Add support for DECSTR soft screen reset escape code

This escape code is largely undefined. There is no specification for how
it affects alternate screen mode, overriden colors, kitty keyboard
state, paused rendering, etc. Do what I feel is sensible in these cases.

Fixes #10263

docs/changelog.rst

@@ -234,6 +234,8 @@ Detailed list of changes
 
 - macOS: Disable macOS one time code autofill popups (:pull:`10250`)
 
+- Add support for DECSTR soft screen reset escape code (:iss:`10263`)
+
 0.47.4 [2026-06-15]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

kitty/screen.c

@@ -173,13 +173,13 @@ new_screen_object(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
 
 static Line* range_line_(Screen *self, int y);
 
-void
-screen_reset(Screen *self) {
+static void
+do_screen_reset(Screen *self, bool is_hard_reset) {
     screen_pause_rendering(self, false, 0);
     self->dnd_chunking.active = false;
     self->extra_cursors.count = 0; zero_at_ptr(&self->extra_cursors.color); self->extra_cursors.dirty = true;
     self->main_pointer_shape_stack.count = 0; self->alternate_pointer_shape_stack.count = 0;
-    if (self->linebuf == self->alt_linebuf) screen_toggle_screen_buffer(self, true, true);
+    if (is_hard_reset && self->linebuf == self->alt_linebuf) screen_toggle_screen_buffer(self, true, true);
     if (screen_is_overlay_active(self)) {
         deactivate_overlay_line(self);
         // Cancel IME composition
@@ -197,11 +197,13 @@ screen_reset(Screen *self) {
     self->last_graphic_char = 0;
     self->main_savepoint.is_valid = false;
     self->alt_savepoint.is_valid = false;
-    linebuf_clear(self->linebuf, BLANK_CHAR);
-    historybuf_clear(self->historybuf);
-    clear_hyperlink_pool(self->hyperlink_pool);
-    grman_clear(self->main_grman, false, self->cell_size);  // dont delete images in scrollback
-    grman_clear(self->alt_grman, true, self->cell_size);
+    if (is_hard_reset) {
+        linebuf_clear(self->linebuf, BLANK_CHAR);
+        historybuf_clear(self->historybuf);
+        clear_hyperlink_pool(self->hyperlink_pool);
+        grman_clear(self->main_grman, false, self->cell_size);  // dont delete images in scrollback
+        grman_clear(self->alt_grman, true, self->cell_size);
+    }
     self->modes = empty_modes;
     self->saved_modes = empty_modes;
     self->active_hyperlink_id = 0;
@@ -218,7 +220,17 @@ screen_reset(Screen *self) {
     screen_cursor_position(self, 1, 1);
     set_dynamic_color(self, 111, NULL);  // does default_bg_changed processing
     colorprofile_reset(self->color_profile);
-    CALLBACK("on_reset", NULL)
+    CALLBACK("on_reset", "O", is_hard_reset ? Py_True : Py_False);
+}
+
+void
+screen_reset(Screen *self) { do_screen_reset(self, true); }
+
+void
+screen_soft_reset(Screen *self) {
+    index_type x = self->cursor->x, y = self->cursor->y;
+    do_screen_reset(self, false);
+    self->cursor->x = x; self->cursor->y = y;
 }
 
 void

kitty/screen.h

@@ -242,6 +242,7 @@ void screen_scroll(Screen *self, unsigned int count);
 void screen_reverse_scroll(Screen *self, unsigned int count);
 void screen_reverse_scroll_and_fill_from_scrollback(Screen *self, unsigned int count);
 void screen_reset(Screen *self);
+void screen_soft_reset(Screen *self);
 void screen_set_tab_stop(Screen *self);
 void screen_tab(Screen *self);
 void screen_backtab(Screen *self, unsigned int);

