::fs::read_to_string(file) {
-                Ok(text) => {
-                    self.code_file = Some(file.to_path_buf());
-                    self.code_text = text;
-                    self.tab = Tab::Code;
-                    self.close_completion();
-                    self.lsp_hint.clear();
-                    // LSP stays Python-only: text files open with no
-                    // did_open, so pyright never sees them.
-                    if self.code_is_python() {
-                        self.ensure_lsp();
-                        let uri = self.code_uri();
-                        let text = self.code_text.clone();
-                        if let (Some(client), Some(uri)) = (self.lsp.as_mut(), uri) {
-                            if let Err(e) = client.did_open(&uri, &text) {
-                                self.log(format!("lsp: {e:#}"));
-                            }
-                        }
-                    }
-                }
-                Err(e) => self.log(format!("cannot open {}: {e:#}", file.display())),
-            }
-        } else if file.extension().and_then(|e| e.to_str()) == Some("ptscn") {
-            self.open_scene_file(file);
-        } else {
-            self.log(format!("no opener for {}", file.display()));
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn cursor_maps_viewport_corners() {
-        let rect =
-            egui::Rect::from_min_size(egui::Pos2::new(10.0, 20.0), egui::Vec2::new(400.0, 300.0));
-        assert_eq!(
-            viewport_cursor(rect, (800, 600), egui::Pos2::new(10.0, 20.0)),
-            Some((0.0, 0.0))
-        );
-        assert_eq!(
-            viewport_cursor(rect, (800, 600), egui::Pos2::new(410.0, 320.0)),
-            Some((800.0, 600.0))
-        );
-        assert_eq!(
-            viewport_cursor(rect, (800, 600), egui::Pos2::new(210.0, 170.0)),
-            Some((400.0, 300.0))
-        );
-    }
-
-    #[test]
-    fn cursor_rejects_degenerate_viewport() {
-        let rect = egui::Rect::from_min_size(egui::Pos2::ZERO, egui::Vec2::new(400.0, 300.0));
-        assert_eq!(
-            viewport_cursor(rect, (0, 600), egui::Pos2::new(10.0, 10.0)),
-            None
-        );
-        let flat = egui::Rect::from_min_size(egui::Pos2::ZERO, egui::Vec2::new(0.0, 300.0));
-        assert_eq!(
-            viewport_cursor(flat, (800, 600), egui::Pos2::new(10.0, 10.0)),
-            None
-        );
-    }
-
-    #[test]
-    fn viewport_fits_available_space_on_both_axes() {
-        let view = (800, 600);
-        // Wide panel: height binds, width shrinks to match.
-        let wide = fit_view(egui::Vec2::new(2000.0, 400.0), view);
-        assert!((wide.y - 400.0).abs() < 0.01, "got {wide:?}");
-        assert!((wide.x - 400.0 * 4.0 / 3.0).abs() < 0.01, "got {wide:?}");
-        // Tall panel: width binds, height shrinks to match.
-        let tall = fit_view(egui::Vec2::new(400.0, 2000.0), view);
-        assert!((tall.x - 400.0).abs() < 0.01, "got {tall:?}");
-        assert!((tall.y - 300.0).abs() < 0.01, "got {tall:?}");
-        // Never exceeds the panel on either axis, at any panel shape.
-        for (ax, ay) in [(2000.0, 400.0), (400.0, 2000.0), (800.0, 600.0), (1.0, 1.0)] {
-            let f = fit_view(egui::Vec2::new(ax, ay), view);
-            assert!(
-                f.x <= ax + 0.01 && f.y <= ay + 0.01,
-                "{f:?} exceeds {ax}x{ay}"
-            );
-        }
-        // Degenerate input stays positive.
-        let tiny = fit_view(egui::Vec2::ZERO, view);
-        assert!(tiny.x > 0.0 && tiny.y > 0.0);
-    }
-
-    #[test]
-    fn viewport_is_centered_in_its_panel() {
-        // 4:3 scene, panel wider than tall: fitted box is height-bound and must
-        // sit centered horizontally, with equal margins on both sides.
-        let avail = egui::Vec2::new(1000.0, 300.0);
-        let fitted = fit_view(avail, (800, 600));
-        let outer = egui::Rect::from_min_size(egui::Pos2::ZERO, avail);
-        let view = egui::Rect::from_center_size(outer.center(), fitted);
-        assert!((view.left() - (outer.right() - view.right())).abs() < 0.01);
-        assert!(view.width() <= outer.width() + 0.01);
-        assert!(view.height() <= outer.height() + 0.01);
-    }
-
-    #[test]
-    fn editor_opens_gear_group_as_text() {
-        for name in [
-            "a.py", "p.toml", "c.cfg", "c.ini", "d.json", "e.yaml", "f.yml", "G.TOML",
-        ] {
-            assert!(EditorApp::editor_text_file(Path::new(name)), "{name}");
-        }
-        for name in ["a.png", "b.wav", "c.ptscn", "noext", "a.pyx"] {
-            assert!(!EditorApp::editor_text_file(Path::new(name)), "{name}");
-        }
-    }
-
-    #[test]
-    fn recent_list_round_trips_and_drops_missing() {
-        let dir = std::env::temp_dir().join(format!("pite-recent-{}", std::process::id()));
-        std::fs::create_dir_all(&dir).unwrap();
-        let present = dir.join("a.ptscn");
-        std::fs::write(&present, "x").unwrap();
-        let file = dir.join("recent.json");
-        let recent = vec![present.clone(), dir.join("gone.ptscn")];
-        EditorApp::write_recent_file(&file, &recent).unwrap();
-        assert_eq!(EditorApp::read_recent_file(&file), vec![present]);
-        std::fs::remove_dir_all(&dir).unwrap();
-    }
-
-    #[test]
-    fn save_dialog_path_keeps_scene_extension() {
-        assert_eq!(
-            EditorApp::with_scene_extension(PathBuf::from("s/main")),
-            PathBuf::from("s/main.ptscn")
-        );
-        assert_eq!(
-            EditorApp::with_scene_extension(PathBuf::from("s/main.ptscn")),
-            PathBuf::from("s/main.ptscn")
-        );
-    }
-
-    #[test]
-    fn blank_scene_tracks_format_version() {
-        let text = EditorApp::blank_scene_text();
-        assert!(
-            text.starts_with(&format!(
-                "format_version = {}\n",
-                pite_scene::FORMAT_VERSION
-            )),
-            "{text}"
-        );
-        assert!(text.contains("id = \"root\""));
-    }
-}
diff --git a/pite-editor/src/app/assets.rs b/pite-editor/src/app/assets.rs
new file mode 100644
index 0000000..630c160
--- /dev/null
+++ b/pite-editor/src/app/assets.rs
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use std::collections::BTreeMap;
+use std::path::{Path, PathBuf};
+
+use eframe::egui;
+
+use crate::icons;
+
+use super::{EditorApp, Tab};
+
+impl EditorApp {
+    pub(super) fn asset_files(&self) -> Vec<PathBuf> {
+        let root = self
+            .project_dir
+            .clone()
+            .unwrap_or_else(|| PathBuf::from("."));
+        let mut out = Vec::new();
+        let mut stack = vec![root.clone()];
+        while let Some(dir) = stack.pop() {
+            let Ok(entries) = std::fs::read_dir(&dir) else {
+                continue;
+            };
+            for entry in entries.flatten() {
+                let path = entry.path();
+                let name = entry.file_name().to_string_lossy().into_owned();
+                // Mirror pite-assets::scan_files: never show build output,
+                // VCS metadata, or hidden files in the Assets panel.
+                if name.starts_with('.') {
+                    continue;
+                }
+                if path.is_dir() {
+                    if name == "target"
+                        || name == "dist"
+                        || name == ".git"
+                        || name == pite_scene::cache::CACHE_DIR_NAME
+                    {
+                        continue;
+                    }
+                    if out.len() < 400 {
+                        stack.push(path);
+                    }
+                } else if out.len() < 400 {
+                    out.push(path);
+                }
+            }
+        }
+        out.sort();
+        out
+    }
+
+    pub(super) fn asset_rel_paths(&self) -> Vec<String> {
+        let root = self
+            .project_dir
+            .clone()
+            .unwrap_or_else(|| PathBuf::from("."));
+        let mut out: Vec<String> = self
+            .asset_files()
+            .iter()
+            .filter_map(|f| {
+                f.strip_prefix(&root)
+                    .ok()
+                    .map(|rel| rel.to_string_lossy().replace('\\', "/"))
+            })
+            .collect();
+        out.sort();
+        out
+    }
+
+    pub(super) fn show_asset_dir(
+        &mut self,
+        ui: &mut egui::Ui,
+        root: &Path,
+        dir: &str,
+        paths: &[&str],
+    ) {
+        let mut subdirs: BTreeMap<&str, Vec<&str>> = BTreeMap::new();
+        let mut files: Vec<&str> = Vec::new();
+        for p in paths {
+            match p.split_once('/') {
+                Some((head, rest)) => subdirs.entry(head).or_default().push(rest),
+                None => files.push(p),
+            }
+        }
+        for (name, rest) in &subdirs {
+            let full = if dir.is_empty() {
+                name.to_string()
+            } else {
+                format!("{dir}/{name}")
+            };
+            let key = format!("assets:{full}");
+            let open = self.is_open(&key);
+            let mut toggled = false;
+            ui.horizontal(|ui| {
+                let (rect, icon_resp) =
+                    ui.allocate_exact_size(egui::vec2(16.0, 16.0), egui::Sense::click());
+                if ui.is_rect_visible(rect) {
+                    icons::draw_icon(ui.painter(), rect, icons::Icon::Folder, crate::theme::FAINT);
+                }
+                toggled = icon_resp.clicked() || ui.label(*name).clicked();
+            });
+            if toggled {
+                if open {
+                    self.open_nodes.remove(&key);
+                } else {
+                    self.open_nodes.insert(key.clone());
+                }
+            }
+            if toggled != open {
+                ui.indent(format!("assets-indent:{full}"), |ui| {
+                    self.show_asset_dir(ui, root, &full, rest)
+                });
+            }
+        }
+        for name in &files {
+            let rel = if dir.is_empty() {
+                name.to_string()
+            } else {
+                format!("{dir}/{name}")
+            };
+            let kind = match name
+                .rsplit('.')
+                .next()
+                .unwrap_or("")
+                .to_ascii_lowercase()
+                .as_str()
+            {
+                "py" => icons::Icon::Script,
+                "ptscn" => icons::Icon::Scene,
+                "toml" | "cfg" | "ini" | "json" | "yaml" | "yml" => icons::Icon::Gear,
+                "png" | "jpg" | "jpeg" | "gif" | "bmp" | "webp" | "svg" => icons::Icon::Image,
+                "wav" | "ogg" | "mp3" | "flac" => icons::Icon::Audio,
+                _ => icons::Icon::File,
+            };
+            let mut opened = false;
+            ui.horizontal(|ui| {
+                let (rect, icon_resp) =
+                    ui.allocate_exact_size(egui::vec2(16.0, 16.0), egui::Sense::click());
+                if ui.is_rect_visible(rect) {
+                    icons::draw_icon(ui.painter(), rect, kind, crate::theme::FAINT);
+                }
+                opened = icon_resp.clicked()
+                    || ui
+                        .add(egui::Label::new(*name).sense(egui::Sense::click()))
+                        .clicked();
+            });
+            if opened {
+                let abs = root.join(rel.replace('/', std::path::MAIN_SEPARATOR_STR));
+                self.open_asset(&abs);
+            }
+        }
+    }
+
+    pub(super) fn resolve_res(&self, res_path: &str) -> PathBuf {
+        if let Some(rel) = res_path.strip_prefix("res://") {
+            self.project_dir
+                .as_deref()
+                .unwrap_or(Path::new("."))
+                .join(rel)
+        } else {
+            PathBuf::from(res_path)
+        }
+    }
+
+    pub(super) fn open_asset(&mut self, file: &Path) {
+        if Self::editor_text_file(file) {
+            match std::fs::read_to_string(file) {
+                Ok(text) => {
+                    self.code_file = Some(file.to_path_buf());
+                    self.code_text = text;
+                    self.tab = Tab::Code;
+                    self.close_completion();
+                    self.lsp_hint.clear();
+                    // LSP stays Python-only: text files open with no
+                    // did_open, so pyright never sees them.
