Fix the reset button doing nothing or looping the start screen when pressed repeatedly (#719)

* Make the reset button reliable from any screen

Pressing reset repeatedly near app start could do nothing, fade the music
with no reset, or bounce the press-start screen back to itself. Three
defects in the old handler:

- It ran from the ImGui widget, racing the menu state machine; a press
  landing mid-fade was re-advanced by the in-flight transition (the
  press-start loop).
- It always wrote gGamestateNext = MAIN_MENU_FROM_QUIT; once the game was
  already in that state a repeat write is swallowed by the != guard in
  main.c, so nothing happened.
- CM_ResetAudio ran unconditionally, so the music faded even when the
  reset was swallowed.

The widget now only sets an atomic request flag; ApplyPendingReset (top of
push_frame, on the game loop) performs the reset. It alternates between
the two identical FROM_QUIT gamestates so every press trips the gamestate
switch, and re-enters the menus through the intro's own transition
protocol (FADE_MODE_LOGO -> setup_menus rebuild + fresh fade-in), which
replaces any in-flight transition. Audio only fades when a reset actually
executes. The dead gSkipIntro switch in the old handler (an unconditional
override below it always won) is gone; behavior is unchanged: reset lands
on the logo intro, or the start menu in debug mode.

Play-verified: hammering reset during the splash screens restarts the
logo every press; reset mid-fade after press-start no longer loops back;
resets from the main menu and mid-race work as before.

* Honor gSkipIntro when picking the post-reset screen

Review feedback on #719: restore the gSkipIntro switch from the old
handler instead of hard-coding the logo intro, keeping the debug-mode
override on top (no else), matching the boot-time logic in main().

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

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: MegaMech <MegaMech@users.noreply.github.com>

3 files changed, 72 insertions, 40 deletions

diff --git a/src/port/Game.cpp b/src/port/Game.cpp
index 8ccd382e6..1c6d49af9 100644
--- a/src/port/Game.cpp
+++ b/src/port/Game.cpp
@@ -6,6 +6,7 @@
 
 #include <fast/Fast3dWindow.h>
 #include <memory>
+#include <atomic>
 #include "engine/World.h"
 #include "engine/AllTracks.h"
 
