Writing sessions with on_tab_bar_dirty crashing kitty

[mike-lloyd03]

I've been using the on_tab_bar_dirty watcher for a while now to automatically save my current session but as of the latest kitty, it causes a crash. Below is the watcher. It uses the window class (something like kitty_main) to get the session name and then saves it to ~/.config/kitty/sessions.

import threading

from pathlib import Path
from typing import Any

from kitty.boss import Boss
from kitty.window import Window
from kitty.fast_data_types import current_os_window


def write_session(boss: Boss, session_name: str, blocking: bool = False):
    path = Path(f"~/.config/kitty/sessions/{session_name}").expanduser()

    lock = threading.Lock()
    locked = lock.acquire(blocking=blocking)
    if not locked:
        return
    try:
        with open(path, "w") as f:
            f.write("\n".join(boss.serialize_state_as_session()))
    finally:
        lock.release()

def on_tab_bar_dirty(boss: Boss, window: Window, data: dict[str, Any]) -> None:
    current_os_window_id = current_os_window()
    os_windows = boss.list_os_windows()

    for os_window in os_windows:
        print(f"checking window {os_window['id']}")
        if os_window['id'] == current_os_window_id:
            wname = os_window['wm_name']
            print(f"got wm_name {wname}")
            session_name_parts = wname.split("_", 1)
            if len(session_name_parts) > 1:
                    if session_name_parts[0] == "kitty":
                        write_session(boss, session_name_parts[1])
                        print(f"wrote session {session_name_parts[1]}")

And here's the error message I'm getting during the crash:

Oct 09 23:00:47 kratos kitty[625361]: Traceback (most recent call last):
Oct 09 23:00:47 kratos kitty[625361]:   File "/usr/bin/../lib/kitty/kitty/boss.py", line 1854, in on_focus
Oct 09 23:00:47 kratos kitty[625361]:     tm.mark_tab_bar_dirty()
Oct 09 23:00:47 kratos kitty[625361]:     ~~~~~~~~~~~~~~~~~~~~~^^
Oct 09 23:00:47 kratos kitty[625361]:   File "/usr/bin/../lib/kitty/kitty/tabs.py", line 1129, in mark_tab_bar_dirty
Oct 09 23:00:47 kratos kitty[625361]:     watcher(boss, w, data)
Oct 09 23:00:47 kratos kitty[625361]:     ~~~~~~~^^^^^^^^^^^^^^^
Oct 09 23:00:47 kratos kitty[625361]:   File "/home/mike/.config/kitty/session_save.py", line 36, in on_tab_bar_dirty
Oct 09 23:00:47 kratos kitty[625361]:     write_session(boss, session_name_parts[1])
Oct 09 23:00:47 kratos kitty[625361]:     ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Oct 09 23:00:47 kratos kitty[625361]:   File "/home/mike/.config/kitty/session_save.py", line 20, in write_session
Oct 09 23:00:47 kratos kitty[625361]:     f.write("\n".join(boss.serialize_state_as_session()))
Oct 09 23:00:47 kratos kitty[625361]:             ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Oct 09 23:00:47 kratos kitty[625361]:   File "/usr/bin/../lib/kitty/kitty/boss.py", line 520, in serialize_state_as_session
Oct 09 23:00:47 kratos kitty[625361]:     yield from tm.serialize_state_as_session(session_path, matched_windows, is_first=i==0, ser_opts=ser_opts)
Oct 09 23:00:47 kratos kitty[625361]:                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Oct 09 23:00:47 kratos kitty[625361]:   File "/usr/bin/../lib/kitty/kitty/tabs.py", line 1282, in serialize_state_as_session
Oct 09 23:00:47 kratos kitty[625361]:     ans.extend(tab.serialize_state_as_session(session_path, matched_windows, ser_opts))
Oct 09 23:00:47 kratos kitty[625361]:                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Oct 09 23:00:47 kratos kitty[625361]:   File "/usr/bin/../lib/kitty/kitty/tabs.py", line 315, in serialize_state_as_session
Oct 09 23:00:47 kratos kitty[625361]:     most_common_cwd, _ = Counter(cwds.values()).most_common(1)[0]
Oct 09 23:00:47 kratos kitty[625361]:                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^
Oct 09 23:00:47 kratos kitty[625361]: IndexError: list index out of range

I think with the newer session management features, I should be using this a different way. Probably save_as_session. But kitten @ save_as_session says that command is unknown so I'm not sure if using boss.call_remote_control(save_as_session) would work either.

I feel like I'm missing something obvious here. Anyone who can help?

[kovidgoyal]

That error indicates you have a tab without any windows, it is fixed already in master. If you want to use save_as_session you would do kitten @ action save_as_session ... the same applies when using it via Python.