+                    if self.code_is_python() {
+                        self.ensure_lsp();
+                        let uri = self.code_uri();
+                        let text = self.code_text.clone();
+                        if let (Some(client), Some(uri)) = (self.lsp.as_mut(), uri) {
+                            if let Err(e) = client.did_open(&uri, &text) {
+                                self.log(format!("lsp: {e:#}"));
+                            }
+                        }
+                    }
+                }
+                Err(e) => self.log(format!("cannot open {}: {e:#}", file.display())),
+            }
+        } else if file.extension().and_then(|e| e.to_str()) == Some("ptscn") {
+            self.open_scene_file(file);
+        } else {
+            self.log(format!("no opener for {}", file.display()));
+        }
+    }
+}
diff --git a/pite-editor/src/app/code.rs b/pite-editor/src/app/code.rs
new file mode 100644
index 0000000..cdc6db7
--- /dev/null
+++ b/pite-editor/src/app/code.rs
@@ -0,0 +1,643 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use std::collections::{HashMap, HashSet};
+use std::path::Path;
+
+use eframe::egui;
+
+use crate::lsp::{self, LspOutcome};
+use crate::ops;
+
+use super::EditorApp;
+
+impl EditorApp {
+    pub(super) fn current_file_errors(&self) -> Vec<String> {
+        let name = self
+            .code_file
+            .as_ref()
+            .and_then(|f| f.file_name())
+            .and_then(|s| s.to_str())
+            .unwrap_or("");
+        if name.is_empty() {
+            return Vec::new();
+        }
+        self.session
+            .errors()
+            .into_iter()
+            .filter(|e| e.contains(name))
+            .collect()
+    }
+
+    pub(super) fn save_code(&mut self) {
+        let Some(file) = self.code_file.clone() else {
+            self.log("save: no script open.".to_string());
+            return;
+        };
+        match std::fs::write(&file, &self.code_text) {
+            Ok(()) => {
+                if self.code_is_python() {
+                    self.session.reload_script_path(&file);
+                }
+                self.log(format!("saved {}", file.display()));
+            }
+            Err(e) => self.log(format!("save failed: {e:#}")),
+        }
+    }
+
+    pub(super) fn show_code(&mut self, ui: &mut egui::Ui) {
+        self.poll_lsp();
+        let diag_count = self.lsp.as_ref().map(|c| c.diagnostic_count()).unwrap_or(0);
+        ui.horizontal(|ui| {
+            if self.code_is_python() {
+                ui.label(&self.lsp_status);
+                if diag_count > 0 {
+                    ui.label(format!("diagnostics: {diag_count}"));
+                }
+                if !self.lsp_hint.is_empty() {
+                    ui.monospace(&self.lsp_hint);
+                }
+            } else {
+                let name = self
+                    .code_file
+                    .as_ref()
+                    .and_then(|f| f.file_name())
+                    .and_then(|s| s.to_str())
+                    .unwrap_or("no file open");
+                ui.label(format!("text: {name}"));
+            }
+        });
+        let mut marks = ops::gutter_marks(&self.current_file_errors());
+        marks.extend(self.lsp_marks());
+        marks.sort();
+        marks.dedup();
+        let mut error_lines = HashSet::new();
+        let mut messages = HashMap::new();
+        for (line, msg) in marks {
+            error_lines.insert(line);
+            messages.insert(line, msg);
+        }
+        let line_count = self.code_text.split('\n').count().max(1);
+        let row_h = ui.text_style_height(&egui::TextStyle::Monospace);
+        let font_id = egui::TextStyle::Monospace.resolve(ui.style());
+        let digits = line_count.to_string().len().max(2);
+        let strip_w = ui.fonts_mut(|fonts| {
+            let sample =
+                fonts.layout_no_wrap("8".repeat(digits), font_id.clone(), egui::Color32::WHITE);
+            sample.size().x + 10.0
+        });
+        // Fill the panel when the file is short: rows for the viewport
+        // height, so the editor keeps its old full-area look.
+        let min_rows = (ui.available_size().y / row_h) as usize;
+        egui::ScrollArea::vertical()
+            .id_salt("code-scroll")
+            .auto_shrink([false, false])
+            .show(ui, |ui| {
+                ui.horizontal_top(|ui| {
+                    ui.vertical(|ui| {
+                        // No gaps between rows: the placer would drift the
+                        // numbers away from the text rows down the file.
+                        ui.spacing_mut().item_spacing.y = 0.0;
+                        // Measured row geometry from last frame's galley: exact,
+                        // pixel-snapped tops, so long files cannot drift.
+                        let measured = self.code_row_tops.len() == line_count;
+                        if measured {
+                            let top = self.code_galley_dy + self.code_row_tops[0];
+                            if top > 0.0 {
+                                ui.add_space(top);
+                            }
+                        } else {
+                            // Match the editor frame's top inner margin so row 1
+                            // sits level with the first text row.
+                            ui.add_space(2.0);
+                        }
+                        for (idx, n) in (1..=line_count).enumerate() {
+                            let h = if measured {
+                                let tops = &self.code_row_tops;
+                                if idx + 1 < tops.len() {
+                                    tops[idx + 1] - tops[idx]
+                                } else if tops.len() >= 2 {
+                                    tops[tops.len() - 1] - tops[tops.len() - 2]
+                                } else {
+                                    row_h
+                                }
+                            } else {
+                                row_h
+                            };
+                            let (rect, resp) = ui
+                                .allocate_exact_size(egui::vec2(strip_w, h), egui::Sense::click());
+                            let color = if error_lines.contains(&n) {
+                                egui::Color32::YELLOW
+                            } else {
+                                crate::theme::FAINT
+                            };
+                            ui.painter().text(
+                                egui::pos2(rect.right() - 4.0, rect.center().y),
+                                egui::Align2::RIGHT_CENTER,
+                                n.to_string(),
+                                font_id.clone(),
+                                color,
+                            );
+                            let hovered = resp.hovered();
+                            let clicked = resp.clicked();
+                            if let Some(msg) = messages.get(&n) {
+                                resp.on_hover_text(msg.as_str());
+                            }
+                            if hovered {
+                                ui.set_cursor_icon(egui::CursorIcon::PointingHand);
+                            }
+                            if clicked {
+                                self.jump_to_line(ui.ctx(), n);
+                                ui.scroll_to_rect(rect, None);
+                            }
+                        }
+                    });
+                    // No wrapping: one text row per line keeps the gutter exact.
+                    // Highlighting rides the same layouter, colored by extension.
+                    let ext = self
+                        .code_file
+                        .as_ref()
+                        .and_then(|f| f.extension())
+                        .and_then(|e| e.to_str())
+                        .unwrap_or("")
+                        .to_ascii_lowercase();
+                    let mut layouter =
+                        |ui: &egui::Ui, text: &dyn egui::TextBuffer, wrap_width: f32| {
+                            let _ = wrap_width;
+                            crate::highlight::layout(ui, text.as_str(), &ext)
+                        };
+                    let edit_id = egui::Id::new("code-editor");
+                    let before_len = self.code_text.len();
+                    // Completion keys are consumed before the editor sees them:
+                    // arrows move the selection and Enter accepts, so typing
+                    // flows without the popup stealing or mangling keystrokes.
+                    // Escape is NOT focus-gated: egui core drops editor focus
+                    // on every plain Esc before widgets run, so a focus check
+                    // here would never observe the press.
+                    let mut completion_accept = false;
+                    if self.lsp_completion_open {
+                        if ui.ctx().memory(|m| m.focused()) == Some(edit_id) {
+                            if let Some(pre) =
+                                Self::code_cursor_byte(&self.code_text, ui.ctx(), &edit_id)
+                            {
+                                let matches = self.completion_filtered(pre).len();
+                                ui.ctx().input_mut(|i| {
+                                    let plain = i.modifiers.is_none();
+                                    if plain && i.key_pressed(egui::Key::ArrowDown) {
+                                        i.consume_key(egui::Modifiers::NONE, egui::Key::ArrowDown);
+                                        if matches > 0 {
+                                            self.lsp_completion_selected =
+                                                (self.lsp_completion_selected + 1) % matches;
+                                        }
+                                    } else if plain && i.key_pressed(egui::Key::ArrowUp) {
+                                        i.consume_key(egui::Modifiers::NONE, egui::Key::ArrowUp);
+                                        if matches > 0 {
+                                            self.lsp_completion_selected = self
+                                                .lsp_completion_selected
+                                                .checked_sub(1)
+                                                .unwrap_or(matches - 1);
+                                        }
+                                    } else if plain
+                                        && matches > 0
+                                        && i.key_pressed(egui::Key::Enter)
+                                    {
+                                        i.consume_key(egui::Modifiers::NONE, egui::Key::Enter);
+                                        completion_accept = true;
+                                    }
+                                });
+                            }
+                        }
+                        if ui.ctx().input_mut(|i| {
+                            i.modifiers.is_none()
+                                && i.key_pressed(egui::Key::Escape)
+                                && i.consume_key(egui::Modifiers::NONE, egui::Key::Escape)
+                        }) {
+                            self.close_completion();
+                            // Core already defocused the editor: hand focus
+                            // back so typing resumes without a click.
+                            ui.ctx().memory_mut(|m| m.request_focus(edit_id));
+                        }
+                    }
+                    // `show` (not `add`) exposes the galley so the popup can
+                    // anchor at the cursor instead of a fixed offset.
+                    let output = egui::TextEdit::multiline(&mut self.code_text)
+                        .code_editor()
+                        // Pinned id: gutter jumps address the editor across
+                        // frames, so it must not depend on widget order.
+                        .id(edit_id)
+                        // Full content height (+1 slack row) so the outer
+                        // scroll area owns scrolling and the gutter stays
+                        // in sync; the editor never scrolls internally.
+                        // At least the viewport height so short files still
+                        // fill the panel.
+                        .desired_rows((line_count + 1).max(min_rows))
+                        // Whatever width the gutter column leaves: the row
+                        // does not expand the editor on its own.
+                        .desired_width(ui.available_size().x)
+                        .layouter(&mut layouter)
+                        .show(ui);
+                    let resp = &output.response;
+                    // Record this frame's row geometry for next frame's
+                    // gutter: galley-space tops plus the scroll-invariant
+                    // widget offset, so numbers tile the true rows.
+                    if output.galley.rows.len() == line_count && !output.galley.rows.is_empty() {
+                        self.code_row_tops.clear();
+                        self.code_row_tops
+                            .extend(output.galley.rows.iter().map(|r| r.pos.y));
+                        self.code_galley_dy = output.galley_pos.y - output.response.rect.top();
+                    }
+                    let cursor_byte = Self::code_cursor_byte(&self.code_text, ui.ctx(), &resp.id);
+                    if resp.changed() {
+                        // Insertions only: backspace re-filters the live list
+                        // and the anchor check dismisses what no longer fits.
+                        let grew = self.code_text.len() > before_len;
+                        let last =
+                            cursor_byte.and_then(|off| self.code_text[..off].chars().next_back());
+                        let is_word = matches!(last, Some(c) if c.is_alphanumeric() || c == '_');
+                        let paren_at = cursor_byte
+                            .filter(|&off| self.code_text[..off].chars().next_back() == Some('('));
+                        self.code_changed(paren_at);
+                        if grew && last == Some('.') {
+                            self.request_completion_at(cursor_byte);
+                        } else if grew && is_word {
+                            self.request_completion_at(cursor_byte);
+                        } else if grew && !is_word {
+                            self.close_completion();
+                        }
+                    }
+                    if resp.has_focus() {
+                        let pressed = |key| {
+                            ui.ctx()
+                                .input(|i| i.modifiers.command && i.key_pressed(key))
+                        };
+                        if pressed(egui::Key::Space) {
+                            self.request_completion_at(cursor_byte);
+                        } else if pressed(egui::Key::H) {
+                            self.request_hover_at(cursor_byte);
+                        }
+                    }
+                    if completion_accept {
+                        self.accept_completion(ui.ctx(), cursor_byte);
+                    }
+                    let anchor = output.cursor_range.map(|range| {
+                        output.galley_pos
+                            + output
+                                .galley
+                                .pos_from_cursor(range.primary)
+                                .left_bottom()
+                                .to_vec2()
+                            + egui::vec2(0.0, 4.0)
+                    });
+                    self.show_completion_popup(ui, cursor_byte, anchor);
+                });
+            });
+    }
+
+    pub(super) fn code_uri(&self) -> Option<String> {
+        self.code_file
+            .as_ref()
+            .map(|p| lsp::path_to_uri(p.as_path()))
+    }
+
+    /// The open file is a Python script: the only kind the LSP serves.
