Add per-game overlay toggles (gamemode, mangohud, gamescope)

Games live under each Launcher as a Vec<Game>; the launcher itself
never picks up overlays, only games launched through `play` do.

- config: Game struct with gamemode/mangohud/gamescope fields, plus
  add_game / remove_game / set_game_flags methods.
- launcher::play_game wraps the game command as
  `gamescope [args] -- gamemoderun umu-run <exe>` (each layer optional)
  and sets MANGOHUD=1 when enabled.
- CLI: `play`, `games`, `config add-game`, `config remove-game`,
  `config set-game-flags`.
- tray: per-game submenus with Play + checkmark toggles for GameMode /
  MangoHud / Gamescope; toggles persist to disk immediately.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/config.rs

@@ -24,6 +24,10 @@ pub struct Launcher {
     /// Config::proton_version).
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub proton_version: Option<String>,
+    /// Games installed through this launcher. Overlays (gamemode, mangohud,
+    /// gamescope) only apply to games — the launcher itself always runs bare.
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub games: Vec<Game>,
 }
 
 impl Launcher {
@@ -31,6 +35,40 @@ impl Launcher {
     pub fn full_exe_path(&self) -> PathBuf {
         self.prefix_dir.join("drive_c").join(&self.exe_path)
     }
+
+    pub fn find_game(&self, name: &str) -> Option<&Game> {
+        self.games.iter().find(|g| g.name == name)
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Game {
+    /// Short CLI name (e.g. "overwatch").
+    pub name: String,
+    /// Display name for tray / menus.
+    pub display: String,
+    /// Path to the game exe relative to the launcher's prefix `drive_c/`.
+    pub exe_path: PathBuf,
+    /// Optional extra args passed to the game exe after umu-run.
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub args: Vec<String>,
+    /// Wrap the game in `gamemoderun`.
+    #[serde(default)]
+    pub gamemode: bool,
+    /// Set `MANGOHUD=1` for the game process.
+    #[serde(default)]
+    pub mangohud: bool,
+    /// Wrap the game in `gamescope`. `None` = disabled; `Some(vec)` = enabled
+    /// with those CLI args (empty vec = gamescope defaults).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub gamescope: Option<Vec<String>>,
+}
+
+impl Game {
+    /// Absolute path to the game exe inside the launcher's prefix.
+    pub fn full_exe_path(&self, launcher: &Launcher) -> PathBuf {
+        launcher.prefix_dir.join("drive_c").join(&self.exe_path)
+    }
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -93,6 +131,7 @@ pub fn presets() -> Vec<Launcher> {
             process_pattern: r"Battle\.net".into(),
             installer_url: None,
             proton_version: None,
+            games: vec![],
         },
         Launcher {
             name: "eaapp".into(),
@@ -105,6 +144,7 @@ pub fn presets() -> Vec<Launcher> {
             process_pattern: r"EADesktop\.exe".into(),
             installer_url: None,
             proton_version: None,
+            games: vec![],
         },
         Launcher {
             name: "epic".into(),
@@ -117,6 +157,7 @@ pub fn presets() -> Vec<Launcher> {
             process_pattern: r"EpicGamesLauncher\.exe".into(),
             installer_url: None,
             proton_version: None,
+            games: vec![],
         },
         Launcher {
             name: "ubisoft".into(),
@@ -129,6 +170,7 @@ pub fn presets() -> Vec<Launcher> {
             process_pattern: r"UbisoftConnect\.exe|upc\.exe".into(),
             installer_url: None,
             proton_version: None,
+            games: vec![],
         },
         Launcher {
             name: "gog".into(),
@@ -141,6 +183,7 @@ pub fn presets() -> Vec<Launcher> {
             process_pattern: r"GalaxyClient\.exe".into(),
             installer_url: None,
             proton_version: None,
+            games: vec![],
         },
         Launcher {
             name: "rockstar".into(),
@@ -153,6 +196,7 @@ pub fn presets() -> Vec<Launcher> {
             process_pattern: r"Rockstar Games.*Launcher\.exe".into(),
             installer_url: None,
             proton_version: None,
+            games: vec![],
         },
     ]
 }
@@ -280,12 +324,120 @@ impl Config {
             process_pattern,
             installer_url,
             proton_version: None,
+            games: vec![],
         });
         self.save()?;
         println!("\x1b[1;32m✓\x1b[0m Added launcher '{name}'.");
         Ok(())
     }
 
