feat(tui): run TUI as external process

src/nvim/ui.c

@@ -35,6 +35,7 @@
 #include "nvim/ui_compositor.h"
 #include "nvim/vim.h"
 #include "nvim/window.h"
+#include "nvim/msgpack_rpc/channel.h"
 #ifdef FEAT_TUI
 # include "nvim/tui/tui.h"
 #else
@@ -150,6 +151,19 @@ void ui_builtin_start(void)
 #endif
 }
 
+uint64_t ui_client_start(int argc, char **argv, bool pass_stdin)
+{
+  ui_comp_detach(uis[1]);  // Bypassing compositor in client
+  uint64_t rv = ui_client_start_server(argc, argv, pass_stdin);
+  return rv;
+}
+
+UI* ui_get_by_index(int idx)
+{
+  assert(idx < 16);
+  return uis[idx];
+}
+
 bool ui_rgb_attached(void)
 {
   if (!headless_mode && p_tgc) {
@@ -228,6 +242,7 @@ void ui_refresh(void)
     screen_resize(width, height);
     p_lz = save_p_lz;
   } else {
+    // TODO: not like this
     Array args = ARRAY_DICT_INIT;
     ADD(args, INTEGER_OBJ((int)width));
     ADD(args, INTEGER_OBJ((int)height));