feat(bootstrap): implement non-destructive mod overlay manager

crates/molotov-bootstrap/src/lib.rs

@@ -3,3 +3,4 @@ pub mod apk;
 pub mod cdn;
 pub mod error;
 pub mod fflags;
+pub mod mods;

crates/molotov-bootstrap/src/mods.rs

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+use crate::error::MolotovError;
+use std::collections::HashMap;
+use std::path::PathBuf;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum ModType {
+    DeathSound,
+    Cursor,
+    Font,
+}
+
+pub struct ModManager {
+    mods_root: PathBuf,
+    active_overlays: HashMap<String, PathBuf>,
+}
+
+impl ModManager {
+    pub fn new(mods_root: PathBuf) -> Self {
+        Self {
+            mods_root,
+            active_overlays: HashMap::new(),
+        }
+    }
+
+    pub fn scan_installed_mods(&mut self) -> Result<(), MolotovError> {
+        if !self.mods_root.exists() {
+            std::fs::create_dir_all(&self.mods_root)?;
+            return Ok(());
+        }
+
+        // Custom death sound check
+        let death_sound = self.mods_root.join("ouch.ogg");
+        if death_sound.exists() {
+            self.active_overlays
+                .insert("content/sounds/ouch.ogg".to_string(), death_sound);
+        }
+
+        // Custom cursor check
+        let cursor = self.mods_root.join("ArrowCursor.png");
+        if cursor.exists() {
+            self.active_overlays.insert(
+                "content/textures/Cursors/KeyboardMouse/ArrowCursor.png".to_string(),
+                cursor,
+            );
+        }
+
+        // Custom font check
+        let font = self.mods_root.join("custom_font.ttf");
+        if font.exists() {
+            self.active_overlays
+                .insert("content/fonts/arial.ttf".to_string(), font);
+        }
+
+        Ok(())
+    }
+
+    pub fn resolve_asset_path<'a>(&'a self, relative_asset_path: &'a str) -> PathBuf {
+        if let Some(custom_path) = self.active_overlays.get(relative_asset_path) {
+            custom_path.clone()
+        } else {
+            PathBuf::from(relative_asset_path)
+        }
+    }
+}

crates/molotov-bootstrap/tests/mods_test.rs

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+use molotov_bootstrap::mods::ModManager;
+use tempfile::tempdir;
+
+#[test]
+fn test_mod_redirection_for_custom_death_sound() {
+    let temp = tempdir().unwrap();
+    let mod_dir = temp.path().join("mods");
+    std::fs::create_dir_all(&mod_dir).unwrap();
+
+    let custom_sound = mod_dir.join("ouch.ogg");
+    std::fs::write(&custom_sound, b"OGG_CUSTOM_DATA").unwrap();
+
+    let mut manager = ModManager::new(mod_dir);
+    manager.scan_installed_mods().unwrap();
+
+    let default_asset = "content/sounds/ouch.ogg";
+    let resolved = manager.resolve_asset_path(default_asset);
+
+    assert_eq!(resolved, custom_sound, "Death sound must be redirected to user mod");
+}
+
+#[test]
+fn test_unmodded_asset_passes_through() {
+    let temp = tempdir().unwrap();
+    let manager = ModManager::new(temp.path().to_path_buf());
+    let default_asset = "content/textures/unmodified_texture.png";
+    let resolved = manager.resolve_asset_path(default_asset);
+
+    assert_eq!(resolved.to_str().unwrap(), default_asset);
+}