From ed7ff848a02d37975dd56c2d67e0fe23e75f68dd Mon Sep 17 00:00:00 2001
From: Shadman <shadmansaleh3@gmail.com>
Date: Mon, 30 Jun 2025 16:19:43 +0600
Subject: [PATCH] fix(prompt): prompt mark not placed after text edits
 correctly #34671

---
 src/nvim/api/buffer.c                         |  2 +-
 src/nvim/edit.c                               |  1 +
 src/nvim/eval.c                               |  4 +-
 test/functional/legacy/prompt_buffer_spec.lua | 76 +++++++++++++++++++
 4 files changed, 80 insertions(+), 3 deletions(-)

diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 6f6076c29b..f6431fec33 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -663,7 +663,7 @@ void nvim_buf_set_text(uint64_t channel_id, Buffer buffer, Integer start_row, In
     // changed range, and move any in the remainder of the buffer.
     // Do not adjust any cursors. need to use column-aware logic (below)
     linenr_T adjust = end_row >= start_row ? MAXLNUM : 0;
-    mark_adjust_buf(buf, (linenr_T)start_row, (linenr_T)end_row, adjust, (linenr_T)extra,
+    mark_adjust_buf(buf, (linenr_T)start_row, (linenr_T)end_row - 1, adjust, (linenr_T)extra,
                     true, true, kExtmarkNOOP);
 
     extmark_splice(buf, (int)start_row - 1, (colnr_T)start_col,
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index d27c175ecd..b1d32156c9 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -1545,6 +1545,7 @@ static void init_prompt(int cmdchar_todo)
       ml_replace(curbuf->b_ml.ml_line_count, prompt, true);
     } else {
       ml_append(curbuf->b_ml.ml_line_count, prompt, 0, false);
+      curbuf->b_prompt_start.mark.lnum += 1;
     }
     curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
     coladvance(curwin, MAXCOL);
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 981a1319fc..59421c24f7 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -8702,6 +8702,7 @@ void prompt_invoke_callback(void)
   appended_lines_mark(lnum, 1);
   curwin->w_cursor.lnum = lnum + 1;
   curwin->w_cursor.col = 0;
+  curbuf->b_prompt_start.mark.lnum = lnum + 1;
 
   if (curbuf->b_prompt_callback.type == kCallbackNone) {
     xfree(user_input);
@@ -8720,8 +8721,7 @@ theend:
   // clear undo history on submit
   u_clearallandblockfree(curbuf);
 
-  pos_T next_prompt = { .lnum = curbuf->b_ml.ml_line_count, .col = 1, .coladd = 0 };
-  RESET_FMARK(&curbuf->b_prompt_start, next_prompt, 0, ((fmarkv_T)INIT_FMARKV));
+  curbuf->b_prompt_start.mark.lnum = curbuf->b_ml.ml_line_count;
 }
 
 /// @return  true when the interrupt callback was invoked.
diff --git a/test/functional/legacy/prompt_buffer_spec.lua b/test/functional/legacy/prompt_buffer_spec.lua
index d88aa6858f..176470f248 100644
--- a/test/functional/legacy/prompt_buffer_spec.lua
+++ b/test/functional/legacy/prompt_buffer_spec.lua
@@ -12,6 +12,7 @@ local poke_eventloop = n.poke_eventloop
 local api = n.api
 local eq = t.eq
 local neq = t.neq
+local exec_lua = n.exec_lua
 
 describe('prompt buffer', function()
   local screen
@@ -596,4 +597,79 @@ describe('prompt buffer', function()
       eq('', fn('prompt_getinput', bufnr))
     end)
   end)
+
+  it('programmatic (non-user) edits', function()
+    api.nvim_set_option_value('buftype', 'prompt', { buf = 0 })
+
+    -- with nvim_buf_set_lines
+    exec_lua([[
+      local buf = vim.api.nvim_get_current_buf()
+      vim.fn.prompt_setcallback(buf, function(text)
+        vim.api.nvim_buf_set_lines(buf, -2, -2, true, vim.split(text, '\n'))
+      end)
+    ]])
+    feed('iset_lines<cr>')
+    feed('set_lines2<cr>')
+    screen:expect([[
+      % set_lines              |
+      set_lines                |
+      % set_lines2             |
+      set_lines2               |
+      % ^                       |
+      {1:~                        }|*4
+      {5:-- INSERT --}             |
+    ]])
+
+    feed('set_lines3(multi-1)<s-cr>set_lines3(multi-2)<cr>')
+    screen:expect([[
+      % set_lines              |
+      set_lines                |
+      % set_lines2             |
+      set_lines2               |
+      % set_lines3(multi-1)    |
+      set_lines3(multi-2)      |
+      set_lines3(multi-1)      |
+      set_lines3(multi-2)      |
+      % ^                       |
+      {5:-- INSERT --}             |
+    ]])
+    -- with nvim_buf_set_text
+    source('bwipeout!')
+    api.nvim_set_option_value('buftype', 'prompt', { buf = 0 })
+    exec_lua([[
+      local buf = vim.api.nvim_get_current_buf()
+      vim.fn.prompt_setcallback(buf, function(text)
+        local lines = vim.split(text, '\n')
+        if lines[#lines] ~= '' then
+          table.insert(lines, '')
+        end
+        vim.api.nvim_buf_set_text(buf, -1, 0, -1, 0, lines)
+      end)
+    ]])
+    feed('set_text<cr>')
+    feed('set_text2<cr>')
+    screen:expect([[
+      % set_text               |
+      set_text                 |
+      % set_text2              |
+      set_text2                |
+      % ^                       |
+      {1:~                        }|*4
+      {5:-- INSERT --}             |
+    ]])
+
+    feed('set_text3(multi-1)<s-cr>set_text3(multi-2)<cr>')
+    screen:expect([[
+      % set_text               |
+      set_text                 |
+      % set_text2              |
+      set_text2                |
+      % set_text3(multi-1)     |
+      set_text3(multi-2)       |
+      set_text3(multi-1)       |
+      set_text3(multi-2)       |
+      % ^                       |
+      {5:-- INSERT --}             |
+    ]])
+  end)
 end)