Preserve explicit recomp UI root

recompiler/CMakeLists.txt

@@ -610,6 +610,7 @@ if(BUILD_TESTING)
                 release_zip
                 overlay_decodable_fallback
                 overlay_init_guard
+                recomp_ui_root_override
                 pal_cadence_host_refresh
                 sdl3_main_single_include
                 spu_sample_scheduler_default

runtime/runtime.cmake

@@ -1878,8 +1878,9 @@ function(psxrecomp_add_game_runtime target)
             "-DPSX_GAME_VERSION=${_psxg_release_version} or delete the build cache.")
     endif()
 
-    # Prefer game-root recomp-ui (runtime.cmake also auto-discovers this).
-    if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/recomp-ui/recomp_ui.cmake")
+    # Use a game-root recomp-ui only when the caller did not select one.
+    if((NOT RECOMP_UI_ROOT OR RECOMP_UI_ROOT STREQUAL "")
+       AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/recomp-ui/recomp_ui.cmake")
         set(RECOMP_UI_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/recomp-ui" CACHE PATH
             "Path to recomp-ui launcher" FORCE)
     endif()

runtime/tests/test_recomp_ui_root_override.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+"""Guard the caller-selected recomp-ui root against game-root replacement."""
+
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[2]
+RUNTIME_CMAKE = ROOT / "runtime" / "runtime.cmake"
+
+
+def main() -> None:
+    text = RUNTIME_CMAKE.read_text(encoding="utf-8")
+    expected = """if((NOT RECOMP_UI_ROOT OR RECOMP_UI_ROOT STREQUAL \"\")
+       AND EXISTS \"${CMAKE_CURRENT_SOURCE_DIR}/recomp-ui/recomp_ui.cmake\")"""
+    assert expected in text, (
+        "runtime packaging must preserve an explicit RECOMP_UI_ROOT before "
+        "falling back to the game-root recomp-ui"
+    )
+
+
+if __name__ == "__main__":
+    main()