Asset database file ops + script-file creation helpers

Groundwork for the Stage-10 editor-UX batch (file explorer, New Script
button), all pure logic proven by unit tests:

- `AssetDatabase::move_asset` / `move_folder` / `delete_asset`: perform
  the disk operation and the uid-map update together, so renaming or
  moving an asset (or a whole folder) keeps its uid and every saved
  `AssetRef` resolving. Kinds re-classify from the new path; `..` and
  existing destinations are refused via the new `AssetDbError` enum;
  deleted uids are never reused.
- Editor `assets.rs`: `script_template` (compiles under the sandboxed
  ScriptEngine — covered by a test), `sanitize_script_stem`, and
  `create_script_file` which writes a collision-free
  `assets/scripts/<stem>.rhai` and returns the relative path for
  database registration.
- docs/assets.md: new "File operations" section + the missing Script
  row in the typed-folder table.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/assets.md

@@ -164,10 +164,34 @@ breaking references, since the uid travels with the file in the manifest.
 | `Model` | `models/` | `gltf`, `glb`, `obj` |
 | `Audio` | `audio/` | `wav`, `ogg`, `mp3`, `flac` |
 | `Ui` | `ui/` | (recognised by folder — shares `.ron` with scenes) |
+| `Script` | `scripts/` | `rhai` |
 
 `AssetKind::classify(path)` infers the kind: the leading folder wins, with the
 file extension as a fallback for files dropped directly in `assets/`.
 
+### File operations — rename, move, delete
+
+The database also *performs* file reorganisation, so the editor's file explorer
+(and any tool) can rename or move assets **without breaking saved references**
+— the disk operation and the uid map are updated together:
+
+```rust
+# use oxide_engine::asset::{AssetDatabase, AssetUid};
+# fn demo(db: &mut AssetDatabase, uid: AssetUid) -> Result<(), oxide_engine::asset::AssetDbError> {
+db.move_asset(uid, "textures/env/brick.png")?; // rename/move; uid unchanged
+db.move_folder("textures/env", "textures/world")?; // every entry under it follows
+db.delete_asset(uid)?;                         // file + entry; uid never reused
+db.save()?;                                    // persist the new paths
+# Ok(())
+# }
+```
+
+All three refuse to touch anything outside `assets/` (`..` is rejected) and
+refuse to overwrite an existing destination ([`AssetDbError`] has a variant per
+failure). Kinds are re-classified from the new path, since a move can change
+the typed folder. Deleting drops the entry but never reuses its uid — a
+dangling reference stays dangling instead of silently pointing at a new file.
+
 ### Asset-reference fields in the inspector
 
 A component points at an asset with an [`AssetRef<T>`] field — **not** a live
@@ -209,6 +233,7 @@ projects are seeded with a bundled default UI font (Inter, SIL OFL) under
 `fonts/`, referenced by its project-relative path like any other asset.
 
 [`AssetDatabase`]: ../engine/src/asset/database.rs
+[`AssetDbError`]: ../engine/src/asset/database.rs
 [`AssetKind`]: ../engine/src/asset/database.rs
 [`AssetUid`]: ../engine/src/asset/database.rs
 [`AssetRef<T>`]: ../engine/src/asset/database.rs

editor/src/assets.rs

@@ -1,5 +1,7 @@
-//! Bundled editor assets — locating the shared `assets/` tree and seeding a
-//! new project's default content (currently the default UI font).
+//! Bundled editor assets — locating the shared `assets/` tree, seeding a new
+//! project's default content (currently the default UI font), and creating new
+//! script files from the built-in template (the inspector's "New Script"
+//! button).
 //!
 //! The editor ships a small set of shared assets (icons, the default UI font, …)
 //! installed by `install.sh` to `$PREFIX/share/oxide/assets`. At runtime we have
@@ -91,6 +93,79 @@ pub fn seed_default_font(project_assets_dir: &Path) -> std::io::Result<bool> {
     Ok(true)
 }
 
