From 635acc7dc848853fe4a5db2f0c85dc52e8eabed0 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <62671086+barrettruth@users.noreply.github.com>
Date: Tue, 28 Jul 2026 13:59:18 -0500
Subject: [PATCH] fix(terminal): cursor moves on resize when line above is full
 width #40996

---
 src/nvim/vterm/screen.c                  |  2 +-
 test/functional/terminal/window_spec.lua | 28 ++++++++++++++++++++++++
 test/unit/vterm_spec.lua                 | 22 +++++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/src/nvim/vterm/screen.c b/src/nvim/vterm/screen.c
index 99c8e61748..4e8de11428 100644
--- a/src/nvim/vterm/screen.c
+++ b/src/nvim/vterm/screen.c
@@ -608,7 +608,7 @@ static void resize_buffer(VTermScreen *screen, int bufidx, int new_rows, int new
         count--;
       }
 
-      if (old_cursor.row == old_row && old_cursor.col >= old_col) {
+      if (old_row <= old_row_end && old_cursor.row == old_row && old_cursor.col >= old_col) {
         new_cursor.row = new_row, new_cursor.col = (old_cursor.col - old_col + new_col);
         if (new_cursor.col >= new_cols) {
           new_cursor.col = new_cols - 1;
diff --git a/test/functional/terminal/window_spec.lua b/test/functional/terminal/window_spec.lua
index 978fd921ce..752def3c57 100644
--- a/test/functional/terminal/window_spec.lua
+++ b/test/functional/terminal/window_spec.lua
@@ -16,6 +16,7 @@ local eval = n.eval
 local skip = t.skip
 local is_os = t.is_os
 local testprg = n.testprg
+local api = n.api
 
 describe(':terminal window', function()
   before_each(clear)
@@ -36,6 +37,33 @@ describe(':terminal window', function()
     eq({ 1, 1, 1 }, eval('[&l:list, &list, &g:list]'))
   end)
 
+  it('keeps the cursor put on resize when the line above it is full width', function()
+    local screen = Screen.new(50, 7)
+    local buf = api.nvim_create_buf(true, true)
+    local chan = api.nvim_open_term(buf, {})
+    api.nvim_win_set_buf(0, buf)
+    feed('i')
+    api.nvim_chan_send(chan, 'l1\r\nl2\r\nl3\r\nl4\r\n' .. ('A'):rep(50) .. '\r\nX')
+    screen:expect([[
+      l1                                                |
+      l2                                                |
+      l3                                                |
+      l4                                                |
+      AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA|
+      X^                                                 |
+      {5:-- TERMINAL --}                                    |
+    ]])
+    screen:try_resize(50, 6)
+    screen:expect([[
+      l2                                                |
+      l3                                                |
+      l4                                                |
+      AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA|
+      X^                                                 |
+      {5:-- TERMINAL --}                                    |
+    ]])
+  end)
+
   it('resets horizontal scroll on resize #35331', function()
     skip(is_os('win'), 'Too flaky on Windows')
     local screen = tt.setup_screen(0, { testprg('shell-test'), 'INTERACT' })
diff --git a/test/unit/vterm_spec.lua b/test/unit/vterm_spec.lua
index 27cf65c34c..da118d33b4 100644
--- a/test/unit/vterm_spec.lua
+++ b/test/unit/vterm_spec.lua
@@ -3800,6 +3800,28 @@ putglyph 1f3f4,200d,2620,fe0f 2 0,4]])
     push('\x1b[2;1Habc\r\n\x1b[H', vt)
     resize(1, 1, vt)
     cursor(0, 0, state)
+
+    reset(state, screen)
+    resize(4, 4, vt)
+    push('ABCD\r\nX', vt)
+    screen_row(0, 'ABCD', screen, vt.cols)
+    screen_row(1, 'X', screen, vt.cols)
+    cursor(1, 1, state)
+    resize(4, 5, vt)
+    screen_row(0, 'ABCD', screen, vt.cols)
+    screen_row(1, 'X', screen, vt.cols)
+    cursor(1, 1, state)
+
+    reset(state, screen)
+    resize(4, 4, vt)
+    push('ABCD\r\nX', vt)
+    cursor(1, 1, state)
+    resize(3, 4, vt)
+    screen_row(0, 'ABCD', screen, vt.cols)
+    screen_row(1, 'X', screen, vt.cols)
+    cursor(1, 1, state)
+
+    resize(5, 10, vt)
   end)
 
   pending('90vttest_01-movement-1', function() end)