diff --git a/firmware/application/external/waterfall_designer/ui_waterfall_designer.hpp b/firmware/application/external/waterfall_designer/ui_waterfall_designer.hpp
index e1fadf5fe..36cf2ebf4 100644
--- a/firmware/application/external/waterfall_designer/ui_waterfall_designer.hpp
+++ b/firmware/application/external/waterfall_designer/ui_waterfall_designer.hpp
@@ -217,18 +217,31 @@ class WaterfallDesignerView : public View {
     void restore_current_profile();
     void on_create_new_profile();
     void on_open_profile();
-    void on_profile_changed(std::filesystem::path new_profile_path);
+    void on_profile_changed(const std::filesystem::path& new_profile_path);
     void on_save_profile();
     void on_add_level();
     void on_remove_level();
     void on_edit_color();
 
+    /* Each of these owns the only File in its call chain. Keeping them as
+     * separate frames matters: a File carries a 512 byte FIL sector cache
+     * (_FS_TINY is 0) and the M0 process stack is 4kB, so if read_profile_file
+     * merged into on_profile_changed its 784 byte frame would stay live across
+     * the copy_file() in on_apply_current_to_wtf() - 3.6kB of 4kB instead of
+     * 2.8kB. GCC does not inline them at -O2 today; noinline just pins that so
+     * a heuristic change can't quietly eat the headroom. */
+    __attribute__((noinline)) bool read_profile_file(const std::filesystem::path& path);
+    __attribute__((noinline)) bool write_profile_file(const std::filesystem::path& path);
+
     void refresh_menu_view();
 
     void on_apply_current_to_wtf();  // will restore if didn't apple, when distruct
     void on_apply_setting();         // apply set
 
     bool if_apply_setting{false};
+    bool backup_attempted_{false};
+    bool profile_backed_up_{false};
+    std::filesystem::path pending_profile_path{};  // set by the New dialog, consumed on_pop
     /*NB:
     this works as:
     each time you change color, it apply as file realtime