+/// The `.rhai` source the "New Script" button writes, personalised with the
+/// script's file stem so the Console output identifies which script speaks.
+///
+/// Kept to the two lifecycle hooks `docs/scripting.md` teaches first; the
+/// `update` body ships commented out so a freshly created script visibly runs
+/// (the `init` print) without moving anything until the author opts in.
+pub fn script_template(stem: &str) -> String {
+    format!(
+        r#"// {stem}.rhai — attached via a Script component.
+//
+// Top-level statements run once when the script (re)starts. `init()` runs
+// once after them; `update(dt)` runs every frame (dt = seconds).
+
+fn init() {{
+    print("{stem}: init");
+}}
+
+fn update(dt) {{
+    // e.g. rotate_y(dt * 1.5);
+}}
+"#
+    )
+}
+
+/// Reduces a typed script name to a safe file stem: keeps ASCII alphanumerics,
+/// `-` and `_`, folds anything else (spaces, punctuation, Unicode) to `_`,
+/// collapses runs, trims the ends, and drops a trailing `.rhai` the user may
+/// have typed. An unusable input yields `"new_script"`.
+pub fn sanitize_script_stem(name: &str) -> String {
+    let trimmed = name.trim();
+    let trimmed = trimmed.strip_suffix(".rhai").unwrap_or(trimmed);
+    let mut stem = String::with_capacity(trimmed.len());
+    for c in trimmed.chars() {
+        if c.is_ascii_alphanumeric() || c == '-' || c == '_' {
+            stem.push(c);
+        } else if !stem.ends_with('_') {
+            stem.push('_');
+        }
+    }
+    let stem = stem.trim_matches('_');
+    if stem.is_empty() {
+        "new_script".to_owned()
+    } else {
+        stem.to_owned()
+    }
+}
+
+/// Creates a new script file under `<assets_dir>/scripts/` from the template,
+/// returning its assets-relative path (e.g. `"scripts/my_script.rhai"`) for
+/// registration in the [`AssetDatabase`](oxide_engine::asset::AssetDatabase).
+///
+/// The desired name is [sanitized](sanitize_script_stem); a taken name gets a
+/// numeric suffix (`stem_2`, `stem_3`, …) instead of failing or overwriting,
+/// so the button always succeeds on a writable project.
+pub fn create_script_file(assets_dir: &Path, desired_name: &str) -> std::io::Result<String> {
+    use oxide_engine::asset::AssetKind;
+
+    let stem = sanitize_script_stem(desired_name);
+    let dir = assets_dir.join(AssetKind::Script.folder());
+    std::fs::create_dir_all(&dir)?;
+    let mut candidate = stem.clone();
+    let mut n = 1;
+    while dir.join(format!("{candidate}.rhai")).exists() {
+        n += 1;
+        candidate = format!("{stem}_{n}");
+    }
+    std::fs::write(
+        dir.join(format!("{candidate}.rhai")),
+        script_template(&candidate),
+    )?;
+    Ok(format!("{}/{candidate}.rhai", AssetKind::Script.folder()))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -124,4 +199,50 @@ mod tests {
 
