fix(ui): command line issues with external messages (#21709)

* fix: don't truncate external messages
* fix: avoid resizing command line with external messages

2 files changed, 13 insertions, 7 deletions

diff --git a/src/nvim/message.c b/src/nvim/message.c
index e9d66ea184..de4acd601f 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -919,9 +919,11 @@ char *msg_trunc_attr(char *s, bool force, int attr)
 /// @note: May change the message by replacing a character with '<'.
 char *msg_may_trunc(bool force, char *s)
 {
-  int room;
+  if (ui_has(kUIMessages)) {
+    return s;
+  }
 
-  room = (Rows - cmdline_row - 1) * Columns + sc_col - 1;
+  int room = (Rows - cmdline_row - 1) * Columns + sc_col - 1;
   if ((force || (shortmess(SHM_TRUNC) && !exmode_active))
       && (int)strlen(s) - room > 0) {
     int size = vim_strsize(s);
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 37f297909a..2bcbef14b0 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -5780,6 +5780,10 @@ static void frame_setheight(frame_T *curfrp, int height)
 
   if (curfrp->fr_parent == NULL) {
     // topframe: can only change the command line height
+    // Avoid doing so with external messages.
+    if (ui_has(kUIMessages)) {
+      return;
+    }
     if (height > ROWS_AVAIL) {
       // If height is greater than the available space, try to create space for
       // the frame by reducing 'cmdheight' if possible, while making sure
@@ -6115,13 +6119,13 @@ void win_setminwidth(void)
 /// Status line of dragwin is dragged "offset" lines down (negative is up).
 void win_drag_status_line(win_T *dragwin, int offset)
 {
-  // If the user explicitly set 'cmdheight' to zero, then allow for dragging
-  // the status line making it zero again.
-  if (p_ch == 0) {
-    p_ch_was_zero = true;
+  frame_T *fr = dragwin->w_frame;
+
+  // Avoid changing command line height with external messages.
+  if (fr->fr_next == NULL && ui_has(kUIMessages)) {
+    return;
   }
 
-  frame_T *fr = dragwin->w_frame;
   frame_T *curfr = fr;
   if (fr != topframe) {         // more than one window
     fr = fr->fr_parent;