+    pub(super) fn code_is_python(&self) -> bool {
+        self.code_file
+            .as_ref()
+            .and_then(|f| f.extension())
+            .and_then(|e| e.to_str())
+            == Some("py")
+    }
+
+    /// Plain-text files the code editor opens (same set the asset
+    /// browser shows with a gear icon); LSP stays Python-only.
+    pub(super) fn editor_text_file(file: &Path) -> bool {
+        matches!(
+            file.extension()
+                .and_then(|e| e.to_str())
+                .map(|e| e.to_ascii_lowercase())
+                .as_deref(),
+            Some("py" | "toml" | "cfg" | "ini" | "json" | "yaml" | "yml")
+        )
+    }
+
+    pub(super) fn code_cursor_byte(
+        text: &str,
+        ctx: &egui::Context,
+        id: &egui::Id,
+    ) -> Option<usize> {
+        let state = egui::widgets::text_edit::TextEditState::load(ctx, *id)?;
+        let range = state.cursor.char_range()?;
+        Some(lsp::byte_offset_of_char(text, range.primary.index.0))
+    }
+
+    /// Move the code editor's cursor to the start of 1-based `line` and focus
+    /// it. Callers scroll the outer area to the line themselves: the TextEdit
+    /// only scrolls on text/selection changes, never on a stored cursor.
+    pub(super) fn jump_to_line(&mut self, ctx: &egui::Context, line: usize) {
+        let edit_id = egui::Id::new("code-editor");
+        let byte = lsp::line_start_byte(&self.code_text, line);
+        let index = self.code_text[..byte].chars().count();
+        Self::store_code_cursor(ctx, index);
+        ctx.memory_mut(|memory| memory.request_focus(edit_id));
+    }
+
+    pub(super) fn store_code_cursor(ctx: &egui::Context, char_index: usize) {
+        let edit_id = egui::Id::new("code-editor");
+        if let Some(mut state) = egui::widgets::text_edit::TextEditState::load(ctx, edit_id) {
+            let cursor = egui::text::CCursor::new(char_index);
+            state
+                .cursor
+                .set_char_range(Some(egui::text::CCursorRange::one(cursor)));
+            state.store(ctx, edit_id);
+        }
+    }
+
+    pub(super) fn ensure_lsp(&mut self) {
+        if self.lsp.is_some() || self.lsp_starter.is_some() {
+            return;
+        }
+        let Some(script) = self.code_file.clone() else {
+            return;
+        };
+        self.lsp_status = "lsp: starting…".to_string();
+        self.lsp_starter = Some(lsp::spawn_lsp(self.project_dir.clone(), &script));
+    }
+
+    pub(super) fn poll_lsp(&mut self) {
+        if let Some(rx) = &self.lsp_starter {
+            if let Ok(outcome) = rx.try_recv() {
+                self.lsp_starter = None;
+                match outcome {
+                    LspOutcome::Ready {
+                        mut client,
+                        warning,
+                    } => {
+                        if let Some(w) = warning {
+                            self.log(w);
+                        }
+                        self.lsp_status = match &client.server_version {
+                            Some(v) => format!("lsp: ready ({v})"),
+                            None => "lsp: ready".to_string(),
+                        };
+                        if let Some(uri) = self.code_uri() {
+                            let text = self.code_text.clone();
+                            if self.code_is_python() {
+                                if let Err(e) = client.did_open(&uri, &text) {
+                                    self.log(format!("lsp: {e:#}"));
+                                }
+                            }
+                        }
+                        self.lsp = Some(client);
+                    }
+                    LspOutcome::Failed(msg) => {
+                        self.log(msg);
+                        self.lsp_status = "lsp: off (see console)".to_string();
+                    }
+                }
+            }
+        }
+        let mut hovers: Vec<String> = Vec::new();
+        let mut signatures: Vec<String> = Vec::new();
+        let mut notices: Vec<String> = Vec::new();
+        let mut dead: Option<String> = None;
+        if let Some(client) = self.lsp.as_mut() {
+            if let Some(msg) = client.poll() {
+                dead = Some(msg);
+            }
+            while let Some((id, items)) = client.take_completion() {
+                let hit = self
+                    .lsp_completion_pending
+                    .iter()
+                    .position(|(pending, _)| *pending == id);
+                if let Some(i) = hit {
+                    let (_, anchor) = self.lsp_completion_pending.remove(i);
+                    // Out-of-order guard: an older response landing after a
+                    // newer trigger must not resurrect a stale list.
+                    if anchor >= self.lsp_completion_offset {
+                        self.lsp_completion_offset = anchor;
+                        self.lsp_completion_selected = 0;
+                        self.lsp_completions = items;
+                        self.lsp_completion_open = !self.lsp_completions.is_empty();
+                    }
+                }
+            }
+            while let Some((_, text)) = client.take_hover() {
+                if !text.is_empty() {
+                    hovers.push(text);
+                }
+            }
+            while let Some((_, sigs)) = client.take_signature() {
+                signatures.extend(sigs);
+            }
+            while let Some(notice) = client.take_notice() {
+                notices.push(notice);
+            }
+        }
+        for notice in notices {
+            self.log(format!("lsp: {notice}"));
+        }
+        for hover in hovers {
+            self.log(format!("hover: {hover}"));
+        }
+        if !signatures.is_empty() {
+            self.lsp_hint = signatures.join(" | ");
+        }
+        if let Some(msg) = dead {
+            self.log(msg);
+            self.lsp = None;
+            self.lsp_status = "lsp: off (see console)".to_string();
+        }
+    }
+
+    pub(super) fn lsp_marks(&self) -> Vec<(usize, String)> {
+        let Some(uri) = self.code_uri() else {
+            return Vec::new();
+        };
+        let Some(client) = self.lsp.as_ref() else {
+            return Vec::new();
+        };
+        client
+            .diagnostics_for_uri(&uri)
+            .iter()
+            .map(|d| {
+                let first = d.message.lines().next().unwrap_or("").to_string();
+                (d.line as usize + 1, format!("[lsp] {first}"))
+            })
+            .collect()
+    }
+
+    pub(super) fn code_changed(&mut self, paren_at: Option<usize>) {
+        if !self.code_is_python() {
+            return;
+        };
+        let Some(uri) = self.code_uri() else {
+            return;
+        };
+        let text = self.code_text.clone();
+        let sig_pos = paren_at.map(|off| lsp::offset_to_position(&text, off));
+        let Some(client) = self.lsp.as_mut() else {
+            return;
+        };
+        if let Err(e) = client.did_change(&uri, &text) {
+            self.log(format!("lsp: {e:#}"));
+            return;
+        }
+        if let Some((line, ch)) = sig_pos {
+            if let Err(e) = client.request_signature(&uri, line, ch) {
+                self.log(format!("lsp: {e:#}"));
+            }
+        }
+    }
+
+    pub(super) fn request_completion_at(&mut self, cursor_byte: Option<usize>) {
+        if !self.code_is_python() {
+            return;
+        }
+        let (Some(off), Some(uri)) = (cursor_byte, self.code_uri()) else {
+            return;
+        };
+        let (line, ch) = lsp::offset_to_position(&self.code_text, off);
+        match self.lsp.as_mut() {
+            Some(client) => match client.request_completion(&uri, line, ch) {
+                Ok(id) => {
+                    // Provisional anchor: the render-time check needs a base
+                    // before the response lands; the accepted response
+                    // overwrites it with the same value.
+                    self.lsp_completion_offset = off;
+                    self.lsp_completion_pending.push((id, off));
+                    if self.lsp_completion_pending.len() > 16 {
+                        let excess = self.lsp_completion_pending.len() - 16;
+                        self.lsp_completion_pending.drain(..excess);
+                    }
+                }
+                Err(e) => self.log(format!("lsp: {e:#}")),
+            },
+            None => self.log("lsp: no server (see console for the prerequisite).".to_string()),
+        }
+    }
+
+    /// Dismiss the popup and drop in-flight requests so late responses
+    /// cannot reopen it.
+    pub(super) fn close_completion(&mut self) {
+        self.lsp_completion_open = false;
+        self.lsp_completion_pending.clear();
+        self.lsp_completion_selected = 0;
+    }
+
+    /// Indices into `lsp_completions` matching the text typed since the
+    /// trigger offset (case-insensitive prefix): optimistic narrowing
+    /// while a server refresh is still in flight.
+    pub(super) fn completion_filtered(&self, cursor_byte: usize) -> Vec<usize> {
+        let base = self.lsp_completion_offset.min(self.code_text.len());
+        let cur = cursor_byte.min(self.code_text.len());
+        let prefix = self.code_text[base.min(cur)..cur].to_lowercase();
+        self.lsp_completions
+            .iter()
+            .enumerate()
+            .filter(|(_, item)| item.label.to_lowercase().starts_with(&prefix))
+            .map(|(i, _)| i)
+            .collect()
+    }
+
+    /// Insert the selected candidate, replacing the whole identifier under
+    /// the cursor (accepting mid-word must not duplicate its tail).
+    pub(super) fn accept_completion(&mut self, ctx: &egui::Context, cursor_byte: Option<usize>) {
+        let Some(cur) = cursor_byte else { return };
+        let cur = cur.min(self.code_text.len());
+        let label = self
+            .completion_filtered(cur)
+            .get(self.lsp_completion_selected)
+            .copied()
+            .and_then(|i| self.lsp_completions.get(i))
+            .map(|item| item.label.clone());
+        let Some(label) = label else { return };
+        let start = lsp::word_start_before(&self.code_text, cur);
+        let end = lsp::word_end_after(&self.code_text, cur);
+        self.code_text.replace_range(start..end, &label);
+        let index = self.code_text[..start + label.len()].chars().count();
+        Self::store_code_cursor(ctx, index);
+        self.code_changed(None);
+        self.close_completion();
+    }
+
+    pub(super) fn request_hover_at(&mut self, cursor_byte: Option<usize>) {
+        if !self.code_is_python() {
+            return;
+        }
+        let (Some(off), Some(uri)) = (cursor_byte, self.code_uri()) else {
+            return;
+        };
+        let (line, ch) = lsp::offset_to_position(&self.code_text, off);
+        match self.lsp.as_mut() {
+            Some(client) => {
+                if let Err(e) = client.request_hover(&uri, line, ch) {
+                    self.log(format!("lsp: {e:#}"));
+                }
+            }
+            None => self.log("lsp: no server (see console for the prerequisite).".to_string()),
+        }
+    }
+
+    pub(super) fn show_completion_popup(
+        &mut self,
+        ui: &mut egui::Ui,
+        cursor_byte: Option<usize>,
+        anchor: Option<egui::Pos2>,
+    ) {
+        if !self.lsp_completion_open || self.lsp_completions.is_empty() {
+            return;
+        }
+        // The cursor must still sit in the word the request was made for;
+        // anything else means the list belongs to another spot.
+        let Some(cur) = cursor_byte else {
+            self.close_completion();
+            return;
+        };
+        let cur = cur.min(self.code_text.len());
+        let word_start = lsp::word_start_before(&self.code_text, cur);
+        if word_start > self.lsp_completion_offset || self.lsp_completion_offset > cur {
+            self.close_completion();
+            return;
+        }
+        let shown = self.completion_filtered(cur);
+        if shown.is_empty() {
+            return;
+        }
+        self.lsp_completion_selected = self.lsp_completion_selected.min(shown.len() - 1);
+        // No cursor, no popup: falling back to a corner rect is how the
+        // list ends up stranded at top-left after focus loss.
