fix(terminal): missing refresh with partial mappings (#37839)

Problem:  Terminal buffers are not refreshed when processing keys that
          trigger partial mappings.
Solution: Process due terminal refreshes before redrawing.

src/nvim/normal.c

@@ -82,6 +82,7 @@
 #include "nvim/strings.h"
 #include "nvim/syntax.h"
 #include "nvim/tag.h"
+#include "nvim/terminal.h"
 #include "nvim/textformat.h"
 #include "nvim/textobject.h"
 #include "nvim/types_defs.h"
@@ -1445,6 +1446,8 @@ static int normal_check(VimState *state)
     skip_redraw = false;
     setcursor();
   } else if (do_redraw || stuff_empty()) {
+    terminal_check_refresh();
+
     // Ensure curwin->w_topline and curwin->w_leftcol are up to date
     // before triggering a WinScrolled autocommand.
     update_topline(curwin);

src/nvim/terminal.c

@@ -746,7 +746,7 @@ void terminal_set_state(Terminal *term, bool suspended)
 {
   if (term->suspended != suspended) {
     // Trigger a main loop iteration to redraw the buffer.
-    multiqueue_put(main_loop.events, terminal_state_change_event,
+    multiqueue_put(refresh_timer.events, terminal_state_change_event,
                    (void *)(intptr_t)term->buf_handle);
   }
   term->suspended = suspended;
@@ -1033,6 +1033,8 @@ static int terminal_check(VimState *state)
     return 0;
   }
 
+  terminal_check_refresh();
+
   // Validate topline and cursor position for autocommands. Especially important for WinScrolled.
   terminal_check_cursor();
   validate_cursor(curwin);
@@ -2283,6 +2285,14 @@ static void invalidate_terminal(Terminal *term, int start_row, int end_row)
   }
 }
 
+/// Normally refresh_timer_cb() is called when processing main_loop.events, but with
+/// partial mappings main_loop.events isn't processed, while terminal buffers still
+/// need refreshing after processing a key, so call this function before redrawing.
+void terminal_check_refresh(void)
+{
+  multiqueue_process_events(refresh_timer.events);
+}
+
 static void refresh_terminal(Terminal *term)
 {
   buf_T *buf = handle_get_buffer(term->buf_handle);

test/functional/terminal/buffer_spec.lua

@@ -296,6 +296,64 @@ describe(':terminal buffer', function()
     eq('t', fn.mode(1))
   end)
 
+  it('is refreshed with partial mappings in Terminal mode #9167', function()
+    command([[set timeoutlen=20000 | tnoremap jk <C-\><C-N>]])
+    feed('j') -- Won't reach the terminal until the next character is typed
+    screen:expect_unchanged()
+    feed('j') -- Refresh scheduled for the first 'j' but not processed
+    screen:expect_unchanged()
+    for i = 1, 10 do
+      eq({ mode = 't', blocking = true }, api.nvim_get_mode())
+      vim.uv.sleep(10) -- Wait for the previously scheduled refresh timer to arrive
+      feed('j') -- Refresh scheduled for the last 'j' and processed for the one before
+      screen:expect(([[
+        tty ready                                         |
+        %s^%s|
+                                                          |*4
+        {5:-- TERMINAL --}                                    |
+      ]]):format(('j'):rep(i), (' '):rep(50 - i)))
+    end
+    feed('l') -- No partial mapping, so all pending refreshes should be processed
+    screen:expect([[
+      tty ready                                         |
+      jjjjjjjjjjjjl^                                     |
+                                                        |*4
+      {5:-- TERMINAL --}                                    |
+    ]])
+  end)
+
+  it('is refreshed with partial mappings in Normal mode', function()
+    command('set timeoutlen=20000 | nnoremap jk :')
+    command('nnoremap j <Cmd>call chansend(&channel, "j")<CR>')
+    feed([[<C-\><C-N>]])
+    screen:expect([[
+      tty ready                                         |
+      ^                                                  |
+                                                        |*5
+    ]])
+    feed('j') -- Won't reach the terminal until the next character is typed
+    screen:expect_unchanged()
+    feed('j') -- Refresh scheduled for the first 'j' but not processed
+    screen:expect_unchanged()
+    for i = 1, 10 do
+      eq({ mode = 'nt', blocking = true }, api.nvim_get_mode())
+      vim.uv.sleep(10) -- Wait for the previously scheduled refresh timer to arrive
+      feed('j') -- Refresh scheduled for the last 'j' and processed for the one before
+      screen:expect(([[
+        tty ready                                         |
+        ^%s%s|
+                                                          |*4
+                                                          |
+      ]]):format(('j'):rep(i), (' '):rep(50 - i)))
+    end
+    feed('l') -- No partial mapping, so all pending refreshes should be processed
+    screen:expect([[
+      tty ready                                         |
+      j^jjjjjjjjjjj                                      |
+                                                        |*5
+    ]])
+  end)
+
   it('writing to an existing file with :w fails #13549', function()
     eq(
       'Vim(write):E13: File exists (add ! to override)',