         std::fs::remove_dir_all(tmp).ok();
     }
+
+    #[test]
+    fn sanitize_covers_typed_names() {
+        assert_eq!(sanitize_script_stem("spin"), "spin");
+        assert_eq!(sanitize_script_stem("  My Cool Script! "), "My_Cool_Script");
+        assert_eq!(sanitize_script_stem("door.rhai"), "door");
+        assert_eq!(sanitize_script_stem("a//b\\c"), "a_b_c");
+        assert_eq!(sanitize_script_stem("čárka"), "rka");
+        // Unusable inputs fall back rather than producing "" or "_".
+        assert_eq!(sanitize_script_stem(""), "new_script");
+        assert_eq!(sanitize_script_stem("!!!"), "new_script");
+        assert_eq!(sanitize_script_stem(".rhai"), "new_script");
+    }
+
+    #[test]
+    fn create_script_writes_template_and_dodges_collisions() {
+        let mut tmp = std::env::temp_dir();
+        tmp.push(format!("oxide_newscript_{}", std::process::id()));
+        let assets = tmp.join("assets");
+        std::fs::create_dir_all(&assets).unwrap();
+
+        let rel = create_script_file(&assets, "door opener").unwrap();
+        assert_eq!(rel, "scripts/door_opener.rhai");
+        let text = std::fs::read_to_string(assets.join(&rel)).unwrap();
+        assert!(text.contains("fn update(dt)"));
+
+        // Same name again: suffixed, nothing overwritten.
+        let rel2 = create_script_file(&assets, "door opener").unwrap();
+        assert_eq!(rel2, "scripts/door_opener_2.rhai");
+        let rel3 = create_script_file(&assets, "door opener").unwrap();
+        assert_eq!(rel3, "scripts/door_opener_3.rhai");
+
+        std::fs::remove_dir_all(tmp).ok();
+    }
+
+    #[test]
+    fn template_compiles_in_the_script_engine() {
+        // The template must never ship a syntax error: compile it exactly as
+        // the runtime would.
+        let asset = oxide_script::ScriptAsset::from_source(
+            "new_script.rhai",
+            script_template("new_script"),
+        );
+        let engine = oxide_script::ScriptEngine::new();
+        engine.compile(&asset).expect("template compiles");
+    }
 }

editor/src/shell.rs

@@ -2251,7 +2251,7 @@ impl<'a> ShellTabViewer<'a> {
         stroke_rect(
             &painter,
             tab_rect.shrink(1.5),
-            egui::Stroke::new(3.0, color),
+            egui::Stroke::new(3.0_f32, color),
         );
         painter.text(
             tab_rect.left_top() + egui::vec2(8.0, 6.0),
@@ -2312,7 +2312,7 @@ impl<'a> ShellTabViewer<'a> {
                 egui::Color32::from_rgb(110, 220, 120) // green: solid
             };
             let selected = self.state.selected == Some(entity);
-            let stroke = egui::Stroke::new(if selected { 2.0 } else { 1.2 }, color);
+            let stroke = egui::Stroke::new(if selected { 2.0_f32 } else { 1.2_f32 }, color);
             for (a, b) in collider_wire_segments(&col) {
                 let (Some(pa), Some(pb)) = (
                     project(pose.transform_point(a), &overlay.view_proj, tab_rect),
@@ -2344,7 +2344,7 @@ impl<'a> ShellTabViewer<'a> {
             project(viz.origin, &overlay.view_proj, tab_rect),
             project(viz.end, &overlay.view_proj, tab_rect),
         ) {
-            painter.line_segment([a, b], egui::Stroke::new(1.5, cyan));
+            painter.line_segment([a, b], egui::Stroke::new(1.5_f32, cyan));
         }
 
         // The hit surface: a dot at the contact point + a normal whisker.
@@ -2359,7 +2359,7 @@ impl<'a> ShellTabViewer<'a> {
                 project(hit.point, &overlay.view_proj, tab_rect),
                 project(tip, &overlay.view_proj, tab_rect),
             ) {
-                painter.line_segment([a, b], egui::Stroke::new(2.0, magenta));
+                painter.line_segment([a, b], egui::Stroke::new(2.0_f32, magenta));
             }
         }
     }
@@ -2470,7 +2470,7 @@ impl<'a> ShellTabViewer<'a> {
         ) else {
             return;
         };
-        painter.line_segment([pa, pb], egui::Stroke::new(2.5, color));
+        painter.line_segment([pa, pb], egui::Stroke::new(2.5_f32, color));
         // Arrowhead at the tip — a small filled triangle perpendicular to
         // the line direction in screen space.
         let dir = (pb - pa).normalized();
@@ -2521,7 +2521,7 @@ impl<'a> ShellTabViewer<'a> {
         } else {
             egui::Color32::from_rgba_unmultiplied(255, 120, 120, if engaged { 220 } else { 130 })
         };
-        let stroke = egui::Stroke::new(1.5, color);
+        let stroke = egui::Stroke::new(1.5_f32, color);
         painter.add(egui::Shape::convex_polygon(projected, color, stroke));
     }
 