+        let Some(anchor) = anchor else {
+            self.close_completion();
+            return;
+        };
+        let mut pick: Option<usize> = None;
+        egui::Window::new("LSP completions")
+            .fixed_pos(anchor)
+            .constrain(true)
+            .title_bar(false)
+            .collapsible(false)
+            .resizable(false)
+            .show(ui, |ui| {
+                ui.set_max_height(220.0);
+                egui::ScrollArea::vertical().show(ui, |ui| {
+                    for (row, &i) in shown.iter().enumerate() {
+                        let item = &self.lsp_completions[i];
+                        let label = if item.detail.is_empty() {
+                            item.label.clone()
+                        } else {
+                            format!("{} — {}", item.label, item.detail)
+                        };
+                        let resp = ui.selectable_label(row == self.lsp_completion_selected, &label);
+                        if row == self.lsp_completion_selected {
+                            ui.scroll_to_rect(resp.rect, None);
+                        }
+                        if resp.clicked() {
+                            pick = Some(row);
+                        }
+                    }
+                });
+            });
+        if let Some(row) = pick {
+            self.lsp_completion_selected = row;
+            self.accept_completion(ui.ctx(), cursor_byte);
+        }
+    }
+}
diff --git a/pite-editor/src/app/inspector.rs b/pite-editor/src/app/inspector.rs
new file mode 100644
index 0000000..76d7263
--- /dev/null
+++ b/pite-editor/src/app/inspector.rs
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use eframe::egui;
+use pite_core::{NodeId, PropValue};
+
+use crate::ops;
+
+use super::EditorApp;
+
+impl EditorApp {
+    pub(super) fn set_prop(&mut self, id: &NodeId, key: &str, value: PropValue) {
+        let result = self
+            .session
+            .host()
+            .with_tree_mut(|t| ops::set_prop(t, id, key, value));
+        match result {
+            Ok(()) => self.viewport_dirty = true,
+            Err(e) => self.log(format!("set prop failed: {e:#}")),
+        }
+    }
+
+    pub(super) fn show_inspector(&mut self, ui: &mut egui::Ui, id: &str) {
+        let node_id = NodeId::from(id.to_string());
+        let snapshot = self.session.host().with_tree(|t| t.get(&node_id).cloned());
+        let Some(node) = snapshot else {
+            ui.label("Node no longer exists.");
+            return;
+        };
+        ui.label(format!("{} ({})", node.name, node.type_name));
+        let mut keys: Vec<String> = node.props.0.keys().cloned().collect();
+        keys.sort();
+        for key in keys {
+            let value = node
+                .props
+                .get(&key)
+                .cloned()
+                .unwrap_or(PropValue::Str(String::new()));
+            match value {
+                PropValue::Num(f) => {
+                    let mut v = f;
+                    ui.horizontal(|ui| {
+                        ui.label(&key);
+                        if ui.add(egui::DragValue::new(&mut v).speed(0.1)).changed() {
+                            self.set_prop(&node_id, &key, PropValue::Num(v));
+                        }
+                    });
+                }
+                PropValue::Int(i) => {
+                    let mut v = i;
+                    ui.horizontal(|ui| {
+                        ui.label(&key);
+                        if ui.add(egui::DragValue::new(&mut v)).changed() {
+                            self.set_prop(&node_id, &key, PropValue::Int(v));
+                        }
+                    });
+                }
+                PropValue::Str(s) => {
+                    let mut v = s;
+                    ui.horizontal(|ui| {
+                        ui.label(&key);
+                        if ui.text_edit_singleline(&mut v).changed() {
+                            self.set_prop(&node_id, &key, PropValue::Str(v));
+                        }
+                    });
+                }
+                PropValue::Bool(b) => {
+                    let mut v = b;
+                    ui.horizontal(|ui| {
+                        ui.label(&key);
+                        if ui.checkbox(&mut v, "").changed() {
+                            self.set_prop(&node_id, &key, PropValue::Bool(v));
+                        }
+                    });
+                }
+                PropValue::Vec2(x, y) => {
+                    let mut v = (x, y);
+                    ui.horizontal(|ui| {
+                        ui.label(&key);
+                        if ui.add(egui::DragValue::new(&mut v.0).speed(1.0)).changed()
+                            || ui.add(egui::DragValue::new(&mut v.1).speed(1.0)).changed()
+                        {
+                            self.set_prop(&node_id, &key, PropValue::Vec2(v.0, v.1));
+                        }
+                    });
+                }
+            }
+        }
+        match &node.script {
+            Some(script) => {
+                ui.label(format!("script: {} ({})", script.path, script.class_name));
+                let script_path = script.path.clone();
+                if ui.button("Open script").clicked() {
+                    let resolved = self.resolve_res(&script_path);
+                    self.open_asset(&resolved);
+                }
+            }
+            None => {
+                ui.label("no script attached.");
+            }
+        }
+    }
+}
diff --git a/pite-editor/src/app/mod.rs b/pite-editor/src/app/mod.rs
new file mode 100644
index 0000000..6f6926e
--- /dev/null
+++ b/pite-editor/src/app/mod.rs
@@ -0,0 +1,504 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+mod assets;
+mod code;
+mod inspector;
+mod scene;
+mod settings;
+#[cfg(test)]
+mod tests;
+mod tree;
+mod viewport;
+
+use std::collections::HashSet;
+use std::path::{Path, PathBuf};
+use std::sync::mpsc::Receiver;
+use std::time::Instant;
+
+use anyhow::Result;
+use eframe::egui;
+use pite_core::NodeId;
+use pite_render::OffscreenRenderer;
+use pite_runtime::GameSession;
+
+use crate::icons::{self, Icon};
+use crate::lsp::{self, LspClient, LspOutcome};
+use crate::ops;
+
+use settings::SettingsDraft;
+
+#[derive(Clone, Copy, PartialEq)]
+pub(crate) enum Tab {
+    Viewport,
+    Code,
+}
+
+pub fn launch(scene: &Path) -> Result<()> {
+    let app = EditorApp::new(scene)?;
+    let options = eframe::NativeOptions {
+        viewport: egui::ViewportBuilder::default()
+            .with_inner_size([1280.0, 800.0])
+            .with_maximized(true)
+            .with_icon(
+                eframe::icon_data::from_png_bytes(include_bytes!("../../../assets/icon.png"))
+                    .expect("assets/icon.png must be a valid PNG"),
+            ),
+        ..Default::default()
+    };
+    eframe::run_native(
+        "Pite Editor",
+        options,
+        Box::new(|cc| {
+            crate::theme::apply(&cc.egui_ctx);
+            Ok(Box::new(app) as Box<dyn eframe::App>)
+        }),
+    )
+    .map_err(|e| anyhow::anyhow!("editor failed: {e}"))?;
+    Ok(())
+}
+
+pub struct EditorApp {
+    pub(super) session: GameSession,
+    pub(super) scene_path: PathBuf,
+    pub(super) project_dir: Option<PathBuf>,
+    pub(super) selected: Option<String>,
+    pub(super) console: Vec<String>,
+    pub(super) seen_errors: HashSet<String>,
+    pub(super) code_file: Option<PathBuf>,
+    pub(super) code_text: String,
+    pub(super) lsp: Option<LspClient>,
+    pub(super) lsp_starter: Option<Receiver<LspOutcome>>,
+    pub(super) lsp_status: String,
+    pub(super) lsp_hint: String,
+    pub(super) lsp_completions: Vec<lsp::CompletionItem>,
+    pub(super) lsp_completion_open: bool,
+    pub(super) lsp_completion_offset: usize,
+    pub(super) lsp_completion_pending: Vec<(i64, usize)>,
+    pub(super) lsp_completion_selected: usize,
+    /// Previous frame's galley row tops (galley space) for the code editor:
+    /// pixel-snapped, so the gutter tiles exactly instead of drifting on an
+    /// assumed pitch. Empty until the first paint.
+    pub(super) code_row_tops: Vec<f32>,
+    /// `galley_pos.y - widget_top.y`: scroll-invariant content offset of the
+    /// galley origin, paired with `code_row_tops`.
+    pub(super) code_galley_dy: f32,
+    pub(super) playing: bool,
+    pub(super) last_frame: Instant,
+    pub(super) add_open: bool,
+    pub(super) add_type: String,
+    pub(super) add_name: String,
+    pub(super) settings: Option<SettingsDraft>,
+    pub(super) open_nodes: HashSet<String>,
+    pub(super) open_seen: HashSet<String>,
+    pub(super) viewport: Option<OffscreenRenderer>,
+    pub(super) viewport_failed: bool,
+    pub(super) viewport_tex: Option<egui::TextureHandle>,
+    pub(super) viewport_dirty: bool,
+    /// Pointer was over the viewport last frame: game input goes to the
+    /// running scene only then, so editing text and shortcuts keep priority.
+    pub(super) viewport_hovered: bool,
+    pub(super) viewport_rect: Option<egui::Rect>,
+    /// Bound to the project's window size: the viewport must frame the scene the
+    /// way the game window does.
+    pub(super) view_size: (u32, u32),
+    pub(super) grip_hover: Option<String>,
+    pub(super) tab: Tab,
+    pub(super) recent: Vec<PathBuf>,
+    pub(super) about_open: bool,
+}
+
+impl EditorApp {
+    pub fn new(scene: &Path) -> Result<Self> {
+        let session = GameSession::open(scene, false)?;
+        let project_dir = pite_project::find_project_root(scene);
+        let view_size = project_dir
+            .as_deref()
+            .and_then(|dir| pite_project::load_manifest(dir).ok())
+            .map_or_else(
+                || {
+                    let d = pite_project::ProjectMeta::default();
+                    (d.window_width, d.window_height)
+                },
+                |m| (m.project.window_width, m.project.window_height),
+            );
+        Ok(Self {
+            session,
+            scene_path: scene.to_path_buf(),
+            project_dir,
+            selected: None,
+            console: vec!["Pite editor ready.".to_string()],
+            seen_errors: HashSet::new(),
+            code_file: None,
+            code_text: String::new(),
+            lsp: None,
+            lsp_starter: None,
+            lsp_status: "lsp: off".to_string(),
+            lsp_hint: String::new(),
+            lsp_completions: Vec::new(),
+            lsp_completion_open: false,
+            lsp_completion_offset: 0,
+            lsp_completion_pending: Vec::new(),
+            lsp_completion_selected: 0,
+            code_row_tops: Vec::new(),
+            code_galley_dy: 0.0,
+            playing: false,
+            last_frame: Instant::now(),
+            add_open: false,
+            add_type: "Node2D".to_string(),
+            add_name: "NewNode".to_string(),
+            settings: None,
+            open_nodes: HashSet::new(),
+            open_seen: HashSet::new(),
+            viewport: None,
+            viewport_failed: false,
+            viewport_tex: None,
+            viewport_hovered: false,
+            viewport_rect: None,
+            view_size,
+            viewport_dirty: true,
+            grip_hover: None,
+            tab: Tab::Viewport,
+            recent: Self::load_recent(),
+            about_open: false,
+        })
+    }
+
+    pub(super) fn log(&mut self, line: impl Into<String>) {
+        self.console.push(line.into());
+        if self.console.len() > 500 {
+            self.console.drain(..self.console.len() - 500);
+        }
+    }
+
+    pub(super) fn drain_script_errors(&mut self) {
+        for err in self.session.errors() {
+            if self.seen_errors.insert(err.clone()) {
+                self.log(err);
+            }
+        }
+    }
+
+    pub(super) fn is_open(&mut self, id: &str) -> bool {
+        if !self.open_seen.contains(id) {
+            self.open_seen.insert(id.to_string());
+            self.open_nodes.insert(id.to_string());
+            return true;
+        }
+        self.open_nodes.contains(id)
+    }
+
+    pub(super) fn debug_info(&mut self, ctx: &egui::Context) {
+        let lines = [
+            format!("pite {}", env!("CARGO_PKG_VERSION")),
+            format!("scene {}", self.scene_path.display()),
+            format!(
+                "project {}",
+                self.project_dir
+                    .as_deref()
+                    .map(|p| p.display().to_string())
+                    .unwrap_or_else(|| "-".to_string())
+            ),
+            format!("lsp {}", self.lsp_status),
+        ];
+        for line in &lines {
+            self.log(line.clone());
+        }
+        ctx.copy_text(lines.join("\n"));
+        self.log("debug info copied to clipboard.".to_string());
+    }
+}
+
+impl eframe::App for EditorApp {
+    fn logic(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
+        let save_shortcut = ctx.input(|i| i.modifiers.command && i.key_pressed(egui::Key::S));
+        if save_shortcut {
+            self.save_scene();
+        }
+        let cmd = |key: egui::Key| {
+            ctx.input(|i| i.modifiers.command && !i.modifiers.shift && i.key_pressed(key))
+        };
+        let cmd_shift = |key: egui::Key| {
+            ctx.input(|i| i.modifiers.command && i.modifiers.shift && i.key_pressed(key))
+        };
+        if cmd(egui::Key::N) {
+            self.new_scene_via_dialog();
+        }
+        if cmd(egui::Key::O) {
+            self.open_scene_via_dialog();
+        }
+        if cmd_shift(egui::Key::S) {
+            self.save_scene_as_via_dialog();
+        }
+        if cmd(egui::Key::Q) {
+            ctx.send_viewport_cmd(egui::ViewportCommand::Close);
+        }
+        if self.playing {
+            let delta = self.last_frame.elapsed().as_secs_f64().min(0.1);
+            self.last_frame = Instant::now();
+            self.pump_game_input(ctx);
+            self.session.frame(delta);
+            self.drain_script_errors();
+            ctx.request_repaint();
+        }
+    }
+
+    fn ui(&mut self, ui: &mut egui::Ui, _frame: &mut eframe::Frame) {
+        let ctx = ui.ctx().clone();
+
+        egui::Panel::top("menu").show(ui, |ui| {
+            // Everything lives inside the MenuBar scope: MenuBar claims the
+            // full row width, so siblings after it in an outer horizontal
+            // row get zero space and vanish.
