feat(runtime): game crash error UI, Wave 19 stability

- Game errors now show ErrorScene with the error message instead of silent pop
- ErrorScene now takes user back to Home (PopToRoot) on Enter
- Added Lua timeout documentation (blocked by Luau thread-safety — IPC sandbox needed)

Author: millsydotdev

crates/vibege-scene/src/scenes/error_scene.rs

@@ -26,23 +26,17 @@ impl Scene for ErrorScene {
         SceneKind::Modal
     }
 
-    fn on_create(&mut self, ctx: &mut SceneContext) -> SceneResult {
-        info!(msg = %self.message, "ErrorScene: displayed");
-        ctx.renderer.set_clear(0.15, 0.05, 0.05, 1.0);
-        Ok(SceneAction::Continue)
-    }
-
     fn on_render(&mut self, ctx: &mut SceneContext) -> SceneResult {
         ctx.renderer
             .draw_rect(200.0, 180.0, 400.0, 240.0, 0.2, 0.05, 0.05, 1.0);
         ctx.renderer
             .draw_rect(200.0, 180.0, 400.0, 40.0, 0.5, 0.1, 0.1, 1.0);
         ctx.renderer
-            .draw_text(220.0, 190.0, "Scene Error", 14.0, 1.0, 1.0, 1.0);
+            .draw_text(220.0, 190.0, "Game Error", 14.0, 1.0, 1.0, 1.0);
         ctx.renderer.draw_text(
             220.0,
             240.0,
-            "Something went wrong in this scene.",
+            "Something went wrong in this game.",
             9.0,
             0.8,
             0.8,
@@ -55,10 +49,18 @@ impl Scene for ErrorScene {
         Ok(SceneAction::Continue)
     }
 
+    fn on_create(&mut self, ctx: &mut SceneContext) -> SceneResult {
+        info!(msg = %self.message, "ErrorScene: displayed");
+        ctx.renderer.set_clear(0.15, 0.05, 0.05, 1.0);
+        Ok(SceneAction::Continue)
+    }
+
     fn on_update(&mut self, ctx: &mut SceneContext, _dt: f64) -> SceneResult {
         let inp = crate::input_helper::InputState::new(&ctx.input, &["enter"]);
         if inp.pressed(0) {
-            return Ok(SceneAction::PopModal);
+            return Ok(SceneAction::PopToRoot(Box::new(
+                super::home_scene::HomeScene::new(),
+            )));
         }
         Ok(SceneAction::Continue)
     }

crates/vibege-scene/src/scenes/game_manager.rs

@@ -1,5 +1,6 @@
 use std::sync::Arc;
 use std::sync::Mutex;
+use std::time::Duration;
 
 use mlua::{Function, Lua};
 use tracing::{info, warn};
@@ -10,6 +11,8 @@ use vibege_input::InputManager;
 use vibege_renderer::Renderer;
 use vibege_sdk::SdkState;
 
+const LUA_TIMEOUT: Duration = Duration::from_millis(1000);
+
 /// A live game session with its own isolated Lua VM.
 pub struct GameSession {
     lua: Lua,
@@ -94,6 +97,10 @@ impl GameSession {
         })
     }
 
+    /// Execute the game's update function.
+    /// NOTE: Lua is not `Send`, so we cannot use thread-based timeouts.
+    /// A long-running Lua script (infinite loop) will block the engine.
+    /// This will be resolved when games run in sandboxed processes (Wave 21).
     pub fn update(&self, dt: f64) -> Result<(), String> {
         SdkState::tick(&self.sdk_state, dt);
         if self.has_update {
@@ -106,6 +113,8 @@ impl GameSession {
         Ok(())
     }
 
+    /// Execute the game's render function.
+    /// NOTE: Same threading limitation as update().
     pub fn render(&self) -> Result<(), String> {
         if self.has_render {
             if let Ok(render_fn) = self.lua.globals().get::<Function>("render") {

crates/vibege-scene/src/scenes/game_scene.rs

@@ -1,5 +1,6 @@
 use std::sync::{Arc, Mutex};
 
+use super::error_scene::ErrorScene;
 use super::game_manager::GameSession;
 use crate::scene::{Scene, SceneAction, SceneContext, SceneId, SceneResult};
 use tracing::info;
@@ -106,7 +107,9 @@ impl Scene for GameScene {
             Ok(()) => Ok(SceneAction::Continue),
             Err(e) => {
                 info!(game = %self.game_name, "Game exited: {e}");
-                Ok(SceneAction::Pop)
+                Ok(SceneAction::PushModal(Box::new(ErrorScene::new(
+                    &format!("{} exited: {}", self.game_name, e),
+                ))))
             }
         }
     }
@@ -119,7 +122,9 @@ impl Scene for GameScene {
             Ok(()) => Ok(SceneAction::Continue),
             Err(e) => {
                 info!(game = %self.game_name, "Game render exited: {e}");
-                Ok(SceneAction::Pop)
+                Ok(SceneAction::PushModal(Box::new(ErrorScene::new(
+                    &format!("{} render error: {}", self.game_name, e),
+                ))))
             }
         }
     }