3 files changed, 14 insertions, 2 deletions
diff --git a/src/nvim/api/ui.c b/src/nvim/api/ui.c
index b77516d588..a934f18dbf 100644
--- a/src/nvim/api/ui.c
+++ b/src/nvim/api/ui.c
@@ -210,8 +210,9 @@ static void ui_set_option(UI *ui, bool init, String name, Object value,
       return;
     }
     ui->rgb = value.data.boolean;
-    // A little drastic, but only legacy uis need to use this option
-    if (!init) {
+    // A little drastic, but only takes effect for legacy uis. For linegrid UI
+    // only changes metadata for nvim_list_uis(), no refresh needed.
+    if (!init && !ui->ui_ext[kUILinegrid]) {
       ui_refresh();
     }
     return;
@@ -355,6 +356,12 @@ static void remote_ui_default_colors_set(UI *ui, Integer rgb_fg,
                                          Integer rgb_bg, Integer rgb_sp,
                                          Integer cterm_fg, Integer cterm_bg)
 {
+  if (!ui->ui_ext[kUITermColors]) {
+    bool dark = (*p_bg == 'd');
+    rgb_fg = rgb_fg != -1 ? rgb_fg : (dark ? 0xFFFFFF : 0x000000);
+    rgb_bg = rgb_bg != -1 ? rgb_bg : (dark ? 0x000000 : 0xFFFFFF);
+    rgb_sp = rgb_sp != -1 ? rgb_sp : 0xFF0000;
+  }
   Array args = ARRAY_DICT_INIT;
   ADD(args, INTEGER_OBJ(rgb_fg));
   ADD(args, INTEGER_OBJ(rgb_bg));
diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index 6a7cbd36cc..9b2f9c6fe6 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -310,6 +310,9 @@ void ui_set_ext_option(UI *ui, UIExtension ext, bool active)
     ui->option_set(ui, cstr_as_string((char *)ui_ext_names[ext]),
                    BOOLEAN_OBJ(active));
   }
+  if (ext == kUITermColors) {
+    ui_default_colors_set();
+  }
 }
 
 void ui_line(ScreenGrid *grid, int row, int startcol, int endcol, int clearcol,
diff --git a/src/nvim/ui.h b/src/nvim/ui.h
index a5a0fa8b75..49a30fe78b 100644
--- a/src/nvim/ui.h
+++ b/src/nvim/ui.h
@@ -18,6 +18,7 @@ typedef enum {
   kUILinegrid,
   kUIMultigrid,
   kUIHlState,
+  kUITermColors,
   kUIExtCount,
 } UIExtension;
 
@@ -29,6 +30,7 @@ EXTERN const char *ui_ext_names[] INIT(= {
   "ext_linegrid",
   "ext_multigrid",
   "ext_hlstate",
+  "ext_termcolors",
 });