+            egui::MenuBar::new().ui(ui, |ui| {
+                ui.menu_button("Scene", |ui| {
+                    if ui.button("New Scene  Ctrl+N").clicked() {
+                        self.new_scene_via_dialog();
+                        ui.close();
+                    }
+                    if ui.button("Open Scene…  Ctrl+O").clicked() {
+                        self.open_scene_via_dialog();
+                        ui.close();
+                    }
+                    if self.recent.is_empty() {
+                        ui.add_enabled(false, egui::Button::new("Open Recent"));
+                    } else {
+                        ui.menu_button("Open Recent", |ui| {
+                            let recent = self.recent.clone();
+                            for path in &recent {
+                                if ui.button(path.display().to_string()).clicked() {
+                                    let path = path.clone();
+                                    self.open_scene_file(&path);
+                                    ui.close();
+                                }
+                            }
+                        });
+                    }
+                    ui.separator();
+                    if ui.button("Save Scene  Ctrl+S").clicked() {
+                        self.save_scene();
+                        ui.close();
+                    }
+                    if ui.button("Save Scene As…  Ctrl+Shift+S").clicked() {
+                        self.save_scene_as_via_dialog();
+                        ui.close();
+                    }
+                    ui.separator();
+                    if ui.button("Quit  Ctrl+Q").clicked() {
+                        ctx.send_viewport_cmd(egui::ViewportCommand::Close);
+                    }
+                });
+                ui.menu_button("Project", |ui| {
+                    if ui.button("Project Settings…").clicked() {
+                        self.open_settings();
+                        ui.close();
+                    }
+                });
+                ui.menu_button("Help", |ui| {
+                    if ui.button("Repository").clicked() {
+                        ctx.open_url(egui::OpenUrl::new_tab("https://github.com/piteengine/pite"));
+                    }
+                    if ui.button("Issues").clicked() {
+                        ctx.open_url(egui::OpenUrl::new_tab(
+                            "https://github.com/piteengine/pite/issues",
+                        ));
+                    }
+                    ui.separator();
+                    if ui.button("About Pite").clicked() {
+                        self.about_open = true;
+                        ui.close();
+                    }
+                    if ui.button("Copy Debug Info").clicked() {
+                        self.debug_info(ui.ctx());
+                        ui.close();
+                    }
+                });
+                // Transport controls pinned to the right end, Godot-style:
+                // the same actions as the Run menu, always visible.
+                // Right-to-left places the first widget rightmost, so Stop
+                // comes first to keep the Play, Stop order.
+                let (play_icon, play_tip) = if self.playing {
+                    (Icon::Pause, "Pause the scene")
+                } else {
+                    (Icon::Play, "Run the scene")
+                };
+                ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
+                    if icons::icon_button(ui, Icon::Stop, "Stop and reset the scene").clicked() {
+                        self.stop();
+                    }
+                    if icons::icon_button(ui, play_icon, play_tip).clicked() {
+                        self.toggle_play();
+                    }
+                });
+            });
+        });
+
+        if self.about_open {
+            egui::Window::new("About Pite")
+                .open(&mut self.about_open)
+                .show(ui, |ui| {
+                    ui.label(format!("Pite game engine {}", env!("CARGO_PKG_VERSION")));
+                    ui.label("Scene-tree 2D engine: Rust core, embedded Python, egui editor.");
+                    ui.horizontal(|ui| {
+                        if ui.button("Repository").clicked() {
+                            ui.ctx().open_url(egui::OpenUrl::new_tab(
+                                "https://github.com/piteengine/pite",
+                            ));
+                        }
+                        if ui.button("Issues").clicked() {
+                            ui.ctx().open_url(egui::OpenUrl::new_tab(
+                                "https://github.com/piteengine/pite/issues",
+                            ));
+                        }
+                    });
+                });
+        }
+
+        egui::Panel::left("left")
+            .default_size(240.0)
+            .min_size(240.0)
+            .max_size(360.0)
+            .resizable(true)
+            .show(ui, |ui| {
+                ui.horizontal(|ui| {
+                    ui.heading("Scene");
+                    if icons::icon_button(ui, Icon::Add, "Add a child node under the selection")
+                        .clicked()
+                    {
+                        self.add_open = true;
+                    }
+                });
+                if self.add_open {
+                    self.show_add_child(ui);
+                }
+                let tree_h = (ui.available_height() * 0.52).max(120.0);
+                egui::ScrollArea::vertical()
+                    .id_salt("tree")
+                    .max_height(tree_h)
+                    .show(ui, |ui| {
+                        let root = self.session.host().with_tree(|t| t.root().cloned());
+                        if let Some(root) = root {
+                            self.show_node(ui, &root);
+                        }
+                        let avail = ui.available_size();
+                        if avail.y > 8.0 {
+                            let (rect, resp) = ui.allocate_exact_size(
+                                egui::vec2(avail.x.max(1.0), avail.y),
+                                egui::Sense::hover(),
+                            );
+                            if egui::DragAndDrop::has_any_payload(ui.ctx())
+                                && resp.contains_pointer()
+                            {
+                                ui.painter().rect_stroke(
+                                    rect,
+                                    3.0,
+                                    egui::Stroke::new(1.5_f32, crate::theme::FAINT),
+                                    egui::StrokeKind::Middle,
+                                );
+                            }
+                            if let Some(dragged) = resp.dnd_release_payload::<String>() {
+                                if let Some(root) =
+                                    self.session.host().with_tree(|t| t.root().cloned())
+                                {
+                                    let dragged_id = NodeId::from(dragged.as_str());
+                                    let result = self.session.host().with_tree_mut(|t| {
+                                        let len = t.children_of(&root).len();
+                                        ops::place_node(t, &dragged_id, &root, len)
+                                    });
+                                    match result {
+                                        Ok(()) => {
+                                            self.viewport_dirty = true;
+                                            self.log(format!("moved {dragged_id}."));
+                                        }
+                                        Err(e) => self.log(format!("move failed: {e:#}")),
+                                    }
+                                }
+                            }
+                        }
+                    });
+                ui.separator();
+                ui.heading("Assets");
+                let rels = self.asset_rel_paths();
+                let refs: Vec<&str> = rels.iter().map(String::as_str).collect();
+                let root = self
+                    .project_dir
+                    .clone()
+                    .unwrap_or_else(|| PathBuf::from("."));
+                egui::ScrollArea::new([true, true])
+                    .id_salt("assets")
+                    .auto_shrink([false, false])
+                    .show(ui, |ui| {
+                        self.show_asset_dir(ui, &root, "", &refs);
+                    });
+            });
+
+        egui::Panel::right("inspector")
+            .default_size(240.0)
+            .min_size(240.0)
+            .max_size(360.0)
+            .resizable(true)
+            .show(ui, |ui| {
+                egui::ScrollArea::vertical()
+                    .id_salt("inspector")
+                    .auto_shrink([false, false])
+                    .show(ui, |ui| {
+                        ui.heading("Inspector");
+                        match self.selected.clone() {
+                            Some(id) => self.show_inspector(ui, &id),
+                            None => {
+                                ui.label("Select a node.");
+                            }
+                        }
+                    })
+            });
+
+        egui::Panel::bottom("console")
+            .default_size(120.0)
+            .min_size(120.0)
+            .max_size(240.0)
+            .resizable(true)
+            .show(ui, |ui| {
+                ui.heading("Console");
+                egui::ScrollArea::vertical()
+                    .id_salt("console")
+                    .auto_shrink([false, false])
+                    .stick_to_bottom(true)
+                    .show(ui, |ui| {
+                        for line in &self.console {
+                            ui.monospace(line);
+                        }
+                    });
+            });
+
+        egui::CentralPanel::default().show(ui, |ui| {
+            ui.horizontal(|ui| {
+                ui.selectable_value(&mut self.tab, Tab::Viewport, "Viewport");
+                ui.selectable_value(&mut self.tab, Tab::Code, "Code");
+            });
+            ui.separator();
+            ui.horizontal(|ui| match self.tab {
+                Tab::Viewport => {
+                    ui.label(self.scene_path.to_string_lossy().as_ref());
+                    if icons::icon_button(ui, Icon::Save, "Save scene (Ctrl+S)").clicked() {
+                        self.save_scene();
+                    }
+                }
+                Tab::Code => {
+                    if let Some(file) = self.code_file.clone() {
+                        ui.label(file.to_string_lossy().as_ref());
+                        if icons::icon_button(ui, Icon::Save, "Save script (Ctrl+S)").clicked() {
+                            self.save_code();
+                        }
+                    } else {
+                        ui.label("Open a .py file from Assets.");
+                    }
+                }
+            });
+            ui.separator();
+            match self.tab {
+                Tab::Viewport => self.show_viewport(ui),
+                Tab::Code => self.show_code(ui),
+            }
+        });
+
+        self.show_settings(&ctx);
+    }
+}
diff --git a/pite-editor/src/app/scene.rs b/pite-editor/src/app/scene.rs
new file mode 100644
index 0000000..a5d82ca
--- /dev/null
+++ b/pite-editor/src/app/scene.rs
@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use std::path::{Path, PathBuf};
+
+use pite_runtime::GameSession;
+
+use crate::ops;
+
+use super::{EditorApp, Tab};
+
+impl EditorApp {
+    pub(super) fn save_scene(&mut self) {
+        let source = match std::fs::metadata(&self.scene_path) {
+            Ok(_) => match pite_scene::load_scene(&self.scene_path) {
+                Ok(doc) => Some(doc),
+                Err(e) => {
+                    self.log(format!(
+                        "save aborted: cannot read existing scene {}: {e:#}",
+                        self.scene_path.display()
+                    ));
+                    return;
+                }
+            },
+            Err(_) => None,
+        };
+        let scene_dir = self
+            .scene_path
+            .parent()
+            .map(Path::to_path_buf)
+            .unwrap_or_else(|| PathBuf::from("."));
+        let refs = ops::InstanceRefs {
+            scene_dir: &scene_dir,
+            project_dir: self.project_dir.as_deref(),
+        };
+        let built = self
+            .session
+            .host()
+            .with_tree(|tree| ops::build_doc(tree, source.as_ref(), Some(refs)));
+        match built.and_then(|doc| pite_scene::save_scene(&doc).map_err(anyhow::Error::from)) {
+            Ok(text) => match ops::save_text(&self.scene_path, &text) {
+                Ok(()) => {
+                    self.viewport_dirty = true;
+                    self.log(format!("saved scene {}", self.scene_path.display()));
+                }
+                Err(e) => self.log(format!("save scene failed: {e:#}")),
+            },
+            Err(e) => self.log(format!("save scene failed: {e:#}")),
+        }
+    }
+
+    pub(super) fn view_size_for(project_dir: Option<&Path>) -> (u32, u32) {
+        project_dir
+            .and_then(|dir| pite_project::load_manifest(dir).ok())
+            .map_or_else(
+                || {
+                    let d = pite_project::ProjectMeta::default();
+                    (d.window_width, d.window_height)
+                },
+                |m| (m.project.window_width, m.project.window_height),
+            )
+    }
+
+    pub(super) fn recent_file() -> Option<PathBuf> {
+        let base = std::env::var_os("XDG_CONFIG_HOME")
+            .map(PathBuf::from)
+            .filter(|p| !p.as_os_str().is_empty())
+            .or_else(|| std::env::var_os("HOME").map(|h| PathBuf::from(h).join(".config")))?;
+        Some(base.join("pite").join("recent.json"))
+    }
+
+    pub(super) fn read_recent_file(path: &Path) -> Vec<PathBuf> {
+        let text = std::fs::read_to_string(path).unwrap_or_default();
+        let files: Vec<String> = serde_json::from_str(&text).unwrap_or_default();
+        files
+            .into_iter()
+            .map(PathBuf::from)
+            .filter(|p| p.is_file())
+            .collect()
+    }
+
+    pub(super) fn write_recent_file(path: &Path, recent: &[PathBuf]) -> anyhow::Result<()> {
+        if let Some(parent) = path.parent() {
+            std::fs::create_dir_all(parent)?;
+        }
+        let files: Vec<String> = recent
+            .iter()
+            .map(|p| p.to_string_lossy().into_owned())
+            .collect();
+        std::fs::write(path, serde_json::to_string_pretty(&files)?)?;
+        Ok(())
+    }
+
+    pub(super) fn load_recent() -> Vec<PathBuf> {
+        Self::recent_file()
+            .map(|p| Self::read_recent_file(&p))
+            .unwrap_or_default()
+    }
+
+    pub(super) fn push_recent(&mut self, file: &Path) {
+        self.recent.retain(|p| p != file);
+        self.recent.insert(0, file.to_path_buf());
+        self.recent.truncate(10);
+        if let Some(path) = Self::recent_file() {
+            if let Err(e) = Self::write_recent_file(&path, &self.recent) {
+                self.log(format!("recent list not saved: {e:#}"));
+            }
+        }
+    }
+
+    /// Root-only scene: `New Scene` starts blank, never from the example scaffold.
