From f61b15b28426726de92fc970bf9b218c08913811 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 26 Jul 2025 09:25:01 +0530
Subject: [PATCH] Fix incorrect handling of VS16 when it causes char to wrap to
 next line and is part of a draw command with more characters following it

Needed to initialize full text loop state rather than just segmentation
state on wrap. Fixes #8848
---
 docs/changelog.rst    |  2 ++
 kitty/screen.c        | 11 ++++++-----
 kitty_tests/screen.py |  4 ++++
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index af114e0c1..0053714dd 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -122,6 +122,8 @@ Detailed list of changes
 
 - Watchers: A new event for global watchers corresponding to the tab bar being changed (:disc:`8842`)
 
+- Fix a regression in 0.40.0 that broke handing of the VS16 variation selector when it caused a character to reflow to the next line (:iss:`8848`)
+
 0.42.2 [2025-07-16]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/kitty/screen.c b/kitty/screen.c
index 1f18a110a..c9bd6e08e 100644
--- a/kitty/screen.c
+++ b/kitty/screen.c
@@ -944,7 +944,8 @@ move_cursor_past_multicell(Screen *self, index_type required_width) {
 }
 
 static void
-move_widened_char_past_multiline_chars(Screen *self, CPUCell* cpu_cell, GPUCell *gpu_cell, index_type xpos, index_type ypos) {
+move_widened_char_past_multiline_chars(Screen *self, text_loop_state *s, CPUCell* cpu_cell, GPUCell *gpu_cell, index_type xpos, index_type ypos) {
+    index_type before = self->cursor->y;
     self->cursor->x = xpos; self->cursor->y = ypos;
     if (move_cursor_past_multicell(self, 2)) {
         CPUCell *cp; GPUCell *gp;
@@ -957,6 +958,8 @@ move_widened_char_past_multiline_chars(Screen *self, CPUCell* cpu_cell, GPUCell
         self->cursor->x++;
     }
     *cpu_cell = (CPUCell){0}; *gpu_cell = (GPUCell){0};
+    if (self->cursor->y == before) init_segmentation_state(self, s);
+    else init_text_loop_line(self, s);
 }
 
 static bool
@@ -984,8 +987,7 @@ draw_combining_char(Screen *self, text_loop_state *s, char_type ch) {
                 CPUCell *second = cp + xpos + 1;
                 if (second->is_multicell) {
                     if (second->y) {
-                        move_widened_char_past_multiline_chars(self, cpu_cell, gpu_cell, xpos, s->prev.y);
-                        init_segmentation_state(self, s);
+                        move_widened_char_past_multiline_chars(self, s, cpu_cell, gpu_cell, xpos, s->prev.y);
                         return;
                     }
                     nuke_multicell_char_at(self, xpos + 1, s->prev.y, false);
@@ -994,8 +996,7 @@ draw_combining_char(Screen *self, text_loop_state *s, char_type ch) {
                 self->cursor->x++;
                 *second = *cpu_cell; second->x = 1;
             } else {
-                move_widened_char_past_multiline_chars(self, cpu_cell, gpu_cell, xpos, s->prev.y);
-                init_segmentation_state(self, s);
+                move_widened_char_past_multiline_chars(self, s, cpu_cell, gpu_cell, xpos, s->prev.y);
             }
         }
     } else if (ch == VS15) {
diff --git a/kitty_tests/screen.py b/kitty_tests/screen.py
index 03ad0d43e..41b81f431 100644
--- a/kitty_tests/screen.py
+++ b/kitty_tests/screen.py
@@ -732,6 +732,10 @@ class TestScreen(BaseTest):
         self.ae(s.text_for_selection(), ('a\u00adb',))
 
     def test_variation_selectors(self):
+        s = self.create_screen(cols=3)
+        q = '*\ufe0f'
+        s.draw(q*(s.columns+1))
+        self.ae(str(s.line(0)), q*(s.columns//2))
         s = self.create_screen(cols=8)
         def widths(text, *widths):
             s.reset()