@@ -2551,7 +2551,7 @@ impl<'a> ShellTabViewer<'a> {
             return;
         }
         let color = axis_color(axis, engaged);
-        painter.add(egui::Shape::line(pts, egui::Stroke::new(2.0, color)));
+        painter.add(egui::Shape::line(pts, egui::Stroke::new(2.0_f32, color)));
     }
 
     fn hierarchy(&mut self, ui: &mut egui::Ui) {
@@ -2705,7 +2705,7 @@ impl<'a> ShellTabViewer<'a> {
                             DropZone::Child
                         };
                         let accent = ui.visuals().selection.bg_fill;
-                        let line = egui::Stroke::new(2.0, accent);
+                        let line = egui::Stroke::new(2.0_f32, accent);
                         match zone {
                             DropZone::Before => {
                                 ui.painter().line_segment(
@@ -3333,7 +3333,7 @@ impl<'a> ShellTabViewer<'a> {
                     if r.contains(pos) {
                         let above = (pos.y - r.top()) < r.height() / 2.0;
                         let accent = ui.visuals().selection.bg_fill;
-                        let line = egui::Stroke::new(2.0, accent);
+                        let line = egui::Stroke::new(2.0_f32, accent);
                         let y = if above { r.top() } else { r.bottom() };
                         ui.painter().line_segment(
                             [egui::pos2(r.left(), y), egui::pos2(r.right(), y)],
@@ -5165,7 +5165,7 @@ fn draw_ui_preview(ui: &mut egui::Ui, panel: &UiPanel) {
     stroke_rect(
         &painter,
         egui::Rect::from_min_size(origin, draw),
-        egui::Stroke::new(1.0, egui::Color32::DARK_GRAY),
+        egui::Stroke::new(1.0_f32, egui::Color32::DARK_GRAY),
     );
 
     let theme = UiTheme::new();

engine/src/asset/database.rs

@@ -178,6 +178,30 @@ pub fn asset_ref_target(type_name: &str) -> Option<&str> {
     Some(inner.rsplit("::").next().unwrap_or(inner).trim())
 }
 
+/// Errors from [`AssetDatabase`] file operations ([`move_asset`], [`delete_asset`],
+/// [`move_folder`]) — the ops that touch both the on-disk file *and* the uid map.
+///
+/// [`move_asset`]: AssetDatabase::move_asset
+/// [`delete_asset`]: AssetDatabase::delete_asset
+/// [`move_folder`]: AssetDatabase::move_folder
+#[derive(Debug, thiserror::Error)]
+pub enum AssetDbError {
+    /// The uid is not recorded in the database.
+    #[error("unknown asset uid {0:?}")]
+    UnknownUid(AssetUid),
+    /// The destination path is already taken, in the database or on disk.
+    /// Nothing was changed; pick another name.
+    #[error("destination already exists: {0}")]
+    DestinationExists(String),
+    /// The path is empty, escapes the assets directory (`..`), or would move a
+    /// folder into itself.
+    #[error("invalid assets-relative path: {0:?}")]
+    InvalidPath(String),
+    /// The underlying filesystem operation failed.
+    #[error(transparent)]
+    Io(#[from] std::io::Error),
+}
+
 /// A stable, per-project identifier for one asset.
 ///
 /// Unlike [`AssetId`](super::AssetId) — which is process-unique and changes
@@ -507,6 +531,126 @@ impl AssetDatabase {
         Some(server.load::<T>(path))
     }
 