+    pub(super) fn blank_scene_text() -> String {
+        format!(
+            "format_version = {}\nroot = \"root\"\n\n[[node]]\nid = \"root\"\ntype = \"Node2D\"\nname = \"Main\"\n",
+            pite_scene::FORMAT_VERSION
+        )
+    }
+
+    pub(super) fn open_scene_file(&mut self, file: &Path) {
+        match GameSession::open(file, false) {
+            Ok(session) => {
+                self.session = session;
+                self.scene_path = file.to_path_buf();
+                self.project_dir = pite_project::find_project_root(file);
+                self.view_size = Self::view_size_for(self.project_dir.as_deref());
+                self.selected = None;
+                self.viewport_dirty = true;
+                self.tab = Tab::Viewport;
+                self.push_recent(file);
+                self.log(format!("opened {}", file.display()));
+            }
+            Err(e) => self.log(format!("open failed: {e:#}")),
+        }
+    }
+
+    /// Native dialogs return the path as-is: enforce `.ptscn` so a bare
+    /// name cannot scatter extensionless scenes through the project.
+    pub(super) fn with_scene_extension(mut path: PathBuf) -> PathBuf {
+        if path.extension().and_then(|e| e.to_str()) != Some("ptscn") {
+            path.set_extension("ptscn");
+        }
+        path
+    }
+
+    pub(super) fn new_scene_via_dialog(&mut self) {
+        let Some(path) = rfd::FileDialog::new()
+            .add_filter("Pite scene", &["ptscn"])
+            .set_file_name("main.ptscn")
+            .save_file()
+        else {
+            return;
+        };
+        let path = Self::with_scene_extension(path);
+        match std::fs::write(&path, Self::blank_scene_text()) {
+            Ok(()) => self.open_scene_file(&path),
+            Err(e) => self.log(format!("new scene failed: {e:#}")),
+        }
+    }
+
+    pub(super) fn open_scene_via_dialog(&mut self) {
+        let Some(path) = rfd::FileDialog::new()
+            .add_filter("Pite scene", &["ptscn"])
+            .pick_file()
+        else {
+            return;
+        };
+        self.open_scene_file(&path);
+    }
+
+    pub(super) fn save_scene_as_via_dialog(&mut self) {
+        let Some(path) = rfd::FileDialog::new()
+            .add_filter("Pite scene", &["ptscn"])
+            .set_file_name(
+                self.scene_path
+                    .file_name()
+                    .and_then(|s| s.to_str())
+                    .unwrap_or("main.ptscn"),
+            )
+            .save_file()
+        else {
+            return;
+        };
+        self.scene_path = Self::with_scene_extension(path);
+        self.save_scene();
+        let path = self.scene_path.clone();
+        self.push_recent(&path);
+    }
+}
diff --git a/pite-editor/src/app/settings.rs b/pite-editor/src/app/settings.rs
new file mode 100644
index 0000000..0c9c563
--- /dev/null
+++ b/pite-editor/src/app/settings.rs
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use std::path::PathBuf;
+
+use eframe::egui;
+
+use super::EditorApp;
+
+/// Unsaved Project Settings edits. `None` while the window is closed; `base`
+/// carries the unknown keys so saving only swaps the known fields.
+pub(crate) struct SettingsDraft {
+    pub(crate) base: pite_project::PiteManifest,
+    pub(crate) name: String,
+    pub(crate) author: String,
+    pub(crate) main_scene: String,
+    pub(crate) python: String,
+    pub(crate) icon: String,
+    pub(crate) width: String,
+    pub(crate) height: String,
+    pub(crate) binary_name: String,
+    pub(crate) include: String,
+    pub(crate) error: String,
+}
+
+impl EditorApp {
+    pub(super) fn open_settings(&mut self) {
+        let dir = match self.project_dir.clone() {
+            Some(dir) => dir,
+            None => {
+                self.log("project settings: no project open.");
+                return;
+            }
+        };
+        match pite_project::load_manifest(&dir) {
+            Ok(base) => {
+                let binary_name = base.export.binary_name.clone().unwrap_or_default();
+                let include = base.export.include.join("\n");
+                let project = &base.project;
+                self.settings = Some(SettingsDraft {
+                    name: project.name.clone(),
+                    author: project.author.clone(),
+                    main_scene: project.main_scene.clone(),
+                    python: project.python.clone(),
+                    icon: project.icon.clone(),
+                    width: project.window_width.to_string(),
+                    height: project.window_height.to_string(),
+                    binary_name,
+                    include,
+                    error: String::new(),
+                    base,
+                });
+            }
+            Err(e) => self.log(format!("project settings: cannot load manifest: {e:#}")),
+        }
+    }
+
+    pub(super) fn save_settings(&mut self) {
+        let (manifest, dir) = {
+            let draft = match self.settings.as_mut() {
+                Some(draft) => draft,
+                None => return,
+            };
+            let width = match draft.width.trim().parse::<u32>() {
+                Ok(width) => width,
+                Err(_) => {
+                    draft.error = format!("window width {:?} is not a number", draft.width);
+                    return;
+                }
+            };
+            let height = match draft.height.trim().parse::<u32>() {
+                Ok(height) => height,
+                Err(_) => {
+                    draft.error = format!("window height {:?} is not a number", draft.height);
+                    return;
+                }
+            };
+            let mut manifest = draft.base.clone();
+            let project = &mut manifest.project;
+            project.name = draft.name.clone();
+            project.author = draft.author.clone();
+            project.main_scene = draft.main_scene.clone();
+            project.python = draft.python.clone();
+            project.icon = draft.icon.clone();
+            project.window_width = width;
+            project.window_height = height;
+            let binary_name = draft.binary_name.trim().to_string();
+            manifest.export.binary_name = if binary_name.is_empty() {
+                None
+            } else {
+                Some(binary_name)
+            };
+            manifest.export.include = draft
+                .include
+                .lines()
+                .map(str::trim)
+                .filter(|line| !line.is_empty())
+                .map(str::to_string)
+                .collect();
+            let (errors, _) = pite_project::validate_manifest(&manifest);
+            if !errors.is_empty() {
+                draft.error = errors.join("\n");
+                return;
+            }
+            (
+                manifest,
+                self.project_dir
+                    .clone()
+                    .unwrap_or_else(|| PathBuf::from(".")),
+            )
+        };
+        match pite_project::save_manifest(&dir, &manifest) {
+            Ok(()) => {
+                self.view_size = (
+                    manifest.project.window_width,
+                    manifest.project.window_height,
+                );
+                self.viewport_dirty = true;
+                self.settings = None;
+                self.log("saved project settings.");
+            }
+            Err(e) => match self.settings.as_mut() {
+                Some(draft) => draft.error = format!("{e:#}"),
+                None => self.log(format!("save project settings failed: {e:#}")),
+            },
+        }
+    }
+
+    pub(super) fn show_settings(&mut self, ctx: &egui::Context) {
+        let mut open = self.settings.is_some();
+        egui::Window::new("Project Settings")
+            .open(&mut open)
+            .show(ctx, |ui| {
+                let Some(draft) = self.settings.as_mut() else {
+                    return;
+                };
+                ui.label(format!(
+                    "engine version: {}",
+                    draft.base.project.pite_version
+                ));
+                ui.separator();
+                egui::Grid::new("settings-grid")
+                    .num_columns(2)
+                    .show(ui, |ui| {
+                        ui.label("Name");
+                        ui.text_edit_singleline(&mut draft.name);
+                        ui.end_row();
+                        ui.label("Author");
+                        ui.text_edit_singleline(&mut draft.author);
+                        ui.end_row();
+                        ui.label("Main scene");
+                        ui.text_edit_singleline(&mut draft.main_scene);
+                        ui.end_row();
+                        ui.label("Python");
+                        ui.text_edit_singleline(&mut draft.python);
+                        ui.end_row();
+                        ui.label("Icon");
+                        ui.text_edit_singleline(&mut draft.icon);
+                        ui.end_row();
+                        ui.label("Window width");
+                        ui.text_edit_singleline(&mut draft.width);
+                        ui.end_row();
+                        ui.label("Window height");
+                        ui.text_edit_singleline(&mut draft.height);
+                        ui.end_row();
+                    });
+                ui.separator();
+                ui.heading("Export");
+                egui::Grid::new("settings-export-grid")
+                    .num_columns(2)
+                    .show(ui, |ui| {
+                        ui.label("Binary name");
+                        ui.text_edit_singleline(&mut draft.binary_name);
+                        ui.end_row();
+                    });
+                ui.label("Extra staged files, one per line:");
+                ui.text_edit_multiline(&mut draft.include);
+                if !draft.error.is_empty() {
+                    ui.label(format!("error: {}", draft.error));
+                }
+                if ui.button("Save").clicked() {
+                    self.save_settings();
+                }
+            });
+        if !open {
+            self.settings = None;
+        }
+    }
+}
diff --git a/pite-editor/src/app/tests.rs b/pite-editor/src/app/tests.rs
new file mode 100644
index 0000000..185d080
--- /dev/null
+++ b/pite-editor/src/app/tests.rs
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use std::path::{Path, PathBuf};
+
+use eframe::egui;
+
+use super::viewport::{fit_view, viewport_cursor};
+use super::*;
+
+#[test]
+fn cursor_maps_viewport_corners() {
+    let rect =
+        egui::Rect::from_min_size(egui::Pos2::new(10.0, 20.0), egui::Vec2::new(400.0, 300.0));
+    assert_eq!(
+        viewport_cursor(rect, (800, 600), egui::Pos2::new(10.0, 20.0)),
+        Some((0.0, 0.0))
+    );
+    assert_eq!(
+        viewport_cursor(rect, (800, 600), egui::Pos2::new(410.0, 320.0)),
+        Some((800.0, 600.0))
+    );
+    assert_eq!(
+        viewport_cursor(rect, (800, 600), egui::Pos2::new(210.0, 170.0)),
+        Some((400.0, 300.0))
+    );
+}
+
+#[test]
+fn cursor_rejects_degenerate_viewport() {
+    let rect = egui::Rect::from_min_size(egui::Pos2::ZERO, egui::Vec2::new(400.0, 300.0));
+    assert_eq!(
+        viewport_cursor(rect, (0, 600), egui::Pos2::new(10.0, 10.0)),
+        None
+    );
+    let flat = egui::Rect::from_min_size(egui::Pos2::ZERO, egui::Vec2::new(0.0, 300.0));
+    assert_eq!(
+        viewport_cursor(flat, (800, 600), egui::Pos2::new(10.0, 10.0)),
+        None
+    );
+}
+
+#[test]
+fn viewport_fits_available_space_on_both_axes() {
+    let view = (800, 600);
+    // Wide panel: height binds, width shrinks to match.
