runtime: expose the resolved window-icon path for the launcher

recomp-ui takes a host-supplied icon path (GameInfo.window_icon_path) so the
launcher window carries the same art as the game window. Publish the path
psx_apply_window_icon() already resolves, rather than letting the launcher
repeat the search — repeating it is what would let the two drift apart the
next time the candidate list changes.

Resolved once and cached: both the game window and the launcher ask, and the
answer cannot change within a run.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0194TYJAqgyG9a9PJe9uUcgQ

runtime/include/psx_window_icon.h

@@ -10,6 +10,14 @@ struct SDL_Window;
  * the window / taskbar icon. No-op when the PNG is missing. */
 void psx_apply_window_icon(struct SDL_Window *window, const char *argv0);
 
+/* The resolved path psx_apply_window_icon() would use, or "" when no icon PNG
+ * was found. Exists so the launcher can carry the SAME icon as the game
+ * window: recomp-ui takes a host-supplied path (GameInfo.window_icon_path)
+ * rather than repeating this search, which is what stops the two from
+ * drifting apart the next time the search order changes. The result is cached
+ * on first call and the returned pointer stays valid for the process. */
+const char *psx_window_icon_path(const char *argv0);
+
 #ifdef __cplusplus
 }
 #endif

runtime/src/main.cpp

@@ -10734,6 +10734,14 @@ namespace {
         gi->memcard_inspect = ae_memcard_inspect;
         gi->mods = PSXRecompV4::mod_runtime_launcher_provider();
         gi->bios_verify = ae_bios_verify;
+        /* Launcher window icon: the SAME file psx_apply_window_icon() puts on
+         * the game window (assets/psxrecomp.png beside the exe, which
+         * runtime.cmake stages from APP_ICON's directory). Resolved through
+         * the shared helper rather than re-derived here, so the launcher and
+         * the game can never end up on different art. The pointer is process-
+         * lifetime; "" when the build shipped no PNG, which recomp-ui treats
+         * as "leave the toolkit default". */
+        gi->window_icon_path = psx_window_icon_path(g_lnch_argv0);
 #if defined(PSX_HAS_RECOMP_NET) && defined(PSX_HAS_LOBBY_CLIENT)
         g_lnch_game_players = game_players_n;
         /* ae_disc_verify only fills netplay_ok/disc_fp when this is true. */

runtime/src/psx_window_icon.cpp

@@ -69,10 +69,23 @@ static fs::path find_icon_png(const char *argv0)
     return {};
 }
 
+/* Resolve once and keep it: both the game window and the launcher ask, and
+ * the answer cannot change within a run. */
+extern "C" const char *psx_window_icon_path(const char *argv0)
+{
+    static std::string cached;
+    static bool resolved = false;
+    if (!resolved) {
+        cached = find_icon_png(argv0).string();
+        resolved = true;
+    }
+    return cached.c_str();
+}
+
 extern "C" void psx_apply_window_icon(SDL_Window *window, const char *argv0)
 {
     if (!window) return;
-    const fs::path png = find_icon_png(argv0);
+    const fs::path png(psx_window_icon_path(argv0));
     if (png.empty()) return;
 
     FILE *f = std::fopen(png.string().c_str(), "rb");