+    // --- file operations (disk + uid map together) --------------------------
+    //
+    // These keep the uid attached to its asset across renames/moves — the whole
+    // point of the uid layer — so the editor's file explorer can reorganise a
+    // project without breaking any saved `AssetRef`. Deletion drops the entry
+    // but never reuses its uid (the allocator only counts up).
+
+    /// Renames/moves the asset `uid` to `new_relative_path` (relative to
+    /// `assets/`), on disk and in the map, **keeping its uid** so saved
+    /// references still resolve. The kind is re-classified from the new path.
+    /// Parent directories are created as needed; moving onto an existing path
+    /// is refused. A no-op if the path is unchanged.
+    ///
+    /// Call [`save`](Self::save) afterwards to persist the new path.
+    pub fn move_asset(
+        &mut self,
+        uid: AssetUid,
+        new_relative_path: impl AsRef<str>,
+    ) -> Result<(), AssetDbError> {
+        let entry = self.by_uid.get(&uid).ok_or(AssetDbError::UnknownUid(uid))?;
+        let new_path = checked_relative(new_relative_path.as_ref())?;
+        if new_path == entry.path {
+            return Ok(());
+        }
+        if self.by_path.contains_key(&new_path) {
+            return Err(AssetDbError::DestinationExists(new_path));
+        }
+        let assets_dir = self.assets_dir();
+        let from_abs = assets_dir.join(entry.path.replace('/', std::path::MAIN_SEPARATOR_STR));
+        let to_abs = assets_dir.join(new_path.replace('/', std::path::MAIN_SEPARATOR_STR));
+        if to_abs.exists() {
+            return Err(AssetDbError::DestinationExists(new_path));
+        }
+        if let Some(parent) = to_abs.parent() {
+            std::fs::create_dir_all(parent)?;
+        }
+        std::fs::rename(&from_abs, &to_abs)?;
+
+        let old_path = entry.path.clone();
+        self.by_path.remove(&old_path);
+        self.by_path.insert(new_path.clone(), uid);
+        let entry = self.by_uid.get_mut(&uid).expect("entry checked above");
+        entry.kind = AssetKind::classify(&new_path);
+        entry.path = new_path;
+        Ok(())
+    }
+
+    /// Deletes the asset `uid`: removes its file from disk and drops its entry.
+    /// A file already missing from disk is fine (the entry is still dropped);
+    /// the uid is never reused. Call [`save`](Self::save) afterwards.
+    pub fn delete_asset(&mut self, uid: AssetUid) -> Result<(), AssetDbError> {
+        let entry = self.by_uid.get(&uid).ok_or(AssetDbError::UnknownUid(uid))?;
+        let abs = self
+            .assets_dir()
+            .join(entry.path.replace('/', std::path::MAIN_SEPARATOR_STR));
+        match std::fs::remove_file(&abs) {
+            Ok(()) => {}
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
+            Err(e) => return Err(e.into()),
+        }
+        let path = entry.path.clone();
+        self.by_uid.remove(&uid);
+        self.by_path.remove(&path);
+        Ok(())
+    }
+
+    /// Renames/moves the folder `from` to `to` (both relative to `assets/`),
+    /// on disk and in the map: every entry under `from/` is rewritten to live
+    /// under `to/`, **keeping its uid** (kinds are re-classified — moving out
+    /// of a typed folder can change them). Refuses to overwrite an existing
+    /// destination or to move a folder into itself. Returns how many entries
+    /// moved. Call [`save`](Self::save) afterwards.
+    pub fn move_folder(
+        &mut self,
+        from: impl AsRef<str>,
+        to: impl AsRef<str>,
+    ) -> Result<usize, AssetDbError> {
+        let from = checked_relative(from.as_ref())?;
+        let to = checked_relative(to.as_ref())?;
+        if from == to {
+            return Ok(0);
+        }
+        if to.starts_with(&format!("{from}/")) {
+            return Err(AssetDbError::InvalidPath(to));
+        }
+        let assets_dir = self.assets_dir();
+        let from_abs = assets_dir.join(from.replace('/', std::path::MAIN_SEPARATOR_STR));
+        let to_abs = assets_dir.join(to.replace('/', std::path::MAIN_SEPARATOR_STR));
+        if !from_abs.is_dir() {
+            return Err(AssetDbError::Io(std::io::Error::new(
+                std::io::ErrorKind::NotFound,
+                format!("no such folder under assets/: {from}"),
+            )));
+        }
+        if to_abs.exists() {
+            return Err(AssetDbError::DestinationExists(to));
+        }
+        if let Some(parent) = to_abs.parent() {
+            std::fs::create_dir_all(parent)?;
+        }
+        std::fs::rename(&from_abs, &to_abs)?;
+
+        let prefix = format!("{from}/");
+        let moved: Vec<AssetUid> = self
+            .by_uid
+            .values()
+            .filter(|e| e.path.starts_with(&prefix))
+            .map(|e| e.uid)
+            .collect();
+        for &uid in &moved {
+            let entry = self.by_uid.get_mut(&uid).expect("collected above");
+            let new_path = format!("{to}/{}", &entry.path[prefix.len()..]);
+            let old_path = std::mem::replace(&mut entry.path, new_path.clone());
+            entry.kind = AssetKind::classify(&new_path);
+            self.by_path.remove(&old_path);
+            self.by_path.insert(new_path, uid);
+        }
+        Ok(moved.len())
+    }
+
     // --- internals ---------------------------------------------------------
 