+    let wide = fit_view(egui::Vec2::new(2000.0, 400.0), view);
+    assert!((wide.y - 400.0).abs() < 0.01, "got {wide:?}");
+    assert!((wide.x - 400.0 * 4.0 / 3.0).abs() < 0.01, "got {wide:?}");
+    // Tall panel: width binds, height shrinks to match.
+    let tall = fit_view(egui::Vec2::new(400.0, 2000.0), view);
+    assert!((tall.x - 400.0).abs() < 0.01, "got {tall:?}");
+    assert!((tall.y - 300.0).abs() < 0.01, "got {tall:?}");
+    // Never exceeds the panel on either axis, at any panel shape.
+    for (ax, ay) in [(2000.0, 400.0), (400.0, 2000.0), (800.0, 600.0), (1.0, 1.0)] {
+        let f = fit_view(egui::Vec2::new(ax, ay), view);
+        assert!(
+            f.x <= ax + 0.01 && f.y <= ay + 0.01,
+            "{f:?} exceeds {ax}x{ay}"
+        );
+    }
+    // Degenerate input stays positive.
+    let tiny = fit_view(egui::Vec2::ZERO, view);
+    assert!(tiny.x > 0.0 && tiny.y > 0.0);
+}
+
+#[test]
+fn viewport_is_centered_in_its_panel() {
+    // 4:3 scene, panel wider than tall: fitted box is height-bound and must
+    // sit centered horizontally, with equal margins on both sides.
+    let avail = egui::Vec2::new(1000.0, 300.0);
+    let fitted = fit_view(avail, (800, 600));
+    let outer = egui::Rect::from_min_size(egui::Pos2::ZERO, avail);
+    let view = egui::Rect::from_center_size(outer.center(), fitted);
+    assert!((view.left() - (outer.right() - view.right())).abs() < 0.01);
+    assert!(view.width() <= outer.width() + 0.01);
+    assert!(view.height() <= outer.height() + 0.01);
+}
+
+#[test]
+fn editor_opens_gear_group_as_text() {
+    for name in [
+        "a.py", "p.toml", "c.cfg", "c.ini", "d.json", "e.yaml", "f.yml", "G.TOML",
+    ] {
+        assert!(EditorApp::editor_text_file(Path::new(name)), "{name}");
+    }
+    for name in ["a.png", "b.wav", "c.ptscn", "noext", "a.pyx"] {
+        assert!(!EditorApp::editor_text_file(Path::new(name)), "{name}");
+    }
+}
+
+#[test]
+fn recent_list_round_trips_and_drops_missing() {
+    let dir = std::env::temp_dir().join(format!("pite-recent-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    let present = dir.join("a.ptscn");
+    std::fs::write(&present, "x").unwrap();
+    let file = dir.join("recent.json");
+    let recent = vec![present.clone(), dir.join("gone.ptscn")];
+    EditorApp::write_recent_file(&file, &recent).unwrap();
+    assert_eq!(EditorApp::read_recent_file(&file), vec![present]);
+    std::fs::remove_dir_all(&dir).unwrap();
+}
+
+#[test]
+fn save_dialog_path_keeps_scene_extension() {
+    assert_eq!(
+        EditorApp::with_scene_extension(PathBuf::from("s/main")),
+        PathBuf::from("s/main.ptscn")
+    );
+    assert_eq!(
+        EditorApp::with_scene_extension(PathBuf::from("s/main.ptscn")),
+        PathBuf::from("s/main.ptscn")
+    );
+}
+
+#[test]
+fn blank_scene_tracks_format_version() {
+    let text = EditorApp::blank_scene_text();
+    assert!(
+        text.starts_with(&format!(
+            "format_version = {}\n",
+            pite_scene::FORMAT_VERSION
+        )),
+        "{text}"
+    );
+    assert!(text.contains("id = \"root\""));
+}
diff --git a/pite-editor/src/app/tree.rs b/pite-editor/src/app/tree.rs
new file mode 100644
index 0000000..2a1736c
--- /dev/null
+++ b/pite-editor/src/app/tree.rs
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use eframe::egui;
+use pite_core::NodeId;
+
+use crate::icons::{self, Icon};
+use crate::ops;
+
+use super::EditorApp;
+
+#[derive(Clone, Copy, PartialEq)]
+pub(super) enum DropZone {
+    None,
+    Before,
+    Under,
+}
+
+impl EditorApp {
+    pub(super) fn delete_node(&mut self, id: &NodeId) {
+        match self
+            .session
+            .host()
+            .with_tree_mut(|t| ops::remove_node(t, id))
+        {
+            Ok(()) => {
+                if self.selected.as_deref() == Some(id.as_str()) {
+                    self.selected = None;
+                }
+                self.viewport_dirty = true;
+                self.log(format!("deleted {id}."));
+            }
+            Err(e) => self.log(format!("delete failed: {e:#}")),
+        }
+    }
+
+    pub(super) fn move_sibling(&mut self, id: &NodeId, delta: i32) {
+        match self
+            .session
+            .host()
+            .with_tree_mut(|t| ops::move_sibling(t, id, delta))
+        {
+            Ok(()) => {
+                self.viewport_dirty = true;
+                self.log(format!("moved {id}."));
+            }
+            Err(e) => self.log(format!("move failed: {e:#}")),
+        }
+    }
+
+    pub(super) fn drop_node(&mut self, dragged: &str, target: &NodeId, zone: DropZone) {
+        let dragged_id = NodeId::from(dragged);
+        if dragged_id == *target || zone == DropZone::None {
+            return;
+        }
+        let result = self.session.host().with_tree_mut(|t| match zone {
+            DropZone::Under => ops::move_node(t, &dragged_id, Some(target.clone())),
+            DropZone::Before => {
+                let parent = t
+                    .get(target)
+                    .and_then(|n| n.parent.clone())
+                    .ok_or_else(|| anyhow::anyhow!("cannot reorder at the top level"))?;
+                let sibs = t.children_of(&parent);
+                let pos = sibs
+                    .iter()
+                    .position(|s| s == target)
+                    .ok_or_else(|| anyhow::anyhow!("target `{target}` not found"))?;
+                ops::place_node(t, &dragged_id, &parent, pos)
+            }
+            DropZone::None => Ok(()),
+        });
+        match result {
+            Ok(()) => {
+                self.viewport_dirty = true;
+                self.log(format!("moved {dragged_id}."));
+            }
+            Err(e) => self.log(format!("move failed: {e:#}")),
+        }
+    }
+
+    pub(super) fn show_add_child(&mut self, ui: &mut egui::Ui) {
+        ui.separator();
+        let types = ops::registered_types();
+        if !types.contains(&self.add_type) {
+            self.add_type = types.first().cloned().unwrap_or_default();
+        }
+        egui::ComboBox::from_label("Type")
+            .selected_text(&self.add_type)
+            .show_ui(ui, |ui| {
+                for t in &types {
+                    ui.selectable_value(&mut self.add_type, t.clone(), t);
+                }
+            });
+        ui.text_edit_singleline(&mut self.add_name);
+        ui.horizontal(|ui| {
+            if ui.button("Add").clicked() {
+                let type_name = self.add_type.clone();
+                let name = self.add_name.clone();
+                let parent = self
+                    .selected
+                    .clone()
+                    .map(NodeId::from)
+                    .or_else(|| self.session.host().with_tree(|t| t.root().cloned()));
+                match self
+                    .session
+                    .host()
+                    .with_tree_mut(|t| ops::add_node(t, parent, &type_name, &name))
+                {
+                    Ok(id) => {
+                        self.selected = Some(id.to_string());
+                        self.add_open = false;
+                        self.viewport_dirty = true;
+                        self.log(format!("added {id} ({type_name})."));
+                    }
+                    Err(e) => self.log(format!("add node failed: {e:#}")),
+                }
+            }
+            if ui.button("Cancel").clicked() {
+                self.add_open = false;
+            }
+        });
+    }
+
+    pub(super) fn show_node(&mut self, ui: &mut egui::Ui, id: &NodeId) {
+        let (name, type_name, children) = self
+            .session
+            .host()
+            .with_tree(|t| {
+                t.get(id)
+                    .map(|n| (n.name.clone(), n.type_name.clone(), t.children_of(id)))
+            })
+            .unwrap_or_else(|| ("?".to_string(), "?".to_string(), vec![]));
+        let script = self.session.host().with_tree(|t| {
+            t.get(id).and_then(|n| {
+                n.script
+                    .as_ref()
+                    .map(|s| (s.class_name.clone(), self.resolve_res(&s.path)))
+            })
+        });
+        let selected = self.selected.as_ref() == Some(&id.to_string());
+        let id_str = id.to_string();
+        let target = id.clone();
+        let is_root = self.session.host().with_tree(|t| t.root() == Some(id));
+        let open = self.is_open(&id_str);
+        let show_grip = self.grip_hover.as_deref() == Some(id_str.as_str());
+        let mut row_resp: Option<egui::Response> = None;
+        let mut grip_rect: Option<egui::Rect> = None;
+        let hresp = ui.horizontal(|ui| {
+            if !is_root {
+                let g = ui.dnd_drag_source(
+                    egui::Id::new(("tree-grip", id_str.clone())),
+                    id_str.clone(),
+                    |ui| {
+                        ui.allocate_exact_size(
+                            egui::Vec2::new(12.0, ui.text_style_height(&egui::TextStyle::Body)),
+                            egui::Sense::hover(),
+                        )
+                    },
+                );
+                grip_rect = Some(g.inner.0);
+            }
+            let r = ui.selectable_label(selected, format!("{name} ({type_name})"));
+            if let Some((class, file)) = script.as_ref() {
+                let (badge, resp) =
+                    ui.allocate_exact_size(egui::vec2(16.0, 16.0), egui::Sense::click());
+                if ui.is_rect_visible(badge) {
+                    icons::draw_icon(ui.painter(), badge, Icon::Script, crate::theme::FAINT);
+                }
+                let resp = resp.on_hover_text(format!("open {class}"));
+                if resp.clicked() {
+                    let file = file.clone();
+                    self.open_asset(&file);
+                }
+            }
+            if r.clicked() {
+                self.selected = Some(id_str.clone());
+            }
+            if !children.is_empty() && r.double_clicked() {
+                if open {
+                    self.open_nodes.remove(&id_str);
+                } else {
+                    self.open_nodes.insert(id_str.clone());
+                }
+            }
+            let menu_id = id.clone();
+            let menu_open = open;
+            let menu_kids = !children.is_empty();
+            let _ = r.context_menu(|ui| {
+                if ui.button("Delete").clicked() {
+                    self.delete_node(&menu_id);
+                    ui.close();
+                }
+                if ui.button("Move up").clicked() {
+                    self.move_sibling(&menu_id, -1);
+                    ui.close();
+                }
+                if ui.button("Move down").clicked() {
+                    self.move_sibling(&menu_id, 1);
+                    ui.close();
+                }
+                if menu_kids {
+                    let label = if menu_open { "Collapse" } else { "Expand" };
+                    if ui.button(label).clicked() {
+                        if menu_open {
+                            self.open_nodes.remove(&menu_id.to_string());
+                        } else {
+                            self.open_nodes.insert(menu_id.to_string());
+                        }
+                        ui.close();
+                    }
+                }
+            });
+            row_resp = Some(r);
+        });
+        if hresp.response.contains_pointer() {
+            self.grip_hover = Some(id_str.clone());
+        } else if self.grip_hover.as_deref() == Some(id_str.as_str()) {
+            self.grip_hover = None;
+        }
+        if show_grip {
+            if let (Some(g), Some(r)) = (grip_rect, &row_resp) {
+                let p = ui.painter();
+                let x = g.center().x;
+                let y = r.rect.center().y;
+                for row in 0..3 {
+                    for col in 0..2 {
+                        p.circle_filled(
+                            egui::Pos2::new(
+                                x - 2.25 + col as f32 * 4.5,
+                                y - 4.5 + row as f32 * 4.5,
+                            ),
+                            1.2,
+                            crate::theme::FAINT,
+                        );
+                    }
+                }
+            }
+        }
+        if let Some(r) = &row_resp {
+            let dragging = egui::DragAndDrop::has_any_payload(ui.ctx());
+            let zone = if dragging && r.contains_pointer() {
+                let pos = ui.ctx().pointer_hover_pos().unwrap_or(r.rect.center());
+                let frac = (pos.y - r.rect.top()) / r.rect.height().max(1.0);
+                if is_root {
+                    DropZone::Under
+                } else if frac < 0.35 || frac > 0.65 {
+                    DropZone::Before
+                } else {
+                    DropZone::Under
+                }
+            } else {
+                DropZone::None
+            };
+            let p = ui.painter();
+            let edge = egui::Stroke::new(1.5_f32, crate::theme::FAINT);
+            match zone {
+                DropZone::Before => {
+                    p.line_segment(
+                        [
+                            egui::Pos2::new(r.rect.left(), r.rect.top() + 1.0),
+                            egui::Pos2::new(r.rect.right(), r.rect.top() + 1.0),
+                        ],
+                        edge,
+                    );
+                }
+                DropZone::Under => {
+                    p.rect_stroke(r.rect, 3.0, edge, egui::StrokeKind::Middle);
+                }
+                DropZone::None => {}
+            }
+            if let Some(dragged) = r.dnd_release_payload::<String>() {
+                self.drop_node(dragged.as_str(), &target, zone);
+            }
+        }
+        if open && !children.is_empty() {
+            ui.indent(id_str, |ui| {
+                for child in children {
+                    self.show_node(ui, &child);
+                }
+            });
+        }
+    }
+}
diff --git a/pite-editor/src/app/viewport.rs b/pite-editor/src/app/viewport.rs
new file mode 100644
index 0000000..755898c
--- /dev/null
+++ b/pite-editor/src/app/viewport.rs
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+use std::time::Instant;
+
+use eframe::egui;
+use pite_core::PropValue;
+use pite_render::{OffscreenRenderer, Renderer2D};
+use pite_runtime::GameSession;
+
+use super::EditorApp;
+
+/// egui keys forwarded to the running scene, with the `pite.held` /
+/// `pite.pressed` names scripts use. Level-read each frame while playing.
