Implement auto reload of config

docs/changelog.rst

@@ -181,6 +181,8 @@ Detailed list of changes
 
 - Draw a progress bar at the top of the window when a program reports progress using the OSC 9;4 escape sequence, controlled by :opt:`progress_bar` (:iss:`9777`)
 
+- Automatically reload configuration on changes, controlled by :opt:`auto_reload_config`
+
 - Allow specifying multiple background images for :opt:`background_image` that are stored on GPU to allow fast image switching (:pull:`9836`)
 
 - :doc:`Remote control <remote-control>`: Expose :code:`session_name` and :code:`last_focused_at` in the output of ``kitten @ ls`` for each window (:iss:`9732`, :iss:`9799`)

docs/conf.rst

@@ -16,7 +16,8 @@ frames-per-second. See below for an overview of all customization possibilities.
 You can open the config file within |kitty| by pressing :sc:`edit_config_file`
 (:kbd:`⌘+,` on macOS). A :file:`kitty.conf` with commented default
 configurations and descriptions will be created if the file does not exist.
-You can reload the config file within |kitty| by pressing
+The configuration is automatically reloaded when modified, controlled by
+:opt:`auto_reload_config`. You can manually reload the config by pressing
 :sc:`reload_config_file` (:kbd:`⌃+⌘+,` on macOS) or sending |kitty| the
 ``SIGUSR1`` signal with ``kill -SIGUSR1 $KITTY_PID``. You can also display the
 current configuration by pressing :sc:`debug_config` (:kbd:`⌥+⌘+,` on macOS).

kitty/boss.py

@@ -1390,10 +1390,15 @@ class Boss:
             else:
                 self.startup_first_child(first_os_window_id, startup_sessions=startup_sessions)
 
-        if get_options().update_check_interval > 0 and not self.update_check_started and getattr(sys, 'frozen', False):
+
+        if (opts := get_options()).update_check_interval > 0 and not self.update_check_started and getattr(sys, 'frozen', False):
             from .update_check import run_update_check
             run_update_check(get_options().update_check_interval * 60 * 60)
             self.update_check_started = True
+        if opts.auto_reload_config >= 0 and not hasattr(self, 'config_reload_watcher_process'):
+            self.config_reload_watcher_process = subprocess.Popen(
+                [kitten_exe(), '__watch_conf__', str(os.getpid()), str(int(opts.auto_reload_config * 1000))] +
+                list(opts.all_config_paths), stdin=subprocess.PIPE)
 
     def handle_window_title_bar_mouse(self, os_window_id: int, window_id: int, x: float, y: float, button: int, modifiers: int, action: int) -> None:
         if tm := self.os_window_map.get(os_window_id):

kitty/options/definition.py

@@ -2393,6 +2393,15 @@ reloading the config is not supported.
 '''
     )
 
+opt('auto_reload_config', '0.1', option_type='float', long_text='''
+Automatically reload configuration files when they are changed. The setting
+is the number of seconds to wait before reloading the config files. This allows
+multiple changes to be debounced. Use a negative value to disable automatic reload.
+You can manually reload with :sc:`reload_config_file`. Note that automatic
+reload works only if the :file:`kitty.conf` already exists when kitty is started.
+Changes to this setting by reloading configuration are ignored.
+''')
+
 opt('startup_session', 'none',
     option_type='config_or_absolute_path',
     long_text='''

kitty/options/parse.py

@@ -71,6 +71,9 @@ class Parser:
 
     choices_for_allow_remote_control = frozenset(('password', 'socket-only', 'socket', 'no', 'n', 'false', 'yes', 'y', 'true'))
 
+    def auto_reload_config(self, val: str, ans: dict[str, typing.Any]) -> None:
+        ans['auto_reload_config'] = float(val)
+
     def background(self, val: str, ans: dict[str, typing.Any]) -> None:
         ans['background'] = to_color(val)
 

kitty/options/types.py

@@ -53,6 +53,7 @@ option_names = (
     'allow_cloning',
     'allow_hyperlinks',
     'allow_remote_control',
+    'auto_reload_config',
     'background',
     'background_blur',
     'background_image',
@@ -527,6 +528,7 @@ class Options:
     allow_cloning: choices_for_allow_cloning = 'ask'
     allow_hyperlinks: int = 1
     allow_remote_control: choices_for_allow_remote_control = 'no'
+    auto_reload_config: float = 0.1
     background: Color = Color(0, 0, 0)
     background_blur: int = 0
     background_image: tuple[str, ...] = ()

tools/cmd/tool/main.go

@@ -37,6 +37,7 @@ import (
 	"github.com/kovidgoyal/kitty/tools/cmd/update_self"
 	"github.com/kovidgoyal/kitty/tools/tui"
 	"github.com/kovidgoyal/kitty/tools/utils/images"
+	"github.com/kovidgoyal/kitty/tools/watch"
 )
 
 var _ = fmt.Print
@@ -135,7 +136,7 @@ func KittyToolEntryPoints(root *cli.Command) {
 		},
 	})
 	// __watch_conf__
-
+	watch.EntryPoint(root)
 	// __convert_image__
 	images.ConvertEntryPoint(root)
 	// __atexit__

tools/watch/api.go

@@ -27,7 +27,9 @@ func watch_dirs(ctx context.Context, paths []string, debounce time.Duration, eve
 		fswatcher.WithCooldown(debounce),
 	}
 	for _, path := range paths {
-		opts = append(opts, fswatcher.WithPath(path))
+		if unix.Access(path, unix.R_OK|unix.X_OK) == nil {
+			opts = append(opts, fswatcher.WithPath(path))
+		}
 	}
 	w, err := fswatcher.New(opts...)
 	if err != nil {