     fn highest_uid(&self) -> u64 {
@@ -522,6 +666,20 @@ fn normalize_relative(path: &str) -> String {
     trimmed.trim_start_matches('/').to_string()
 }
 
+/// Normalizes like [`normalize_relative`] and rejects paths that are empty or
+/// escape the assets directory (`..` components) — file operations must never
+/// touch anything outside `assets/`.
+fn checked_relative(path: &str) -> Result<String, AssetDbError> {
+    let norm = normalize_relative(path);
+    let escapes = Path::new(&norm)
+        .components()
+        .any(|c| !matches!(c, std::path::Component::Normal(_)));
+    if norm.is_empty() || escapes {
+        return Err(AssetDbError::InvalidPath(path.to_string()));
+    }
+    Ok(norm)
+}
+
 /// Recursively collects files under `dir`, pushing each one's path relative to
 /// `base` (forward slashes) into `out`. A missing `dir` is silently skipped.
 fn collect_files(dir: &Path, base: &Path, out: &mut Vec<String>) {
@@ -738,6 +896,128 @@ mod tests {
         std::fs::remove_dir_all(root).ok();
     }
 
+    #[test]
+    fn move_asset_keeps_uid_and_reclassifies() {
+        let root = temp_root("move_asset");
+        touch_asset(&root, "textures/wall.png");
+        let mut db = AssetDatabase::new(&root);
+        db.scan();
+        let uid = db.uid_of("textures/wall.png").unwrap();
+
+        // Rename within the folder: same uid, file moved on disk.
+        db.move_asset(uid, "textures/brick.png").unwrap();
+        assert_eq!(db.relative_path(uid), Some("textures/brick.png"));
+        assert!(db.uid_of("textures/wall.png").is_none());
+        assert!(!root.join(ASSETS_DIR).join("textures/wall.png").exists());
+        assert!(root.join(ASSETS_DIR).join("textures/brick.png").exists());
+
+        // Move into a subfolder that does not exist yet (created), then out of
+        // the typed folder entirely — kind follows the path.
+        db.move_asset(uid, "textures/env/brick.png").unwrap();
+        assert!(root
+            .join(ASSETS_DIR)
+            .join("textures/env/brick.png")
+            .exists());
+        assert_eq!(db.entry(uid).unwrap().kind, AssetKind::Texture);
+        db.move_asset(uid, "misc/brick.dat").unwrap();
+        assert_eq!(db.entry(uid).unwrap().kind, AssetKind::Other);
+
+        // A rescan does not disturb the moved entry's uid... (misc/ is not a
+        // typed folder, so the entry survives only because scan never saw it —
+        // move back first to prove the typed-folder case.)
+        db.move_asset(uid, "textures/brick.png").unwrap();
+        db.scan();
+        assert_eq!(db.uid_of("textures/brick.png"), Some(uid));
+
+        // No-op and error cases.
+        db.move_asset(uid, "textures/brick.png").unwrap(); // unchanged path: Ok
+        touch_asset(&root, "textures/taken.png");
+        db.scan();
+        assert!(matches!(
+            db.move_asset(uid, "textures/taken.png"),
+            Err(AssetDbError::DestinationExists(_))
+        ));
+        assert!(matches!(
+            db.move_asset(uid, "../outside.png"),
+            Err(AssetDbError::InvalidPath(_))
+        ));
+        assert!(matches!(
+            db.move_asset(AssetUid(999), "textures/x.png"),
+            Err(AssetDbError::UnknownUid(_))
+        ));
+
+        std::fs::remove_dir_all(root).ok();
