Add replay-safe host UI actions and graceful exit

runner/src/desktop/host_api.h

@@ -29,6 +29,17 @@ extern SDL_Window *g_window;
  * pulling in this one. */
 extern bool g_config_dirty;
 
+/* Game-owned host UI may change persistent presentation settings only while
+ * this is true. Speculative frames and netplay rollback replay must not
+ * change a window, write settings or perform application actions. */
+bool snesrecomp_host_frame_is_live(void);
+
+/* Request a normal application shutdown at the host's next event poll.
+ * Returns to the caller; configuration, SRAM and host resources follow the
+ * same shutdown path as closing the window. Call after SDL initialization.
+ * Speculative frames and netplay rollback replays cannot request an exit. */
+void snesrecomp_request_exit(void);
+
 /* Enables or disables fullscreen/borderless mode from dependent project code.
  * Clamps mode to {0,1}: 0 = windowed, 1 = borderless
  * (SNESRECOMP_SDL_WINDOW_FULLSCREEN_DESKTOP).

runner/src/desktop/host_main.c

@@ -418,6 +418,20 @@ static int g_savestate_menu_hotkey;
 static int g_rewind_hotkey;
 static int g_open_launcher_hotkey;   /* in_game_launcher only */
 static uint64_t g_state_generation;
+static bool g_host_replaying_frame;
+
+bool snesrecomp_host_frame_is_live(void) {
+  return !RtlSpeculativeFrame() && !g_host_replaying_frame;
+}
+
+void snesrecomp_request_exit(void) {
+  if (!snesrecomp_host_frame_is_live()) return;
+  SDL_Event event;
+  memset(&event, 0, sizeof(event));
+  event.type = SDL_QUIT;
+  if (SDL_PushEvent(&event) <= 0)
+    host_report_breadcrumb("host exit request could not be queued: %s", SDL_GetError());
+}
 
 /* The last field actually presented, kept so an overlay can freeze the guest
  * and still have something to draw behind itself. Sized like g_my_pixels. */
@@ -1270,9 +1284,12 @@ static void CaptureSimulationFrame(unsigned number) {
 
 #if defined(SNESRECOMP_NET_ROLLBACK)
 static void NetplayReplayFrame(uint32_t inputs, uint32_t tick) {
+  bool was_replaying = g_host_replaying_frame;
+  g_host_replaying_frame = true;
   if (g_game->before_run_frame) g_game->before_run_frame();
   RtlRunFrame(inputs);
   CaptureSimulationFrame(tick + 1);
+  g_host_replaying_frame = was_replaying;
 }
 #endif
 

runner/tests/test_host_exit_api.py

@@ -0,0 +1,85 @@
+"""Exercise the real host exit API against SDL's event queue.
+
+ELF section collection lets this small fixture include the actual desktop
+implementation without linking an entire title. Windows coverage comes from
+the built-title shutdown check; PE retains unrelated host references here.
+"""
+import os
+from pathlib import Path
+import shlex
+import shutil
+import subprocess
+import sys
+
+import pytest
+
+
+ROOT = Path(__file__).resolve().parents[2]
+
+
+@pytest.mark.skipif(sys.platform != "linux", reason="ELF host fixture")
+@pytest.mark.parametrize("sdl", ["sdl2", "sdl3"])
+def test_exit_uses_normal_events_and_ignores_replay(tmp_path, sdl):
+    cc = shutil.which("cc")
+    pkg = shutil.which("pkg-config")
+    if not cc or not pkg:
+        pytest.skip("C compiler and pkg-config required")
+    available = subprocess.run([pkg, "--exists", sdl], check=False)
+    if available.returncode:
+        pytest.skip(f"{sdl} development package required")
+    source = tmp_path / "exit_test.c"
+    source.write_text(r'''
+#ifdef NDEBUG
+#undef NDEBUG
+#endif
+#include <stdarg.h>
+#include "desktop/host_main.c"
+static bool test_speculative;
+bool RtlSpeculativeFrame(void) { return test_speculative; }
+void host_report_breadcrumb(const char *fmt, ...) { (void)fmt; }
+int main(void) {
+#if SNESRECOMP_SDL3
+  assert(SDL_Init(SDL_INIT_EVENTS));
+#else
+  assert(SDL_Init(SDL_INIT_EVENTS) == 0);
+#endif
+  SDL_Event event;
+  while (SDL_PollEvent(&event)) {}
+  assert(snesrecomp_host_frame_is_live());
+  test_speculative = true;
+  assert(!snesrecomp_host_frame_is_live());
+  snesrecomp_request_exit();
+  assert(!SDL_PollEvent(&event));
+  test_speculative = false;
+  g_host_replaying_frame = true;
+  assert(!snesrecomp_host_frame_is_live());
+  snesrecomp_request_exit();
+  assert(!SDL_PollEvent(&event));
+  g_host_replaying_frame = false;
+  assert(snesrecomp_host_frame_is_live());
+  snesrecomp_request_exit();
+  assert(SDL_PollEvent(&event));
+  assert(event.type == SDL_QUIT);
+  assert(!SDL_PollEvent(&event));
+  SDL_Quit();
+  return 0;
+}
+''', encoding="utf-8")
+    flags = shlex.split(subprocess.check_output(
+        [pkg, "--cflags", "--libs", sdl], text=True))
+    executable = tmp_path / "exit_test"
+    subprocess.run([
+        cc, "-std=gnu11", "-O2", "-ffunction-sections", "-fdata-sections",
+        f"-DSNESRECOMP_SDL3={int(sdl == 'sdl3')}",
+        f"-DLNG_SDL3={int(sdl == 'sdl3')}", "-DSDL_MAIN_HANDLED",
+        "-I" + str(ROOT / "runner/src"),
+        "-I" + str(ROOT / "runner/src/snes"),
+        "-I" + str(ROOT / "runner/src/desktop"),
+        "-I" + str(ROOT / "third_party"),
+        "-I" + str(ROOT / "third_party/gl_core"),
+        str(source), "-Wl,--gc-sections", *flags, "-lm", "-o", str(executable),
+    ], check=True, capture_output=True, text=True, timeout=60)
+    env = os.environ.copy()
+    env["LD_LIBRARY_PATH"] = subprocess.check_output(
+        [pkg, "--variable=libdir", sdl], text=True).strip()
+    subprocess.run([str(executable)], env=env, check=True, timeout=15)