Save current os window's tab into a session

[jackielii]

Today I tried to setup Kitty Session similar to the Tmux experience I had: press ctrl+a>S to save current os_window tabs to a session

Turns out not as easy as I thought. There were two problems with it:

1. I can't have a --match selector that selects all tabs in current os window
2. somehow the order of the tabs saved are reversed.

So I created:

1. save session kitten (central place for session file ~/.local/share/kitty/sessions/)
2. fzf select session kitty (no need to declare goto_session in kitty.conf)

maps in kitty.conf:

map ctrl+a>ctrl+s kitten save_current_os_window_session.py --use-foreground-process .
map ctrl+a>l launch --type=overlay ./fzf_goto_session.sh

save session kitten:

import os
from kittens.tui.handler import result_handler

@result_handler(no_ui=True)
def handle_result(args, answer, target_window_id, boss):
    """Save a session containing only tabs from the current OS window."""

    # Get the active tab to find which OS window we're in
    active_tab = boss.active_tab
    if not active_tab:
        return

    # Get the TabManager for the current OS window
    tab_manager = active_tab.tab_manager_ref()
    if not tab_manager:
        return

    # Collect all windows from all tabs in the current OS window
    matched_windows = set()
    for tab in tab_manager.tabs:
        for window in tab:
            matched_windows.add(window)

    # Parse options and get session path
    from kitty.session import parse_save_as_options_spec_args

    # args[0] is the kitten name, rest are the actual arguments
    opts, remaining_args = parse_save_as_options_spec_args(list(args[1:]))

    session_path = remaining_args[0] if remaining_args else None

    # Handle the '.' shortcut for current session
    if session_path == '.':
        from kitty.session import seen_session_paths
        sn = boss.active_session
        session_path = seen_session_paths.get(sn) or ''

    if not session_path:
        # Prompt for filename
        boss.get_save_filepath(
            'Session file name',
            'session',
            save_session_callback,
            (frozenset(matched_windows), opts)
        )
    else:
        # Expand path and save directly
        session_path = os.path.expandvars(os.path.expanduser(session_path))
        save_session_for_os_window(boss, session_path, frozenset(matched_windows), opts)


def save_session_callback(session_path, data):
    """Callback for when user provides session path via dialog."""
    if session_path:
        from kitty.boss import get_boss
        matched_windows, opts = data
        boss = get_boss()
        save_session_for_os_window(boss, session_path, matched_windows, opts)


def save_session_for_os_window(boss, session_path, matched_windows, opts):
    """Actually save the session with the matched windows."""
    from kitty.config import atomic_save

    # Use the provided options
    ser_opts = opts

    # Resolve the path like save_as_session_part2 does
    session_path = os.path.abspath(os.path.expanduser(session_path))

    # Get the TabManager for serialization
    active_tab = boss.active_tab
    if not active_tab:
        return
    tab_manager = active_tab.tab_manager_ref()
    if not tab_manager:
        return

    # Build session content manually for just this OS window
    # Iterate through tabs in visual order (not history order)
    lines = ['# kitty session saved from current OS window only']
    for tab in tab_manager:
        lines.extend(tab.serialize_state_as_session(
            session_path,
            matched_windows=matched_windows,
            ser_opts=ser_opts
        ))

    # Write the session file
    try:
        os.makedirs(os.path.dirname(session_path), exist_ok=True)
        session = '\n'.join(lines)
        atomic_save(session.encode(), session_path)
        boss.show_error('Session Saved', f'Session saved to {session_path}')
    except Exception as e:
        boss.show_error('Failed to save session', str(e))


def main(args):
    # Arguments will be passed from the mapping
    pass

fzf switch:

#!/bin/bash

# Directory containing session files
SESSION_DIR="$HOME/.local/share/kitty/sessions"

# Check if session directory exists
if [[ ! -d "$SESSION_DIR" ]]; then
    echo "Session directory not found: $SESSION_DIR"
    exit 1
fi

# Find all session files and use fzf to select one
selected=$(find "$SESSION_DIR" -name "*.session" -o -name "*.kitty-session" | \
    sed "s|$SESSION_DIR/||" | \
    fzf --prompt="Select session: " \
        --layout=reverse \
        --border \
        --preview="cat $SESSION_DIR/{}" \
        --preview-window=right:60%)

# If a session was selected, goto it
if [[ -n "$selected" ]]; then
    session_path="$SESSION_DIR/$selected"
    # Use kitten @ action to execute goto_session
    kitten @ action goto_session "$session_path"
fi

Source: https://github.com/jackielii/dotfiles/tree/main/.config/kitty

disclaimer: claude code wrote most of this code