+    }
+
+    #[test]
+    fn delete_asset_removes_file_and_entry_without_reusing_uid() {
+        let root = temp_root("delete_asset");
+        touch_asset(&root, "audio/click.wav");
+        let mut db = AssetDatabase::new(&root);
+        db.scan();
+        let uid = db.uid_of("audio/click.wav").unwrap();
+
+        db.delete_asset(uid).unwrap();
+        assert!(db.entry(uid).is_none());
+        assert!(!root.join(ASSETS_DIR).join("audio/click.wav").exists());
+
+        // The freed uid is not handed to the next registration.
+        let next = db.register("audio/other.wav");
+        assert_ne!(next, uid);
+
+        // Deleting an entry whose file is already gone still drops the entry.
+        std::fs::remove_file(root.join(ASSETS_DIR).join("audio/other.wav")).ok();
+        db.delete_asset(next).unwrap();
+        assert!(db.entry(next).is_none());
+
+        assert!(matches!(
+            db.delete_asset(uid),
+            Err(AssetDbError::UnknownUid(_))
+        ));
+
+        std::fs::remove_dir_all(root).ok();
+    }
+
+    #[test]
+    fn move_folder_rewrites_entries_and_guards_self_moves() {
+        let root = temp_root("move_folder");
+        touch_asset(&root, "textures/env/wall.png");
+        touch_asset(&root, "textures/env/floor.png");
+        touch_asset(&root, "textures/hero.png");
+        let mut db = AssetDatabase::new(&root);
+        db.scan();
+        let wall = db.uid_of("textures/env/wall.png").unwrap();
+        let hero = db.uid_of("textures/hero.png").unwrap();
+
+        let moved = db.move_folder("textures/env", "textures/world").unwrap();
+        assert_eq!(moved, 2);
+        assert_eq!(db.relative_path(wall), Some("textures/world/wall.png"));
+        assert!(db.uid_of("textures/world/floor.png").is_some());
+        assert_eq!(db.relative_path(hero), Some("textures/hero.png"));
+        assert!(root
+            .join(ASSETS_DIR)
+            .join("textures/world/wall.png")
+            .exists());
+        assert!(!root.join(ASSETS_DIR).join("textures/env").exists());
+
+        // Guards: into itself, onto an existing folder, missing source.
+        assert!(matches!(
+            db.move_folder("textures", "textures/world/deeper"),
+            Err(AssetDbError::InvalidPath(_))
+        ));
+        std::fs::create_dir_all(root.join(ASSETS_DIR).join("models")).unwrap();
+        assert!(matches!(
+            db.move_folder("textures/world", "models"),
+            Err(AssetDbError::DestinationExists(_))
+        ));
+        assert!(matches!(
+            db.move_folder("textures/nope", "textures/x"),
+            Err(AssetDbError::Io(_))
+        ));
+
+        std::fs::remove_dir_all(root).ok();
+    }
+
     struct TxtLoader;
     impl crate::asset::AssetLoader for TxtLoader {
         type Asset = String;

engine/src/asset/mod.rs

@@ -18,7 +18,8 @@ mod handle;
 mod server;
 
 pub use database::{
-    asset_ref_target, AssetDatabase, AssetEntry, AssetKind, AssetRef, AssetUid, ASSET_MANIFEST_FILE,
+    asset_ref_target, AssetDatabase, AssetDbError, AssetEntry, AssetKind, AssetRef, AssetUid,
+    ASSET_MANIFEST_FILE,
 };
 pub use gltf::{load_gltf, load_gltf_slice, GltfError, GltfLoader, GltfMesh, GltfModel};
 pub use handle::{AssetId, Handle, LoadState};