+    #[allow(clippy::too_many_arguments)]
+    pub fn add_game(
+        &mut self,
+        launcher: &str,
+        name: String,
+        display: Option<String>,
+        exe_path: PathBuf,
+        gamemode: bool,
+        mangohud: bool,
+        gamescope: Option<Vec<String>>,
+    ) -> Result<()> {
+        let l = self
+            .launchers
+            .iter_mut()
+            .find(|l| l.name == launcher)
+            .ok_or_else(|| {
+                anyhow::anyhow!("no launcher named '{launcher}'")
+            })?;
+        if l.games.iter().any(|g| g.name == name) {
+            anyhow::bail!(
+                "launcher '{launcher}' already has a game named '{name}'"
+            );
+        }
+        let display = display.unwrap_or_else(|| name.clone());
+        l.games.push(Game {
+            name: name.clone(),
+            display,
+            exe_path,
+            args: vec![],
+            gamemode,
+            mangohud,
+            gamescope,
+        });
+        self.save()?;
+        println!(
+            "\x1b[1;32m✓\x1b[0m Added game '{name}' under launcher '{launcher}'."
+        );
+        Ok(())
+    }
+
+    pub fn remove_game(&mut self, launcher: &str, name: &str) -> Result<()> {
+        let l = self
+            .launchers
+            .iter_mut()
+            .find(|l| l.name == launcher)
+            .ok_or_else(|| {
+                anyhow::anyhow!("no launcher named '{launcher}'")
+            })?;
+        let before = l.games.len();
+        l.games.retain(|g| g.name != name);
+        if l.games.len() == before {
+            anyhow::bail!(
+                "launcher '{launcher}' has no game named '{name}'"
+            );
+        }
+        self.save()?;
+        println!("\x1b[1;32m✓\x1b[0m Removed game '{name}' from '{launcher}'.");
+        Ok(())
+    }
+
+    /// Update per-game overlay flags. Each arg is `None` = leave as-is.
+    /// `gamescope = Some(None)` disables it; `Some(Some(vec))` enables with args.
+    pub fn set_game_flags(
+        &mut self,
+        launcher: &str,
+        name: &str,
+        gamemode: Option<bool>,
+        mangohud: Option<bool>,
+        gamescope: Option<Option<Vec<String>>>,
+    ) -> Result<()> {
+        if gamemode.is_none() && mangohud.is_none() && gamescope.is_none() {
+            anyhow::bail!(
+                "nothing to set — pass --gamemode, --mangohud, --gamescope, or --no-gamescope"
+            );
+        }
+        let l = self
+            .launchers
+            .iter_mut()
+            .find(|l| l.name == launcher)
+            .ok_or_else(|| {
+                anyhow::anyhow!("no launcher named '{launcher}'")
+            })?;
+        let g = l
+            .games
+            .iter_mut()
+            .find(|g| g.name == name)
+            .ok_or_else(|| {
+                anyhow::anyhow!(
+                    "launcher '{launcher}' has no game named '{name}'"
+                )
+            })?;
+        if let Some(v) = gamemode {
+            g.gamemode = v;
+        }
+        if let Some(v) = mangohud {
+            g.mangohud = v;
+        }
+        if let Some(v) = gamescope {
+            g.gamescope = v;
+        }
+        self.save()?;
+        println!(
+            "\x1b[1;32m✓\x1b[0m Updated flags for '{launcher}/{name}'."
+        );
+        Ok(())
+    }
+
     pub fn remove_launcher(&mut self, name: &str) -> Result<()> {
         let before = self.launchers.len();
         self.launchers.retain(|l| l.name != name);