kitty/vt-parser.c

@@ -1380,11 +1380,19 @@ dispatch_csi(PS *self) {
             }
             break;
         case DECSTR:
-            if (end_modifier == '$') {
-                // DECRQM
-                CALL_CSI_HANDLER1P(report_mode_status, 0, '?');
-            } else {
-                REPORT_ERROR("Unknown DECSTR CSI sequence with start and end modifiers: '%c' '%c'", start_modifier, end_modifier);
+            switch (end_modifier) {
+                case '$': // DECRQM
+                    CALL_CSI_HANDLER1P(report_mode_status, 0, '?'); break;
+                case '!': // Soft reset
+                    if (num_params) {
+                        REPORT_ERROR("DECSTR escape code with parameters is invalid");
+                    } else {
+                        REPORT_COMMAND(screen_soft_reset);
+                        screen_soft_reset(self->screen);
+                    }
+                    break;
+                default:
+                    REPORT_ERROR("Unknown CSI p sequence with start and end modifiers: '%c' '%c'", start_modifier, end_modifier); break;
             }
             break;
         case 'm':

kitty/window.py

@@ -1499,7 +1499,7 @@ class Window:
         b |= b << 8
         self.screen.send_escape_code_to_child(ESC_OSC, f'{code};rgb:{r:04x}/{g:04x}/{b:04x}')
 
-    def on_reset(self) -> None:
+    def on_reset(self, is_hard_reset: bool = True) -> None:
         from .progress import ProgressState
         if self.progress.state is not ProgressState.unset:
             self.progress.update(0)  # unset

kitty_tests/__init__.py

@@ -60,7 +60,7 @@ class Callbacks:
     def notify_child_of_resize(self):
         self.num_of_resize_events += 1
 
-    def on_reset(self) -> None:
+    def on_reset(self, is_hard_reset: bool = True) -> None:
         if self.pty is not None:
             self.pty.reset_termios_state()
 

kitty_tests/screen.py

@@ -1864,6 +1864,57 @@ class TestScreen(BaseTest):
             sc(2, 1, 2, 3, slot=slot)
             sc(5, 13, slot=slot)
 
+    def test_soft_reset(self):
+        SOFT_RESET = b'\x1b[!p'  # DECSTR sequence
+
+        # Screen content is preserved (unlike hard reset)
+        s = self.create_screen()
+        s.draw('hello')
+        parse_bytes(s, SOFT_RESET)
+        self.ae(str(s.line(0)), 'hello')
+
+        # Hard reset clears screen content; soft reset does not
+        s = self.create_screen()
+        s.draw('hello')
+        s.reset()
+        self.ae(str(s.line(0)), '')
+
+        # Cursor SGR attributes are cleared
+        s = self.create_screen()
+        s.select_graphic_rendition(1)   # bold
+        s.select_graphic_rendition(31)  # red fg
+        self.assertTrue(s.cursor.bold)
+        self.assertNotEqual(s.cursor.fg, 0)
+        parse_bytes(s, SOFT_RESET)
+        self.assertFalse(s.cursor.bold)
+        self.ae(s.cursor.fg, 0)
+
+        # Cursor position is preserved
+        s = self.create_screen()
+        s.cursor_position(3, 4)
+        self.ae((s.cursor.y, s.cursor.x), (2, 3))
+        parse_bytes(s, SOFT_RESET)
+        self.ae((s.cursor.y, s.cursor.x), (2, 3))
+
+        # Insert mode (IRM) is cleared
+        s = self.create_screen()
+        s.draw('abcde')
+        s.set_mode(IRM)
+        parse_bytes(s, SOFT_RESET)
+        # without IRM, drawing overwrites
+        s.cursor.x = 0
+        s.draw('X')
+        self.ae(str(s.line(0)), 'Xbcde')
+
+        # Alternate screen is NOT exited on soft reset
+        s = self.create_screen()
+        parse_bytes(s, b'\x1b[?1049h')  # enter alternate screen
+        self.assertFalse(s.is_main_linebuf())
+        parse_bytes(s, SOFT_RESET)
+        self.assertFalse(s.is_main_linebuf())
+        s.reset()
+        self.assertTrue(s.is_main_linebuf())
+
 
 def detect_url(self, scale=1):
     s = self.create_screen(cols=30 * scale)