fix(pathfinder): remove dead/misleading error handling in platform loaders

cuda_pathfinder/cuda/pathfinder/_dynamic_libs/load_dl_linux.py

@@ -165,17 +165,19 @@ def load_with_system_search(desc: LibDescriptor) -> LoadedDL | None:
         A LoadedDL object if successful, None if the library cannot be loaded
 
     Raises:
-        RuntimeError: If the library is loaded but no expected symbol is found
+        OSError: If the library is loaded but its absolute path cannot be
+            resolved via dlinfo (surfaced from abs_path_for_dynamic_library).
     """
     for soname in _candidate_sonames(desc):
         try:
             handle = _load_lib(desc, soname)
         except OSError:
             pass
         else:
+            # abs_path_for_dynamic_library never returns None: it returns a
+            # resolved path or raises OSError. Let that error surface rather
+            # than masking it, consistent with the deterministic-loader policy.
             abs_path = abs_path_for_dynamic_library(desc.name, handle)
-            if abs_path is None:
-                raise RuntimeError(f"No expected symbol for libname={desc.name!r}")
             return LoadedDL(abs_path, False, handle._handle, "system-search")
     return None
 

cuda_pathfinder/cuda/pathfinder/_dynamic_libs/load_dl_windows.py

@@ -69,11 +69,10 @@ def add_dll_directory(dll_abs_path: str) -> None:
     dirpath = os.path.dirname(dll_abs_path)
     assert os.path.isdir(dirpath), dll_abs_path
 
-    # Add the DLL directory to the search path
-    result = kernel32.AddDllDirectory(dirpath)
-    if not result:
-        # Fallback: just update PATH if AddDllDirectory fails
-        pass
+    # Add the DLL directory to the native search path. AddDllDirectory only
+    # affects the LOAD_LIBRARY_SEARCH_USER_DIRS search; PATH is updated
+    # unconditionally below to also cover legacy dependent-DLL resolution.
+    kernel32.AddDllDirectory(dirpath)
 
     # Update PATH as a fallback for dependent DLL resolution
     curr_path = os.environ.get("PATH")