+const GAME_KEYS: &[(egui::Key, &str)] = &[
+    (egui::Key::Space, "Space"),
+    (egui::Key::Enter, "Enter"),
+    (egui::Key::Escape, "Escape"),
+    (egui::Key::Tab, "Tab"),
+    (egui::Key::Backspace, "Backspace"),
+    (egui::Key::ArrowLeft, "ArrowLeft"),
+    (egui::Key::ArrowRight, "ArrowRight"),
+    (egui::Key::ArrowUp, "ArrowUp"),
+    (egui::Key::ArrowDown, "ArrowDown"),
+    (egui::Key::A, "A"),
+    (egui::Key::B, "B"),
+    (egui::Key::C, "C"),
+    (egui::Key::D, "D"),
+    (egui::Key::E, "E"),
+    (egui::Key::F, "F"),
+    (egui::Key::G, "G"),
+    (egui::Key::H, "H"),
+    (egui::Key::I, "I"),
+    (egui::Key::J, "J"),
+    (egui::Key::K, "K"),
+    (egui::Key::L, "L"),
+    (egui::Key::M, "M"),
+    (egui::Key::N, "N"),
+    (egui::Key::O, "O"),
+    (egui::Key::P, "P"),
+    (egui::Key::Q, "Q"),
+    (egui::Key::R, "R"),
+    (egui::Key::S, "S"),
+    (egui::Key::T, "T"),
+    (egui::Key::U, "U"),
+    (egui::Key::V, "V"),
+    (egui::Key::W, "W"),
+    (egui::Key::X, "X"),
+    (egui::Key::Y, "Y"),
+    (egui::Key::Z, "Z"),
+    (egui::Key::Num0, "0"),
+    (egui::Key::Num1, "1"),
+    (egui::Key::Num2, "2"),
+    (egui::Key::Num3, "3"),
+    (egui::Key::Num4, "4"),
+    (egui::Key::Num5, "5"),
+    (egui::Key::Num6, "6"),
+    (egui::Key::Num7, "7"),
+    (egui::Key::Num8, "8"),
+    (egui::Key::Num9, "9"),
+];
+
+/// Cursor in offscreen pixels from an egui pointer position. The texture
+/// stretches uniformly into its rect, so this is a pure rescale.
+pub(crate) fn viewport_cursor(
+    rect: egui::Rect,
+    view: (u32, u32),
+    pointer: egui::Pos2,
+) -> Option<(f64, f64)> {
+    if view.0 == 0 || view.1 == 0 || rect.width() <= 0.0 || rect.height() <= 0.0 {
+        return None;
+    }
+    let x = (pointer.x - rect.min.x) as f64 / rect.width() as f64 * view.0 as f64;
+    let y = (pointer.y - rect.min.y) as f64 / rect.height() as f64 * view.1 as f64;
+    Some((x, y))
+}
+
+/// Largest (width, height) with `view`'s aspect that fits inside `avail`.
+/// "Contain", not "fill": whichever axis binds first decides the scale, so
+/// the viewport grows and shrinks on both axes instead of blowing past the
+/// panel on the height axis when the editor is wide.
+pub(crate) fn fit_view(avail: egui::Vec2, view: (u32, u32)) -> egui::Vec2 {
+    let aspect = (view.0 as f32 / view.1.max(1) as f32).max(0.0001);
+    let avail = egui::Vec2::new(avail.x.max(1.0), avail.y.max(1.0));
+    if avail.x / avail.y > aspect {
+        egui::Vec2::new(avail.y * aspect, avail.y)
+    } else {
+        egui::Vec2::new(avail.x, avail.x / aspect)
+    }
+}
+
+impl EditorApp {
+    pub(super) fn toggle_play(&mut self) {
+        self.playing = !self.playing;
+        self.last_frame = Instant::now();
+        pite_script::input_clear();
+    }
+
+    /// Forward viewport input to the running scene's script input state.
+    /// Reads level state (`key_down`) and lets `input_set_key` derive edges;
+    /// runs before `session.frame()` so scripts consume this frame's state.
+    pub(super) fn pump_game_input(&mut self, ctx: &egui::Context) {
+        let (view_w, view_h) = self.view_size;
+        self.session.set_viewport(view_w, view_h);
+        if !(self.playing && self.viewport_hovered) {
+            return;
+        }
+        let rect = self.viewport_rect;
+        ctx.input(|i| {
+            for (key, name) in GAME_KEYS {
+                pite_script::input_set_key(name, i.key_down(*key));
+            }
+            pite_script::input_set_key("Shift", i.modifiers.shift);
+            pite_script::input_set_key("Control", i.modifiers.ctrl);
+            pite_script::input_set_key("Alt", i.modifiers.alt);
+            if let (Some(rect), Some(pos)) = (rect, i.pointer.hover_pos()) {
+                if let Some((x, y)) = viewport_cursor(rect, (view_w, view_h), pos) {
+                    pite_script::input_set_mouse(x, y);
+                }
+            }
+            pite_script::input_set_key(
+                "MouseLeft",
+                i.pointer.button_down(egui::PointerButton::Primary),
+            );
+            pite_script::input_set_key(
+                "MouseRight",
+                i.pointer.button_down(egui::PointerButton::Secondary),
+            );
+            pite_script::input_set_key(
+                "MouseMiddle",
+                i.pointer.button_down(egui::PointerButton::Middle),
+            );
+        });
+    }
+
+    pub(super) fn stop(&mut self) {
+        pite_script::input_clear();
+        match GameSession::open(&self.scene_path, false) {
+            Ok(session) => {
+                self.session = session;
+                self.playing = false;
+                self.viewport_dirty = true;
+                self.log("stopped, scene reset.");
+            }
+            Err(e) => self.log(format!("stop failed: {e:#}")),
+        }
+    }
+
+    pub(super) fn show_viewport(&mut self, ui: &mut egui::Ui) {
+        let (view_w, view_h) = self.view_size;
+        let want_refresh = self.playing || self.viewport_dirty;
+        if self.viewport.is_none() && !self.viewport_failed {
+            match OffscreenRenderer::new_offscreen(view_w, view_h) {
+                Ok(r) => {
+                    self.viewport = Some(r);
+                }
+                Err(e) => {
+                    self.viewport_failed = true;
+                    self.console
+                        .push(format!("viewport GPU unavailable, using fallback: {e:#}"));
+                }
+            }
+        }
+        let mut fresh_rgba: Option<Vec<u8>> = None;
+        let mut render_err: Option<String> = None;
+        if let Some(renderer) = self.viewport.as_mut() {
+            if want_refresh {
+                // The offscreen buffer is the design size: sync the session
+                // viewport here, not only while playing, or a fresh or just-
+                // stopped session still carries the (800, 600) init and the
+                // preview draws shrunken.
+                self.session.set_viewport(view_w, view_h);
+                let draw = renderer.begin_frame().and_then(|()| {
+                    self.session.draw_into(renderer)?;
+                    renderer.render_to_rgba()
+                });
+                match draw {
+                    Ok(rgba) => fresh_rgba = Some(rgba),
+                    Err(e) => render_err = Some(format!("viewport render failed: {e:#}")),
+                }
+            }
+        }
+        if let Some(rgba) = fresh_rgba {
+            let image =
+                egui::ColorImage::from_rgba_unmultiplied([view_w as usize, view_h as usize], &rgba);
+            match self.viewport_tex.as_mut() {
+                Some(handle) => handle.set(image, egui::TextureOptions::NEAREST),
+                None => {
+                    let handle = ui.ctx().load_texture(
+                        "pite-viewport",
+                        image,
+                        egui::TextureOptions::NEAREST,
+                    );
+                    self.viewport_tex = Some(handle);
+                }
+            }
+            self.viewport_dirty = false;
+        }
+        if let Some(err) = render_err {
+            self.log(err);
+        }
+        let textured = self.viewport.is_some() && self.viewport_tex.is_some();
+        let avail = ui.available_size();
+        let fitted = fit_view(avail, (view_w, view_h));
+        // Center the fitted rect in the space we measured: allocate the full
+        // avail, then paint into a centered sub-rect, so the viewport reads as
+        // framed content instead of content pinned to the top-left corner.
+        let (outer, _outer_painter) = ui.allocate_painter(avail, egui::Sense::hover());
+        let view_rect = egui::Rect::from_center_size(outer.rect.center(), fitted);
+        let resp = ui.interact(view_rect, ui.id().with("viewport"), egui::Sense::hover());
+        let painter = ui.painter_at(view_rect);
+        self.viewport_hovered = resp.hovered();
+        self.viewport_rect = Some(view_rect);
+        if textured {
+            if let Some(handle) = self.viewport_tex.as_ref() {
+                egui::Image::from_texture(handle).paint_at(ui, view_rect);
+            }
+        } else {
+            let nodes: Vec<(String, String, (f64, f64), String, (f64, f64))> =
+                self.session.host().with_tree(|t| {
+                    t.iter()
+                        .map(|n| {
+                            let pos = match n.props.get("position") {
+                                Some(PropValue::Vec2(x, y)) => (*x, *y),
+                                _ => (0.0, 0.0),
+                            };
+                            let text = match n.props.get("text") {
+                                Some(PropValue::Str(s)) => s.clone(),
+                                _ => String::new(),
+                            };
+                            let size = match n.props.get("size") {
+                                Some(PropValue::Vec2(w, h)) => (*w, *h),
+                                _ => (0.0, 0.0),
+                            };
+                            (n.id.to_string(), n.type_name.clone(), pos, text, size)
+                        })
+                        .collect()
+                });
+            let center = view_rect.center();
+            painter.rect_filled(view_rect, 0.0, crate::theme::BG);
+            for (id, type_name, (x, y), text, (w, h)) in nodes {
+                let p = center + egui::Vec2::new(x as f32, y as f32);
+                let color = if type_name == "Sprite2D" {
+                    egui::Color32::from_rgb(111, 179, 167)
+                } else {
+                    egui::Color32::from_rgb(124, 155, 184)
+                };
+                painter.circle_filled(p, 6.0, color);
+                if type_name == "Button" && w > 0.0 && h > 0.0 {
+                    painter.rect_stroke(
+                        egui::Rect::from_center_size(p, egui::Vec2::new(w as f32, h as f32)),
+                        4.0,
+                        egui::Stroke::new(1.0_f32, egui::Color32::from_rgb(111, 179, 167)),
+                        egui::StrokeKind::Middle,
+                    );
+                }
+                let caption = if text.is_empty() { id } else { text };
+                painter.text(
+                    p + egui::Vec2::new(10.0, -10.0),
+                    egui::Align2::LEFT_TOP,
+                    caption,
+                    egui::FontId::monospace(11.0),
+                    egui::Color32::from_rgb(201, 209, 216),
+                );
+            }
+        }
+    }
+}