From e2c0c634522b7742ef0fb0018bca8b373cf35417 Mon Sep 17 00:00:00 2001
From: Tanishq <139997424+dev-tnsq@users.noreply.github.com>
Date: Wed, 5 Aug 2026 23:05:09 +0530
Subject: [PATCH] fix(statusline): don't clobber global statusline during
 autocmd #41169

Problem:
With `laststatus=3`, a pager float shares the main grid's statusline
row. Setting a diagnostic fires `DiagnosticChanged`, whose handler calls
`nvim__redraw({ statusline = true })`.

Analysis:
Inside the autocmd, `curwin` is temporarily switched to the tiled window
showing that buffer, so `win_redr_status()` paints its statusline over
the pager's `[Pager]` statusline on the shared row. After the autocmd,
`curwin` is restored but the pager statusline is never repainted.

Solution:
Use `ctx_saved_curwin()` decide whether to draw the global statusline,
matching `win_redr_stl_expr()` and `update_screen()`. No behavior change
if no buffer-context switch is active.
---
 src/nvim/statusline.c                 | 12 ++++++++++--
 test/functional/ui/messages2_spec.lua | 22 ++++++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/nvim/statusline.c b/src/nvim/statusline.c
index 3a7f0cd0fd..fd089aa9e5 100644
--- a/src/nvim/statusline.c
+++ b/src/nvim/statusline.c
@@ -91,14 +91,22 @@ void win_redr_status(win_T *wp)
 
   busy = true;
   wp->w_redr_status = false;
-  if (wp->w_status_height == 0 && !(is_stl_global && wp == curwin)) {
+
+  // curwin may be temporarily switched during autocmds (ctx_switch).
+  win_T *stl_curwin = ctx_saved_curwin();
+  if (stl_curwin == NULL) {
+    stl_curwin = curwin;
+  }
+  bool is_stl_curwin = wp == stl_curwin;
+
+  if (wp->w_status_height == 0 && !(is_stl_global && is_stl_curwin)) {
     // no status line, either global statusline is enabled or the window is a last window
     redraw_cmdline = true;
   } else if (!redrawing()) {
     // Don't redraw right now, do it later. Don't update status line when
     // popup menu is visible and may be drawn over it
     wp->w_redr_status = true;
-  } else if (*wp->w_p_stl != NUL || !wp->w_floating || (is_stl_global && wp == curwin)) {
+  } else if (*wp->w_p_stl != NUL || !wp->w_floating || (is_stl_global && is_stl_curwin)) {
     win_redr_stl_expr(wp, false, false, false);
   }
 
diff --git a/test/functional/ui/messages2_spec.lua b/test/functional/ui/messages2_spec.lua
index f600cd8ed4..56f20f37cd 100644
--- a/test/functional/ui/messages2_spec.lua
+++ b/test/functional/ui/messages2_spec.lua
@@ -1259,4 +1259,26 @@ describe('messages2', function()
       ----------------------------------------------------0|
     ]])
   end)
+
+  it('pager statusline is not clobbered by DiagnosticChanged redraw #41130', function()
+    exec_lua(function()
+      vim.o.laststatus = 3
+      vim.print('message')
+      vim.cmd.mes()
+    end)
+    screen:expect([[
+                                                           |
+      {1:~                                                    }|*9
+      {3:                                                     }|
+      ^message                                              |
+      {3:[Pager]                                              }|
+      message                                              |
+    ]])
+    exec_lua(function()
+      vim.diagnostic.config({ signs = false, virtual_text = false, underline = false })
+      local ns = vim.api.nvim_create_namespace('repro-41130')
+      vim.diagnostic.set(ns, 1, { { lnum = 0, message = 'random error' } }, {})
+    end)
+    screen:expect_unchanged()
+  end)
 end)