Allow setting the class for new OS windows in a session file

docs/changelog.rst

@@ -20,6 +20,8 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 
 - Implement support for box drawing rounded-corners characters (:iss:`2240`)
 
+- Allow setting the class for new OS windows in a session file
+
 - When a character from the Unicode Dingbat block is followed by a space, use
   the extra space to render a larger version of the character (:iss:`2850`)
 

docs/index.rst

@@ -346,6 +346,8 @@ For example:
     new_os_window
     # set new window size to 80x25 cells
     os_window_size 80c 25c
+    # set the --class for the new OS window
+    os_window_class mywindow
     launch sh
     # Make the current window the active (focused) window
     focus

kitty/boss.py

@@ -195,7 +195,7 @@ class Boss:
     ) -> int:
         if os_window_id is None:
             opts_for_size = opts_for_size or getattr(startup_session, 'os_window_size', None) or self.opts
-            wclass = wclass or self.args.cls or appname
+            wclass = wclass or getattr(startup_session, 'os_window_class', None) or self.args.cls or appname
             with startup_notification_handler(do_notify=startup_id is not None, startup_id=startup_id) as pre_show_callback:
                 os_window_id = create_os_window(
                         initial_window_size_func(opts_for_size, self.cached_values),

kitty/session.py

@@ -43,6 +43,7 @@ class Session:
         self.active_tab_idx = 0
         self.default_title = default_title
         self.os_window_size: Optional[WindowSizeOpts] = None
+        self.os_window_class: Optional[str] = None
 
     def add_tab(self, opts: Options, name: str = '') -> None:
         if self.tabs and not self.tabs[-1].windows:
@@ -124,6 +125,8 @@ def parse_session(raw: str, opts: Options, default_title: Optional[str] = None)
                 from kitty.config_data import window_size
                 w, h = map(window_size, rest.split(maxsplit=1))
                 ans.os_window_size = WindowSizeOpts(w, h, opts.window_margin_width, opts.window_padding_width, False)
+            elif cmd == 'os_window_class':
+                ans.os_window_class = rest
             else:
                 raise ValueError('Unknown command in session file: {}'.format(cmd))
     yield finalize_session(ans)