@@ -911,7 +912,73 @@ void CM_ResetAudio(void) {
 }
 }
 
+static std::atomic<bool> sResetRequested{ false };
+
+void CM_RequestReset(void) {
+    sResetRequested.store(true);
+}
+
+// The reset widget only requests; the reset is applied here at the top of the
+// game frame. Applying it from the widget raced the menu state machine: a
+// press landing mid-fade was re-advanced by the in-flight transition, and a
+// repeat press rewrote the gamestate it had already set, which the != guard
+// in main.c swallows while the audio fade still runs (silent no-op).
+static void ApplyPendingReset() {
+    if (!sResetRequested.exchange(false)) {
+        return;
+    }
+
+    // The FROM_QUIT gamestates run identical inits; alternating keeps
+    // gGamestateNext != gGamestate true so every press re-enters the menus.
+    gGamestateNext = (gGamestate == MAIN_MENU_FROM_QUIT) ? START_MENU_FROM_QUIT : MAIN_MENU_FROM_QUIT;
+    gIsGamePaused = 0;
+    // Reset credits
+    D_800DC5E4 = 0;
+    gTourComplete = false;
+    SetMarioRaceway();
+    memset(&gGameModeMenuColumn, 0, sizeof(s8) * NUM_ROWS_GAME_MODE_MENU);
+    memset(&gGameModeSubMenuColumn, 0, sizeof(s8) * NUM_COLUMN_GAME_MODE_SUB_MENU * NUM_ROWS_GAME_MODE_SUB_MENU);
+
+    CM_ResetAudio();
+
+    // Close the editor.
+    if (gEditor.IsEnabled()) {
+        gEditor.Disable();
+    }
+
+    // Set the debug menu track browsing index back to zero
+    TrackBrowser::Instance->Reset();
+
+    // Land on the same screen the gSkipIntro setting picks at boot.
+    switch (CVarGetInteger("gSkipIntro", 0)) {
+        case 0:
+            gMenuSelection = HARBOUR_MASTERS_MENU;
+            break;
+        case 1:
+            gMenuSelection = LOGO_INTRO_MENU;
+            break;
+        case 2:
+            gMenuSelection = START_MENU;
+            break;
+        case 3:
+            gMenuSelection = MAIN_MENU;
+            break;
+    }
+
+    // Debug mode override gSkipIntro
+    if (CVarGetInteger("gEnableDebugMode", 0) == true) {
+        gMenuSelection = START_MENU;
+    }
+    // Re-enter through the intro's own transition protocol (see HM_TickIntro):
+    // FADE_MODE_LOGO makes setup_menus rebuild the menu items and start a
+    // fresh fade-in, replacing any in-flight transition that would otherwise
+    // advance the stale screen right after the reset.
+    gMenuFadeType = 0;
+    gFadeModeSelection = FADE_MODE_LOGO;
+}
+
 void push_frame() {
+    ApplyPendingReset();
     GameEngine::StartAudioFrame();
     GameEngine::Instance->StartFrame();
     thread5_iteration();
diff --git a/src/port/Game.h b/src/port/Game.h
index 63ad92a4b..edd1902d8 100644
--- a/src/port/Game.h
+++ b/src/port/Game.h
@@ -35,6 +35,7 @@ extern Registry<ActorInfo, const SpawnParams&> gActorRegistry;
 extern Registry<ItemInfo> gItemRegistry;
 extern DataRegistry<RandomItemTable> gItemTableRegistry;
 World* GetWorld(void); // Retrieve the world instance
+void CM_RequestReset(void); // Queue a game reset; applied at the top of the next game frame
 #endif
 // NOLINTBEGIN(readability-identifier-naming)
 
diff --git a/src/port/ui/Menu.h b/src/port/ui/Menu.h
index f3b2fd3dd..7e84e5d26 100644
--- a/src/port/ui/Menu.h
+++ b/src/port/ui/Menu.h
@@ -62,46 +62,10 @@ class Menu : public GuiWindow {
                                    "Searches all menus for the given text, including tooltips.")) } } }
     };
     virtual void ProcessReset() {
-      gGamestateNext = MAIN_MENU_FROM_QUIT;
-      gIsGamePaused = 0;
-      // Reset credits
-      D_800DC5E4 = 0;
-      gTourComplete = false;
-      SetMarioRaceway();
-      memset(&gGameModeMenuColumn, 0, sizeof(s8) * NUM_ROWS_GAME_MODE_MENU);
-      memset(&gGameModeSubMenuColumn, 0, sizeof(s8) * NUM_COLUMN_GAME_MODE_SUB_MENU * NUM_ROWS_GAME_MODE_SUB_MENU);
-
-      CM_ResetAudio();
-
-      switch(CVarGetInteger("gSkipIntro", 0)) {
-          case 0:
-              gMenuSelection = HARBOUR_MASTERS_MENU;
-              break;
-          case 1:
-              gMenuSelection = LOGO_INTRO_MENU;
-              break;
-          case 2:
-              gMenuSelection = START_MENU;
-              break;
-          case 3:
-              gMenuSelection = MAIN_MENU;
-              break;
-      }
-
-      // Close the editor.
-      if (gEditor.IsEnabled()) {
-          gEditor.Disable();
-      }
-
-      // Set the debug menu track browsing index back to zero
-      TrackBrowser::Instance->Reset();
-
-      // Debug mode override gSkipIntro
-      if (CVarGetInteger("gEnableDebugMode", 0) == true) {
-          gMenuSelection = START_MENU;
-      } else {
-          gMenuSelection = LOGO_INTRO_MENU;
-      }
+      // Only request the reset: it is applied at the top of the next game
+      // frame (ApplyPendingReset in Game.cpp), where it cannot race the menu
+      // state machine mid-fade or be swallowed as a repeated gamestate write.
+      CM_RequestReset();
     }
 
   private: